INCO-CT2006-032539
CAMINAR
Catchment Management and Mining Impacts
in Arid and Semi-Arid South America
Instrument: Specific Targeted Research Project
Thematic Priority: A.2.3 Managing arid and semi-arid ecosystems
Deliverable 5
Technical Report on River Basin Characteristics, Pressures and Issues
(Elqui)
Due date of deliverable: Month 12
Actual submission date: Month 14
Start date of project:
1 February 2007
Duration: 36 months
Organisation name of lead contractor for this deliverable: CAZALAC
(final)
Project co-funded by the European Commission within the Sixth Framework Programme
(2002-2006)
Dissemination Level
PU
PP
RE
CO
Public
Restricted to other programme participants (including the Commission Services)
Restricted to a group specified by the consortium (including the Commission Services)
Confidential, only for members of the consortium (including the Commission Services)
X
European Commission Sixth Framework Programme
Specific International Scientific Cooperation Activities (INCO)
Activity Area: A. Developing countries
A2. RATIONAL USE OF NATURAL RESOURCES
A.2.3. Managing arid and semi-arid ecosystems
Specific Targeted Research or Innovation Project CAMINAR
Contract No. INCO-CT2006-032539
Catchment Management and Mining Impacts
in Arid and Semi-Arid South America
D5
Technical Report on River Basin Characteristics, Pressures
and Issues. Elqui River Basin, CHILE
January 2008
Authors:
Ricardo Oyarzún1, Jorge Oyarzún1,2, Michelle Señoret3, Hugo Maturana1,2,
Karine Orth1, Guido Soto3, Manuel Soto3, Nicole Kretschmer1.
1
Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad de La Serena –
Chile.
2
Departamento Ingeniería de Minas, Universidad de La Serena – Chile
3
Centro del Agua para Zonas Áridas y Semiáridas de América Latina y el Caribe
(CAZALAC), La Serena – Chile
Editor:
Tobias S. Rötting4
4
University of Newcastle upon Tyne – United Kingdom
Centro del Agua para Zonas Aridas y Semiáridas de América Latina y el Caribe (CAZALAC), La Serena – Chile
Telephone: ++56 51 204493 / 334811
Email: [email protected]
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
EXECUTIVE SUMMARY
The Elqui River watershed is an arid basin located in the Coquimbo Region, North Central Chile, in
the so-called “Norte Chico” area, and it extends between 29º27`−30º34`S and 71º22`−69º52` W,
covering an area of ca. 9,700 km2 . The geology of the basin comprises Lower Palaeozoic to Upper
Tertiary, calco-alkaline plutonic and volcanic rocks (lava flows and pyroclastic rocks), with some
marine sedimentary intercalations of Jurassic and Lower-Cretaceous age. The rocks-massifs are highly
fractured and those of Cretaceous and Tertiary age present abundant mineral deposits (Cu, Au, Ag,
Mn, As) and hydrothermal alteration zones. The Climate of the Elqui basin includes a periodic water
scarcity, as result of variability in precipitation, which is manifested in long and persistent dry periods.
However, the ENSO phenomenon has a great influence in the climatic oscillations in this area,
provoking extreme wet and dry periods in El Niño and La Niña years, respectively. Annual rainfall
amounts ca. 90−100 mm, and tend to be concentrated in the April-September (autumn−winter) period
(Vuille and Milana, 2007). Despite the arid and variable climatic conditions, the Elqui basin (as other
basins of the arid belt) has undergone an important development of the agricultural and agro-industrial
activities, which are supported by an extensive system of irrigation channels, over 117 channels of
almost 750 km length, which allow irrigated agriculture for over 13,000 has. In addition, the mild
climate, alluring landscapes, large and white sand beaches and other regional appeals, have attracted a
large and fast growing population to the La Serena-Coquimbo conurbation, which reached some
322.562 inhabitants in 2003, ca. 88% of the total population of the basin, and that has an important
increase during the summer tourist season, coincidental with the driest time of the year. Mining has
been also historically important in the area, and the high metal prices of the last years, in particular Cu
and Au, have fostered a re-activation of the mining industry. Three mining districts in the Elqui basin
are of major importance, although they differ in terms of the type and relevance of its polluting effects
on the watershed: the Andacollo, Talcuna, and El Indio districts. In addition to these districts (and
mining operations), a large number of ore deposits (Cu, Ag, Au ores, with minor contents of Zn, Pb,
As, etc.) were mined during the 19th and 20th centuries. These operations have left a heritage of
barren and low-grade material, tailings of the sulphide concentration processes, acid (Cu) and alkaline
cyanide (Au) bearing leach pile wastes, and minor residues of mercury related to gold recovery. Also,
the cavities left by mining collect groundwater, enhancing water-rock interaction, the transport of
soluble salts containing heavy metals, and in some cases, the generation of acid drainage. Thus, the
combination of all these factors (aridity, water competing economic activities) are starting to create
problems at the watershed level that must be addressed before it is too late.
i
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Index
EXECUTIVE SUMMARY.........................................................................................................................I
INDEX........................................................................................................................................................ II
Acronyms and Abbreviations ..............................................................................................................iii
List of figures ........................................................................................................................................ iv
List of tables .......................................................................................................................................... vi
1
INTRODUCTION ............................................................................................................................. 1
2
ELQUI RIVER BASIN ..................................................................................................................... 3
2.1
General Traits ............................................................................................................................. 3
2.1.1
Physiography.......................................................................................................................... 3
2.1.2
Geology, lithology and mineralogy........................................................................................ 4
2.1.3
Climate ................................................................................................................................... 7
2.1.4
Hydrology .............................................................................................................................. 8
2.1.5
Ecological aspects ................................................................................................................ 10
2.1.6
Cultural Heritage.................................................................................................................. 11
2.1.7
Economic activities. ............................................................................................................. 11
2.1.8
Water requirements .............................................................................................................. 19
2.1.9
Socioeconomic characterization........................................................................................... 21
2.2
Pressure and Issues ................................................................................................................... 22
2.2.1
Governmentally Supported Development Programs............................................................ 22
2.2.2
Current Scenario for Science and Technology Development............................................... 23
2.2.3
Water quality monitoring and secondary water quality regulations ..................................... 23
2.2.4
Climate change..................................................................................................................... 24
2.2.5
Integrated watershed management ....................................................................................... 25
2.2.6
Growing Economies and International Forcers .................................................................... 26
2.2.7
Current and Prospective Problems ....................................................................................... 26
3
CONCLUSIONS.............................................................................................................................. 30
4
REFERENCES ................................................................................................................................ 31
ii
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Acronyms and Abbreviations
CAMINAR:
Catchment Management and Mining Impacts in Arid and Semi Arid South America.
ENSO:
El Niño Southern Oscillation
CAZALAC:
Centro del Aguas para Zonas Áridas y Semiáridas de America Latina y el Caribe
SNASPE:
Sistema Nacional de Áreas Silvestre Protegidas
CONAMA:
Comisión Nacional del Medio Ambiente
CEAZA:
Centro de Estudios Avanzados en Zonas Áridas
CONICYT:
Comisión Nacional de Investigaciones Científico y Tecnológicas
DGA:
Dirección General de Aguas.
SX-EM:
Metallurgical process (solvent extraction/electro-winning)
iii
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
List of figures
Figure 1: Google earth image of Chile (Panel A) and Political-administrative division in Regions
(Panel B) highlighting in red the Coquimbo Region. The Atacama region is the immediately northern
one.
Figure 2: Google earth image showing the mountainous landscape of the Coquimbo Region (Panel A)
and Provinces (coincident with major E-W basins) (Panel B).
Figure 3: Elqui River Basin showing major cities and towns, rivers and water reservoirs, and mine
districts.
Figure 4: Panel A: Schematic representation of the major geomorphological units layout in the
Coquimbo Region (“Alta Montaña”: Andean High Mountains; “Montaña Media”: Middle Mountains;
“Valle del Elqui”, “Valle del Limarí”, “Valle del Choapa”: Fluvial Valleys; “Franja Costera”: Coastal
Border) (Taken from Cepeda, 2006); Panel B: Altitudinal range for the Elqui basin (Galleguillos,
2005).
Figure 5: Geology of the Elqui River basin: 1) Alluvial Quaternary sediments; 2) Mesozoic-Cenozoic
volcanic and volcanic-sedimentary rocks; 3) Paleozoic and Mesozoic granitoids; 4) Hydrothermal
alteration zones (source: Oyarzún et al. 2003)
Figure 6: Partial view of the main fracturing network and ore deposits of the Coquimbo Region
Figure 7: Geologic map of the Elqui river basin and nearby, highlighting the small aerial extension
represented by Quaternary alluvial sediments (Qa), only concentrated in the mid to lower part of the
watershed in the nearby of the river.
Figure 8: Typical landscape of hydrothermally altered zones in the upper Elqui Valley (left image
taken from Cepeda 2004, after Galleguillos, 2005)
Figure 9: Annual average rainfall amount for several localtions of the Elqui sub-basin.
Figure 10: Schematic representation of the main tributaries of the Elqui river basin
Figure 11: La Laguna reservoir in the upper Elqui basin
Figure 12: Puclaro Reservoir in the mid Elqui basin, general overview (left panel) and downstream
landscape view (right panel)
Figure 13: General overview of aquifer sectors as defined by CAZALAC-RHODOS, 2006
Figure 14: Archaeological sites in the Elqui basin and nearby (taken from Mena, 2002)
Figure 15: Different views of the agricultural and turistic activities of the Elqui valley (A to C own
images. Image D taken from “Turismo Cochiguaz” at http://images.google.cl/imgres? imgurl=
http://turismocochiguaz.nireblog.com/
Figure 16: Views of Cerro Brillador (A) and the Santa Gracia gulch (B)
Figure 17: Landscape views of the Talcuna district and the existing mining operations
Figure 18: Flash flood events associated with El Niño years that have provoke tailing removal and
transportation
Figure 19: A: General overview of the location of the Andacollo district (red circle) with respect to the
Elqui Basin. B: Schematic representation of the relation between the Andacollo area and the Elqui
basin through the Los Negritos-El Arrayán drainage system; C: Los Negritos gulch showing
abandoned tailing deposits; D: El Arrayán overview.
