CHAPTER- I
Introduction
1.1 General: The Himalaya is youngest and northeast-southwest trending
mountain system in the world having about 2400 km length and width varying
from 230 to 320 km. It is located in the territories of India, China, Nepal and
Pakistan. It was formed as a result of the collision between Indian plates with
Eurasian plate. Himalaya is very much attractive to the earth scientist because
ar
of its complex geological setting geo-hydrology, geo-environment, mass
movement, erosion, landslide etc. The Himalayan orogenic belt is divided from
west to east into three distinct regions- the western, central and eastern
Himalaya. The western Himalaya cover the region from west of river Kali and
el
extends through Kumaun, Garhwal, Himachal Pradesh and Kashmir regions
(Thakur, 1981). From south to north the western Himalaya consist of Outer or
Sub-Himalaya, Lower or Lesser Himalaya, Himadri or Higher Himalaya,
Tethys Himalaya and Indus Suture Zone (Heim and Gansser 1939; Gansser
Es
t
1964; Valdiya 1980). The Lesser Himalaya is one of the most dynamic and
ecologically most fragile parts of the Himalaya. The Lesser Himalayan terrain
comprises a very thick succession of sedimentary and associated volcanic
rocks. It is surrounded by two thrusts i.e. the Main Central Thrust (MCT) in the
north and the Main Boundary Thrust (MBT) in the south. The Lesser
Himalayan terrain has a complex geological history and tectonic framework
(Gansser, 1964; Valdiya, 1980). It is the most stressed segments of the entire
Himalaya, not only the major thrusts such as MCT and MBT are active but also
few oblique and transverse faults are active. The structure of this zone is very
complex. These rocks are affected by a series of thrusts and faults due to which
the stratigraphic succession has been reversed in many places. The complex
lithological and tectonic setting of the terrain has given rise a unique type of
geomorphology. Landslides are a common phenomenon in this tectonically
active mountainous terrain (Gupta et al., 1993).
`
1
The geo-environmental status of the Lesser Himalaya is basically controlled by
geological factors evolved in consequence to the mountain building process
etc. The major thrusts and faults have caused the present fragile setup of the
Lesser Himalaya. The Lesser Himalayan Rivers are marked by steepened
gradients in the higher reaches, which gradually decrease in the frontal and
Bhabar region. Due to this setup several geo-environmental problems have
arisen in the region and the people are compelled to sustain under continuous
threat from the mass movement- landslides, erosion etc. The problems of this
ar
region are the mass movement, erosion and declining water resources. The
higher gradients of the river channels cause exceeding erosion of the terrain
and the ultimate effect can be seen in the low altitude.
The Dabka watershed is in the northwest of Nainital Hill. The watershed is
el
under geo-environmental problems i.e. mass movement, erosion, declining
water resource, hill slope instability, drying of the spring etc. These natural
hazards have caused damages to hill slopes, agricultural land, settlement
(Fig. 1.1) and road network. These problems are due to geological,
Es
t
gemorphological, hydrological conditions, increasing anthropogenic activities,
exploitation of natural resources, changing landuse pattern etc. Due to above
mentioned problems environmental degradation, climate change, socioeconomic imbalance, migration of people have been observed in the area.
Nature of terrain, rainfall condition, highly weathered formation, rugged
topography etc. have been combined to produce extensive landslide and
erosion in the area. Due to combined effect sediments are accumulation near its
outlet (Fig. 1.2). In the watershed the rainfall distribution is not uniform. In
areas where rainfall is high and rocks are highly weathered and extensive mass
movements have been observed. In areas where rainfall is limited slopes fail
by shallow erosion. Faults, fractures and joints are very pronounced in all
formations which play a very important role in mass movements. It is observed
that the area has closely spaced lineaments that are prone to mass movement
and severe erosion. Every year mass movement associated flash floods in the
area cause damage to road, infrastructure, settlement and agriculture and forest
land during the monsoon period.
`
2
ar
Es
t
el
Fig. 1.1: Due to creep on the slopes the school building has been extensively damaged.
Locality- Ghughukhan
Fig. 1.2: Large amount of sediment accumulation in the Dabka River near its outlet.
