极端降水引发地下水位上升对城市韧性的影响:以北京为例OA

[Objective]Under the new hydrological conditions,the groundwater level in Beijing has been continuously rising and has reached a historical high,posing a threat to urban safety.Extreme precipitation has further accelerated this groundwater rise,making it urgent to investigate the response mechanism of shallow groundwater to extreme precipitation events,assess the impact of groundwater level rise on urban resilience,and explore strategies for groundwater regulation.[Methods]Taking 2021 and 2023-two years with extreme precipitation events-as examples,the percentile thresholds of extreme precipitation were calculated,and the spatiotemporal distribution characteristics of precipitation in the multi-year average(1983-2023),2021,and 2023 were analyzed.Based on data from 360 shallow groundwater monitoring wells in the study area,the response process of shallow groundwater levels to extreme precipitation events in extremely wet years was quantitatively analyzed.[Results]The result showed that:(1)the annual average precipitation in Beijing over the past 40 years,in 2021,and in 2023 was 564.9 mm,864.5 mm,and 690.0 mm,respectively.Precipitation was mainly concentrated between June and September,with 2021 being the wettest year in the past 40 years.(2)Among 20 typical meteorological stations in Beijing,the 95％thresholds for extreme precipitation in 2021 and 2023 were 23.0～56.6 mm and 19.3～89.7 mm,respectively.The number of extreme precipitation days during the year ranged from 4 to 6 in 2021 and from 3 to 5 in 2023.The annual contribution of extreme precipitation ranged from 35.5％to 56.7％in 2021 and from 28.1％to 67.1％in 2023.The intensity of extreme precipitation ranged from 45.3 to 123.1 mm·d-1 and from 25.8 to 217.8 mm·d-1,respectively.The annual maximum daily precipitation ranged from 48.4 to 223.3 mm and from 37.9 to 306.8 mm,respectively.(3)A comparison of groundwater levels between the wet and dry seasons in 2021 and 2023 showed that the groundwater level generally increased by 0～5 m,with the maximum annual increase exceeding 15 m.(4)The groundwater depth in urban areas was generally less than 20 m,with leakage occurring along some metro lines.The infiltration capacity of rainwater storage and flood regulation project in the western area was significantly reduced.[Conclusion]Due to differences in surface permeability,piedmont areas are more receptive to atmospheric precipitation recharge than those in the eastern and southern plains.However,different rainfall types result in different recharge effectiveness for groundwater.Long-duration continuous precipitation provides more effective groundwater recharge than short-duration intense rainfall.Elevated groundwater levels affect the normal operation of metro systems,underground structures,and urban flood control projects.Coupled with rapid recharge and slow discharge of groundwater,the additional recharge from extreme precipitation poses a serious challenge to urban resilience.Therefore,it is essential to develop scientifically grounded urban resilience plans that consider groundwater recharge and discharge characteristics and the impacts of extreme precipitation.