Figure 20: A: Google earth image showing the location of the Andacollo district (red circle), the Pan
de Azucar agricultural basin (green circle), the Elqui river (blue segmented line), the Bellavista
channel (light blue segmented line) and the access road to Andacollo (black segmented line); B:
Agricultural activity in the Pan de Azúcar land.
iv
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 21: General overviews of the Andacollo mine activities
Figure 22: General overview of the El Indio district
Figure 23: Webpages showing nation-wide and local government efforts to transform Chile into a
world-wide food producer leading country
Figure 24: DGA and CONAMA surface water and groundwater monitoring and sampling network in
the Limarí Province.
Figure 25: CONAMA´s efforts toward Integrated Watershed Management.
Figure 26: Example of a recent mining related environmental problem (taken from El Tiempo”
newspaper, Week of 6-12 July, 2007)
Figure 27: Newspaper information regarding the Pan de Zúcar-Andacollo rising conflict (left news
dated from the week 27 April-3 May, 2007; right information is for the week of 25-31 January, 2008).
Figure 28: General overview of the geological characteristics of the Pascua Lama deposit, Atacama
Region.
v
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
List of tables
Table 1. Consumptive water demand for the Elqui river basin
20
Table 2. Actual required amount of water by different sectors given the inefficiencies.
20
Table 3. Coquimbo Region Exports Evolution by Sector
22
vi
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
1 INTRODUCTION
The Elqui River watershed is an arid basin located in the Coquimbo Region, North Central Chile, in
the so-called “Norte Chico” area, which includes the Atacama and the Coquimbo Regions, within the
27º−33º S belt (Figure 1).
A
B
Figure 1: Google earth image of Chile (Panel A) and Political-administrative division in Regions (Panel B)
highlighting in red the Coquimbo Region. The Atacama region is the immediately northern one.
Both of them are characterized for the presence of unique geologic-geomorphologic traits that are
different to the other Regions of Chile, such as the lack of a north-south tectonic valley (Central
Valley) that exists toward the north and the south. Also, there is neither recent volcanic activity nor an
important N−S trending tectonic valley filled with alluvial sediments (Arumí and Oyarzún, 2006).
Instead, a major proportion of these Regions’s surface corresponds to hard rock outcrops with variable
degrees of both hydrothermal alteration and fracturing conditions, while the soils are characterized for
presenting poor development, and for being shallow, well drained, and with low water retention
capacity (Oyarzún and Alvarez, 2001).
Several narrow E-W fluvial valleys constitute the physical basis for the administrative organization of
these Regions in Provinces (from North to South): Copiapó and Huasco (Atacama Region) and Elqui,
Limarí, and Choapa (Coquimbo Region) (Figure 2).
1
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
B
A
Elqui River basin
Limari River basin
Choapa River basin
Figure 2: Google earth image showing the mountainous landscape of the Coquimbo Region (Panel A) and
Provinces (coincident with major E-W basins) (Panel B).
The following paragraphs will focus on the Elqui River watershed for it is the area of interest
(demonstrative basin) for the CAMINAR project in Chile. However, as explained above, several
physiographic, hydrological, geological, and water management traits to be discussed are
representative of the other watersheds of the Norte Chico area where arid conditions and mining
activities are present. Consequently, the descriptions hereby delivered as well as the activities done
within CAMINAR are of similar interest, pertinence and applicability for the whole area.
2
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
2 ELQUI RIVER BASIN
2.1
General Traits
2.1.1 Physiography
The Elqui river watershed extends between 29º27`−30º34`S and 71º22`−69º52` W, covering an area of
ca. 9,700 km2 (Fig. 1). It includes three sub-watersheds: Turbio River (ca. 4,200 km2), Claro River
(ca. 1,550 km2), and Elqui river basins (ca. 3,950 km2) (Galleguillos, 2004).
Figure 3: Elqui River Basin showing major cities and towns, rivers and water reservoirs, and mine
districts.
The basin extends between the Andean mountains and the Pacific ocean over a length of only 150 Km.
Thus, the watershed, as other river-basins of the 27º−33ºS belt, presents extreme altitude differences
between its head and its discharge point at the sea: about 5 km for a horizontal distance of ca. 150 km,
which favours the existence of turbulent rivers that can be classified as a “mountain rivers” (Lecomte
et al. 2005).
Four major geomorphologic units are recognized (Paskoff, 1993) (Figure 4): Andean High Mountains
(elevations above 3,000 m), Middle Mountains (hills with elevations between 600 and 3,000 m, highly
dissected with both non-permanent and permanent small discharge streams), Fluvial Valleys (E-W
oriented terraces) and Coastal Border (broad marine and fluvio-marine terraces). The High Mountain
corresponds to the eastern sector, associated with the Andes Cordillera, with altitudes of 3,000 m and
above, where glaciers can still be seen. The Middle mountain unit presents altitudes between 600 and
3,000 masl. It is characterized by the presence of minor mountain ranges. Far from the coastal
influences, this area tends to exhibit high arid conditions. As stated by Cepeda et al. (2004), “these
inter-fluvial landforms have always been marginal land whose population has been focused on
subsistence agriculture”. Thus, it is possible to find extreme vegetation destruction due to wood
chopping for mining purposes, coal production and goat overgrazing. The Coastal band, a very typical
3
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
regional landscape, comprises landforms with altitudes lower than 600 masl, where wide marine
terraces are associated at its eastern margin with alluvial cones, debris near the base of the mountains
and debris cones (Cepeda et al. 2004). Finally, the Fluvial Valleys tends to be narrow in the upper
parts (e.g., 3 km wide near the town of Vicuña) and gets wider through the middle and lower sections
of the rivers exhibiting terraces formations, although never exceeding 5 to 6 km (Oyarzún et al. 2003).
A
B
Figure 4: Panel A: Schematic representation of the major geomorphological units layout in the Coquimbo
Region (“Alta Montaña”: Andean High Mountains; “Montaña Media”: Middle Mountains; “Valle del
Elqui”, “Valle del Limarí”, “Valle del Choapa”: Fluvial Valleys; “Franja Costera”: Coastal Border)
(Taken from Cepeda, 2006); Panel B: Altitudinal range for the Elqui basin (Galleguillos, 2005)
2.1.2 Geology, lithology and mineralogy
The geology of the basin comprises Lower Palaeozoic to Upper Tertiary, calc-alkaline plutonic and
volcanic rocks (lava flows and pyroclastic, volcanic sandstones and conglomerates), with pelitic and
carbonatic marine sedimentary intercalations of Jurassic and Lower-Cretaceous age (Fig. 5). The
rocks-massifs are highly fractured along N-S, NW and NNE directions (Figure 6), and those of
Cretaceous and Tertiary age present abundant hydrothermal alteration zones and mineral deposits (Cu,
Au, Ag, Fe, Mn).
4
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 5: Geology of the Elqui River basin: 1) Alluvial Quaternary sediments; 2) Mesozoic-Cenozoic
volcanic and volcanic-sedimentary rocks; 3) Palaeozoic and Mesozoic granitoids; 4) Hydrothermal
alteration zones (source: Oyarzún et al. 2003)
Figure 6: Partial view of the main fracturing network and ore deposits of the Coquimbo Region
In tectonic terms, to main phases are recognized, a Jurassic to Lower Cretaceous one, corresponding to
the Marianas extensive type and a Chilean or Andean compressive one, that begins in the Upper
Cretaceous (Oyarzún, 1998, Oyarzún, 2000, Oyarzún et al. 2003). The chemical composition of the
igneous and clastic rocks (presenting a volcanic protolith) is rather homogeneous for the whole basin
as a consequence of their common origin: intermediate calc-alkalic, partly shoshinitic magmas,
produced by the subduction of oceanic plate under the granodioritic continental crust (Oyarzún, 2000).
This composition corresponds, in average, to that of andesitic to dacitic rocks. During the Lower
Cretaceous both normal to oblique subduction occurred, accompanied by sinistral strike-slip
displacements in the Atacama mega-fault zone, on the east border of the Coastal Cordillera (Oyarzún
et al, 2003). The fact that most of the surface of the Elqui basin correspond to high relief rock
outcrops, implicates that Quaternary alluvial sediments, and therefore alluvial aquifers, have relatively
low volumes, except in the Elqui river plain and neighbouring alluvial terraces in the lower parts of the
valley (Fig. 7).
5
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 7: Geologic map of the Elqui river basin and nearby, highlighting the small aerial extension
represented by Quaternary alluvial sediments (Qa), only concentrated in the mid to lower part of the
watershed in the nearby of the river.
On the other hand, fractured and altered volcanic rocks strata present an important secondary
permeability and thus behave as effective but, low permeability aquifers. In fact, although their
potential has not been assessed yet, they are used at a local scale in several areas of the watershed for
irrigation and for small villages drinking purposes. During times of extensive dry periods, local
farmers also use the water accumulated on abandoned underground mines.
