INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 4, No 1, 2013

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1 INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 4, No 1, 2013 Copyright 2010 All rights reserved Integrated Publishing services Research article ISSN Quantitative Morphometric analysis of Kosasthalaiyar sub basin (Chennai basin) using remote sensing (SRTM) data and GIS techniques Vibhu Nayar 1, Kavitha Natarajan 2 1- Founder Mentor, Center of Excellence for Change, III Floor, Chief Architect Building, PWD Complex, Chepauk, Chennai GIS and Water Specialist, Center of Excellence for Change, III Floor, Chief Architect Building, PWD Complex, Chepauk, Chennai kavitha.natarajan.p@gmail.com ABSTRACT The growing competition demand for water from industrial, domestic, and environmental sectors, along with increasing intensity of quality and quantity challenges as a result of rapid urbanization, call for scientific approaches to water resource management. Drainage basins, catchments and sub catchments are the hydrological units ideally suited for planning purposes focused on conserving land and water resources. The availability of remote sensing data and enabling GIS platform lend scope for understanding the morphometric properties of the catchment area and surface drainage characteristics of many river basins in different parts of the globe. Kosasthalaiyar sub basin with an area of km 2 playing a vital role for the water supply, food security and economic development of Chennai city was taken up for the study. SRTM data and Arc GIS 10, spatial analyst tools along with arc hydro tools were used for morphometric analysis of the sub basin to derive linear, relief, and aerial aspects. Strahler stream ordering techniques and analysis were followed for further analysis. The results revealed that the elongated sub basin is reasonably homogeneous in geology without structural disturbances with low relief and moderate to gentle slope in all the constituent subwatersheds. The low drainage density is because of the highly permeable subsoil, with good permeability of sub-surface material and dense vegetative cover with low relief. The overland flow is significantly affected by infiltration and percolation through the soil, both varying in time and space. The analysis output leads to the conclusion that structural interventions are needed to improve the surface storage and landuse modifications for better water management. Keywords: SRTM data, GIS techniques, Morphometric analysis, Kosasthalaiyar sub basin. 1. Introduction Given India s burgeoning population, the water crisis has reached critical levels. Growing demands for water resources from industrial, domestic, and environmental sectors, along with increasing quality and quantity issues as a result of rapid urbanization, have made water resource management imperative in India. As the opportunity costs of water increase, and management of water resources and their allocation among competing demands assumes vital importance, demand management must indubitably receive preference over traditional supply management (Rajagopal, 2007). Drainage basins, catchments and sub catchments are the hydrological units for planning purposes to conserve natural resources. The watershed management concept recognizes the interrelationships and the linkages between the topography, landuse, geomorphology, slope and soil. Soil and water conservation is the key issue in watershed management. However, while considering watershed conservation work, it Submitted on June 2013 published on August

