Journal of Taiwan Agricultural Research

Author:Tsang-Sen Liu, Yu-Wen Lin, Wen-Jun Zhan, and Tsung-Ren Peng*

Abstract:

This study employed the end member mixing analysis (EMMA) approach constructed with hydrogen/oxygen isotopes (δ¹⁸O/δ²H) and chloride-ion (Cl^-) concentration to study the sources of groundwater in proximal-fan region and Bagua Tableland in Changhua County, Taiwan. This study also depicted the relationship among Zhuoshuixi stream water, Bagua Tableland groundwater, and plain groundwater in the proximal-fan region. The results indicate that approximately 47% of Bagua-Tableland groundwater comes from rainwater infiltration, and the remaining 53% from Zhuoshuixi stream water. The Zhuoshuixi stream water is the main source recharging groundwater in Changhua Plain, accounting for 68% of the total recharge of the proximal-fan groundwater. Of 68%,approximately 38% comes from direct recharge via the riverbed, and other 30% comes from the Bagua Tableland groundwater containing the stream water derived from the Zhuoshuixi. In other words, Zhuoshuixi stream water can be streamed to Bagua Tableland for irrigation. Thereafter, part of and the irrigation water may percolate to form groundwater of the Bagua Tableland, which then recharges groundwater in the Changhua Plain. This study not only semi-quantitatively confirms the importance of stream water of Zhuoshuixi to groundwater of Changhua Plain, but also verifies the circularity of agricultural irrigation water.

 

Key words:Agricultural irrigation water, Stable hydrogen and oxygen isotopes, Natural tracer approach, Proximal-fan groundwater, Changhua

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