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Assessing climate change adaptations for community-scale water resources using a low-frequency weather generator

Li, Yuan-Hua, Tung, Ching-Pin, Li, Yuan-Hung, Chen, Pei-Yuan
Paddy and water environment 2018 v.16 no.1 pp. 55-69
General Circulation Models, climate, climate change, constructed wetlands, irrigation water, meteorological data, paddies, rain, supply balance, water harvesting, water supply, water use efficiency
Water adaptation strategies are necessary for decreasing climate change impacts on local societies. This study models a community water supply system as a distributed adaptation measure for decreasing the loading of the centralized water supply system. The modeled community water supply system addresses both supply and demand at the community scale using constructed wetlands, rainwater harvesting systems, household storage, and paddy fields. The purpose of this study was to evaluate a community water supply system in various climate change scenarios using three performance indicators: water saving efficiency (WSE), tolerance duration (TD), and water use efficiency (WUE). A low-frequency weather generator (LF-WGEN) was proposed and used to produce future weather data for evaluating the impacts of climate change. LF-WGEN generates future weather data based on climate scenarios derived from the outputs of general circulation models (GCMs, such as HadGEM2-AO and CSIRO-Mk3-6-0) which project current and future climate based on different representative concentration pathways (RCPs). The results indicate that low impact development (LID) modules have better performance in the first growth period and may maintain domestic functionality under climate change. All indicators show positive correlations with rainfall in most of the climate scenarios. However, with slight decreases in predicted rainfall, the WUE and WSEₐgᵣᵢ showed negative correlations to rainfall in the RCP 2.6 HadGEM2-AO and RCP 4.5 CSIRO-Mk3-6-0 climate scenarios. This could be due the lower number of consecutive dry days predicted by the LF-WGEN causing a slightly increased wetland inflow that would then decrease the irrigation water supply. Overall, the community water supply system showed strong performance in the various climate scenarios. Further study of the community water supply system needs to include an optimization of adaptation measures for practical applications.