Geo-Analyst , ISSN 2249-2909 July, 2016

MORPHOMETRIC ANALYSIS AND HYDROLOGICAL BEHAVIOUR OF BASIN, AND WEST ,

Rupen Mal * nd Prof. V.C. Jha **

Abstract

The analysis of drainage basin morphometryhas been undertaken to assess the hydrological behavior of the Brahmani river basin comprising eastern part of Chhotanagpur plateau. In this area, a large number of stream segments are originated from the Chhotanagpur plateau region and flow to the east ward and finally joined to the Dwarkariver in district. Rain water significantly provides to the evolution of drainage pattern in this basin area. Quantitative Morphometry plays a vital role for the analysis of hydrological behavior as well as processes. The morphometric analysis of this river basin was done by the geospatial technique. The analysis expresses that the entire study area is lithologically uniform and structurally permeable. As, the high drainage density of different sub watersheds indicate more surface runoff. Morphometric analysis indicates that the study area is more active for weathering due to very coarse to moderate drainage texture. The drainage pattern of all the watersheds is dendritic to sub dendritic in this basin. The high bifurcation ratios are highly controlled the structure on drainage pattern. The elongation and circulatory ratios showed that all the sub watersheds have elongated to circular shapes. Integrated analysis of morphometric parameters reveals that an important hydrological behavior of all the 12 sub watersheds which could be supposed.

Keywords: Morphometry, Hydrological Behavior, Drainage Density, Drainage Texture .

Introduction

The term Morphometry is defined as the measurement and mathematical analysis of the configuration of the earth surface, shape and dimension of its landforms (Agarwal, 1998; Obi Reddy et al. , 2002; Pakhmode et al. , 2003). The different quantitative methods have been developed to understand the behavioral characteristics of the drainage pattern of a basin (Leopold & Maddock 1953; Abrahams,1984). In the field of hydrology, drainage characteristics are the fundamental parameter for understanding of the hydrological processes operating at the watershed scale. In hydro-geomorphology, watershed is considered as the indispensable unit to study the

*Research Scholar, Department of Geography, VisvaBharati, Santiniketan, W.B., India and Junior Geographical Assistant, NATMO, Govt. of India

**Professor, Department of Geography, VisvaBharati, Santiniketan, W.B., India

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hydrological processes,erosional landscape. It is the fundamental units of fluvial landform and helps to find out the watershed geometric characteristics like, stream network, drainage pattern and drainage texture (Abrahams, 1984). Hydrologic as well as geomorphic processes are operating within the watershed and the morphometric analysis of the micro level watershed reveals the idea about the formation and development of land surface processes (Singh, 1992; Dar et al. , 2013). Different hydrological processes such as basin travel time, time to hydrograph peak and intensity of erosional processes occurring in the watershed scale which can be predicted the better accuracy from the morphometric evolution of a watershed. Morphometric analysis of watershed provides the very good information relating to soil, geology and geomorphology to understand the controlling factor of hydrological behavior (Romshoo et al. , 2012). There are found the practical application of quantitative morphometric analysis i.e. river basin evolution, soil characteristics, water and natural resources conservation and management. Morphometric analysis of watershed gives a quantitative description of drainage system and characterization of watershed (Strahler, 1964).Using the various conventional methods or techniques, the morphometric characteristics of river basins and sub basins in different part of the world has been carried out (Strahler,1964;Strahler, 1957). Now a day, the assessment of drainage basin Morphometry has becomemore accurate and precise due to the development of computer technology and geospatial techniques. While now a days, evolution of GIS techniques, morphometric parameters of drainage basins are evaluated through the easy and accuracy methods. The satellite data and GIS techniques gives the greater success to generate the data of spatial deviation and necessary hydrological condition for watershed management (Das & Mukherjee 2005; Vittala et al. , 2004; Nag, 1998). GIS is the powerful tools to manipulate and analysis of spatial data and provides the very good environment for morphometric analysis. In this present study, the morphometric characterization of 12 sub watersheds of Brahmani river basin was prepared in the GIS environment (Altaf et al. , 2013). Morphometric analysis of the Brahmani river basin lies in the fact that this river basin forms the irrigational and economic development of this region. As the Brahmani river is a non- perennial river and flow character is seasonal in nature. So, the contribution of rainfall largely helps to evaluate the drainage lines in this area. Therefore, the comparative study of different quantitative morphometric parameters of river basin will definitely help to understand the geomorphological impact on the spatio-temporal change of the hydrological function. Some important morphometric parameters such as bifurcation ratio and circularity ratio are the input parameters for the hydrograph analysis (Esper, 2008; Bhagwat et al. , 2011; Bhaskar et al. , 1997; Jain et al. , 2000) and also the evaluation of surface water potentiality of this region (Suresh et al. , 2004). It is said that, the study of morphometric analysis has greater impact for understanding the hydrological behavior of the study area it influences the socio-economic aspects of the Brahmani river basin.

