WaterCROP, an agro-hydrological model as a decision-supporting tool for irrigation water management

Water governance runs from international organizations to local consortiums through national governance. Thanks to the implementation of water policies and laws, governments are expected to ensure both (water-dependent) food and energy security without undermining environmental protection. Nowadays, agriculture accounts for 70% of the global freshwater withdrawals, and, due to the world population growth and dietary changes, this value is expected to increase. In fact, despite irrigation systems being present only in 20% of the cultivated areas, irrigated crops account for 50% of the total world’s food production. This sets the basis for local water management requirements even in generally water-rich countries. Future alterations of the hydrological cycle due to climate change are expected to further emphasize the need for water governance as they are going to affect the availability of natural water resources.

Under these conditions, an effort is required to improve national agricultural water management efficiency and to reduce agriculture's vulnerability to climactic variability. Correct water management has, in fact, the potential benefit of regulating local withdrawals from water bodies, limiting excessive use of irrigation water, and reducing crop losses due to water stress.

In this framework, agro-hydrological models can be a powerful decision-supporting tool to evaluate water requirements by agriculture at different scales. In this direction, we propose the physically-based, agro-hydrological model WaterCROP. It describes the main components of the soil-atmosphere-plant continuum (such as effective precipitation, leakage, evapotranspiration, etc.) as a function of soil, crop, and period during the growing season. The hourly temporal resolution, the spatial scales (which can span from municipal to national), and the requirement for generally accessible input-data strike a balance between highly complex and simplified models. The first ones are usually site-specific, computational-demanding hydrological models that require very detailed inputs hardly available at the national scale, while the latter, being large-scale models, provide generally too coarse results for water management decision-making.

We apply the WaterCROP model to the Italian case, showing its use to describe irrigation water-saving scenarios both for cereals crops (wheat and maize) and cash crops (vine and olives).