Mountain river floods pose a serious threat to the safety of foothill urban areas. Constructing flood detention and storage zones in front of mountainous regions can retain floodwater，reduce flow velocity，attenuate flood peaks，and effectively mitigate the impact of floods on developed areas. Taking the Beisha River in the Wenyu River Basin，Beijing，as a case study，this research employs a numerical simulation method based on hydrodynamic principles to simulate the flood evolution processes under two scenarios： free flood discharge and discharge regulated by flood detention zones. By comparing the flood risks and spatial distributions under different return-period floods before and after the construction of detention zones，the effectiveness of flood control and disaster mitigation was evaluated.The results indicate that： under various return-period flood scenarios，the foothill detention zones along the Beisha River can significantly reduce downstream flood peaks，inundation extent，and water depth，thereby lowering regional flood risk； the overall mitigation effect is constrained by the scale of the detention zones — under the 20-year flood scenario，the Beisha River detention zone achieves the highest mitigation benefit，reducing GDP losses by 27.55%，followed by 22.45% under the 50-year design flood； numerical simulation of flood processes provides an effective means to quantitatively analyze and assess the mitigation performance of planned or ongoing flood control projects，through comparative analysis of flood risks before and after project implementation.

The long-term over-extraction of groundwater in Hengshui City has led to a continuous decline in the deep groundwater levels， which in turn has caused serious ground subsidence issues， threatening the sustainable development of the regional economy and ecological environment. Studying the distribution characteristics of ground subsidence and its response relationship with deep groundwater levels is of great significance for preventing and controlling subsidence disasters and formulating scientific policies for groundwater development and utilization. This study is based on SBAS-InSAR data and deep groundwater level monitoring data from 2018 to 2022. It analyzes the characteristics of ground subsidence in Hengshui City and its response relationship with deep groundwater level changes across three time scales： multi-year averages， inter-annual variations， and monthly fluctuations. Using the cross-wavelet transform analysis method， this research quantitatively investigates the periodic characteristics of ground subsidence and deep groundwater level evolution and their time-lag relationships at representative points. The research results indicate that： （1） From 2018 to 2022， Hengshui City was in a state of subsidence as a whole， with areas that have a cumulative subsidence of over 100 mm accounting for 86.54%. This has formed two distinct subsidence zones， one stretching from Raoyang to Shenzhou and the other at the junction of Jizhou-Zaoqiang to the boundary between Fucheng County and Jingxian County. （2） The study area was in a “rapid subsidence” phase from 2018 to 2019， with the highest subsidence intensity occurring in Anping County and Raoyang County. After 2020， it entered a "slow subsidence" phase， where the recovery of deep groundwater levels significantly slowed down the subsidence rate. By 2022， the average subsidence amount decreased to 4.7 mm. However， some areas continued to experience further subsidence as their groundwater levels were lower than the historical minimum groundwater levels. （3） The groundwater level falling below the historical minimum groundwater levels is a key driving factor for subsidence， and the resulting inelastic compression is the main component of the subsidence amount. This indicates that preventing deep groundwater levels from falling below historical lows is an effective measure for controlling ground subsidence. （4） The average time lag between ground subsidence and changes in groundwater levels at six representative points is 38.83 to 66.99 days， demonstrating a significant lag effect in the compaction of aquifers in the area. The findings of this study can provide a scientific basis for subsidence prevention and control， water resource management， and regional sustainable development in the Hengshui area.

Sand liquefaction caused by strong earthquakes is receiving increasing attention due to the frequency of extreme seismic events. The liquefaction possibility assessment is the primary task in the study of sand liquefaction. In this paper，a probability assessment model is established based on the field investigation of liquefaction cases，combined with the knowledge of probability statistics and logistic regression algorithm. The effectiveness of the model is verified by comparing with the existing deterministic liquefaction assessment methods. Furthermore，the parameters analysis affecting the liquefaction assessment results is also conducted. The results show that the liquefaction discrimination model established in this paper has a success rate of 85.70% and 82.50% for rejudging the liquefaction and non-liquefaction cases； and a success rate of 88.00% and 72.00% for the discrimination of the validation set， demonstrating a good discrimination success rate. The fine particle content， overburden stress correction factor，the correction coefficient for overburden stress，and the adjustment coefficient for seismic magnitude should be applied to correct case data when applying this model to assess liquefaction potential，which can improve the accuracy of sand liquefaction assessment.At the same time， the model can provide specific discrimination formulas. In the future， when new samples are incorporated， the model can be further improved by adjusting and modifying based on various parameters.

The construction of Low Impact Development （LID） facilities has a significant impact on alleviating urban waterlogging disasters. To study the effect of LID facility construction on rain and flood control in the northern plain area， this paper constructs a Storm Water Management Model （SWMM） based on the district as the base of the central urban area of Hengshui city， analyzes the current pipe network flow capacity， and simulates and compares the rain and flood control effects before and after the construction of LID facilities in the central urban area from the aspects of annual total runoff control rate and flood risk. The simulation results show that the drainage capacity of the central part of each area in the central urban area is relatively lower than that of the surrounding areas. More than 50% of the pipe network has a good drainage capacity， but about 30% of the pipe network still needs to be renovated. After the construction of LID facilities， the annual total runoff control rate in the central urban area has significantly increased to 76%， an increase of 14% compared with the development and construction before. The annual total runoff control rate of each key district has reached more than 75%. By comparing the flood risk in the built-up area of the central urban area under a 30-year return period 24-hour rainfall （cumulative rainfall of 195.7 mm） before and after the construction of LID facilities， the flood risk area has decreased by 4.46 km² after the construction， and all 8 severe flood waterlogging points that appeared before have been eliminated. The flood prevention standard area is about 71.59 km²， accounting for 93.3% of the built-up area， and the flood prevention standard area has reached the standard. The construction of LID facilities in the central urban area can effectively cope with a 30-year return period of heavy rain.