Riparian Land Use and Management of Nonpoint Source Pollution in a Rural Watershed

摘要

Water quality degradation through increased non-point source pollution has become a widespread problem throughout the world. Nonpoint source pollution occurs because human activities such as agriculture, forest harvest, urbanization, have altered thestructure of the rural landscape and increased the quantity of substances like sediments, nitrogen, chlorine etc, loaded to the river system. There is increasing evidence that nitrate contamination of river waters occur in agricultural watersheds locatedin rural areas. In an effort to control and restore stream water quality, regulating agencies emphasize Best Management Practices and techniques that incorporate natural physical and biological processes that reduce, convert, or store pollutants on theland before they enter the surface water system. In rural watersheds, the riparian land use remains as a crucial link between the terrestrial catchments (uplands) and the stream environment. Their intermediate location gives these areas some of the characteristics of both uplands and lowlands. The riparian zone vegetation is composed of tree species that are tolerant to a range of moisture conditions including dry and saturated conditions. The chemical and biological processes that occur in riparian forest buffers tend to transform the nutrients and chemicals entering the riparian zone from upland sources into less harmful forms. So, it has been widely believed that these riparian buffer zones are effective in reducing the nutrient concentrations in water that pass through them (Jacobs et.al., (1985), Nakamura et.al, (2000), Kato et al, (2001)) Researchers around the globe, agree that riparian forest buffer strips function as important regulators in stream water quality, and so becomes important to determine the amount of reductions and the influence of land use characteristics around the riparian sites. In an era where the importance of interactions between agricultural operations and rural resource contributions are recognized, the methods and mechanisms of control or influence over stream nutrient concentrations must be understood. Therefore, this study was undertaken to determine the impact and effectiveness of riparian forest zone on reducing the nonpoint source pollution in a rural watershed.