SEDIMENT AND NUTRIENT EXPORT MODELING IN A SUBWATERSHED OF KRISHNAGIRI RESERVOIR PROJECTS. SASITHARAN AND E. ARUNBABUAbstract The present study modeled the sediment and nutrient export from an agricultural catchment of middle Ponnaiyar subwatershed to the highly eutrophicated Krishnagiri reservoir located in the Krishnagiri district of Tamil Nadu. Soil Water Assessment Tool (SWAT) was used to quantify the nutrient loading from the catchment area. In addition to basic inputs such as DEM, Land use and soil, the management practices especially land preparation and nutrient supply is an essential input for nutrient simulation. Crop details, fertilizer application rates, irrigation frequency, tillage operation were obtained through Questionnaire survey, Key Informant Interview and Secondary data from Local Agricultural Agencies. SWAT model showed that the highest export of Total Nitrogen (TN) of 29 kg ha-1yr-1 and Total Phosphorous (TP) of 16.43 kg ha-1yr-1 was found from the fourth sub basin of middle Ponnaiyar subwatershed. The pasture land in the catchment area contributes higher sediment yield than agricultural lands. TN exports are higher (3.08 kg/ha/yr) from the croplands where more than two crops are cultivated and TP exports are higher (4.08 kg/ ha/yr) from row crops. |