2 is not feasible to take the whole area at once. Thus the whole basin is divided into several smaller units, as sub watersheds or micro watersheds, by considering its drainage system (Sangita Mishra and Nagarajan, 2010). The morphometric analysis of the drainage basin and channel network play a vital role in understanding the geo-hydrological behavior of drainage basin and expresses the prevailing climate, geology, geomorphology, structural, etc. antecedents of the catchment. The relationship between various drainage parameters and the aforesaid factors are well recognized and recently, the availability of remote sensing (RS) data and enabling Geographical Information System (GIS) platform for understanding the morphometric properties of the catchment area and surface drainage characteristics of many river basins in different parts of the globe. (Horton, 1945; Strahler, 1957; Melton, 1958; Morisawa, 1959; Krishnamurthy et.al., 1996; Agarwal, 1998; Pakhmode et.al., 2003; Gangalakunta, et.al., 2004; Nag, 1998; Das and Mukherjee, 2005). 2. Advantage of using SRTM data and GIS techniques in Morphometric analysis Morphometric analysis is an important aspect of hydrological and hydrogeological studies (Agarwal et.al., 2000). It helps to understand the hydrological characters and the results will be useful input for a comprehensive water resource management plan (Jawahar raj et.al., 1998; Kumaraswami et.al., 1998 and Sreedevi et.al., 2001). Morphometric studies in the field of hydrology were first initiated by Horton (1940) and Strahler (1950). Morphometric analysis requires measurement of the linear features, gradient of channel network, and contributing ground slopes of the drainage basin. It is a significant tool for prioritization of sub watersheds even without considering the soil map (Biswas et.al., 1999). For morphometric analysis RS and GIS techniques were used for watershed prioritization, sub watershed analysis and management and also many research reports have been reported (Srinivasa et.al., 2004, Chopra et.al., 2005, Khan et.al., 2001, Nookaratnam et.al., 2005). Major advantages of RS and GIS techniques are its rapid access to latest spatial information over a large geographical area including inaccessible areas, at a relatively economical cost with high degree of precision. It helps to develop base maps even in the absence of field survey, which is user friendly, scalable and flexible at a shortest possible time. The present study is in a complex sub basin and the analysis was challenging but with results confirming the reality. 3. Study area Kosasthalaiyar sub basin is located between the latitudes and longitudes of to N and to E with an area of km 2 (Figure-1). It is one of the eight sub basins in Chennai basin and lies almost at the centre of Chennai basin in between Araniyar and Coovam Sub basin. This Sub-basin has a sub-tropical climate. The temperature in the plains has a minimum of C and a maximum of C. The average normal rainfall of the District is 1104 mm. Out of which 52% is received during north east monsoon period and 41% during south west monsoon period. The Kosasthalaiyar River (Kortalaiyar) originating near Kaveripakkam (Vellore District) is one of the three rivers that flows in the Chennai Metropolitan area (North East direction) and drains into the Bay of Bengal. A branch of the river from Kesavaram Anicut flows to the city as Coovam River and the main Kosasthalaiyar River flows to Poondi reservoir. From Poondi reservoir, the river flows through Thiruvallur District, enters the Chennai metropolitan area, and joins the sea at Ennore creek. There are two check dams across the river at Tamaraipakkam and Vallur. The 90

3 excess discharge in the river is controlled by the Tamarapakkam Anicut located across the river in the downstream of Poondi reservoir. Vallur Anicut is a small check dam constructed near Minjur across the river to control water levels and feed irrigation channels in the area. It flows to a distance of 16 km in the Chennai metropolitan area (CMA Report). Figure-1 Location map of the Kosasthalaiyar sub basin 4. Data used and methodology adopted for the study Quantitative analysis of morphometric parameters for the present study is done using the Digital Elevation Model (DEM) from the Shuttle Radar Topographic Mission (SRTM) of 90m resolution data (GLCF, 2000). Arc GIS 10, spatial analyst tools and Arc hydro tools were used for the sub basin delineation and further analysis of the morphometric parameters of the sub basin like linear, topographic, relief and aerial aspects. Strahler stream ordering technique was followed for stream ordering and other mathematical formulae were followed for further analysis using various methods. 5. Results - Morphometric analysis and output Morphometery the mathematical analysis of the configuration of the earth's surface shape and dimensions of its landform provides the basis of the investigation of the watershed (Clarke, 1996). The area, altitude, volume, slope, profile and texture of landforms comprise principal parameters of investigation. Dury (1952), systematic description of the geometry of a drainage basin and its stream channel requires measurement of linear aspects of the drainage network, aerial aspects of the drainage basin, and relief (gradient) aspects of the channel network and contributing ground slopes Strahler (1964). The overall output of the morphometric analysis of the Kosasthalaiyar sub basin is represented in Figure-2 91

4 5.1 Morphometric analysis of the Kosasthalaiyar sub basin Linear aspects The Kosasthalaiyar morphometric analysis of the linear aspects includes stream order, stream length, mean stream length, stream length ratio and bifurcation ratio (Table-1). 1. Stream order (Su) Stream ordering is the first step in quantitative analysis of watershed expresses the hierarchical relationship between stream segments, their connectivity and the discharge arising from contributing catchments. In the present study, stream ordering has been carried out using Strahler method (1964). Kosasthalaiyar sub basin is characterized upto VI order stream network. It is observed that the maximum frequency is in the case of first order streams and that there is a decrease in stream frequency as the stream order increases. Figure 2: Morphometric analysis output of Kosasthalaiyar Sub Basin using SRTM data 92

