MORPHOMETRIC CHARACTERISATION OF GAGAR WATERSHED IN KUMAONREGIONOFUTT ARAKHAND FOR MANAGEMENT PLANNING: A GIS APPROACH

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1 gric. Sci. Digest., 34 (3) : , 2014 doi: / GRICUTUR RESERCH COMMUNICTION CENTRE MORPHOMETRIC CHRCTERISTION OF GGR WTERSHED IN KUMONREGIONOFUTT RKHND FOR MNGEMENT PNNING: GIS PPROCH Prajakta D. her* and H.C. Sharma 1 Department of Irrigation & Drainage Engineering, College of Technology, G.B. Pant University of griculture and Technology, Pantnagar, , India Received: ccepted: BSTRCT Soil and water are of crucial importance for mankind. Water scarcity is a burning problem for the hill agrarians. Viable sources of water like springs, which are plenty in hills, are drying up because of inadequate recharge of flow domain of springs and there is great disturbance in hydrologic cycle of hilly areas. Planning and management of available natural resources are essential for sustainable development in agriculture. Keeping this in view the present study was conducted to study the morphological characteristics. Morphometric characterization was accomplished through obtainment of linear, areal and relief aspects of the basin using GIS software Geomatica-9.1. It was observed that there was a decrease in stream frequency with increase in stream order. The drainage network showed that the terrain demonstrates dendratic pattern with coarse texture type. ower value of drainage density of the study area indicated coarse drainage pattern and humid climate of the study area. The morphometric analysis of the watershed showed that, stream frequency and total length of stream segments decreased with increase in stream order. The higher value of bifurcation ratio indicated strong structural control on the drainage pattern. This study will be useful in the prioritization of soil and water conservation works for the efficient watershed management planning. Key words: GIS, Morphometric characterization, Natural drainage system, Prioritization. INTRODUCTION The hills of Uttarakhand are important from ecological as well as economical point of view. Ecologically, these hills are major source of runoff and sediment in several river basins. Economically, these hills are important for production of off season vegetables, fruits, timber, and various forest products, and generation of hydro-electric power. The most striking fact about the hills is the pressure of peoples on land. There are 17.6 people per hectare of cultivable land which causes difficulty for hilly agrarians in raising enough food grains to meet even their subsistence needs. In hills water moves rapidly and is not easily managed. Thus, there is an acute problem of soil erosion, poor vegetative cover, loose and poorly managed soils, high intensity of rainfall. Soil and water are the most precious natural resources for agriculture. Due to lack of proper planning and skills, there are many areas which suffer for need of utilizable land and water resources Therefore, for their proper development, management and utilization it becomes important to know about the morphological characteristics of the watershed. Morphometric parameters such as linear, areal and relief aspects represent the geometric features of the watershed and play a vital role in planning and allocation of water resources. Srinivasa et al. (2004) studied morphometric parameters of Pennar river basin around Pavagada, Tumkur District, Karnataka. lso, a GIS and remote sensing techniques were applied for morphometric analysis in the Chaka sub-basin of Purulia district (West Bengal) by Nag (1998). Kar et al. (2009) analyzed morphometric parameters of Bahasuni watershed, Dhenkanal district, Orissa for the development of *Corresponding author s prajakta_aher@iitb.ac.in, 1 Centre of Studies in Resources Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, , India

2 164 GRICUTUR SCIENCE DIGEST- Research Journal water resources in the watershed. Javed et al. (2009) performed Morphometric analysis for prioritization of sub-watersheds over the Kanera watershed, Guna district of Madhya Pradesh. Somashekar et al. (2011) performed quantitative morphometric analysis over Hesaraghatta watershed in Bangalore by estimating their linear, aerial and relief aspects. Keeping the above in view, the present study was conducted to characterise the Gagar watershed for its morphological properties, so that on the basis of these characteri stics proper watershed management plan can be taken up by the Uttarakhand Government. MTERIS ND METHODS General description of the study area: The study area i.e. Gagar watershed consists the Research Station of Govind Ballabh Pant University of griculture and Technology, Pantnagar and nearby area, forming the watershed, which