Landform Analysis and Hydrological Responses of Dhundsir Gad (Alaknanda Basin) Summary

Transcription

1 Landform Analysis and Hydrological Responses of Dhundsir Gad (Alaknanda Basin) Summary Submitted for the Degree of Doctor of Philosophy in Geography by Hari Ballabh Under the Supervision of Devi Datt Chauniyal Professor Center Department of Geography H. N. B. Garhwal University, Srinagar, Uttarakhand

2 SUMMARY Landform Analysis and Hydrological Responses of Dhundsir Gad (Alaknanda Basin) Key word: Landforms, Socio economic factor, Geo-hydrology, hydrology, Sediment load and Denudation Introduction The drainage basin, or watershed, is the fundamental unit in geomorphology within which may be studied the relations between landforms and the processes that modify them. The study of basin morphometry attempts to relate basin and stream network geometries to the transmission of water and sediment through the basin. The size of a drainage basin influences the amount of water yield; the length, shape, and relief affect the rate at which water is discharged from the basin and the total yield of sediment; the length and character of the streams channels affect the availability of sediment for stream transport and the rate at which water and sediment are discharge The hydrological characteristics of a geographic entity, or catchment or watershed are mainly the reflections from the existing salient features of its landforms or geomorphology. Geomorphology is a branch of physical geography which lies between geography and geology. It is the science of landform development and its evolution. So that it is closely related to earth's surface geology, hydrology and meteorology. Various exogenetic and endogenetic processes account for the development of different types of landform features. Consequently, landforms are generally treated as a part of the physical environment of the human beings, but emphasis usually is placed upon man's adjustment to, and uses of landforms rather than upon landforms (Thornbury, 1954). Systematic description and analysis of landforms serve as the foundation of environs and earth sciences. Previous Literature Pre Detrict et al. (1982) have suggested basic rules for developing water sediment budget with examples from forested areas of the Pacific Northeast. Reid (1982) has examined problems and difficulties in modeling sediment supply through the hills and slope aspects. The problem of large woody debris in streams, which affects sediment storage in drainage basins, has been attempted by Siomens et al. (1982), Lehre (1982), Caine (1986), Dietrich et al. (1978), Haigh (1982), and Harvey (1982), etc. In the context of Uttarakhand Himalaya Rawat (1987) selected a pine watershed in Almora district of Uttarakhand for monitoring hydrological data (Haigh and Rawat, 1993). Out of this micro 2

3 watershed of different environmental conditions, these were instrumented in the Kumaun Himalaya (Valdiya and Bhartariya, 1989). Valdiya and Bhartariya (1989), Rawat and Rai (1993), Rawat and Geeta (1998), Rawat, Kaur and Geeta (2000), and Rawat (1997) also completed research projects based on water discharge and sediment budget in the forested and deforested watershed systems of the Central Himalaya in India. Chauniyal (2000) has also completed research projects on the comparative study of water discharge and sediment load budget in relation to integrated ecodevelopment. The Central Water Commission of Government of India is continuously monitoring a hydrological data of Indian Himalayan Rivers. The Central Water Commission does not cover the small streams (lower order) which occupy the maximum area of the mountain watersheds. Significance of the Problem There is a diversity in landforms on the earth's surface. These landforms are described after paying attention about the roles of geomorphic processes and historical events. This all makes one to understand the landforms development and the effect of geomorphic processes affected mainly by human beings. Watershed analysis provides a framework for ecosystem management which is currently one of the best options for conservation and management of natural resources. The water cycle regulates and reflects the natural variability of the physical processes which affects the ecosystems. Keeping in mind these facts, the present problem is determined for study. Selection of the Study Area The study aims at recognizing and classifying sedimentary nature of landforms in relation to other types of landforms. The small drainage basin which is relatively homogeneous in character, becomes possible to monitor the hydrological data and to obtain certain indices of the basin. The `Dhundsir Gad watershed consists of diversified morpho-units on account of different type of geological structures and drainage patterns. The watershed encompasses several geomorphologic features like small 'V' shaped valleys. Fluctuation of water discharge in different seasons and increasing amount of sediment load in streams are the widespread problems in the Himalaya. There have been multiple effects due to a number of biotic interferences in this sensitive part of the region. The causes of environmental problems are mainly human actions, agricultural extension, new road construction, deforestation and developmental activities which collectively have posed serious threats to the surrounding environment. There are scarcely any of the geographers and scientists who have ever properly surveyed the present selected watershed so far. Objective of the Study In a nutshell, the basic objectives of the study are as under: 3

