INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 2, No 2, 2011

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1 INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 2, No 2, 2011 Copyright 2010 All rights reserved Integrated Publishing services Research article ISSN Prioritization of miniwatersheds based on Morphometric Analysis using Remote Sensing and GIS techniques in a draught prone Bargur Mathur subwatersheds, Ponnaiyar River basin, India Sethupathi A.S 1, Lakshmi Narasimhan C 2, Vasanthamohan V 3, Mohan S.P 4 1 Infosys Technologies Ltd., Bangalore , India 2 Department of Geology, Anna University, Chennai , India 3 Department of Geology, National College, Tiruchirapalli , India 4 Department of Geology, University of Madras, Chennai , India lakshmina_c@yahoo.com ABSTRACT Morphometric analysis has been carried out on 781 sq.km area in the Bargur and Mathur subwatersheds. Based on All India Land area organization norms, the drainage network of the study area has been divided in to 10 miniwatersheds using 1:50,000 scale SOI toposheets and Landsat ETM satellite data. The Morphometric analysis of subwatershed has been carried out using GIS software. The drainage network exhibits dendritic drainage pattern. Stream order ranges from fourth to sixth order. Drainage density varies between 1.26 to 2.94 Km/Km 2. Texture ratio of drainage basins range between 2.59 to 15.46, and the miniwatersheds are classified as moderate to fine drainage texture excepting 4 miniwatersheds which are classified as fine to very fine drainage texture. The stream frequency of Bargur and Mathur subwatersheds ranges between 2.36 to The stream frequency is low in most of the subwatersheds indicating low relief and high permeability, however, four subwatersheds show high stream frequency, indicative of high relief and low infiltration capacity of bedrock. The relief ratio ranges from 0.03 to The bifurcation ratio range from 0.43 to 8.45, with a mean bifurcation ratio of for entire basin, indicates that all miniwatersheds fall under normal basin category. The elongation ratio of miniwatersheds varies from 0.23 to 0.58, indicates miniwatersheds fall under oval and elongated pattern. Present study demonstrates the competence of remote sensing data coupled with GIS techniques in morphometric analysis. Based on the quantitative morphometric analysis, the study area has been classified into highly suitable, moderately suitable and poorly suitable for groundwater prospects. Keywords: Remote Sensing, GIS, Drainage density, Morphometric analysis, Bargur Mathur subwatersheds 1. Introduction Due to erratic rainfall pattern and uncontrolled abstraction, groundwater levels have declined to deeper level. Therefore, watershed management becomes more important for developing the groundwater resources in hard rock areas (Sreedevi et al, 2005). To prepare a comprehensive watershed development plan, it becomes necessary to understand the permeable nature of subsurface, infiltration and runoff status and drainage pattern of the region. Morphometry is the measurement and mathematical analysis of the configuration of the earth s surface, shape and dimensions of its landforms (Clarke, 1966). Submitted on September 2011 published on November

2 Detailed morphometric analysis of a basin is of great help in understanding the influence of drainage morphometry on landforms and their characteristics (Biswas et al., 1999 and Khan et al., 2001). The morphometric analysis can be carried out through measurement of linear, aerial and relief aspects of basin and slope contributions (Nag and Chakraborthy, 2003). The drainage characteristics of Bargur Mathur subwatersheds are studied by analyzing topographical map and Landsat ETM data. In the present study, attempt has been made to evaluate linear, relief and aerial morphometric parameters and analyze soil parameters like porosity, permeability, texture, infiltration, runoff and land erosion conditions. 2. Study Area Figure 1: Base map of the study area The study area is drought prone Bargur Mathur subwatersheds, located in the northern part of Tamil Nadu State in India and is situated between northeastern part of Krishnagiri district and southwestern part of Vellore district (Fig.1). The study area is drained by Bargur and Mathur rivers. These two rivers merge at the southeast corner, where the Pambar river originates and finally joins the river Ponnaiyar. The study area covers an area of 781 sq.km and falls in the Survey of India toposheet numbers 57L/6, 57L/7 and 57L/11 on a scale of 1:50,000. The study area lies between latitudes and and longitudes and The area has a sub tropical climate without any sharp variations. Temperatures vary from 40 o C in summer to around 20 o C in the winter season. The average rainfall is 857mm/yr. Based on the Public Work Department report (2004), these subwatersheds fall under the critical zone, where groundwater discharge is greater than groundwater recharge. Geologically, the study area composed of a wide array of litho units ranging from alkali syenites, ultramafic complexes (such as pyroxenites, gabbros, dunites, carbonatites, syenites, epidote hornblende gneiss, hornblende biotite gneiss and migmatites, high grade metamorphites like charnockite), granitoid gneiss and younger dolerite like intrusives. These rock types represent different time segments within archean era. 404

