應用未飽和層水平衡理論估計彰化地區地下水補注量之研究

本研究主要內容在建立一未飽和層水平衡理論來估計彰化地區地下水補注量，本文中考慮降雨期與非降雨期來探討未飽和區域內地表入滲行為及未飽和層土壤排水情形。首先選定彰化地區作為試驗地點進行土壤水力參數之推求，最後應用本模式於試驗地點進行降雨入滲對未飽和層地下水補注量之推估。本研究有兩項重要假設：（1）未飽和層內土壤飽和度呈均一性分佈（2）土壤蒸發散量與飽和度呈線性關係。降雨期間之地表入滲，根據Philip（1957）結合時間壓縮近似法進行模式之解析；非降雨期間，根據土壤飽和度隨時間於未飽和層之變動，求得未飽和層蒸發散與滲漏之解析解。為了解彰化地區地下水補注與現地參數之影響，選定彰化地區二十六鄉鎮作為試驗地點進行降雨入滲補注模擬之對象。在未飽和水平衡分析理論中，利用試驗地點之日雨量資料、氣象資料與地下水位資料，配合試驗地點所取得之土壤水力參數，進行試驗地點降雨入滲補注之模擬，最後應用未飽和理論於彰化地區未飽和層地下水補注量之探討。結果顯示，在不同降雨時間間距下地下水補注量推估結果介於3.76億噸至5.91億噸之間。經由分析比較後，以降雨時間間距0.2日估計之地下水補注量4.34億噸為較合理之估計量。

關鍵字

入滲；未飽和層；地下水補注；水平衡

並列摘要

This paper is put forth for estimating the ground water recharge in Janghauh area, using the framework of water budget of the unsaturated zone, with considering storm periods and interstom periods. A well-formulated approach is provided for evaluating surface infiltration and drainage in unsaturated zone. Two important assumptions in this study are given: an instantaneous uniform distribution of saturation degree and linear relationship between evapotranspiration and saturation degree. For the storm period, infiltration is described using well-known solution by Philip [1957] in conjunction with the time compression approximation. For the interstorm period, a solution is derived for the moisture depletion of a soil water reservoir that experiences simultaneous evapotranspiration and percolation. In order to evaluate the groundwater recharge in unsaturated zone, the daily rainfall data, meteorological data (e.g., temperature and Ep, etc), water table depths and in-situ hydraulic parameters in Janghauh area arc collected. Results show that the groundwater recharge in Janghauh area are 3.81 × 10^8 to 5.91 × 10^8 ton per year in different rainfall period. The groundwater recharge of 4.34 × 10^8 ton per year seems to be more reasonable when comparing with other estimated.

並列關鍵字

Infiltration ； Unsaturated zone ； Groundwater recharge ； Water budget

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