5 Stream Order Table 1: Morphometric analysis of Kosasthalaiyar sub basin - Linear aspects No of Streams Length of stream (km) Log N u Log L u Bifurcation ratio Stream Length Ratio No of streams used in Ratio S u N u L u R b R l I Order II Order III Order IV Order V Order VI Order Total Mean Stream Number (Nu): The total of order wise stream segments is known as stream number. Horton (1945) states that the numbers of stream segments of each order form an inverse geometric sequence with order number. Total and mean stream number of Kosasthalaiyar sub basin is 1340 and Total log value is Stream Length (Lu): Stream length is computed based on the Horton law (1945). Kosasthalaiyar sub basin I order streams have the maximum length (1416.2km) compared to that of other orders. It decreases as stream order increases. The total length, mean length and total log value of the stream in Kosasthalaiyar sub basin is about km, 468.4km and Stream Length Ratio (Rl): The mean stream length is calculated by dividing the total stream length of given order by number of stream of that order. Mean stream length of the Kosasthalaiyar sub basin is about Generally its value of the given order is greater than that of the lower order and less than that of its next higher order. Changes in Rl from one order to another indicate the late youth to mature stage of the geomorphic development (Singh and Singh, 1997). 5. Bifurcation ratio (Rb): Bifurcation ratio is the ratio of the number of stream segments of given order to the number of segments of next higher order. It is an index of relief and dissection (Horton, 1945 and Schumm, 1956). Total and mean Bifurcation ratio of the Kosasthalaiyar sub basin is and It has been found that the bifurcation ratio characteristically ranges between 3 and 5 for watershed in which geology is reasonably homogeneous without structural disturbances to the drainage basin. 5.2 Morphometric analysis of the Kosasthalaiyar sub basin Geometric aspects Generally sub basin geometry is characterized by various factors among them the important factors are the sub basin area (A), perimeter (P), length (Lb), relative perimeter (Pr), mean width (Wb), length area relation (Lar), lemniscate (k), form factor ratio (Rf), elongation ratio (Re), drainage texture (Dt), texture ratio (Rt) and circularity ratio (Rc). Geometric aspects values of Kosasthalaiyar sub basin aspects is represented in table 2. 93

6 Table 2: Morphometric analysis of Kosasthalaiyar sub basin - Geometric aspects No Geometric - Parameters Formula Method Result 1. Area (km 2 ) A GIS output Arc GIS Perimeter (km) P GIS output Arc GIS Length (km) L u GIS output Arc GIS Relative perimeter (P r) P r = A/P Schumn(1956) Mean width (W b) W b = A/L b Horton (1932) Length area relation km (L ar) L ar = 1.4*A 0.6 Hack (1957) Lemniscate (k) k = L b2 / A Chorley (1957) Form factor ratio (R f) R f = A / L b 2 Horton (1932) Elongation ratio (R e) R e = 2/ L b*(a/π) 0.5 Schumn (1956) Drainage texture (D t) D t = N u/ P Horton (1945) Texture ratio (R t) R t = N u/ P Schumn (1956) Circularity ratio (R c) R c = 4* π (A/P 2 ) Miller (1953) Centre of gravity of the sub basin (G c) GIS output Arc GIS N E 1. Area of the sub basin (A): The area of the watershed is another important parameter like the length of the stream drainage. Schumm (1956) established an interesting relation between total watershed area and total stream length, which are supported by the contributing area. Area of the Kosasthalaiyar sub basin is km 2. Basin area is the direct outcome of the drainage development in a particular basin. It is usually seen that the basin is pear shaped in early stages, but as the cycle advances, the shape tends to become more elongated (Padmaja Rao, 1978). 2. Perimeter of the sub basin (P): Basin perimeter is the outer boundary of watershed that enclosed its area. It is measured along the divides between watersheds and may be used as an indicator of watershed size and shape (Schumm, 1956). The perimeter and relative perimeter of the Kosasthalaiyar sub basin is km and 5.11km. 3. Length of the sub basin (Lb): Horton (1932) defined basin length as the straight-line distance from a basin mouth to the point on the water divide intersected by the projection of the direction of the line through the source of the main stream, the length of the Kosasthalaiyar sub basin is arrived as km. 4. Length area relation (Lar): Hack (1957) found that for a large number of basins, the stream length and basin area are related by simple power functions. The length area relation of the Kosasthalaiyar sub basin is Lemniscate (k): Chorley (1957), express the lemniscate s value to determine the slope of the basin. The lemniscate (k) value for the Kosasthalaiyar sub basin is Form factor ratio (Rf): Horton (1932), form factor may be defined as the ratio of basin area to square of the basin length. The value of form factor would always be less than (for a perfectly circular watershed). The form factor ratio of Kosasthalaiyar sub basin is a Elongation ratio (Re): The shape of the basin is conveyed by the elongation ratio. Schumm (1956) elongation ratio is the ratio of diameter of a circle of the same area as the drainage basin and the maximum length of the basin (Strahler states that this ratio 94

