Natural water retention ponds for water management in agriculture: A potential scenario in Northern Italy

Climate change is affecting water quantity and quality, with severe impacts on agricultural production. The use of nature-based solutions to address these challenges is increasing. Natural water retention ponds have been identified as viable solutions for water management in agriculture. This paper aims to characterize water retention ponds, and to quantify their effectiveness, direct and indirect benefits, and costs. The paper analyses the case of the Lamone river catchment in Emilia-Romagna Region (Italy), characterized by large seasonal variability of water flow and availability. This is an important agricultural area that relies heavily on irrigation. Here water retention ponds are systematically applied to store water in winter, for use during the dry season. They can play a strategic role in ensuring irrigation water availability, while preserving minimum environmental flow. The paper analyses both the benefits of ponds for the water balance at sub-catchment scale, and the environmental effects produced by ponds having an ecological functionality. We develop an implementation scenario for new ponds, and we appraise the contribution of new ponds whose siting is chosen in order to maximize landscape connectivity. Their hydrological effects are evaluated under present and future climate change scenarios, showing how they may increase water availability for irrigation, while improving the river flow regime. More water for irrigation can favour additional agricultural production, while a more ecologically oriented design of ponds can favour to landscape ecological improvements. The investment costs of ponds are justified in economic terms, and the additional costs of improved design are expected to be balanced by the ecosystem services obtained. The business model required to operate this type of intervention is discussed, together with potential funding channels. We discuss two innovative incentive models based on compensation of land and production lost, and on tradable development rights that can be applied to widely support NBS implementation.