Multi-Objective Optimization for Analysis of Changing Trade-Offs in the Nepalese Water–Energy–Food Nexus with Hydropower Development

Sanita Dhaubanjar,Peter Bauer-Gottwein,Claus Davidsen

doi:10.3390/w9030162

Sanita Dhaubanjar, Peter Bauer-Gottwein + Show 1 more

Open Access

https://doi.org/10.3390/w9030162

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Journal: Water	Publication Date: Feb 24, 2017
Citations: 47	License type: CC BY 4.0

Affiliation: Technical University of Denmark

Abstract

While the water–energy–food nexus approach is becoming increasingly important for more efficient resource utilization and economic development, limited quantitative tools are available to incorporate the approach in decision-making. We propose a spatially explicit framework that couples two well-established water and power system models to develop a decision support tool combining multiple nexus objectives in a linear objective function. To demonstrate our framework, we compare eight Nepalese power development scenarios based on five nexus objectives: minimization of power deficit, maintenance of water availability for irrigation to support food self-sufficiency, reduction in flood risk, maintenance of environmental flows, and maximization of power export. The deterministic multi-objective optimization model is spatially resolved to enable realistic representation of the nexus linkages and accounts for power transmission constraints using an optimal power flow approach. Basin inflows, hydropower plant specifications, reservoir characteristics, reservoir rules, irrigation water demand, environmental flow requirements, power demand, and transmission line properties are provided as model inputs. The trade-offs and synergies among these objectives were visualized for each scenario under multiple environmental flow and power demand requirements. Spatially disaggregated model outputs allowed for the comparison of scenarios not only based on fulfillment of nexus objectives but also scenario compatibility with existing infrastructure, supporting the identification of projects that enhance overall system efficiency. Though the model is applied to the Nepalese nexus from a power development perspective here, it can be extended and adapted for other problems.

Highlights

A lack of cross-sector coordination is hampering efficient resource utilization in many developing countries like Nepal [1,2,3,4]
Using the context of the Nepalese hydropower development, this study demonstrates a novel coupling of a linear water resources model [20] and a direct current (DC) load flow based optimal power flow (OFP) model [46] with fine spatial discretization to realistically model tradeoffs and synergies in the water–energy–food nexus
Since scenario A) excludes some seasonal plants that only operate during the high flow season, it is reasonable that the deviation between simulated and actual production is higher in the wet period (May–October) than in the dry period (November–April)

Summary

Introduction

A lack of cross-sector coordination is hampering efficient resource utilization in many developing countries like Nepal [1,2,3,4]. Despite the abundance of water resources in Nepal, poor governance and inequitable access can worsen water scarcity if the current pressures of export-oriented hydropower development persist [5]. In such a context, the water–energy–food nexus approach can help us understand cross-sector trade-offs and identify coordinated development pathways that synchronize sectorial benefits [1,2,6,7]. For the specific context of Nepalese hydropower development, Gyawali [10] demonstrate that the nexus approach can fuel a conscious development of multi- instead of single-purpose water infrastructures

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