4 (i) (ii) (iii) To carry out geological and geomorphologic investigations and their impacts on existing hydrological characteristics. To measure water discharge and sediment yields, and To unfold environmental factors influencing hydrological characteristics with special reference to soil erosion and to suggest their mitigating measures to minimize adverse impacts. Research Methodology The combination of qualitative and quantitative research techniques in studying landform evolution and hydrological analysis have been followed under the present context. The present study is therefore carried out in the following steps. (i) Topographical sheets : The study area falls within the Tehri district of the Garhwal region covered by Survey of India Topographical sheets No. 53 J/11, 12 and 15. The base maps of the study area were prepared on the scale 1/50,000. The basin geometry in this way was assessed by the morphometric analysis of `Dhundsir Gad. The morphometric attributes such as absolute relief, relative relief, drainage texture, drainage frequency and dissection index were assessed and analyzed at an interval of 20 meter contour after following Raise and Henery (1937). Slope angles and morphological mapping techniques were applied within the basin (King, 1971). (ii) Watershed instrumentation: The water gauge stations were constructed near the confluence of `Dhundsir Gad. The site being almost natural was selected for monitoring water discharge and velocity. The water velocity was measured by both `pigmy water current meter and `float method. (iii) Primary and secondary sources: In addition to experimental study of field monitoring, the primary data regarding natural and anthropogenic hazards especially on land use practices, deforestation, and soil erosion, etc. were collected from the field study. The secondary sources in the form of relevant information from District Statistical Office, Water supply, and the relevant reports and published literature were contacted as the secondary sources of information. (iv) Assessments of suspended and dissolved load: The suspended load after collection of water samples was analyzed and measured in the laboratory. In this process, water samples during the peak run off season were collected and a sample of water with 250 ml bottle was processed in the laboratory. The samples taken were filtered through a whats man filter paper. The collected 4

5 sediments from the collected water samples were dried with the filter paper and then was used for weight measurement of the sediment discharge. (v) The bed load assessment: The areas covered by alluvial fans nearby confluence were demarcated to obtain bed load. With the help of per unit area demarcation and the material deposited within a specified area of the alluvial fans, bed load was obtained by weight and volume. The first order of streams to estimate the bed load was applied under the present study context. (vi) Meteorological data: Meteorological data in geohydrological analysis are very important. Temperature and rainfall data were collected mainly from secondary sources. Temperature from High Altitude Plant Physiology Research Centre (HAPPRC) and rainfall data from the Kiratnagar tehsil were collected. (vii) Human impact assessment Anthropogenic activities in the form of land use, mining, construction of roads, settlement, canals and other technical work was analyzed by using a variety of field techniques. Socio-economic impact was assessed at village level by the Census data through a case study. Geographical Location `Dhundsir Gad falls between Pauri ridge (elevation over 2000 m asl) and Mayali ridge (the water divider of Rivers Bhilingana and Mandakini). The area is extended in a geographical area of about 50.5 km 2 and is located between ' to ' N latitudes and ' to ' E longitudes. The altitude of the basin ranges from 520 m to 2360 m. Administratively, the present study area comes within the jurisdiction of Tehri district of Uttarakhand state (Fig.-1). The study area comprises in the part of tehsil Kirtinagar of Tehri Garhwal. The `Dhundsir Gad is the fifth order tributary of River Alaknanda. Historically, this area comes in one of the holy places of Uttarakhand, namely, Dhundprayag. The altitudinal variation of the Dhundsir Gad is from 520m (confluence) and 2360m (Gaddikhal top). Geologically, the watershed area is divided into Garhwal group and Chandpur group of rocks. The North Almora Thrust (NAT) separate them from each other which passes 5

