Tlie Hydrology-Geomorphology
Interface: Rainfall, Floods, Sedimentation,
Jerusalem Conference, May 1999). IAHS Publ. no. 2 6 1 , 2000.
Land Use (Proceedings of the
153
Response of a fluvial system to large-scale land use
changes: the Jablonka catchment, Slovakia
MIL OS STANKOVIANSKY, TOMÂS CEBECAUER,
JAN HANUSIN, MILAN LEHOTSKY, EUBOMIR SOLIN,
MARCEL SURI & JÂN URBÂNEK
Institute of Geography, Slovak Academy of Sciences, Stefânikova 49, 81473
Slovak Republic
e-mail: suri@,savba.sk
Bratislava,
Abstract We assess the geomorphic response of the Jablonka catchment
(163 km ), western Slovakia, to large-scale land use changes associated with
the collectivization of agriculture in the former Czechoslovakia in 1948. A
distinct acceleration of fluvial slope processes, as well as marked
strengthening of their geomorphic effect, followed collectivization and
disturbed the landscape quasi-equilibrium that existed at the end of the
nineteenth and first half of the twentieth centuries. Collectivization led to a
strong, well-defined pulse of disequilibrium that disrupted the balance of
catchment infiltration rates, runoff generation indices, sediment yield and
delivery ratio.
2
Key words fluvial slope processes; fluvial system; geomorphic response; land use change;
rural landscape; Slovakia; soil erosion
INTRODUCTION
The collectivization of agriculture in the former Czechoslovakia following political
and social changes in 1948 brought about a transformation in the spatial organization
of the rural, agricultural landscape. Historically stable land tenure was substituted by
vast collectivized land units. These changes, along with other activities, most of them
unfriendly to the environment, led to significant changes in the susceptibility of the
landscape to soil erosion and in the actual fluvial slope processes, as well as to the
marked geometric landform changes. To date, no attention has been paid to the
intensification of fluvial slope processes in Slovakia or the Czech Republic and their
possible linkage to collectivization. Only rough and considerably differing estimates
have been published. According to Bulicek et al. (1977), soil erosion has increased by
2-10 times (locally even 20-100 times), according to Jurân (1990) by 10 times and
according to Jambor (1997) by 4-5 times. These extreme estimates were widely
accepted and quoted in the Czechoslovak literature even though they were not
scientifically justified. Stehlik (1981) gives a qualified estimate of a 30% rise in soil
erosion efficiency in a selected area in the Czech Republic on the basis of assessing
plot adjustments using aerial photographs.
Barely any attention was paid to the pedological impact of the post-collectivization
period, as expressed by the changes in soil profile thickness, and even less to the
geomorphic effect, as expressed by the geometric relief changes. Karnis (1985), asserts
that in the years 1955-1985 in areas with severely eroded soils, a 3-8 cm, and in
places even 11-14 cm, thick cultivation layer was removed. Jambor & Zrubec (1994),
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Milos Stankoviansky
et al.
while reviewing the results of comprehensive research of agricultural soils, detected a
change of the original orthic luvisols to regosols, caused by erosion between 1961—
1991, in several localities near Kocin (the Trnava Hill Land). For Sâly & Midriak
(1995) this indicated the removal of a 10-20 cm thick cultivation layer. Mederly
(1992) used the same approach and found that near the village of Borsice, Czech
Republic, 50 cm of soil was removed from chosen convex topography, occasionally
more, while the accumulation in concave sections reached similar values. Lehotsky &
Stankoviansky (1992) and Lehotsky et al. (1993), using the Cs method in several
localities in a hilly relief area of western Slovakia (Home Smie, Euborca, Bzince pod
Javorinou), assessed the removal of an approximately 5 cm thick soil layer on the most
attacked slope portions and an approximately 10-20 cm thick accumulation in
depressed positions downslope. It should be noted that in addition to the fluvial slope
processes, the depletion of the soil profile or lowering of the terrain on the ridges and
slopes was also considerably influenced by tillage erosion, though this aspect was
totally neglected.
