Sediment thickness and bedrock topography are vital for the terrestrial hydrosphere. In this study, we estimated sediment thickness by using information from digital elevation models, geological maps, and public databases. We discuss two different approaches: First, the horizontal distances to the nearest bedrock outcrop were used as a secondary function in kriging and cokriging. Second, we applied Poisson's equation to estimate the local trend of the sediment thickness where bedrock outcrops were used as boundary conditions. Differences between point observations and the parabolic surface from Poisson's equation were minimized by inverse modelling. Ordinary kriging was applied to the residuals. These two approaches were evaluated with data from the Øvre Eiker, Norway. Estimates derived from Poisson's equation gave the smallest mean absolute error, and larger soil depths were reproduced better if the local trend was included in the estimation procedure. An independent cross-validation was undertaken. The results showed the best accuracy and precision for kriging on the residuals from Poisson's equation. Solutions of Poisson's equation are sensitive to the boundary conditions, which in this case were locations of the bedrock outcrops. Bedrock outcrops are available for direct observations; hence, the quality of the estimates can be improved by updating input from high-resolution mapping.

沉积物厚度和基岩地形对陆地水圈至关重要。在这项研究中，我们使用来自数字高程模型、地质图和公共数据库的信息来估计沉积物厚度。我们讨论两种不同的方法：首先，到最近的基岩露头的水平距离被用作克里金法和协同克里金法的次要函数。其次，我们应用泊松方程来估计以基岩露头为边界条件的沉积物厚度的局部趋势。点观测值与泊松方程抛物面之间的差异通过逆向建模最小化。对残差应用普通克里金法。这两种方法使用来自挪威 Øvre Eiker 的数据进行了评估。来自 Poisson' 的估计值 s 方程给出了最小的平均绝对误差，如果在估计过程中包括局部趋势，则可以更好地再现更大的土壤深度。进行了独立的交叉验证。结果表明，对泊松方程的残差进行克里金法的准确度和精度最高。泊松方程的解对边界条件敏感，在这种情况下，边界条件是基岩露头的位置。基岩露头可用于直接观察；因此，可以通过更新高分辨率映射的输入来提高估计的质量。结果表明，对泊松方程的残差进行克里金法的准确度和精度最高。泊松方程的解对边界条件敏感，在这种情况下，边界条件是基岩露头的位置。基岩露头可用于直接观察；因此，可以通过更新高分辨率映射的输入来提高估计的质量。结果表明，对泊松方程的残差进行克里金法的准确度和精度最高。泊松方程的解对边界条件敏感，在这种情况下，边界条件是基岩露头的位置。基岩露头可用于直接观察；因此，可以通过更新高分辨率映射的输入来提高估计的质量。