Combined CA-ANN, CMIP6 GM and SCS-CN modeling of future impacts of climate change and urbanization on potential natural groundwater recharge at city scale

Abstract

Rapid urbanization and climate change are critical processes that affect groundwater resources, particularly in urban areas. This study investigates the long-term impacts of both processes on the potential natural groundwater recharge from precipitation across the period 1986-2100 under SSP2-4.5 and SSP5-8.5 pathways. The approach used in this study combines three models, including (1) a Cellular Automata-Artificial Neural Network (CA-ANN)-based modeling for the continuous mapping of future spatiotemporal land use-land cover (LULC) distributions, (2) climate change modeling using CMIP6 GM, and (3) hydrological modeling using the Soil Conservation Service-Curve Number method (SCS-CN). The findings indicate that the urban area is anticipated to increase from 18.2% of the total area in 1986 to 86.5% by 2100 at the expense of other land cover. Moreover, projected climate change indicators derived from precipitation exhibit declining trends in yearly precipitation and extreme event frequency and intensity against an increasing dry conditions trend during the period 2017-2100. The analysis reveals a fluctuating future potential natural groundwater recharge with decreasing trends under both climate change pathways. The regression analysis shows that 27.5% (R² = 0.8199) and 24.7% (R² = 0.7867) of precipitation contribute to natural recharge under SSP2 and SSP5, respectively, highlighting a strong linear correlation between them. In comparison to a high emission pathway, these slopes indicate that achieving a moderate emission pathway will increase the potential recharge by 2.8%. In addition, the outcomes demonstrate that future groundwater recharge patterns are more sensitive to changes in climatic conditions than to urbanization. This study underscores the importance of integrating urban planning and water resources management strategies to ensure the long-term groundwater sustainability in urban cities.

Keywords: CA-ANN; CMIP6 GM- SCS-CN; Climate change; Groundwater recharge; Urbanization.