The scientific and accurate evaluation of water resources carrying capacity has good social, environmental and resource benefits. Reasonable selection of evaluation parameters is the key step to realize efficient and sustainable development of water resources. Taking Zanhuang County in the North China Plain as the research area, this study selected fuzzy comprehensive evaluation models with different weights in the established evaluation index framework to explore the sources of uncertainty affecting the evaluation results of water resources carrying capacity. By using the sensitivity analysis method of index weight, the index with the biggest influence factor on the evaluation result is selected to reduce the uncertainty problems such as index redundancy and small correlation degree. The results show that the correlation and reliable of comprehensive evaluation value obtained by different weight methods is different. The evaluation result obtained by using the analytic hierarchy process is more relevant than the entropy weight method, and it is more consistent with the actual load-bearing situation. The study of sensitivity index shows that water area index is the biggest factor affecting the change of evaluation results, and water resources subsystem and socio-economic subsystem play a dominant role in the whole evaluation framework. The results show that strengthening the data quality control of index assignment and weight method is helpful to reduce the error of water resources carrying capacity evaluation. It can also provide scientific basis for the improvement of fuzzy evaluation model.

Precipitation is a critical factor affecting regional water cycles, water ecology, and socioeconomic development. Monthly precipitation, water vapor pressure, and temperature datasets from 613 meteorological stations across China were used to analyze the spatiotemporal evolution of urban rain island effects at the national scale during periods of slow (1960–1969) and accelerated (2010–2019) urbanization. The combined effects of artificial water dissipation and heat islands on urban precipitation were a key focus of this study. The results showed that rain island effects (0–31.6 mm/month) were primarily distributed along the southeast coast (dominated by the heat island effect) and northwest inland region (dominated by artificial water dissipation). During winter, the relative contribution of artificial water dissipation was higher in urban areas, and the rain island effect was more apparent than in the summer. Comparisons of precipitation prior to and following large-scale urbanization showed that precipitation and rain island intensity along the southeast coast and northwest inland region increased by 0–28 and 0–28.6 mm/month, respectively. These findings indicate that artificial water dissipation is an important water vapor source for urban precipitation, particularly during winter months.

Groundwater is an important source of water in Beijing. Hydrochemical composition and water quality are the key factors to determine the availability of groundwater. Therefore, an improved integrated weight water quality index approach (IWQI) combining the entropy weight method and the stochastic simulation method is proposed. Through systematic investigation of groundwater chemical composition in different periods, using a hydrogeochemical diagram, multivariate statistics and spatial interpolation analysis, the spatial evolution characteristics and genetic mechanism of groundwater chemistry are discussed. The results show that the groundwater in the study area is weakly alkaline and low mineralized water. The south part of the study area showed higher concentrations of total dissolved solids, total hardness and ${\mathrm{NO}}_3^{-}$-N in the dry season and wet season, and the main hydrochemical types are ${\mathrm{HCO}}_3^{-}$-Ca and ${\mathrm{HCO}}_3^{-}$-Ca-Mg. The natural source mechanism of the groundwater chemical components in Chaoyang District includes rock weathering, dissolution and cation exchange, while the human-made sources are mainly residents and industrial activities. Improved IWQI evaluation results indicate that water quality decreases from southwest to northeast along groundwater flow path. The water quality index (WQI) method cannot reflect the trend of groundwater. Sensitivity analysis indicated that the improved IWQI method could describe the overall water quality reliably, accurately and stably.

The human risk assessment model can serve as a tool for regional contaminated site comprehensive management. However, site-specific risk assessment is still seldom applied in China as a basis for making decisions on risk management actions. In this study, a total of 112 soil samples were collected from ten polluted sites in Southwest China. The human health risk assessment method was used to assess the risk of Cd, As, Cu, Pb, Cr, Zn, and Hg pollution. According to the findings, the average concentrations of As, Zn, and Pb in contaminated sites are substantially higher than those of Cu, Cd, Cr, and Hg. Further studies conclusively showed the soil at contaminated site in its present condition pose risk to human health to potential future receptors. The main contribution of non-cancer and cancer risks was through incidental soil and dust ingestion. The priority control site remediation order is Region VI > Region V > Region IV > Region III > Region VII > Region X > Region IX > Region VIII > Region I > Region II. Finally, management recommendations are made, including reducing pollutant intake, implementing a stringent monitoring scheme, utilizing bioremediation, and strengthening the implementation of relevant laws. This study provides a case for the comprehensive evaluation of soil pollution at contaminated sites in China.