Stochastic dual dynamic programming (SDDP) is one of the few algorithmic solutions available to optimize large-scale water resources systems while explicitly considering uncertainty. This paper explores the consequences of, and proposes a solution to, the existence of multiple near-optimal solutions (MNOS) when using SDDP for mid- or long-term river basin management. These issues arise when the optimization problem cannot be properly parametrized due to poorly defined and/or unavailable data sets. This work shows that when MNOS exists, 1) SDDP explores more than one solution trajectory in the same run, suggesting different decisions in distinct simulation years even for the same point in the state-space, and 2) SDDP is shown to be very sensitive to even minimal variations of the problem setting, e.g. initial conditions — we call this “algorithmic chaos”.
The current literature mainly describes what is meant by the term benefit sharing in the the context of transboundary river basins and discusses this from a conceptual point of view, but falls short of providing practical, institutional arrangements that ensure maximum economic welfare as well as collaboratively developed methods for encouraging the equitable sharing of benefits. In this study we define an institutional arrangement that distributes welfare in a river basin by maximizing the economic benefits of water use and then sharing these benefits in an equitable manner using a method developed through stakeholder involvement.We describe a methodology in which (i) a hydrological model is used to allocate scarce water resources, in an economically efficient manner, to water users in a transboundary basin, (ii) water users are obliged to pay for water, and (iii) the total of these water charges are equitably redistributed as monetary compensation to users in an amount determined through the application of a sharing method developed by stakeholder input, thus based on a stakeholder vision of fairness, using an axiomatic approach. The whole system is overseen by a river basin authority. The methodology is applied to the Eastern Nile River basin as a case study. The described technique not only ensures economic efficiency, but may also lead to more equitable solutions in the sharing of benefits in transboundary river basins because the definition of the sharing rule is not in question, as would be the case if existing methods, such as game theory, were applied, with their inherent definitions of fairness.
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In many cases, water allocation is linked to the energy sector through hydropower. In this study, the water value method was used to simulate reservoir operations in an international basin under different assumptions about national priorities and regional energy cooperation. Benefits in the water sector and the power sector were compared considering both cooperative and noncooperative behavior by national players. The approach is demonstrated for a semiarid international river basin characterized by conflict between upstream hydropower production and downstream irrigated agriculture. A scenario assuming regional cooperation in the power sector came closest to the multisectoral basin cooperation benchmark and produced fewer national costs than scenarios assuming noncooperative behavior.
Results that exhibit such sensitivity are difficult to interpret. This work proposes a re-optimization method, which simulates system decisions by periodically applying cuts from one given year from the SDDP run. Simulation results obtained through this re-optimization approach are steady-state solutions, meaning that their probability distributions are stable from year to year. A water resource modeling process is demonstrated to support multistakeholder negotiations over transboundary management of the Nile River.
This endeavor is controversially debated in the public and the scientific literature. Contributing to this discussion, by shading some light on climate change issues, an eco-hydrological model, equipped with a reservoir module, was applied to investigate downstream hydrological impacts during filling and regular operation, the latter considering climate change projected by an ensemble of 10 global and regional climate models. Our results show that at the earliest after 20 months, the dam could produce hydroelectric power.
Wednesday, September 27, 2006
Almost independently of the operation rules, the highly variable discharge regime will be significantly altered to a regime with almost equal flows each month. Achieving a win-win situation for all riparian countries requires a high level of cooperation in managing the Eastern Nile water resources.
Managing the basinâ€™s water resources is complex because of its trans-boundary nature, exacerbated by environmental degradation and strong climate variability. The Nile basin water resources have been extensively studied during the last 125 years for planning and management purposes, in particular with regard to the use of blue water in the downstream part of the basin, though recently some studies have also focused on the upper parts.
In the economic sector of the H-E model, Regional Positive Mathematical Programming (RPMP) was used to study the effects of various scenarios (marketing network reform policies) on crop patterns. In the hydrologic sector of the H-E model, WEAP was used to analyze and simulate of water resources according to the different crop patterns (results obtained from economic sector). The results showed the network marketing reform leads to change in cropping pattern. The cultivated area of crops with high marketing margin was increased. Also, the cultivated area of alfalfa and cotton decreased in most scenarios.
The paper ends with suggestions on how to deal with open questions and lessons learned from the ongoing NBI process. Since 1999 a multilateral effort termed the Nile Basin Initiative has been underway among the Nile riparians to explore opportunities for maximizing the benefits of the river’s waters through cooperative development and management of the basin. However, to date there has been virtually no explicit discussion of the economic value of cooperative water resources development.
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Norplan, Norconsult and Lahmeyer International, Karadobi Multipurpose Projet pre-feasibility study (Final Report) – vol. 5, Initial Environmental Assessment, Technical Report, Ministry of Water Resources, The Federal Democratic Republic of Ethiopia, 2006. reapplied this framework specifically considering the GERD, showing strong economic benefits of cooperation. Similar to the studies mentioned previously, this framework assumes optimized reservoir management across the international borders, which effectively replaces existing management with an ideally coordinated system.
Electrical Engineer Julio Hildebrand is part of the Lahmeyer team advising Sudanese Hydro Generation Company Ltd (SHGC) on the damâ€™s rehabilitation and uprating. Discover the project from Julioâ€™s perspective. Planning in the Blue Nile, Discussion Paper Series 13-05, Environment for Development, 2013. used a stochastic dual dynamic programming approach within a hydro-economic framework to optimize operations for the benefits of hydropower and agriculture pro- duction under various build-out scenarios.