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Water retention curve is the relationship between the water content, θ, and the soil water potential, ψ. The soil moisture curve is characteristic for different types of soil, and is also called the soil moisture characteristic. It is used to predict the soil water storage, water supply to the plants (field capacity) and soil aggregate stability.
Accumulation numbers in flat areas will be very large, so TWI will not be a relevant variable. The index is highly correlated with several soil attributes such as horizon depth, silt percentage, organic matter content, and phosphorus. [2] Methods of computing this index differ primarily in the way the upslope contributing area is calculated.
The Global Climate Observing System specified soil water as one of the 50 Essential Climate Variables (ECVs). [18] Soil water can be measured in situ with soil moisture sensors or can be estimated at various scales and resolution: from local or wifi measures via sensors in the soil to satellite imagery that combines data capture and ...
Thereby soil bulk density is always less than soil particle density and is a good indicator of soil compaction. [47] The soil bulk density of cultivated loam is about 1.1 to 1.4 g/cm 3 (for comparison water is 1.0 g/cm 3). [48] Contrary to particle density, soil bulk density is highly variable for a given soil, with a strong causal relationship ...
A relatively low rate of change indicates when macropore drainage ceases, which is called Field Capacity; it is also termed drained upper limit (DUL). Lorenzo A. Richards and Weaver [5] found that water content held by soil at a potential of −33 kPa (or −0.33 bar) correlate closely with field capacity (−10 kPa for sandy soils).
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]
The Richards equation represents the movement of water in unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. [1] It is a quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. [2]
Consolidation is the process in which reduction in volume takes place by the gradual expulsion or absorption of water under long-term static loads. [3] When stress is applied to a soil, it causes the soil particles to pack together more tightly. When this occurs in a soil that is saturated with water, water will be squeezed out of the soil.