Surface circulation in the Mediterranean Sea
The large-scale circulation of the Mediterranean Sea has been
described as sub-basin-scale and mesoscale gyres interconnected
and bounded by currents and jets with strong seasonal and inter-annual variability (Millot and Taupier-Letage 2005). This general circulation flow impinges on the coastal regions and strongly influences the local dynamics of currents. Shelf areas in the Mediterranean are comparatively small and are separated from the dee...
19 Nov 2013 - by GRID-Arendal
Groundwater contamination from canals - Hat Yai, Thailand
In areas where surface water is not readily available (located far away from areas where it is needed), groundwater is the primary water source. This graphic shows the chloride concentration and the potassium concentration, in milligrams per litre, in the city of Hat Yai's canals. It also shows the degree to which the polluted canal water has mixed with the groundwater. Finally, the graphic explains how the city's groundwater has been polluted by...
17 May 2005 - by Delphine Digout, UNEP/GRID-Arendal
Unsustainable water withdrawals for irrigation
The imbalance in long-term water budgets necessitates diversion of surface water or the tapping of groundwater resources. The areas shown with moderate-to-high levels of unsustainable use occur over each continent and are known to be areas of aquifer mining or major water transfer schemes.
30 Nov 2007 - by Philippe Rekacewicz, Emmanuelle Bournay, UNEP/GRID-Arendal
Many of the largest rivers in the Himalayas Hindu Kush region are strongly dependent upon snow and glacial melt for waterflow
Except for the fact that glaciers are melting rapidly in many places, we do not have adequate data to more accurately project when and where water scarcity will affect irrigation schemes in full. Making accurate projections is also difficult because of variations in the effects on ground and surface water, as well as on water for urban needs and industrial purposes Furthermore, the cost of water may also increase, seriously complicating the water...
02 Feb 2009 - by Ieva Rucevska, UNEP/GRID-Arendal
Freshwater alkalinity: 1976-2008
Alkalinity is commonly used to indicate a water body’s capacity to buffer against acidity; that is, the ability to resist, or dampen, changes in pH. Thus, alkaline compounds in water, such as bicarbonates, carbonates, and hydroxides, lower the acidity of the water and increase the pH.
Alkalinity (as CaCO3) was analysed for all sampling stations available at the continental level. Concentrations remained reasonably steady between the two decades ...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), February 2006
Renewable surface water produced internally
It is difficult to determine the amount of renewable water produced internally from the total renewable water resources (external and internal). However the FAO gives a rather precise definition of this indicator. Internal Renewable Water Resources (IRWR) includes:
- Average precipitation: long-term double average over space and time of the precipitation falling on the country in a year.
- Surface water produced internally: long-term average an...
26 Jan 2009 - by GRID-Arendal