At a local scale, the high-altitude domain of the region comprises a series of volcanic sequences of
Cenozoic age, among which two are particularly important in terms of metallogenic development: the
Doña Ana Formation, with rhyolites, rhyolitic tuffs, andesites and basaltic andesites, and the so-called
Infiernillo Unit. Also, more than 30 large hydrothermal alteration zones can be defined in N−S belt of
ca. 200*20 km. Many of these zones include advanced argillic alteration mineral assemblages, with
kaolinite, alunite, and silica jaspers (Oyarzún et al., 2007) (Fig. 8).
6
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 8: Typical landscape of hydrothermally altered zones in the upper Elqui Valley (left image taken
from Cepeda 2004, after Galleguillos, 2005)
In the lower parts of the valley, between the Andean Cordillera and the Coastal border, it is possible to
find Cretacic and Tertiary volcanic-sedimentary series with dominance of andesitic lithologies, as well
as granodioritic intrusives of similar age. Near the coastal border there are several levels of alluvial
terraces of Upper Tertiary to Holocene age, with predominance of continental clastic and rock-detritus
sediments and fosiliferous marine inserts.
2.1.3 Climate
The Climate of the Coquimbo Region, and therefore of the Elqui valley, is affected by the interaction
of three factors: (a) The southeast Pacific anticyclone, blocking frontal precipitation systems; (b) The
cold Humboldt current along the Pacific coast; and (c) The Andes mountains, which create a
longitudinal barrier to the westerly winds (Kalthoff et al. 2002; Cepeda et al. 2004). Thus, the climatic
characteristics of the area include a periodic water scarcity, as result of variability in precipitation,
which is manifested in long and persistent dry periods (Santibañez, 1985). However, the ENSO
phenomenon has a great influence in the climatic oscillations in this area, provoking extreme wet and
dry periods in El Niño and La Niña years, respectively (Cepeda et al. 2004; Mena, 2002), as
exemplified in Fig. 9.
Figure 9: Annual average rainfall amount for several locations of the Elqui sub-basin.
7
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
The combination of low ocean temperatures and high land surface temperatures leads to the evolution
of sea breezes which in regions like the Elqui valley superimpose with the valley winds, so that strong
up-valley winds can be observed during daytime (Kalthoff et al. 2006). On the coastal zone and until
some 40 km inland, a Coastal steppe climate with abundant clouds prevails. Toward the valley, and
above 800 m of altitude, there is a warm steppe climate, characterized by the lack of cloudiness and
higher temperatures. Finally, in the Andean Cordillera area, above 3,000 m of altitude, there is a
moderate cold climate with higher precipitations, lower temperatures and everlasting show
accumulations (Llanca and Miranda, 2003). Also, it is common to find local microclimates through the
valley, that allow the cultivation and grown of mediterranean and subtropical species such as papaya,
mango, avocado, lemons, and grapevine.
2.1.4 Hydrology
The general hydric regime for the watershed is arid, with 9 to 10 months of the year without
precipitation, whereas in the northern part of the basin, a hyper-arid regime, with 11 to 12 dry months,
exists (CAZALAC, 2006). Annual rainfall amounts ca. 90−100 mm, and tend to be concentrated in the
April-September (autumn−winter) period (Vuille and Milana, 2007). Also, there is an unknown but
regarded as important amount of precipitation that fall as snow in the Cordillera areas. A major part of
the precipitation in the watershed occurs between May and August (Pérez, 2005), and the higher
runoff (controlled by snow-ice melting), takes place in spring-summer. Thus, both water sources,
snow and ice, constitute the source for the base discharge in the Elqui basin. Actual evapotranspiration
ranges between 65 and 750 mm/year for native vegetation and irrigated agricultural crops respectively
(Kalthoff et al. 2006).
The main river of the watershed, the Elqui, is formed by from the confluence of the Claro and Turbio
rivers (Figure 10). The latter originates from the confluence of Rio del Toro, which drains the Au-CuAs mining district of El Indio, and the La Laguna River, partly sustained by melting of the receding El
Tapado glacier. The Claro River originates from the confluence of the rivers Derecho and Cochiguaz.
From the headwaters to the Pacific Ocean, the Elqui River system receives water contributions from
several streams, some of them permanent and other ephemeral. Among the main creeks there are the
Santa Gracia and Marquesa, at the North side of the Elqui River, and Arrayán, Talca, and San Carlos
at the South side (Llanca and Miranda, 2003).
Figure 10: Schematic representation of the main tributaries of the Elqui river basin
8
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Average discharge is highly variable in the Elqui River watershed in both space and time. The Turbio
River exhibits annual average discharge between 0.8 and 7.1 m3/s; in the Claro River the annual
average discharge ranges between 1.5 and 4.5, while in the Elqui River it ranges between 4.3 and 12.5
m3/s (Galleguillos, 2004). Also, due to the ENSO cycle, the Elqui runoff has been historically highly
variable (e.g. as low as 2.4 and as high as 33 m3/s or even greater). However, the existence of the
Andean La Laguna reservoir (30o 08’ S; 70o 04’ W; 40 Mm3 of capacity), operating since 1941 (Figure
11), and the recent (1999) construction and operation (firstly filled with water by November, 2002) of
the Puclaro dam (30o 00’ S; 70o 50’ W; 200 Mm3 of capacity) (Figure 12) has contributed to regulate
the river discharge specially in the lower course of the river. Also, the main irrigation channels of the
watershed are downstream the Puclaro dam (Galleguillos, 2004)
Figure 11: La Laguna reservoir in the upper Elqui basin
Figure 12: Puclaro Reservoir in the mid Elqui basin, general overview (left panel) and downstream
landscape view (right panel)
Regarding groundwater, it is present in two types of aquifers. The better known are the rather shallow
sediments of the flood plains of valleys and gulches were groundwater and surface runoff are in direct
contact (e.g., non-confined aquifer). Since there are some differences in their elastic and hydraulic
properties, it is possible to distinguish different sectors on it (Figure 13). The number of sectors
identified depends on each study, but in general it is possible to distinguish the following (Llanca and
Miranda, 2003): (1) Upper parts of the watershed that includes the “valleys” of the Claro and Turbio
rivers; (2) Between the towns of Algarrobal and Vicuna; (3) Between Vicuna and El Tambo; (4)
Between El Tambo and Punta Piedra; and (5) Between Punta Piedra and the outlet (desembocadura).
Storage coefficient range between 0,5% and 1% approximately, permeabilities are highly spatially
variable, between 0.1 to 100 m/day, and the hydraulic gradient fluctuates between 0,01 to 0,03. A
9
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
useful compilation of several studies developed in the last years is done by Llanca and Miranda (2003)
and CAZALAC-RHODOS (2005).
Figure 13: General overview of aquifer sectors as defined by CAZALAC-RHODOS, 2006
The second type of aquifer corresponds to fractured rock massifs, both granitic batholiths and volcanic
and sedimentary beds. Due to regional or localised hydrothermal processes, the Mesozoic volcanic
rocks were pervasively replaced by secondary minerals such as calcite, epidote, prehenite, zeolite,
among others. Given that some of these minerals (e.g., calcite) were dissolved by hydrolytic processes,
the rocks have developed large voids and high secondary permeability. Groundwater from these rocks
is currently obtained from natural springs in the mountains and used on a small scale for human
consumption and irrigation purposes by local farmers (Strauch et al., 2006; Luengo et al., 2006).
2.1.5 Ecological aspects
For the Elqui river basin, ecological aspects have been heterogeneously addressed. While there is a
good knowledge of flora and fauna, fresh water biology studies are rather scarce. Nevertheless, it is
acknowledge that the Coquimbo Region, in terms of flora, is within the top 25 higher diversity areas
of the world (Squeo et al. 2001). For the Elqui river basin, both altitude and relief are described as
determining factors for vegetation formations (Osorio et al. 2006). Despite the biological diversity,
there are not yet areas within the Elqui river basin belonging to the SNASPE, the Chilean System of
Wildlife Areas Protected by the Government (CONAMA, 2005). Nevertheless, the “Native Flora Red
Book” (Squeo et al., 2001) recognized 5 sites with high priority for conservation purposes. According
to Cepeda et al. (2004), the arid conditions of the watershed, determined by the climatic and
geomorphological traits, as well as the fact that the economic activity is concentrated at low and
middle elevations, determine that the better preserved natural systems are in the high mountains area.
Hilly areas show a more diverse biota, in special flora and bird-fauna, although not excellent
specialized habitats, except for the case old “loreras” (Cyanoliseus patagonus), “viscacheras”
(Lagidium viscacia), and “chinchilleras” (Chinchilla lanigera). Most of the significant wild life,
biodiversity and endemism are constrained to the humid soils on the basin higher fields, the so-called
“veranadas” (summer pastures). In general, there are an important number of endemic species, as well
as a considerable fauna and flora diversity (Mena, 2002).
10
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Regarding fauna, Cepeda and Novoa (2006) stated that the main groups are those formed by mammals
such as Guanacos (Lama Guanicoe), insects (Hymenópteros, Dípteros y Lepidópteros), grain-feed and
insect-feed birds (Fringillidae), foxes (Pseudalopex culpaeus), hare (Lepus capensis), wild mice
(Phyllotis sp., Abrothrix sp.) and small lizards (Liolaemus sp.).
Normally, rivers and tributaries tend to be rather poor in aquatic biota, being the most important
species the Chilean freshwater silverside fish. Fresh water macro-invertebrates are rather unknown and
there is a lack of information. Cepeda et al. (2006), focused on the biota of the Andean wetland of
Tambo-Puquios (Doña Ana Cordillera) delivered and inventory of some invertebrates. They described
the presence of Turbellaria worms (locally known as “planarias”), Trichoptera and Ephemeroptera
larvae, as well as other insects. Orth (unpublished results) has also found the presence of several
groups such as Trichoptera, Plecoptera, Ephemeroptera, Diptera, Hirudinea, and Oligochaeta in the
Estero Derecho tributary of the Elqui river basin.
