Development of Regional Soil Water Retention (SWR) Characteristics

The unsaturated soil hydraulic properties may be considered the key factors governing the partitioning of rainfall and irrigation into soil water storage, evapotranspiration, and deep drainage. The understanding of regional parameters of soil water retention process with the most appropriate model is necessary for better understanding of water movement and supply of water for irrigation. In the present study, an attempt has been made to develop at-site and regional analytical models for computation of soil water retention curves for different soils in two adjoining commands of Benisagar and Rangawan reservoirs in Madhya Pradesh (India). The soil samples from seventeen different sites considering uniform distribution and all predominant soils were collected and analyzed for the determination of soil water retention at different pressures. The at-site and regional parameters of soil water retention (SWR) models suggested by Brooks and Corey (1964), Van Genuchten (1980), Durner (1994), Kosugi (1996), and Seki (2007) have been applied in the study to determine at-site and regional parameters. The performance of these models was evaluated using different statistical criteria including root mean square error (RMSE), coefficient of determination (R 2), adjusted coefficient of determination \(R_{\text{adj}}^{2}\), and also the graphical representation. The soils in the study area can be divided into two distinct groups on the basis of simple graphical representation of SWR curves. The at-site and regional analysis concluded that SWR model suggested by Durner (1994) with different parameters may be considered the best-fit model for at-site and regional analysis of both soil groups (SG-1 and SG-2) in the study area.