Location and Geographical Background of the Study Area

Brahmani river, the main tributary of Dwarkariverspreads its network within the Jharkhand ( and ) and (Birbhum and ) state of Eastern India.The valley of this river starts from Chotonagpur plateau proper hilly terrain to the gangetic

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Geo-Analyst , ISSN 2249-2909 July, 201 6 plain of the Murshidabad district. The River basin extends from 24°09 ΄24 ΄΄ N. to 24°29 ΄31 ΄΄ N. latitudes and 87°17 ΄39 ΄΄ E. to 88°00 ΄58 ΄΄ E. longitudes covering an area of about 1163.69 km², extending from the Chhotanagpur plateau fringe in the West to moribund delta in the East. River Pagla which delimits the northern boundary of the region and delimits the southern boundary. The catchment area is bounded by the district boundary of Murshidabad in the East, Dumka in the West, Pakur in the North, and Birbhum in the South.Administratively, the study region comprises 14 CD Blocks namely, Jama, Ramgarh, Dumka, , , , Pakuria, Maheshpur(Jharkhand); RampurhatI,RampurhatII, I and Nalhati II, Khargram and Nabagram(West Bengal).There are 12 major sub watersheds among which 7 are in the left sides and 5 are in the right side of the main water course.Hydrologically the left side tributaries are much more active than the right side tributaries. The main source of water of river Brahmani is the rain. Sub-tropical monsoonal climate and deciduous forest characterize the region with weather extremit y and seasonal concentration of rainfall.

Fig. 1: Showing the location of the study area

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Materials Used

To demarcate the river basin and thereby to perform morphometric measurement, subsequent mapping and analysis Topographical maps of the Survey of India (SOI) [73P/7, 73P/8, 73P/11, 73P/12, 73P/15, and 73P/16and78D/4] at the scale 1:50,000 have been used. The Morphometric analyses have been undertaken by dividing the entire basin into several grids with 1 sq. km. grid area. ESRI Arc GIS, softwares have used for spatial mapping purpose.

Methods

Generation of drainage

The drainage line was generated from the survey of India topographical maps at1: 50000 scales in the GIS environment .The GIS software i.e. Arc GIS was used for generation of drainage which is more logical and perfect when it is compared to the manual process (Engelhard et al. , 2011 ).The Natural drainage lines present in SOI toposheets were digitized and used to manipulate from the SRTM DEM. For the actual determination of flow direction and flow accumulation DEM have beenused. The 12 sub watersheds boundaries were identified by the highest point where the two different drainage lines were drained opposite to each other. As a result, the watersheds boundaries were prepared (Figure 1) and the whole basin boundary was also prepared. Area of each sub watersheds wasfound out through the polygon preparation in Arc GIS software in the GIS environment. On the other hand, the length of the watershed was calculated by summing the length of the main stream channel and the distance from the top of the main channel to the watershed boundary. By summing the lengths of all stream segments in each sub watershed the total stream length was calculated.

