Abstract
Freshwater resources are limited and seasonally and spatially unevenly distributed. Thus, in water resources management plans, storage reservoirs play a vital role in safeguarding drinking, irrigation, hydropower and livestock water supply. In the last decades, the dams’ negative effects, such as fragmentation of water flow and sediment transport, are considered in decision-making, for achieving an optimal balance between human needs and healthy riverine and coastal ecosystems. Currently, operation of existing reservoirs is challenged by increasing water demand, climate change effects and active storage reduction due to sediment deposition, jeopardizing their supply capacity. This paper proposes a methodological framework to reassess supply capacity and management resilience for an existing reservoir under these challenges. Future projections are derived by plausible climate scenarios and global climate models and by stochastic simulation of historic data. An alternative basic reservoir management scenario with a very low exceedance probability is derived. Excess water volumes are investigated under a probabilistic prism for enabling multiple-purpose water demands. Finally, this method is showcased to the Ladhon Reservoir (Greece). The probable total benefit from water allocated to the various water uses is estimated to assist decision makers in examining the tradeoffs between the probable additional benefit and risk of exceedance.
Highlights
Under the rising pressures of increasing water demand along with climate change effects, i.e., changes in water distribution and reduced water availability and quality extremes, a key challenge in water resources management is the adaptation of the water storage capacity to strengthen water security [1,2]
We propose the following steps for a general methodological process in order to reassess and adapt the existing reservoir operation and management under these challenges: 1. Identify: (i) the current and potential water uses, (ii) the monthly water demand time series and (iii) periods of possible conflicts among the water uses related to the reservoir water management
Through the comparison of the simulated historic and future monthly runoff into the Ladhon Reservoir, it is worth noticing that: (i) For the optimistic Intergovernmental Panel on Climate Change (IPCC) climatic scenario, representative concentration pathways (RCPs) 2.6, in the near future (2050) the runoff was mainly reduced from October until March up to 25%, and a small increase up to 5% is noticed for the spring and summer period, which is in accordance with the scenario assumptions
Summary
Under the rising pressures of increasing water demand along with climate change effects, i.e., changes in water distribution and reduced water availability and quality extremes, a key challenge in water resources management is the adaptation of the water storage capacity to strengthen water security [1,2]. Predicting the future is difficult if not impossible, and hydrologic planning will always consider probabilistic or multiple plausible realizations and adopt adaptive risk management with systems planned for particular levels of security or reliability [22] Considering their strengths and weaknesses, we consider both possibilities (i.e., by using plausible climate scenarios and global climate models (GCMs) or by extrapolation of historic data) in order to incorporate the uncertainty of runoff change. The present paper aims: (i) to propose a methodological framework for the reassessment of the present reservoir management strategy under future hydrologic conditions and the reduction of active storage due to sediment deposition and (ii) to examine, under a probabilistic prism, possible alterations of the reservoir management by proposing the use of additional excess water volumes enabling multiple-purpose water demands. Application; in Section 4, the results and discussion are presented; in Section 5, conclusions are drawn
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