3 Prioritization of miniwatersheds based on Morphometric Analysis using Remote Sensing and GIS techniques Figure 2: Miniwatersheds and Stream orders classification 3. Methodology The remotely sensed data coupled with topographical data analysis procedures have made satellite sensor data based morphometric analysis a highly effective tool to understand and manage the natural resources (Srinivasan, 1988). Integration of remotely sensed data and GIS provides an efficient way in analysis of morphometric parameters and landform characteristics for resource evaluation, analysis and management (Srinivasa et al., 2004). An attempt has been made to utilize the interpretative techniques of GIS to find out the relationships between the morphometric parameters at miniwatersheds level. The drainage have been delineated using Landsat ETM satellite data on 1:50,000 scale and SOI toposheets have been used as a reference. Based on the All India Landuse organization norms and standards, the study area subwatersheds has been divided into ten miniwatersheds (Fig.2) and ranges in size from 57.2 sq.km to 112 sq.km. The associated drainage networks were digitized using Arc GIS and the stream orders were calculated using the method proposed by Strahler (1964). The morphometric parameters of the miniwatersheds are given in Tables 1 and 2. The linear parameters analyzed include stream order, stream length, stream length ratio and bifurcation ratio. Based on drainage orders, the present study area has been classified as sixth order subwatersheds and the drainage pattern is mostly dendritic type. Other patterns encountered are sub dendritic, parallel, semi parallel and radial types (Fig 2). The number of stream orders has been counted and total length of each order streams has been calculated at miniwatersheds level with the help of GIS software. All aerial parameters, drainage map with 405

4 miniwatersheds have been prepared with the help of Arc GIS software and layouts prepared in Arc view. The miniwatershed has been named based on the tank and villages at the outlet (Table 1). Each miniwatershed is evaluated based on morphometric parameters to categorize into highly suitable, moderately suitable and poorly suitable groundwater prospective zones. 4. Linear Aspect The linear aspects of morphometric analysis such as stream order, stream length, mean stream length, stream length ratio and bifurcation ratio are discussed in the following sections. 4.1 Stream Order In the present study, ranking of streams has been carried out based on the method proposed by Strahler (1964). The stream orders are classified up to six orders in the study area (Fig 2 and Table 2) and it is inferred that the Mathur River III and Bargur River II miniwatersheds only have stream order till 6th order and the remaining miniwatershed has stream orders till 4th and 5th order. The maximum stream order frequency is observed in case of first order streams and then for second order. Hence, it is noticed that there is a decrease in stream frequency as the stream order increases. 4.2 Stream Length The length of a stream is a measure of the hydrological characteristics of the underlying rock surface and the degree of drainage. Wherever the formation is permeable, only a small number of relatively longer streams are formed in a well drained watershed, a large number of streams of smaller length are developed where the formations are less permeable. Generally, the total length of stream segment is the maximum in the first order stream and decreases as the stream order increases. It is inferred from Table 2 that in most of the miniwatersheds, the stream length decreases as stream order increases. However, in case of Kandili, Bargur River II and Mathur River III miniwatersheds, the stream segments length for third, fourth and fifth orders are varies at smaller extent. This change may indicate flowing of streams from high altitude, lithological variation and moderately steep slope (Singh and Singh, 1997). Compared with all miniwatersheds, the stream length is smaller in Mathur River I, Sandur, Penkondapuram, Mathur River II and Kandili miniwatersheds, which indicates permeable nature of subsurface strata. 4.3 Stream Length Ratio Horton (1945) proposed the factor length ratio, which is the ratio of the mean length of a stream if any given order to the mean length of a stream of the next lower order, based on the fact that mean length of a stream of any given order is always greater than the mean length of a stream of the next lower order. The length ratio gives an idea about the relative permeability of the rock formation in a miniwatershed. Horton s law (1945) of stream length states that mean stream length segments of each of the successive orders of a basin tends to approximate a direct geomorphic series with streams length towards higher order of streams. The stream length ratio of the present study area reveals that there is a variation in stream length ratio in each miniwatershed (Table 2). Most of the miniwatersheds show both increasing and decreasing trend in the length ratio from lower order to higher order. In relatively permeable formations, the stream length ratio decreases with increasing stream 406