Quantitative Morphometric measurement:

In this study, morphometric analysis of the different parameters, i.e. stream order,stream length, bifurcation ratio, relief ratio, drainage density, drainage intensity, drainage texture, drainage frequency,drainage texture, form factor, length of overland flow, constant channel maintenance, circulatory and elongation ratio,area, perimeter, and length of all the 12 sub-watersheds havebeen carried out using the standard mathematical formulagiven in the Table 1 (Strahler,1964;Strahler,1957;Suresh etal. ,2004;Horton,1945;Schumms,1956;Horton,1932;Miller,19 53;Faniran,1968). The values of various sub-basin characteristics required for calculating the morphometric parameters which are shown in the following table 1.

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Table 1: Showing the Methodology for Calculating the Morphometric Parameters

Sl. Morphometric Formulae/ Laws References No Parameters 1 Stream Order ( ) Hierarchical Ranking of streams (Strahler,1964) 2 Stream Length(Lu) Length of the stream (Horton,1945)

= /; Where, = mean stream length; =Total stream length of (Strahler,1964) 3 Mean Stream length(Lsm) order “ ”; = Total no. of stream segments of order “ ”

= / − 1; Where, = Stream length ratio; =The total

Stream Length Ratio ( ) streamlength of order “ ” − 1 =The total stream length of its next lower (Horton,1945) 4 order = / + 1; Where, = Bifurcation ratio; 5 Bifurcation Ratio ( ) = Total no. of stream segments of order “ ” (Schumms,1956) + 1 = Number of segments of the next higher order ℎ = /; Where, ℎ = Relief ratio; 6 Relief Ratio ( ℎ) H = Total relief (Relative relief) of the basin in Kilometer; = Basin (Schumms,1956) length = /; Where, = Drainage density; 7 Drainage Density ( d) = Total stream length of all orders; (Horton,1932) A = Area of the basin (km2) Df = /; Where, Df= Drainage frequency; 8 Drainage Frequency (Df) = Total no. of streams of all order (Horton,1932) = Area of the basin (km2) = /; Where, = Drainage texture; 9 Drainage Texture ( ) (Horton,1945) = Total no. of streams of all orders; = Perimeter (km) = /2; Where, = Form factor; = Area of the basin (km2); 2 = 10 Form Factor ( ) (Horton,1932) Square of basin length = 4 ∗∗/2;Where, = Circularity ratio; = “ ” value that is 3.14; A 11 Circularity Ratio ( ) (Miller,1953) = Area of the basin (km2); P = Perimeter (km) = (2/ )∗(/);Where, Re = Elongation ratio 12 Elongation Ratio ( ) (Schumms,1956) = Area of the basin (km2); = “ ” value that is 3.14; = Basin length Length of overland flow 13 = 1/ D ∗2;Where, = Length of overland flow; D = Drainage density (Horton,1945) () Constant Channel 14 = 1/ ; Where, D = Drainage density (Schumms,1956) Maintenance(C) = 1/ ; Where, N1 = Total number of streams in 1st order; P = 15 Texture Ratio ( ) (Schumms,1956) Perimeter of basin 16 Drainage Intensity ( ) = Df/ ; Where, Df= Drainage frequency; = Drainage density (Faniran,1968)

Source: Compiled by the author

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Results and Discussion:

Stream order (U)

Stream order is the successive assimilation of streams within a drainage basin .Stream order is designated as the first step in drainage basin analysis. It is based on the hierarchical ranking of streams in the basin (Strahler, 1964). According to references (Strahler, 1964)the smallest fingertips have no tributaries are designated as first order stream. The second order streams having only first order steams as tributaries. Similarly, third order stream have first and second order streams as tributaries and so on.

The highest stream order is sixth which is found only one sub watersheds i.e. WS1 among 12 sub watersheds and the lowest stream order is fourth and is found by WS3, WS4,WS5,WS7,WS8,WS9, WS10,WS11and WS12 respectively. The fifth order stream is found in WS2 and WS6.Table no. 3 and Figure 1 also indicates that the 12 sub watersheds draining into Brahmani River are contributing surface runoff (water) and sediment loads differentially due to the variations in their physical characteristics. There are only 7 sub watersheds in the western side of the river among which four watersheds have stream order 4 and only two watersheds have stream order 5 and only one watershed have stream order 6. In the eastern side of the river, there are 5 sub watersheds out of which five watersheds have stream order 4. Drainage maps of all the 12 sub watersheds are shown below [Figures 4(a), 4(b), and 4(c)].

