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Observational Research on the Relation between Evaporation, Precipitation and Salinization in a Semi-Arid Area in Western Australia

西澳大利亚半干旱地区蒸发、降水与盐碱化关系的观测研究

基本信息

批准号：
12574004
负责人：
SHIMOJIMA Eiichi
金额：
$ 6.98万
依托单位：
Daido Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In order to explore the relation between evaporation and salinization in semi-arid areas in Western Australia, in CSIRO's Yalanbee experimental site in Bakers Hill, hydrological and meteorological observations were undertaken from October 2000 to March 2003. Also, as intensive observations, profiles of soil-water content and chemical concentration were sometimes examined via a direct soil sampling, and to evaluate evaporation rate, measurements of water vapor density in soil and vapor flux at the ground via a dome evaporation experiment were undertaken.Salinization was markedly advanced in dry season and salt crust 5mm thick was formed on the ground surface. In wet season (annual rainfall : 400 mm), degree of that salinization was lowered by rain-infiltration and rising of water-table but its concentration was the same order of magnitude as the sea-water. Dominant ions of soil-water were Cl, Na^+ and Mg^<2+>. Solute concentration such as Cl- observed near ground surface showed an upper bound against a specific water content there. That bound is constant (saturated value) for mass wetness (M) less than 0.12, while for M>0.12, the value decreased exponentially.In summer, vapor density in soil was detected to increase linearly with depth in a zone shallower than 5 cm but its slope changed discontinuously around the ground surface. This may be caused by a significantly larger resistance of the crust. Vapor flux calculated using that linear line was more or less consistent with that through the dome experiment.Continuous data for two years obtained through the weather observation using VAISALA MAWS 101 and 201, could be applied to estimation of heat budge and evaporation. It was found that reflection (albedo) of solar radiation on the ground surface varied seasonally and the salinization affected the heat balance via the variation in the albedo.

为了探讨西澳大利亚半干旱地区蒸发与盐碱化之间的关系，2000年10月至2003年3月在澳大利亚科学与工业研究组织位于贝克山的Yalanbee实验场进行了水文和气象观测。此外，作为密集观测，有时通过直接土壤取样来检查土壤含水量和化学浓度的剖面，并通过圆顶蒸发实验来测量土壤中的水汽密度和地面上的水汽通量以评估蒸发速率。在丰水期（年降雨量400 mm），雨水入渗和地下水位上升使土壤盐渍化程度降低，但其浓度与海水浓度在同一数量级。土壤水的主要离子为Cl、Na^+和Mg^<2+>。溶质浓度，如Cl-观测近地表显示了一个上限对特定的水含量有。当质量湿度（M）小于0.12时，土壤水分饱和度为常数（饱和值），而当M>0.12时，土壤水分饱和度呈指数下降趋势，夏季土壤水分密度在浅于5cm的区域内随深度线性增加，但在地表附近其斜率呈不连续变化。这可能是由于地壳的电阻明显较大造成的。利用该直线计算的水汽通量与穹顶实验结果基本一致，利用VAISALAMAWS 101和201气象观测仪连续两年的观测资料，可用于估算热量收支和蒸发量。结果表明，地表太阳辐射反射率具有明显的季节性变化，盐渍化通过反射率的变化影响地表的热量平衡。