MORPHOMETRIC ANALYSIS OF WATERSHEDS IN THE KUNIGAL AREA OF TUMKUR DISTRICT, SOUTH INDIA USING REMOTE SENSING AND GIS TECHNOLOGY PROJECT REFERENCE NO. : 37S1170 COLLEGE : SIDDAGANGA INSTITUTE OF TECHNOLOGY, TUMKUR BRANCH : CIVIL ENGINEERING GUIDE : DR.NANDEESH STUDENTS : ABHISHEK BOTHRA ANISH KHADKA VIKAS.S.R Keywords: Morphometric analysis, Arc GIS Ver 9.2, ArcMap, Erdas Imagine Ver 9.1, Digital Elevation Model (DEM). Introduction: Morphometry is the measurement and mathematical analysis of the configuration of the earth's surface, shape and dimension of its landforms.the morphometric analysis of the drainage basin and channel network play an important role in understanding the geohydrological behavior of drainage basin and expresses the prevailing climate, geology, geomorphology, structural background of the catchment. The drainage basin analysis is important in any hydrological investigation as assessment of groundwater potential, groundwater management and environmental assessment.various important hydrologic phenomena can be correlated with the physiographic characteristics of drainage basins such as size, shape, slope of drainage area, drainage density, size and length of the contributories etc. Geology, relief and climate are the primary determinants of running water systems functioning at the basin scale. Geographical Information System (GIS) techniques are now-adays in use for assessing various terrain and morphometric parameters of the drainage basins and watersheds, as it provide a flexible environment and an important tool for the manipulation and analysis of spatial information. Kunigal is a town located in southern 1
Tumkur district, Karnataka state, India. Kunigal Taluk is bounded by Latitude N 12044 38.74 to1308 1.16 and longitude E 76049 43 to 7709 57, where as Kunigal town is located at 13.020 N and 77.030 E. The study area is covered under Survey of India (SOI) Toposheet numbers 57C/16, 57G/4, 57D/13, 57H/1, 57H/2 (Scale 1:50,000). Objectives: To understand and analyse various morphometric parameters like Drainage Network -Stream Order, Stream Number, Stream Length, Bifurcation Ratio, etc. Basin Geometry - Basin Length, Basin Area, Basin Perimeter, Drainage Texture, Circularity Ratio, Elongation Ratio, etc. Drainage Texture Analysis - Stream Frequency, Drainage Density, Drainage Pattern, Length of Overland Flow, etc. Relief Characteristics - Height of Basin Mouth, Maximum Height of the Basin, Total Basin Relief, Ruggedness Number, etc. by using topographic maps and satellite image. Creation of Digital Elevation Model (DEM) and deriving its parameter. Understanding the morphometric behaviour of the study area. Methodology: The drainage map of Kunigal taluk is traced from the toposheets published by the Survey of India (SOI) of scale 1:50,000. Different thematic maps are created, showing tanks, drainage and contour using software s like Arc GIS Ver9.2, Arc view Ver9.2, ERDAS imagine Ver.9.1 etc. The morphometric studies are carried out using GIS software. Details of drainage network, basin geometry drainage texture analysis and relief characteristic are shown in below table. Sl. No. Morphometric Parameter Formula Reference A ) Drainage Network 1 Stream Order(Su) Hierarchical Rank Strahler(1952) 2 1st Order Stream (Suf) Suf = N1 Strahler (1952) 3 Stream Number (Nu) Nu= N1+N2+ Nn Horton(1945) 2
4 Stream Length (Lu) Kms Lu= L1+L2 Ln Strahler (1964) 5 Stream Length Ratio (Lur) Lur= Lu / (Lu 1) Strahler (1964) 6 Mean Stream Length Ratio Lurm=Average of Mean Stream Horton (1945) (Lurm) Length ratios of all orders 7 Weighted Mean Stream Luwm=(Lur*Lur-r)/Lur-r Horton (1945) Length Ratio (Luwm) Lur-r: Stream length used in the ratio of all order. 8 Bifurcation Ratio (Rb) Rb = Nu / (Nu + 1) Strahler (1964) 9 Mean Bifurcation Ratio (Rbm) Rbm=Average of bifurcation ratios of all orders. Strahler (1964) 10 Weighted Mean Bifurcation Ratio (Rbwm) Rbwm = (Rb*Nu-r)/Nu-r Nu-r: No. of streams used in Ratio of all order. 