is located near Bhowali in Nainital district of Uttarankhand state in India as shown in Fig 1. The watershed, covering an area of ha is located between " FIG 1: Study rea ocation of Gagar Watershed E to " E longitude and " N to " N latitude. The elevation varied from 1413 to 2380 m above mean sea level (MS). Slope, drainage, shade cast etc. are the important elements of topography. There was a lot of variation in the topography of the study area. In conformity with the dramatic altitudinal and climatic differences, the region supported variety of forest ecosystems. Mixed forests predominated in the area. The land slope varied from 2 to 75%. The soils of the Gagar watershed varied from extremely acidic to medium acidic with high organic matter content. These soils were fairly deep and moderately permeable. Very strongly acidic to medium acidic soils were also found at higher elevations, where rainfall was high and strong enough to leach down the bases from the soil minerals under temperate climatic conditions. The climate of the region was humid temperate but variations existed which largely depend upon the altitude and geological differences. The most common factors which lead to the development of microclimate were altitude, aspect, slope, drainage condition, vegetation etc. The valleys were hot in summer and cold in winter. The minimum temperature of the area was found to be - 4 o C in the month of January and maximum temperature was 41 o C in the month of May. The average rainfall in the study area was found to be 1040 mm, of which 70 to 80 per cent was received between June to September. With further increase in elevation, rainfall tended to decrease. Directional aspect played very important role in the development of vegetation, particularly at higher altitudes. Southern aspect was exposed to more insolation. The insolation on southern aspect was about 1.5 to 2.4 times higher than that of northern aspect. East and west aspects though received an equal amount of insolation; eastern aspect received the highest insolation during morning, before the air temperature becomes fully warm. Western aspects were comparatively hotter and drier than eastern aspects. The difference in the temperature on different aspects of the hills was the result of difference in insolation. The southern aspect was warmest and northern aspect was the coolest. spect plays an important role in receiving the rainfall and snowfall. Soil formation is also effected by it.

3 GIS application: Toposheet (No. 53 O/11) of Survey of India (SOI), of the scale 1: 50,000 of the study area, was used for the analysis of slope-area classification and watershed delineation. The study area was scanned (tiff format), translated to the pix format (PCIDSK format) using utility option of the software, and geo-referenced using Ortho Engine module of Geomatica (GIS and Image analysis software). This geo-referenced map was utilized to delineate the boundary of the watershed with GIS environment. The following local information was used as an input data in the geo-referencing of the toposheet. Projection UTM Earth Model: Ellipsoid or Sphere Zone 44 (78 o E to 84 o E) Rows R (24 o N to 32 o N) Datum D076 Indian [India, Nepal] Resampling method Nearest Natural drainage system: Drainage information was derived from SOI toposheet. The drainage pattern present in SOI topographic sheet was digitized. The streams of the area were seasonal in nature and remain dry in non-rainy seasons. Small amount of water was available only in the downstream portion of the main stream. This map is useful for site location for harvesting of surface water and site selection for harvesting structures and prioritizing the watershed development. The final drainage network map generated through overlay of digitized drainage pattern is shown in Fig. 1. Watershed boundaries were drawn based on water divide, derived from analysis of digital elevation model and morphology of terrain observed on the topographic maps and by physical check up in the area. M orphometric analysis of watershed: Morphologi cal charact eri zati o n represents geometry as well as geography of the watershed. Geometry of drainage basin and its stream channel system requi res the following measurements: (i). linear aspect of drainage network, (ii). areal aspect of drainage basin, and (ii i). relief aspect of channel network and contributing ground slopes. This analysis for the study area was accompli shed through the obtainment of linear, aerial and relief aspects of the basin and slope contributions. Vol. 34, No. 3, Ordering of streams:the quantitative study of channel networks used to begin with Horton s (1945) method of ordering of channels. Strahler (1957) proposed a modification of Horton s ordering