To address the prominent problem of declining runoff in many rivers around the world, studying the law of runoff change and attribution analysis is very important for the planning and management of watershed water resources and has practical significance for solving the imbalance between supply and demand of watershed water resources and maintaining the healthy development of rivers. Three commonly used coupled water-energy balance equations based on Budyko hypothesis are selected to estimate the elasticity coefficient of runoff change to each driving factor, and the contribution rate of different factors to runoff change in the study area is quantified by the total differential method and the complementary method, respectively. The results show that the runoff of Huangfuchuan River basin showed a significant decreasing trend from 1954 to 2015, and the runoff mutation points were 1979 and 1996; in the alteration period I (1979–1996), precipitation was the main factor leading to the runoff reduction in Huangfuchuan River basin, followed by the influence of underlying surface; the contribution rate of underlying surface to runoff alterations ranged from 63.7% to 65.46%; the impact of potential evapotranspiration was slightly smaller. In the alteration period II (1997–2015), the underlying surface played a dominant role in runoff reduction of Huangfuchuan River basin. The contribution rate of the underlying surface to runoff change ranged from 80.21% to 86.34%, followed by precipitation, and the potential evapotranspiration had the least impact. The impact of human activities on the whole watershed increased with the passage of time. The land use change, the overall increase of NDVI (vegetation cover) and the construction of water conservation projects are important reasons for the reduction of runoff in Huangfuchuan River basin.

In order to utilize reclaimed water resources reasonably and efficiently, it is necessary to strengthen the evaluation of reclaimed water. However, a major problem with traditional reclaimed water assessment methods is that it mostly focuses on a single aspect. In this study, an evaluation model of comprehensive development level of reclaimed water which consists of four layers with three criteria and 17 indicators is established. An improved catastrophe theory was utilized to obtain diversely distributed adjusted assessment values of comprehensive development level of reclaimed water. Finally, the single-factor sensitivity analysis was performed on the aforementioned model, and the sensitivity sequence of each indicator was determined according to the comprehensive development ability of reclaimed water. The results showed that 1. In Yunnan Province, the comprehensive development level of reclaimed water grew steadily from 2012 to 2015 but declined in 2016. Water deficiency was the most sensitive factor, followed by wastewater discharge, grade 1B treatment level, and construction impact as the secondary sensitive factors. 2. Compared with the fuzzy comprehensive evaluation method, the improved catastrophe evaluation method has the advantages of the rigorous theory, concise model, and simple calculation, and the decision result is more objective and reliable.

Under a changing environment, the characteristics of precipitation-runoff hydrological response relationship and the analysis of synchronous and asynchronous encounter frequency in large river basins play a crucial role in the water resources ...