2.1.6 Cultural Heritage
As stated by Mena (2002), the Elqui valley was habited in the pre-hispanic time by several agricultural
groups from 8000 yr bp. There are plenty of testimonies of this occupation in arqueological sites, most
of them being placed in private agricultural fields (Fig. 14). Among the native clans highlights the
Diaguita one, from 800 to 1400 DC. Also, the city of La Serena is the second oldest city in Chile,
established by the Spanish conquerors in 1544. Since it was destroyed by the native populations, it was
re-established in 1549 by Francisco de Aguirre.
Figure 14: Archaeological sites in the Elqui basin and nearby (taken from Mena, 2002)
2.1.7 Economic activities.
Despite the arid and variable climatic conditions, the Elqui basin (as other basins of the arid belt) has
undergone an important development of the agricultural and agro-industrial activities, which are
11
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
supported by an extensive system of irrigation channels, over 117 channels for extending for almost
750 km, which allow irrigated agriculture for over 13,000 has. Although the river has not been legally
declared as fully-allocated by the DGA (regional water authority), in practice there has not occurred
creation and allocation of new water rights for the use of the surface waters lately. The agricultural
development has been also enhanced by the successful application of new agronomical practices (soil
conditioning, irrigation techniques, crop improvements through biotechnology and management
practices) and by the opening of foreign markets to its valuable products. Thus, the Elqui valley
agricultural production is now worth of 40 million dollars a year, being one of the most important crop
table grape for foreign markets (Fig. 15). Also, an important agro-industrial sector, the Pisco brandy
production, depends on the grapevine production. This situation, in combination with the important
increment on the agricultural surface with permanent crops (fruit trees such as lemons, sweet oranges
and grapevine) occurred in the recent years, allows to expect that the groundwater resource will start
to receive more attention and an increasing pressure for its use in the coming years.
In addition, the mild climate, alluring landscapes, large and white sand beaches and other regional
appeals, have attracted a large and fast growing population to the La Serena-Coquimbo conurbation,
which reaches some 322.562 inhabitants (2003), ca. 88% of the total population of the basin, and that
has an important increase during the summer tourist season, coincidental with the driest time of the
year (Fig. 15). In particular, the Elqui valley is world-wide recognized for its clear, pristine skies that
have attracted the attention of both professional and amateur’s astronomists. Regarding the former,
there are two observatories, Tololo (AURA-USA) and Pachón. Because of tourism, the urban areas
and urban populations highly increase in summer months, are therefore highly dependent of the basin
water resources, both in terms of quantity and quality.
A
B
D
C
Figure 15: Different views of the agricultural and touristic activities of the Elqui valley (A to C own
images. Image D taken from “Turismo Cochiguaz” at http://turismocochiguaz.nireblog.com/
12
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Mining has been also historically important in the Elqui basin, both as a complementary activity to
small farming (in particular small scale gold mining) and as an independent economic activity. After
declaration of independence from Spain and the following war at the beginnings of the 19th century,
the nation required foreign currency for the organization and defence of the young State. Then, the
Coquimbo region and in particular the Elqui basin provided its silver, copper and gold resources, that
contributed to a rapid mining development and therefore of incomes to the Country. Also, the local
government contributed with technical education and private investors, like C. Lambert, who brought
advanced technology, as the reberveratory furnace for copper smelting installed al La Serena (Las
Compañías). Among the principal deposits of the Elqui basin mined by the 1830`s were those of
Arqueros (silver), Lambert and Talcuna (copper and manganese), and Andacollo (gold and copper).
Silver mining declined during the 20th century, although Arqueros (Ag, Cu) and Condoriaco (Ag, Au)
remain as important exploration targets. In exchange, Lambert, Talcuna and Andacollo are still active
mining districts. Also, a new Au, Cu, As-rich: El Indio – Tambo, well known for its high Au grades
(locally, up to several kg/t of gold), was developed in the 1970`s. However, it has a short life and
went to a closure stage in the early 2000`s. All of these deposits are related to hydrothermal activity in
plutonic-volcanic calc alkaline complexes of Cretaceous (Lambert, Talcuna and Andacollo),
Cretaceous to Tertiary ( Arqueros and Condoriaco) and Upper Tertiary (El Indio-Tambo) age. Briefs
descriptions of these mining districts follows.
Lambert District (Aguirre and Egert, 1970 ; Emparán and Pineda, 2000): The district includes a
number of Cu, Au, Fe and Mn deposits of different types and morphologies (veins, stratabound, skarn,
disseminated, IOCG, etc) around 29º35’S / 71º07’W. They are emplaced in Lower to Middle
Cretaceous volcanic and sedimentary series lying as roof pendants over slightly younger intermediate
intrusive granitoids. Although Lambert was an important district in the middle 1800`s, in particular its
Cerro Brillador copper mine (Fig. 16A), present mining activity is rather marginal. However, its San
Antonio IOCG skarn deposits are interesting targets for exploration companies. Also, a
hydrometallurgical facility, located in the Quebrada Santa Gracia gulch (Fig. 16B), on the central part
of the District, is processing copper minerals for the elaboration of industrial copper salts.
B
A
Figure 16: Views of Cerro Brillador (A) and the Santa Gracia gulch (B)
Arqueros and Condoriaco Districts (Emparán and Pineda, 1999; Ruiz, 1965): Arqueros (around
29º 50´S / 70º 56`W) gather several NW trending silver deposits located in a Lower Cretaceous
volcanic-sedimentary formation. Although no significant silver mining is presently performed in the
District, transitional Cu-Ag veins and stratabound Cu ore-bodies located close to the neighbouring
Talcuna district are being developed. Condoriaco (around 29º 54`S / 71º 00`W) is a vein-type Ag – Au
district, that also includes some disseminated orebodies. Hydrothermal alteration is more intensive and
extensive in comparison to Arqueros, and explosive volcanic activity, including the development of a
huge (30 x 20 km) nested caldera and of ignimbritic flows, characterize this probably Lower Tertiary
district. An active mining exploration is carried out in this district.
13
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Talcuna District (Boric, 1985; Oyarzún et al, 1998): Although the Talcuna district has been mined
since the early 1800`s, its real magnitude is still unknown. However, according to the results of
present drilling campaigns, it still hosts several tens of million tons of copper ores about 1% grade.
The Talcuna deposits include vein and stratabound copper ores as well as stratabound manganese
bodies. The deposits are on the mountains flanks of two gulches: Quebrada Marquesa and Quebrada
Las Cañas, around 29º 53´S / 70º 55´W. Like the other districts of the basin (with the exception of El
Indio-Tambo, located on the Andean heights), Talcuna is on the Coatal Cordillera domain (Fig 17).
Figure 17: Landscape views of the Talcuna district and the existing mining operations
Its deposits are hosted by the Quebrada Marquesa Middle Cretaceous formation, where volcanic
conglomerates are dominant. Copper mining is performed by underground methods and its sulphide
mineral are concentrated by the flotation process, at a present rate of about 3000 tons per day,
considering the four mining companies operating on the district. About 1.5 Mt of tailing deposits of
the flotation process are still in the narrow Marquesa gulch (Mena, 2002), and an unknown amount of
old tailings has been removed by slurry flows during the intense precipitations related to El Niño
episodes (Fig. 18). Also, design or operational failures have been responsible for contamination of the
irrigation system of the Elqui river basin (Galleguillos, 2004). This fact is a reason to worry about,
considering that the Talcuna district tails have significant amounts of PbS (galena) and that the Elqui
river sediments are already exceptionally rich in Cu (about 0.1% in its fine fractions; Oyarzún et al,
2003). One of the mining companies is processing its Cu ores at a facility located some km west of the
Marquesa gulch, on the northern slope of the Elqui river valley.
14
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 18: Flash flood events associated with El Niño years that have provoke tailing removal and
transportation
Andacollo District (Reyes, 1991; Oyarzún et al, 1996): A very old mining district (placer gold was
already mined in pre- Hispanic times), Andacollo is rather independent of the Elqui basin, and it is
connected to La Serena – Coquimbo by a different access. However, the District, located around
30º14’S / 71º 06’W, at a medium altitude of 1030 m, is related to the Elqui basin in two ways. First,
the relatively high Andacollo basin partly drains to the Elqui watershed by the Los Negritos gulch
(Fig. 19), which is connected to the El Arrayán gulch, a southern affluent to the Elqui river. Although
both gulch have no permanent water flow, the fact that many tailing deposits are located in the Los
Negritos course represent a pollution risk by slurry floods during intense precipitation episodes related
to El Niño (Fig. 19). The second relationship concerns to the role played by the La Cantera – Pan de
Azúcar basin, a tectonically controlled N-S trending valley which has a thin alluvial cover and perform
as an aquifer for local farmer needs of irrigation and drinking water. Also, it provides drinking water
for the Andacollo town, and process water for copper and gold mining of this mining district.
However, the basin also receives water from the Elqui River via the Bellavista irrigation channel.
Therefore, this basin connects, in hydrological terms, Andacollo with the Elqui watershed (Fig. 20).
15
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
A
B
D
C
Figure 19: A: General overview of the location of the Andacollo district (red circle) with respect to the
Elqui Basin. B: Schematic representation of the relation between the Andacollo area and the Elqui basin
through the Los Negritos-El Arrayán drainage system; C: Los Negritos gulch showing abandoned tailing
deposits; D: El Arrayán overview.
16
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
A
B
Figure 20: A: Google earth image showing the location of the Andacollo district (red circle), the Pan de
Azúcar agricultural basin (green circle), the Elqui river (blue segmented line), the Bellavista channel (light
blue segmented line) and the access road to Andacollo (black segmented line); B: Agricultural activity in
the Pan de Azúcar land.
