Dam reoperation as an adaptation strategy for shifting patterns of water supply and demand - A case study for the Xinánjiang-Fuchunjiang reservoir cascade, China

Vonk, Erwin (2013) Dam reoperation as an adaptation strategy for shifting patterns of water supply and demand - A case study for the Xinánjiang-Fuchunjiang reservoir cascade, China.

Abstract:Climate change, rapid economic developments and further growth of the human population are regarded as the major drivers of increasing water-related problems worldwide. The changing hydrological circumstances and water demand patterns pose a challenge to the management of water resources systems as these systems are designed to maintain a fragile balance between water supply and demand. With the projected changes, this balance is likely to be disrupted, ultimately requiring adaptation of the existing infrastructure. In many water resources systems reservoirs are the key element to ensure a stable water supply. Yet, since reservoirs can be characterized as rather inflexible types of infrastructure, one of the few options for adaptation is to adjust their operation. It is however unclear to which degree of water supply and demand changes this so called dam reoperation is still possible. The objective of this thesis is to determine whether reoperation of the Xin’anjiang- Fuchunjiang reservoir cascade (Hangzhou Region, China) is an effective adaptation strategy to mitigate potential impacts of climate change and regional socio-economic developments. We follow a scenario-based approach to explore the effects of various likely degrees of supply and demand changes for the future period between 2011 and 2040. The outcomes are compared to the control period 1971-2000. Population growth, increasing industrial production and changing land use are considered as driving forces for increasing water demand, while climate change is investigated as process influencing water supply. The scenario-wise changes in water supply and demand are used as forcing for the WEAP water allocation model, which is employed to simulate reservoir performance. This performance is measured using the Shortage Index (SI) as indicator for water shortages and the Mean Annual Energy Production (MAEP) for hydropower generation. The impact of climate change and socio-economic developments on the reservoir system is determined by simulating the performance of conventional operating rules for both the control period and each future scenario. We find a SI of 0.007 for the control period and values ranging from 0.05 to 0.92 for the investigated future scenarios. The largest annual deficit is 3.9 billion m3 (15% of the annual supply requirement), simulated in the high water stress scenario. Even though the increasing SI implies that more drought problems are likely in the future period, the deficits are still fairly small compared to what is generally regarded acceptable in the literature. Next to the increasing water shortages, simulation of the various scenarios shows a decrease between -12.8% and -16.3% for the MAEP. In a second step the water allocation model is interlinked with the NSGA-II metaheuristic algorithm in order to derive long-term multireservoir operating rules adapted to each scenario. Based on the optimization results, we conclude that for this case dam reoperation is an effective adaptation strategy to reduce the impact of changing patterns of water supply and demand. Compared to conventional operation, operating rules that are adapted to the forecasted changes can reduce the SI with approximately 72% while the MAEP shows an average increase of 5.4%. Due to the fact that the average inflow in all scenarios is lower than during the control period, adapted operating rules cannot completely restore the system performance to that of the control period. The performance gains for energy production are thus limited to avoiding unnecessary spills and maintaining an optimal head over the turbines.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
Link to this item:http://purl.utwente.nl/essays/63169
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