Abstract: Spatial variation of water quality factors, including TN, TP, NH₄⁺-N, COD_cr, pH, DO and TDS, were analyzed by using GIS technique and geo-statistics method based on water sampling data collected in the Puhe River Basin from August to September 2012. Responses of water quality to land use changes were investigated. Results showed that the spatial distributions of NH₄⁺-N, DO and TDS were highly variable, and significantly affected by structural factorsincluding climate, topography, and hydrology. TP, COD_cr and pH showed weak spatial variations, and were significantly affected by random factors such as human activity. TN showed a weak spatial variation and was jointly affected by structural and random factors. TN and NH₄⁺-N were negatively related to the proportion of forest lands and positively related to the proportions of agricultural lands and construction lands. Moreover, pH and DO were negatively related to the proportions of water area and unused land. Our results indicated that forest, agricultural lands and construction lands were the dominant factors driving the spatial heterogeneity of TN and NH₄⁺-N, and that water area and unused land were the dominant driving factor for the spatial variation of pH and DO. Results from this study provide support for environment management of river basin.

Key words: sowing date, accumulation, remobilization, fruiting efficiency, nitrogen, winter wheat