Post a comment on the text below

4.2.2        Other relevant measures at farm and landscape level

Other farm and landscape measures can contribute to reducing pressures, such as “offline” storage, water harvesting, groundwater use and use of non conventional water resources. They are discussed separately here to highlight their potential contribution to enhance the sustainability of agriculture, if implemented with the right safeguards.

Some countries, such as France, are currently building “offline” storage schemes, i.e. reservoirs are built outside river beds in order to reduce their hydromorphological impacts. They are filled by pumping into water bodies during high flow season (winter) in rivers or shallow, unconfined groundwater, therefore lowering the direct impact of pumping on environmental flows. Storage is only used to substitute summer pumping and cannot result in an increase in irrigated areas. They must be accompanied with metering and the cancellation of the licence to abstract during seasonal low flows. Priority is given to projects regrouping several farmers and must be specifically designed to support WFD targets. Their implementation is widely debated, and further adoption will need to take into account their potentially large visual and environmental impact (i.e. affecting winter flow dynamics) (see Granjou and Garin, 2006).

Rainwater and runoff harvesting in small ponds and reservoirs (with storage capacities of 100–10,000 m³) is being promoted in many countries to increase farm resilience to droughts and reduce abstraction pressure. However, their multiplication in catchments can cumulatively lead to major modifications of hydrological regimes (Carluer et al., 2016b). Their impact on the overall water balance should be considered.

The second half of the 20^th century has also seen a major growth in the use of groundwater by agriculture, in particular in countries of southern Europe such as Spain but also in northern countries such as The Netherlands and the UK (Foster and Custodio, 2019), often contributing to increase water imbalances at catchment level (Llamas and Martínez-Santos, 2005; De Stefano et al., 2015).

There is a growing interest in more coordinated (“conjunctive”) use of surface water and groundwater, where surface water is used in wet years and groundwater in dry years, so as to maximise the availability of water during dry years (i.e. groundwater is used as an underground reservoir). Managed aquifer recharge may be used to maximise benefits from the storage capacities of groundwater bodies and better regulate groundwater–surface water exchanges. Managed aquifer recharge is increasingly used for improving supplies for drinking water purposes, but there is scope to expand use for across Europe (Sprenger et al., 2017) including by combining it with wastewater reuse schemes (Zuurbier et al., 2018). Although studies of conjunctive use have been done at local and regional level (e.g. Pulido-Velazquez et al., 2008; Guyennon et al., 2017), the potential at EU level is yet unknown.

The use of alternative water resources such as desalinated water and treated wastewater, is poorly documented, but limited available evidence suggest it is minor at European level (BIO by Deloitte, 2015). Some countries nevertheless have implemented reuse in a large scale, such as Cyprus which reuse up to 90% of its wastewater.

Greater use of non-conventional water face acceptability issues, design and technological challenges, and various financial, environmental and climate risks (Kirhensteine et al., 2016) . Furthermore, wastewater reuse should account for existing uses, including environmental needs, which have to date been dependent on the steady flow of wastewater discharges. Redirecting wastewater discharge towards reuse instead of receiving water bodies might negatively affect ecological conditions during low flow conditions; Hence not all wastewater is available for reuse and careful catchment balances are needed to assess real potential (Drewes et al., 2017).