| 摘要: | 台灣目前輪區灌溉用水多以人工操作配水，導致輪區之灌溉水量無法精密控管，調控過程之輸水損失亦無法精確計算。而隨著氣候變遷導致豐枯水期降雨不均現象更加遽烈，若能由用水量最大宗的農業，以精密灌溉調配，節省部分用水，則可有效提升水資源調配空間。本研究運用系統動力模式建立農業灌溉用水系統，結合降雨及灌溉之水源，以豐水年2013 年資料分別針對新永基幹線北幹線1~5 輪區之原灌溉計畫書配水量、減供30%灌溉配水量、減供50%灌溉配水量進行模擬，分析原灌溉計畫書配水之合理性。針對原灌溉計畫書配水及減供30%灌溉計畫配水，於一期作枯水期模擬結果顯示，田間水份含量皆未低於田間含水量，僅減供50%灌溉計畫配水，於灌溉次序最後之第五輪區，田間土壤含水量會有低於土壤凋萎點之結果。由此評估原灌溉計畫配水仍有調整空間。
2015 年於試驗灌區，以本研究建立之模式模擬灌溉需水量後，提供田間自動控制水門進行閘門開度計算，並自動調控配水，探討田間自動灌溉管理機制之可行性。於自動控制水門動態調整案例，節省一日灌溉水量約7.9 萬噸，而自動控制水門於1 小時內，調整至目標流量過程中，平均多放526.5 噸水量，調控結果誤差為1.79%。本研究結果顯示以田間精密灌溉用水模式計算之結果，配合田間自動控制水門調整流量，可達節省灌溉用水之效果。;In Taiwan, most irrigation water distribution depends on manual work,
meanwhile, the water of irrigation and the lost from the conveyance can
not be accurately calculated. This situation turns worse as the climate
change leads to uneven rainfall. If the water usage in which accounts for
70% of water usage, can be allocated more precisely, it would improve
water resource allocation effectivity. This study applies system dynamic
model to establish irrigation water management model, combining rainfall
and irrigated water, the model simulated two scenarios by decaeasing 30%,
and 50% planned irrigation water in the wet year 2013. The result shows
that field capacity of the end of the tested area, no. 5 round regin, will lower
than wilting point, under 50% decreased water of irrigation plan. It appears
that the original irrigation plan still have some extra reduction in the future.
To probe the feasibility of automatic irrigation in the field, the model,
built by this study, was used to estimate the demand of irrigation to the test
area in the first crop, 2015. After sending to the cloud data center, the
calculated flow will be acquired at the timing of every 2 hours by the
automatic gate in the field, and the gate achieves flow adjustment in 1 hour.
During testing period, because of the out flow always greater than 0.5 times
of the inflow, the threshold set by this study for saving water, the gate can
only operate under the target flow 0.46cms. However, the automatic
operation result shows about 7.9 tons/day can be saved from the dynamic
adjustment, and comparing to the target flow, only 526.5 tons water lost
during the operating hour, with the error ratio being 1.79%. The
contribution of this study provide the effectivity in water saving with the
combination of accurate irrigation model and automatic adjustment gate. |