In this paper we use the Jablonka catchment to assess the geomorphic response to
changes in land use after collectivization
137
THE STUDY AREA
2
The Jablonka catchment (163 km ) is situated in western Slovakia, bordering the
Czech Republic, in the eastern part of the Myjava Hill Land and the adjacent parts of
the White and Little Caipathians. The maximum altitude (950 m) is in the White
Carpathians watershed in the massif of Vel'kâ Javorina Mt, and the lowest altitude
(180 m) is near the outlet of the Jablonka River from the Little Carpathians at
Cachtice. The characteristic feature of the topography of the Myjava Hill Land is its
plateau-like nature with a relief of the order of 40-120 m. It is composed primarily of
flysch-like rocks of medium to low resistance, resulting in a considerable thickness of
fine-textured regolith. Cambisols and luvisols are the main soil types on slopes, ridges
and plateaux. Mean annual precipitation is 650-800 mm. The catchment was almost
completely forested at the end of the thirteenth century. The lower and middle
catchment portions were covered by oak and oak-hornbeam forests, with the highest
portions by beech forests (Stankoviansky, 1996a).
APPROACH AND METHODS
To assess the response of the Jablonka catchment to the large-scale land use changes
following collectivization, we compared the land use pattern and dynamic aspects of
the landscape before collectivization (the beginning of the 1950s), to the present (the
1990s). The dynamic aspect involves the fluvial slope processes, namely the changes
of susceptibility of the area to soil erosion, changes in the behaviour and effect of
actual processes and the total geomorphic effect of processes during the entire postcollectivization period.
Changes in the land use pattern were identified by comparing land use maps
prepared using aerial photographs from 1955 and 1990 and GIS.
Response
of fluvial
system
to large-scale
land use changes:
the Jablonka
catchment,
Slovakia
155
Evaluation of the susceptibility of land use to soil erosion, before and after
collectivization, used rule-based modelling in a GIS environment. Susceptibility of
land use categories to soil erosion is expressed in words and by a susceptibility index
(ordinal numbers from 5 to -2). The susceptibility index is a qualitative judgement of
land use categories from the point of view of: (a) the susceptibility to the generation of
overland flow, (b) the protective function of vegetation against the erosional effect of
raindrops, and (c) the protective function of the root system against transportation of
soil particles. Areas with a negative index value are considered insignificant from the
viewpoint of susceptibility to soil erosion, regardless of positive index values of other
factors (relief and soil parameters).
To assess the susceptibility of land use to the generation of overland flow, we
assumed that the saturation overland flow prevails over infiltration excess overland
flow. The location of erosional forms (rills) was the reason underlying the above
assumption. Our field research confirmed the occurrence of erosion forms primarily in
concave-convergent parts of slopes that create favourable conditions for the origin of
saturation overland flow. If indeed infiltration excess overland flow dominates, the
erosion should be found also on the straight and convex-divergent slopes.
The fluvial slope processes and their particular geomorphological effect were
studied on the basis of detailed terrain documentation of erosion-accumulation
consequences of selected meteorological-hydrological events related to extreme
rainfalls or snowmelt. The data were compared to the testimony given by local fanners
concerning the course of processes prior to collectivization.
The geomorphic effect of fluvial slope processes occurring over the course of the
post-collectivization period was assessed especially for depressed landforms, filled by
young sediment. The rise of colluvial bodies at footslope positions or in the bottoms of
dells, dry valleys or incisions was measured by evaluating various buried objects and
buried soils, and using Cs and dendro-geomorphological methods.
137
RESULTS
Land use evolution before collectivization and its influence on fluvial slope
processes
The present-day cultural landscape of the study area is the result of a relatively short,
approximately seven century long, anthropological transformation of a forested
landscape. Major stages of anthropogenic intervention relate to the foundation of
medieval villages in the fourteenth century and to the so-called Kopanitse colonization
beginning in the sixteenth century and culminating at the end of the eighteenth and
early nineteenth centuries (Stankoviansky, 1997a).
Large-scale forest clearing and creation of fields in the climatic conditions of the
Little Ice Age resulted in an enormous acceleration of fluvial slope processes,
both areal (the sum of sheet wash, rill and interrill erosion) and linear (gullying).
Significant geomorphic effectiveness was typical for gully erosion, resulting in a dense
network of peimanent gullies in places reaching a density of 11 km km""
(Stankoviansky, 1998a).
156
Milos Stankoviansky
et al.
