Collins Kissi Asante-Sasu , Jon Turk , Seann McClure , Alexandra McLarty
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引用次数: 0
Abstract
The Columbia Plateau Regional Aquifer System (CPRAS) is a layered basalt aquifer system that underlies the Columbia River Basin in Washington, Oregon, and Idaho. The CPRAS covers a large spatial area and is undergoing water level declines that threaten water supply. It supports agriculture, economic development, and ecological systems. The heterogeneity of the aquifer system means each aquifer layer is experiencing different levels of groundwater storage change even at the same location. The goal of this study is to evaluate the magnitude and spatial variability of groundwater declines and vulnerability across the aquifer layers. We computed groundwater level trends using the Sen Slope estimator, in each aquifer layer and by subareas in the Washington portion of the CPRAS. The trends are projected into the future and combined with changes in available drawdown to evaluate groundwater vulnerabilities in the present (2020) and the future (2040) for each aquifer layer. The vulnerability assessment only uses trends that are statistically significant at a 95 % confidence level based on the Mann-Kendall test. The largest groundwater level declines were observed in the Grande Ronde aquifer layer, with a mean decline of 1.86 ft/yr, followed by the Wanapum aquifer layer with a mean decline of 1.61 ft/yr. Declines within the Saddle Mountains and Overburden layers are an order of magnitude smaller, with mean declines of 0.56 ft/yr and 0.22 ft/yr, respectively. Although there were higher groundwater level declines in the Grande Ronde layer, the available drawdown of this layer is greater, leading to lower levels of vulnerability. However, in the Overburden layer, the available drawdown is small, driving higher groundwater vulnerability. Evaluating groundwater vulnerability based on the available drawdown rather than total aquifer saturated thickness gives a more realistic assessment of vulnerability because groundwater below well depths is not accessible without infrastructure changes.
期刊介绍:
Groundwater for Sustainable Development is directed to different stakeholders and professionals, including government and non-governmental organizations, international funding agencies, universities, public water institutions, public health and other public/private sector professionals, and other relevant institutions. It is aimed at professionals, academics and students in the fields of disciplines such as: groundwater and its connection to surface hydrology and environment, soil sciences, engineering, ecology, microbiology, atmospheric sciences, analytical chemistry, hydro-engineering, water technology, environmental ethics, economics, public health, policy, as well as social sciences, legal disciplines, or any other area connected with water issues. The objectives of this journal are to facilitate: • The improvement of effective and sustainable management of water resources across the globe. • The improvement of human access to groundwater resources in adequate quantity and good quality. • The meeting of the increasing demand for drinking and irrigation water needed for food security to contribute to a social and economically sound human development. • The creation of a global inter- and multidisciplinary platform and forum to improve our understanding of groundwater resources and to advocate their effective and sustainable management and protection against contamination. • Interdisciplinary information exchange and to stimulate scientific research in the fields of groundwater related sciences and social and health sciences required to achieve the United Nations Millennium Development Goals for sustainable development.