Hydrologic Balance Model Using Neutron Probe Data

Abstract

A hydrologic balance model has been developed that employs neutron probe readings for soil moisture content coupled with measured amounts of precipitation and irrigation. The major objective of the model is to estimate evapotranspiration over time periods corresponding to the frequency of neutron probe readings. Earlier versions of the model were successfully applied to determine differentials of evapotranspiration over limited horizontal distances in crop water production function field experiments. The current version of the model was specifically developed for application in a regional evapotranspiration experiment requiring model flexibility to respond to a wide range of hydrologic conditions. Example output from the model applied to the regional evapotranspiration experiment is indicated. A scheme for testing parameterization of various components of the hydrologic cycle using the model is presented.