Probabilistic assessment of safe groundwater utilization in farmed fish ponds of blackfoot disease hyperendemic areas in terms of the regulation of arsenic concentrations

This work probabilistically explored a safe utilization ratio (UR) of groundwater in fish ponds located in blackfoot disease hyperendemic areas in terms of the regulation of arsenic (As) concentrations. Sequential indicator simulation was used to reproduce As concentrations in groundwater and to propagate their uncertainty. Corresponding URs of groundwater were obtained from the relationship of mass balance between reproduced As concentrations in groundwater and the As regulation in farmed fish ponds. Three levels were adopted to evaluate the UR — UR ≥ 0.5, 0.5 > UR ≥ 0.1 and UR < 0.1. The high probability of the UR ≥ 0.5 level presents in the northern and southern regions where groundwater can be a major water source. The high probability of the 0.5 > UR ≥ 0.1 level is mainly distributed in the central-coastal, central-eastern and southeastern regions where groundwater should be considered as a subordinate water source. Being available, extra surface water has priority over providing aquacultural needs of the regions with the high probability of the UR ≥ 0.5 and 0.5 > UR ≥ 0.1 levels. In the regions with the high probability of the UR < 0.1 level, in the central-coastal and southwestern regions, groundwater utilization should be reduced substantially or even prohibited completely for no adverse effects on human health.