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Holistic blue water use and life cycle cost savings of domestic and agricultural rainwater harvesting at the watershed scale in the Southeast US
Citation:
Ghimire, S. AND JohnM Johnston. Holistic blue water use and life cycle cost savings of domestic and agricultural rainwater harvesting at the watershed scale in the Southeast US. 2017 Annual Meeting of the Georgia Environmental Conference, St Simons, GA, August 23 - 25, 2017.
Impact/Purpose:
Oral presentation at the Annual Meeting of the Georgia Environmental Conference, Aug 23-25, 2017, St. Simons Island, GA
Description:
According to the U.S. Global Change Research Program, from 1970 to 2007 most of the Southeast U.S. received heavy downpours in recent autumns while moderate-to-severe drought increased in spring and summer (12% and 14%). Rainwater harvesting (RWH) is getting attention due to recent droughts in the region; however, RWH adoption is hindered due to limited understanding of the economic, social, and environmental implications. Domestic R WH stores rainfall from rooftops for non-potable uses such as lawn and garden watering. Agricultural R WH utilizes constructed ponds to capture storm runoff, diverting surface water to storage and use for watering crops in lieu of or in combination with groundwater pumping. We present findings of a recent study that evaluated water balance and cost implications of R WH in three watersheds within the Albemarle-Pamlico river basin (NC and VA). Functional unit life cycle impact scores for near-optimal domestic and agricultural RWH system adoption rates of25%, 50%, 75%, and 100% were compared to conventional municipal water and well water systems. Overall, R WH outperformed conventional sources in a majority of impact categories in the three watersheds, including energy use, greenhouse gas emissions, blue and green water use, and human health impacts. The importance of understanding holistic water balance (blue water as surface/ground water), green water (rainwater) use and life cycle costs are discussed. Holistic water balance analysis incorporating annual rainfall effects in life cycle water balance revealed greater annual holistic blue water savings for agricultural RWH (at 100% adoption) for Back Creek (2.4 Mm3/y) than Sycamore Creek (0.1 Mm3/y). Potential maximum lifetime energy cost savings were estimated at $5M and $24M corresponding to domestic RWH in Greens Mill watershed and agricultural RWH in Back Creek watershed. The methodology is generally applicable to regions with comparable watershed characteristics, installation costs, and treatment options. Future research is directed towards upscaling agricultural RWH impacts at the river basin scale.
