WaterCROP

Introduction

WaterCROP is a high resolution crop water footprint model, originally developed by Tuninetti et al. (2015), which evaluates the water footprint of multiple crops at the spatial resolution of 5 × 5 arc min. Originally introduced in Tuninetti et al. (2015) and written in the Matlab scientific computing programming language, WaterCROP performs separated water footprint computations by rainfed and irrigated production conditions and by growing season.

WaterCROP performs spatially-explicit estimates of daily crop-specific actual evapotranspiration (ETa,j) that a crop consumes via evapotranspiration throughout the growing season. For rainfed production, WaterCROP computes the water stress coefficient (ks,j) through a daily steady state water balance. In this case, every time water from precipitation is not sufficient for optimal evapotranspiration, the crop becomes stressed and the water stress coefficient drops below 1. For irrigated production, the model assumes that the crop receives all the water required to optimally evapotranspire via irrigation, even when water is not available from precipitation. Hence, the water stress coefficient is equal to 1 throughout the growing period. Taking the sum of the daily ETa,j values for the entire growing season gives the annual actual evapotranspiration (ETa) estimate for a crop in a grid cell. Therefore, ETa is evaluated over different time intervals and for each study crop, thus providing multiple scenarios of crop water requirement. Furthermore, WaterCROP computes the green (ETRa,g and ETIa,g) and blue (ETIa,b) shares of the crop actual evapotranspiration over the growing period, in order to evaluate the distinct contributions of precipitation (green) and irrigation (blue) water to the crop water footprint. Thus, the crop water footprint is provided as disaggregated in its green (uWFg), blue (uWFb), rainfed (uWFrf), irrigated (uWFirr) components and it is evaluated both in volume (m3) (WF) and per unit of production (m3·ton-1) (uWF).

Model structure

M-LED has two modules:

1. Main module (estimation of crop-specific actual evapotranspiration)
2. Irrigation requirements module (...)

• WaterCROP1_ETactual.m is...

Here, in line x the working directory (i.e. the folder path containing the cloned Github repository of WaterCROP should be manually inputted.

Additional manual parameters include the ...

• WaterCROP2_Irrigation_requirements.m is...

Input data and scenarios

WaterCROP accomodates 5 arc minute (1/12°; ∼ 10 km) input data and crop-specific information. Precipitation and reference evapotranspiration data are required as input data to the model, as well as crop yields (ton·ha-1) and harvested areas (ha), crop coefficients, water stresss coefficient, planting date, length of growing period, soil available water content, root zone depth and the depletion fraction.

The ETa,j estimate is equal to the product of: the daily water stress coefficient (ks,j), that is a proxy for the daily water deficiency in the unsaturated soil layer; the daily crop coefficient (kc,j), that integrates the effects of crop height, crop-soil surface resistance, and albedo of the crop-soil surface; and the daily ET0 from a hypothetical well-watered grass surface with fixed crop height, albedo and canopy resistance

Running the model

Analysing the outputs

Runtime, frequent issues, and FAQs

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Preparing a new country analysis

Designing a new scenario