5 order and this scenario is observed in Mathur River I, Sandur, Penkondapuram, Mathur River II and Kandili miniwatersheds. 4.4 Bifurcation Ratio The term bifurcation ratio may be defined as the ratio of the number of the stream segments of given order to the number of segments of the next higher order (Schumn, 1956). Horton (1945) considered the bifurcation ratio as an index of relief and dissections. Strahler (1957) demonstrated that bifurcation ratio shows a small range of variation for different regions or for different environment except where the powerful geological control dominates. From the bifurcating study (Table 2), it is observed that the bifurcation ratio is not same from one order to its next order. These irregularities are dependent upon the geological and lithological development of the drainage basin (Strahler, 1964). The lower values of bifurcation ratio are characteristics of the miniwatersheds which have suffered less structural disturbances (Strahler, 1964) and the drainage patterns has not been distorted because of the structural disturbances (Nag, 1998). Chow (1964) states that the bifurcation value ranges between 3 to 5 indicates that geologic structures do not exercise a dominant influences on the drainage patterns. It is observed that in all miniwatersheds the drainage patterns are not modified heavily by any major geological controls and except at few miniwatersheds (Mathur River III, Bargur River II, Mathur River II and Kandili) and it is the result of large variation in frequencies between successive orders. In the study area mean bifurcation varies from 0.43 to 8.45; the mean bifurcation of the entire basin is (Table 2). Generally these values are common in the areas where geologic structure does not exercise a dominant influence on the drainage pattern and all miniwatersheds are fall under normal basin category (Strahler, 1957). 4.5 Relief Ratio The elevation difference between the highest and lowest points on the valley floor of a miniwatershed is known as the total relief of that miniwatershed. The relief ratio of maximum relief to horizontal distance along the longest dimension of the basin parallel to the principle drainage line is termed as relief ratio (Schumn, 1956). There is direct relationship between the relief and channel gradient and also a correlation between hydrological characteristics and the relief ratio of a drainage basin (Schumn, 1956). The relief ratio normally increases with decreasing drainage area and size of miniwatershed of a given drainage basin (Gottschalk, 1964). The values of relief ratio are ranging from 0.03 (Penkondapuram) to 0.07 (Maharajagadai RF) in the study area (Table 1). It is observed that the high values of relief ratio indicate steep slope and high relief, while the lower values may indicate the presence of basement rocks that are in the form of small ridges and mounds with lower degree of slope (GSI, 1981). The higher relief ratio value is observed in the Maharajagadai RF, Mathur River 1 and Mathur River II miniwatersheds and high value influences gravity of water flow, low infiltration and high runoff conditions. In the remaining miniwatersheds, the relief ratio is low, generally the low relief ratio indicates less resistant rocks of the area (Sudheer 1986; Sreedevi 1999). 4.6 Aerial Aspect Different morphometric parameters like drainage density, texture ratio, stream frequency, form factor, circularity ratio, elongation ratio and length of overland flow have been discussed in detail in the following sections. 407

