Infrastructure sufficiency in meeting water demand under climate-induced socio-hydrological transition in the urbanizing Capibaribe River basin – Brazil

A Ribeiro Neto,J A Cirilo,S M G L Montenegro,C A Scott,E A Lima

doi:10.5194/hess-18-3449-2014

Abstract

Abstract. Water availability for a range of human uses will increasingly be affected by climate change, especially in the arid and semiarid tropics. The main objective of this study is to evaluate the infrastructure sufficiency in meeting water demand under climate-induced socio-hydrological transition in the Capibaribe River basin (CRB). The basin has experienced spatial and sectoral (agriculture-to-urban) reconfiguration of water demands. Human settlements that were once dispersed, relying on intermittent sources of surface water, are now larger and more spatially concentrated, which increases water-scarcity effects. Based on the application of linked hydrologic and water-resources models using precipitation and temperature projections of the IPCC SRES (Special Report: Emissions Scenarios) A1B scenario, a reduction in rainfall of 26.0% translated to streamflow reduction of 60.0%. We used simulations from four members of the HadCM3 (UK Met Office Hadley Centre) perturbed physics ensemble, in which a single model structure is used and perturbations are introduced to the physical parameterization schemes in the model (Chou et al., 2012). We considered that the change of the water availability in the basin in the future scenarios must drive the water management and the development of adaptation strategies that will manage the water demand. Several adaptive responses are considered, including water-loss reductions, wastewater collection and reuse, and rainwater collection cisterns, which together have potential to reduce future water demand by 23.0%. This study demonstrates the vulnerabilities of the infrastructure system during socio-hydrological transition in response to hydroclimatic and demand variabilities in the CRB and also indicates the differential spatial impacts and vulnerability of multiple uses of water to changes over time. The simulations showed that the measures proposed and the water from interbasin transfer project of the São Francisco River had a positive impact over the water supply in the basin, mainly for human use. Industry and irrigation will suffer impact unless other measures are implemented for demand control.

Highlights

IntroductionManaging the transition can entail the use of scenarios to deal with uncertainties, generating and sustaining societal pressure in political and market terms in order to safeguard the long-term orientation and goals of the transition process (Loorbach and Rotmans, 2010)
We address the concept of infrastructure sufficiency as the ability of water supply systems to reliably meet future demands given the uncertainty inherent in future supply-and-demand conditions
The understanding of socio-hydrology that we advance in this paper is a sequential and coevolutionary process of (a) human demand for water exceeding natural supply; (b) development of local-scale, low-cost infrastructure to enhance and stabilize supply; (c) demand growth based on supply enhancement; (d) recurring water scarcity and/or short-term supply insufficiency; and (e) infrastructure to capture extra-local sources of supply

Summary

Introduction

Managing the transition can entail the use of scenarios to deal with uncertainties, generating and sustaining societal pressure in political and market terms in order to safeguard the long-term orientation and goals of the transition process (Loorbach and Rotmans, 2010) To pursue this conceptual approach, a central question we intend to answer in this paper is, “can models and scenarios aid in evaluating infrastructure and its sufficiency, augmented by alternative strategies to manage socio-hydrological transition in a semiarid basin?”. Small communities are increasingly concentrating around infrastructural water supplies (groundwater, where available, but increasingly tanker-truck supplies during drier months and overextended drought periods) Together these constitute a socio-hydrological transition process that results from (a) hydroclimatic variability, (b) investment and assistance programs that may enhance but can supplant local adaptive capacity, and (c) demographic trends that are already pronounced in Brazil

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Conclusion