scheme. Due to simplicity and greater freedom from subjective decisions, Strahler s method was preferred. inear aspects: In linear aspects, the parameters representing length were considered. i. Number of streams of given order (N u ) : The quantity N u represents total number of all streams, counted as the stream segments, having the order u present in the watershed. ii. Bifurcation ratio (R b ) : It was obtained by determining the slope of the fitted regression of the plot of the logarithm of number of streams on ordinate versus order on abscissa. The value of R b varied normally in between 3 to 5 and was a useful index for hydrograph shape for watersheds similar in other respect. The R b was computed using Horton s law of stream numbers which stated, The number of stream segments of each order form an inverse geometric sequence with order number or (1) R b N N u u 1 Where N u = number of segments of order u iii. ength of main channel ( m ) : This is the length along the longest water course from the outflow point of designated sub basin to the upper limit of the catchment boundary. iv. Mean stream length ( sm ) : It is the total length of all streams of order u in a given drainage basin divided by number of streams of order u. N u (2) i i sm 1 Nu v. Stream length ratio (R ) : This was estimated as the ratio of mean stream length of order u to the mean stream segment length of order (u-1). u R (3) u1

4 166 GRICUTUR SCIENCE DIGEST- Research Journal vi. ength of overland flow ( g ) : It is defined as the length of flow of water over the ground before it becomes concentrated in defined stream channels. Horton recommended using half the reciprocal of drainage density D for the average length of overland flow g for entire watershed. 1 g (4) 2D vii. Basin length ( b ) : Basin length is considered as the distance between outlet and farthest point on the basin boundary. viii. Basin perimeter (P) : Basin perimeter is taken as the length of watershed divide which surrounds the basin. ix. Fineness ratio (R fn ) : The fineness ratio is considered as the ratio of channel length to the length of the basin perimeter. real aspects: In areal aspects different morphologic parameters were considered which represent the area. Some of them are given below: i. Drainage area () : Drainage area is represented by the area enclosed within the boundary of the watershed divide. It is the most important characteristic for hydrologic design. ii. Drainage density (D) : It is estimated as the ratio of total length of channels of all orders in the basin to the drainage area of the basin. w Ni ij i j D 1 1 (5) iii. Constant of channel maintenance (C) : It was calculated as the ratio between the area of the drainage basin and total lengths of all the channels expressed as square meter per meter. It was also equal to reciprocal of drainage density. C 1 (6) D iv. Stream frequency (F s ) : It is known as the number of streams per unit area. Melton (1958) analyzed in detail the relationship between drainage density and stream frequency and gave following relation, 2 Fs 0.694D (7) N F s (8) The stream frequency was calculated by using equations 7 and 8. v. Circulatory ratio (R c ) : Basin circulatory ratio is estimated as the ratio of the basin area () to the area of a circle ( c ) having circumference equal to the perimeter of the basin. s basin shape approaches to a circle, the circulatory ratio approaches to unity. RC (9) C vi. Elongation ratio (R e ) : It is defined as the ratio between the diameter of a circle with the same area as the basin and basin length. The value of R e approaches to 1 as the shape of the basin approaches to a circle and it varies from 0.6 to 1.0 over a wide variety of climatic and geologic regimes. Typical values are close to 1 for areas of very low relief and are between 0.6 to 0.9 for regions of strong relief and steep ground slope. The elongation ratio was estimated by using equation 11. R e 2v d b (10) c Re...(11) bm vii. Form factor (R f ) : The form factor was calculated as the ratio of basin area () to the square of basin length ( b ) as defined by Horton. (12) R f 2 b viii.unity shape factor (R u ) : It was estimated as ratio of the basin length, b to the square root of the basin area. b Ru (13) w ix. Watershed shape factor (W s ) : The watershed shape factor was estimated as the ratio of main stream length, m to the diameter, D c of a circle having the same area as that of watershed. (14) m Ws D C

