Présentations Colloques

Oral Presentation
Session 6.02: Treated WasteWater REUSE for groundwater recharge: addressing the challenge
Enric Queralt
The Llobregat aquifer in the water cycle management of Barcelona (Spain)
The Low Llobregat and delta aquifer, close to Barcelona, is a key element for the urban and industrial water supply of Barcelona Metropolitan Area. The water demand of the area is historically very high relative to the small and highly variable water resources under the Mediterranean climate conditions. Since 1955, the joint use of surface- and groundwater has improved the guaranty of availability. In 1966 started a water transfer to Barcelona from the river Ter, to the North. Later, in 2008 a waste water reclamation plant and in 2009 a seawater desalinization plant were incorporated to the water system. In addition, the relation between the different water sources has been favoured by means of artificial recharge, which is also relevant to prevent groundwater quality degradation. Since 1950 the scarification of a strecht of the river bed to reduce siltation allows increasing water river infiltration into the aquifer. Since 1969 a storage and recovery (ASR) well system is used to recharge treated water river. Since 2007, to compensate for infiltration area loss due to new civil works, a recharge pond infiltrates river water or reclaimed water. Finally, in 2007 a hydraulic barrier was constructed to inject advanced treated reclaimed water to halt seawater penetration into the deep delta aquifer. In all cases, an additional goal is to achieve the environmental objectives derived from the European Water Framework Directive because the groundwater body in the Low Llobregat is in bad state. A protocol defines how and when these techniques of recharge are applied. Normally the decision depends on water availability and the threshold values of quality of the water source and on the piezometric level. The cooperation between different partners has been and is the key for the water cycle management.