期刊
WATER RESOURCES RESEARCH
卷 51, 期 1, 页码 685-703出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2013WR014572
关键词
arsenic; groundwater-fed irrigation; recharge; regression model; Bangladesh
资金
- UK's Engineering and Physical Sciences Research Council (EPSRC) through a Dorothy Hodgkin Postgraduate Award [GR/AKFX-DHPA]
- Wingate Geography Scholarship from the Harold Hyam Wingate Foundation, UK [4387]
Localized studies of arsenic (As) in Bangladesh have reached disparate conclusions regarding the impact of irrigation-induced recharge on As concentrations in shallow (50 m below ground level) groundwater. We construct generalized regression models (GRMs) to describe observed spatial variations in As concentrations in shallow groundwater both (i) nationally, and (ii) regionally within Holocene deposits where As concentrations in groundwater are generally high (>10 g L-1). At these scales, the GRMs reveal statistically significant inverse associations between observed As concentrations and two covariates: (1) hydraulic conductivity of the shallow aquifer and (2) net increase in mean recharge between predeveloped and developed groundwater-fed irrigation periods. Further, the GRMs show that the spatial variation of groundwater As concentrations is well explained by not only surface geology but also statistical interactions (i.e., combined effects) between surface geology and mean groundwater recharge, thickness of surficial silt and clay, and well depth. Net increases in recharge result from intensive groundwater abstraction for irrigation, which induces additional recharge where it is enabled by a permeable surface geology. Collectively, these statistical associations indicate that irrigation-induced recharge serves to flush mobile As from shallow groundwater.
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