The Andacollo district’s history of “up and down” gold and copper small scale mining changed in the
1990`s, when two medium size operations took the control of the district: Dayton (gold) and Carmen
de Andacollo (copper). Both had in common the amount of the economic reserves to be mined (about
30 Mt), the rather low grade of the ores (0.7 % Cu in Carmen, 1 g/t Au in Dayton), the production rate
(about 20000 t / day) and the time horizon of the projects (around ten years in both projects). The
Andacollo copper deposits are distributed in the eastern part of the district, directly W and SW of the
town, and are considering parts of porphyry copper system about 100 Ma in age. Gold deposits of the
vein and “manto” types are directly west of the copper ones, although the relationships between the
copper and gold pulses are not well understood. Also, both districts are hosted by the Quebrada
Marquesa formation (that also hosts the Talcuna district). Both Dayton and Carmen deposits are mined
through medium-sized open pit operations, and use hydrometallurgical processes (Fig. 21): sodium
cyanide for the gold ores (Dayton) and sulphuric acid followed by SX-EM for the copper ones
(Carmen).
17
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 21: General overviews of the Andacollo mine activities
Dayton closed mining operations by 2000, but last years new highs in gold prices promoted its reopening in 2006. For Carmen, that should have finished its mining activities by 2008 – 2009, current
copper prices foster the approval of the Hipógeno project (underground extension). This is a high
magnitude project, aimed to mine some 400 Mt of primary very low grade ore (0.4% Cu), with a time
horizon of 20 years, for which ca. 400 l/s will be extracted from the La Cantera - Pan de Azúcar basin.
This fact has generated serious concern among the local farmers, which have reasonable doubts
regarding the capacity of the aquifer to continuously deliver such a water volume. This project , which
implies a change from the present bio-hydrometallurgical heap leaching process to concentration of
sulphide minerals by flotation, will generate a huge, extended, tailing deposit south of the deep open
pit, a likely source of contamination by particulate materials in the future, considering the prevailing
winds in the Andacollo basin.
El Indio - Tambo Au-Cu-As district (Jannas et al, 1999; Oyarzún et al, 2004): This district,
located at the Andean head of the basin, at an altitude above 4,000 m, is directly connected to the Rio
del Toro, and therefore, to the Elqui river. El Indio is a vein-type, epithermal Miocene deposit,
presenting intermediate to advanced hydrothermal alteration (Figure 22). Tambo, about 10 km SE
from El Indio is a disseminated deposit associated to sulphate-rich, advanced argilic alteration.
18
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 22: General overview of the El Indio district
Famous by its high Au grades, the ore is also rich in enagite (Cu3AsS4). Active from the mid 1970s
until 1999, the mining company of El Indio initiated a closure plan in 2003. However, the district,
which is located on a belt of hydrothermal alteration zones, has been a natural source of acid drainage,
for at least 10,000 years, and delivers important contents of As, Cu, Zn, Fe and SO42- to the Rio del
Toro water and sediments, which are largely in excess of the Chilean standard for irrigation water
(Galleguillos, 2004). Although the closure plan actions have been effective in decreasing the As water
content, Cu has increased and pH decreased, suggesting an intensification of the acid drainage
generation (AD) process (Galleguillos, 2004). Taking into account that the El Indio underground mine
has about 130 km of tunnels and that a large groundwater flow circulates by the mine galleries,
intensification of the AD generation process is foreseen as a disturbing possibility (Guevara et al.
2006; Oyarzún et al., 2007). Furthermore, the district host ca. 22 Mt of tailings (El Indio) and ca. 12
MT of heap leaching wastes (Tambo). Given the already mentioned structural and lithological
characteristics of the host rocks, this situation demands a long term monitoring of the area, in
particular water quality.
Other deposits and mining wastes on the Elqui Watershed. In addition to the main mining
districts (and mining operations) mentioned, a large number of ore deposits (Cu, Ag, Au ores, with
minor contents of Zn, Pb, As, etc.) were mined during the 19th and 20th centuries. Most of these
former operations, and the associated metallurgical facilities, were located in the western half of the
watershed. These operations have left a heritage of barren and low-grade material, tailings of the
sulphide concentration processes, acid (Cu) and alkaline cyanide (Au) bearing leach pile wastes, and
minor residues of mercury related to gold recovery. Also, the cavities left by mining collect
groundwater, enhancing water-rock interaction, the transport of soluble salts containing heavy metals,
and in some cases, the generation of acid drainage (Oyarzún et al. 2003)
2.1.8 Water requirements
Nationwide, total water use amounts ca. 2300 m3/s, being 30% for consumptive use and the
remaining 70% for non consumptive use, mainly hydro electrical power generation. Among
consumptive use, agriculture represents the main demanding sector, with ca. 80%, followed by
industry (7,9%), mining (6,8%) and drinking water (4,4%) (Salazar, 2003). For the Coquimbo Region,
this situation slightly changes: Irrigated agriculture demanded by 2003 ca. 95% of the total water use,
mining and drinking water production required each one 2,5%, and industry use was negligible.
However, it must be pointed out that these figures may have changed or will change to some extent by
the existence of Los Pelambres mining activity in the Choapa basin and the near expansion of the
Carmen de Andacollo Cu Project in the Elqui Province.
Table 1 shows the average net water use for different economic areas in the Elqui basin.
19
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Table 1. Consumptive water demand for the Elqui river basin
Demanding Activity
Demanded Discharge (m3/s)
Volume (m3)
Agriculture
4,320
136.859.933
Mining
0,101
3.185.136
Industry
0,062
1.955.232
Drinkable water, urban
0,250
7.884.000
Drinkable water, rural
0,039
1.229904
Source: CAZALAC-RHODOS (2006)
However, given high inefficiencies still existing in the systems of distribution and application of
water, actual required amounts are higher, as shown in table 2
Table 2. Actual required amount of water by different sectors given the inefficiencies.
Demanding Sector
Required Discharge (m3/s)
Agriculture
13,584
Mining
0,216
Industry
0,062
Drinkable water, urban
0,831
Drinkable water, rural
0,141
Source: CAZALAC-RHODOS (2006)
These figures can be explained and further detailed as follows:
- Agriculture: The Elqui river watershed has currently ca. 23.000 cultivated ha, 25% upstream the
Puclaro reservoir and 75% downstream, whereas ca. 91% of the total cropped land is downstream La
Laguna reservoir. Thus, only the Claro sub-basin is not regulated. The agricultural water demand is as
follows: 5% at the Estero Derecho, 27% in the Elqui system upstream Puclaro, and 68% in the Elqui
downstream Puclaro, including the Pan de Azúcar sector. The 75% of total cultivated land existing
downstream Puclaro uses only 68% of the total water use for agriculture in the basin. Indeed,
downstream Puclaro, the main crop corresponds to horticultural and annual crops, whereas upstream
Puclaro the main crop is vineyard. With ca. 31% of the surface with mechanical irrigation (drip,
micro-sprinkler), this basin tends to be relatively high efficient in terms of water use for agriculture.
There is an estimated re-use of 2.5 times of the water for agricultural purposes. This mean that “one
single drop of water” is used at least twice (in two different locations) throughout the basin. This is
possible due to surface water returns and percolation from the irrigated areas towards the alluvial
streambed.
- Drinking water: The water company has water rights for ca. 2549 l/s, being 2254 l/s available for
Coquimbo and La Serena. Nevertheless, the cities use, in average, only 33% of this amount, which is
supplied almost entirely by surface water. The company (Aguas del Valle) also has groundwater rights
that are used only during summer or dry periods. Regarding rural water supply (Comités de Agua
Potable Rural, APR), a consumptive use of 39 l/s in total is estimated, along with groundwater use of
ca. 140 l/s. This allows average water delivers of 40-80 l/hab/day.
20
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
- Mining: The historical main user of water was the El Indio mine, now in closure stage. The current
use by currently active mining companies should be around 216 l/s, however there is still a high level
of uncertainty regarding actual water use by mining companies in the basin, since they are resilient to
give public information. Also, current estimations will certainly increase with current prospects and
the expansion of the Andacollo Cu mining activity (Carmen de Andacollo Company) which will
withdraw ca. 400 l/s from the Pan de Azúcar aquifer.
- Industry: The industry sector (as well as agro-industry) has rights for 246 l/s through the watershed.
Despite further information, it can be estimated the consumptive use to be 25%, i.e. 60 l/s.
In terms of economic efficiency in the use of water, clearly mining is the economic sector that uses
water with high financial efficiency, with nearly US$ 1-100/m3 (the wide range depends on the
international value of metals. The given figures are calculated for Cu prices of the range US$ 13/pound). For the agricultural sector, economic benefits range between US$ 0,1-2/m3 of consumed
water. Water market is less active that that of the Limarí basin towards the south, since users have had
enough available water. According to Cristi (2000), only 17% of the total water rights have been
traded in the period 1981-2000.
2.1.9 Socioeconomic characterization
Given that socio-economic information at the Province (Elqui) level is not easily accessed, the
following paragraphs present socio-economic features of the Coquimbo Region. While the Elqui basin
(almost coincident with the Province) host the major part of the inhabitants of the region (represented
by the La Serena-Coquimbo conurbation), the main agricultural activity occurs in the Limarí Province
(basin), whereas the main mining activity of the region takes place in the Choapa Province represented
by the Los Pelambres deposit. Thus, the interpretation of the following information must be done with
these mentioned elements in mind. On the other hand, the given information is highly updated (2007)
which makes it an important base information to considers.
