#water_stress_index
#water_connectivity
#inter_basin_transfer
#climate_change_impacts
In 2019, Kai Duan from Sun Yat-Sen University and co-authors analyzed the effects of inter-basin transfers ("regional water connectivity") on surface water supply stress in the contiguous US under climate change scenarios. They found climate change would increase the highly water stressed areas from 14% to 18% in the US, along with other results.
Overall, this is a standard analysis of the drivers of historical water stress and future water stress changes. The considered drivers include domestic, thermoelectric, and agriculture uses, and inter-basin transfer.
The methodology was of interest.
The simulation was performed at HUC-8 level for the contiguous US.
The basic water balance equation for each water shed was:
Total flow at the basin outlet = Inflow from upstream basin + Local generated flow + Water consumption* +/- inter-basin transfer
(* note: water consumption = water withdrawal - return flow)
The author noted that there are four types of basins: headwater basins that have no inflow, midstream basins with both inflow and outflow, terminus basins that have no outflow, and isolated basins.
The inter-basin transfer data were pulled from historical sources. Fig. 1b shows that the inter-basin transfer projects have been quite prevalent in the US.
The methods of projecting future streamflow involved designing future scenarios:
(1) domestic uses were calculated as per capita domestic use * future population. The per capita use is assumed to be constant.
(2) thermoelectric use was calculated as per kWh water consumption * future electricity generation. The future electricity generation was taken from the Annual Energy Outlook. The water consumption rates were interpolated from historical values.
(3) irrigation water use was calculated as function of irrigated area and irrigation efficiency. Climate and non-climate factors contribute to changes in irrigation water use.
To evaluate water stress, two indices were used:
(1) Local Water Stress, the ratio of water demand to local generated flow.
(2) Global Water Stress, the ratio of water demand to total flow.
https://www.sciencedirect.com/science/article/pii/S0022169419300290#s0010
