| Summary: | 碩士 === 國立臺北科技大學 === 土木工程系土木與防災碩士班 === 104 === Aquifer vulnerability assessment is considered an effective tool in groundwater management which is necessary for controlling potential pollution. The Choushui River alluvial fan, located on central Taiwan, is an area of mixed agricultural region, where complex crop patterns and various rotational cropping schemes increase the difficulties in groundwater resource management. The aim of this study is to propose an integrated methodology to assess shallow groundwater vulnerability by including land-use impact on groundwater potential pollution. The original groundwater vulnerability methodology DRASTIC, developed by USEPA, was modified by adding a land-use parameter in order to assess groundwater vulnerability under intense agricultural activities. The crop pattern, fertilizer application rate, and irrigation method were taken into account in the land-use parameter. To examine the prediction capacity of pollutions for the modified DRASTIC model, various risk categories of contamination potentials were compared with observed nitrate-N obtained from groundwater monitoring network. It was found that for the original DRASTIC vulnerability map, some areas with low nitrate-N concentrations are covered within the high vulnerability areas, especially in the northern part of mid-fan areas, where rice paddies are planted for two crop seasons per year. This may due to the paddy environment could reduce the nitrate-N concentration by denitrification effect. The modified model was proved to be capable of increasing the precise of prediction in this area by reducing the vulnerability in this area but not affect the other high vulnerability areas. The results can provide a basis for groundwater monitoring network design and effective preserve measures formulation regarding the state of the environment.
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