Irrigation districts play a decisive role in Portuguese agriculture and require the adaptation to the new water management paradigm through a change in technology and practices compatible with farmers’ technical know-how and economic sustainability. Therefore, improvement of water management, focusing on water savings and increasing farmers’ income, is a priority. In this perspective, an applied research study is being carried out on the gravity-fed Lis Valley Irrigation District to assess the performance of collective water supply, effectiveness of water pumping, and safety of crop production due to the practice of reuse of drainage water. The water balance method was applied at irrigation supply sectors, including gravity and Pumping Irrigation Allocation. The average 2018 irrigation water allocated was 7400 m3/ha, being 9.3% by pumping recharge, with a global efficiency of about 67%. The water quality analysis allowed identifying some risk situations regarding salinization and microbiological issues, justifying action to solve or mitigate the problems, especially at the level of the farmers’ fields, according to the crops and the irrigation systems. Results point to priority actions to consolidate improved water management: better maintenance and conservation of infrastructure of hydraulic infrastructures to reduce water losses and better flow control; implementation of optimal operational plans, to adjust the water demand with distribution; improvement of the on-farm systems with better water application control and maintenance procedures; and improvement of the control of water quality on the water reuse from drainage ditches. The technological innovation is an element of the modernization of irrigation districts that justifies the development of multiple efforts and synergies among stakeholders, namely farmers, water users association, and researchers.
This chapter aims to analyze the rice production system at the Baixo Mondego Valley to understand the main concerns. Field research and field trials were carried out to analyze rice production, marketing systems, and different irrigation alternatives. An analysis on the worries was made, and a correlational attempt was done. The results show a production system oriented by agri-environmental policies. The problems related with rice irrigation are water scarcity, environmental impacts on water quality, agroecosystems, and methane emissions. To reduce water demand, the alternate wetting and drying flooding method, and the improvement of the precise land levelling were studied on the scope of MEDWATERICE Project. About 12-14% of water saving was observed, with impact on production lower than 3.5%, allowing period of 11-19 days of dry soil, expecting positive implications for greenhouse gas emissions. Innovation in the irrigation system may help to reduce some of the farmers' concerns and help to better adapt this crop to the new needs of agriculture in terms of environmental competitiveness.
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