6 4.7 Drainage Density The drainage density can indirectly indicate the groundwater potential of an area, due to its relation with surface runoff and permeability. It is defined as the total length of streams of all orders per drainage area (Horton, 1932). Low drainage density generally results in the areas of permeable subsoil material, dense vegetation and low relief (Nag, 1998). High drainage density is the resultant of impermeable subsurface material, sparse vegetation and mountainous relief. Low drainage density leads to coarse drainage texture while high drainage density leads to fine drainage texture. The drainage density analysis is done by two methods, which are drainage density per square grid within the study area and drainage density per miniwatershed and are explained below Drainage density per miniwatershed From the Table 1, it can be inferred that the drainage density value varies between 1.26 and 2.94 Km/Km 2. Only at Maharajagadai RF, Bargur River I, Kandili and Mathur River III miniwatershed shows high drainage density, may be due to the presence of impermeable sub surface material, sparse vegetation and high relief. Whereas remaining miniwatersheds fall under low drainage density indicate the region has highly permeable subsoil and dense vegetation cover. 4.8 Drainage density per square grid The study area is divided in to one square kilometer grids and the total length of drainage streams per square kilometer is assigned to the each grid. Based on the drainage density values, the study area is divided in to three zones (Fig 3), which are high drainage density zone (3 5.8 km/km 2 ), moderate drainage density zone (1.5 3 km/km 2 ) and low drainage density zone (0 1.5 km/km 2 ). Figure 3: Drainage density map of the study area It is observed from the figure 3, that 55% of the study area is occupied with moderate drainage density range, 36 % of the study area is occupied by low drainage density range and 9% of the study area is occupied by high drainage density range. 408

7 Except Maharajagadai RF, Kandili, Bargur River I miniwatershed, all other miniwatersheds are occupied with low and moderate drainage density ranges. 4.9 Stream Frequency Horton (1932) introduced stream frequency or channel frequency which is the total number stream segments of all orders per unit area. A higher stream frequency points to a larger surface runoff and steeper ground surface. Hypothetically, it is possible to have the basin of same drainage density differing in stream frequency and basins of same stream frequency differing in drainage density. From the Table 1, it is observed that the positive correlation with the drainage density values of the miniwatershed indicating the increase in stream population with respect to increase in drainage density. Analysis of stream frequency shows high values in the Maharajagadai RF, Mathur River III, Bargur River I and Kandili miniwatersheds, which are having impermeable subsurface and sparse vegetation and high relief conditions, while remaining miniwatersheds show low stream frequency, indicating high permeable geology and low relief Drainage Texture The drainage texture depends upon a number of natural factors such as climate, rainfall, vegetation, rock and soil type, infiltration capacity, relief and stage of development (Smith, 1950). The soft or weak rocks unprotected by vegetation produce a fine texture, whereas massive and resistant rocks cause coarse texture. Sparse vegetation of arid climate causes finer textures than those developed on similar rocks in a humid climate. The texture of a rock is commonly dependent upon vegetation type and climate (Dornkamp and King, 1971). Drainage lines are numerous over impermeable areas than permeable areas. Drainage texture is the total number of stream segments of all orders per perimeter of that area (Horton, 1945). Horton (1945) recognized infiltration capacity as the single important factor which influences drainage texture and considered drainage texture which includes drainage density and stream frequency. From Table 1, it is observed that the most of the miniwatersheds fall under moderate to fine drainage texture, where as remaining Maharajagadai RF, Bargur River I, Kandili and Mathur River III miniwatersheds fall under fine to very fine drainage texture Form Factor Form factor is be defined as the ratio of basin area to square of the basin length (Horton 1932). From Table 1, it is observed that the form factor varies between 0.17 to 1.03 and analysis of form factor reveals that all miniwatersheds except Mathur River III and Penkondapuram having low form factor value leads to less side flow for shorter duration and high main flow for longer duration and vice versa Circularity Ratio The circularity ratio is the ratio of the area of the basin to the area of a circle having the same circumference as the perimeter of the basin (Miller, 1953). It is a significant ratio, which indicates the dendritic stage of a miniwatershed. Its low, medium and high values are indicative of the youth, mature and old stages of the life cycle of the tributary basins. The high value of the ratio is more influenced by length, frequency and gradient of streams of various orders and further depends on the geological structures, land use / land cover, climate, 409

