Department of Civil Engineering, National Taipei University of Technology, Taipei, Taiwan.
Department of Natural Resources, Chinese Culture University, Taipei, Taiwan.
Environ Monit Assess. 2021 Jan 27;193(2):91. doi: 10.1007/s10661-021-08879-5.
Soil moisture content is a key factor affecting surface evaporation in the hydrologic cycle, with application in water resources management, early drought warning system, irrigation management, and estimation of crop yield. The subject of soil moisture content has long been of interest in hydrology, agriculture, forestry, and soil mechanics engineering. The cracking of surface soil due to dryness is often used to describe the drought condition of the land based on the certain relationship between soil cracking and moisture content. This study establishes the relation between fractal dimensions of soil cracking patterns and moisture content of surface soil. Sixteen soil samples were prepared and subjected to drying under different temperature levels to crack in the laboratory. Photographs of the cracks were digitized and an algorithm for calculating fractal dimensions of cracking patterns was developed. The results demonstrated that the fractal dimensions of cracking patterns are highly correlated with the surface soil moisture content; the lower the soil moisture content, the larger the fractal dimension is. Therefore, the surface soil moisture content-fractal dimension (D-w) rating curves can be established. Once crack structures occur on surface soil, the moisture content of the surface soil can be estimated quickly and accurately by mean of remote sensing technique such as UAV together with the fractal analysis.
土壤湿度是影响水文循环中表面蒸发的关键因素，在水资源管理、旱情预警系统、灌溉管理和作物产量估算等方面有应用。土壤湿度这一主题一直是水文学、农业、林业和土壤力学工程领域关注的焦点。由于土壤干裂常常被用来描述土地的干旱状况，因此基于土壤干裂与湿度之间的某种关系，人们提出了用土壤干裂来描述土地干旱状况的方法。本研究建立了土壤干裂模式分形维数与表层土壤湿度之间的关系。制备了 16 个土壤样本，在实验室中于不同温度水平下进行干燥以产生干裂。对干裂进行拍照并开发了用于计算干裂模式分形维数的算法。结果表明，干裂模式的分形维数与表层土壤湿度高度相关；土壤湿度越低，分形维数越大。因此，可以建立表层土壤湿度-分形维数（D-w）评级曲线。一旦表面土壤出现干裂结构，就可以通过无人机等遥感技术结合分形分析，快速准确地估算表层土壤的湿度。
