Waterfootprint: A Dynamic, Web-Based Tool for Agricultural System Evaluation and Regional Comparison.

The water footprint of an agricultural product is a measure of the consumptive water use required to produce a crop; it is the water volume used per unit mass of produce (gallons/lb or liters/kg).  Consumptive water use in agricultural areas results almost entirely from evapotranspiration (ET).  An important distinction in water footprinting is the separation of green water footprint and blue water footprint.  Green water use represents ET from rainfall, while blue water use represents ET of applied irrigation from a freshwater resource, groundwater or surface water.  A water footprint can be useful for comparing water-use impacts of management alternatives or for comparing water resource impacts of crops grown in different regions.  The WaterFootprint tool of AgroClimate.org simulates plant growth and water use using a modified version of the EPIC crop model (Environmental Policy Integrated Climate).  Additional water balance representation was developed to separate green and blue water footprints.  Daily rainfall and temperature data are retrieved from the nearest weather station using the GHCN-Daily dataset based on user-selected location.  Crop yield can be simulated or provided as input.  A simple user-interface enables system-specific inputs to describe management of tillage, crop selection, planting date, and irrigation.  The dynamic nature of the tool allows for comparisons between specific agricultural systems, and makes it capable of representing the variability in space and time of water footprints.  More functionality to simulate water footprints of multi-year rotations is currently under development.