To explore the storage effect of functional zoning on different layout methods of LID facilities in industrial parks and identify the optimal LID facility combination scheme, a specific industrial park in Guangdong Province was selected as the subject of study. The software SWMM was employed to investigate the storage effect of individual LID facility layouts and the comprehensive storage benefits of various LID facility combination schemes. The results show that affected by the park's functional zoning, when the downstream greening positions in the study area are concentrated and the rainfall is relatively low, LID facilities installed in the middle of the concentration area demonstrate superior effectiveness compared to those installed downstream. As the rainfall increases, the downstream's storage advantages become fully apparent. When designing LID facility combinations, the scheme combining 5% green roofs and 15% sunken green spaces yields the best storage effect per unit layout area. However, due to the mutual influence among facilities, the effectiveness of this combination scheme is not as good as the arithmetic sum of the data for the individual facilities, failing to produce the desired synergistic effect of "1+1>2".

In order to solve the real-time online flow monitoring under complex conditions of wide and shallow river sections, based on the applicability of conventional online flow measuring equipment, the combined application of two-way probe H-ADCP facing each other was proposed. Taking the Gaogang Water Conservancy Project at the source of water intake of the East Route of the South-to-North Water Transfer Project as an example, the whole process of numerical simulation of river sections, flow field analysis, equipment installation, comparison measurement setting and other aspects were carried out applied research. The results show that the change of flow field in the flow measuring reach is complicated under different operation conditions of the control hub gate pump. The dual probe H-ADCP can be installed at the same section and the same height, and the ultrasonic beam crossing will not affect the collection of effective unit velocity data. The relationship between the double index velocity and the average velocity of the section can be established to calculate the real-time flow, and the accuracy of the combined applied flow measurement is higher than that of the single H-ADCP flow measurement data. The research results form a set of real-time flow monitoring application methods under complex conditions of wide and shallow rivers, which can provide ideas for the combined use of online flow measuring equipment.

In view of the sudden water pollution events in the main stream of Minjiang River, taking the lower reaches of the main stream of the Minjiang River as the study area, a coupling model of hydrodynamic and water quality was established to accurately simulate the flow dynamics and water quality changes under different scheduling scenarios. By comparing four different scheduling strategies: background simulation (i.e. no special scheduling measures), single optimization of Qianwei Avionics Water Conservancy Project, single optimization of Longxikou Avionics Water Conservancy Project, and joint optimization of two projects, this study comprehensively evaluated the emergency treatment ability of each strategy for water pollution in the main stream of the Minjiang River. The results show that from the point of view of pollutant concentration peak and pollutant exceeding standard time, the joint scheduling strategy of increasing the sluice flow of two hub projects simultaneously shows the best pollution group disposal effect. This strategy not only significantly reduces the peak concentration of pollutants, but also effectively shortens the period of time when pollutants exceed the standard, thus minimizing the negative impact of water pollution on the environment and ecology. The research results can provide reference for the emergency treatment of the Minjiang River main stream water pollution incident and improve the emergency treatment efficiency.

In order to meet the flood discharge and irrigation requirements of tributary channels, it is of great practical significance to master the water flow diversion characteristics of the three-branch river channel. Based on numerical simulation and physical model experiments, the water level changes, velocity distribution, and flow allocation characteristics at the mouth of three tributaries river under different branching angles were studied. The results show that for a three-branch river channel, the larger the branching angle, the smaller the flow velocity in the tributary is, and the flow allocation in the variable angle side gradually decreases, while the flow allocation in the fixed angle side and the main branch gradually increases. Based on dimensional analysis, a three-branch river flow diversion ratio calculation formula was obtained considering the Froude number at each branch inlet. The formula was verified, and it was found that the prediction accuracy of the formula for the flow diversion ratio of the tributary channels in a three-branch river system was good.

The Leizhou Peninsula exhibits one of the highest incidences of drought within the Pearl River Basin. Research on the characteristics and response mechanisms of meteorological and hydrological droughts in this area holds significant theoretical and practical importance for understanding drought patterns in regions with abundant rainfall yet fragile water resource systems. Based on the monthly meteorological and hydrological data from the representative station in Leizhou Peninsula, the standardized precipitation-evapotranspiration index (I_SPEI) and standard runoff index (I_SRI) were used to analyze the variation patterns of meteorological drought and hydrological drought in this region from 1970 to 2016. The Mann-Kendall trend test method, moving average method and Morlet wavelet analysis method were adopted to analyze the changing trends and cycles of meteorological drought and hydrological drought in this region at different time scales (3 and 12 months). Propagation characteristics of meteorological drought to hydrological drought were examined using the run-length theory. The results show that the meteorological drought in Leizhou Peninsula is increasing during the study period. Particularly, the 12-month I_SPEI obtained from Zhanjiang station and Xuwen station decreased significantly, at the rate of -0.014/month and -0.008/month, respectively. However, no obvious trend of hydrological drought was detected. Both drought types showed multi-scale periodicity, sharing a primary first-order period of 20 years in the north and 14 years in the south. The main cycles of meteorological drought and hydrological drought in the south and north are consistent, and the variation patterns are relatively synchronous. Hydrological drought in the southern peninsula demonstrated stronger responsiveness to meteorological drought than the northern region.

