Landscape ecological approach to the relationships of land use patterns in watersheds to water quality characteristics

It is widely accepted that strong ties exist between land uses and the water quality of adjacent aquatic systems within a watershed. Recently, studies of the relationships between land uses and water quality have also begun to consider the spatial configuration of land uses. Here we investigated the spatial configuration of land uses within watersheds in South Korea and examined how spatial patterns of urban, agricultural, and forest land uses measured at both landscape and class levels, related to water quality in adjacent reservoirs from landscape ecological perspective. The results indicate that water quality of reservoirs is closely associated with both the proportions of land use and the configurations of urban, agricultural, and forest areas. Water quality is more likely to be degraded when there is high interspersion of various land use types and when a large number of different land use types exist within a watershed. For urban land uses, high patch and edge densities, and urban land use as the largest patch, were also associated with water quality degradation, as were higher degrees of patch density and edge density for agricultural land uses. Water quality is likely better if forest patches are unfragmented, have a high value for the largest patch proportion, have complex patch shape, and are aggregated.