Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity

Knowledge of the physics of soil water movement is crucial to the solution of many problems in watershed hydrology, for example, the prediction of run-off and infiltration following precipitation, the subsequent distribution of infiltrated water by drainage and evaporation, and estimation of the contribution of various parts of a watershed to the ground water storage. Mathematical models of hydrologic and agricultural systems require knowledge of the relationships between soil moisture content (θ), soil water pressure (h) and unsaturated hydraulic conductivity (K). Sustained research effort towards the parameterisation of K(h) and h(θ) has resulted in the development of several laboratory, field and theoretical methods. This study involved field and laboratory determination of soil moisture characteristics along the Hindon river in its upstream reach. The soils in this area are mainly sand, loamy sand, sandy loam and silt loam. A total of 37 soil samples were collected from 13 sites in 24 km upstream reach of Hindon river. Extensive laboratory measurements were made for each soil sample. Saturated hydraulic conductivity was measured through ICW Permeameter in the laboratory. Retention curve data were obtained through pressure plate apparatus. These have been used to develop an empirical relationship to derive the approximate soil moisture retention curve at the places in upper part of Hindon river basin where only saturated hydraulic conductivity data are available.