To solve the problem of decreasing prediction accuracy caused by nonlinear runoff sequence and instability of single prediction model, this paper proposes a "selection-combination-correction" modeling strategy based on the "decomposition-prediction" model. Firstly, five models including DNN, SVM, LSTM, TCN, and GBRT are used to establish 15 coupled models based on EMD, CEEMDAN, and VMD, and the models are selected. Then, the selected model is used as the base model, and the predicted results of each period of the base model are processed and input into a multi-layer perceptron to construct a new combination model. A residual correction equation is constructed for the test period of the combination model to further improve the prediction accuracy. Finally, the method is applied to the test studies of Huaxian Station in Weihe River Basin and Yangxian Station in Hanjiang River Basin. The results show that the combination model constructed by the multi-layer perceptron has higher prediction accuracy than the single model, and can integrate the advantages of other models to improve the model's generalization ability. The model with residual correction technology is superior to the combination model in all aspects, especially in the fitting of peak discharge, further improving the prediction accuracy.

In order to evaluate the applicability of the latest generation GPM IMERG satellite precipitation products in Jiangsu Province, the measured precipitation data of 73 ground stations were selected as references. Using statistical indicators and extreme precipitation index, the accuracy evaluation of GPM IMERG precipitation products were conducted from the perspectives of day, month, season, and their extreme precipitation monitoring capabilities were evaluated. The results show that the GPM satellite precipitation products have good observation effects in Jiangsu region. At the daily and monthly scales, their overall and regional data have a high correlation with ground station measured data (C_CC≥ 0.77), and the correlation becomes more significant with the increase of time scale. At the same time, the GPM satellites overestimate the measured precipitation, and the R_RMSE at the monthly scale is relatively higher. There are certain differences in the observation accuracy of GPM satellites in different seasons, and the winter observation effect is the best, with high correlation and the lowest observation error (C_CC=0.92, R_RMSE=26.37 mm, R_RB=23.4%). The GPM satellite has good ability to monitor extreme precipitation and can observe and describe the occurrence and intensity of extreme precipitation in Jiangsu region, especially in the southern Jiangsu region, with better observation effect.

Under the background of frequent extreme climate events, analyzing the spatio-temporal changes of surface water bodies in the Songhua River Basin affected by climate change over the past 30 years is of great significance for the region to take and optimize climate response measures in advance. Based on the spatio-temporal dynamic changes of surface water area in the Songhua River Basin from 1990 to 2020, seasonal water bodies were classified and analyzed. By using the EC JRC global surface water product dataset and combining with MATLAB software, the time series feature +K-means clustering and dynamic statistical threshold method were adopted to analyze the changing trend of surface water area in the Songhua River Basin in the past 30 years, and to classify the seasonal water body area as well as detect and analyze the recovery dynamics of extreme hydrological years. The results show that during the study period, the seasonal water body area in the Songhua River Basin increased by 114%, while the permanent water body area decreased by 49.46%, and the total surface water area showed an upward trend. The annual seasonal water body area was classified into three categories: fluctuating-wet year, low fluctuation - dry year, and stable - normal year, with a silhouette coefficient of 0.549, indicating a good clustering effect. Two significant high-value years, 1998 and 2013, were identified, and it was analyzed that neither had fully recovered. The research results provide a direction for the effective management and protection of water resources by referring to historical extreme hydrological events and making flood and drought prevention preparations in advance for the Songhua River Basin in the face of future extreme weather.

To explore temporal and spatial variations of extreme precipitation in the Rolling Hilly Region of Northeast China, a set of extreme precipitation evaluation indicators was established using the daily precipitation data from 79 meteorological stations covering the period from 1981 to 2015. The intensity, frequency and persistence of extreme precipitation were analyzed using various methods, including linear trend estimation, coefficient of variation, Mann-Kendall test, R/S analysis, and GIS spatial analysis. The results show that from 1981 to 2015, the overall extreme precipitation showed a weakening trend in the Rolling Hilly Region of Northeast China; R×1day, R×5day, R12D, R50D, and CRED decreased at rates of -0.5 mm/10a, -2.1 mm/10a, -0.2 d/10a, 0.02 d/10a and 0.03 d/10a, respectively. The inter-decade variation of the intensity index showed a state of "rise-fall-rise", and the annual change of frequency index and persistence index showed a "fall-rise" form, which increased by 12.5%-15% in the 2010s compared with the 2000s. The C_V value of frequency index R50D is 0.45, which fluctuates sharply, and the C_V value of other indices is less than 0.2, and the fluctuation range is small. R50D and CRED experienced abrupt changes in 1988 and 1990, respectively, and exhibited an increasing trend before the mutation points and a weakening trend after that. Extreme precipitation increased during the 1990s, weakened in most areas during the 2000s, and intensified in both frequency and intensity in the northern high-altitude areas of the Rolling Hilly Region of Northeast China in the 2010s, while it reduced in the Southern Regions. This study can provide a theoretical basis for formulating strategies to cope with extreme precipitation risks in the Rolling Hilly Region of Northeast China.

Conventional dam displacement monitoring methods are often associated with large errors and low efficiency. Manual monitoring methods cannot provide continuous real-time monitoring, while automated monitoring methods, such as total station robot and GNSS, are affected by weather and have limited accuracy for vertical displacement. To overcome these shortcomings, this study proposes a new intelligent monitoring method for dam displacement based on machine vision. The method utilizes the internet of things and intelligent disaster recognition algorithm to convert picture data into deformation data, enabling ultra-high precision non-contact real-time measurement of the dam. The monitoring system was tested at Lianghui Reservoir, the results demonstrate that the operation of monitoring system is stable, and the horizontal and vertical monitoring accuracy are both 1.5 mm. The proposed method has the potential to be widely applied in other water conservancy projects for surface displacement monitoring.