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[ACG42-P02] Impact of climate and land-use changes on the discharge and sediment transport of the Tokoro River Basin, Japan.
Keywords:Discharge, Sediment transport, Depopulation, Climate change, Land-use change
This study analyzed the individual and combined impacts of future climate and land-use changes on discharge and suspended sediment (SS) loads of the Tokoro River Basin; a river basin in northern Japan, where severe changes in climate and depopulation are expected to occur. For the future climate scenario, ensemble simulations under the Representative Concentration Pathway 8.5 scenario from 2077 to 2095 were used. We used historical maps to construct a future land-use scenario in which agricultural lands and urban areas were converted to wastelands and forests due to depopulation. The Soil and Water Assessment Tool (SWAT) model was used to simulate the discharge and SS loads for each scenario.
As a result, climate change decreased the average annual discharge and SS loads by 23% and 9% respectively. Land-use change had small impact for both discharge (+1.1%) and SS loads (+1.8%). The combined impact of climate and land-use changes decreased discharge by 23%, and also decreased sediment transport the most (–34%) among all three future scenarios.
Under the future climate scenario, the large increase in evapotranspiration due to a temperature rise resulted in a decrease in discharge. The sediment transport for this scenario was reduced by the decrease in discharge. Although land-use change had little impact on sediment transport, it had changed the sediment regime; due to the conversion of agricultural lands to wastelands, the sediment yield was largely reduced (–97%) in this scenario, accelerating sediment supply by channel erosion instead. Thus, when the impact of climate and land-use changes were combined, sediment transport decreased the most due to decreases in both discharge and sediment yield.
The results of this study provide important knowledge of the individual and combined effects of climate and land-use changes on water and sediment regimes, especially in a depopulating region.
The details of this study are described in the following paper:
Impact of climate and land-use changes on the water and sediment dynamics of the Tokoro River Basin, Japan.: Yuka MUTO, Keigo NODA, Yasuyuki MARUYA, Takeyoshi CHIBANA and Satoshi WATANABE, Environmental Advances, Vol. 7, 100153 (2022) doi: 10.1016/j.envadv.2021.100153
As a result, climate change decreased the average annual discharge and SS loads by 23% and 9% respectively. Land-use change had small impact for both discharge (+1.1%) and SS loads (+1.8%). The combined impact of climate and land-use changes decreased discharge by 23%, and also decreased sediment transport the most (–34%) among all three future scenarios.
Under the future climate scenario, the large increase in evapotranspiration due to a temperature rise resulted in a decrease in discharge. The sediment transport for this scenario was reduced by the decrease in discharge. Although land-use change had little impact on sediment transport, it had changed the sediment regime; due to the conversion of agricultural lands to wastelands, the sediment yield was largely reduced (–97%) in this scenario, accelerating sediment supply by channel erosion instead. Thus, when the impact of climate and land-use changes were combined, sediment transport decreased the most due to decreases in both discharge and sediment yield.
The results of this study provide important knowledge of the individual and combined effects of climate and land-use changes on water and sediment regimes, especially in a depopulating region.
The details of this study are described in the following paper:
Impact of climate and land-use changes on the water and sediment dynamics of the Tokoro River Basin, Japan.: Yuka MUTO, Keigo NODA, Yasuyuki MARUYA, Takeyoshi CHIBANA and Satoshi WATANABE, Environmental Advances, Vol. 7, 100153 (2022) doi: 10.1016/j.envadv.2021.100153