Preprints
https://doi.org/10.5194/hess-2021-40
https://doi.org/10.5194/hess-2021-40

  26 Jan 2021

26 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal HESS.

Disentangling Sources of Future Uncertainties for Water Management in Sub-Saharan River Basins

Alessandro Amaranto1, Dinis Juizo2, and Andrea Castelletti3,1 Alessandro Amaranto et al.
  • 1Department of Electronics, Informations and Bioengineering, Politecnico di Milano, Piazza Leonardi da Vinci, Milano, Italy
  • 2Department of Civil Engineering, Eduardo Mondlane University, Maputo, Mozambique
  • 3Institute of Environmental Engineering, ETH Zurich, Zurich, Switzerland

Abstract. Water management in sub-Saharan African river basins is challenged by uncertain future climatic, social and economical patterns, potentially causing diverging water demands and availability, as well as by multi-stakeholder dynamics, resulting in evolving conflicts and tradeoffs. In such contexts, a better understanding of the sensitivity of water management to the different sources of uncertainty can support policy makers in identifying robust water supply policies balancing optimality and low vulnerability against likely adverse future conditions. This paper contributes an integrated decision-analytic framework combining optimization, robustness, sensitivity and uncertainty analysis to retrieve the main sources of vulnerability to optimal and robust reservoir operating policies across multi-dimensional objective spaces. We demonstrate our approach onto the lower Umbeluzi river basin, Mozambique, an archetypal example of sub-Saharan river basin, where surface water scarcity compounded by substantial climatic variability, uncontrolled urbanization rate, and agricultural expansion are hampering the Pequenos Lipompos dam ability of supplying the agricultural, energy and urban sectors. We adopt an Evolutionary Multi-Objective Direct Policy Search optimization approach for designing optimal operating policies, whose robustness against social, agricultural, infrastructural and climatic uncertainties is assessed via robustness analysis. We then implement the GLUE and PAWN uncertainty and sensitivity analysis methods for disentangling the main challenges to the sustainability of the operating policies and quantifying their impacts on the urban, agricultural and energy sectors. Numerical results highlight the importance of robustness analysis when dealing with uncertain scenarios, with optimal-non robust reservoir operating policies largely dominated by robust control strategies across all stakeholders. Furthermore, while robust policies are usually vulnerable only to hydrological perturbations and are able to sustain the majority of population growth and agricultural expansion scenarios, non-robust policies are sensitive also to social and agricultural changes, and require structural interventions to ensure stable supply.

Alessandro Amaranto et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-40 - Disentangling Sources of Future Uncertainties forWater Management in Sub-Saharan River Basins by Amaranto et al.', Alessio Ciullo, 22 Mar 2021
    • AC1: 'Reply on RC1', Andrea Castelletti, 05 May 2021
  • RC2: 'Comment on hess-2021-40', Anonymous Referee #2, 19 Apr 2021
    • AC2: 'Reply on RC2', Andrea Castelletti, 05 May 2021
  • EC1: 'Editor's comment', Dimitri Solomatine, 21 May 2021

Alessandro Amaranto et al.

Alessandro Amaranto et al.

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