Linking Land Use with Water Pollution in Coastal Watersheds of China

Abstract

Land-water relationship studies are important for watershed and coastal management. Changes in watershed-wide land use may exacerbate water pollution due to non-point source (NPS) and point-source (PS) pollutants, two major contaminants to the watershed-coast continuum. We take two largest coastal watersheds in Fujian Province, namely, Jiulong River watershed (JRW) and Minjiang River watershed (MRW), as the study site to examine the land use/cover and water pollution linkage, thereby suggesting land-water management implications. Land transformations have been accelerating across the JRW during the past 30 years. Urban watersheds were significantly more polluted than agricultural and natural watersheds. The spatial and temporal variations of water quality in the JRW are largely governed by the combination of natural factors (e.g. hydrology and biochemical processes) and anthropogenic inputs from industrial, agricultural, and urban activities. Climatic variability also affected the land use and water quality relationship and the performance of empirical regression models. Land use can affect river pollution, and such relationships vary spatially. Land use-water quality correlation is weakening under simultaneous point-source pollution. Furthermore, we developed three watershed modeling tools, namely, GIS-based empirical models, AnnAGNPS model, and SPARROW, to estimate non-point source nitrogen (N) and phosphorus (P) pollution, determine the sources of contaminants, and develop nutrient management strategies, respectively. Finally, we discuss the implications for water resource management.