,- Chengdu University of Technology, Chengdu, China (zhangq@cdut.edu.cn)
The Ningnan region, located in the Jinsha River hot-dry valley of southwest China, faces severe groundwater scarcity and declining water levels, threatening local production and daily life. This study investigates the drought characteristics and mechanisms of groundwater resources under the combined impacts of climate change and tunnel construction, addressing the limitation of traditional single-factor assessments.
Field surveys, remote sensing interpretation, hydrochemical and isotopic analyses were conducted to clarify groundwater occurrence, recharge-discharge processes, and karst development. Climate data statistics, NDVI-based vegetation coverage analysis, and analytical calculations were used to quantify the impacts of these factors. A 3D "climate-groundwater-tunnel" coupled seepage model (Visual MODFLOW) was established to simulate the evolution of the seepage field.
Key findings: (1) Groundwater is dominated by carbonate karst water, with atmospheric precipitation as the primary recharge source. (2) Annual precipitation decreased by 46.17% from 2020 to 2023, while vegetation coverage (exceeding 50%) dropped by 16.47% from 2019 to 2024. (3) Water inflow of the tunnel group ranged from 4537.47 to 63051.93 m³/d, with a maximum impact radius of up to 8806.98 m. (4) Numerical simulation showed that natural groundwater levels declined by 0.5–7.5 m due to drought; tunnel construction caused maximum drawdowns of 130 m (Ningnan Tunnel) and 200 m (Ningqiao Tunnel). (5) A survey of 47 typical points indicated that 66% experienced moderate to severe drought, 71.4% of which were jointly affected by tunnel drainage and reduced precipitation.
Conclusion: Groundwater drought within tunnel impact zones results from the combined effects of climate change and human activities, while areas outside the zones are mainly affected by climate change. This study provides a theoretical basis for groundwater protection and restoration in the Ningnan region.
How to cite: Zhang, Q., Wang, W., and Sun, J.: Drought Analysis of Groundwater Resources in the Ningnan Region Under the Combined Effects of Climate Change and Human Activities, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7632, https://doi.org/10.5194/egusphere-egu26-7632, 2026.