Location- Bagjala
`
3
1.2 Objective of the present investigation:-The detailed geological,
geomorphological, geohydrological studies were carried out in the study and
attempt has been made to establish the relationship between factors that
contribute to mass movements, erosion and decrease of water resources in the
area.
In order to investigate the cause of the problem the present study has been
taken up with the following objectives:-
instability.
ar
1. To understands the various geological features responsible for hill slope
2. To identify potential hazard zones causing severe mass movement and to
el
suggest measures to minimize/control the hazards.
3. To investigate geohydrology of the springs and to locate potential water
bearing zones.
4. To investigate the sediment load and rate of erosion at the pilot sites in the
Es
t
watershed.
5. To formulate strategy for harvesting rainwater in the head ward region of
the watershed.
6. To prepare hazard zone and various thematic maps using GIS and remote
sensing techniques.
The outcomes of this study would be helpful in various development activities,
water harvesting sites, recharge of springs and selecting site for creating spring
sanctuaries. The data generated would be useful to various line Departments for
adoption in their plans for sustainable development of the catchment. The
Uttarakhand Govt. has identified 1008 watershed in the state for detailed study
and strategy is being evolved to adopt watershed as development unit.
1.3 Previous work:-The rock formation of the Himalaya has been highly
disturbed by tectonic activities. Such activities have been represented by complex
folding, faulting and thrusting. A lot of geological work has done by different
`
4
organizations and institutions. Many assumptions are still doubtful and a large part
of the present area remains uninvestigated in depth. As early as 1851 Captain
Strachey introduced the Nainital area through geological sections from the
foothills to the Indo-Tibetan border. Thereafter, (Theobald, 1880; Oldham, 1880
and Middlemiss, 1890) defined the structure, geomorphology and lithological
succession of the adjoining area in detail. Holland (1897) assumed that the dykes
in the dolomitic rocks and slates (Krol) as members of a great intrusion. Auden
(1934) described the geology of the south-eastern Himachal Pradesh and then he
ar
extended his work in Garhwal and Kumaun and correlated these rocks with those
of Himachal Pradesh (Auden, 1937). Heim and Gansser (1939) has given the
geology of the Nainital Hills and established correlation between the limestone
and the shales of the Naina Peak, Deopatta and Ayarpatta with the Krols, and
el
between the multicolored clays and shales of Lariakantha and Bhawali with the
Nagthat Series. Gansser (1964) has given regional geology of Himalaya, which is
still considered as benchmark work for any study carried out in the Himalaya.
Es
t
Fuchs and Sinha (1974) have given the six-fold classification of the Krol
Formation, they assumed Krol-F as the additional and youngest unit. Valdiya,
(1985 and 1988) carried out landslide studies in Central Himalaya based on
geological and geomorphological parameters. Valdiya (1988) carried out
lithotectonic mapping of the area and provided the structural layout. Bartarya
(1988) studied erosion in a catchment of Gaula River in Kumaun Lesser Himalaya
and has considered geomophological and geo-hydrological approach for its
control. Tiwari (1995) carried out detailed sedimentological invstigation of BlainiKrol-Tal succession in the Titkhet area of the Dabka watershed and suggested
models for the depositional environment. The stromatolites of the Krols of the
Nainital area have been described by (Singh and Rai, 1977; Kumar, Arun 1980).
Sharma and Pant (2002) carried out study of landslides in the north western part of
Nainital hills, Kumaun Lesser Himalaya. Sharma and Pant (2002 a,b,c,d) have
carried out detailed investigation related to slope instability and hydrology of the
area A large number of geohydrological studies have been carried out in the
`
5
Himalaya that indicates the base flows of the streams and rivers is decreasing
steadily (Validya and Bartariya, 1989) and natural springs are depleting and
becoming seasonal (Bartariya, 1988; Valdiya and Bartariya, 1991). Inspite of the
above investigations the problem of mass movement and hydrological imbalance
in the region still persists.
