Adaptation of the Phosphorus Index to irrigated areas in the middle Ebro Basin. Las Filadas watershed case study (Huesca, Spain)

Abstract

In semi-arid irrigation areas, one of the most important surface water quality problems is nutrient pollution from agriculture through irrigation return flows, which can lead to their eutrophication. The element that most frequently limits the growth of aquatic vegetation is phosphorus (P) that may cause eutrophication above certain thresholds. Several management models for phosphorus diffuse pollution by agriculture are available currently, some of which resort to the use of indices. An index of phosphorus risk loss (PI) is a (usually) numerical value that weighs in a qualitative way the risk of water pollution by P associated to the farming practices and the soil and meteorological conditions in a zone. For that purpose, a PI must account for and integrate the processes involved in P availability and transport. In this work, a new PI (called IPreg) has been developed for the irrigated area within “Las Filadas” gully watershed (Huesca, Spain).