Mediterranean water resources in a global change scenario

Abstract

Mediterranean areas of both southern Europe and North Africa are subject to dramatic changes that will affect the sustainability, quantity, quality, and management of water resources. Most climate models forecast an increase in temperature and a decrease in precipitation at the end of the 21st century. This will enhance stress on natural forests and shrubs, and will result in more water consumption, evapotranspiration, and probably interception, which will affect the surface water balance and the partitioning of precipitation between evapotranspiration, runoff, and groundwater flow. As a consequence, soil water content will decline, saturation conditions will be increasingly rare and restricted to periods in winter and spring, and snow accumulation and melting will change, especially in the mid-mountain areas. Future land management will be characterized by forest and shrub expansion in most Mediterranean mountain areas, as a consequence of farmland and grazing abandonment, with increasing human pressure localized only in some places (ski resorts, urbanized of valley floors). In the lowlands, particularly in the coastal fringe, increasing water demand will occur as a consequence of expansion of irrigated lands, as well as the growth of urban and industrial areas, and tourist resorts. Future scenarios for water resources in the Mediterranean region suggest (i) a progressive decline in the average streamflow (already observed in many rivers since the 1980s), including a decline in the frequency and magnitude of the most frequent floods due to the expansion of forests; (ii) changes in important river regime characteristics, including an earlier decline in high flows from snowmelt in spring, an intensification of low flows in summer, and more irregular discharges in winter; (iii) changes in reservoir inputs and management, including lower available discharges from dams to meet the water demand from irrigated and urban areas. Most reservoirs in mountain areas will be subject to increasing water resource uncertainty, because of the reduced influence of snow accumulation and snowmelt processes. Besides, reservoir capacity is naturally reduced due to increasing sedimentation and, in some cases, is also decreased to improve the safety control of 2 floods, leading to a reduction in efficiency for agriculture. And (iv) hydrological and population changes in coastal areas, particularly in the delta zones, affected by water depletion, groundwater reduction and saline water intrusion. These scenarios enhance the necessity of improving water management, water prizing and water recycling policies, in order to ensure water supply and to reduce tensions among regions and countries. Key words: climate change, meteorological and hydrological drought, land use changes, land cover changes, snow accumulation, snowmelt, river regime, stream flow decline, reservoir management, Mediterranean region common dependence on water availability to meet the needs of increasing populations and living standards, development of irrigated agriculture...

Direct Discharges of Domestic Wastewater are a Major Source of Phosphorus and Nitrogen to the Mediterranean Sea

“…With growing populations and increasingly arid conditions in the future, water reuse is bound to become more important in North Africa and the Middle East. 15,18,51 Additional incentives are (i) the cost, which is approximately half that of creating usable water by desalination plants, 51 and (ii) the recovery of P and N, under the form of biosolids, sludge and wastewater itself, which can be used as fertilizer for agricultural production. The latter also represents a mitigation measure to deal with the projected depletion of P mining reserves within the next 50−400 years.…”

Runoff and sediment yield from a small watershed in southeastern Spain (Lanjarón): implications for water quality

“…Various authors have reported that land-cover expansion or contraction at the watershed scale affects water resources by increasing or decreasing evapotranspiration and, hence, altering streamflow production (Boch and Hewlett 1982, Matheussen et al 2000, Delgado et al 2010, García et al 2011. In this context, seasonal variation of evapotranspiration has been observed with land-cover change (Dunn and Mackay 1995, Olchev et al 2008, Nosetto et al 2011, although the effects on runoff would occur only during summertime, when plants increase their water 274 284 294 304 314 324 334 344 354 364 9 19 29 39 49 59 69 79 89 99 109 119 129 139 149 159 169 179 189 199 209 219 229 239 249 259 275 285 295 305 315 325 335 345 355 365 9 19 29 39 49 59 69 79 89 99 109 119 129 139 149 159 169 179 189 199 209 219 229 239 249 259 demand, particularly in transitions between tree-and herbaceous-dominated covers.…”

“…The studies of rainfall, discharge, sediment transport and runoff-and sediment-contributing areas, are extremely important in interpreting the spatial and temporal dynamics in terms of quantity and quality of water resources (Lindim et al 2011). In this context, water resources are yielded primarily by headwaters situated in mountainous zones that are continuously perturbed by major changes in land use, which have a farreaching impact on reservoir management (López et al 2004, García et al 2011. For most European Mediterranean watersheds, the relationships among precipitation, discharge and suspended sediment during flood events are complex, hindering the formulation of predictive hydrological and sedimentological models.…”

Participatory analysis for adaptation to climate change in Mediterranean agricultural systems: possible choices in process design

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