The green and blue crop water requirement WATNEEDS model and its global gridded outputs

Abstract

accurately assessing green and blue water requirements from croplands is fundamental to promote sustainable water management. In the last decade, global hydrological models have provided important insights into global patterns of water requirements for crop production. as important as these models are, they do not provide monthly crop-specific and year-specific data of green and blue water requirements. Gridded crop-specific products are therefore needed to better understand the spatial and temporal evolution of water demand. Here, we present a global gridded database of monthly crop-specific green (rain-fed) and blue (irrigated) water requirements for 23 main crops and 3 crop groups obtained using our WATNEEDS model. For the time periods in which our dataset matched, these estimates are validated against existing global products and satellite based datasets of evapotranspiration. the data are publicly available and can be used by practitioners in the waterenergy-food nexus to assess the water sustainability of our food and energy systems at multiple spatial (local to global) and temporal (seasonal to multi-year) scales.

Potential for sustainable irrigation expansion in a 3 °C warmer climate

“…CWR and IWR were assessed using the WATNEEDS crop water model (ref. 29 has a detailed description). WATNEEDS is a global process-based crop water model that is set up to calculate CWR and IWR for 130 primary crops (nearly 100% of global crop production).…”

“…We first identify croplands affected by green water scarcity (GWS)—croplands where the natural soil moisture regime is insufficient to sustain unstressed crop production and additional water needs to be supplemented by irrigation to boost yields ( 10 ). Second, using estimates of irrigation water requirements (IWRs) based on a crop water model ( 29 ), we identify the currently rain-fed croplands that will need to be irrigated in a 3 °C warmer climate. Third, we map presently rain-fed agricultural regions where the local surface water and groundwater resources would allow for a sustainable expansion of irrigation using monthly water storages ( Materials and Methods ).…”

Energy implications of the 21st century agrarian transition

“…Irrigation requires energy to transfer water from the withdrawal source to the field-unless the local topography allows for gravity irrigation. We use the WATNEEDS crop water model 46 to assess the energy intensity of irrigation (i.e., the irrigation energy demand per unit of area) of each land deal, considering two of the most widespread irrigation systems: sprinkler and surface irrigation (Fig. 5).…”

Scenarios of sustainable irrigation expansion in the 21st century

“…We use the data estimates of calorie production under current conditions and in the case of maximized crop production by alleviation of water limitations (called the yield gap closure, or YGC scenario). Using a global process-based crop water model 43 , Rosa et al (2018) assessed crop water requirements to reach yield gap closure, i.e. the amount of irrigation water needed to complement input from precipitation so as to ensure sufficiently high soil moisture levels and satisfy the crop evapotranspirative demand.…”