7 runs between 0.6 and 1.0 over a wide variety of climatic and geologic types. The varying slopes of watershed can be classified with the help of the index of elongation ratio, i.e. circular ( ), oval ( ), less elongated ( ), elongated ( ), and more elongated (< 0.5). These values are further categorized as circular (>0.9), oval ( ) and less elongated (<0.7). The elongation ratio of Kosasthalaiyar sub basin is Drainage texture (Dt): Horton s (1945) drainage texture is considered as one of the important concept of geomorphology which shows the relative spacing of the drainage lines. Smith (1939) classified drainage texture into five different textures i.e., very coarse (<2), coarse (2 to 4), moderate (4 to 6), fine (6 to 8) and very fine (>8).The drainage texture value of the Kosasthalaiyar sub basin is Texture ratio (Rt): Schumm (1963) texture ratio is an important factor in the drainage morphometric analysis which is dependent on the underlying lithology, infiltration capacity and relief aspect of the terrain. Texture ratio of the Kosasthalaiyar sub basin is 1.84 and categorized as low in nature. 10. Circularity ratio (Rc): Miller s (1953) Circularity ratio is the ratio of the basin area to the area of a circle having the same circumference perimeter as the basin, which is dimensionless and expresses the degree of circularity of the basin. The circularity ratio of the Kosasthalaiyar sub basin is Centre of gravity of the sub basin (Gc): It is the length of the channel measured from the watershed to a point on the stream nearest to the centre of the watershed. Centre of gravity of the Kosasthalaiyar sub basin is located at the latitude and longitude of N and E. 5.3 Morphometric analysis of the Kosasthalaiyar sub basin Relief aspects The relief aspects determined basin relief (H), relief ratio (Rh), relative relief (Rhp) and ruggedness number (Rn). Kosasthalaiyar sub basin analysis output of the relief aspects is represented table 3. Table 3: Morphometric analysis of Kosasthalaiyar sub basin - Relief aspects No Relief - Parameters Formula Method Result 1. Basin Relief (H) H = Z-z Strahler (1957) Relief Ratio (R h) R h = H / L b Schumm (1956) Relative Relief (R hp) R hp = H*100/P Melton (1957) Ruggedness Number (R n) R n= D*( H/1000) Strahler (1957) Basin Relief (H): Strahler (1957) defined the total relief of the river basin as the difference in the elevation between the highest point of a watershed and the lowest point on the valley floor. The Kosasthalaiyar sub basin relief is Relief Ratio (Rh): Schumm s (1954) relief ratio is obtained when basin relief H is divided by the maximum basin length (Lb) which results in a dimensionless ratio which is equal to the tangent of the angle formed by two planes intersecting at the mouth of the basin called relief ratio which measures the overall steepness of a drainage basin and it is an indicator of the intensity of erosional process operating on 95