6 through the southern part of the study area from NW-SE direction. Garhwal Group of rocks consists of quartzite limestone and biotite gneisses. About 2/3 part of the basin is under quartzite rocks. A thick pile of fine to course grained grayish brown to gray quartzite is characterized by the presence of thin layers of the sercite. The rocks have suffered low grade metamorphism up to chloride grade. Generally, the metabasics rocks are associated with quartzite. The metabasics are predominally made up of chlorite and hornblende. Ferruginous quartzite is well exposed around the central part of the study area. Some thin patches of dolomitic limestone is also found in the upper part of the basin. It is well exposed along river sides on the valley slopes. South of the NAT Chandpur phyllite is well exposed. The schistose phyllite is exposed along the NAT. It shows well developed crenulation of strainslip cleavage. NAT is the main structural feature of the study area. Other structural features are faults and folds on quartzite rocks. Other minor structural features are lineaments. Lineaments are many lines on the maps and that are structurally controlled. There are three trends (NW-SE, NE-SW and N-S) of lineaments found in the study area. The evolution of the Dhundsir Gad is into fourth stages. The soil profile type near the springs and seepage zone, where the land is partially irrigated, fine to medium grained sub-matured soil is found. Other part of the study area mainly covered by skeletal and clay soil. The development of the basin seems to be a close relationship between the present day landforms and the structural and tectonic features i.e., folds, faults thrusts etc, The course of recent day drainage pattern also follows the trend of weak zones i.e. faults. The varying lithology of the rock formations and the litho tectonic boundary of the area also guide the course of drainage patterns. The present landscape is, however, the result of the continued processes of sculpturing, of chiseling by the agents of erosion. The drainage system has been well developed in the metamorphic terrain and therefore, it is highly dissected. These processes have also modified the magnitudes of the slope in the basin. The present landscapes are mainly the result of the recent processes of denudation. The entire basin is divided into five altitudinal zones from 520m to 2360m with uniform 400m interval. The maximum 33.6% area of the basin is under high group of m followed by m i.e. 26.9%. The minimum percentage of the area is under 800m (6.95%) and above 2000m ((9.7%). The overall relative relief of the basin is 2140m. while it is very from place to place accordingly to configuration. Thus the relative relief of the study area basin is computed in one km 2 grids than classified in five groups ranging from below 200m to 600m with class interval 100m. the 6

7 maximum 46.8% area of the basin is under the high relative group of m. The group of blow 200m have only 2.8% of area. The distribution of relative relief clearly shows that more than 400m relative relief is common in the basin. The distribution of relative relief is denoted by low, moderate high and very high. Slope is very important element of the geomorphic study in the mountains. On the basis of Raize and Henery s method the slope of the area is classified into five classes with 200m/km interval. These five categories of slope were further condensed into five broad categories i.e. moderately gentles( < 200m/km), moderate ( m), moderately steep ( m), steep ( m) and very steep (> 800m.). The slope analysis shows that the area comes under the moderately steep zone. The entire basin area is also marked slope angling. The slope angles are under moderately steep slope class i.e %. The second heights percentage (31.11%) of the angles is in the category of moderate slope. Only 3.70% of slope angles is in the class of gentle class and 4.44% under very steep slope class. Thus it can be concluded that the area is under moderate to moderately steep slope angling class zones. It is remarkably noted that the northern aspects are steeper than the southern aspects. It is not in the study area but also all over the Himalaya. The north western aspects are good for biodiversity. There is close relationship of slope aspects, landforms types and natural vegetation in the study area. This chapter deals with the morphometric evolution of drainage network and its characteristics in which running water and associated transported load become most effective. The Dhundsir Gad is the 5 th order master stream of the study area which is the right bank tributary of the Alaknanda River. The Alaknanda is the one of the parental stream of the holy river Ganga. All the drainage lines meet to Dhundsir Gad which is formed a Alaknanda system. It is a perennial spring fed river through out the course. During 17.5 km. length, Dhankur Gad, Ulari gad, Margaon Gad, Athani Gad, Taula Gad and Chauni Gad are joined in it from left and right banks which make a dendrite pattern. There are 279 first, 60 second order, 17 third order and 2 fourth order streams in the study area. Basically there is dendrite and sub-dendrite drainage pattern is predominant in the study area. Out of that parallel, trellis, faulted, radial and annular drainage pattern is also found along the thrusts, faults, scarps and ridges. Complex drainage pattern is also found near tectonically disturbed zone. Active tectonics in a basin plays an important role in controlling a fluvial system through the change in channel slope and pattern. The multi phases of deformation stage are developed the drainage anomalies in the study area. The main features of drainage anomalies are faulted course, 7

