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Box 4.4 Volumetric control on abstraction of agricultural irrigation

Limits on total agricultural abstraction have been adopted in some river basins in Europe. In France, the Water Law in 2006 requires abstraction caps in priority catchments and aquifers, where resources are deemed overallocated. Once the cap is set by authorities, together with users, the portion allocated to agriculture is managed by an agricultural collective management organisations called “Organismes Uniques de Gestion Collective” (OUGC). The OUGC is conceived as administrative (relay) institution to improve local knowledge of agricultural abstraction, pool individual water demands annually, define allocations between farmers and report use after the irrigation season. Policing and compliance remain in the control of public administrations. This comanagement between authorities and agricultural users has contributed to improve knowledge of agricultural abstraction in basins and aquifers and to reinforce local control on agricultural abstraction.

In Spain, user associations have also been created to manage overexploited aquifers. The management of some aquifers, such as the Mancha Oriental, present some elaborate forms of monitoring and controls on abstraction based on Earth Observation information. Farmers are required to prepare an irrigation plan specifying which crops will be irrigated and where. Based on this, the user association performs continuous earth observation to detect potential cases of over-abstraction and target field inspections. This is assisted with calibrated flowmeters on wells. This has significantly improved controls and the water table level has been stabilized.

While the French and Spanish case present advanced experiences on controlling abstraction, there are many challenges in implementation. Ideally, water permits should be reviewed to reduce the overallocation. However, historical water use rights and entitlements pre-dating the WFD may persist, and authorities usually face significant legal and political constraints in modifying them. In France for example, the definition of abstraction caps imply that agricultural extractions have to be reduced by 10 to 20% compared to historical use in most priority catchments and by over 50% in some cases. Reductions are to be achieved with no financial compensation. Ambitious reforms are needed to overcome these barriers and engage in a full and wide ranging review of existing permits.

Sources: Playán et al., 2018; Ortega et al., 2019; Rouillard and Rinaudo, 2020; Arnaud, 2020; Schmidt et al., 2020