The higher stream order is associated with greater discharge, and higher velocity (Costa, 1987).Western side of the Brahmani River clearly contributes more to discharge and since higher velocity which enhances the erosion rates; so, this side also contributes higher sediment loads into river.

According to Horton’s law of stream numbers the total number of stream segments decrease with increasing stream order. Any type of deviation indicates that the landform is expressed with high relief and moderately steep slopes, underlain by varying lithology and probable uplift across the basin (Singh & Singh 1997).

In practice, when logarithms of the number of streams of a given order, are plotted against the order, the points lie on a straight line ((Horton, 1945 ). Similar geometric relationship was also found to operate between stream order and stream numbers in all sub watersheds of this study area. It indicates that the whole area has uniform underlying lithology, and geologically, there has been no probable uplift in the basin (Figure 2).

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2(a) Stream Order Subwatershed Boundary

First Order Fourth Order Second Order Fifth Order Third Order Sixth Order

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2(a) Stream Order

Subwatershed Boundary First Order Fourth Order Second Order Fifth Order Third Order Sixth Order

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Subwatershed Boundary 2(a) Stream Order First Order Fourth Order Second Order Fifth Order Third Order Sixth Order

Figure 2: (a) Showing Stream ordering maps of subwatersheds, WS1–WS4, (b) Showing Stream ordering maps of sub watersheds, WS5–WS8, (c) Showing Stream ordering maps of WS9-WS12 of Brahmani river basin.

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Stream Length (Lu)/Mean Stream Length (Lsm)

The numbers of stream segments of various orders in different sub-watersheds were counted and measured their lengths (Table 3) with the help of software (Arc GIS). Table 3 and 4 shows that the total length of stream segments are the maximum in case of first Order streams. Normally, the total length of the stream segments decrease when the stream order increases in all the sub watersheds. Therefore, the area is involved with uniform lithology and there is no probable basin upliftment. This observation indicates that the study area depends only on thedrainage characteristics for water runoff. There is more number of watersheds in the Western side of the Brahmani River. So, the total length of stream segments of all orders is greater than the eastern side of the river. Therefore, the longer travel times (Luo&Harlin, 2003) makes this western side hydrologically more active.

Moreover, Table 4 shows that the mean stream length (Lsm) in these subs watersheds range from a minimum of 0.66 km for stream order 4 of WS4 to a maximum of 1.05 km for the order 5 of WS6. According to the Horton’s law of stream lengths, Lsm of any given order is greater than that of lower order. This geometric relationship can be seen in Figure 3 .A comparative analysis of Lsm and stream length ratio RL of all the sub watersheds is shown in Table 4.

Drainage Frequency (Df)

Drainage frequency or Stream frequency is the measure of the total number of streams per unit area. In table 5 shows that the maximum drainage frequency is found in sub watershed WS4 (3.46/ km²) and also followed by WS5 (3.29/km²), WS3(2.72/km²), WS10 (2.65/km²), WS12 (2.46/km²), WS 11(2.41/km²),WS2 (2.10/²), WS8 (1.97/km²), WS7 (1.77/km²), WS1 (1.66/km²), WS6 (1.64/km²) and WS9 (1.63/km²). Drainage frequency has been very much related to the infiltration capacity, permeability and the relief of watersheds ( Montgomery & Dietrich 1989). In Brahmani river basin the values of drainage frequency are observed and also indicated that the WS5 is having rocky terrain and very low infiltration capacity out of all the 12 sub watersheds. Therefore, it is said that Drainage frequency decreases when the stream number increases. Drainage frequency of WS9 expresses that this sub watershed is generally covered with good number of vegetation and has also very good infiltration capacity. Analysis of the results of drainage frequency reflects the early peak discharge for subwatersheds in order of their decreasing stream frequency relating to the floods in monsoon season because of low runoff rates due to low number of streams.

