Building Regional Water-Use Scenarios Consistent with Global Shared Socioeconomic Pathways

Mingtian Yao,Saskia E Werners,Pavel Kabat,Sylvia Tramberend,Ronald W.A Hutjes

doi:10.1007/s40710-016-0203-x

Abstract

Water use projections are crucial to safeguard sustainable access to freshwater in the future. The Water Futures and Solution initiative (WFaS) has developed a set of global water-use scenarios consistent with the recent Assessment Report framework of the Intergovernmental Panel on Climate Change, notably the Shared Socioeconomic Pathways (SSPs), and applying a hydro-economic classification that links a socioeconomic dimension with hydrologic complexity. Here we present regional water use projections for the Pearl River Delta (PRD) in China consistent with the WFaS global assessment. Using two different downscaling techniques for developing regional water-use scenarios based on the national assumptions made for China in the WFaS assessment, we investigate PRD’s water-use projections. The findings indicate significant differences in the PRD’s regional development trends compared to China’s national SSP. The regionalized scenarios project lower water use because of the PRD’s lower share of the manufacturing sector in total Gross Domestic Product (GDP) and higher rates of technological improvement, compared to national development trend assumptions. Nevertheless, hydrological challenges remain for the PRD. Its total water use would still increase by up to 54% in 2030 under the regionalized scenarios. Although uncertainties related to scarce data remain, we provide a scientifically sound and feasible method to generate regional scenarios that can capture the regional sectorial water uses development as well as being consistent with national water-use scenarios developed by global assessment.

Highlights

Population growth and socio-economic developments have fundamentally changed the drivers of freshwater use by humans (Hoekstra and Chapagain 2007)
The term BSSP scenarios^ refers to the Shared Socioeconomic Pathways (SSPs)-CN and SSP-Pearl River Delta (PRD) scenarios developed for the present study, rather than the original SSP scenario descriptions (O’Neill et al 2015)
The two scenario families SSP5 projects the largest contribution of 81% (SSP-CN) and SSP-PRD illustrate two different downscaling techniques to link the national assumptions for China—developed and applied in the global assessment—with the regional scale of the PRD

Summary

Introduction

Population growth and socio-economic developments have fundamentally changed the drivers of freshwater use by humans (Hoekstra and Chapagain 2007). The growing water use is approaching total renewable freshwater availability in many regions, and as a result, freshwater is becoming one of the most limited resources (Wiek and Larson 2012) For future management, both water availability and water-use projections are required to safeguard sustainable access to freshwater to sustain livelihoods, well-being, and socio-economic development (Pahl-Wostl 2007; UN-Water 2013). SSPs and RCPs were independently developed in the context of the Intergovernmental Panel on Climate Change (IPCC) Assessment Report framework (Moss et al 2010; van Vuuren et al 2014). The WFaS developed a set of water-use scenarios consistent with the SSPs and RCPs, and estimated the global sectorial water use using a state-of-the-art multi-model framework (Wada et al 2016) Note that water use does not refer to Bwater consumption^, defined as water withdrawal minus return to the river system after usage, e.g. for cooling, irrigation)

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