The end of the nineteenth century brought about the lessening of the fluvial slope
processes. This was the result of afforestation of gullies and richer diversity of the
cultural vegetation cover which formed a mosaic actively controlling erosion. The end
of the last stage of the Little Ice Age in the mid-nineteenth century (cf. Lamb, 1984)
has undoubtedly also played an important role in the lessening of the above processes
(Stankoviansky, 1997b). This situation lasted practically until the beginning of the
1950s. The Kopanitse landscape that developed contained a dense network of small,
narrow contour plots but also gradient plots, alternating with islands of villages,
hamlets, meadows, pastures and forests.
Interpretation of aerial photographs taken in 1955 (Fig. 1(a)) shows that land use at
that time consisted of forests (5277 ha, i.e. 32.4% of the total area of the catchment),
arable land (7916 ha, i.e. 48.7% out of which 5930 ha, i.e. 36.5% was contour
cultivated, and 1986 ha, i.e. 12.2% was profile cultivated, i.e. perpendicular to the
contours), grass-shrubby stands (2001 ha, i.e. 12.3%), and settlements (893 ha, i.e. 5.5%).
Character of collectivization in the Jablonka catchment
The collectivization, carried out in the study area between 1949 and 1975, principally
resulted in large-scale change in the utilization of agricultural areas. The merging of
small private plots into large cooperative fields and drastic terrain adjustments
(levelling of the step-like character of slopes in place of terraced plots), accompanied
by the destruction of a network of artificial linear landscape elements, were the most
significant consequences of collectivization. Significant terrain adjustments were
performed also in the framework of land reclamation in the second half of the 1970s
and even in the 1980s. Especially negative features of collective farming were the
introduction of crop rotation unsuited to hilly landscapes, as well as the utilization of
heavy machinery.
Land use following collectivization, as identified from aerial photographs from
1990 (Fig. 1(b)), consisted of forests (6779 ha, i.e. 41.2% of the total catchment area),
arable land (6952 ha, i.e. 42.8%, out of which 4586 ha, i.e. 28.2% was contour
cultivated and 2366 ha, i.e. 14.6% was cultivated in a direction perpendicular to the
contours), grass-shrubby stands (838 ha, i.e. 5.2%), and settlements (933 ha, i.e. 5.7%).
Between 1955 and 1990 the forest area increased by 12 km and the area of grassy
communities diminished by 12 km . From the point of view of the spatial distribution
of fluvial slope processes, the changes in arable land are, of course, the most important
ones. The total area of arable land declined by 10 km . This shrinkage was caused by a
transformation to forest communities (52%), orchards and fruit plantations (32%) and
grassland (14%). In spite of the decrease of the area of arable land as a whole, the area
of the arable land cultivated along the profile increased by about 4 km . The largest
share in the increase of profile cultivated arable land was in the category of contourtilled arable land.
Of great importance was a change in the structure of the spatial units on arable
land as identified by air photos. In the pre-collectivization period, these units represent
blocks of narrow, small private fields with a homogeneous method of cultivation,
bordered by field roads, furrows or other artificial linear landscape elements. The postcollectivization period is characterized by large cooperative spatial units. In the former
2
2
2
2
,
8 0 0 metres
F i g . 1 L a n d use p a t t e r n before (1955) and after ( 1 9 9 0 ) collectivization (selected part
of the Jablonka c a t c h m e n t ) .
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Milos Stankoviansky
et al.
period, 2898 units (mean size 2.7 ha) were identified, while the latter had 977 spatial
units (mean size 7.1 ha). Inner heterogeneity created by the alternation of strips of
different crops sown on private fields is typical of the units before collectivization,
whereas the post-collectivization units are homogeneous due to monocultures on
cooperative fields.
Geomorphic response of the Jablonka catchment to collectivization
Change in susceptibility to soil erosion Contour tillage and terracing both hinder
erosion, while arable land cultivated in the direction of the slope creates optimum
conditions for the concentration of surface runoff, increase in kinetic energy, and
hence more erosion. Strip-cropping together with anti-erosional furrows dug accross a
slope are also generally considered as effective soil conservation measures mainly in
the case of fields with contour tillage, and partially in the case of fields with up-anddown cultivation. Taking this into account, we assigned a moderate (index 3) or high
(index 4) degree of susceptibility to the spatial units on arable land tilled along
contours and slopes before collectivization, while for the post-collectivization period,
we assigned a high (index 4) or very high (index 5) degree of susceptibility to soil
erosion (Table 1). The category of terraces on arable land for both periods was
assigned a low (index 2) degree of susceptibility to soil erosion (Table 1).
