[A-HW18] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW18-04] Impact of Land use change on groundwater recharge in an emerging suburban catchment——Evaluation for Sustainable water use

*Sharon Bih Kimbi¹, Kunyang Wang¹, Shin-ichi Onodera¹, Yuta Shimizu², Ichirow Kaihotsu¹ (1.Graduate School of Advanced Science and Engineering, Hiroshima University, 2.Western Region Agricultural Research Center, National Agriculture and Food Research Organization, 6-12-1 Nishifukatsu-cho, Fukuyama-shi, Hiroshima 721-8514, Japan)

Keywords:Urbanization, Forest Evapotranspiration, Kurose basin, Raster resolution, SWAT

Globally, urbanization has affected the land-use practices of many cities. The reduction in natural land area and the increase in impervious cover alters the water balance, especially within the catchment area, affecting groundwater availability. Groundwater has long been a major source of water supply in Japan, and as the country entered a rapid phase of industrialization and urbanization around the 1960s, there was an obvious increase in the pressure on the groundwater resources regionally. Thus, knowledge of the expected changes with increasing urbanization at the catchment scale is of paramount importance. This study aims to provide insight into the impacts of land use change on groundwater recharge by conducting a water balance estimation using the Soil and Water Assessment Tool for the 1980s and the 2000s in the Kurose River basin.
Results suggest that mean annual groundwater recharge decreased by approximately 34.9% over the past three decades. Land use change analysis was conducted from 1986 to 2006 by using land use maps at different resolutions. Groundwater recharge simulation results were affected by resolution scaling at both 10 m and 100 m spatial resolutions. Nevertheless, the forest cover and urban areas could not be accurately depicted at 100 m and 10 m resolutions. Across the entire study area, long-term temporal changes in land use had a significant impact on groundwater recharge and forest ET. Overall, we demonstrated the sensitivity of catchment to land-use changes caused by anthropogenic activities; this would help future urban planning projects to minimize undesirable impacts on groundwater recharge while striving for sustainable water management.

This study is supported by Asia-Pacific Network for Global Change Research (APN) (CRRP2019-09MY-Onodera)