| Abstrakt: |
Intensive irrigation makes the Imperial and Mexicali Valleys, located on the U.S./Mexico border, a thriving, year-around agricultural region. One by-product of the irrigated agriculture, however, is the nonpoint introduction of sediment, pesticides, and nutrients to the surface water. A parcel-scale erosion model is linked to drainage-scale agricultural information in a GIS and is used to quantitatively estimate sediment yield from a 13,000-hectare study area. Model results provide insight into the causes and patterns of sediment yielded to the drain system. Intensive row crops (e.g., sugar beets and onions) are identified as the major contributors to the sediment problem. Analysis shows that 25 percent of the parcels contribute 87 percent of the sediment to the drain system, and that the northern half of the study area is responsible for over 70 percent of all sediment generated. Several ways in which these patterns could be used to develop mitigation strategies are discussed. [ABSTRACT FROM AUTHOR] |
