Basin characteristics such as land use/land cover, slope, and soil attributes
affect water quality by regulating sediment and chemical concentration. Among
these characteristics, land use/land cover can be manipulated to gain improvements
in water quality. These land use/land cover types can serve as nutrient detention
media or as nutrient transformers as dissolved or suspended nutrients move towards
the stream. This study examines a methodology to determine nitrate pollution
'contributing zones' within a given basin based on basin characteristics. In
this process, land use/land cover types were classified and basins and 'contributing
zones' were delineated using geographic information system (GIS) and remote
sensing (RS) analysis tools. A 'land use/land cover-nutrient-linkage-model'
was developed which suggests that forests act as a sink, and as the proportion
of forest inside a contributing zone increases (or agricultural land decreases),
nitrate levels downstream will decrease. In the model, the residential/urban/built-up
areas have been identified as strong contributors of nitrate. Other contributors
were orchards; and row crops and other agricultural activities.