Bifurcation Ratio (Rb) and Mean Bifurcation Ratio (Rbm)

Bifurcation ratio is the ratio between the number of streams of a given order and the number of streams of the next higher order which is expressed as the Rb. The mean bifurcation ratio (Rbm) is the average Bifurcation ratio of all stream orders. In the following table 5 shows that the mean bifurcation ratio (Rbm) of 12 sub watersheds are 3.68, 3.61, 4.21, 4.29, 3.59, 4.18, 4.81, 3.44, 3.71, 3.4, 4.13 and 4.14 for the WS1 to WS12. Due to the possibility of variation in watersheds geometry and lithology so that the mean bifurcation ratio does not remain constant from the one to the next higher order, but it tends to be the constant throughout the series. Analysis of results

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Geo-Analyst , ISSN 2249-2909 July, 2016 shows that the high Rbm indicates early hydrograph peak with a flooding situation during the period of monsoon. So, in the basin Rbm controls or dominates the powerful geology and also shows a small variation for different regions on different environments. Higher Rbm value means structurally more disturbed watersheds with a prominent variation of drainage pattern. The maximum Rbm value is found in WS7 i.e. 4.81 and shows that the early hydrograph peak and also indicates the strong structural control on the drainage development forthis watershed. On the other hand, the minimum Rbmvalue is found in the WS10 i.e. 3.4 which indicates late hydrograph peak in this basin.

Relief Ratio (Rh)

Relief ratio is the measurementof the overall steepness of a drainage basin and important indicator of the intensity of erosion processes which operating onthe basin slopes (Dodov&Foufoula- Georgiou 2005). Generally relief ratio value increases with decreasingdrainage area and size of a drainage basin (Gottschalk, 1964). Table number 7 shows that the relief ratio ranges from lower value i.e. 0.37 in WS2 to higher value 4.44 in WS5. The higher value reveals an intensity of erosion processes which are taking place in this watershed. As a result, WS5 is the more erosional and Ws2 is the least erosional watersheds among all 12 sub watersheds. Relief ratio is considered as the erosion intensity analysis.

Drainage Density (Dd)

Drainage density is a ratio between the total length of all the stream segments and total area of the given area. Generally, the factors of drainage density affects the stream lengths, resistance to weathering, permeability of rock creation, vegetation,climate, and so on. Lower the Dd value in regions which is lying under the highly resistant permeable material with more vegetative cover and low relief. High drainage density is observed in theregions of weak and impermeable subsurface material and low vegetation and higher relief. Table 5 shows that WS9, WS1, WS2, WS6, WS7, WS3, WS8, WS10 and WS11 have low of drainage density i.e. < 2.0 km/km². Only WS12 have moderate value of Dd (2.0- 2.5 km/km²). Sub watersheds WS5 and WS4 have high Dd value (above 2.5 km/km²). Under lying the low and moderate Dd values watersheds express that they are composed of permeable subsurface material,good vegetation cover, and low relief which affects in moreinfiltration capacity and comparably are good sites for groundwater recharge as compared to high values watersheds( Luo, 2000; Harlin&Wijeyawickrema, 1985).On the basis of Dd value, WS9 will have the longest basin lag time, while WS4 will indicates the shortest lag time.

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Table 2 : Showing some important Basin characteristics of Sub watersheds

Minimum Longest Sub Maximum Relative Basin Area Basin length Perimeter Height Flow path watersheds Height (Km) Relief (Km²) (Km) (Km) (Km) (Km) SW1 0.38 0.04 0.34 254.60 43.47 126.18 69.26 SW2 0.16 0.10 0.06 86.24 16.21 43.32 20.22 SW3 0.14 0.06 0.08 34.16 10.60 28.39 12.18 SW4 0.48 0.16 0.32 26.30 9.80 25.89 3.69 SW5 0.50 0.16 0.34 18.22 7.66 20.52 8.84 SW6 0.44 0.10 0.34 109.90 25.13 72.87 32.44 SW7 0.32 0.10 0.22 59.26 19.17 48.70 25.27 SW8 0.36 0.14 0.22 26.39 9.56 24.44 9.08 SW9 0.22 0.12 0.10 39.21 8.70 26.41 11.25 SW10 0.28 0.10 0.18 17.21 7.20 19.89 8.44 SW11 0.32 0.08 0.24 32.36 7.77 28.21 12.92 SW12 0.24 0.06 0.18 32.93 11.51 29.07 14.91

