Establishing an irrigation management plan of sustainable groundwater based on spatial variability of water quality and quantity

Conditions of water quality and quantity are two key factors impacting groundwater utilization for irrigation. To obtain pristine groundwater and reduce pumping impacts on aquifers, this study establishes an irrigation management plan of sustainable groundwater in the Pingtung Plain in Taiwan based on the spatial variability of water quality and quantity parameters. According to an irrigation water quality standard, multivariate indicator kriging (IK) was adopted to estimate the integration of hydrochemical parameters in groundwater. IK was also used to grade transmissivity fields representing the pumping capacity of aquifers. Six risk categories of recommended groundwater used for irrigation were spatially delineated based on combinations of five levels of groundwater quality and quantity determined by estimated probabilities. The analyzed results indicate that 54.4% of aquifers are recommended to extract groundwater for irrigation. The aquifers belonging to excellent categories are the optimal locations, where groundwater can be used for irrigation without dilution. The aquifers belonging to ordinary categories are the regions, where groundwater mixed with surface water is appropriate for use in irrigation.