water

in the near future WATER is a biggest matter to become ,
i mean the perfect good usable water ,most importantly we must want to drink , secondary for other necessary's . water is main most important thing for all the living creatures to live,
actually after the   O2 . lots of people of some country's like ,Somali/Ethiopia/ mainly have not good healthy usable water to drink. those country's like deserts  also no foods to people 
and some country's like Saudi Arabia/and some other middle east  country's dont have good healthy water in there country's . they buy water from other country's who have good water 
like we buy oil from middle east 

                                                         you think who is responsible for this , what was the reason to our good water resources getting lost , its all happen because of  human activities  we are the one' s who doing this damage to our society, some one can say this is happen 
because of matter  of climate change , but it also happen from human activity's .

how can human activity's effects for water resources  

1.how are aquatic ecosystem threatened by sediment in water 
2.how can different kind of pollution  effect water resources
3.what are the  consequences of  excessive water withdrawal 
4.how is climate change effecting water resources


1.how are aquatic ecosystem threatened by sediment in water 

 Sediments occur in water bodies both naturally and as a result of various human actions. When they occur excessively, they can dramatically change our water resources. Sediments occur in water mainly as a direct response to land-use changes and agricultural practices, although sediment loads can occur naturally in poorly vegetated terrains and most commonly in arid and semi-arid climates following high intensity rainfall.  summarizes the principal sources of excessive sediment loads and identifies the major impacts that this degree of sediment loading can have on aquatic systems and the services that water resources can provide. A recently documented and increasing source of high sediment loads is the construction of new roads in developing countries where little consideration is given to the impacts of such actions on aquatic systems and downstream water supplies. Globally, the effects of excessive sedimentation commonly extend beyond our freshwater systems and threaten coastal habitats, wetlands, fish and coral reefs in marine environments . The importance of sediment control should be an integral consideration in any water resources development and protection strategy. UNESCO’s International Sediment Initiative (ISI) project will attempt to improve the understanding of sediment phenomena, and provide better protection of the aquatic and terrestrial environments.

2. how can different kind of pollution  effect water resources

     Humans have long used air, land and water resources as ‘sinks’ into which we dispose of the wastes we generate. These disposal practices leave most wastes inadequately treated, thereby causing pollution. This in turn affects precipitation , surface waters  and groundwater , as well as degrading ecosystems. The sources of pollution that impact our water resources can develop at different scales (local, regional and global) but can generally be categorized according to nine types. Identification of source types and level of pollution is a prerequisite to assessing the risk of the pollution being created to both the aquatic systems and, through that system, to humans and the environment. With the knowledge of the principal sources of the pollution, the appropriate mitigation strategy can be identified to reduce the impact on the water resources.

3.what are the  consequences of  excessive water withdrawal 

    The problems of over-abstraction in surface water bodies and groundwater, sometimes tied directly to upstream diversions, reservoirs and deforestation, are well documented. The problems commonly become exacerbated when combined with extended natural dry periods. Notable examples of substantive reductions in large major river flows can be found around the world. Some of the basins suffering from this reduction are: Niger, Nile, Rwizi, Zayandeh-Rud (Africa); Amu Darya, Ganges, Jordan, Lijiang, Syr Darya, Tigris and Euphrates, Yangtze and Yellow (Asia); Murray-Darling (Australia); and Columbia, Colorado, Rio Grande and San Pedro (North America). Examples of lakes and inland sea areas decreasing dramatically in size and volume include: Lakes Balkhash, Drigh, Hamoun, Manchar, and the Aral and Dead Seas (Asia); Lakes Chad, Nakivale and in the Eastern Rift Valley Area, e.g. Nakuru (Africa); Lake Chapala (North America); and Mono Lake and the Salton Sea (North America). Dramatically lowered water levels in aquifers are increasingly reported, for example in the Mexico City and the Floridian and Ogallala aquifers (North America), as well as in China, India, Iran, Pakistan and Yemen (Asia).

4.how is climate change effecting water resources 

   Climate change increases water resources stresses … where runoff decreases, including around the Mediterranean, in parts of Europe, central and southern America, and southern Africa. In other water-stressed parts of the world – particularly in southern and eastern Asia – climate change increases runoff, but this may not be very beneficial in practice because increases tend to come during the wet season and extra water may not be available during the dry season.

         However, he further points out that model results differ by up to four times in terms of persons impacted according to different population and climate scenarios. 

Shiklamanov and Rodda (2003) conclude that only general predictions and observations have been developed based on the assessments of global warming impacts on water resources to date. They agree with Arnell (2004) that assessments of future water resources can only be obtained by using estimates of possible regional (rather than global) changes in climate (primarily precipitation and temperature by seasons and months). They specify that the existing climate change estimates are extremely unreliable even for the largest regions and river basins. Furthermore, they suggest that the gap in knowledge related to the specific impacts of global warming on water resources is one of the largest scientific challenges in hydrology today.