8 relief and slope of the basin. In the present study, the circularity ratio (Table 1) ranges from 0.25 to High circularity ratio is observed in Varatanapalli, Maharajagadai RF, Penkondapuram miniwatersheds indicate that they are more or less circular in shape and are characterized by high to moderate relief and drainage system is not structurally controlled. The remaining miniwatersheds have less than 0.5 indicating that they are elongated in shape. Table 1: Miniwatersheds geometric and relief / aerial parameters Table 2: Miniwatersheds Linear Parameters Mini water Code Stream Order Count Stream Length I II III IV V VI I II III IV V VI

9 Table 2: Miniwatersheds Linear Parameters (continued) Mini water Code Stream Length Ratio Bifurcation ratio IV/III V/IV VI/V I/II II/III III/IV IV/V V/VI IV/III V/IV VI/V Mean Ratio Elongation Ratio Schumn (1956) defined elongation ratio as the ratio between the diameter of the circle of the same area as the drainage basin and the maximum length of the basin. Analysis of elongation ratio indicates that the areas with higher elongation ratio values have high infiltration capacity and low runoff. A circular basin is more efficient in the discharge of runoff than an elongated basin (Singh and Singh, 1997). The values of elongation ratio generally vary from 0.6 to 1.0 over a wide variety of climate and geologic types. Values close to 1.0 are typical of regions of very low relief, whereas values in the range 0.6 to 0.8 are usually associated with high relief and steep ground slope (Strahler, 1964). These values can be grouped in to four categories namely (a) circular (>0.9), (b) oval (0.9 to 0.80, (c) less elongated (<0.7). The elongation ratio of miniwatersheds of the study area varies from 0.23 to From the Table 1, it is observed that the all miniwatersheds fall under oval and elongated miniwatersheds. Analysis of elongation ratio reveals that the areas with higher elongation ratio values have high infiltration capacity and low runoff Constant of Channel Maintenance Schumn (1956) introduced the factor, constant of channel maintenance, as the inverse of drainage density. It is also the area required to maintain one linear kilometer of stream channel. Generally, a higher constant of channel maintenance of a basin indicates higher permeability of rocks of that basin, and vice versa. This means, 0.34 km 2 is required to maintain one kilometer of stream channel. From the Table 1, it is inferred that the Mathur River 1, Sandur, Penkondapuram, Mathur River II and Bargur River II miniwatersheds are required more than 0.6 Km2 area to maintain one kilometer length stream channel, which in turn indicates that these miniwatersheds are comparatively permeable than remaining miniwatersheds. 411

