Nature-based solutions - Sustainable water management

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Constructed Wetlands for agricultural runoff

Agricultural fields give a strong contribution to water bodies (rivers, lakes, aquifers) pollution, conveying pollutant loads with rainfall runoff.

The agricultural pollutant load generates from fertilizers and pesticides, but also from organic loads, especially in flat agricultural areas (e.g. Po Valley) where the land application of manure is a common practice. Constructed wetlands, as well as other nature-based solutions such as buffer strips and wooden buffer zones, are optimal solutions to reduce diffuse pollution, which cannot be managed with conventional technological treatment techniques (see also: constructed wetlands for nutrient removal)


  • diffuse pollution interception with extensive nature-based solutions
  • water quality improvement
  • possibility of wetland restoration with high naturalistic value
  • possibility to combine water pollution control and flood mitigation with multipurpose green infrastructure

More information

Agriculture has been identified as a significant source of pollution of superficial and underground waters. The effects of the agricultural pollution are numerous and include sediments contamination and deposition, pesticides residues, eutrophication of superficial waters and degradation of down-stream rivers. These effects are caused by diffused pollution sources (NPS, Non-Point Sources ), that are considered as one of the major causes of the problems of the water bodies.

Applications in agriculture of fertilizers and pesticides have been dramatically increased starting from the mid-1960's, and the agro-chemical contamination of superficial and underground water has come to be a serious environmental problem. Nitrogenous compounds and pesticides represent the principal problem, due to the effects on human health and ecosystems, and to their wide utilization. It has to be noted that generally quite the 50% of nitrogenous fertilizers applied to the fields is lost in the drainage water, mostly in the form o nitrates NO3. Therefore, all these pollutants reach in great quantities the hydrographical network.

It is unlikely that these problems can be solved just by the management of the situation based on chemical treatments. Moreover, the diffuse character of the problem makes environmentally and economically unsuitable a conventional technological approach.

On the contrary, an approach based on extensive treatments realized by natural depuration techniques has proved itself to be efficient and able to promote the restoration of the agricultural ecosystem.

From this perspective, the small dimensions of artificial wetlands (like an order of magnitude, the requested surface is about the 5% of the surface of the served agricultural field) together with the high treatment power suggest that constructed wetlands can be scattered in the agricultural land, assuring the treatment of the diffuse pollution. In this way, they can also contribute to create a higher complexity of the agricultural ecosystem, in terms of landscape, biodiversity and habitats for the wildlife. Considered that constructed wetlands can receive also eventual organic loads (for example connected to rain events), they can represent a powerful instrument with which the agriculture can even create benefits for the community: agriculture could actively participate in the improvement of the quality of water, in particular, and of the environment in general.

The experience of the South Florida Everglades Restoration Project is among the most interesting in the field of agricultural runoff treatment, in which hundreds of cropland were converted in wetlands to protect the Everglades swamp from eutrophication.(

An Italian example is the Life Aqua project, in which a technical manual was written on the use of constructed wetland for treatment of agricultural runoff and swine wastewater.

pdf factsheet: Life Aqua (in Italian)