Editing IPCC:AR6/SR15/Chapter-4 (section)

==== 4.3.3.8 Sustainable urban water and environmental services ====

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Urban water supply and wastewater treatment is energy intensive and currently accounts for significant GHG emissions (Nair et al., 2014) <sup>[[#fn:r401|401]]</sup> . Cities can integrate sustainable water resource management and the supply of water services in ways that support mitigation, adaptation and development through waste water recycling and storm water diversion (Xue et al., 2015; Poff et al., 2016) <sup>[[#fn:r402|402]]</sup> . Governance and finance challenges complicate balancing sustainable water supply and rising urban demand, particularly in low-income cities (Bettini et al., 2015; Deng and Zhao, 2015; Hill Clarvis and Engle, 2015; Lemos, 2015; Margerum and Robinson, 2015) <sup>[[#fn:r403|403]]</sup> .

Urban surface-sealing with impervious materials affects the volume and velocity of runoff and flooding during intense rainfall (Skougaard Kaspersen et al., 2015) <sup>[[#fn:r404|404]]</sup> , but urban design in many cities now seeks to mediate runoff, encourage groundwater recharge and enhance water quality (Liu et al., 2014; Lamond et al., 2015; Voskamp and Van de Ven, 2015; Costa et al., 2016; Mguni et al., 2016; Xie et al., 2017) <sup>[[#fn:r405|405]]</sup> . Challenges remain for managing intense rainfall events that are reported to be increasing in frequency and intensity in some locations (Ziervogel et al., 2016b) <sup>[[#fn:r406|406]]</sup> , and urban flooding is expected to increase at 1.5°C of warming (Alfieri et al., 2017) <sup>[[#fn:r407|407]]</sup> . This risk falls disproportionately on women and poor people in cities (Mitlin, 2005; Chu et al., 2016; Ziervogel et al., 2016b; Chant et al., 2017; Dodman et al., 2017a, b) <sup>[[#fn:r408|408]]</sup> .

Nexus approaches that highlight urban areas as socio-ecological systems can support policy coherence (Rasul and Sharma, 2016) <sup>[[#fn:r409|409]]</sup> and sustainable urban livelihoods (Biggs et al., 2015) <sup>[[#fn:r410|410]]</sup> . The water–energy–food (WEF) nexus is especially important to growing urban populations (Tacoli et al., 2013; Lwasa et al., 2014; Villarroel Walker et al., 2014) <sup>[[#fn:r411|411]]</sup> .

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