Modelling Of Nutrient Losses Prediction From An Agriculture Watershed

摘要

In the present investigation validation of GIS linked physically based continuous time simulation hydrological model AVSWA2000 was carried out for nutrient (NO_3-N, organic N, soluble P, and organic P) losses prediction from an agricultural watershed of Eastern India. Digital data of IRS-1D LISS-Ⅲ was used for landuse/landcover classification of the study watershed. The runoff and sediment samples collected at the outlet of the watershed were analyzed for determination of nutrients loading. Model test and validation were performed sequentially for the sampled events in the monsoon season (June-September) of 2000 and 2001 respectively, for nutrients loss simulation. The observed and simulated mean of NO_3-N, organic N, soluble P and organic P were not significantly different at 95 % level of confidence since statistically the values of t-calculated were found to be less than the values of t-critical. The values of % deviation (D_v) were found to be -11.45, 14.16, -16.36, 7.83 (in 2000) and -17.06, -11.70, 12.12, 16.39 (in 2001) respectively for NO_3-N, organic N, soluble P and organic P. These results indicated that the model was predicting nutrient losses satisfactorily. The values of coefficient of determination (R~2 ) of 0.82, 0.84, 0.81, 0.82 (in 2000) and 0.830, 0.82, 0.81, 0.91 (in 2001) respectively for NO_3-N, organic N, soluble P, and organic P also indicated close agreement between the observed and simulated values of nutrient losses. Thus, AVSWAT2000 accurately simulated nutrient losses from the study watershed. The simulation results provides a basis for further scenario evaluation and eventually for recommendation of improved management practices for this watershed and other watersheds of similar hydrological conditions.