Table 3 :Showing Stream Order, Stream Number and Stream Length (Km) of Sub watersheds

Stream Stream Number Stream Length (Km) Sub Order watersheds I II III IV V VI I II III IV V VI WS1 6 322 73 19 6 1 1 193.53 85.20 37.36 15.48 41.92 24.41 WS2 5 140 30 8 2 1 - 73.09 30.21 23.21 12.97 5.73 - WS3 4 73 15 4 1 - - 41.11 9.50 6.31 4.72 - - WS4 4 73 14 3 1 - - 45.83 10.19 12.07 5.57 - - WS5 4 45 11 3 1 - - 26.30 10.59 2.48 6.69 - - WS6 5 142 30 6 1 1 - 111.54 37.65 15.43 4.97 20.69 - WS7 4 89 12 3 1 - - 59.02 21.37 14.92 11.03 - - WS8 4 39 9 3 1 - - 28.49 9.61 8.48 2.69 - - WS9 4 49 11 3 1 - - 28.51 19.36 5.01 6.69 - - WS10 4 32 10 2 1 - - 19.92 7.03 5.40 1.63 - - WS11 4 63 11 3 1 - - 37.87 10.98 8.88 6.73 - - WS12 4 65 12 3 1 - - 36.28 15.04 12.41 2.13 - -

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Drainage Texture (Rt)

Drainage texture is a ratio between the total number of stream segments of all the stream order in a basin and basin perimeter. It is largely influenced by the infiltration capacity ( Horton, 1945), lithology and relief aspect of the basin. According to Smith (1950) there are five categories of drainage texture i.e. very coarse (<2), coarse (2–4), moderate (4–6), fine (6–8), and very fine (>8) (Smith, 1950). According to this categorization, WS1, WS3, WS4, WS5, WS6, WS7, WS8, WS9, WS10, WS11 and WS12 have coarse drainage texture, and only one sub watershed i.e. WS2 has moderate drainage texture those are shown in the table no. 6. Hydrologically coarse drainage texture watersheds have large basin lag time periods ( EsperAngillieri, 2008) followed by moderate, fine, and very fine texture categories. It indicates that WS8 (Rt = 2.12) shows longer duration to peak flow and WS2 (Rt = 4.18) shows the shortest flow.

Table 4 : Showing the Mean stream length and Stream length Ratios of sub watersheds

Mean Stream Length(km) Stream Length Ratio Sub watersheds I II III IV V VI II/I III/II IV/III V/IV VI/V WS1 0.60 1.17 1.97 2.58 41.92 24.41 1.94 1.69 1.31 16.25 0.58 WS2 0.52 1.00 2.90 6.49 5.73 - 1.93 2.88 2.24 0.88 - WS3 0.56 0.63 1.58 4.72 - - 1.12 2.49 2.99 - - WS4 0.63 0.73 4.02 5.57 - - 1.16 5.53 1.39 - - WS5 0.58 0.96 0.83 6.69 - - 1.65 0.86 8.09 - - WS6 0.79 1.26 2.57 4.97 - - 1.60 2.05 1.93 4.16 - WS7 0.66 1.78 4.97 11.03 - - 2.69 2.79 2.22 - - WS8 0.73 1.07 2.83 2.69 - - 1.46 2.65 0.95 - - WS9 0.58 1.76 1.67 6.69 - - 3.02 0.95 4.00 - - WS10 0.62 0.70 2.70 1.63 - - 1.13 3.84 0.60 - - WS11 0.60 0.99 2.96 6.73 - - 1.66 2.97 2.27 - - WS12 0.56 1.25 4.14 2.13 - - 2.25 3.30 0.52 - -

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Table 5 : Showing Bifurcation Ratios, Drainage Density, Drainage Frequency and Drainage Intensity of the sub watersheds