10 4.15 Length of Overland Flow It is the length of water over the ground before it gets concentrated in to definite streams channels (Horton, 1945). This factor depends on the rock type, permeability, climatic regime, vegetation cover and relief as well as duration of erosion (Schumn, 1956). The length of overland flow approximately equals to half of the reciprocal of drainage density (Horton, 1945). From Table 1, it is observed that the length of overland flow varies from 0.17 to 0.25 and it is less in Maharajagadai RF, Varatanapalli, Bargur River I, Kandili and Mathur River III miniwatersheds as drainage density is high in these miniwatersheds when comparing to remaining miniwatershed. It indicates that miniwatersheds having length of overland flow from 0.17 to 0.25 may be under the influence of high structural disturbance, low permeability, steep to very steep slopes and high surface runoff. Other remaining miniwatersheds having length of overland flow greater than 0.25 are under very less structural disturbance, less runoff conditions and having higher overland flow. A larger value of length of overland flow indicates longer flow path and thus, gentler slopes. 5. Results and Conclusion Based on the morphometric analysis, the miniwatersheds are classified into highly suitable, moderately suitable and poorly suitable for groundwater prospective. 1. The Mathur River I, Sandur and Penkondapuram are classified under highly suitable zone, since these miniwatersheds are characterized by permeable subsurface strata facilitated by well developed coarse drainage texture, less drainage density, less stream length ratio, less bifurcation ratio with longer duration main flow and low relief ratio. 2. The Moderately suitable miniwatersheds for groundwater activities are Varatanapalli, Bargur River I, Mathur River II, Bargur River II, Kandili and Mathur River III are characterized by less permeable nature of geology with moderate infiltration and moderate surface runoff facilitated by high stream length ratio, moderate to low drainage density, coarse to fine drainage texture, combination of high side flow and less main longer duration flow with moderately elevated zone. 3. The Maharajagadai RF miniwatershed classified as not suitable zone for groundwater prospective, since this zone occupied by highly elevated zones with low infiltration and high surface runoff. The morphometric analysis has proven its credential to categorize the Bargur Mathur subwatersheds in to miniwatersheds and delineate groundwater prospective zones as poorly suitable, moderately suitable and highly suitable. Based on the quantitative morphometric analysis, the Mathur River I, Sandur and Penkondapuram miniwatershed are classified into highly suitable zones with respect to high permeable nature of geology, high infiltration and low surface runoff. The Varatanapalli, Bargur River I, Mathur River II, Bargur River II, Kandili and Mathur River III miniwatersheds are classified as moderately suitable and Maharajagadai RF miniwatershed is classified into poorly suitable for groundwater prospective based on moderate to low infiltration, runoff and relief characteristic nature. 412

11 Acknowledgements The First author thanks Infosys Technologies Ltd., Bangalore, India for the permission and support rendered throughout this study. The Second author gratefully acknowledges the Vice Chancellor, Anna University, Chennai for the support provided. The Support and valuable inputs provided by Dr, Anbazhagan, Periyar University, Salem during the course of this work is gratefully acknowledged. 6. References 1. Biswas, S., Sudhakar, S., and Desai, V.R (1999), prioritization of subwatersheds based on Morphometric Analysis of Drainage Basin: A Remote Sensing and GIS Approach. Journal of the 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 Chow Ven T (1964), handbook of applied hydrology. McGraw Hill Inc, New York. 4. Clarke, J.I (1966), morphometry from Maps. Essays in Geomorphology. Elsevier Publ. Co., New York, pp Dornkamp, J.C. and King CAM (1971), numerical analyses in geomorphology, an introduction. St. Martins Press, New York, pp Gottschalk, L.C (1964), reservoir Sedimentation. In: V.T. Chow (ed), Handbook of Applied Hydrology. McGraw Hill Book Company, New York, Section 7 I. 7. GSI (1981), geological and mineralogical Map of Karnataka & Goa, Geological Survey of India. 8. Horton, R.E (1945), erosional Development of Streams and their Drainage Basins; Hydrophysical Approach to Quantitative Morphology. Geol. Soc. Am. Bull., 56, pp Horton, R. E (1932), drainage basin characteristics, Trans., Am. Geophys. Union, 13, 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 Miller, V.C (1953), a Quantitative Geomorphic Study of Drainage basin Characteristics in the Clinch Mountains area, Virginia and Tennessee, Proj. NR pp , Tech Rep 3, Columbia University, Department of geology, ONR, New York. 12. Nag, S.K. and Chakraborthy. S (2003), influence of rock types and structures in the development of Drainage Network in Hard Rock Area. J. Indian Soc. Remote Sensing, 31(1), pp

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