8 slope of the basin. The overall relief of Kosasthalaiyar sub basin is 2.97 which indicate low relief and moderate to gentle slope. 3. Relative Relief (Rhp): Melton s (1957) maximum basin relief was obtained from the highest point on the watershed perimeter to the mouth of the stream. The relative relief of the Kosasthalaiyar sub basin is Ruggedness number (N): Strahler s (1956) ruggedness number is the product of maximum basin relief and drainage density, where both parameters are in the same unit. An extreme high value of ruggedness number occurs when both variables are large and the slope is not only steep but long as well. The value of ruggedness number of the Kosasthalaiyar sub basin is It is low which indicates gentle slope for subwatersheds. 5.4 Morphometric analysis of the Kosasthalaiyar sub basin Aerial aspects The aerial aspects generally include stream frequency (Fs), drainage density (Dd), drainage pattern (Dp), drainage intensity (Di), constant of channel maintainace (C), infiltration no (If) and Length of overland flow (Lg) of the sub basin. Basin area is hydrologically important because it directly affects the size of the storm hydrograph, magnitudes of peak and mean runoff. It is interesting that the maximum flood discharge per unit area is inversely related to the size (Chorley et.al., 1957). The drainage texture analysis and output of Kosasthalaiyar sub basin is summarized in table Stream Frequency (Fs): Horton s (1932) stream frequency is defined as the total number of stream segments of all orders per unit area. The stream frequency of the Kosasthalaiyar sub basin area is Greater the drainage density and stream frequency in a basin, the runoff is faster, and therefore, flooding is more likely in basins with a high drainage and stream frequency (Kale, 2001). 2. Drainage Density (D): Horton s (1932) drainage density is an important indicator of the linear scale of landform element in stream eroded topography and defines as the total length of stream of all orders/drainage area. The drainage density indicates the closeness of spacing of channels, thus providing a quantitative measure of the average length of stream channel for the whole basin. The drainage density of the Kosasthalaiyar sub basin is about Drainage Pattern (Dp): Drainage pattern is a factor of slope lithology and structure and also it helps in identifying the stage of cycle of erosion. Howard (1967) related drainage patterns to geological information. It is possible to deduce the geology of the basin, the strike and dip of depositional rocks, existence of faults and other information about geological structure from drainage patterns. Kosasthalaiyar sub basin is having dendritic type of drainage pattern. 4. Drainage Intensity (Di): Faniran (1968) defines the drainage intensity as the ratio of the stream frequency to the drainage density. Drainage intensity of the Kosasthalaiyar sub basin is Constant of Channel Maintenance (C): Schumm (1956) used the inverse of drainage density or the constant of channel maintenance as a property of landforms. The constant of channel maintenance indicates the relative size of landform units in a 96

9 drainage basin and has a specific genetic connotation (Strahler, 1957). Constant channel maintenance of the Kosasthalaiyar sub basin is Infiltration Number (If): Infiltration number of a drainage basin is the product of drainage density and stream frequency. It is the number by virtue of which an idea regarding the infiltration characteristics of the basin is obtained. Kosasthalaiyar sub basin has the infiltration number of The higher the infiltration number, the lower will be the infiltration and higher will be the run-off (Rao Liaqat et.al., 2011). 7. Length of Overland Flow (Lg): Length of overland flow is one of the most important independent variable affecting both hydrologic and physiographic development of drainage basins and relates reciprocally to the average slope of the channel and is quiet synonymous with the length of sheet flow to a large extent. It is defined as the length of flow path, projected to the horizontal, non channel flow from point on the drainage divide to a point on the adjacent stream channel. This term refers to the length of the run of the rainwater on the ground surface before it is localized into definite channels (Horton, 1945). Length of overland flow of the Kosasthalaiyar sub basin is Table 4: Morphometric analysis of Kosasthalaiyar sub basin - Drainage texture No Morphometric Parameters Formula Method Result 1. Stream frequency (F s) F s = N u / A Horton (1932) Drainage density (D d) D d = L u / A Horton (1932) Drainage Pattern (D p) GIS output Arc GIS 10 Dendritic 4. Drainage Intensity (D i) D i= F s / D d Faniran (1968) Constant of Channel Maintainace (C) C = 1 / D d Schumn (1956) Infiltration No (I f) I f = F s * D d Faniran (1968) Length of overland flow (L g) L g = A/2 * L u Horton (1945) Discussion - Morphometric analysis The critical morphometric characteristics of a drainage basin which influence the drainage functions are discussed here. Kosasthalaiyar sub basin bifurcation ratio indicates that the geology is reasonably homogeneous without structural disturbances to the drainage basin. Higher value of the bifurcation ratio indicates some sort of geological control and lower indicates that the basin produces a sharp peak in discharge and if it is high, the basin yields low, but extended peak flow (Agarwal, 1998). In well developed drainage network the bifurcation ratio is generally between 2 to 5 (Horton, 1945 and Strahler, 1964). Circularity ratio of the Kosasthalaiyar sub basin indicates that the sub basin is elongated in shape. It bears an inverse relation to the basin area (Zavoiance, 1985). It is influenced more by the length, frequency and gradient of streams of various orders rather than slope conditions and drainage pattern of the basins. The elongation ratio of the Kosasthalaiyar sub basin value indicates that it is more elongated in shape and the same is confirmed by the form factor ratio. A circular basin is more efficient in discharge of run-off than that of an elongated basin (Singh and Singh 1997). The watershed with high form factors have high peak flows of shorter duration, whereas elongated watershed with low form factor will have a flatter peak of flow for longer duration. The drainage texture value of the Kosasthalaiyar sub basin clearly indicates that it has coarse texture category. 97

