水資源的運用可分為兩大方面，一為供給；一為需求。在供給不足的情況下必須有效調配各標的之用水需求，以供應公共、民生用水不虞匱乏。如何在平時將豐水期多餘之水量儲存，適當調配至枯水期運用，以充分供應各標的之用水需求，為本研究之主要目的。 本論文著重於方法論之研究，以嘉南地區為案例，配合曾文水庫水庫規線操作，於水庫蓄水量不足時，將水資源供給分為兩部分，一為上游水庫蓄水；一為下游降雨。本研究考量上游水庫蓄水主要提供給下游用水，包括民生、農業、工業及公共給水，故水庫蓄水量有時會有匱乏不足的情況發生。研究中假設研究年之第15旬至第25旬之水庫入流量及蓄水量為已知值，於研究年中利用第25旬之水庫蓄水量及迴歸週期入流量，判斷是否需限水操作。在計算上利用區域化變數理論及蒙地卡羅模擬，推求未來水庫之缺水機率及作物存活機率。結果顯示，由於二期作之降雨量較一期作時期為高，故二期作不足的作物水量由降雨量補足的機率將會較一期作由降雨量補足的機率高。本研究結論建議，在不改變耕作面積的條件下，可供給一期作充足的灌溉用水量以使其作物存活機率提高，而二期作則在可忍受的作物存活機率降低所造成之經濟損失下，折減其灌溉用水，減供之水量可預留供給隔年一期作的灌溉用水。 The analysis of water resource can be divided into two parts, supply and demand. When supply is not enough, it is necessary to adjust demand of each aims to minimize the inconvenience of public and civil use. The purpose of this research is to store the water resource during the wet period and adjust the water supply in dry period appropriately to supply every aims efficiently. This paper emphases on the methodology of drought management. In the case of Jia-nan District, when the reservoir storage is lower than usual, reservoir operation rule curves are applied. In this study we focus on two elements in water resources system, one is upstream reservoir storage, and the other is downstream rainfall. This research considers that upstream reservoir storage primary supply downstream uses, including civil, agricultural, industrial, and public use. It is assumed that we have known the inflows and the storage during the periods from the fifteenth to the twenty-fifth period. The reservoir inflows and the storage of the twenty-fifth period is used to determine whether we need to limit water use. The theory of Regionalized Variables and Monte Carlo simulation was employed to calculate the probability of water lack and crops survival rate. The result shows that because the rainfall of second plow season is more than that of the first plow season, the probability of water lack during the second plow season is higher than that of first plow season. In conclusion, one should supply the first plow season sufficient irrigation water to raise the survival rate of crops. We reduce the irrigation water during second period plow and the stored water can supply for the first period plow next year.
