水庫湖泊磷內部負荷之模式推估

Abstract

針對水庫本身內部所產生之污染負荷，國內相關研究較少，一般是假設空 間平均分佈或依質量平衡方式大略估計內部負荷量，此估計量可能不適用 於規劃詳細的污染控制計畫，本研究因而試著建立一個較可靠的磷內部負 荷推估程序，除了提供較可靠的估計外，並可用以分析空間分佈特性。所 發展的程序包括資料收集與處理、採樣點的選擇與規畫、模式單元分割、 不同時期不同單元水體之底泥採樣及實驗室監測以取得磷釋出率參數之可 能範圍、使用美國EPA發展出之水質模擬程式WASP5模式進行水質模擬、使 用AGNPS模式進行外部負荷之模擬與估計及磷內部負荷之率定與驗證等。 本研究之案例研討是以寶山離槽水庫在為期90天之時期內來驗證預設程序 之可利用性，由磷釋出之率定結果可看出磷內部負荷具有季節性明顯變化 之特性，而且模擬推估出之磷內部負荷量與質量平衡方式計算得之結果有 很大之差別，由案例研討可確信此程序能改進內部負荷之估計，也期望此 程序能適用於國內其它水庫內部負荷之推估工作。 Pollution load generated internally from a reservoir itself was rarely studied in Taiwan and the amount of such load was generally estimated on the basis of overall mass balance and its spatial distribution was generally assumed to be uniform. Such a rough estimation and assumption may not be appropriate for a detail pollution control plan. This research was therefore initiated to explore an appropriate phosphorous internal loading estimation procedure for providing reliable estimation and spatial distribution. The developed procedure includes data colluction and processing, sampling equipment selection and planning, modeling segmentation, sampling and laboratory analysis for parameters including phsophorous release rate in different water body segment and time interval, the use of WASP5 model developed by U.S. EPA for water quality simulation, external loading simulation and estimation using AGNPS, and internal loading calibration and verification. The case study for Po-San off-channel reservoir was implemented to demonstrate the utilization of the proposed procedure for a 90 day period. Significant seasonal variation of phosphorous release and difference between the results obtained from mass balance method and the proposed procedure were observed. The procedure is believed to be able to improve internal loading estimation for the case study area and is expected to be suitable also for other reservoirs in this country.