The water level of Poyang Lake is affected by both the Yangtze River mainstream and the Fiver Rivers (namely, Ganjiang River, Fuhe River, Xinjiang River, Raohe River and Xiushui River) in the lake basin. The runoff of the Five Rivers is the main inflow of Poyang Lake. In order to explore the temporal and spatial impact of the Five Rivers on the water level of Poyang Lake, the response of Poyang Lake level variation to the runoff change of the Five Rivers was quantitatively studied by data-driven simulation and sensitivity analysis. Firstly, the lake level prediction model was established by combining PSO-GA algorithm and support vector regression (SVR) technology. The temporal sensitivity of water level of Poyang Lake to runoff change of the Five Rivers was simulated. Then, based on this model, the spatial distribution characteristics of water level response of Poyang Lake to runoff change of the Five Rivers were studied using continuous model simulation. The results show that the most sensitive period that Poyang Lake level response to the runoff change of the Five Rivers is from May to July, especially in May. In terms of spatial distribution, water level in the middle part of Poyang Lake is most sensitive to the runoff change of the Five Rivers. For instance, based on the data in May 2010, when the runoff of the Five Rivers was increased by 40%, water level at Duchang station was averagely increased by 1.16 m within one week; Average water level increased at Xingzi station and Hukou station in the north lake area was 1.15 m and 1.03 m, respectively, and that at both Tangyin station and Kangshan station in the south lake area was 0.97 m. This study clarified the temporal and spatial response characteristics of water level of Poyang Lake to runoff of the Five Rivers, and provides scientific basis for water resources management and water projects optimization in the Poyang Lake basin.

Carrying out quantitative assessment of regional water security is an important basis for water security diagnosis and scientific decision-making. To analyze temporal-spatial characteristics of water security in Gansu Province, an index system of 2 system layers, 6 criteria layers and 25 evaluation indexes was constructed. Based on the combination weighting method of improved AHP and entropy weight method, the weight of each index was calculated. The water security status of 14 cities (states) in Gansu Province in 2010, 2015 and 2020 was comprehensively evaluated by cloud model. The results show that the water security of each city (state) is on the rise in 2010, 2015 and 2020, and it is generally in the basic and relatively security level. The shortage of water resources and flood and drought disasters are the main restrictive factors that affect the water security in Gansu Province. Improving water resources conditions and modern water management level are the important measures to improve the water security in Gansu Province.

The evaluation of carrying capacity of water resources in the middle reaches of the Heihe River is important to promote the efficient use of water resources and sustainable economic development of the region. This paper quantitatively analyzed the dynamic changes of the water resources carrying capacity of the middle reaches of the Heihe River from 2000 to 2020 by selecting 10 evaluation indexes and using the fuzzy comprehensive evaluation model. The results show that the water resources carrying capacity of the region is between 0.3 and 0.5, with the highest value reaching 0.471 in 2020, and the water resources carrying capacities are in a bearable state. In order to improve the rational and efficient use of water resources, the middle reaches of the Heihe River should adjust the water use structure and strengthen the development of water-saving economy and ecological environmental protection.

In order to solve the control problem of rainfall runoff and pollutants in highway service area, SWMM model was used to establish hydrology and water quality model of Tieshan service area. Based on the selection principle of LID measures and the site conditions of Tieshan service area, the control efficiency of rainfall runoff and pollutants in the service area were studied under four schemes of without LID measures, combination of infiltration pavement and green roof, combination of sunken lawn and green roof, and combination of permeable pavement and sunken lawn under different rainfall return periods. The results show that the three combined LID measures can effectively reduce the rainfall runoff, peak runoff, pollutant concentration and total pollutant load in the service area, among which the LID combined measure scheme of permeable pavement and sunken lawn has the best effect on pollution interception and emission reduction. In addition, the LID measures are more effective in controlling rainfall runoff and pollutants when the rainfall intensity is low than that is high.

The ecological and economic value of water resources is the unity of economic value, social value and ecological environmental value. It is of great significance to analyze the change rule of its value for rationally optimizing the allocation of water resources, promoting the sustainable development of the ecological and economic system of water resources. The emergy theory analysis method was used to calculate the ecological and economic value of water resources in Zhengzhou City from 2009 to 2020. Its time evolution law and influencing factors were discussed, and its future development trend was analyzed by R/S analysis method. The results show that there is a growing trend for water ecological economic value in Zhengzhou City on the whole. The value change is mainly affected by GDP, per capita disposable income, sewage wastewater emissions and other factors. The results show that the future trend in the past time series characteristics were positively related, namely, water ecological economic value in Zhengzhou City still showed a trend of growth in the future.

