Irrigation Delivery Performance Versus Environmental Externalities: A Risk Assessment and Management Perspective

This paper presents results from a research and modelling work conducted on an irrigated agricultural area of southern Italy to assess the risks of soil and aquifer degradation occurring as indirect consequence of poor irrigation delivery performance by a water supply system. The area is intensively farmed with high-value market-oriented horticulture by small land-holding growers, and is equipped with a gravity-fed piped irrigation delivery system managed by a local Water Users Organization. Investigations revealed significant aquifer salinity increase from winter to summer months, likely due to intensive groundwater pumping by farmers during peak irrigation demand periods, even though surface water is available to growers from the collective delivery system. Phenomena of seawater intrusion were documented by several research campaigns conducted on the study area in the last decades, as resulting from mining of the coastal aquifer for irrigation and touristic purposes. The environmental hazards of aquifer and soils degradation were appraised through the use of a simplified Risk Assessment procedure, identifying the risk-generating processes and assessing the overall risks significance. The stakeholders' perspective was collected through interviews to growers and delivery system operators, and used to support the risk assessment procedure. Fuzzy Cognitive Maps (FCMs) were developed and used to simulate the groundwater exploitation attitude of farmers versus water withdrawals from the collective delivery network. Some risk mitigation options were identified using dynamic analysis of FCMs to explore the likely reaction of growers' behavior in response to possible changes. Overall, the modelling tools proved to be useful in supporting public participation and representing the knowledge domain of stakeholders in making decision about water resources access, use and management.