8 compressed meander, pinching system course, hogback course, change in confluence angle and change direction etc. Thus it can be can be concluded that - Mostly dendritic and sub-dendritic drainage pattern is found in the quartzite dominated terrain of the study area The fluvial terrain in the study area have responded and adjusted to slow and subtle active tectonic movements. These adjustments can be recognized using geomorphic data. All subsurface faults in the basin are presently active and have produced distinctive response manifested as fluvial anomalies. Typical responses to uplift included development of compressed meanders, convexity in longitudinal profile, pinching of stream, anti flow direction, stream piracy, and frequent channel avulsions. The area subjected to upliftment show sudden change in flow direction because of the change in local relief and increased over bank flooding. The channel geometry deals with the geodynamics and geomorphic manifestation of crustal deformation processes. The geometry of the basin area can be divided into linear and areal aspects of the basin. Among the linear aspects stream order, number, length, length ratio, bifurcation ratio, sinuosity index are the main parameter while areal aspect includes the drainage frequency, density and confluence density. Results shows that the total number of streams in the basin are 360 which having about km. length. Maximum percentage of area (64.4%) is in 4 th order stream and minimum is in 2 nd order stream i.e %. First order stream having an area of 51.60%. out of the total basin area. The maximum stream length is found in the first order stream i.e. 104 km. followed by second order and third order i.e. 27 km. and 7.5km. respectively. The length of fourth and fifth order is almost equal i.e. 9 km. each. The length ratio ranges from 0.97 to It is higher (6.81) in the third order and lowest (0.97) in second order. In the present study area the length ratio decrease in successive order but high in third order. There is no specific pattern of length ratio in the basin. Bifurcation ratio is highest 4.65 in between first and second order while lowest in 3 rd 4 th and 5 th order. It shows that it does not give the definite criterion between order and number. It varies according to lithology, climate and vegetation cover of the study area. The sinuosity index is also calculated in the linear aspect of the basin. Sinuosity means the measurement of deviations of drainage lines from their geometric pattern. The sinuosity index of the Dhundsir Gad is calculated 1.02 which shows that it flows almost in straight course. Three other main streams (Nagailagair Gad, Taula Gad and Dhankur Gad) sinuosity index is also indicated that all the tributary streams are also flowing in a straight course. Their index values is estimated from 8