With a total population of 603.210 inhabitants (more than half of it concentrated in La SerenaCoquimbo), the average population density of the Coquimbo Region reaches 14,86 hab/km2.
Approximately 78% of the population lives in urban areas, whereas 22% resides in rural areas. The
Region exhibits steady increments in the number of employed people, with unemployment rates of
7,5%, lower than the national average of 8,9%. The most dynamic sector regarding employment
increment has been services, followed by agriculture and fishing. However, agriculture is still the main
economic sector in terms of the total of persons employed, with ca. 50,000. On the other hand,
mining, despite of being a major contribution to the Regional Gross Income Product (PIB in Spanish),
just holds 4,3% of the regional employment rates. Poverty levels were 21,7% by 2003.
The Coquimbo Region Gross Product Income have shown a sustained increment with an annual
average rate of 4,3% for the period 1960-2005. Mining is the economic sector that contributes the
most to the GPI, ca. 17%, followed by Personnel Services (15%) and construction (15%). On the other
hand, fishing is the less important activity with only 1%.
The Coquimbo Region is characterized by a productive diversification, which is reflected in the
number of companies and the sales levels. The economic sectors that exhibit an important number of
companies are Trade, Services, Transport and agriculture. However, this does not translate into the
amount of sales. Indeed, the mining sector participates in more than 15% of the sales whereas it has
only 1% of the companies. This do translates however into Coquimbo Region exports, being 89%
coming from the mining sector (US$ 2.361.636.837), and only 10 and 2% coming from agriculture
and fishing, respectively. Although mining explains to some extent the increase in exports from the
Coquimbo Region in the last years, both the agricultural and fishing sectors have shown a rather good
performance as well, with average increase rates of 29 and 22% respectively.
21
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Table 3. Coquimbo Region Exports Evolution by Sector
Year
Fishing
Agriculture
Mining
Others
2001
28
92
553
24
2002
32
104
626
28
2003
54
175
1056
47
2004
55
232
1543
33
2005
62
252
2362
34
With regards to mining sector, it is possible to identify two sub sectors in the Coquimbo Region:
Metallic mining (Cu, Au, Ag, Mo, Pb, Zn, Fe, Mn) and non-metallic mining (nitrate, iodium, lithium
carbonate). The total production attained (2006) 4.017.313 tons, ca. 13% of the national production.
From the total of mining companies (246 registered in 2004), there are three types: small scale (90%),
medium scale (19%) and large scale mining companies (3%)
2.2
Pressure and Issues
2.2.1 Governmentally Supported Development Programs
Currently, both for the Coquimbo Region and the Elqui basin, two governmentally supported
programs are worth to be mentioned. The former is related with the initiative to transform Chile into a
world wide leader food producer country, a country-wide initiative that have been focused for the
Coquimbo Region, and therefore the Elqui basin, to transform it in an important producer of
“Mediterranean diet food” (grapes, cheese, olives, fresh fruits, fish and seafood) (Fig. 23). The second
initiative is to attract, to the Coquimbo Region, 1 million tourists by 2010, taking advantage of the
natural beauties and pristine environment still existing in the Coquimbo region and of course in the
Elqui Valley. These two governmentally supported mid-term initiatives rely on the important
characteristic of a safe and unpolluted environment, where mining is envisioned as a negative and
even not desirable economic activity.
Figure 23: Webpages showing nation-wide and local government efforts to transform Chile into a worldwide leading food producer country
22
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
2.2.2 Current Scenario for Science and Technology Development
Benefited by the economic growth and in particular for the recently approved specific fee to the
earnings of the mining industry and sector (Royalty), the Chilean government will be strongly
supporting both scientific research and innovative technological solution development in the country
in the coming years. Thus, a special consulting board, the “Consejo Nacional para la Innovación y
Competitividad” (http://www.consejodeinnovacion.cl /cnic/cnic/web/portada.php) has been rather
recently established (2005), and this effort has been fostered also at the Regional level by the creation
of the Regional Offices for Productive Development (Agencias Regionales de Desarrollo Productivo,
http://www.corfo.cl/index.asp?seccion=1&id=2807). Specifically in the Coquimbo Region, two
research and scientific (but independent) centres were established in 2003, the Centre for Water
Resources for Latin America and the Caribbean, CAZALAC, a UNESCO-related institution
(www.cazalac.org) and the Centre for Advanced Research in Arid Zones, CEAZA (www.ceaza.cl),
funded by the Coquimbo Region Government and the National Commission for Scientific and
Technological Development (CONICYT). Through these Centres, and supported by the Coquimbo
region Government, several collaboration attempts have been promoted with research and official
(governmental) institutions of USA and Europe. Thus, there is, besides CAMINAR, currently ongoing
collaboration with the International Research Institute for Climate Prediction (IRI) of the University of
Columbia (http://portal.iri.columbia. edu/portal/server.pt), as well as political collaboration between
the Coquimbo Region and the L´Herault Department of France. Scientifically, this agreement links
CEAZA and Agropolis. Within this framework, the Junta de Vigilancia del Rio Elqui, the main private
water users organization of the basin, has been trying to promote activities such as “River Contract”
(Contrato de Río) and the “Water House” (Casa del Agua), oriented towards a sustainable
management of water resources at the Elqui river basin (Mena, 2002).
2.2.3 Water quality monitoring and secondary water quality regulations
The major anionic components in waters of the Elqui basin is sulphate, followed by bicarbonate, and
then by chloride. Typical average ranges are 80 – 300mg/l for sulphate (although rise to an average of
880 mg/l in Río Toro), 55 – 180 mg/l for bicarbonate (although an average of only 1.3 mg/l is found in
Río Toro), and 6 to 136 g/l Cl, the upper average value corresponding to an Andean river and the
higher to the Elqui river at La Serena, that is close to the principal chloride source: the sea. Except for
the acidic Toro river (pH average 4.9), al pH averages are between 7.4 and 8.1, that is, slightly alkaline
as correspond to the arid conditions that prevail in the basin. Regarding major cations, typical ranges
are 30 – 90 mg/l for Ca, 10 – 21 mg/l for Mg, 6 – 25 mg/l for Na and 0.5 – 4 mg/l for K. The Toro
river is an exception, presenting averages of 200 mg/l Ca, 45 mg/l Mg, 50 mg / l Na and 12 mg/l K.
This is a logical consequence of the strong rock leaching produced both as a result of hydrothermal
alteration and of the oxidation of pyritic ores (that generate sulphuric acid). High Cu, Zn, As and Fe
contents in water are also related to the influence of El Indio district. Cu and Zn contents attain about
10mg/l (Cu) and 2 mg/l (Zn) in the Toro river water, but decrease to Cu averages of 1,7 mg/l (Turbio
river) and 0.8 mg/l (Elqui river). Zn also decrease to 0.4 and 0.2 mg/l respectively, as a consequence
of both mixing with Cu and Zn poor water (La Laguna, Incaguaz and Claro rivers) and by Cu and Zn
transfer to the sediments, related to the rise of pH values. As contents are also direct consequences of
the presence of El Indio district, and decrease from 0.7 mg /l in the Toro river water to 0.01 mg/l in the
final course of the Elqui River. Fe contents also decrease from 22 mg/l in Toro river to 0.5 mg/l (final
course of the Elqui river) (Galleguillos, 2004; Oyarzún et al, 2003, Strauch et al, 2006).
The local office of the Chilean Water Authority, the DGA (Dirección General de Aguas), performs a
systematic monitoring of water quality since 1991 considering about 30 physical and chemical
parameters, although there are some gaps on the historical records (i.e., not necessarily all of them
have been always determined). Surface waters are sampled at 13 locations throughout the watershed
(Fig. 24), whereas there are five groundwater sampling wells in the Elqui Province; two of them lies
within the catchment’s limits, concentrated in the lower parts of the basin (near to the Ocean).
23
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 24: DGA and CONAMA surface water and groundwater monitoring and sampling network in the
Limarí Province.
Also, the ongoing process of formulation of environmental quality secondary regulations (described
below) carried out by the Chilean Environmental Commission (CONAMA) in several watersheds of
the country, enhances the importance of having suitable and reliable methodologies to characterize
hydro-geochemical systems and the controlling factors and mechanism that determine water quality.
Indeed, in 2006, the Executive Director of CONAMA approved the preliminary version of the
Environmental Quality Secondary Regulations for the Protection of Inland Waters in several
watersheds in the country, including the Elqui River basin. Thus, for the Elqui River watershed, the
preliminary regulation was formulated in February 2, 2006, and is currently almost finished. In
particular, its main objective is to “protect, keep, and recover the inland, surface water quality of the
Elqui River watershed, in order to secure the use and availability of the water resource, the protection
and conservation of the aquatic communities and the ecosystem, maximizing environmental, social
and economic benefits”. Also, it is stated that “this regulation will allow the protection and
conservation of the current water quality avoiding the future impairment of the resource, ensuring an
acceptable level in accordance with the available and scientific criteria” (CONAMA 2006). Up to now
only surface waters are included in the proposed regulation, whereas groundwater is ignored.
2.2.4 Climate change
Although subjected to high uncertainties yet, calculations based on global climatic models, assuming a
two-fold CO2 concentration increase, indicate the following scenarios for the Coquimbo Region: (1) A
warming of 2ºC to 3ºC during the second decade of the current century; (2) a 10% increase in
precipitation in mountains and foothills, with 20 to 25% decrease in liquid precipitation; (3) A flow
increase in the short and/or mid term, due to the melting of snow and ice reserves (CONAMA, 1999;
Cepeda et al. 2004). In particular for the upper Elqui river basin, a preliminary assessment performed
by Souvignet (2007) estimated that local temperatures are expected to rise in the region, whereas
precipitations will decrease. However, minimum and maximum temperatures will increase with a
faster rate in high altitude areas with an increase ranging from ca. 1.8°C to 3.5°C by 2059.