1.4 Location and Approach: - The Dabka watershed is in the north-west parts
of Nainital (Fig. 1.3). The area lies between latitude 29024'26.59": 29030'17.01"
ar
N and longitude 79018'24.71": 79025'21.95" E and falls in the Survey of India
toposheets No. 53 O/6/SW, 53 O/7/NW and 53 O/7/NE in the scale 1:25,000. It
covers an area of about 65.88 km2. The watershed is bounded in the north by
NW-SE trending Kunjakharak ridge. In the south it is bounded by NE-SW
el
trending Ghughukhan-Hariyal-Titkhet ridge. The watershed is connected by 15
km long unmetalled road from Nainital side (Nainital- Kunjakharak road). It is
also approachable from Kotabagh in the foot hills. Many bridlepaths and
Es
t
footpaths are also located in the area.
`
6
ar
el
Es
t
Fig. 1.3: Location map of the Dabka watershed
`
7
1.5 Data collection: - Geological, hydrological and geomorphological data
have been collected through field surveys. The climatic data has been obtained
from meteorological stations established in the watershed under the research
Project “Geo-environmental appraisal of Dabka watershed, Kumaun Lesser
Himalaya, District Nainital” sponsored by the Department of Science and
Technology (DST), Government of India, New Delhi. The socio-economic data
related with population, occupational pattern, literacy, etc. were generated from
district levels.
ar
questionnaires method and various government offices at block, tahsil and
The other data has been taken from survey of India Toposheet (Scale 1:25,000),
forest maps, district statistical handbooks and National Informatics Centre
el
(NIC), Nainital, Rainfall data has also been taken from Indian Metrological
Department (IMD), Mukteshwar and from the recording stations established in
area. Soil map and other characteristics of the watershed were taken from soil
survey report of watershed carried out by National Bureau of Soil Survey and
Es
t
Land Use Planning (NBSS&LUP, 2004). Satellite data has been obtained from
FSI, Dehradun.
1.6 Methodology:-Survey of India Toposheet and satellite data have been used
for preparation of different thematic maps required for the study. For landslide
hazard zonation mapping the above mentioned satellite data has been used to
know the potential hazard zones causing severe mass movement by weightage
method and to understand the various geological features responsible for hill
slope instability. Land use/land cover change detection has been made by using
LISS III data of year 1998, 2002 (February month) and Google earth data of
2010. Morphometric analysis techniques have been used for the detailed
geomorphology of the watershed. Comprehensive field mapping has been done
using Global Positioning System (GPS), Altimeter and Brunton compass. The
detailed analysis of precipitation pattern and complete monitoring of spring and
stream flow was done to understand the geohydrological condition.
`
8
For soil erosion Universal Soil Loss Equation (USLE) has been used. The
geological, hydrological, geomorphological and climatic data collected from field
surveys and monitoring stations. Survey of India toposheet, satellite images were
used for creating different thematic maps in GIS environment using Remote
Sensing techniques e.g. drainage map, slope map, aspect map etc. Brunton
compass was used for taking the dip and strike of the exposed rock which was
required for the study. V-notches have been installed at different location in the
study area to monitor the erosion. Rain gauges, Pan evaporimeters, Hygrometer,
ar
Maximum and minimum Thermometer have been installed at three stations to
record the metrological condition of the watershed. For estimation of Gross soil
erosion, Universal Soil Loss Equation (USLE) was used. To formulate strategy for
harvesting rainwater in the headword region of the watershed, water harvesting
el
structure sites have been proposed.
1.7 Demography: - There are total 15 villages in the watershed (Fig. 1.4). The
settlements are found in the foot hill, southern parts, eastern parts and along the
Es
t
road from Ghughukhan to Binayak area. The population in the foot hill area is
higher than the uphill side of the watershed. The total population of the watershed
in 1991 and 2001 were 3526 and 5126 respectively. Saur village has highest
population in 1991 was 964 persons (27.33%) and in 2001 was 1367 persons
(26.66%) and in 1991 Dhanak has the lowest population 23 person 0.65% and in
2001 Baluti has lowest population 24 person 0.46% of the total population of the
watershed (from Census data 1991 and 2001). Population growth during 19912001 was 45.38%. The higher caste i.e. Brahmins and Rajput dominate which
constitute about 84% and population of lower cast is about 16%. Out of total
population only 48.30% are literates (Census data, 2001). It has been observed that
the male and female literacy ratio is 64 and 36 respectively. In the watershed
81.11% are cultivators, 3.28% agricultural workers, 4.91% household workers and
7.92% are occupied in non- agricultural practices.
