以地理資訊系統建立區域灌溉用水推估模式

台灣地區水資源之調配與管理長期以來均爲水利研討重要課題之一，尤其在當前面臨社會產業經濟轉型之際，各種用水標的之水權合理分配，一直是各方爭論之議題；但各標的合理用水量的估算，卻相當困難且不易取得各標的間一致之共識。其中農業灌溉用水量佔各標的總用水量約80%，但是由於農業區域廣大，作物種類繁多，土壤物理特性掌握不易，加上輸水渠道錯綜複雜，營運管理相當不易。農業灌溉用水之有效推估常涉及大量空間分佈之地理資料，很適合利用地理資訊系統來加以整合，但目前之地理資訊系統（GIS）軟體著重於空間資料庫之建立與管理，在相關之模式應用能力相當薄弱，需要自行撰寫程式或介面來整合GIS與應用模式。本文即透過地理資訊系統與農業用水推估模式之整合，評估利用地理資訊系統推估區域旬別灌溉用水量之可行性，經與灌區之計畫用水相比較，證實利用地理資訊可更快速準確的估算區域灌溉用水量；研究中亦發現由GIS建立之區域灌溉水量推估模式，可以快速反應如作物制度改變之土地利用變更對區域灌溉用水之衝擊，十分適合作爲未來發展區域用水規畫決策支援系統之工具。

關鍵字

灌溉用水；地理資訊系統；農業水資源

並列摘要

The water supply becomes a scarce resource from the rapid growth of water demand in Taiwan. Agricultural sector holds about 80% of the water right, and other water use sectors such as municipal and industrial need to get water supply from agricultural sector during the drought. There is a need for water right reallocation among water use sectors. But the demand estimations for each of the water use sectors are very difficult and controversial. The estimation of regional irrigation water demand involves tremendous information such as soil, crop, climatic factors, water distribution system, and management zoning. Most of these information are spatially distributed and will be more efficiently managed using Geographic information System (GIS) than traditional database. This paper proposed a combination of GIS and irrigation demand model for efficient and dynamic regional irrigation water demand estimation. A small command area about 4000 ha. of the ChiaNan Irrigation Association in Southern Taiwan was used as pilot study area. The algorithm are verified to be practical. Through the help of geographic database, the impact to irrigation demand from changing the cropping patterns can be evaluated with little effort. This combination of GIS and application model was found to be an efficient tool in building decision support system for regional water resource planning.

並列關鍵字

Irrigation demand ； Geographic information system (GIS) ； Agricultural water demand

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