| Summary: | 博士 === 國立成功大學 === 資源工程學系碩博士班 === 97 === The principal objectives of this dissertation are to investigate the groundwater resources in mountainous basin through a set of detailed case studies. This dissertation is mainly divided into three major parts including: (1) groundwater recharge estimation; (2) groundwater recharge potential zone mapping; and (3) groundwater recharge characteristics evaluation. The first part is to apply a water balance concept with two methods to estimate the groundwater recharge in the Ching-Shui Creek basin. A soil moisture budget method is established to estimate the infiltration, runoff, evapotranspiration, and groundwater recharge in the basin, where the moisture content of the soil is tracked through time. Both soil-water properties of the unsaturated zone and climatic conditions must be fully considered. The base-flow model uses the base-flow separation from the total streamflow discharge to obtain a measure of groundwater recharge, where groundwater evapotranspiration is negligible. In contrast to the soil moisture budget method, base-flow estimation does not require complex hydro-geologic modeling and detailed knowledge of soil characteristics.
The second part is to assess the potential zone of groundwater recharge. The Chih-Pen Creek basin in eastern Taiwan is examined in this study to assess its groundwater resources potential. Remote sensing and the geographical information system (GIS) are used to integrate five contributing factors: lithology, land cover/land use, lineaments, drainage, and slope. The weights of factors contributing to the groundwater recharge are derived using aerial photos, geological maps, a land use database, and field verification.
The final part is to use the stable isotopes of oxygen and hydrogen to estimate the sources of groundwater and seasonal contributions of precipitation to groundwater recharge in Chih-Pen Creek basin. Precipitation, river water, and groundwater samples are collected for oxygen and hydrogen isotopic analyses between January and December, 2007. Sampling is carried out during both wet and dry periods. Using a mass-balance equation, a comparison of deuterium excess or d-values of precipitation and groundwater indicates the groundwater consist of 76% wet season precipitation and 24% dry season precipitation, representing a distinct seasonal variation of groundwater recharge in study area. About 79% of the groundwater is recharged from the river water of the mountain watershed and 21% is from the rain that falls on the basin.
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