| چکیده انگلیسی مقاله |
Watersheds are important for stabilizing ecosystems and micro climates. To conserve and maintain soil integrity in a watershed through strategic planning and applying best management practices, it becomes necessary to identify the degree of vulnerability of watersheds to soil erosion. There are various factors like land use, slope, morphology, topology, and rainfall which determine the vulnerability of watershed. Soil erosion vulnerability of a watershed can be determined quantitatively as well as qualitatively by using existing models. Sometimes, lack of data required for assessing vulnerability becomes a constraint to understand the status of soil erosion vulnerability. In such a scenario water quality can be an indicator of soil erosion in the upper reaches, and can therefore be used for rapid assessment of vulnerability of watershed to soil erosion. This paper provides an understanding of how changes in water quality can be used to determine the status of soil erosion vulnerability of watersheds. The study was conducted in a watershed which lies in the fragile ecosystem of lesser Himalayas. Based on availability of the water streams, ten sub watersheds were selected and were classified into low, medium, high and very high vulnerability class using Multi-Criteria Analysis, based on compound value using hydrology tool in ArcGIS10.3, with sixteen parameters belonging to morphology, land use and slope. 154 water samples were collected in three different seasons from outlet of each sub watershed and water quality parameters were estimated. Multinomial Logistic Regression was then performed to predict the shift of vulnerability status of watershed, taking very high vulnerability as the reference. The results showed that Electrical conductivity (EC), Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) are the main water quality parameters that can predict the transition of soil erosion vulnerability from low, medium and high to very high category. The results indicated that per unit change in TSS will lead to 43 percent chance of shifting vulnerability status of the sub watershed from low to very high. Also, 83 percent and 94 percent chance of shift was predicted from medium and high to very high vulnerability status respectively in sub watersheds. Similarly, the chances of shifting of the vulnerability to Very High from each of the other three by observing the water quality have been determined. The study highlights the importance of water quality in predicting the shift in soil vulnerability of watershed as an auxiliary group of variables. |