`
9
ar
el
Es
t
Fig.1.4: Village map of the Dabka watershed
`
10
1.8 Soil type: - Broadly the texture of the soil of this watershed can be
classified as Fine loamy, Coarse loamy and Loamy skeletal (Fig 1.5). Depth of
soil varies from moderate shallow to moderate deep. Soil of the watershed can
be categorised under Hydrologic Soil Group B and C. Soil map and other
characteristics of the watershed were taken from soil survey report of
watershed carried out by National Bureau of Soil Survey and Land Use
Planning (NBSS&LUP, 2004). The NBSS&LUP has assigned Soil Mapping
Units (SMU) to different soil characteristics and the same is taken in this study
ar
for assigning values for different soil related parameters. Detailed information
Es
t
el
for different soil mapping units is given in (Table 5.3.2).
`
11
ar
el
Es
t
Fig.1.5: Soil map of the Dabka watershed
`
12
1.9 Climate: - The climate of the area is subtropical in nature being cold in
winter and warm in summer. In the northern part above 1990 m the watershed
also receives heavy to moderate snow fall in the winter season. The climatic
data is obtained from the metrological stations (Fig. 1.6 and 1.7) which have
been installed in the watershed under a project sponsored by Department of
Science and Technology (DST), Govt. of India, New Delhi. The average
annual humidity of the watershed is 72.14%. In summers the average humidity
of the watershed rise upto 75.81% in the forest area. In the down slope areas of
ar
Kunjakharak-Binayak it is about 85.16% and in lower height of Hariyal area it
is about 76.50% in summer. During the winter month the average humidity is
about 79.08%. The watershed receives average annual rainfall of about 172.8
cm. (Table 3.2). The watershed enjoys maximum rainfall in July, August and
el
September which is about 68% of the total annual rainfall. The minimum
rainfall occurs in February, March and November it is about 6% of the total
annual rainfall. In April, May and June months the watershed also receives
rainfall. The average annual temperature is 180 C. During summer the average
Es
t
temperature is about 240C, and it varies between 100 C in the mountainous
region and 380 C in southern parts of the watershed. In winters the average
temperature is about 110 C, it varies between 240 C and -20 C in the
mountainous region.
`
13
ar
Es
t
el
Fig. 1.6: Meteorological station established at Aniya
Fig. 1.7: Hydrological station established at Ghughukhan.
(Note the V- notches and sediment trap structure)
`
14
1.10 Vegetation: - The area consist different types vegetation cover. The main
vegetation of the study area are Pine (Pinus roxburghii),
Banj (Quercus
leuchotrichophora), Sal (Shorea robusta), Oak (Quercus incans), Toon
(Cedrela tonna), Burnas (Rhododendron) state tree of uttrakhand, Kafal
(Myrica sapida), Mehal (Pyrus pashia), Rianj (Quercus floribunda), Sagwaun
(Tectpma
grandis),
Suri
(Cupressus
torulosa),
Kharsu
(Quercus
semicarpifolia), Tiloj (Quercus foribunda), Kail (Pinus wallichiana), etc. At
common shrubs.
ar
some places Indofera Clerodendron, Rhododendron, Murraya etc. are the
1.11 Structural set-up of the area: - On regional basis, the area of
investigation is located between Ramgarh Thrust towards NE and MBT
el
towards SE (Fig.1.8). Towards the south-western part of the area the Lower
Siwalik abuts against the Krol Group along MBT (Karunakaran and Ranga
Rao, 1979). The rocks in the area have undergone polyphase deformation
which has led to complex structural setup (Tiwari, 1995). The area has suffered
Es
t
from three intense and feeble phases of deformation. The rocks exhibit diverse
degree and intensity of deformation which depends on the rheological
properties of available lithological units.