The susceptibility of the Jablonka catchment to soil erosion is conditioned not only
by land use, but also by topography (aspect, slope, profile curvature, contour
curvature) and soil (stability of soil aggregates, texture and moisture) parameters. Solin
& Lehotsky (1996) evaluated these parameters in the study area. An overlay of the
maps of susceptibility of land use to soil erosion from 1955 or 1990, by the maps of
susceptibility of the joint effect of topographic and soil factors to soil erosion,
highlights the landscape susceptibility to soil erosion both in the pre- and postcollectivization periods. The total area and percentage of the separate categories of
degrees of susceptibility to soil erosion are presented in Table 2. A distinct change in
the rate of areas with moderate and high, or a very high degree of susceptibility to soil
erosion is evident. The area with a high, or very high degree of susceptibility to soil
erosion increased by 40% after collectivization.
Change in active fluvial slope processes A great deal of information obtained
directly from detailed field research, and also from interviews with local farmers, was
used in the assessment of the susceptibility of the area to erosion processes. The main
changes in the operation and effect of active fluvial slope processes were:
(a) Temporal and spatial variability in fluvial slope processes caused by land use and
type of cultivation. These also affect hillslope portions where they had previously
been absent (e.g. on previous meadows, now transformed to fields), but are absent
today on former fields transfonned to meadows and forests, for example.
(b) Enlargement of fields and the removal of artificial linear landscape elements
resulted in a marked increase of slope portions regularly affected by intense areal
erosion. However, the intensification of slope processes was not area-wide but
differed from site to site in relation to the previous type of cultivation. In the
earlier landscape linear erosion was predominant, while in the post-collectivization
Response
of fluvial
system
to large-scale
land use changes:
the Jablonka
catchment,
Slovakia
159
T a b l e 1 E v a l u a t i o n s c h e m e of susceptibility of land use categories to soil erosion.
Categories
Susceptibility to soil erosion:
1955
1990
degree
index
degree
index
not relevant
-2
n o t relevant
-2
Hamlets
not relevant
-2
not relevant
-2
Industrial and agricultural units
not relevant
-2
not relevant
-2
A r a b l e land:
contour cultivated
moderate
3
high
profile cultivated
high
4
very high
5
terraced
low
2
low
2
m e a d o w s o n limestones and dolomites
low
2
low
2
m e a d o w s o n other rocks
very low
1
very low
1
m e a d o w - s h r u b o n limestones and
dolomites
low
2
low
2
m e a d o w - s h r u b o n other rocks
very l o w
1
very low
shrub-forest
insignificant
-1
insignificant
-1
alluvial forest
insignificant
-1
insignificant
-1
forest
insignificant
-1
insignificant
-1
fruit tree plantations
-
-
moderate
fruit tree gardens
very l o w
hop-gardens
-
Villages
Vegetation:
1
1
4
1
3
very low
1
moderate
3
Cottages
very low
Railway embankments
not relevant
-2
not relevant
-2
Dams
not relevant
-2
not relevant
-2
very low
1
T a b l e 2 Susceptibility of the Jablonka c a t c h m e n t to soil erosion.
D e g r e e of susceptibility
Area (ha)
% of c a t c h m e n t area
% of threatened area
4
1 408
8.7
16.7
3
5 168
31.8
61.3
2
1 841
11.3
21.9
1
10
0.1
6 882
42.3
-
964
5.9
-
-1
-2
C a t c h m e n t area
16 273
T h r e a t e n e d area
8 427
0.1
5
140
0.9
2.0
4
3 931
24.1
56.2
3
1 862
11.4
26.6
2
1 053
6.5
15.0
1
12
0.1
-1
8 186
50.3
-
1 094
6.7
-
-2
C a t c h m e n t area
16 277
T h r e a t e n e d area
6 997
0.2
landscape, areal erosion prevails. In relation to the land use changes, the
geomoiphic effectiveness of the areal erosion also increased for both rill/interrill
erosion and sheet wash (cf. Stankoviansky, 1997c).
