The protection of surface water bodies is indispensable for the good management and balance of the agricultural system and the territory as a whole. A good strategy for irrigation practice and for the protection of water quality, besides being indispensable for the permanence of lowland agriculture, entails a series of direct and indirect benefits on environmental and territorial dynamics. Social and environmental benefits that must be precisely identified and compensated. These are indirect services, better known in the economic discipline as positive externalities, i.e. the « favourable effects (benefits) that, unremunerated, accrue to one or more subjects thanks to the performance of an activity by a third party ». These favourable effects, since they do not have the character of an exchangeable good in a free market, cannot be directly monetised through the classic supply-demand relationship, but can be assessed through other established methods in environmental economics. These methods are based on estimating the indirect value attributed by the community to the environmental and social services that agriculture provides.
The permanence of a widespread hydraulic network and the constant presence of water resources even during drought seasons is fundamental for the overall resilience of the lowland territory, especially in a phase of climate change and increasing cementification such as the current one. According to the scientific literature, the main positive effects that the permanence of irrigation practice makes available to the community as a whole are:
- Direct return of the water resource to the natural cycle, without purification costs;
- Continuous and widespread groundwater recharge, thus counteracting subsidence phenomena and salt wedge rise;
- Dilution and phytodepuration, through the passage of water in the grassed channels, of any effluents and suspended materials from urban drains or from first rainwater;
- Maintaining an acceptable level of moisture in the surface layer of soils, with the presence of a fertile vital humus and counteracting increasing desertification, especially in structurally arid or sub-arid areas;
- Maintenance of the natural ecosystem and its biodiversity thanks to the flora and fauna present in the artificial hydraulic network;
- Preservation of the historical rural landscape (through the permanence of traditional irrigated crops) and the resulting identity-cultural link between citizens and the land;
- Permanence of viable agriculture, a fundamental element of economic and social stability and soil preservation.