Spatial scale and seasonal dependence of land use impacts on riverine water quality in the Huai River basin, China

Abstract

Land use pattern is an effective reflection of anthropic activities, which are primarily responsible for water quality deterioration. A detailed understanding of relationship between water quality and land use is critical for effective land use management to improve water quality. Linear mixed effects and multiple regression models were applied to water quality data collected from 2003 to 2010 from 36 stations in the Huai River basin together with topography and climate data, to characterize the land use impacts on water quality and their spatial scale and seasonal dependence. The results indicated that the influence of land use categories on specific water quality parameter was multiple and varied with spatial scales and seasons. Land use exhibited strongest association with dissolved oxygen (DO) and ammonia nitrogen (NH-N) concentrations at entire watershed scale and with total phosphorus (TP) and fluoride concentrations at finer scales. However, the spatial scale, at which land use exerted strongest influence on instream chemical oxygen demand (COD) and biochemical oxygen demand (BOD) levels, varied with seasons. In addition, land use composition was responsible for the seasonal pattern observed in contaminant concentrations. COD, NH-N, and fluoride generally peaked during dry seasons in highly urbanized regions and during rainy seasons in less urbanized regions. High proportion of agricultural and rural areas was associated with high nutrient contamination risk during spring. The results highlight the spatial scale and seasonal dependence of land use impacts on water quality and can provide scientific basis for scale-specific land management and seasonal contamination control.

Assessing Anthropogenic Impacts on Chemical and Biochemical Oxygen Demand in Different Spatial Scales with Bayesian Networks

“…Researchers have analyzed the impacts of different human activities on water quality, such as agricultural fertilization, loss of woodland and grassland, urbanization and contaminations from domestic and industrial wastewater [9,10]. Spatial variations of anthropogenic activities may cause a different distribution of land use across the whole river basins [11]. Although some previous studies only focused on a single spatial scale when analyzing the effects of human activities on water quality [12][13][14], some other research took the different spatial scales, from local scales to the whole catchment scale, into consideration [15][16][17].…”

Application of positive matrix factorization to identify potential sources of water quality deterioration of Huaihe River, China

“…Significant spatial variation is observed in precipitation which ranges from 1400 mm in the southern mountain region to less than 700 mm in the northern region near the Yellow River. In total, 51% annual runoff is stored by dams and sluices (Liu et al 2017). Both point and NPS pollution degrade surface water quality.…”

“…The elevated concentration of NH3-N in surface waters may be a consequence of irrigation tail water discharges due to favorable environmental condition in the region (Afed et al 2017). Agricultural land continuously impairs surface water quality throughout the year with strongest impacts in dry season (summer and autumn) due to lower dilution (Liu et al 2017). Industrial land use has positive association with COD.…”

“…NH 3 -N and COD loading is higher in rainless season due to lower dilution effect. NH 3 -N concentration is higher in spring which may be due to high agricultural activities in the region (Liu et al 2017). The study area is characterized by double cropping system, i.e., wheat and maize.…”

“…Furthermore, seasonal first flush of rainfall is the second potential cause of water quality degradation (Liu et al 2016). Late spring rainfall, after long dry season, drains fertilizers and pesticides to nearby watercourses which degrade surface water quality (Liu et al 2017).…”