`
15
The F1 folds are well developed along Nainital-Kilberry road and in the
Badanthali ridge. The folds are isoclinal to open in nature. Such fold has
developed intense cleavage in rocks which is affected by subsequent episodes
of folding. The F1 folds are affected by second phase of deformation which has
lead to development of F2 folds. These are cylindrical type and most
conspicuous in the slates and marls of Krol Formation around Kilberry,
Kumukhet-Chhara section. The folds plung 10-350 towards WNW/W/SW or
ESE/E/NE. Out of the three phases the second phase of folding is highly
ar
intense which is dominantly responsible for all structural complexities as it has
given rise to over folded sequence in many cases. The entire area manifests
folds of diverse geometry such as parallel, cylindrical open, tight, isoclinal,
el
reclined, conjugate box, chevron and upright open wraps.
The third phase of the deformation has affected the F2 folds leading to
development of chevron, conjugate and box type folds. This episode is
represented by kinks and bends extensively developed in Infra krol (Kailakhan
Es
t
Member) and Lower Krol (Manora Member) slates (Tiwari, 1995). Their axial
planes exhibits steep dips and tend NE/NNE-SW/SSW direction. The axial
planes of these folders are more or less vertical. The angle between second and
third generation axial planes is about 850 in most of the cases. Apart from the
above structures, the area is manifested with local faults of different type i.e.
normal, reverse.
The major structures i.e. Ramgarh Thrust and MBT supported by phase wise
tectonic activities seems to have developed profuse jointing of the rock.
Bedding joints and veritcal joints are dominantly found in the sedimentary
proportion. The columnar joints are frequently formed in the quartzites,
rectangular joints are found mostly in dolomitic limestone.
`
16
1.12 Geological set-up: - The area under investigation forms part of the Krol
Group. It consists of diverse lithounits which range in age from Upper
Precambrian to late Protozoic (Valdiya, 1980). The generalized classification
of the sequence in order of superposition (Table 1.1) is based on the physical
characteristic and fauna of the lithological units. The geology of the area is
dominated by the presence of Jaunsar and Krol groups of rocks. The rocks of
the area have been correlated with their equivalent (Fig. 1.10), exposed in the
other part of the Lesser Himalaya. It seems that the (Table 1.1) geology of the
respectively.
ar
area is controlled by Ramgarh Thrust and MBT towards north and south
Table 1.1: Tectonostaratigraphic set-up of the Nainital Hills (Pant and
Goswami, 2003)
el
RAMGARH GROUP
------------------------------------ RamgarhThrust----------------------------------------
Es
t
Tal Formation
KROL GROUP
Krol Formation
Blaini Formation
------------------------------------------Sharp---------------------------------------------Nagthat Formation
JAUNSAR GROUP
Bhawali Quartzite
Bhimtal Volcanices
------------------------------MAIN BOUNDARY THRUST--------------------------SIWALIK GROUP
`
17
ar
el
Es
t
Fig.1.9: Geological map of the Dabka watershed
`
18
1.12.1 Nagthat Formation: - It comprises of assemblage of purple, fawn and
greyish quartzarenites with locally developed conglomerates and slates with
penecontemporaneous volcanics (Auden, 1934). The Formation in general, lies
over the Amritpur granite (1900±100 m.y.) exposed towards south of Bhimtal.
It is further sub classified into members viz. Bhimtal Volcanics and Bhawali
Quartzites. Bhimtal Vocanics are represented by basic volcanics. Their
volcanics comprise dominantly of basalt and tuffites. The basalt exhibits at
places amygdaloidal structure and largely comprises chlorite schists of spillitic
ar
nature (Diwaker, Rao et al., 1974) along with maroon purple slates. It is
followed by thick sequence which comprise of quartzarenite. These
quartzarenites belong to Bhawali Quartzite and are in intimate association with
penecotemporaneous Bhimtal volcanics in the area of investigation (Table 1.1).
el
The Bhawali quartzite comprises of pink, purple fine to coarse grained
quartzarenites and siltstone, shale and conglomerate horizon. Pant and Shukla,
(1998) recognized seven lithofacies and on the basic of its physical character
Es
t
concluded that Nagthat Formation’s sedimentation occurred in progradational
barrier island system. The Nagthat Formation exhibit a progressive upward
increase in grain size. A number of workers have assigned plaeozoic age to
Nagthat Formation (Auden, 1934; Raina and Dungrakoti, 1975; Valdiya,
1980). On the basis of regional geological setting and recent fossils in Krol
rocks Nagthat is considered to be as early upper Proterozoic age.
