5:15 PM - 7:15 PM
[AHW27-P10] Anthropogenic Activities Impacts on Groundwater Flow Dynamics in Nara Basin, Western Japan.
Keywords:Groundwater flow model, Hydrogeology, Catchments, Anthropogenic impacts, Surface Groundwater Interaction , MODFLOW
Introduction, and Objectives
Globally, groundwater is extensively utilised for domestic, industrial, and agricultural purposes across several agro-urban catchments, leading to the unsustainable exploitation of limited groundwater resources. This, in turn, results in significant environmental and socio-economic challenges, thereby necessitating the assessment of the interaction between surface and groundwater resources. Nara Basin, an intermontane basin, is characterised by persistent flooding and drought, attributable to its topography, leading to excessive reliance on groundwater resources for domestic and intensive rice paddy cultivation. However, in recent decades, there has been barely research on the groundwater conditions in the Nara Basin considering the significant development of agricultural activities and land-use changes.In this study, we evaluate the impacts of over-abstraction on groundwater flow dynamics resulting from anthropogenic activities in the Nara Basin using a three-dimensional groundwater modelling approach.
Methodology
The groundwater flow dynamics is being simulated using MODFLOW 6 particularly the streamflow routing package for the rivers, recharge, and multi-aquifer well package for groundwater abstraction, over a period of 10 years (2000 – 2009). For assessing the interaction between surface and groundwater the streamflow routing package is being adopted. Whereas the hydrostratigraphic units of the basin were created using the available borehole logs. The model calibration would be conducted utilising Independent Model Parameter Estimation and Uncertainty Analysis (PEST) coupled with spatially distributed observation wells in the Nara Basin. While RMSE (Root Mean Square Error) and R2 correlation metrics would be used to evaluate the model performance.
Results and Discussion.
A simulated groundwater flow pattern directed towards the centre of the basin is probable, considering the possibility of a high groundwater head in the northernmost and southernmost region with higher elevation, whereas a lower groundwater heads in the centre of the basin. However, there could be an alternation in this regional flow pattern due to anthropogenic influence particularly over abstraction of groundwater for water supply, and reduction in recharge due to land-use and climate changes. Furthermore, the occurrence of river leakages and seepages to and from the aquifer is likely at various sections of the river, and play a crucial role in evaluating the interactions between surface and groundwater within the basin.
The findings of this research would broaden the understanding of the groundwater flow dynamics on a catchment-based approach, river-aquifer interactions and augment the existing hydrogeological structure knowledge of the aquifer systems in the Nara Basin.
Acknowledgement
This work is supported by the research grant of restoration and creation in a coastal environment in Osaka Bay area (PI: Mitsuyo Saito, No. 060003) and the JSPS Fund for the Promotion of Joint International Research (Fostering Joint International Research (A)) (PI: Mitsuyo Saito, No. 20KK0262)
Globally, groundwater is extensively utilised for domestic, industrial, and agricultural purposes across several agro-urban catchments, leading to the unsustainable exploitation of limited groundwater resources. This, in turn, results in significant environmental and socio-economic challenges, thereby necessitating the assessment of the interaction between surface and groundwater resources. Nara Basin, an intermontane basin, is characterised by persistent flooding and drought, attributable to its topography, leading to excessive reliance on groundwater resources for domestic and intensive rice paddy cultivation. However, in recent decades, there has been barely research on the groundwater conditions in the Nara Basin considering the significant development of agricultural activities and land-use changes.In this study, we evaluate the impacts of over-abstraction on groundwater flow dynamics resulting from anthropogenic activities in the Nara Basin using a three-dimensional groundwater modelling approach.
Methodology
The groundwater flow dynamics is being simulated using MODFLOW 6 particularly the streamflow routing package for the rivers, recharge, and multi-aquifer well package for groundwater abstraction, over a period of 10 years (2000 – 2009). For assessing the interaction between surface and groundwater the streamflow routing package is being adopted. Whereas the hydrostratigraphic units of the basin were created using the available borehole logs. The model calibration would be conducted utilising Independent Model Parameter Estimation and Uncertainty Analysis (PEST) coupled with spatially distributed observation wells in the Nara Basin. While RMSE (Root Mean Square Error) and R2 correlation metrics would be used to evaluate the model performance.
Results and Discussion.
A simulated groundwater flow pattern directed towards the centre of the basin is probable, considering the possibility of a high groundwater head in the northernmost and southernmost region with higher elevation, whereas a lower groundwater heads in the centre of the basin. However, there could be an alternation in this regional flow pattern due to anthropogenic influence particularly over abstraction of groundwater for water supply, and reduction in recharge due to land-use and climate changes. Furthermore, the occurrence of river leakages and seepages to and from the aquifer is likely at various sections of the river, and play a crucial role in evaluating the interactions between surface and groundwater within the basin.
The findings of this research would broaden the understanding of the groundwater flow dynamics on a catchment-based approach, river-aquifer interactions and augment the existing hydrogeological structure knowledge of the aquifer systems in the Nara Basin.
Acknowledgement
This work is supported by the research grant of restoration and creation in a coastal environment in Osaka Bay area (PI: Mitsuyo Saito, No. 060003) and the JSPS Fund for the Promotion of Joint International Research (Fostering Joint International Research (A)) (PI: Mitsuyo Saito, No. 20KK0262)