(c) Land use changes and use of heavy machinery on cooperative fields also resulted
in a change in linear erosion. Formerly both permanent and ephemeral gullies were
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et al.
formed but this changed to the creation of ephemeral gullies only. Out of two basic
types of ephemeral gullies, the broader and shallower ones prevailed during the
study period. They were created by concentrated flow erosion during high
intensity, low-frequency rainstorms falling on an initially dry seedbed in the spring
months (cf. Poesen & Govers, 1990). The maximum width of individual
ephemeral gullies of this type reached 5-6 m. The depth ranged from several cm to
25 cm in the case of removal of the whole cultivation layer. Incision stopped upon
reaching a resistant soil sublayer, i.e. a plough pan. The narrower and deeper
ephemeral gullies, usually the result of low-intensity high-frequency rainstorms
(cf. Poesen & Govers, 1990), occurred rarely. Their depth during the investigation
period reached 50 cm and for the entire post-collectivization period increased to
1 m. All ephemeral gullies were erased by the subsequent tillage operation
(Stankoviansky, 1997c).
With regard to fluvial slope processes, the conclusions from observations during
the study period are:
- heavy spring rainfalls were the most harmful events,
- the geomorphic effectiveness of heavy rainfalls was much higher than the
effectiveness of snow melts,
areal erosion predominated over linear erosion,
- the most damaging partial erosional phenomenon was concentration flow erosion,
- the most affected landscape features were the slope hollows, dells and dry valleys,
where both areal and linear erosion occur,
- most of the material washed down from straight hillslopes by areal erosion
remained on footslopes and on floodplain margins. Material eroded by linear
erosion, and carried by concentrated flow along the thalwegs of different linear
landscape depressions, is largely carried away to a valley of a higher order. After
reaching the valley, the carried material is deposited in the form of various
colluvial bodies and partially carried away by local streams (Stankoviansky,
1997a).
Geometric landform changes The geometric landform changes following
collectivization represent the total geomorphic effect of consecutive erosionaccumulation events within the last five decades. The differences between geometric
changes is discernible if they are the result of erosion or accumulation. Repeated sheet
wash leads to slope lowering. Not much attention was paid to this phenomenon,
however, as it is practically unnoticeable to the naked eye. Moreover, slope lowering is
not exclusively the result of fluvial slope processes as tillage erosion plays a large role.
Repeated linear erosion in the thalwegs of depressed land forms resulted in a
deepening of the existing washed furrows, or caused new ones (Stankoviansky, 1998b).
Washed furrows ("Spiilmulden" in German or "niecki zmywowe" in Polish, described
by Klimaszewski (1981, p.298)) are very common landforms in the study area.
Visually more conspicuous and more suited for study are the geometric relief
changes resulting from repeated accumulation of eroded material in depressed
positions. It is possible to distinguish two basic types of geometric changes: (a) an
increase of colluvial bodies under the slopes at valley bottom margins caused by
deposition of material coming from the side, and (b) the increase of the bottoms of
Response
of fluvial
system
to large-scale
land use changes:
the Jablonka
catchment,
Slovakia
161
dells, dry valleys and incisions in them by deposition of material coming mainly or
exclusively from upper valley reaches.
Growth of colluvial bodies below horizontally straight slopes at valley bottom margins
The locality of Paprad (Fig. 2) is at the contact zone of the horizontally straight left
slope portion and the adjacent part of the floodplain, of the flat-floored valley of the
Kostolnik Brook, in the area of the Starâ Turâ community. A marked, flat, gently
inclined colluvial body follows the contact of the slope and valley bottom, almost
reaching the channel of the brook situated asymmetrically just below the opposite
F i g . 2 Valley b o t t o m deposits in the locality of P a p r a d . (a) m a p of the locality,
(b) schematic cross-section of the valley b o t t o m w i t h the site of the soil profile,
(c) stratification of the soil profile (on the basis of the M u n s e l l Soil C o l o u r Charts,
texture properties and h u m u s content).
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valley slope. A large cooperative field, created by the merging of former small contour
plots in 1959-1960, runs continuously from the slope to the footslope colluvial body
and extends to a narrow strip of alluvial forest following the channel. A soil profile,
excavated in the colluvium at a point situated 15 m from the west valley slope and
approximately 90 m from the brook, revealed a 70 cm thick layer of young colluvium,
burying the topsoil at the surface of the former valley bottom. It is believed that the
bed of young colluvium, delivered from the slope by areal erosion, was deposited after
collectivization. The assumption is based on the documentation of the geomorphic
effect of a heavy rainfall in this locality on 6 May 1993, as well as on personal
communication with local fanners, by means of which it was possible to compare the
effectiveness of soil erosion processes before and after collectivization.