5 x. Drainage texture ratio (R t ) :Drainagetextureratio (R t ) was estimated as the ratio of total number of stream segments (N u ) of all orders to the perimeter (P) of that area. This definition of drainage texture ratio was given by Horton (1945). He recognized infiltration capacity as the single important factor which influences the drainage texture. N u Rt...(15) P Basin relief aspects: In basin relief aspects, the parameters evaluated are given below: i. Total relief (H) : The basin relief or total relief is the maximum vertical distance between the lowest (outlet) and the highest (divide) points in the watershed. Schumn (1956) measured it along the longest dimension of the basin parallel to the principle drainage line, and Strahler (1957) obtained it by determining the mean height of the entire watershed divide above the outlet. Relief is an indicative of the potential energy of a given watershed above a specified datum available to move water and sediment down slope ii. Relief ratio (R h ) : It is estimated as the ratio between the relief and the distance over which the relief was measured. It measures the overall steepness of the watershed and can be related to its hydrologic characteristics. iii. Relative relief (R p ) : The relative relief was estimated as the ratio of basin relief (H) to the length of the perimeter (P) as defined by Melton (1958). It is an indicator of general steepness of the basin from summit to mouth. H R p (16) P iv. Ruggedness number (R n ) : Melton (1958) and Strahler (1957) defined a dimensionless number called ruggedness number (R n ) as a product of relief (H) and drainage density (D) in the same unit. It combined slope and length characteristics in one expression. The areas of low relief but high drainage density were as ruggedly textured as areas of higher relief having less dissection. The ruggedness number was estimated using the following formula. R n H D Vol. 34, No. 3, 2014 (17) Parameters TBE 1: Statistics of drainage network Natural drains 167 RESUTS ND DISCUSSION The present study was conducted for land and water resources management and planning in Gagar watershed in district Nainital of Uttarakhand, using GIS. For this purpose, different thematic maps viz. contour map, aspect map, slope map, drainage map, village map, etc. were prepared using GIS software Geomatica v 9.1. Morphometric characterization was done through the measurement of linear, areal and relief aspects of the basin by using drainage map of the study area, which was prepared using Survey of India toposheet of scale 1: 50,000 with GIS environment. The planning, management and monitoring of the natural resources depend on the availability of accurate information regarding drainage network, slope, aspect, land use etc. Base maps were prepared using Survey of India (SOI) toposheet No. 53 O/11 of 1: 50,000 scale using GIS software Geomatica v 9.1. Drainage network and watershed boundary were extracted from the topographic sheet using Focus module of GIS environment with UTM projection. Drainage map: Vector layer of drainage network was digitized using topological line option of the software. Drainage map of the study area is shown in the index map itself and its statistics is given in Table 1. Number of I, II and III order streams was 16, 4 and 1, respectively. The length of smallest drain of I order was m whereas, longest drain was found to be m. The mean length of I, II and III order streams was m, m and m, respectively. inear aspects: The linear aspects of the channel system are stream order (U), stream length ( u ), stream length ratio (R l ), bifurcation ratio (R b ), basin length () and perimeter (P) and length of the overland flow ( g ). Stream order (U): Classification of stream order is important to index the size and scale of the basin. ccording to Strahler s system of stream ordering, the drainage of the watershed has I order II order III order Count Min. length (m) Max. length (m) Total length (m) Std. deviation (%) Mean ength (m)

6 168 GRICUTUR SCIENCE DIGEST- Research Journal TBE 2 - : inear aspects of Gagar watershed. Stream Number of Stream length, Mean stream Stream length Bifurcation ratio, R b order streams, N u u (km) length, sm (km) ratio, R II / I III / II I/II II/III I II III been classified and the main stream is found to be of 3 rd order stream. The maximum frequency in case of first order streams was 16 and that for second and third order streams was found to be 4 and 1, respectively (Table 2 - a). This stream order is used in calculation of some characteristics of the watershed. Stream length ( u ) : The total length of stream segments of first, second, and third order stream was found to be km, 3.41 km and 2.09 km, respectively (Table 2 - a). Table 2 - a also depicts that the total length of stream segments was maximum in first order streams and decreased with the increase in stream order. The variation indicates that the flow of streams was from high altitude with lithological variations and moderately steep slopes (Singh and Singh, 1997). This was