11 Rho Coefficient (ρ) ρ = Lur / Rb Horton (1945) B ) Basin Geometry 12 Basin Length (Lb) Kms Software (ArcGIS9.2) Schumm(1956) 13 Basin Area (A) Sq Kms Software (ArcGIS9.2) Schumm(1956) 14 Basin Perimeter (P) Kms Software (ArcGIS9.2) Schumm(1956) 15 Length Area Relation Lar = 1.4 * A 0.6 Hack (1957) (Lar) 16 Lemniscate s (k) k = Lb2/ A Chorley (1957) 17 Form Factor Ratio (Rf) Ff = A / Lb2 Horton (1932) 18 Texture Ratio (Rt) Rt = N1 / P Schumm(1956) 19 Circularity Ratio (Rc) Rc = 12.57 * (A / P2) Miller (1968) 20 Drainage Texture (Dt) Dt = Nu / P Horton (1945) 21 Compactness Coefficient Cc = 0.2841 * P / A 0.5 Gravelius (1914) (Cc) 22 Elongation Ratio (Re) Re = 2 / Lb * (A / π)0.5 Schumm(1956) C ) Drainage Texture Analysis 23 Stream Frequency (Fs) Fs = Nu / A Horton (1932) 24 Drainage Density (Dd) Dd = Lu /A Horton (1932) Km / Kms2 25 Drainage Intensity (Di) Di = Fs / Dd Faniran (1968) 26 Infiltration Number (If) If = Fs * Dd Faniran (1968) 27 Drainage Pattern (Dp) Inference Horton (1932) 28 Length of Overland Flow Lg = A / 2 * Lu Horton (1932) (Lg) Kms 29 Constant of Channel Maintenance (Kms2/ Km) C = 1 / Dd Schumm(1956) D ) Relief Characteristics 30 Contour interval GIS Analysis 20m Interval 31 Height of Basin Mouth (z) GIS Analysis /DEM - - 3
m 32 Maximum Height of the GIS Analysis /DEM - Basin (Z) m 33 Total Basin Relief (H) m H = Z z Strahler (1952) 34 Relief Ratio (Rhl) Rhl = H / Lb Schumm(1956) 35 Relative Relief Ratio Rhp = H * 100 / P Melton (1957) (Rhp) 36 Ruggedness Number (Rn) Rn = Dd * (H / 1000) Patton & Baker (1976) Results and Conclusion: The study area has been delineated into several small watersheds based on the area. Based on the guidelines provided by Watershed Atlas of India, 1990 the area has been subdivided into micro, milli and sub-watersheds. There are 8-micro, 18-milli and 1 sub watersheds. The morphometric elements like mean length, mean area, drainage density etc. was calculated by statistical methods. The study area has stream order ranging from two to maximum of fifth order. It is observed that the maximum frequency is in case of first order streams. It is also noticed that there is a decrease in stream frequency as the stream order increases. The drainage networks of all watersheds exhibits the dendritic drainage pattern and the variation in stream length ratio might be due to changes in slope and topography. The weighted bifurcation ratio ranges from 3.078-5.490 reveals that the drainage network in the study area is well developed stage. The drainage density of the area ranges from 0.836 3.058 km/km2 indicates that region has highly permeable subsoil and dense vegetation cover. Drainage density is very coarse to moderate texture. The stream frequencies for all watersheds of the study exhibits positive correlation with the drainage density values indicating the increase in stream population with respect to increase in drainage density. Elongation ratio and circulatory ratio shows that most of Kunigal watershed possesses circular shape, while the remaining elongated pattern. In the present study, the higher values of Rb indicates strong structural control on the drainage pattern while the lower values indicative of sub watersheds that are not affected by structural disturbances. 4
The value of relief ratio is between 0.010 and 0.047. It has been observed that areas with low to moderate relief and slope are characterized by moderate value of relief ratios. Low value of relief ratios are mainly due to the resistant basement rocks of the basin and low degree of slope. The low ruggedness value of watershed implies that area is less prone to soil erosion and have intrinsic structural complexity in association with relief and drainage density. The Remote Sensing and GIS techniques have become indispensable management tool for efficient management of natural resources even at micro-watershed level. Scope for future work: Remotely sensed data for the thematic maps have to be prepared annually by digital interpretation for the accuracy of the mapping for surface and ground water resources. For estimation of runoff, the land use / land cover was assumed to be same for all the year. Hence, land use / land cover map has to be updated for accurate runoff estimation. Tanks in the study area have to be studied with respect to the water spread area and sedimentation taken up in the water bodies due to soil erosion in the watershed area. Collection of more Ground Control Points (GCP) using GPS. 5