Measuring the Impacts of Land Use on Water Quality Influenced by Non-Point Sources

The objective of this study is to (a) test the proposition that the variance of water quality from undefined sources is a function of land use within the watershed, and (b) examine the premise that the impact of land use near the stream is more important than that far away from the stream in affecting the water quality from non-point sources. Results obtained using this approach support both these hypotheses. Moreover, these tests suggest the importance of considering the means by which chemical elements are delivered to the streams. Nitrate-nitrogen and phosphorus can probably be intercepted by different means because of their varying delivery systems. Nitrate-nitrogen can be intercepted by removal of fast-growing floodplain crops and phosphorus by sediment barriers at sites outside the floodplain. Further evidences suggest that reservoir trap-efficiency is considerably important in improving the downstream water quality as the former entraps clay nanominerals (with adsorbed particulates of phosphorus) that are found to be responsible for the fate and transport of phosphorus. The methodology of analysis of stream loads is ordinary least square regression analysis. Stream loads of nitratenitrogen and total phosphorus have been studied as a function of land use.