Soil physical and hydraulic properties in the Donato stream basin, RS, Brazil. Part 2: Geostatistical simulation

ABSTRACT Geostatistical simulation has been the most promising and used technique for the analysis of uncertainties of soil physical and hydraulic properties, with high spatial heterogeneity. This study carried out a stochastic analysis of saturated hydraulic conductivity (Ksat) and soil water retention curve parameters in the Donato stream basin, located in the municipality of Pejuçara, in the state of Rio Grande do Sul, Brazil, with geographic coordinates between 28º 25’ 34” S and 53º 40’ 30” W, and 28º 24’ 50” S and 53º 41’ 30” W, 590 m of altitude. Soil samples were collected during the period from August to November of 2012. Sequential Gaussian simulation technique was used to generate 100 random fields of each variable. The results showed great uncertainties for Ksat and the parameter α of the soil water retention curve. The uncertainties between the percentiles 5 and 95% for Ksat indicated values from 24 to 44 cm d-1, and for the parameter α, the uncertainties could be estimated from 0.622 to 1.122 cm-1.

摘要：地质统计模拟是针对具有高度空间异质性的土壤物理与水力特性开展不确定性分析的最具应用前景且应用广泛的技术。本研究针对位于巴西南里奥格兰德州佩茹萨拉市的多纳托河流域开展饱和导水率（saturated hydraulic conductivity，Ksat）与土壤持水曲线参数的随机分析，该流域地理坐标范围为南纬28°25′34″、西经53°40′30″至南纬28°24′50″、西经53°41′30″，海拔590米。研究于2012年8月至11月期间采集土壤样品，并采用序贯高斯模拟（Sequential Gaussian simulation）技术为每个变量生成100组随机场。结果表明，饱和导水率（Ksat）与土壤持水曲线参数α均存在显著不确定性：饱和导水率的5%~95%分位数区间对应的取值范围为24~44 cm·d⁻¹，参数α的不确定性范围则为0.622~1.122 cm⁻¹。