9 1.05 to It shows that Dhundsir gad and it s all tributaries are in youthful stage of geomorphic development. Areal aspect of the basin are the important factors which effect the development of the drainage system of any area. It is also controlled by stratigraphy structure of rocks, climate and biotic factors. Drainage frequency, drainage density, confluence density and hypsometric curves are included in the areal aspect of the basin. Drainage frequency and drainage density are find out on 1 km 2 grid of 1/50,000 scale toposheet. The average drainage density of the Dhundsir Gad is calculated 7streams/km 2. The drainage frequency of the Dhundsir gad have been put in certain category of 3 streams interval. Thus the five categories have been termed as low, moderate, moderately high, high and very high. It shows that 55.3 % of the basin area is under at moderate drainage density i.e. 5-8 stream per km 2 followed by moderately high category of drainage frequency. Minimum percentage of drainage frequency area is under low (5.8%) and very high (11.8%) categories. It is noted that high and very high drainage frequency are found in the gneissic and quartzite terrain because both the terrains are highly jointed and fractured while low drainage frequency is found in the phyllitic terrain. Phyllitic terrains are very main weathered and erodival in which drainage lines are well defined. Only well defined drainage lines are marked on the map so that their numbers are limited in the phyllitic terrain. Similar pattern is also found in the drainage density. The drainage density classes are classified in to 5 groups range from 0.5 km/km 2 to 0.4 km/km 2. The maximum area (48.35%) of the basin is fall in moderate density class (2-3) while minimum area (5.45%) is found in class of very low followed by very high drainage density (9.37%). The low and high density classes cover 15.32% and 18.51%area of the basin respectively. The distribution pattern drainage density same as found in the drainage texture/frequency. The confluence of streams are also counted in each grid of one km 2. Confluence density is important factor for the analysis of hydrological study of the basin. Confluence density is directly related with drainage density, stream order and their numbers. Streams with higher confluence numbers rank higher in power hierarchy, whilst stream with few confluence ranked lower in the hierarchy of power. Thus entire study area divided into four confluence density classes. It shows that maximum area of the basin is under the class of 6-9 confluence density per km 2. which is denoted by high. The second highest percentage of area (15.78%) falls in medium confluence density. The minimum percentage of area is under the class of above 9 which is denoted by very high confluence drainage density. 9

10 Thus it can be concluded that the high density of confluences is found along the main stream lines in the valleys. The confluence point density can be employ to obtain the power of a stream to erode in the absence of discharge data. The analysis provides a measures to specify the relative ability and power of streams, especially of identical orders, other things being the same. The area with abnormally high first order stream do not cover maximum confluence density comparison to high order stream. Hypsometric curve shows the ratio between the height and surface are of earth surface. The percentage hypsometric curve is a ratio of relative height and relative relief area with respect to the total height and total area of a drainage basin which is play vital role in geometric analysis. The hypsometric integral has been calculated for Dhundsir Gad and its tributaries. The forms of hypsometric curves and the values of the hypsometric integrals has been taken together, to identify the stage of basin development. It is notable that 46.66% area of the Dhundsir Gad shows erosional while rest of 54.44% area is hypsometric integrals that indicates the early matured stage of geomorphic development which ranges 43 to 59% of hypsometric integrals. Geo-environmental factors play a vital role in the determination of water discharge and sediment load in the stream. The various landform studies were mapped with the help of Survey of India topographical sheets (No. 53J/11,12,15,16) and the satellite data from the Google Earth. The detailed geomorphic survey was carried out through the longitudinal and transverse field traverses. Mainly the area is divided in three morphogenetic units. (i) Gneissic Terrain (ii) Quartzite Terrain (iii) Phyllitic Terrain The gneissic terrain is generally gentle slope terrain. The hill and water divides are rounded gentle slope valley spurs, colluvial fans and valley fills. The gradient of the drainage line is higher in this unit. This is the headwater zone of the watersheds. There are a number of planner surfaces on the top of the ridge. The ridges are under forests. The planner surfaces are used for posturing. The valley spurs and valley floors are colluvial fans which are used for cultivation. Due to high gradient of the streams, the water discharge is higher but sedimentation flow is low in this zone. The sub rounded type topography is found in all over the area. Most of the parts of the middle valley come under the quartzite terrain. A small strip of limestone is also observed and marked on the map. Metabasic are also found from Dungrivaha to Phayalgaon exposed along the road cut section. Phayalgaon area is technically most disturbed zone. Here, North-South, North West-South East and North East-South West lineaments meet each other. The earlier linear features displaced by later face of formation and lineaments are followed by channel courses. Therefore, the valley becomes very wide in this part. Multi phases of deformation stages are reflected on the tectonic landforms, that is, knick points faults, river terraces, epigenic 10

