Groundwater vulnerability assessment to nitrate pollution in Pingtung Plain of Southern Taiwan

A long-term groundwater quality survey revealed that NO3--N concentration in the some monitoring wells of the Pingtung Plain of southern Taiwan exceeded the Taiwanese standards for drinking water quality of 10 mg/L. Therefore,... [ view full abstract ]

A long-term groundwater quality survey revealed that NO3--N concentration in the some monitoring wells of the Pingtung Plain of southern Taiwan exceeded the Taiwanese standards for drinking water quality of 10 mg/L. Therefore, efforts for assessing groundwater vulnerability are required to prevent and control groundwater pollution. This study attempts to perform a groundwater vulnerability assessment in the Pingtung Plain using a modified overlay index-based DRASTIC model. The modification of the DRASTIC model is achieved by reassigning the weighting coefficients of the factors in DRASTIC with the help of a discriminant analysis statistical method The analytical results the modified DRASTIC model can effective promote the prediction performance for groundwater vulnerability assessment to nitrate pollution and correctly identify the groundwater protection zones in Pingtung Plain. Moreover, the results of the sensitivity analysis of the seven factors in the modified DRSSTIC model demonstrate that the aquifer media (A) is the most sensitive factor when the nitrate-N concentration is below 3 mg/L. For the nitrate-N concentration is above 7.5 mg/L, the aquifer media (A) remains the most important factor, followed by net charge (R).