A Comprehensive Modelling Approach to Assess Water Use Efficiencies of Different Irrigation Management Options in Rice Irrigation Districts of Northern Italy

Abstract

European rice production is concentrated in limited areas of a small number of countries. Italy is the largest European producer with over half of the total production grown on an area of 220,000 hectares, predominantly located in northern Italy. The traditional irrigation management (wet seeding and continuous flooding until few weeks before harvest—WFL) requires copious volumes of water. In order to propose effective ‘water-saving’ irrigation alternatives, there is the need to collect site-specific observational data and, at the same time, to develop agro-hydrological models to upscale field/farm experimental data to a spatial scale of interest to support water management decisions and policies. The semi-distributed modelling system developed in this work, composed of three sub-models (agricultural area, groundwater zone, and channel network), allows us to describe water fluxes dynamics in rice areas at the irrigation district scale. Once calibrated for a 1000 ha district located in northern Italy using meteorological, hydrological and land-use data of a recent four-year period (2013–2016), the model was used to provide indications on the effects of different irrigation management options on district irrigation requirements, groundwater levels and irrigation/drainage network efficiency. Four scenarios considering a complete conversion of rice irrigation management over the district were implemented: WFL; DFL—dry seeding and delayed flooding; WDA—alternate wetting and drying; WFL-W—WFL followed by post-harvest winter flooding from 15 November to 15 January. Average results for the period 2013–2016 showed that DFL and WDA would lead to a reduction in summer irrigation needs compared to WFL, but also to a postponement of the peak irrigation month to June, already characterized by a strong water demand from other crops. Finally, summer irrigation consumption for WFL-W would correspond to WFL, suggesting that the considered winter flooding period ended too early to influence summer crop water needs.

Editorial—Managing and Planning Water Resources for Irrigation: Smart-Irrigation Systems for Providing Sustainable Agriculture and Maintaining Ecosystem Services

“…In this Special Issue, there are five papers published in this category. Mayer et al (2019) [4] developed an agro-hydrological modelling framework based on three sub-models (one for the agricultural areas, one for the groundwater zone, and one for the channel network) to investigate the water use efficiency in rice areas of northern Italy at the irrigation district scale. Once calibrated for a district of 1000 ha using meteorological, hydrological and land-use data of a four-year period, the model was used to assess four different irrigation management scenarios: (1) wet seeding and continuous flooding until few weeks before harvest (WFL), (2) dry seeding and delayed flooding (DFL), (3) alternate wetting and drying (WDA), and (4) WFL followed by post-harvest winter flooding (WFL-W).…”

On the effects of winter flooding on the hydrological balance of rice areas in northern Italy

“…1.1, = 0.6 (Mayer et al, 2019). Rice growth stages (ini, dev, mid, end;Allen et al 1998) were registered by the farmer in the farm diary (site E) or obtained through the processing of ESA-Sentinel2 data (site Z; Facchi et al, 2020).…”

“…Some Authors reported that winter flooding may improve the availability of soil moisture in early spring (Taghavi et al, 2015), which could be useful for crop production. Despite this, Mayer et al (2019) simulated different irrigation management scenarios through a surface water-groundwater modelling tool applied to an irrigation district of 1000 ha in northern Italy, and highlighted that the winter flooding of rice fields adopted in the district was carried out too early in the season (from November 15 th to January 15 th ) to be able to influence soil moisture and groundwater levels at the beginning of the agricultural season (end of April-beginning of May). The Authors hypothesized that winter flooding needs to be more prolonged in order to maintain a higher water table at the beginning of summer, which would allow to increase the irrigation efficiency of rice during the cropping season.…”

Rice cultivation in Italy under the threat of climatic change: Trends, technologies and research gaps

“…Climate change and price unpredictability represent severe challenges for Italian producers and agricultural companies, forced to adapt their production processes to the needs of the globalized world (Mayer et al, 2019). At present, no increase of the rice cultivation area in Italy is expected in the near future, whereas, in contrast, a decrease might probably occur if the rice price goes down, or production is affected by globalization dynamics (Venturini, 2016).…”