11 gorge, rapids, drainage anomalies, etc. There are very small ingrown meanders which are developed in interlocking spurs. At Khark, there are two sets of river terraces. Near Shivalaya, the river also flows in a narrow valley on the limestone terrain. The limestone is also uneven dissected terrain. The phyllitic terrain is basically pervious, weathered and dissected by denudation processes. Being associated with thrust zone, the rocks are highly crushed and weathered. It is most adversely affected by mass wasting activities, that is, slumping, active landslide, slip failures, deep incision of streams, etc. Therefore, the valley becomes wide in the thrust zone. The water divides are narrow and conical in shape. Due to the deep incision of the river, it flows through a gorge of its down part in phyllitic terrain. Except the terrain classification the landforms are also classified for the better understanding of the nature of watershed. The landforms are basically classified into following types. Table- Landform features in the study area Types Sub-types 1. Geotectonic (i) Thrust (ii) Fault (iii) Lineament (iv) Lithology features 2. Topographical (I).Ridge (II) Hill top (iii) Saddle (Khal) (iv) Planner surface Feature (a)conical (a) Rounded (v) Water divides (vi) Escarpment (b)rounded (b) Conical (vii) Scree slope 3. Slope Features (i) Concave slope (ii) Convex slope (spur) (iii) Break of slope (iv) Free face slope 4. Fluvial Features I- Erosional (i) Gully erosion (ii) Spur knick (iii) Point (iv) Drainage line (v) Ridge (iii) Rapids (iv) V Shaped Valley (v) River terraces (vi) Interlocking spur (viii) Waterfalls (ix) River bank erosion (x) spring (i) Scree cone (ii) River terraces (iii) Talus cone, II- Depositional (iv) Valley fills (v) Colluvial cone (vi) Alluvial fan (i) Active land slide (ii) Talus cone (iii) Old landslide (iv) Slumping 5. Mass Wasting (v) Rock fall 6. Anthropogenic (i) Road cut hazards (ii) Grazing land (iii) Gully erosion Hazards Source: Primary Survey Rainfall data shows that three years annual average rainfall of the area was recorded cm. Out of which % rainfall was recorded during monsoon, 23.36% in summer and only 9.34 % in winter season. Climatically the study area comes under semi humid region. But there is great different in lower reaches and higher reaches. Where the upper reaches received good rainfall the lowered reaches are dry. 11

12 Landuse data shows that maximum 55.79% area of the study area basin is under forest land. Agricultural land occurs only 34.59% while the minimum (9.62%) area is under waste land. The crop field terraces are made across steep mountain slopes. These generally have an outward slope ( ) and are poorly managed. Except the valley around Dang and Phayalgaon, the remaining land is less productive, as these areas remain under steep slopes, and insufficient irrigation facility. In the lower altitudes or valley bottom, the river supports both Rabi (winter) and Kharif (summer) crops. Paddy and wheat are the principal staple food crops of the villagers. The forest cover constitutes an area of 28.2 km 2 (55.79 %) as compared to agricultural land km 2 (34.59 %). The wasteland constitutes an area of 4.83 km 2 (9.62 %) of the total areas. The other important land uses, here referred as grassland and grazing land, are confined mainly to the higher reaches along the north-eastern border of the region. The wasteland or eroded land found in the middle part of the region has an area of 4.83 km 2 (9.62%) of the total area. The wasteland is mainly covered by rugged surface which is equally distributed in the basin. Actual assessment of forest cover in this region of Dhundsir Gad is having different compositions, which is partly because of peculiar topography and partly because of socio-cultural factors. The economy of the local people is basically dependent upon the surrounding forests. People derive fuel wood, fodder, timber and minor forest products for their subsistence. Forests in this area are generally found between m on the northern slopes and shrubs are found only in lower elevations. The evergreen or semi evergreen areas are scattered in the form of patches in the southern parts of the study area. It is observed that the distribution of forest patches increases from east to west and similarly from south to north. It is also observed that the slopes, which receive maximum amount of rainfall, have more dense forest patches in the eastern parts than that of the remaining parts in the valley. However, in the colder areas of the upper valley, Chir pine is seldom found above 1800 m. Besides forming pure stands, the Chir pine also grows in association with Banj Oak (Quercus leucotrichophora), Rhododendrons (Rhododendron arboreum) and kaphal (Myrica esculenta). Subtropical scrub type of vegetation is generally found on the dry exposed aspects in the lower Chir pine forests. It is, however, absent in the northern aspects above 1500 m. Dense Banj oak (Q. leucotrichophora) forests are found between 1500 to 2100 m generally substituting the Pine forests on their upper limits. Moru oak (Q. himalayans) is normally associated with Q. leucotrichophora in the lower reaches and with Q. semicarpifolia in the higher reaches. 12