1.12.2 Blaini Formation: - It seeks its nomenclature from its type section
exposed along Baliana nala near Dhanaulti located on Mussoorie-Tehri road
(Valdiya, 1980). Blaini Formation comprises of polymictic conglomerates,
siltstones, quartzites, greywacke and grey olive green slates with lenticular
beds of purple to pink dolomitic limestone. The rocks are well exposed in the
north and north eastern part of the area under study (Fig. 1.9). Which extend
from Kilberry-
Ghughukhan-
Binayak-
Badanthali- Naunia
Binayak-
Kunjakharak and continuous further westward. The Blaini Formation is
completely developed in the mentioned extension and overlies the Nagthat with
sharp contact. On the basis of physical characteristic and lithological
`
19
characteristics of the Blaini Formation is sub classified into four members
(Table 1.2). Keeping in view the recent fossil founding from Infra krol and Tal,
the Blaini has been assigned late Precambrian (Azmi et al., 1981; Azmi, 1983;
Kumar 1984; Singh and Rai, 1977)
Table 1.2: Lithostratigrpahic set-up of the Titkhet Hills, Nainital
(Tiwari, 1995)
O
L
G
R
O
Es
t
U
Narain Nagar Member
Middle Tal)
Giwalikhet Member
(Lower Tal)
----------------------------------Transitional contact---------------------------Sherwood Member (Krol E)
Bisht College-Member
Krol Formation
(Locally developed)
Pashandevei Member (Krol D)
Barapatthar Member (Krol C)
Hanumangarhi Member (Krol B)
Manora Member (Krol A)
----------------------------------Transitional contact---------------------------Kailakhan Member (Infra Krol)
Pangot Member
Blaini Formation
Lariakantha Member
Bhumiadhar Member
----------------------------------Sharp contact----------------------------------Nagthat Formation
(exposed in the east and
north-east of the area)
ar
R
Tal Formation
el
K
P
JAUNSAR
GROUP
`
20
ar
el
Es
t
1.
`
21
12.3 Krol Formation: - It rests over the Blaini Formation with gradational
contact. The Krol Formation with dominance of calcareous sediments has been
further sub-classified into six members (Table 1.2). This sub-classification is
based on the diversity in lithology and mode of sedimentation (Valdhya, 1980).
On the basis of available ambiguous fauna, the Krol Formation has been
assigned ages from Precambrian to Cretaceous (Auden, 1934, 1937; Sitholey
et al., 1954; Ghosh and Srivastava, 1962; Singh and Rai, 1977). The recent
finding of Conodents by (Azmi and Pancholi, 1983) from the Phosphatic beds
ar
at the base of Krol D at Durmala in the Mussoorie Hill, places the Upper Krol
in the earliest Cambrian (Tommotion). The assemblage comprises of
Protohertizina ungulitforms, P. siciformes a Hyolithids such as Circotheca aff
el
obesa, bryozoans Eoscharophora etc.
1.12.4 Tal Formation: - The Tal Formation rests over the Upper Krol with
transitional contact which comprises a sequence of carbonaceous shales
interbeded with dolomite exhibiting cryptalgalmats and phosphatic nodules
Es
t
(Tiwari, 1995). This is followed by purple green slates interbeded with cross
bedded fine grained sandstone and siltstone. These rocks are known as Tal
Formation (Valdiya, 1980) have been further classified in two members (Table
1.2). The Tal Formation forms the core of syncline and dominantly comprise of
Giwalikhet Member in the area of investigation. The Formation is well exposed
to the west of Nainital around Narayannagar, Gairkhet, Timalpani and Titkhet.
The Giwalikhet Member comprises of siltstone, slates and has been correlated
with Chert phosphate and argillaceous member of Mussoorie hills. The
Narayannagar Member is co-relatable with aranecause sequences of Tal
Formation of Mussoorie syncline (Shankar, 1971; Bhargava, 1976; Kumar, et
al., 1993). Further, the summary of the regional correlation of the rock of area
is given in (Fig. 1.10).
The state of environmental condition is discussed in the following chapters.
`
22