Multiobjective Analysis of Green-Blue Water Uses in a Highly Utilized Basin: Case Study of Pangani Basin, Africa

Kiptala, Jeremiah Kipkulei; Mul, Marloes; Mohamed, Yasir A.; Zaag, Pieter van der

doi:10.1061/(asce)wr.1943-5452.0000960

Cited by 7 publications

(7 citation statements)

References 43 publications

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“…The inclusion of nutrient elimination and GHG emissions in multicriteria optimization regimes and quantitative trade-off analyses would be a major step towards achieving sustainable dam construction across entire river basins. These methods to manage trade-offs have successfully have been applied to enable water availability or hydroelectricity generation, as well as to maintain flows for river ecosystems 187,188 . Such optimization regimes have also been applied to dam-removal scenarios in the Willamette River basin (Oregon, USA), where it was shown that removing 12 dams would hydrologically reconnect 52% of the basin while only eliminating 1.6% of the water-storage capacity and hydroelectricity production 189 .…”

Section: Future Perspectivesmentioning

confidence: 99%

River dam impacts on biogeochemical cycling

Maavara

Chen

Meter

et al. 2020

Nat Rev Earth Environ

477

190

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River damming has been practised for millennia, with the first dams built before 2000 BCE in the Egyptian empire 1. The number of dams increased steadily prior to the Second World War, but expanded rapidly thereafter, peaking in the 1960s and 1970s, with most construction in North America and Western Europe 2. A second surge in dam construction began in the early 2000s, with over 3,700 hydroelectric dams either planned or under construction worldwide during this construction boom 3 , each with a generating capacity of >1 megawatt (MW). Many of the new dams are being constructed in South America, Asia and the Balkans, largely driven by the need to expand energy production in growing economies 3,4. Indeed, by 2015, dammed reservoirs supplied around 30-40% of irrigation water globally 5,6 , and 16.6% of the world's electricity was generated by hydropower 7. Almost two-thirds of the world's long rivers (that is, those >1,000 km) are no longer free-flowing 8 and the current surge in dam construction-motivated by the 2016 Paris Agreement and the need for greater renewable energy generation-is expected to double river fragmentation by 2030 (ref. 9). Accordingly, freshwater ecosystems have been referred to as the 'biggest losers' of the Paris Agreement 10. Nutrients, such as carbon (C), nitrogen (N), phosphorus (P) and silicon (Si), are transported and transformed along the land-ocean aquatic continuum (LOAC), forming the basis for freshwater and, ultimately, marine food webs.

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Section: Future Perspectivesmentioning

confidence: 99%

River dam impacts on biogeochemical cycling

Maavara

Chen

Meter

et al. 2020

Nat Rev Earth Environ

477

190

View full text Add to dashboard Cite

show abstract

“…Multi-objective evolutionary algorithms (MOEAs) are one such tool for assessing the trade-offs between water users in a river basin. MOEAs use stochastic search tools to simultaneously find the Pareto approximate set across multiple objectives (Reed et al, 2013;Matrosov et al, 2015;Hurford et al, 2020;Zatarain Salazar et al, 2016;Kiptala et al, 2018). The Pareto approximate or non-dominated set of solutions are the suite of solutions for which increasing the water allocation to one user leads to a reduction in the benefit to others.…”

Section: Introductionmentioning

confidence: 99%

“…In many of the studies where MOEAs have been applied, the e-flow objective in the simulation component of the model either meets a minimum flow release (Zatarain Salazar et al, 2017;Gonzalez et al, 2021;Kiptala et al, 2018;Hurford et al, 2020) or minimizes the deviation of flow from the natural, unregulated flow regime . The former objective, minimum flow releases, fails to thoroughly capture the essence of e-flows which are the "quantity, timing, and quality of freshwater flows and levels required to sustain aquatic ecosystems" (The Brisbane Declaration and Global Action Agenda on Environmental Flows, 2018, cited in Arthington et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the trade-offs in re-operating dams for the environment in the Lower Volta River

Owusu

Salazar

Mul

et al. 2023

Hydrol. Earth Syst. Sci.

