Online Drought Indicators and Indices

Soil Water Storage (SWS)


Index Name: Soil Water Storage (SWS)

Ease of use: Red

Origins: Unknown – producers have been trying to measure soil moisture accurately since the beginning of agriculture.

Characteristics: Identifies the amount of available moisture within a plant’s root zone, which depends upon the type of plant and the type of soil. Precipitation and irrigation both affect the results.

Input parameters: Rooting depth, available water storage capacity of the soil type and maximum soil water deficit.

Applications: Used mainly for monitoring drought in agricultural contexts, but can also be a component in drought conditions affecting water availability.

Strengths: Calculations are well known and simple to follow, even using defaults. Many soils and crops have been analysed using this method.

Weaknesses: In areas where the soils are not homogeneous, there may be large changes in small distances.

Resources: Calculations and examples are provided in the reference below.

References: British Columbia Ministry of Agriculture, 2015: Soil Water Storage Capacity and Available Soil Moisture. Water Conservation Fact Sheet.

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