Soil moisture

Soil moisture plays a key role in the hydrological cycle by distributing precipitation between evapotranspiration, runoff, and percolation. The total amount of water stored in the soil is much smaller compared to other storages (groundwater, ground ice, lakes). Nevertheless, a contribution of soil moisture to the water budget is significant, even on a global scale, due to its pivotal role in the global water cycle by controlling the water, energy, and biogeochemical cycles at the Earth's surface. The distribution of soil moisture is controlled by several factors comprising bedrock geology, topography, land use, management practices, vegetation and local climate. The estimation of soil moisture content for larger areas is a difficult task burdened with a significant amount of uncertainty. Currently, it can be addressed by three different approaches: field (or in situ) measurements, soil water balance models and most recently by the various remote sensing techniques. The correct estimation of the actual soil moisture content is important for variety of reasons ranging from the description of water fluxes among land, atmosphere and ocean and for the agricultural and water management.

Research Activities

The research activities of the Institute of Hydrodynamics are primarily focused on the elucidation of soil water regime under different land covers (spruce and beech forest, grassland) with the emphasis on differences between water deficient and water abundant periods. The special attention is paid on the determination of the evapotranspiration rate in particular experimental plots. The total evapotranspiration is represented by the sum of evaporation from interception, transpiration of plants, and evaporation from the soil surface. The percolation of water into deeper soil layers is estimated by various modelling techniques. Further, the influence of soil hydraulic properties and their spatiotemporal variability on the observed soil water regime is also investigated. Soil hydraulic properties, i.e. the ability of soil to retain and conduct water, are determined namely by the soil structure (given by the spatial organisation of solid particles – aggregates), soil texture (given by the particle-size distribution) and by the amount of organic matter. The aim of the research is to describe the abilities of soil to retain water which is necessary for the determination of the actual soil water content in the locations without field observations. The research results serve as a basis for the better prediction of floods, soil drought and for the determination of factors enabling increase of soil water retention in the landscape.