Conjunctive Water Use to Control Waterlogging and Salinization

Abstract

A conjunctive‐use model is developed to maximize water user's return under limited and dynamic water supply for long‐term conditions. Salt distribution in the crop root zone is modeled and its effect on crop yield is also taken into account in the model. The main objective of this conjunctive‐use study is to find the optimal ground‐water extraction for stabilizing the water table at specific depths below land surface, while at the same time supplementing the surface irrigation supply. Concepts of limited and stressed irrigation are used to maximize net return. A daily crop water stress index is used to quantify crop yield reduction due to water stress over the growing season of a crop. Yield reduction due to salinity is calculated from the weighted average salinities (electrical conductivity) of applied waters. Salt distribution and transport in crop root zone are modeled using the physical soil properties and mass balance.