摘要
土壤水流通量(Jw)是一个重要的水力学参数,决定着土壤渗漏、径流和化学物质的迁移过程,但缺少相应的实际技术来进行实时定位测定。本研究通过设置室内一维饱和土壤不同水流速率下的热脉冲试验,根据热脉冲技术测定的热源上下游温度变化,利用上下游最大无量纲温差法(MDTD)、上下游温度升高比率法(Td/Tu)及改进的比率法估算Jw,并检验其可靠性。结果表明,三种方法估算的Jw与通过收集出流液测定的Jw存在很好的线性关系(R2>0.99)(Jw<6×10-5 m s-1)。三种方法估算的Jw均低于出流液测定值,其中Td/Tu估算的Jw精度最高,而且计算简单,需要的参数相对较少。对于质地较粗的砂土,Td/Tu法估算的Jw较为准确,但是对于质地较细的砂质黏壤土,尤其是Jw较大时,实测值和估算值差异很大,估算误差达到20%。此外,本文也分析了热脉冲技术低估Jw的原因,为进一步发展热脉冲技术提供依据。
Soil water flux（Jw） is an important hydrological parameter which determines soil infiltration,runoff and solute transport,yet no corresponding practical techniques are available for its real-time measurement in situ.In this study,heat-pulse measurements were performed of deferent water fluxes in packed soil columns different in texture.Based on temperature changes between upstream and downstream locations from the heat-pulse probe,water flux was then calculated with the MDTD method（maximum dimensionless temperature increase difference）,and the Td /Tu method（ratio of temperature changes between downstream and upstream positions）,and a modified Td /Tu method along other known parameters.Results indicated that strong linear relationships（R20.99） existed between the estimated and the measured water fluxes（up to 6×10-5 m s-1）.Though,the three methods all down-estimated,however,the Td /Tu method was highest precise and simplest in calculation,and needed the least number of additional parameters.In coarse sand,the Td /Tu method was relatively more accurate in estimation of Jw,yet in fine sandy clay loam,especially when Jw was greater,obvious discrepancies were observed between the estimated and the measured,reaching 20%.Besides,the reason of underestimation of Jw with the heat-pulse technique is explored and presented as a basis for further development of the heat-pulse technique.
出处
《土壤学报》
CAS
CSCD
北大核心
2011年第5期947-956,共10页
Acta Pedologica Sinica
基金
国家自然科学基金项目(50479010)资助
关键词
水流通量
热脉冲技术
热传输
Water flux
Heat pulse technique
Heat transfer