Furthermore, lower altitudes areas may expect an increase from ca. 0.85°C to 1.8°C by the end of the
century. Areas above 3000 m a.s.l. would encounter warmer and longer winters with a dramatic
24
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
decrease of over 70% of icing days (Tmax<0°C). As for precipitation, both scenarios considered in the
Souvignet (2007) study (A2a and B2a SRES) return a diminishing trend of ca. 25%, though the A2a
scenario results show a faster decrease rate. In addition, the region expects an augmentation of dry
spell in middle altitudes areas during the six decades. Results indicate strong inter-seasonal and interannual perturbations in the region. Regarding flow simulations, by 2059 both A2a and B2a scenarios
return net variations in monthly and annual flows. Moreover, fluctuations of flows between future
decades underline an increase of the already high sensibility of the region in term of hydrological
responses to climatic variations. Hence, the hydrology of the Elqui valley is likely to be strongly
affected by climate change. Moreover, current evidence already indicates changes in some climatic
parameters. Indeed, the temperatures and relative humidity show a trend towards increases for a 100
year database for the La Serena-Coquimbo area, whereas the average precipitation has been
dramatically reduced (Cepeda et al. 2004). Regarding the latter, the 30-year running average has
decreased from 170 mm in the early XX century to values under 80 mm currently (Santibañez, 1997;
Novoa and Lopez, 2001). This represents a 100 mm/year movement of the isohyets towards south,
which has caused a desertification of ca. -0.7 mm/year. Thus, what is clear is the high vulnerability of
transition zones such as the Elqui basin, placed between the arid northern area and the moderate humid
southern zone, where an extremely fragile equilibrium exists in terms of water availability vs. water
demands, considering both quantity and quality of this natural resource.
2.2.5 Integrated watershed management
The concept of integrated development of basins establishes that every action carried out on a
delimited physical territory will affect the surroundings, and therefore the growth and development of
a territory must be harmonic with natural resources. Whether it is an industrial, municipal or
agricultural demand, it must necessarily be evaluated by the actors and users of the basin. Here are
included, among others, technical, legal, juridical and administrative organisms.
Integrated management of basins is a group of actions that determine the management of a basin,
originated from the base of the territory in question through the multi-participative work of users to
protect, for example, the water quality and the natural balance of water ecosystems. The concept of
integrated management is born with a strong decentralization and local valorisation component since
every basin is specific.
Even though basin integral management is a new concept in Chile, such concept still lacks of a
constitutional and legal frame, and it is addressed, for the time being, in an extremely fragmented way,
with legislative adjustments only through the water code (Mena 2002; Oyarzún et al. 2007). The
possibility to apply this discipline not only would allow to achieve territorial planning and zoning, but
also to comply with the international compromises and demands acquired by the country. Thus, even
if there is not a clear legislation about this issue in Chile, there are some initiatives and debates around
the integral management of water resources at the level of hydrographic basin, especially after the
90’s. Nevertheless, in practice, evidence and experience are rather scarce. The DGA is the State
organism that has implemented the most important actions towards this goal since 1994. The
instruments developed and used include the Directive Guidelines (Planes Directores), for the period
1997-2003, and the support of the basin organisms and the public institutions. In the case of the Elqui
basin, the DGA supported the design of a Director Plan, which due to the lack of economic support
was not complete.
However, these initiatives remain as proposals without making significant progress, with partial or
sectorial achievements that are far away from the concept of integrated basin management, mainly
because of financing problems and lack of the companying legislation. Recently, CONAMA has been
also addressing the subject of basin management initiating a National Integrated Basin Management
Strategy, which is currently on a design stage and evaluation of the legal, economical, social,
environmental feasibility (Fig. 25). Regardless the results of this particular initiative, it is clear that an
effective integrated management plan will have to consider elements beyond purely technical aspects.
25
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 25: CONAMA´s efforts toward Integrated Watershed Management.
2.2.6 Growing Economies and International Forcers
Despite substitution of copper in a number of specific uses, this metal currently stands as a key basic
material for the industry. The relatively unexpected industrial booms in China and India have occurred
at a time of low copper supply and reserves. Given the low copper prices during the 1980s−1990s,
these years were poor in ore deposits discovery and development: mining companies keep exploration
at a minimum when metal prices are low. Therefore, a considerable pressure has developed on the
booming Chilean (copper) mining, which already experiments a serious shortage of water resources,
both for its present needs and for its expansion and new projects. This pressure could eventually affect
two rather feeble sectors in Chile, the environment and the small scale, low income farming in the
northern regions. This is not different from the specific situation at the Elqui, where these types of
conflicts are starting to rise.
2.2.7 Current and Prospective Problems
As it has been previously stated, there are no major problems regarding water and mining currently in
the Elqui basin yet. Major difficulties have risen in El Niño years due to the flash flood and transport
of abandoned tailing deposits and wastes (Marquesa Gulch) and by the permanent worries of the
agricultural sector and authorities due to contamination problems provoked by mining activities. Also,
non El Niño-related episodes have occurred even recently as consequence of wrong or irresponsible
practices (Fig. 26).
26
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 26: Example of a recent mining related environmental problem (taken from El Tiempo”
newspaper, Week of 6-12 July, 2007)
Recent developments allow us to infer that the mining activity will be under increasing stresses for the
use of water and the relationship between this sector and other important economic and social
activities developed in the Elqui basin.
First, the important endeavour carried out by the Chilean government to transform Chile into a worldwide food producer leading country, along with the increasing quality requirement of foreign markets,
will likely add additional pressure on the mining sector, regarding processes used and waste
management, when presented for approval of CONAMA. Also, if the high prices of metals (Au, Cu)
remain for the coming years, there will be an increasing interest in mining exploration and the start of
new projects or the expansion of current ones. A particular case is represented by the Pan de AzúcarCarmen de Andacollo situation. Although there have been attempts to establish a dialogue forum in
order to obtain an agreement and a sustainable development of the area, this has been unsuccessful,
and the situation is currently at the legal level (Fig. 27).
27
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 27: Newspaper information regarding the Pan de Azúcar-Andacollo rising conflict (left news dated
from the week 27 April-3 May, 2007; right information is for the week of 25-31 January, 2008).
Finally, the case of the El Indio mine and its closure plan has shown that acid drainage generation is a
problem that extends way beyond the closure of the mine. This type of situations, which have been
already detected in the Elqui basin (Galleguillos et al. In press) and that are going to be further studied
within CAMINAR, may serve as a suitable example and general guideline for nearby regions such as
the Atacama region where the Pascua Lama deposit is located, given some similarities between Pascua
Lama and El Indio in terms of hydrothermal alteration of the rocks and the high levels of rock
fracturing existing (Fig. 28).
28
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
Figure 28: General overview of the geological characteristics of the Pascua Lama deposit, Atacama
Region.
29
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
3 CONCLUSIONS
The Elqui river watershed, as well as the Coquimbo Region as a whole, is particularly interesting in
terms of its fragile balance of water resources, water availability and demands, being a transition zone
between the arid Northern Chile and the wetter Central and South Central Chile. This fragile balance
may be broken if current estimations of climate change and their effects on precipitations and snow
melting rates are correct.
Several mining operations are carried out in the basin and in close areas and important conflicts
between different economic sectors, in particular agriculture and mining, are starting to rise. Also,
there is an important mining district on the headwaters of the basin, El Indio, which initiated a
voluntary closure plan. Within this framework, mining is competing for water resources with other
agricultural sectors, and these other sectors are raising increasing levels of awareness regarding water
availability, both in terms of quantity and quality. At the same time, several international
collaborations efforts related with water assessment and water management at the basin scale are
currently ongoing in the watershed and in the Region. Thus, this North Central arid zone realm may
constitute a favourable “natural laboratory” for the improvement of watershed management topics in
arid zones with mining activities.
30
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
4 REFERENCES
- Arumí, J.L., Oyarzún, R. 2006. Groundwater in Chile (in Spanish). Boletín Geológico y Minero 117,
37-45.
- Boris, R. (1985) Geología y yacimientos metálicos del Distrito Talcuna, IV Regíon de Coquimbo.
Revista Geológica de Chile, Santiago, 25-26: 57 -75.
- CAZALAC-RHODOS. 2005. Aplication of methodologies to determine the water use efficiency .
Case of study in the Coquimbo Region. Elqui River basin diagnostic (in Spanish). Unpublished
Report. 261 pp.
- CAZALAC, 2006. Guía metodológica para la elaboración del mapa de zonas áridas, semiáridas y
subhúmedas secas de America Latina y el Caribe. CAZALAC-UNESCO. Documentos Técnicos del
PHI-LAC, Nº 3.
- Cepeda, J., M. Fiebig, H. Morales, and S. Salas, 2004. Description of the Elqui River Basin. IACC
Project Working Paper No. 2, Universidad La Serena, Chile.
- Cepeda J. 2006. Geoecología de los Andes desérticos. La Alta Montaña del valle del Elqui.
Ediciones Universidad de la Serena, 551 pp.
- Cepeda J & J Novoa (2006). La cordillera altoandina del valle del Elqui. In: Geoecología de los
Andes desérticos. La Alta Montaña del valle del Elqui. Ediciones Universidad de la Serena, 1.2: 41-63.
- CONAMA, 2005. Anteproyecto de la norma secundaria de calidad ambiental para la protección de
las aguas continentales superficiales de la cuenca del río Esquí. Republica de Chile.
- CONAMA, 1999. Primera Comunicación Nacional bajo la Convención Marco de las Naciones
Unidas sobre el Cambio Climático. Comisión Nacional del medio Ambiente.
