Application of fuzzy multi-objective function on reducing groundwater demand for aquaculture in land-subsidence areas

In Taiwan, due to its relatively low development cost, groundwater has been the main source of water supply for most aquacultural industry in costal areas. The overdraft of groundwater has caused serious land-subsidence in many parts of Taiwan. In addition to providing enough surface water for aquaculture freshwater demand, revising the aquaculture structure is one approach to reduce the reliance on fresh groundwater. Due to the most serious land-subsidence in Tachen Village, Changhua County, Taiwan, which may be caused by overusing groundwater for mainly raising freshwater clams, alternative techniques, such as changing the method of water use or revising the kinds of fish with less freshwater demands and higher gross profits, were studied in the study to reduce the dependence on fresh groundwater. The fuzzy multi-objective function comprising three single-objectives, viz. reducing saltwater demand, reducing freshwater demand, and increasing the total fisheries gross profit, was coupled with a global optimization algorithm to find suitable aquaculture scenarios in the study area. Analytical results can be provided to the fisheries authorities as references for revising the aquaculture structure.