Use of a watershed model in the development of a River Basin Management Plan in a catchment with limited data

The estimation of existing nutrients load in a river is often challenging due to scarcity of measured data. In this case the use of a computer model is really helpful to assess the water quantity and nutrient balance of a water body, particularly in watershed affected by water pollution. The study watershed is the Candelaro River basin located in Italy, in a Mediterranean environment, that shows the typical hydrologic behavior of an intermittent river. The intensive agricultural activity is the main human pressure in the area. The flow gage measures are not available for a long time serie. The water quality monitoring activities carried out in order to classify the water quality of Candelaro River, in view of the development of a River Basin Management Plan, started on 2000 with monthly samples. The results of these activities, conducted only during the normal flow, showed that the water body often exceeds the limits of ammonia and P tot suitable for aquatic life. In order to achieve the objective of "good" status required by the Water Framework Directive (EU WFD 2000/60) different measures has been suggested to be adopted by the River Basin Authority in the "Regional Water Protection Plan". The different nutrient loads sources and the effectiveness of suggested measures included the application of BMPs in the agricultural area, have not been evaluated in the above mentioned Plan. In this study the SWAT model (Soil and Water Asessment Tool) has been applied to evaluate the contribution of different sources to the actual water quality of Candelaro River during the different hydrologic conditions. The effectiveness of different BMPs adoption in the agricultural areas has been assesed after the simulation of different scenarios.