Zonal management of multi-purpose use of water from arsenic-affected aquifers by using a multi-variable indicator kriging approach

SummaryThis work presented a probability map of groundwater resources for multi-purpose uses (irrigation, aquaculture and drinking water) of arsenic (As)-affected aquifers in the Lanyang Plain, northeastern Taiwan. The assessment was based on As and other several compounds and factors that adversely affect water-quality. Multiple-variable indicator kriging (MVIK) was adopted to evaluate numerous hydrochemical parameters for the three water-quality standards in Taiwan. Hydrochemical parameters of groundwater were classified into four main hazard categories – saline hazard, nitrogen hazard, As hazard and Fe–Mn hazard. Safe and potentially hazardous groundwater regions for multi-purpose use were delineated according to estimated probabilities by using MVIK. Analytical results for MVIK critical probability of >0.5 demonstrate that the proximal-fan, partial central distal-fan and mid-fan, and northern distal-fan aquifers complying with most water-quality standards are optimal zones for extracting safe groundwater. Notably, the deep aquifer has a high hazard rating and is less safe than the shallow aquifer. The Fe–Mn hazard in Lanyang Plain groundwater presents in most aquifers, and is partially combined with other hazards, such as the nitrogen hazard and the As hazard. A zonal management plan based on safe groundwater use is formulated to help local governments develop groundwater resources in the Lanyang Plain.