satisfying Horton s general statement The number of stream segments of each order forms an inverse geometric sequence with order number. The mean stream length for the watershed was found to be 0.69, 0.85, and 2.09 km for first, second and third order streams, respectively (Table 2 - a). Stream length ratio (R l ): The stream length ratio showed an increasing trend in the length ratio from lower order to higher order indicating their mature geomorphic stage, whereas in the main watershed there was a change from one order to another order, indicating the late youth stage of geomorphic development of streams in the inter basin area. R l ranged from 0.31 to 0.61(Table 2 - a). TBE 2 - B: inear aspects of Gagar watershed. Mean bifurcation Basin length, Basin perimeter, ength of overland Fineness ratio, R fn ength of main ratio, R bm b (km) P (km) flow, g (km) channel, m (km) TBE 3 - : real aspects of Gagar watershed. Bifurcation ratio (R b ) : The bifurcation ratio of Gagar watershed was found to be 4 as shown in Table 2 - b. It indicates the homogeneous characters and geologic structure. The bifurcation ratio between first and second order stream indicates the nature of head ward erosion. Basin length () and perimeter (P): The basin length and perimeter of the Gagar watershed was found to be km and km, respectively (Table 2 b). ength of the overland flow ( g ) : Horton (1945) defined length of overland flow as the length, projected to the horizontal, of non channel flow from a point on the drainage divide to a point on the adjacent stream channel. g ength of over land flow is inversely proportional to runoff pattern, shorter the g quicker will be the runoff process and vice-versa. g of the watershed was found to be 0.18 km which indicates the later runoff process (Table 2 b). Table 2 b shown that the fineness ratio and ength of main channel of the Gagar watershed were found to be 0.35 and 4.20 km, respectively. real aspects: The areal aspects of the channel system are given as below: Drainage density (D d ) : Drainage density for Gagar watershed was 2.74 km/km 2, it indicates towards coarse drainage pattern and humid climate of the study area (Table 3 a). The coarse texture gives more time for overland flow and hence to groundwater recharge. In general, it has been Drainage/ basin Drainage density, Constant of channel C Stream frequency, F s Circulatory ratio, R c area, (km 2 ) D (km/km 2 ) maintenance,

7 observed over a wide range of geologic and climatic types, that low drainage density is more likely to occur in regions of highly permeable subsoil material under dense vegetative cover, and where relief is low. In contrast, high D d is favored in regions of weak or impermeable sub-surface materials, sparse vegetation and mountainous relief. Constant of channel maintenance (C) : It was found to be 0.37 km 2 /km which is the reciprocal of drainage density. It indicates the magnitude of surface area of watershed needed to sustain unit length of stream segment (Table 3 a). Stream frequency (F s ) : The stream frequency of the whole watershed was for orders III to I. Table 3 a shows that F s exhibits positive correlation with the drainage density value of the watershed, indicating the increase in the stream population with respect to increase in drainage density. Circularity ratio (R c ): It is influenced by the length and frequency of streams, geological structures, land use/ land cover, climate, relief and slope of the watershed. In the present study Table 3 a depicts that the R c value was 0.61 for Gagar watershed. Elongation ratio (R e ): The value of elongation ratio for Gagar watershed was 0.72, it confirms that the study area was having high relief and steep ground slope. The value of elongation ratio varies from 0.6 to 1.0 over a wide variety of climatic and geologic regimes. The elongation ratio varied from , which indicates high relief and steep ground slope (Table 3 b). Form factor (F f ): Value of form factor for Gagar watershed was 0.41(Table 3 b). It shows that the watershed was more or less elongated. The elongated watershed with low value of F f indicates that the basin will have a flatter peak flow for longer duration. Flood flows of such elongated basins are easier to manage than from the circular basin. Unity shape factor and watershed shape factor of the watershed were calculated as 2.57 and Vol. 34, No. 3, 2014 TBE 3 - B: real aspects of Gagar watershed. Elongation ratio, R e Form factor, R f Unity shape factor, R u Watershed shape factor, W s Drainage texture ratio, R t TBE 4: Relief aspects of Gagar watershed Total relief, H (m) Relief ratio, R h Relative relief, R p Ruggedness number, R n , respectively and indicates elongated shape of the watershed. Drainage texture (T): For