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Abstract. The construction of the Akosombo and Kpong dams in the Lower Volta River basin in Ghana changed the downstream riverine ecosystem and affected the lives of downstream communities, particularly those who lost their traditional livelihoods. In contrast to the costs borne by those in the vicinity of the river, Ghana has enjoyed vast economic benefits from the affordable hydropower, irrigation schemes and lake tourism that developed after construction of the dams. Herein lies the challenge; there exists a trade-off between water for river ecosystems and related services on the one hand and anthropogenic water demands such as hydropower or irrigation on the other. In this study, an Evolutionary Multi-Objective Direct Policy Search (EMODPS) is used to explore the multi-sectoral trade-offs that exist in the Lower Volta River basin. Three environmental flows, previously determined for the Lower Volta, are incorporated separately as environmental objectives. The results highlight the dominance of hydropower production in the Lower Volta but show that there is room for providing environmental flows under current climatic and water use conditions if the firm energy requirement from Akosombo Dam reduces by 12 % to 38 % depending on the environmental flow regime that is implemented. There is uncertainty in climate change effects on runoff in this region; however multiple scenarios are investigated. It is found that climate change leading to increased annual inflows to the Akosombo Dam reduces the trade-off between hydropower and the environment as this scenario makes more water available for users. Furthermore, climate change resulting in decreased annual inflows provides the opportunity to strategically provide dry-season environmental flows, that is, reduce flows sufficiently to meet low flow requirements for key ecosystem services such as the clam fishery. This study not only highlights the challenges in balancing anthropogenic water demands and environmental considerations in managing existing dams but also identifies opportunities for compromise in the Lower Volta River.

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“…The Pareto approximate or nondominated set of solutions are the suite of solutions for which increasing the water allocation to one user leads to a reduction in the benefit to others. EMODPS uses multi-objective evolutionary algorithms (MOEAs), stochastic search tools to simultaneously find the Pareto approximate set across multiple objectives (Reed et al, 2013;Matrosov et al, 2015;Zatarain Salazar et al, 2016;Kiptala et al, 2018;Hurford et al, 2020). The advantage of MOEAs is that they do not require pre-specifying preferences across objectives, thereby supporting unbiased a posteriori decision making (Reed et al, 2013;.…”

Section: Introductionmentioning

confidence: 99%

“…In many of the studies where MOEAs have been applied, the e-flow objective in the simulation component of the model either meets a minimum flow release (Zatarain Salazar et al, 2017;Kiptala et al, 2018;Hurford et al, 2020;Gonzalez et al, 2021) or minimizes the deviation of flow from the natural, unregulated flow regime . The former objective, minimum flow releases, fails to thoroughly capture the essence of e-flows which are the "quantity, timing, and quality of freshwater flows and levels required to sustain aquatic ecosystems" (Brisbane Declaration, 2018).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the trade-offs in re-operating dams for the environment in the Lower Volta River

Owusu

Salazar

Mul

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The construction of the Akosombo and Kpong dams in the Lower Volta River Basin in Ghana changed the downstream riverine ecosystem and affected the lives of downstream communities, particularly those who lost their traditional livelihoods. In contrast to the costs borne by those in the vicinity of the river, Ghana as a whole, has enjoyed vast economic benefits from the affordable hydropower, irrigation schemes and lake tourism that developed after construction of the dams. Herein lies the challenge; there exists a trade-off between water for river ecosystems and related services on the one hand, and anthropogenic water demands such hydropower or irrigation on the other. In this study, an Evolutionary Multi-Objective Direct Policy Search (EMODPS) is used to identify the multi-sectorial trade-offs that exist in the Lower Volta River Basin. Three environmental flows, previously determined for the Lower Volta are incorporated separately as an environmental objective. The results highlight the dominance of hydropower production in the Lower Volta, but show that there is room for providing environmental flows under current climatic and water use conditions if firm energy requirement from Akosombo Dam reduces by 12 % to 38 % depending on the environmental flow regime that is implemented. There is uncertainty in climate change effects on runoff in this region, however multiple scenarios are investigated. It is found that climate change leading to increased annual inflows to the Akosombo Dam reduces the trade-off between hydropower and the environment while climate change resulting in lower inflows provide the opportunity to strategically provide dry season environmental flows, that is, reduce flows sufficiently to meet low flow requirements for key ecosystem services such as the clam fishery. This study not only highlights the challenges in balancing anthropogenic water demands and environmental considerations in managing existing dams, but also identifies opportunities for compromise in the Lower Volta River.

show abstract

Multiobjective Analysis of Green-Blue Water Uses in a Highly Utilized Basin: Case Study of Pangani Basin, Africa

Cited by 7 publications

References 43 publications

River dam impacts on biogeochemical cycling

River dam impacts on biogeochemical cycling

Quantifying the trade-offs in re-operating dams for the environment in the Lower Volta River

Quantifying the trade-offs in re-operating dams for the environment in the Lower Volta River

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