Spatial and Seasonal Dynamics of Water Environmental Capacity in Mountainous Rivers of the Southeastern Coast, China

Abstract

The south-east littoral is one of the most populous and developed regions in China suffering from serious water pollution problems, and the Xian-Jiang Basin in the mid of this region is among the most polluted watersheds. Critical information is needed but lacking for improved pollution control and water quality assessment, among which water environmental capacity (WEC) is the most important variable but is difficult to calculate. In this study, a one-dimensional water quality model combined with a matrix calculation algorithm was first developed and calibrated with in-situ observations in the Xian-Jiang basin. Then, the model was applied to analyze the spatial and temporal patterns of WEC of the entire basin. The results indicated that, in 2015, the total pollutant discharges into the river reached 6719.68 t/yr, 488.12 t/yr, and 128.57 t/yr for COD, NH3-N and TP, respectively. The spatial pattern suggested a strong correlation between these water contaminants and industrial enterprises, residential areas, and land-use types in the basin. Furthermore, it was noticed that there was a significant seasonal pattern in WEC that the dry season pollution is much greater than that in the plum season, while that in the typhoon season appears to be the weakest among all seasons. The WEC differed significantly among the 24 sub-basins during the dry season but varied to a smaller extent in other seasons, suggesting differential complex spatial-temporal dependency of the WEC.

A New Water Environmental Load and Allocation Modeling Framework at the Medium–Large Basin Scale

“…Eventually, the pollution loads that need to be reduced are 340.16, 25.11, and 11.41 tons for COD, NH 3 -N, and TP, respectively, in order to meet the stated water quality targets by year 2020. Detailed descriptions of the simulation process and model validation are available in Liu et al [19], and are not presented here for the sake of brevity.…”

“…A notable drawback of existing WLA, when applied at town or village scales in China, is its inability to practically identify individual polluters, the terminal implementers of WLA ( Figure 1). This is because the current WLA is pollutant-specific, without specific targeted sources of pollutions that can, in fact, come from many sources such as domestic sewage, agricultural non-point sources (NPS), and large-scale livestock breeding farms [19]. This ambiguity creates unfair and unpractical WLA policies, leading to ineffective practices.…”

Calculation of water environmental capacity of large shallow lakes – a case study of Taihu Lake

“…Large shallow lakes, especially those located in highly developed areas, provide multifunctional services for industry, agriculture, navigation, and recreation (Liu et al, 2018a(Liu et al, , 2018b. However, due to the continuous development of industrial and agricultural production and the growth of population along the lake area, the increasing amount of pollutants and the deteriorating lake water environment are causing a variety of water environmental problems.…”

Dynamic simulation of river water environmental capacity based on the subsection summation model

“…For WEC calculation modeling, Zhou, Guo, Cheng, Song, and Cao (1999) proposed sectionbeginning control, section-end control, and section-end control under a one-dimensional steady-state condition, which was applied to the Shaanxi reach of the Wei River. Liu, Jiang, Jing, and Qi (2018) developed a one-dimensional water quality model combined with a matrix calculation algorithm and applied this model to analyze the spatial and temporal WEC patterns of the entire basin. The spatial pattern suggested a strong correlation between water contaminants and industrial enterprises, residential areas, and land-use types in the basin.…”