13 The forests are regularly being degraded due to over exploitation for commercial purposes. Oak, being the prominent in terms of timber species, is obviously more in demand. Besides, oak is considered helpful in recharging water springs and underground water. The social science can make significant contributions in understanding and improving the socio-economic conditions of the existing society at a watershed management levels. Altitude and slope, play a vital role in the distribution of the villages and the inhabited population. The population is distributed mainly along the river valleys. However, one may notice greater concentration of population between m altitudinal zones. The Dhundsir Gad watershed has a great diversity in its terrain, climatic conditions and resource bases. These variations have resulted in uneven distribution of population. There are 1302 households who live in 22 villages within the present watershed. Every household has its own permanent house and separate cattle shed. It shows that most of the villages are located in scattered form in the basin. Most of the settlements comprising with 66.51% of the total are found in the altitudinal zones of m. Second highest distribution of settlements is with % of the total in the altitudinal zone of m followed by m zone (14.06%). Looking at the composition of different livestock populations, the maximum numbers were cow and ox (65.07%) which were followed by goats and sheep (22.92%) and buffalo (7.33%) in the Dhundsir Gad watershed. There is a close relationship among altitudinal zones, distribution of populations and livestock populations. It is made clear that agriculture is the primary occupation of the mountain people while the animal husbandry stands next. So that agriculture and animal husbandry are closely related to each other. In the altitudinal zone of m, the distribution of population and livestock both are on higher side. The livestock density is 189 km -2 in this zone and the distribution of population is also increased proportionately. The infrastructural and social facilities are not sufficient in the Dhundsir Gad watershed. Once, there was single motorable road that was passing through the watershed from the confluence at Phayalgaon. This road currently is under construction that would bisect the watershed into low and middle hills. The civic facilities like market for transaction, bank for loans and credit services, and hospital for disease treatment are at Kirtinagar. The socio-economic conditions of the watershed show that these facilities are minimum with very few economic opportunities for establishing market linkages. The scarcely available local resources are collected by the villagers to meet their requirement from the watershed. The high pressure of human and livestock population and increasing demands on these locally available natural resources have caused their depletion fast. The 13

14 heavy pressure on forest resources, changing pattern of land use and crop system have increased the rates of high run-off and soil erosion in these village ecosystems. As a result, environmental degradation is taking place at a greater speed that needs especial care in coming future from management viewpoints Hydrological Responses A detailed geohydrological study of the Dhundsir Gad in lesser Himalaya has been carried out since Nov to Oct (Four years). The 5 th order stream covers 50.5 km 2 area with 17.5 km. length which produces different hydrological results. The important conclusions are as follows:- (i) The climatic data show that the study area comes under semi rainfall zone. Comparison of four years rainfall data indicate that the total amount of rainfall shows no specific trends in successive years. Rainfall brings the most important factor to effect the surface runoff. The duration and intensity of rainfall directly influenced the water discharged and sediment budget. Only a small portion of the rainfall infiltrates underground while the reaming flew as surface runoff. (ii) The intensity of storms, the amount of rainfall, duration of rainfall of the storm, and anthropogenic activities within watershed accelerated rate of erosion in the catchment. (iii) Annual average discharge of the stream is thousand m 3 or 1.44m 3 /s. Out of that 85.97% water discharge was estimated in the rainy season. The average rate of discharge was l/s. The over all rate of water discharge is estimated 0.03m 3 /s/km 2 /y. (iv) Out of the total annual sediment budget about 46% was estimate bed load, 38.40% suspended and only 15.61% dissolved sediment. About 99.66%? sediments are monitored in the rainy season. The over all rate of sediment flow is t/km 2 /y. The rate of dissolved sediment is very low i.e t/km 2 /y. (v) The denudation rates of the study area show that the catchments are chemically eroding at the rate of 0.22 mm/y while the mechanical erosion rate is 1.20 mm/y. The gross rate of erosion is 1.42 mm/y. (vi) Thus it can be concluded that thousand m 3 average water discharge under cm annual rainfall is generated tons of total sediment load during four years which degrade the Dhundsir Gad watershed at the rate of 1.61 mm/y. 14

