Effect of Alternate Wetting and Drying (AWD) and Other Irrigation Management Strategies on Water Resources in Rice-Producing Areas of Northern Italy

Abstract

In rice areas with shallow aquifers, an evaluation of alternative irrigation strategies should include the interactions between irrigation and groundwater recharge and reuse, which influence the overall irrigation efficiency. A modelling system composed of three sub-models within a MATLAB framework (a physically based, semi-distributed agro-hydrological model and two empirical models, the former for the channel network percolation and the latter for the groundwater level) was applied to a 1000 ha rice district in the Padana Plain, Italy. The calibrated framework estimates the daily time series of the water supply needed and of the groundwater level for a given irrigation management, based on the inputs provided (agro-meteorology, crop data, soil data, irrigation practices, groundwater table depth upstream of the study area). Five irrigation management strategies, relevant to the area, were compared: (i) wet seeding and continuous flooding (WFL), (ii) wet seeding and alternate wetting and drying (AWD), (iii) dry seeding and delayed flooding (DFL), (iv) dry seeding and fixed-turn irrigation FTI), (v) early dry seeding and delayed flooding (DFLearly). Due to economic advantages, dry-seeded techniques (DFL, FTI) are replacing the traditional WFL in northern Italy. Simulations show that dry seeding leads to a drastic decrease of the water table in April/May, reducing the overall irrigation efficiency of the area, and that DFL (widely adopted in the area) also causes a spike in rice irrigation needs in June when other crops increase their water demand, exposing the area to water scarcity. All the cited management strategies are assessed in the paper and AWD turned out to couple smaller irrigation needs (from June onwards) compared to continuous flooding techniques with a maintenance of the groundwater recharge, especially in the first part of the irrigation season, thus being a recommendable rice management alternative for the study area.

A bibliometric analysis of scientific literature on alternate wetting and drying (AWD)

“…Additionally, AWD research is exploring innovative areas such as the impact of AWD on organically produced rice (Islam et al 2020) and the use of modelling techniques to extrapolate findings from individual experiments to broader geographic areas (Shekhar et al 2020(Shekhar et al , 2021Gilardi et al 2023). The economic sustainability of AWD adoption is also a growing focus of study (Alauddin et al 2020;Hao et al 2022;Poddar et al 2022).…”

“…The economic sustainability of AWD adoption is also a growing focus of study (Alauddin et al 2020;Hao et al 2022;Poddar et al 2022). Moreover, AWD research is extending beyond traditional regions like Asia, the USA, and Australia to places like the Mediterranean basin (Monaco et al 2021;Gharsallah et al 2023;Gonçalves et al 2022;Gilardi et al 2023), where AWD is being evaluated as a viable technique to address local issues while maintaining traditional gravity irrigation systems.…”

Effects of different irrigation patterns on paddy field environment and rice growth in non-water-retaining areas

“…Water scarcity restricts socio-economic development [18] , and many scholars have contributed to the increase in water use e ciency in paddy elds [19] . Therefore, alternating irrigation has gradually attracted the attention of scholars, and the regional implementation scheme has been veri ed [20] , which can improve water use e ciency and reduce greenhouse gas emissions [21] . Xu Ran [22] designed three irrigation modes of long-ood irrigation, mild alternating wet-drying irrigation, and severe alternating wet-drying irrigation to study rice yield, and the results showed that mild alternating wet-drying irrigation could signi cantly increase rice yield; Ye Xiumei [23] designed three intermittent irrigation modes of regular irrigation, 3~5 days, and 7~9 days to explore the irrigation methods suitable for direct seeding rice, and the results showed that 7~9 days intermittent irrigation was more suitable; Sun Xuemei [24] designed moist irrigation, controlled irrigation, The results showed that the optimal irrigation system was better for controlled irrigation.…”