p. 213-255 | Food security and water security in the Mediterranean are intrinsically linked and are facing similar challenges. Food security is threatened mainly by the high dependency of Mediterranean countries on food imports, making them vulnerable to external pressures such as volatile food prices. From a nutritional standpoint, the number of overweight and obese people has increased as a result of the traditional Mediterranean diet being abandoned. Water security has degenerated due to the deterioration of internal freshwater resources, both in terms of water quantity and quality, with a high dependency on external water resources, higher regional water footprints than the global average, increasing scarcity of renewable water resources, an increased number and capacity of dams exerting pressure on freshwater ecosystems, and a growing risk of conflicts between water users and countries. Access to water and sanitation remains a major challenge in the region. Territorial divisions separating coastal urban and remote rural areas are growing stronger, making isolated populations such as smallholder farmers particularly at risk of food and water insecurity. With climate change, precipitation is expected to decrease and temperatures to rise in the region, which will affect water supply (and thereby energy and food supply). It will also directly affect soil moisture and crop growth, thereby further increasing irrigation water needs. There are clear but difficult to measure interactions between the water, energy and agricultural sectors, as they are all interdependent, which calls for integrated policies and management. Agriculture being the largest water user in the region, further efforts need to be made to promote the use of non-conventional water resources. The conservation and restoration of Mediterranean agroecosystems is key to ensuring sustainable development. This requires better management of continuing arable land loss, land use intensification, and soil erosion and salinization. Integrated Water Resources Management and Water Demand Management (WDM) provide guidelines for achieving better water efficiency and reducing conflicts between users.

Seventy-one percent of the earth surfaces is covered by oceans. Water therefore is an important habitat for microorganisms and the other living beings. A consistent microbial biodiversity is present in water from phototrophs to chemioorganotrophs. The complex relationships between different microorganisms and the environment are often modified by organic, chemical and physic contaminations. The input of organic material can determine pathogenic pollution. The presence of pathogens has to be monitored to eliminate serious problems for animal and human health. Water, in fact, can be a vehicle direct (drinking water) or indirect (irrigation water) for microbial pathogens | Il 71% della superficie terrestre è costituito dagli oceani. L'acqua pertanto è un importante ambiente per i microrganismi, oltre che per tutti gli altri esseri viventi. Una grande varietà di tipi microbici colonizzano l'habitat acquatico, dai fototrofi ai chemiorganotrofi. Le dinamiche che si creano fra i diversi componenti microbici e l'ambiente sono spesso alterate da contaminazioni organiche, chimiche e fisiche. L'immissione di materiale organico può anche essere fonte di inquinamento di microrganismi patogeni la cui presenza va monitorata al fine di evitare seri problemi alla salute umana e animale. L'acqua, infatti, può rappresentare un veicolo di trasferimento, sia diretto (acqua potabile), sia indiretto (acque di irrigazione), di microrganismi patogeni

Cet article fait le point sur l'etat actuel des connaissances en matiere de consommations d'eau pour l'irrigation en France, tres variables dans le temps et l'espace. Au cours des dix dernieres annees, les superficies irriguees ont augmente de facon importante mais variable selon les regions, malgre la reforme de la PAC. Avec 43 % de la surface irriguee, le mais reste la principale culture irriguee. La connaissance des superficies irriguees, satisfaisante sur le plan statistique, est insuffisante pour une estimation quantitative des prelevements d'eau pour l'irrigation, du fait de la variabilite importante des besoins en eau des cultures et de la meconnaissance des pratiques d'apports d'eau des irriguants. Le Cemagref [Institut de recherche pour l'ingenierie de l'agriculture et de l'environnement] a developpe une methode d'estimation a l'echelle regionale des apports d'eau d'irrigation lors d'une secheresse severe. Les besoins en eau theoriques du mais, choisi comme culture de reference, sont evalues pour les principales regions de production, a partir des donnees climatiques et des caracteristiques des sols et en tenant compte des pratiques de restriction des apports d'eau des irriguants lors d'une secheresse prolongee. Sur la base de ce travail, il est possible de proposer un dispositif de suivi et d'analyse previsionnelle de la demande en eau des agriculteurs a l'echelle regionale, de facon a mieux apprecier les risques de tensions sur la ressource, et a mettre en place des modes de gestion plus efficaces. Ce dispositif devra s'appuyer entre autres sur une meilleure connaissance des pratiques des irriguants