| 基于溴离子示踪的干旱地区潜水蒸发规律研究 |
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| 作者单位： | ;1.武汉大学水资源与水电工程科学国家重点实验室;2.内蒙古河套灌区义长灌域管理局 |
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| 摘 要： | 【目的】定量研究干旱地区潜水蒸发规律。【方法】以河套灌区义长灌域为研究区,采用人工示踪剂溴离子示踪法研究了盐荒地潜水蒸发规律,通过获取试验期间研究区内6个试验点不同土层深度土壤溴离子质量浓度、含水率、含盐量数据,分别利用化学示踪法、水均衡法及经验公式法计算了潜水蒸发量,对比了3种方法的结果及适用性并分析了潜水蒸发量与不同土质、不同土壤含盐量的关系。【结果】利用溴示踪方法得到研究区7月6日—8月18日潜水蒸发总量为35.20 mm,平均潜水蒸发系数为0.28;水均衡法所得结果为32.29 mm,与示踪法所得结果的相关系数达到0.96;由于研究区域土壤异质性强,且干旱区水文地质资料较为匮乏,经验公式法参数获取难,水均衡法所需实测资料多,在研究区适用性不高。而溴示踪法操作简单、经济实用,适用性强,较其他2种方法更为可靠。研究区潜水蒸发量随黏粒质量分数的增加而不断减小,二者之间的相关系数达到了0.80,尤其当土壤中存在黏土夹层时,将降低潜水蒸发速率。【结论】研究区土壤含盐量的变化量随潜水蒸发量增加而不断增加,表明盐荒地强烈的蒸发作用是造成耕地与荒地水盐交换的驱动力,直接影响灌区的水循环过程。
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| 关 键 词： | 溴离子示踪法 潜水蒸发 土壤质地 干旱区 河套灌区 |
Using Bromide Tracer Method to Analyze the Evaporation Rule of Phreatic Water in Arid Area |
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| Institution: | ,The State Key Laboratory of Water Resource and Hydropower Engineering Science,Wuhan University,Yichang Irrigation Bureau of Hetao Inner Mongolia |
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| Abstract: | 【Objective】The objective of this study is to quantitatively analyze the rule of phreatic evaporation in arid area.【Method】Bromide tracer experiments were conducted at six field sites in the fallow areas of Hetao Irrigation District in attempts to estimate phreatic evaporation according to the peak of tracer's concentration in soil profile. The results of bromide tracer experiments were compared with the water balance method and empirical equations methods. Meanwhile, the observation of soil water content and soil salt content at different soil depth for each experimental sites were collected to illustrate its effect on phreatic evaporation.【Result】The accumulative phreatic evaporation estimated from the tracer experiment was 35.20 mm with the average evaporation rate being 0.28 for the period of 6 July to 18 August. The result was close to 32.29 mm that calculated from water balance analysis and the correlation coefficient between the two was 0.96. Considering the strong spatial heterogeneity of soil properties in study sites and the lack of hydrogeological data in arid area, results generated from water balance analysis and empirical equation methods were less reliable since the parameters were hard to be determined with limited data. Overall, the bromide tracer method was a simple and convenient way for the practical application and more reasonable than the two other traditional methods. The accumulative phreatic evaporation decreased as the clay content of soil increased with the correlation coefficient of 0.80, especially when there was a clay-layered soil, the rate of phreatic evaporation would drop significantly.【Conclusion】The soil salt content increased with the increase of phreatic evaporation, indicating that the high evaporation demand is the driving force for water and salt exchange from the croplands to the fallow areas, which directly affects the water cycle process in irrigation areas. |
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| Keywords: | bromide tracer method phreatic evaporation soil properties arid area |
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