The Yongding River is the mother river of Beijing. However, due to the environmental pollution caused by the economic development, the water and coastal environment of this river has suffered from great destruction. The ecological restoration of the Yongding River is imperative. In this paper, we analysed seven basic water quality indicators in Yongding River based on Information Entropy and found that the main factors for affecting water quality were ammonia and CODMn. Then the basic water quality indicators were predicted, based on Grey System GM(1,1) model and we concluded that turbidity and conductivity would grow fastest in the next 20 years. Finally, we made some reasonable ideas and methods in Yongding River ecological restoration.

Based on the migration and transformation features of pollution sources in wide and shallow rivers, several monitoring points of water quality were set in the downstream to obtain a series of monitoring information. The changes of source intensity were, therefore, determined to present the problems in the inversion of instantaneous pollution sources during sudden pollution accidents. The research employs a differential evolution (DE) algorithm to inverse the location and number of emissions of pollutants discharged. The results show that the DE algorithm can accurately identify the sizes and locations of pollution sources and provide technical support for the identification of pollution sources. The research explored the impact of monitoring schemes on the accuracy of inversion results. It is of technical significance for manipulating and optimizing the emergency monitoring plans.

The subject in this paper is the surface water of Yuecheng Reservoir in Handan. On the premise of analysing variation characteristics of sulphate of Yuecheng Reservoir, we recognized reasons of increased sulphate concentration value resulting in water pollution. It drew conclusions that sulphate concentration in Yuecheng Reservoir varied significantly during winter and reached maximum. At the same time, there was a significant correlation between sulphate concentration of atmospheric precipitation in urban areas and sulphate concentration of Yuecheng Reservoir, which was because that the sulphate of atmospheric precipitation reached to the reservoir by surface runoff, having a certain degree of influence on the sulphate concentration of Yuecheng Reservoir.

Dissolved oxygen (DO), NH4+-N, total phosphorus (TP), CODMn and BOD5 in water in the Hechuan segment of Fujing River were monitored to assess water pollution in the river scientifically. Water pollution indexes were analysed and their pollution load-sharing ratios were calculated by using single pollution index method and Nemerow comprehensive pollution index method, respectively. Results show that the water quality in 25% of the monitored sections can be considered clean and the water quality of 75% of the sections can be considered slightly polluted in two water functional zones in the Hechuan segment of Fujiang River with water quality control targets of Level III and Level IV, respectively. Water quality declines from upstream to downstream. DO does not exceed standards in all the sections. NH4+-N significantly contributes to water pollution in all the sections | as a consequence, NH4+-N is a major pollution index in the entire Fujiang River. In some sections, TP, CODMn and BOD5 yield high pollution load sharing ratios. The distribution of the main pollution sources of different sections shows that the pollution indexes exceeding standards are mainly influenced by various pollution factors, such as cultivation, industrial wastewater, urban and rural domestic sewage, and agricultural non-point sources. Therefore, relevant preventive measures and recommendations are provided as a reference of the comprehensive control of water pollution in the Hechuan segment of Fujiang River.