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SWAT (soil and water assessment tool) is a river basin scale model developed to quantify the impact of land management practices in large, complex watersheds.SWAT is a public domain software enabled model actively supported by the USDA Agricultural Research Service at the Blackland Research & Extension Center in Temple, Texas, USA. [1]
Soil and Water Assessment Tool (SWAT) is a free and open source hydrology model and GIS computer simulation sponsored by the USDA. SWAT is a well known geographic hydrological model in use by many universities and government agencies around the world, and integrates with commercial products like ArcGIS .
Pores (the spaces that exist between soil particles) provide for the passage and/or retention of gasses and moisture within the soil profile.The soil's ability to retain water is strongly related to particle size; water molecules hold more tightly to the fine particles of a clay soil than to coarser particles of a sandy soil, so clays generally retain more water. [2]
Water moves in soil under the influence of gravity, osmosis and capillarity. [7] When water enters the soil, it displaces air from interconnected macropores by buoyancy, and breaks aggregates into which air is entrapped, a process called slaking. [8] The rate at which a soil can absorb water depends on the soil and its other conditions.
Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually occurs two to three days after rain or irrigation in pervious soils of uniform structure and texture.
Download as PDF; Printable version; In other projects ... move to sidebar hide. Soil water can refer to: Soil#Soil moisture - water in soil; Soil water (retention) ...
It is also known as available water content (AWC), profile available water (PAW) [2] or total available water (TAW). The concept, put forward by Frank Veihmeyer and Arthur Hendrickson, [3] assumed that the water readily available to plants is the difference between the soil water content at field capacity (θ fc) and permanent wilting point (θ ...
Flows through the unsaturated zone that couple surface water to soil moisture and groundwater can be upward or downward, depending upon the gradient of hydraulic head in the soil, can be modeled using the numerical solution of Richards' equation [2] partial differential equation, or the ordinary differential equation Finite Water-Content method ...