The influence of land use patterns on water quality at multiple spatial scales in a river system

Abstract

The influence of land use patterns on water quality in a river system is scale‐dependent. In this study, a four‐order hierarchical arrangement method was used to select water sampling sites and to delineate sub‐basins in the Daliao River Basin, China. The 20 sub‐basins were classified into four spatial scales that represented four different stream orders. Pearson correlation analysis was used to quantify relationships between land use composition and the river's physical‐chemical variables for all samples collected. This analysis showed that the presence of forest cover was associated with higher water quality at the scale of the whole basin. The scale effects of land use patterns on water quality were then examined using stepwise multiple regression analysis that compared different land use types with water quality variables. The results from this analysis showed that urban areas, as opposed to forest areas, became the most significant contributors of water pollutants when scale effects were considered. The influence of urban land cover on water pollution was significantly higher at larger scales. The lack of a significant regression correlation for the forest land use type at smaller scales revealed that forest located upstream of the Daliao River Basin did not provide a buffer for improved water quality. Further analysis showed that this result could be because of disproportionate spatial distributions for forest and urban land use types. The topographic characteristics of sub‐basins, such as average slope (S) and size (A), were determined to be secondary explanatory variables that affected land use impacts on stream water quality. Areas with steep slopes were associated with increased water oxygenation, whereas areas with flatter slopes were associated with higher concentrations of pollutants. These results are significant because they can provide a better understanding of the appropriate spatial scale required for effective river basin management in the future. Copyright © 2013 John Wiley & Sons, Ltd.

Impacts of land use and population density on seasonal surface water quality using a modified geographically weighted regression

“…The positive and negative relationships between AG and TN, TP and NH 4 + -N in GWR analysis (Figs.4, 5 and 8) showed divergence from our OLS results (Table 2) and other studies using traditional global statistical methods (e.g., Seeboonruang, 2012;Wang et al, 2014;Wan et al, 2014;Chen and Lu, 2014). In these studies, AG had a strong positive effect on a b water pollution indicators because agricultural activities, such as fertilizer and pesticide application and livestock farming, are often the main non-point pollution source.…”

“…In addition, a higher percentage of impervious surfaces in urban areas prevents rainfall from infiltrating into soil resulting in transport of soluble and particulate forms of pollutants to nearby streams through surface runoff. These results are consistent with several previous studies examining pollutant inputs from urban areas (Walsh and Wepener, 2009;Peters, 2009;Tu, 2011;Liu et al, 2013;Mei et al, 2014;Wang et al, 2014).…”

Impact of land use changes on water quality in headwaters of the Three Gorges Reservoir

“…The average distance (D i,k ) from all grids with land use type i to the outlet (k) of a basin can quantitatively reflect distribution patterns of land use types relative to outlets (Wang et al 2014). The basic calculation of D i,k is:…”

Oferta de serviços ecossistêmicos hídricos diante da conversão de paisagens savânicas em campos antrópicos

“…Portanto, a escala espacial utilizada neste trabalho para a investigação da relação entre mudança no uso da terra e qualidade da água (WANG et al, 2014) pode ter contribuído para a ocorrência dessas divergências.…”

“…Esse resultado é provavelmente devido a maior declividade onde se localiza o campo antrópico nessa bacia -um dos principais fatores que interferem no processo de erosão (ZONTA et al,2012). Esse caso evidencia a importância da configuração resultante da conversão desses sistemas florestados em campo antrópicos (LEE et al, 2009), assim como o relevo da área convertida (WANG et al, 2014;YU et al, 2015).…”