Sub Bifurcation Ratio Drainage Drainage Drainage watersheds I/ II II/III III/IV IV/V V/ Density frequency Intensity VI WS1 4.41 3.84 3.17 6 1 1.56 1.66 0.10 WS2 4.67 3.75 4 2 - 1.68 2.09 0.41 WS3 4.87 3.75 4 - - 1.80 2.72 0.92 WS4 5.21 4.67 3 - - 2.80 3.46 0.66 WS5 4.09 3.67 3 - - 2.53 3.29 0.76 WS6 4.73 5 6 1 - 1.73 1.64 -0.09 WS7 7.42 4 3 - - 1.79 1.77 -0.02 WS8 4.33 3 3 - - 1.87 1.97 0.1 WS9 4.45 3.67 3 - - 1.52 1.63 0.11 WS10 3.2 5 2 - - 1.97 2.62 0.65 WS11 5.73 3.67 3 - - 1.99 2.41 0.42 WS12 5.42 4 3 - - 2.00 2.46 0.46

Table 6: Showing important morphometric parameters of the sub watersheds

Sub Relief Texture Elongati Circularity Form Length of Drainage Constant watersh Ratio ratio on ratio ratio Factor Overland Texture Channel eds Flow Maintenance

SW1 0.78 2.55 0.41 0.20 0.13 0.32 3.34 0.64 SW2 0.37 3.23 0.65 0.58 0.33 0.30 4.18 0.59 SW3 0.76 2.57 0.62 0.53 0.30 0.28 3.28 0.55 SW4 3.27 2.82 0.59 0.49 0.27 0.18 3.51 0.36 SW5 4.44 2.19 0.63 0.54 0.31 0.20 2.92 0.40 SW6 1.35 1.95 0.47 0.26 0.17 0.29 2.47 0.58 SW7 1.15 1.83 0.51 0.31 0.16 0.28 2.16 0.56 SW8 2.30 1.60 0.61 0.55 0.29 0.27 2.13 0.54 SW9 1.15 1.86 0.81 0.71 0.52 0.33 2.42 0.66 SW10 2.50 1.61 0.65 0.55 0.33 0.25 2.26 0.51 SW11 3.09 2.23 0.82 0.51 0.53 0.25 2.77 0.50 SW12 1.56 2.24 0.56 0.49 0.25 0.25 2.79 0.50

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Form Factor (Rf)

Form factor is the numerical index (Horton, 1932) which is used to represent different basin shapes. The value of form factor ranges between 0.1-0.8. Small value of form factor, the basin shape will be more elongated. The high value of form factor (0.8) indicates high peak flows of shorter duration and elongated drainage basin with low value of form factors have lower peak flow of longer duration ( Youssef et al. , 2011; Howard, 1990;Kochel, 1988). Analysis of the results, WS1, WS6 and WS7 shows the lower form factor which indicates the elongated shape of basins and flat hydrograph peak for longer duration. Elongated shape basins are easily managed the flood flow than the circular shape basins. Sub watersheds i.e. WS12, WS4, WS8, WS3, WS WS2 and WS10 have slightly circular shape of the basin and also suggested by moderately higher form factor (Rf). WS9 and WS11 have the higher form factor value which indicates the circular to rectangular shape basins. Therefore, Watershed morphology has greater impact on thewatershed hydrology ( Tucker & Bras 1998) .

Elongation Ratio (Re)

According to Schumm’s 1956, elongation ratio (Re) is the ratio of diameter of a circle of the same area and the basin to the maximum basin length. The value of Re varies from 0 to 1 that reveals the elongation shape to the circular shape of the basin. Thus higher the value of elongation ratio is more circular shape of the basin and vice-versa. There are different categories of elongation ratio i.e. < 0.7 (Elongated shape), 0.7 - 0.8 (less elongated), 0.8 – 0.9(oval shape) and > 0.9 (circular shape). The value of elongation ratio of different subwatersheds of Brahmani river basin are varies from 0.41 to 0.82 which shows in the table 7. Generally, the value of elongation ratio is associated with climate, geology, low and high relief of the basins. The value of elongation ratio (Re) for the sub watersheds WS1, WS7,WS6, WS12, WS4, WS8, WS3, WS5, WS25 and WS10 respectively is less than 0.70 which indicates that sub watersheds are elongated with high relief and steep slope. Only two watersheds such as WS9 and WS11 have higher the value of elongation ratio which indicates that the basin shape is oval shape in nature. It is observed that the WS1 will show delay time to peak flow and WS11 will show the shorter time to peak flow in the basin.