10 Drainage density value of Kosasthalaiyar sub basin indicates that it has highly permeable subsoil, dense vegetative cover and low relief (Nag, 1998). It has been observed that this measurement made over a wide range of geologic and climatic types that a low drainage density is more likely to occur in regions of highly resistant of highly permeable subsoil material under dense vegetative cover, and where relief is low. Low drainage density leads to coarse drainage texture while high drainage density leads to fine drainage texture (Strahler, 1964). High drainage density is the resultant of weak or impermeable subsurface material, sparse vegetation and mountainous relief. The low drainage density is also indicative of relatively long overland flow of surface water; it is also related to the climate, surface roughness and runoff of the area. The type of rock also affects the drainage density. Generally, lower values tend to occur on granite, gneiss and schist regions. Kosasthalaiyar sub basin has dendritic pattern, which is most common pattern formed in a drainage basin composed of fairly homogeneous rock without control by the underlying geologic structure. In a dendritic system, there are many contributing streams, which join together into the tributaries of the main river. They develop where the river channel follows the slope of the terrain (Lambert david, 1998). The longer the time of formation of a drainage basin is, more easily the formation of dendritic pattern. Kosasthalaiyar sub basin has low value of drainage intensity that implies that the drainage density and stream frequency have little effect on the extent to which the surface has been lowered by agents of denudation. With these low values of drainage density, stream frequency and drainage intensity, surface runoff does not happen quickly from the watershed, making it highly susceptible to flooding. Kosasthalaiyar sub basin has low value of relief ratios are mainly due to the resistant basement rocks of the basin and low degree of slope (Kuldeep pareta and Upasana pareta, 2011) and low ruggedness value of the watershed implies that area is less prone to soil erosion and have intrinsic structural complexity in association with relief and drainage density. The higher the infiltration number the lower will be the infiltration and higher will be the run-off and length of overland flow indicates low surface runoff flow. Overland flow is significantly affected by infiltration and percolation through the soil, both varying in time and space (Schmid, 1997). Even though Kosasthalaiyar sub basin morphometric parameters are favorable for run-off and infiltration, floods occur during heavy rainfall especially during north east monsoon which is characterized by high intensity, short duration rainfall. This is mainly due to the inefficiency of the surface storage facilities like reservoirs, tanks and degeneration of streams and landuse changes due to urban impact. The discharge capacity of the Kosasthalaiyar River is 110,000 m 3 /s and the anticipated flood discharge capacity is about 125,000 m 3 /s (Lakshmi, 2011). Every year, whenever the floodgates of Poondi reservoir are opened, a considerable volume of water gets drained into the sea through the Kosasthalaiyar River near the Ennore creek. 7. Conclusion The quantitative morphometric analysis using SRTM data and GIS techniques is a simple economical and time saving methodology to study the river basin with an output of good quality and high degree of accuracy. Kosasthalaiyar sub basin geology is reasonably homogeneous without structural disturbances which is elongated in shape and hence will have a flatter peak of flow for longer duration lower efficiency in discharge of run-off. This sub basin has coarse drainage texture. The stream frequency and drainage density of this sub basin indicate clearly the high permeable subsoil, dense vegetative cover and low relief. 98

