結合水質與生態模式-以新山水庫為例

Abstract

新山水庫供給基隆地區的用水，水質為輕度優養化之狀態，而造成新山水庫優養化的主要原因是由於磷與氮的大量輸入，輸入的主要原因是因為進入的基隆河原水中含有大量的營養鹽，本研究使用Vollenweider零維總磷質量平衡模式、WASP5水質模式以及Ecopath生態模式進行模擬與研究。 以Vollenweider零維總磷質量平衡模式分別針對新山水庫2004、2005年的數值進行參數檢定與模式驗證，可以發現此模式適用於新山水庫。所模擬出來的結果可以發現，模擬值與實測結果兩者有相同的趨勢且結果相近。以WASP分別針對新山水庫2004、2005年的數值進行參數檢定與模式驗證，可以發現此模式也同樣適用於新山水庫。並且對新山水庫2004、2005年水質進行優養分析預測，水質指標降低至中養時，大約需要削減入流磷系統30∼40%左右，而要達到貧養的程度，需要消減入流磷系統70∼80%左右，顯示新山水庫的入流水質不佳為水庫優養化的主要原因。生態模擬部分使用Ecopath生態模式模擬新山水庫，整個系統的初級生產量除總呼吸量為1.228，可得知新山水庫是一個相對接近成熟的生態系統，水庫中族群變化相對的穩定。 本研究將Ecopath結合WASP模式，以計算於水庫中放置珍珠貝，利用其攝食藻類的特性，來改善新山水庫的水質狀況的效果，珍珠貝顆數與葉綠素a濃度的方程式計算出來為 y = 69378 exp(-0.3442x)，其中y為顆數，x為葉綠素a的濃度[ ppb ]。並且進行Ecopath結合WASP模式之敏感度分析，藉此來了解各參數對於攝食率的影響程度，結果可以看出在生物量、單位生物量之代謝消耗量與生態利用效率，假使生物層級越高，對於浮游植物（葉綠素a）的影響越小，但是單位生物量之生產量不管如何改變，對攝食率是沒有影響的。

Hsin-Shan Reservoir provides the water supply of Keelung. The main source of this reservoir is Keeling River. Keelung River is a very polluted river because of the drainage of commercial, industrial and residential. According to Carlson Index, its water quality is in eutrophication level. Phosphorus and nitrogen of Keelung River is the main reason of eutrophication. This research uses three models, Vollenweider, WASP, and Ecopath, to analysis the water quality of reservoir. In the end, we establish a way for providing a biological treatment evaluation method. The field data of 2004 and 2005 is collected in the research. The main reason of eutrophication in Taiwan is phosphorus. Vollenweider is used as a total phosphorus mass balance modeling to simulate the Hsin-Shan Reservoir. The result is quite well. The maximum concentration is happened in summer. Next, we use WASP to do more explicit simulation. The result WASP shows a good trend and very closed to the field data. We use WASP to see how many pollutants should be reduced if we want the water quality is no more eutrophication level after the model established. According to our analysis, if we want to reach the mesotrophic level, 30 to 40% pollutants would need to be removed from inflow. Further more, if we cut down 70 to 80% pollutants, the whole reservoir would be in oligotrophic level. These two models showed that the main pollutant source is the Keelung River and the eutrophication is happened in summer period. In order to understand the ecosystem of Hsin-Shan Reservoir, we use Ecopath as ecological model. The outcome shows, the total primary production/total respiration of Hsin-Shan Reservoir is 1.228. It can say the ecosystem of Hsin-Shan Reservoir is very close to the mature one. In recent year, more and more biological treatment methods are used to replace the traditional construct methods. The main problem of biological treatment is the difficult of evaluate the effect of biological treatment. We try to put some pearl shell in reservoir to control phytoplankton. Before field exam, we used models to estimate the effect of such a work. This research combines the models of WASP and Ecopath to calculate the erasing rate relationship between pearl shell and phytoplankton. The equation of the pearl shell number and chlorophyll a concentration is y = 69378 exp(-0.3442x), here y is the number of pearl shell, x is the concentration [ppb] of chlorophyll a. The result shows if we want to reach mesotrophic level, about 3000 pearl shell will be needed.