Circulatory Ratio (Rc)

The circularity ratio is a similar measurement technique of basin shape as like elongation ratio. According to Miller (1953), (Miller, 1953) the circularity ratio is defined as the ratio of the basin area to the area of the circle having same circumference as like the basin perimeter. The value of circularity ratio varies from 0 to 1 which indicates line to circle. The important basin characteristics such as stream length, drainage frequency, geological structures, climate, land use and land cover area, relief and slope of the basin etc. are largely influenced the circulatory ratio of the basins. So, it is an important technique to know the shape of the basin. In this study, circulatory ratio for WS1, WS6, WS7, WS4 and WS12 are in the range from 0.20 to 0.49 that indicating the area is characterized by elongated basin, high relief and permeable surface resulting in greater basin lag times. On the other hand, sub watersheds such as WS11, WS3, WS5, WS8, WS10, WS2

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Geo-Analyst , ISSN 2249-2909 July, 2016 and WS9 respectively have lower value of Rc (0.51 to 0.71) indicating circular basin shape, low relief and impermeable surface relating to the lower basin lag times. Therefore,Rf, Re and Rcsignificantly influence the hydrological characteristics of the watersheds and the arrangement of stream segments are influenced the size and shape of the flood peaks ( Ward & Robinson, 2000).

Length of Overland Flow (Lg)

Actually, the length of overland is used to express the length of flow of water over the surface before it going to the specific stream channels. It is an important independent variables which affecting both the hydrographical and hydrological development of drainage basins ( Horton, 1932). The values of length of overland flow of different sub watersheds shows in the table 7 i.e. 0.32, 0.30, 0.28, 0.18, 0.20, 0.29, 0.28, 0.27, 0.33, 0.25, 0.25 and 0.25 respectively. The length of overland flow for sub watersheds WS4 indicates steep slopes and shorter flow paths, while as LgforWS1, WS2, WS3, WS5, WS6, WS7, WS8, WS9, WS10, WS11 and WS12 indicate gentle slopes and longer flow paths. As a result, the length of overland flow has a significant relationship between the drainage density and constant channel maintenance.

Constant of Channel Maintenance(C)

In thisstudy, the constant of channel maintenance(C) varies from 0.36 to 0.64 for the watershed WS4 and WS9 which is shown in Table 6. There are reciprocal relationship between the drainage density (Dd) and the constant of channel maintenance and highly signifies that how much drainage area is required to maintain a unit length of channel.Lower values of C of WS4 indicates that this watershed is associated withvery low-resistance of soils, sparse vegetation cover area and mountainous terrain. On the other hand, the watershed WS9 is associated with high resistance of soils, dense vegetation and comparably plain land (Shulits, 1968).Higher the values of constant channel maintenance, there will be lower value of drainage density. As a result, higher value of constant channel Maintenance expresses strong control of lithology withhigh permeability. So, the alluvial plain area and piedmont zone shows the highest value, whereas the permeability is also high.

Conclusion

From the integrated analysis of Morphometry and hydrological behavior of the 12subwatersheds, it is concluded that the study area has overall uniform characteristics of lithology is same except the hilly area of the river basin in the western part, which helps to understand hydrological responses in the function of geomorphology, topography and existing vegetation condition. The spatial variation or deviation of analyzed the morphometric parameters in the study area is very much significant. As the watershed hydrology changes due to the spatial variation morphometric parameters, then the sub watersheds will reveals the different hydrological behavior. The results indicated that the comparative study of sub watersheds WS1, WS3, WS4, WS5. WS6 and WS7 shall contribute the stream runoff in the catchment area and sub watersheds WS8, WS9, WS10, WS11 and WS12 shall contribute very least due to the cumulative and integrated effect of morphometric parameters which significantly influence the hydrological behavior have been discussed in the above. Due to the close relationship between the morphometric parameters and

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