Effectiveness Assessment on Groundwater Recharge with Ponding Water Depth in Fallow Paddy Fields

• Main Authors: Hsin-MingHuang, 黃信茗
• Other Authors: Chyan-Deng Jan
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/98350679366508695617

博士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 100 === The paddy fields have multiple functions of production, livelihood and ecology. Due to series of agricultural policies to encourage the reducing the rice production and transfer by the agricultural authorities of the Taiwan Government, it has resulted in an apparent impact to the rice production structure. In the wake of domestic agricultural development as the change in the effective application of existing resources and to increase crop production and quality conditions, the long-term irrigation of rice fields has become an important source of groundwater recharge. The focus of the study were to the simulation of groundwater recharge from the ponding water of the fallow paddy fields, also to study the water transfer within soils and to develop quantified index of groundwater recharge.The research results will also be the basis for future promotion. The study site was located in the Lan-Yang Plain of Ilan County, where the groundwater in the area is abundant due to the alluvial layer of gravel in the upstream region. This site is a good groundwater recharge zone with high water conductivity and water storage. The study adopted the MODFLOW of the Groundwater Modeling System (GMS) to simulate the groundwater flow and evaluate the effect of different water depths to the groundwater recharge. The results showed that: (1) The higher the recharge water depth, the higher the amount of water inflow and outflow.This is due to different gradient by different water storage depth. (2) The inflow in the sandy or gravel soil texture is more than the muddy soil and so does the outflow. Therefore indicate a slightly worse recharge efficiency. (3) The groundwater recharge of the sandy soil and gravel is higher due to greater hydraulic conductivity. However, the sandy soil and gravel retain less water than the muddy soil in the field. Therefore a mixture of the sandy and muddy soils is the best for groundwater recharge in the fallow paddy field. (4) The soils in the Touchen, Chiaoxi, and Chuangwei stations have the characteristics of mixture of sandy and muddy soil. These areas are appropriate for water storage in the fallow paddy fields. (5) It can be proved by the equal water level map that the sandy-muddy mixed soil is the most suitable for the groundwater recharge zone. Although the recharge amount is high from the gravel zone, the recharge efficiency is low. (6) The storage depth of 25 cm has the best efficiency for the second crop period at the Lan-Yang plain.