The study estimates geomorphological parameters and soil loss using the Universal Soil Loss Equation (USLE) and Geographical Information Systems (GIS) techniques for the Juni nadi watershed in Jammu Siwaliks with the idea of helping planners develop soil conservation strategies. Geomorphological characteristics of a river basin shape runoff processes and the occurrence of floods especially in the mountainous areas. In ungauged catchments with limited data, such as Juni nadi watershed, these parameters can be useful in understanding the hydrological characteristics. Reliable estimates of soil loss too can be useful in formulating watershed strategies to reduce soil loss to acceptable levels.
It is useful in determining the role of geomorphology on watershed runoff response and in identifying the parameters that are closely related to runoff. It looks at geomorphological parameters of the channel system like the linear aspects and areal aspects apart from determining the relief aspects of the watershed.
As per the study, about 62 % of the area of the watershed falls within the 0.15 % slope category, while slope is very high (> 50 %) in the upper reaches. Bifurcation ratio varies between 2 and 5.23, which shows the influence of geology on the drainage pattern. Drainage density of the watershed is 3.54 km/ sqkm and the stream frequency is 7.08/ sqkm, indicating high amount of runoff from the watershed due to steep slopes on upper reaches. The form factor of 0.22 confirms that the watershed has moderately high peak flows of shorter duration.
It also reveals that most of the catchment area falls under low (< 4.5 t/ha/year) and moderate (4.5 to 11.2 t/ha/year) soil erosion class. One third of the watershed comes under the high (11.2 to 25 t/ha/year) and very high (> 25 t/ha/year) category. Since the USLE model does not take into account the transportation and deposition of the detached soil particles (trap efficiency and delivery ratio) the actual sediment load at the outlet is likely to be less than the above estimate. Soil loss is found to be highest along the main river channel and on higher reaches of the watershed.
The geomorphological parameters estimated may be utilized for testing hydrological models to simulate hydrological response of the watershed.
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