11 It is an indication of relatively long overland flow of surface water; which is also related to the climate, surface roughness and runoff of the area. This sub basin has a dendritic type of drainage pattern composed of fairly homogeneous rock and does not interface with the underlying geologic structure. Low values of drainage density, stream frequency and drainage intensity indicate that the surface runoff is not quickly removed from the watershed, making it highly susceptible to flooding, soil erosion and movements. This sub basin has the low infiltration number which indicates high infiltration and low surface run-off which is confirmed by the length of overland flow. Even though Kosasthalaiyar sub basin morphometric parameters are favorable for run-off and infiltration floods occur during heavy rainfall this is mainly due to the inefficiency of the surface storage facilities like reservoirs, tanks and degeneration of streams and landuse changes due to urban impact. 8. Recommendation All the above outputs clearly lead to the conclusion that the Kosasthalaiyar sub basin has the potential to perform its drainage function more effectively. Increasing the storage capacity of the water bodies, rehabilitation and restoring channels to standards will enhance the sub basins water holding capacity which will be of immense use to meet the urban water demands of the Chennai city apart from meeting the agriculture, domestic and industrial demands. 9. References 1. Agarwal, C.S., (1998), Study of drainage pattern through aerial data in Nahagarh area of Varansi district, U.P. J. Indian Soc. remote sensing 26 (4), pp Biswas, S., Sudhakar, S. and Desai, V. R., (1999), Prioritisation of subwatersheds based on morphometric analysis of drainage basin: A remote sensing and GIS approach, Journal of Indian society of remote sensing, 27(3), pp Chopra, R., Dhiman, R., and Sharma, P. K., (2005), Morphometric analysis of subwatersheds in Gurdaspur district, Punjab using remote sensing and GIS techniques, Journal of Indian society of remote sensing, 33(4), pp Chorley, R.J., E.G. Donald Malm and H.A. Pogorzelski., (1957), A new standard for estimating drainage basin shape, Amer. Jour. Sci., 255, pp Clarke, J.I., (1966), Morphometry from Maps. essays in geomorphology. Elsevier Publ. Co., New York, pp CMA Report, Session-3 river and drainage system in CMA 7. Das, A.K.and Mukherjee, S., (2005), Drainage morphometry using satellite data and GIS in Raigad district, Maharashtra. Jour. Geol. Soc. India 65, pp Faniran, A., (1968), The index of drainage intensity - A provisional new drainage factor, Aus. Jour. of Sci., 31, pp Gangalakunta, P, Amal, K and Kothiram, S., (2004), Drainage morphometry and its influence on landform characteristics in a basaltic terrain, Central India a remote sensing and GIS approach. Inter. Jour. Appl. Earth and Geoinformation, 6, pp

12 10. GLCF data source: Hack, J. T., (1957), Studies of longitudinal stream profiles in Virginia and Maryland: U. S. geological survey professional paper, 294-B, pp Horton, R.E., (1932), Drainage basin characteristics, Trans. Amer. Geophys. Union, 13, pp Horton, R.E., (1940), An approach toward a physical interpretation of infiltration capacity. Proc. Soil Sci. Soc. Amer. 5, pp Horton,R.E., (1945), Erosional development of stream & their drainage basin, Hydrogeological approach to quantitative morphology. Bull.Geol. Societ. Am 56, pp Howard, A.D., (1967), Drainage analysis in geologic interpretation: a summation. Bulletin of American association of petroleum geology, 51, 22, pp Jawaharraj, N., Kumaraswami, K., and Ponnaiyan, K., (1998), Morphometric analysis of the Upper Noyil basin (Tamil Nadu). Journal of the deccan geographical society, 36, pp Khan, M.A., Gupta, V.P. and Moharana, P.C., (2001), Watershed prioritization using remote sensing and geographical information system: a case study from Guhiya, India, Journal of arid environments, 49, pp Krishnamurthy, J., G. Srinivas, V. Jayaram and M.G. Chandrasekhar., (1996), Influence of rock types and structures in the development of drainage networks in typical hardrock terrain. ITC J., 3-4, pp Kuldeep pareta and upasana pareta (2011), Quantitative morphometric analysis of a watershed of yamuna basin, India using ASTER (DEM) data and GIS, International journal of Geomatics and Geosciences, 2(1), pp Kumaraswamy,K and Sivagnanam N., (1998), Morphometric charecteristics of the vaippar Basin,Tamil Nadu: A qualitative approach, Indian Journal of landscape system and ecological studies, 11(11), pp Lambert, David., (1998), The Field Guide to Geology. Checkmark Books. pp Lakshmi, K., (2011), "WRD plans groynes". The Hindu (Chennai: The Hindu). Retrieved 4-Dec Melton, M.A., (1957), An Analysis of the relations among elements of climate, Surface properties and geomorphology, Project NR , Tech. Rep. 11, Columbia University. 24. Melton, M.A., (1958), Correlation structure of morphometric properties of drainage system and their controlling agents. Jour. Geol., 66, pp

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