In order to reveal the pollution characteristics of heavy metals in surface sediments in the upper reaches of the Zhanghe River, the chemical fractions and contents of Cr, As, Cd and Pb in 32 samples were determined. The potential ecological risks were assessed by rations of secondary phase and primary phase, and risk assessment code method. The correlation analysis was used to analyze the sources of heavy metals. The results show that the average contents of heavy metals Cr, As, Cd and Pb are 91.51±24.30, 9.81±3.05, 0.12±0.05, 18.30±5.43 mg/kg, respectively, and only the average contents of Cd do not exceed the background value. Only the content of Cd does not exceed the background value. The exchangeable fraction of Cd is larger than Cr, As, and Pb, and its biochemical activity is relatively high. The potential risks of heavy metals are sorted as Cd>Pb>As>Cr, and the risks are mainly concentrated in the source of Zhuozhang River and the west headwater of Qingzhang River. These four heavy metals mainly come from mineral exploitation, and mining activities contribute to the content and potential risks of heavy metals.

Huaxi Reservoir is a typical karst mountain reservoir and an important water source in Guiyang City. In order to find out the distribution of heavy metals in the sediment of Huaxi Reservoir, a total of 21 sets of sediment samples were collected from two cross sections. The content of Cr, Cu, Zn, As, Cd, Pb and other heavy metal elements were determined by inductively coupled plasma mass spectrometer (ICP-MS). Their distribution characteristics and content levels on the cross section were analyzed. The potential ecological risk assessment method and geo accumulation assessment method were used to evaluate the pollution risk, and systematically analyze the degree of heavy metal pollution in two different sections of the reservoir. The results show that the content of heavy metals in the section of inlet reservoir is low and lower than the background value, and its concentration sequence is Zn>Cr>Cu>As>Pb>Cd; The heavy metal content has a law of decreasing with the increase of the offshore distance, the main reason is caused by the influence of surrounding agricultural activities; The content of heavy metals in open sections is relatively low, and the concentration sequence is Zn>Cr>Cu>Pb>As>Cd; The heavy metal content increases from the left bank to the right bank, which is mainly related to river velocity and sediment particle size. The heavy metal pollution in the sediment of the reservoir is light pollution, and the pollution degree of the section near the reservoir is right bank>left bank>river center, and the pollution degree of each heavy metal in the open section gradually increases from left bank to right bank.

This paper selected 6 typical cape-bay sandy beaches in Wenzhou area to sort out the natural environment. The parabolic plane morphology model (MEPBAY) was used to compare the relative positions of the static simulated shoreline with the recent actual shoreline. The advancing and retreating trend of the coastline of the shaped sandy coast was analyzed. The current stability of the coastal beaches of Cape Bay in Wenzhou area was discussed. The results show that the coastline is in a stable state as a whole, and the profile of sandy beaches is mainly divided into four types: concave downward, upward convex, slope, and slope + upward convex combination. The characteristics of the interannual erosion and deposition changes of the profile are mainly divided into three modes: the upward erosion and the downward siltation, the overall erosion type and the basic stable type.

Taking Jinghe River Basin in Gansu Province as the main research object, the Jinghe River trunk canal irrigation area in the upper reaches of Jinghe River was selected as a typical experimental irrigation area. The irrigation return water, farmland water content and crop growth trend of Jinghe River trunk canal irrigation area were monitored. The water consumption of Jinghe River trunk canal irrigation area was tested by the combination of diversion and drainage difference method and multi-level soil water balance model (VSMB model). According to the monitoring experiment, the total water diversion volume of Jinghe River main canal irrigation area in 2018 is 20.76 million m³, and the total water return volume is 5.23 million m³. The water consumption coefficient of Jinghe River main canal irrigation area is 0.56 by using the diversion and drainage difference method. The total annual water diversion of typical plots in Gannong experimental field is 1 901 m³, and there is no retreating water on the surface. The water consumption coefficient obtained by diversion and discharge difference method is 0.75, and the water consumption coefficient obtained by VSMB model is 0.71. The research results provide reference for the study of water consumption coefficient of other agricultural irrigation areas in Jinghe area, and have certain guiding significance for irrigation area planning and design and high-efficiency agricultural irrigation pilot work.

In order to accurately describe the water environment quality of Shiyang River Basin and clarify the main pollution factors of water quality, according to the analysis results of water quality data of typical sections of Shiyang River Basin in Gansu Province, five pollution factors including dissolved oxygen, chemical oxygen demand, ammonia nitrogen, total phosphorus and fluoride were selected as water quality evaluation indexes. A combined weighting comprehensive evaluation model based on CM-AHP and entropy weight method was established to study the main pollution factors of Shiyang River Basin. The results show that the combined weight of total phosphorus and ammonia nitrogen pollution accounted for the largest proportion, reached 0.438 and 0.296, respectively, which were the main pollution factors of Shiyang River. The water quality of Shiyang River Basin gradually deteriorated from the upstream to the middle and lower reaches.