Gagar watershed, it is one of the important concepts of geomorphology which means the relative spacing of drainage lines. Drainage lines were numerous over impermeable areas than permeable. The value of drainage texture T was found to be In the present study, the drainage density (Table 3 b) is of coarse drainage texture, coarse drainage pattern and humid climate of the study area. The coarse texture gives more time for overland flow and hence to groundwater recharge. ow drainage density generally results in the areas of highly permeable subsoil material and dense vegetation (Nag, 1998). Measures Involving Heights: Relief is the elevation difference between the highest and lowest points on the valley floor of a watershed is known as the total relief of that watershed. The relief of the Gagar watershed was 967 m (Table 4). Relief ratio (R h ): ccording to Schumm (1956), there is direct relationship between the relief and channel gradient. There is also a correlation between hydrological characteristics and the relief ratio of a drainage basin. The R h normally increases with decreasing drainage area and size of sub-watersheds of a given drainage basin (Gottschalk, 1964). It measures overall steepness of the watershed and is also considered as an indicator for the intensity of erosion process occurring in the watershed. High value of relief ratio is the characteristics of the hilly region. Table 4 shows that the value of relief ratio R h for the Gagar watershed was Ruggedness number: The areas of low relief but high drainage density are as ruggedly textured as areas of higher relief having less density. For the Gagar watershed, it was found to be km (Table 4). This number represents that if drainage density increases, keeping relief as constant, then average horizontal distance from drainage divide to the adjacent channel is reduced. On the other hand

8 170 GRICUTUR SCIENCE DIGEST- Research Journal if relief increases, by keeping drainage density as constant, the elevation difference between the drainage divide and adjacent channel will increase. Such studies may be useful in the prioritization of soil and water conservation works for the efficient watershed management planning. Prioritization on the basis of morphometric parameters: For prioritization work the watershed is divided in to mini or micro watersheds. The parameters such as bifurcation ratio, drainage density, texture ratio, stream frequency, circulatory ratio, form factor, compactness ratio, and elongation ratio are used for the prioritization of mini watersheds for conservation measures. Previous studies have shown that shape parameters show negative correlation with runoff as well as soil erosion, while the other parameters show positive correlation with soil erosion (Thakkar and Dhiman, 2007). For first four parameters (bifurcation ratio, drainage density, texture ratio and stream frequency), rating is done by assigning highest priority i.e. 1 for the mini watershed having maximum value of the parameter, priority 2 for the next higher value and so on. The mini watershed which got the lowest value is assigned the last priority number. Remaining four parameters (circulatory ratio, form factor, compactness ratio and elongation ratio) rating is done by assigning highest priority 1 for the mini watershed having minimum value of the parameter, and similar procedure is followed till the last priority number. The compound parameter values of mini watersheds of Gagar watershed may be calculated to obtain prioritization rating. Mini watershed with the lowest compound parameter value will receive the highest priority (one). Highest value of priority ranking indicates the greater degree of erosion in the particular mini watershed and it becomes potential area for applying soil conservation measures. REFERENCES Gottschalk,. C. (1964). Handbook of pplied Hydrology, (Chow V T. ed.), McGraw Hill Book Company, New York. Horton, R. E. (1945). Geological Society of merican Bulletin., 56: Javed,. et al. (2009). J. of the Indian Society of Remote Sensing., 37: Kar, G. et al. (2009). gricultural Water Management., 96: Melton, M.. (1958). Journal of Geology., 66: Nag, S. K. (1998). Journal of Indian Society of Remote Sensing., 26: Schumn, S. (1956). Res. Bulletin: Geological Society of merica. 67: , Boulder, United States. Singh, S. and Singh, M. C. (1997). National Geographical Journal of India., 43: Somashekar, R. et al. (2011). J. of the Indian Society of Remote Sensing., 39: Srinivasa, V. S. et al. (2004). Journal of Indian Society of Remote Sensing., 32: Strahler,. N. (1957). Handbook of pplied Hydrology, (Chow V T. ed.), McGraw Hill Book Company, New York. Thakkar,. K. and Dhiman, S. D. (2007). Journal of the Indian Society of Remote Sensing., 35: