Mellanvatten

Mellanvatten is a term used in Swedish hydrology and civil engineering to describe water that exists in the pore spaces of soil and rock at depths between the surface and deep groundwater. It covers moisture in the vadose zone and any perched groundwater that may occur above an impermeable layer. The concept helps distinguish water in the soil and near-surface environment from surface water and the deeper, saturated groundwater.

In practice, mellanvatten includes both capillary and gravitational water within the unsaturated zone, as well as any localized perched groundwater that sits above low-permeability layers. Its presence and amount depend on soil texture, rock type, vegetation cover, rainfall, and evapotranspiration. Because it is not part of the continuous surface water body and is not always fully saturated like groundwater, mellanvatten can vary considerably with seasons and weather patterns.

The concept is important for multiple applications. In construction and geotechnical engineering, the amount of mellanvatten affects foundation stability and drainage design. In agriculture and soil science, it influences soil moisture availability for crops. Hydrological models often distinguish mellanvatten from surface water and groundwater to accurately simulate water storage, transfer, and drainage in landscapes.

Measurement and assessment of mellanvatten use instruments such as soil moisture sensors, tensiometers to gauge matric potential, and groundwater monitoring wells where the vadose zone transitions to saturated conditions. The term's precise usage may vary regionally, but it generally denotes water situated between the atmosphere and deep groundwater within the near-surface environment.