集水區土地利用變遷及降雨量變化對水資源涵養能力影響之研究

Effects of Changes in Land Use and Rainfall Patterns on Water Resources Conservation Capability in a Watershed

何嘉浚(Chia-Chun Ho) ； 曾俊偉(Chun-Wei Tseng) ； 李嘉莙(Chia-Chun Lee) ； 林鎮洋(Jen-Yang Lin) ； 莊智瑋(Chih-Wei Chuang)

《台灣林業科學》 34卷4期 (2019/12) Pp. 217-233

https://doi.org/10.7075/TJFS.201912_34(4).0001

摘要

臺灣年平均降雨量2500 mm，因受降雨時空分布不均、地勢陡峻、河短急流影響導致水資源蓄留不易。近年更因社會經濟蓬勃發展、平地開發已趨飽和，逐漸朝向山坡地發展，使原有水文循環系統產生巨大改變。因此，瞭解土地利用變遷及降雨型態變化對水資源涵養量影響乃是目前重要課題之一。本研究以臺灣中部水里溪集水區為研究樣區，利用美國環保署開發之BASINS/HSPF水文模式進行量化評估，研究結果如下：（1）分別以2009及2010年資料進行參數率定及驗證，結果顯示相關係數（correlation coefficient, r）分別為0.87及0.72；決定係數（determination coefficients, R^2）分別為0.75及0.52；模式有效性係數（efficiency coefficient, E）分別為0.39及0.11，表示模式具有可靠性。（2）以四個年度土地利用進行模擬，顯示其水資源年涵養率為23.37～23.82%，再與土地利用交叉比對，發現以森林與建物面積對集水區水資源涵養量影響最大；（3）選取較易影響水資源涵養量之三種土地利用型態（森林、農業及建地）進行6種情境模擬，顯示將森林開發為建地對水資源涵養劣化影響最為明顯；（4）經由豐枯水年之年降雨量進行模擬，發現豐水年因降雨豐沛，雨水儲蓄於集水區能力較佳，水資源年涵養率約26%。

關鍵字

BASINS/HSPF水文模式 ； 水資源涵養 ； 土地利用 ； 情境模擬

並列摘要

The average annual rainfall in Taiwan is about 2500 mm. Because of the uneven distribution of rainfall in time and space, the steep terrain, short rivers, and rapid flow, water resources cannot easily be stored. In recent years, due to the vigorous development of the social economy, development of lowlands has become saturated, and development has gradually expanded towards slope land; this has brought tremendous changes to the original hydrological cycle system. Therefore, understanding the impacts of changes in land use and rainfall patterns on water resources conservation is an important issue at present. The Shui-Li Creek watershed in central Taiwan was selected for this study. A quantitative assessment of water resources conservation in the study area was conducted using the BASINS/HSPF hydrological model which was developed by the US Environmental Protection Agency. The following research results were documented. (1) The parameters were calibrated and verified by flow data of the years 2009 and 2010, respectively. The results showed that the correlation coefficients (r) were 0.87 and 0.72, the determination coefficients (R^2) were 0.75 and 0.52, and the efficiency coefficients (E) were 0.39 and 0.11, respectively. This indicates that the model was reliable. (2) Simulation results of land use patterns in four periods showed that rates of annual water resource conservation were 23.37 to 23.82%. After a cross comparison of land use, it was found that patterns of forests and buildings had the greatest impacts on water resources conservation in watershed areas. (3) Three patterns of land use (forest, agriculture, and buildings), which can easily affect water resource conservation, were selected for six simulation scenarios. Results showed that land use change from forests to buildings had the most obvious impact on water resource conservation. (4) Comparisons of water resource conservation of the annual rainfall in high-flow and dry years showed that rainfall which was stored in the watershed area in a high-flow year was better due to the abundant rainfall. The rate of annual water resource conservation was about 26%.

並列關鍵字

BASINS/HSPF hydrological model ； water resource conservation ； land use ； scenario simulation