In a changing climate and society, water systems operation can play a key role for securing water, energy, and food, and rebalancing their cross-dependencies across a range of time scales. Traditional management strategies are designed assuming that the statistical characteristics of future inflows and water demands will be similar to those of the historical record. This assumption is no longer valid due to the large degree of uncertainty about the future conditions, potentially causing declines in water resource system performance or even complete system failure. This is especially true for river basins with high intra-annual and inter-annual variability, such as monsoonal systems, that need to buffer against seasonal droughts and protect against extreme floods by timely adapting to changing timing, intensity, duration, and frequency of hydrologic extremes. This study contributes an innovative method for exploring how possible modifications of the monsoonal cycle, induced by the changing climate, impact the robustness of reservoir operating policies designed assuming stationary hydrologic and socioeconomic conditions. We illustrate this analysis on the Red River basin in Vietnam, where reservoirs and dams serve as important sources of hydropower production, multisectoral water supply, and flood protection for the capital city of Hanoi. Building on recent bottom-up approaches based on exploratory modeling techniques, we first synthetically generate climate exposures for a range of plausible changes that extend beyond the bounds projected by General Circulation Models (GCMs), and assess the associated system response along with the existence of critical thresholds for system failure. Then, we evaluate the plausibility of the generated inflow scenarios by driving a hydrological model with bias-corrected climate projections from 34 GCMs in the CMIP5 multimodel ensemble, each run with multiple initial conditions across all four representative concentration pathways. Our results show that reservoir operations designed assuming stationarity provide robust hydropower performance in the Red River basin. However, increased mean streamflow, amplification of the within-year monsoonal cycle, and increased interannual variability all threaten their ability to manage flood risk and meet multisectoral water demands, exacerbating multisector trade-offs.

Coping with changing climate extremes in large regulated river basins

A. Castelletti;M. Giuliani;
2020

Abstract

In a changing climate and society, water systems operation can play a key role for securing water, energy, and food, and rebalancing their cross-dependencies across a range of time scales. Traditional management strategies are designed assuming that the statistical characteristics of future inflows and water demands will be similar to those of the historical record. This assumption is no longer valid due to the large degree of uncertainty about the future conditions, potentially causing declines in water resource system performance or even complete system failure. This is especially true for river basins with high intra-annual and inter-annual variability, such as monsoonal systems, that need to buffer against seasonal droughts and protect against extreme floods by timely adapting to changing timing, intensity, duration, and frequency of hydrologic extremes. This study contributes an innovative method for exploring how possible modifications of the monsoonal cycle, induced by the changing climate, impact the robustness of reservoir operating policies designed assuming stationary hydrologic and socioeconomic conditions. We illustrate this analysis on the Red River basin in Vietnam, where reservoirs and dams serve as important sources of hydropower production, multisectoral water supply, and flood protection for the capital city of Hanoi. Building on recent bottom-up approaches based on exploratory modeling techniques, we first synthetically generate climate exposures for a range of plausible changes that extend beyond the bounds projected by General Circulation Models (GCMs), and assess the associated system response along with the existence of critical thresholds for system failure. Then, we evaluate the plausibility of the generated inflow scenarios by driving a hydrological model with bias-corrected climate projections from 34 GCMs in the CMIP5 multimodel ensemble, each run with multiple initial conditions across all four representative concentration pathways. Our results show that reservoir operations designed assuming stationarity provide robust hydropower performance in the Red River basin. However, increased mean streamflow, amplification of the within-year monsoonal cycle, and increased interannual variability all threaten their ability to manage flood risk and meet multisectoral water demands, exacerbating multisector trade-offs.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1209032
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