2:00 PM - 2:15 PM
[AHW24-14] Impact of the groundwater in the Kanogawa riverine system: Numerical modeling bridging hydrogeological and ecological systems from the headwaters to the estuary of the Kanogawa River
Keywords:Kanogawa River Spillway, Hyporheic Zone, Ecosystem, Simulation, HydroGeoSphere
To understand the relationship between aquatic water flow regimes and ecosystems along streams, it is required to understand the hyporheic zone (HZ), where the interaction of surface water and groundwater being coupled in flow, sediments transport, and biogeochemical reactions occur, over a wide range of spatial and temporal scales.
From the headwaters to the estuary of the Kanogawa River, we applied an integrated watershed modeling technique to analyze spatio-temporal distribution changes in the flow data, being available for the input data in ecosystem response. Specifically, a three-dimensional numerical simulation focusing on surface and groundwater exchange fluxes (HEF) were conducted to investigate the flow regime alteration caused by the Kanogawa River spillway. Also, we discussed the relationship between the computed hydrogeological quantities and the estimated ecosystem response driven by the changes induced in the structure of riverbed and banks for different rainfall events in intensity. The HydroGeoSphere (HGS) simulator was employed both for the river-channel scale and the watershed-scale modeling.
For the river-channel scale, a numerical simulation model was constructed around the Kanogawa River spillway and its vicinity, incorporating detailed topographic features of the riverbed and banks, and hydrogeological structures. We visualized the spatial distribution of discharge and recharge areas based on the modeling of the spatio-temporal changes in HEF against different rainfall events. For the watershed-scale, an integrated watershed modeling was conducted covering the entire Kanogawa River basin from the headwaters to the estuary. The validity of the model was verified by reproducing the river discharge measurements.
The result of the current simulation suggests that the Kanogawa River basin are characterized differently by the hydrogeological features in the upstream, midstream and downstream areas. In the coming stage of this study, upscaling techniques to relate the computed HEF by the channel scale model to the watershed scale model is to be investigated.
This study was supported by the River Works Technology Research and Development Program from Ministry of Land, Infrastructure, Transport and Tourism.
From the headwaters to the estuary of the Kanogawa River, we applied an integrated watershed modeling technique to analyze spatio-temporal distribution changes in the flow data, being available for the input data in ecosystem response. Specifically, a three-dimensional numerical simulation focusing on surface and groundwater exchange fluxes (HEF) were conducted to investigate the flow regime alteration caused by the Kanogawa River spillway. Also, we discussed the relationship between the computed hydrogeological quantities and the estimated ecosystem response driven by the changes induced in the structure of riverbed and banks for different rainfall events in intensity. The HydroGeoSphere (HGS) simulator was employed both for the river-channel scale and the watershed-scale modeling.
For the river-channel scale, a numerical simulation model was constructed around the Kanogawa River spillway and its vicinity, incorporating detailed topographic features of the riverbed and banks, and hydrogeological structures. We visualized the spatial distribution of discharge and recharge areas based on the modeling of the spatio-temporal changes in HEF against different rainfall events. For the watershed-scale, an integrated watershed modeling was conducted covering the entire Kanogawa River basin from the headwaters to the estuary. The validity of the model was verified by reproducing the river discharge measurements.
The result of the current simulation suggests that the Kanogawa River basin are characterized differently by the hydrogeological features in the upstream, midstream and downstream areas. In the coming stage of this study, upscaling techniques to relate the computed HEF by the channel scale model to the watershed scale model is to be investigated.
This study was supported by the River Works Technology Research and Development Program from Ministry of Land, Infrastructure, Transport and Tourism.