桃園埤塘輪灌系統之模擬分析

The Simulation of Pond Rotation Irrigation System in Taoyuan

許良瑋(Liang-wei Hsu)

指導教授 ： 吳瑞賢

國立中央大學/工學院/土木工程學系/碩士(2011年)

摘要

本研究利用系統動力模式模擬農業灌溉系統，考慮降雨提供之雨量及有限灌溉水源，分別以枯水年2003年和豐水年2007年之資料進行灌溉用水模擬，分析埤塘在枯水年與豐水年之調蓄功能。經由不同的埤塘操作之方式探討其調蓄效益。本研究選取桃園大圳二支線為研究區域，二支線之灌溉水源取自於石門水庫、埔心溪及南崁溪，而桃園地區內的埤塘灌溉系統為特有農業灌溉方式，不僅可以提升降雨量之使用率，更能調蓄輔助農業灌溉用水。
針對埤塘灌溉系統對於農業灌溉之重要性，考慮埤塘系統灌溉灌方式上共有三種不同之操作：埤塘調蓄、埤塘部分調蓄及埤塘關閉進行模擬，發現使用埤塘調蓄對於減少大圳供水壓力有顯著效果。並藉由二支線在不同供水比例下，發現埤塘調蓄對於減少灌區缺水的現象優於其他操作方式，由此證實在實施節省灌溉用水下，埤塘調蓄扮演著重要的角色。
隨著氣候變遷，極端降雨的現象越來越明顯，缺水現象愈加頻繁。本研究分析缺水時期輪灌與續灌調配灌溉用水之優劣，以及實施打折供水的情況下，減少灌溉面積以延長正常農作之天數，並假設為無降雨之高風險情況。結果顯示，輪流灌溉法之配水制度優於繼續灌溉法，且由枯水年模擬結果發現38個灌區中，在灌溉面積減少為60%時，埤塘關閉及埤塘部分調蓄僅能使11個灌區整期作維持正常農作，而埤塘調蓄維持之正常農作灌區數量為28個。由此可知，配合埤塘調蓄實施減少灌溉面積策略，有助於大部分灌區延長正常農作天數。研究結果顯示埤塘對於氣候變遷對水資源利用所帶來的衝擊有緩和的功用。

關鍵字

桃園大圳 ； 輪流灌溉 ； 水稻田 ； 系統動力模式 ； 埤塘灌溉系統

並列摘要

This research investigated the influence of irrigation water requirement with pond irrigation operation. The pond irrigation system has the advantage of regulate irrigation water. Tao-Yuan Channel #2 Feeder is selected as the study area. The irrigation water resources included Shih-men reservoir, Nankan stream and Puxin stream. The pond irrigation system model was established by adapting Vensim model and the irrigation water record in 2003 and 2007 were applied.
Simulations of various irrigation management approaches are used to estimate the significance of pond irrigation system. The simulation was formulated into three cases: (1) pond operated, (2) pond partial operated, (3) pond closed irrigation system. For cases of insufficient water supply, the result shows that pond irrigation system can reduce the burden of canal supply and the risk of shortage significantly.
The hydrologic pattern changes due to climate change increases the difficulty in irrigation system management. The study compared the performance of the rotation irrigation approach and that of the continuous irrigation approach during drought period. Assuming that both the water supply and irrigation area are reduced in order to maintain normal cultivation days during no rainfall condition, the result shows the rotation irrigation approach outperformed the continuous irrigation method. Given the case that the irrigation area is reduced to 60% for all irrigation sections during the dry season, both the without pond irrigation system and the pond partial operated system were able to keep normal crop cultivation for only 11 out of 38 irrigation sections. However, In the case of the pond operated system, 28 irrigation sections were kept normal crop cultivation. Therefore, the strategy of reducing irrigation area with the pond operated system can help in keeping normal cultivation days for the majority of irrigation area. In conclusion, the pond irrigation system has positive effect on relaxing the climate change impact on water resource management.

並列關鍵字

Vensim model ； Pond irrigation system ； Taoyuan Main Canal ； Paddy field ； Rotation irrigation

參考文獻

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