Determination of Preferential Flow in Precipitation Infiltration Recharge
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摘要: 优先流是降水、灌溉水等入渗补给地下水的主要形式之一, 流速快, 流动路径复杂, 难以定量描述.针对优先流难以定量描述的问题, 以郑州地中渗透仪观测资料为基础, 探讨了新乡亚砂土等试筒降水入渗过程及其中的优先流补给量比例.根据土壤的水力性质、气候等资料建立不存在优先流的数值模拟模型来刻画降水入渗补给过程, 通过模拟获得的地下水入渗补给量与实测地下水入渗补给量的历时曲线, 将大于模拟值的实测值视为优先流的量及确定其在总补给量中所占的比例.结果表明, 优先流占总补给量的比例在10%~80%之间; 随着土壤粘性增加, 优先流所占比例呈增加趋势; 随地下水位埋深的增大, 优先流所占比例呈逐渐下降趋势.Abstract: Preferential flow is one of main forms of infiltration recharge from rainfall and irrigation to groundwater.It has the characteristics of rapid flow rate, complicated flow path and being very difficult to be quantified.To quantify the preferential flow in the infiltration recharge process and its percentage in total infiltration recharge, a new method has been developed based on the measured infiltration recharge of lysimeters in Zhengzhou Groundwater Balance Test Field.The numerical simulation model that can describe the piston flow in lysimeters by rechards equation was constructed and calibrated according to the soil hydraulic parameters, weather data and so on.The surplus part in the calculated flux can be regarded as the preferential flow because the preferential flow flows faster than piston flow and reaches groundwater earlier.By comparing the measured recharge flux and calculated recharge flux, the quantity of preferential flow and its percentage in total precipitation infiltration recharge can be determined.The preferential flow makes up 10%-80% in total precipitation infiltration recharge.The percentage is higher when the soil contains more clay, and the percentage is lower when the groundwater level is deeper.
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Key words:
- lysimeter /
- preferential flow /
- precipitation infiltration recharge /
- simulation modeling
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表 1 新乡亚砂土岩性颗粒分析资料
Table 1. Particle analysis of clayey loam in Xinxiang
表 2 识别后的新乡亚砂土水力参数值
Table 2. Calibrated parameters of loam in Xinxiang
表 3 不同埋深新乡亚砂土中优先流量
Table 3. Quantity of preferential flow in loam in Xinxiang
表 4 不同岩性试筒中优先流所占比例
Table 4. Percentages of preferential flow in total precipitation infiltration recharge
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