本研究選取桃園大圳二支線為研究區域，由二支線水庫水源、河水堰河川水源與埤塘水源等三種灌溉水源建立灌溉系統，在降雨提供之有效雨量與有限灌溉水源下，運用94年資料進行灌溉用水模擬。模擬結果顯示，二支線位於下游5個不具埤塘之灌區會呈現缺水情況，在利用深水灌溉理論，提高降雨時灌區有效雨量之蓄存，增加210mm有效雨量值，有效減少灌區總缺水量與縮短缺水天數。分析近10年3月3日~6月30日雨量資料，以91年總降雨量350mm最低，以降雨分布模擬埤塘調蓄容量，將二支線29個埤塘劃分上下游區域，結果顯示上游埤塘貯蓄容量為最大容量的70％，下游埤塘貯蓄容量為最大容量，所消耗二支線取入量為最大，灌區總缺水量最小。 A pond irrigation system model which is capable of satisfying water demand in an area with canals, weirs and ponds is developed in Taoyuan County, located in northwest Taiwan in early twenty century. The purpose of this study is to investigate the possibility to reaccess the original function of this pond irrigation system by utilizing a system simulation model. It is shown that making fully use of the effective rainfall could cut down agricultural water demand and promoting the water usage efficiency in farmland. Furthermore, it can promote irrigation efficiency with the increasing of the capacity of critical water ponds. On the other hand, to adopt deep ponding irrigation method can also enhance the efficiency in utilizing rainfall and runoff. In other words, it makes paddy fields as reservoirs to store more rainfall to meet crop water requirement.
