砂箱模型模拟休耕田区以砂桩补注地下水对溶质传输影响

水田在休耕期间蓄水,除了可维持水田原有之生态机能外,亦可增加土壤水分涵养与补注地下水.利用砂箱来模拟休耕田区中打入砂桩以补注地下水时,砂桩存在对灌溉水中之溶质在土壤中传输之影响.由试验结果得知当砂桩贯穿牛踏层时可增加水分入渗速率约40倍,相对的,砂桩亦加速溶质在不同土壤层间之传输速率,尤其在牛踏层下方之土壤为砂层时,其影响更为显著.因此,蓄水过程中需注意水源之品质,以避免土壤与地下水受污染.

Effects of groundwater recharge using sand piles on solute transport in fallow croplands by sand tank model

The functions of paddy fields will shift from mere production to incorporate with ecological functions. The retained water in paddy fields during fallow period can not only maintain ecological function, but also enhance soil moisture and recharge groundwater in field. In this paper, the sand tank model is used to investigate the effects of groundwater recharge with sand piles on solute transport in fallow croplands. The results show that the infiltration rate increases about 40 times with the sand piles piercing through hard pan than without sand piles. On the contrary, the sand piles also increase the solute transport rate between soil layers. The effects are more conspicuous when the sand soil exists under hard pan. Therefore, the quality of irrigation water has to be inspected during retained process to prevent the soil and groundwater from being polluted.