Development and Application of a Soil Moisture Downscaling Method for Mobility Assessment

摘要

Soil moisture is a critical variable for many Army activities including mobility assessments. Several methods can be used to produce soil moisture patterns at an intermediate resolution (grid cells with approximately 1 km linear dimension). However, mobility assessments require fine-resolution estimates (approximately 30 m grid cells). Thus, a method is required to downscale intermediate- resolution patterns to finer resolutions. Fortunately, fine-resolution variations in soil moisture are known to depend on various topographic attributes, and topographic data are available at fine-resolutions for almost any region on Earth. The overall objective of this project is to develop, calibrate, and apply a method to estimate fine-scale soil moisture patterns based on intermediate-resolution soil moisture estimates and the observed topographic dependence of soil moisture. The method is a conceptual model that estimates soil moisture values by assuming that the soil moisture pattern is at equilibrium and by inferring the spatial variations of vadose-zone processes from topographic characteristics. The method is calibrated using the Tarrawarra and Cache la Poudre catchments, which have extensive soil moisture datasets. It is then applied to a region of interest in Afghanistan for dry, wet, and very wet scenarios where only intermediate-resolution estimates are available.