- CONAMA, 2006. Preliminary Project for the Secondary Environmental Quality Regulation for the
protection of inland surface waters of the Elqui River watershed (in Spanish). 10 pp. Available at
http://www.conama.cl /portal/1255/article-34316.html. Acceded on March 6, 2006.
- Cristi, O., Trejo, A. 2003. Mercado del agua para irrigación y uso urbano: Una aplicación a la cuenca
del rio Elqui, Chile. Informe Preliminar, World Bank-Netherlands Water Partnership Program
(BNWPP), Washington DC.
- Emparán, C and Pineda, G. (1999) Area Condoriaco – Rivadavia, Región de Coquimbo. Mapa
Geológico Nº 12, Escala 1: 100.000. SERNAGEOMÍN, Santiago.
- Emparán, C. and Pineda, C. (2000) Area La Serena – La Higuera, Región de Coquimbo. Mapa
Geológico Nº 18, Escala 1: 100.000 SERNAGEOMÍN, Santiago.
- Galleguillos, G. 2004. Mining activities and hydraulic works effects over the water quality of Elqui
River and its tributaries (in Spanish). Graduation Project, University of La Serena, 247 pp.
- Galleguillos, G., Oyarzún, J., Maturana, H., Oyarzúnun, R. Retención de arsénico en embalses: el
caso del Río Elqui, Chile. Ingeniería Hidráulica en Mexico. In Press.
- Guevara, S., Oyarzún, J., Maturana, H. 2006. Water geochemistry of the Elqui River and its
tributaries in the period 1975-1995: natural factors and effect of mining activities on its Fe, Cu, and As
contents (in Spanish). Agricultura Técnica 66, 57-69
- Habit, E., Dyer, B., Vila, I. 2006. Estado de conocimiento de los peces dulceacuícolas de Chile.
Gayana 70 (1): 100-113.
- Higueras, P., Oyarzun, R., Oyarzún, J., Maturana, H., Lillo, J., and Morata, D. 2004. Environmental
assessment of copper–gold-mercury mining in the Andacollo and Punitaqui districts, northern Chile.
Appl. Geochem. 19: 1855-1864.
- Instituto de Economía Aplicada Regiona, Universidad Católica del Norte. 2007. Evolución del
Desarrollo Productivo de la Región de Coquimbo. Resumen Ejecutivo.
31
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
- Jannas, R.R., Bowers, T.S., Petersen, U., and Beane, R.E. 1999. High –sulfidation deposit types in
the El Indio district, Chile. Society of Economic Geologists, Special Publication 7: 27-59.
- Kalthoff, N., Bischoff-Gauss, I., Fiebig-Wittmaack, M., Fiedler, F., Thürauf, J., Novoa, E., Pizarro,
C., Castillo, R., Gallardo, L., Rondanelli, R. 2002. Mesoscale wind regimes in Chile at 30º S. Journal
of Applied Meteorology 41(9), 953-970
- Kalthoff, N., Fiebig-Wittmaack, M., Meiβner, C., Kohler, M., Uriarte, M., Bischoff-Gauβ, I.,
Gonzales, E. 2006. The energy balance, evapo-transpiration and nocturnal dew deposition of an arid
valley in the Andes. J. Arid Environ. 65, 420-443
- Lecomte, K.L., Pasquini, A., Depetris, P.J. 2005. Mineral weathering in a semiarid mountain: its
assessment through phreeqc inverse modeling. Aquatic Geochemistry 11, 173-194.
- Llanca, J.C., Miranda, E.E. 2003. Groundwater studies in the Elqui River watershed (in Spanish).
Civil Engineering Graduation Project, University of La Serena, La Serena, Chile, 203 pp.
- Luengo, P., Oyarzún, R., Oyarzún, J., Alvarez, P., Canut de Bon, C. Aguas subterraneas en macizos
rocosos fracturados: su utilizacion en zonas rurales montañosas del centro norte de Chile. VIII
Congreso Latinoamericano de Hidrología Subterránea Septiembre, 2006 – Asunción, Paraguay.
- Mena, M. 2002. Gestión integrada de los recursos hídricos en la cuenca del Elqui, IV Región, Chile.
Tesis Ing. Civil, Universidad de La Serena, 140 pp.
- Novoa, E. y López, D. 2001. IV Región: EL escenario geográfico-físico. En Squeo, F., Arancio, G.,
Gutiérrez, J. (Eds.). Libro Rojo de la Flora Nativa de los Sitios Prioritarios para su Conservación,
Región de Coquimbo. pp. 13-28.
- Osorio, R., Cabeza, R., Reyes, H., Alvarez, P., Koné, T. 2006. Humedales altoandinos de la IV
región. In: Geoecología de los Andes desérticos. La Alta Montaña del valle del Elqui. Ediciones
Universidad de la Serena, 3.1: 153-239:
- Oyarzún, J. 1998. Geología, recursos minerales y riesgos ambientales conexos de la Región de
Coquimbo. In: La Región de Coquimbo. Espacios y Recursos para un Desarrollo Sustentable, 19 p.
Univ. de la Serena (available in electronic format)
- Oyarzun, R., Ortega, L., Sierra, J., Lunar, R. y Oyarzún, J. (1996) . The Manto-type gold deposits of
Andacollo (Chile) revisited: A model based on fluid inclusions and geologic evedence. Economic
Geology, 91: 1298 – 1309.
- Oyarzun, R., Ortega, L., Sierra, J., Lunar, R., Oyarzun, J. 1998. Cu, Mn, and Ag mineralization in the
Quebrada Marquesa Quadrangle, Chile: the Talcuna and Arqueros districts. Mineralium Deposita 33:
547-559.
- Oyarzún, J. (2000) Andean Metallogenesis: A synoptical review and interpretation. In: Cordani,
U.G., Milani, E.J., Thomaz Filho, A and Campos, D.A., Tectonic Evolution of South America, Rio de
Janeiro, pp 725 – 753.
- Oyarzún, J., Maturana, H., Paulo, A., and Pasieczna, A. 2003. Heavy metals in stream sediments
from the Coquimbo Region (Chile): effects of sustained mining and natural processes in a semi-arid
Andean basin. Mine Water Environ. 22: 155-161.
- Oyarzún, R. & Alvarez, P.A. (2001). Morfología de suelos de la Cuenca de Talhuén del secano
semiárido de la IV Región, Chile. Agricultura Técnica, 61(4), 517-521.
- Oyarzun, R., Oyarzún, J., Ménard, J.J., and Lillo, J. (2003) The Cretaceous iron belt of northern
Chile: role of oceanic plates, a superplume event, and a major shear zone. Mineralium Deposita, 38 :
640 – 646.
- Oyarzun, R., Oyarzún, J., Lillo J., Maturana H., Higueras P. 2007 Mineral deposits and Cu-Zn-As
dispersion-contamination in stream sediments from the semiarid Coquimbo Region, Chile.
Environmental Geology 53:283−294
- Oyarzun, R., Lillo, J., Oyarzún, J and Higueras, P. 2007. Plate interactions, evolving magmatic
styles, and inheritance of structural paths: Development of the gold-rich, Miocene El Indio epithermal
belt, Northern Chile. International Geology Review , 49, 9 : 844 – 853.
32
Technical Report on River Basin Characteristics, Pressures and Issues; Elqui River Basin, CHILE
- Oyarzun, R., Guevara, S., Oyarzún, J., Lillo, J., Maturana, H., Higueras, P. 2007. The Ascontaminated Elqui river basin: a long lasting perspective (1975-1995) covering the initiation and
development of Au-Cu-As mining in the high Andes of northern Chile. Environ. Geochem. Hlth, 28,
431-443.
- Paskoff, R. 1993. Geomorphology of Semiarid Chile (in Spanish). Ed. Universidad de La Serena,
Chile, 321 pp.
- Perez, C. 2005. Climatic change: Vunerability, adaptation and role of the institutions. Study of cases
in the Elqui Valley (in Spanish). Graduation Project, University of La Serena, 203 pp.
- Ruiz, C. (1965) Geología y yacimientos metalíferos de Chile. Instituto de Investigaciones
Geológicas, Santiago, 305 p .
- Salazar C (2003) Situación de los recursos hídricos en Chile. Reporte de Investigación. Third World
Centre for Water Management, the Nipon Foundation.
- Santibañez, F. 1985. Rasgos agroclimáticos generales de la zona árida de Chile. Sociedad Chilena de
la Ciencia del Suelo, 5: 1-28.
- Santibañez, F. 1997. Tendencias seculares de la precipitación en Chile. En Soto, G., y Ulloa, F.
(Eds). Diagnóstico de la desertificación en Chile. CONAF, La Serena.
- Souvignet, M. 2007. Climate change impacts on water availability in the semiarid Elqui valley,
Chile. MSc Thesis, Institute for Technology in the Tropics (ITT), Cologne University of Applied
Sciences. 110 p.
- Squeo, F.A., G. Arancio y J.R. Gutiérrez. 2001. Libro Rojo de la Flora de la Región de Coquimbo, y
de los Sitios Prioritarios para su Conservación. Ediciones Universidad de La Serena. 386 pp.
- Strauch, G., Oyarzún, J., Fiebig-Wittmaack, M., González, E., Weise, S. M. 2006. Contributions of
the different water sources to the Elqui river runoff (northern Chile) evaluated by H/O isotopes.
Isotopes in Environmental and Health Studies 42(3), 303-322.
- Vuille M, Milana JP (2007) High-latitude forcing of regional aridification along the subtropical west
coast of South America. Geophysical Research Letters 34, L23703, doi:10.1029/2007GL031899.
33