15 Integrated Eco-Development Planning Recommendation:. Every watershed has different hydrological conditions, which require a specific management and planning. Therefore on the basis of findings of the present study, some salient recommendations are behind made for the watershed under the following points (i) For the solution of hydrological problem, an interdisciplinary research should be initiated under the expert supervision for long term and reliable hydrological data of the study area. (ii) The land degradation problems such as mass wasting, soil erosion, flood damage, siltation and desertification should be given due attention and all possible efforts must be made to combat them. In view of the dynamics of catchment eco-system, it is necessary to work out the extant of environmental hazard so as to measure the magnitude of the problem. Special attention should be given to the proper utilization of spring water, its diminishing discharge and planning to recharge the desiccated springs. (iii) The basic problem as identified in the Himalaya region the collection of data related to water discharge and sediment budget in the high gradient 5 th order streams. It requires appropriate innovative methods and techniques for measuring the bed and suspended load at the out let point of streams. (iv) In view of increasing environment problems, it is most important to undertake similar studies with regard to hydrological cycle in other parts of the lesser Himalaya basin under different land use conditions. (v) Land use planning requires detailed investigation. The general land, degree and aspects of slope, distance from settlement and productivity in the catchment under joint collaboration of villagers, revenue and forest departments. Land management is one of the basic problems of the watershed under study. Land use planning required detailed investigation. The general land use planning should be based on altitude variations, types of land, degree and aspect of slope, distance from settlement and productivity in the catchment under study. There are three important sectors of land namely (i) agricultural land (ii) waste land and (iii) forest land. There is a need for proper planning and practices to manage each of the land types according to the changing altitude of the people. (vi) watershed management has been identified as a key for the planning, management and utilization of natural resources available in the Himalayan region. Such management and Utilization of natural resources available in the Himalaya region. Such management planning provides sound base to watershed to increase the long-term productivity and to optimize social and economic development. Thus Integrated watershed management will furnish solution for mitigating the problems being faced by human population in the hills 15

16 with regard to water, food and energy including maintain the ecosystem and hydrological balance. Watershed management has become indispensable requirement for Himalayan region. (vii) It can be concluded that micro catchment having villages is the best unit of environment al planning in the Himalayan region. Dhundsir Gad watershed presents a uneven distribution of landforms, settlements, receiving of rainfall and water discharge generating capacity. It required a further systematic investigations. It should not be make successful without fulfilling the basic needs of the people (viii) Much is yet to be learned about the important catchments. It deserves concentrated research policy under watershed management programmed. Table-1 Silent Characteristics of the Dhundsir Gad Parameter Parameter 1. Location Political Latitude Longitude District-Tehri (Uttarakhand) ' to ' N 16. Drainage pattern 17. Stage of geomorphic cycle 18. Environmental system Dendritic Young Naturally open system Temperate 2. Area of the watershed ' to ' E 19. Climatic zone 3 3. Stream order 4. Absolute height 5. Base level height 6. Relative relief 50.5 km2 5 th 2360 m. 520 m. 21. Average valley width 22. Channel index 23. Valley index 24. Hydraulic sinuosity index Main stream length 1840 m. 25. Topographic sinuosity index 81% 8. Periphery length 9. Circularly index 10. Numbers of streams 11. Stream length ratio 12. Average gradient 13. Channel slope 14. Valley length 15. Air length 15. Average slope 17.5 km. 37 Km Km (102.3m/km) 106m/Km. 17 Km. 15 Km m/Km. (46%) 26. Sinuosity index 27. Hypsometric integral 28. Cultivated land 29. Forest land 30.Other land 31. Total population 32. Total Livestock % 34.59% 55.79% 11.62% (2001)

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