In a neighbouring valley near the hamlet of U Otiepkov, a somewhat different
situation was found. The colluvial body under the straight slope is in the shape of a
cone, and its maximum thickness (as measured by buried fence posts) reaches 52 cm.
In this case it is exclusively a post-collectivization accumulation as the cooperative
field in this case originated in 1959-1960 by ploughing of a former meadow. The
material was delivered from the slope by concentrated flow erosion, and most of it
corresponds with the same rainfall event as in the case of Paprad.
Rise of bottoms of linear depressed landforms The filling of bottoms of such
landforms and their consequent rise makes it possible to separate the case of dells and
dry valleys from the cuts into these landforms. The only studied example of the former
case is the Kostolné locality, representing a dry valley. The extensive cooperative field,
comprising the whole valley bottom and its left side, originated by merging the former
small private plots in 1952. Terrain adjustments were carried out as late as 1978. The
right valley side and the steep valley head are now covered by grassland. To evaluate
the thickness of the post-collectivization accumulation at the bottom of the valley,
Cs was used. As sediment contaminated by Cs extends from the ground surface to
30 cm here, and the maximum reach in the bottom position was 65 cm, the minimum
thickness of accumulation, as well as the minimum rise of the valley bottom, is about
35 cm. The material was supplied from the arable land on the left side and mostly from
upper valley reaches during the erosion-accumulation events.
Better conditions for measuring the thickness of post-collectivization sediment­
ation were those of the cuts incised along the dry valley bottoms. In the Luskovica
locality, near the village of Krajné (Fig. 3), upper reaches of the valley are now used as
one large cooperative field created by the merging of previous small contour fields in
1959-1960. The last marked terrain adjustment took place here in 1978. A buried
telephone pole, erected on the former bottom of the cut in 1961, indicates a i m thick
layer of sediment generated during the above post-collectivization heavy rainfall
events (Stankoviansky, 1996b). A profile excavated near the pole revealed nine
sediment layers, distinguished by thin sheets of decomposed organic matter (grass),
ranging in thickness from 3 to 19 cm. These sediment layers presumably correspond to
nine erosion-accumulation events in the period after 1961. The sediment, delivered
from the valley head, was deposited due to the barrier caused by the embankment of
the access road, which leads obliquely through the valley bottom.
Even thicker amounts of sediment were observed in the cut incised along the
bottom of a dry valley near the hamlet of Huckovci near the village of Kostolné. The
137
137
Response
of fluvial
system
to large-scale
land use changes:
the Jablonka
catchment,
Slovakia
163
cut was almost completely filled by young sediments. The original base of the cut,
dated 1926-1928, was identified at a depth of 233 cm in the profile, on the basis of flat
stones and broken pottery dated by a local resident. This layer of sediment could have
been deposited after 1945, i.e. following bush clearing in the upper valley reaches and
the founding of small private fields, but especially after 1959-1960 when these small
fields were transformed into a large cooperative unit.
CONCLUSIONS
Collectivization caused large-scale changes in the use of the original landscape, and
led to a distinct acceleration of fluvial slope processes. This included:
- an increase of areas with a high, or very high degree of susceptibility to erosion
processes by about 40% (in spite of the overall shrinkage of the arable land
area),
- a significant increase of slope portions regularly affected by intense areal erosion,
- an intensification of the geomorphic effect of linear (concentrated flow) erosion by
a distinct lowering of the density of linear landscape elements,
- an increase of the geomorphic effectiveness of the processes expressed by more
rapid filling of terrain hollows compared to the previous period.
These conclusions confirm that a marked intensification of the processes in the
post-collectivization period obtained in the Jablonka catchment, are also applicable to
other sub-mountainous agricultural landscape regions of Slovakia.
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Acknowledgements This research is part of the Slovak contribution to the joint
Israeli-Slovak-Czech project "Response of Fluvial Systems to Large Scale Land Use
Changes" (1992-1999) co-ordinated by Professor Asher P. Schick of The Hebrew
University of Jerusalem. This research was supported in part under Grant no.
HRN-5544-G-00-2060-00, Program in Science and Technology Cooperation, Office of
the Science Advisor, US Agency for International Development, and in part under
Grant no. 4063, Scientific Grant Agency of the Ministry of Education and the Slovak
Academy of Sciences (VEGA).
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