基于混沌理论的非饱和土含水率预测

Prediction of unsaturated soil moisture content based on chaos theory

针对无资料区土体含水率数据难以获取的问题,提出了一种基于卫星反演-相空间重构-非饱和入渗计算的组合方案,以研究区110 d土体表层含水率为基础,预测未来100 d无资料时段土体表层及内部含水率分布规律。计算结果表明:研究区含水率时间序列具备混沌特征,可由一维时间序列拓扑为一个嵌入维数m=5,迟滞τ=10的相空间,由该相空间预测的土体表层含水率在验证期最小相对误差为0.7%,最大相对误差为2.4%,在预测期最小相对误差为2.2%,最大相对误差为8.3%,均满足工程需求,因此将其用于后续非饱和入渗计算的边界条件是真实有效的。该方案具有动力学特性和物理力学意义,可为无资料地区土体含水率估计借鉴。

To address the problem of difficulty in obtaining soil moisture content data in no data areas,we proposed a combination scheme based on satellite inversion,phase space reconstruction,and unsaturated infiltration calculation.Based on the soil moisture content of the 110-day surface layer in the study area,the distribution law of soil moisture content of the surface layer and internal part in the next 100-day no data period was predicted.The calculation results show that the time series of soil moisture content in the study area has chaotic characteristics,which can be topologically stretched to a phase space with embedding dimension m of 5 and delayτof 10.The minimum relative error of the soil surface moisture content predicted by this phase space during the validation period is 0.7%,the maximum relative error is 2.4%,the minimum relative error during the prediction period is 2.2%,and the maximum relative error is 8.3%,all of which meet the engineering requirements.Therefore,it is used as the boundary condition for subsequent unsaturated infiltration calculation,and the result is realistic and effective.Compared with traditional studies,the prediction scheme proposed in this paper has dynamical characteristics and physical-mechanical meanings,which can provide a new reference for soil moisture content estimation in no data areas.