WATER RESOURCES What is water?

A simple question that could extract various definitions from every single one of you present here. Oxford dictionary defines water as a colourless, transparent, odourless, liquid which is a inorganic compound of hydrogen and water f you as! me, "his definition tells us nothing a#out the magnitude of the importance of this single compound in our daily lives. would define water as simply An elixir of life $ood morning to one and all present here, %m &ranav and this is my friend 'umanth here to spea! to all of you a#out water resources. We all have heard of the familiar line water water everywhere #ut not a drop to drin! f you all could !indly loo! at the &ic.( on the chart, you would realise that truer words have never #een spo!en. "rue that )*+ of the ,arth%s surface is covered #y water #ut how much of that is availa#le to us? (-+? *+? (+? no. /ess than -.-(+ is availa#le for our daily consumption as fresh water. 'o it goes without saying that this precious resource must #e managed effectively for the sustainance of life form in our planet. Sources of Water

Surface water:'urface water is water in a river, la!e or fresh water wetland. 'urface water is naturally replenished #y precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and su#0surface seepage. 1ra2il is the country estimated to have the largest supply of fresh water in the world, followed #y 3ussiaand 4anada. Under River flow:"hroughout the course of a river, the total volume of water transported downstream will often #e a com#ination of the visi#le free water flow together with a su#stantial contri#ution flowing through su#0surface roc!s and gravels.5or many rivers in large valleys, this unseen component of flow may greatly exceed the visi#le flow. "his is nothing #ut the 'hallow ground water level and is !nown as the hydrophoric 2one. 6pic.78 Ground Water:'u#0surface water, or groundwater, is fresh water located in the pore space of soil and roc!s. "he natural input to su#0surface water is seepage from surface water. "he natural outputs from su#0surface water are springs and seepage to the oceans. Desalination:9esalination is an artificial process #y which saline water 6generally sea water8 is converted to fresh water. "he most common desalination processes are distillation and reverse osmosis. 9esalination is currently expensive compared to most alternative sources of water, and only a very small fraction of total human use is satisfied #y desalination. t is only economically practical for high0valued uses 6such as household and industrial uses8 in arid areas. "he most extensive use is in the &ersian $ulf. Frozen water:'everal schemes have #een proposed to ma!e use of ice#ergs as a water source, however to date this has only #een done for novelty purposes. "en of Asia:s largest rivers flow from there, and more than a #illion people:s livelihoods depend on them.

Uses of Water A ricultural: t is estimated that ;<+ of worldwide water use is for irrigation, with (*0=*+ of irrigation withdrawals #eing unsustaina#le.>;? t ta!es around 7,--- 0 =,--- litres of water to produce enough food to satisfy one person%s daily dietary need.>)? "his is a considera#le amount, when compared to that required for drin!ing, which is #etween two and five litres. "o produce food for the now over ) #illion people who inha#it the planet today requires the water that would fill a canal ten metres deep, (-- metres wide and 7(-- !ilometres long. !ndustrial: t is estimated that 77+ of worldwide water is used in industry.>;? @aAor industrial users include hydroelectric dams, thermoelectric power plants, which use water for cooling, ore and oil refineries, which use water in chemical processes, and manufacturing plants, which use water as a solvent. Water withdrawal can #e very high for certain industries, #ut consumption is generally much lower than that of agriculture. "ouse#old: t is estimated that B+ of worldwide water use is for household purposes.>;? "hese include drin!ing

water, #athing, coo!ing, sanitation, and gardening. 1asic household water requirements have #een estimated to #e around *- liters per person per day, excluding water for gardens. 9rin!ing water is water that is of sufficiently high quality so that it can #e consumed or used without ris! of immediate or long term harm. 'uch water is commonly called pota#le water. n most developed countries, the water supplied to households, commerce and industry is all of drin!ing water standard even though only a very small proportion is actually consumed or used in food preparation.

Recreational:3ecreational water use is usually a very small #ut growing percentage of total water use. 3ecreational water use is mostly tied to reservoirs. f a reservoir is !ept fuller than it would otherwise #e for recreation, then the water retained could #e categori2ed as recreational usage. 3elease of water from a few reservoirs is also timed to enhance whitewater #oating, which also could #e considered a recreational usage. Other examples are anglers, water s!iers, nature enthusiasts and swimmers. 3ecreational usage is usually non0consumptive. $olf courses are often targeted as using excessive amounts of water, especially in drier regions. Water Stress. "he concept of water stress is relatively simple. it applies to situations where there is not enough water for all uses, whether agricultural, industrial or domestic. it has #een proposed that when annual per capita renewa#le freshwater availa#ility is less than (,)-- cu#ic meters, countries #egin to experience periodic or regular water stress. 1elow (,--cu#ic meters, water scarcity #egins to hamper economic development and human health and well0#eing.

$o%ulation rowt#:n 7---, the world population was ;.7 #illion. "he CD estimates that #y 7-*- there will #e an additional =.* #illion people with most of the growth indeveloping countries that already suffer water stress.>(*? "hus, water demand will increase unless there are corresponding increases in water conservation and recycling of this vital resource.>(;? n #uilding on the data presented here #y the CD, the World 1an! goes on to explain that access to water for producing food will #e one of the main challenges in the decades to come. Access to water will need to #e #alanced with the importance of managing water itself in a sustaina#le way while ta!ing into account the impact of climate change, and other environmental and social varia#les.>()? E&%ansion of 'usiness Activit(:1usiness activity ranging from industriali2ation to services such as tourism and entertainment continues to expand rapidly. "his expansion requires increased water services including #oth supplyand sanitation, which can lead to more pressure on water resources and natural ecosystem Ra%id Ur)anisation:"he trend towards ur#ani2ation is accelerating. 'mall private wells and septic tan!s that wor! well in low0density communities are not feasi#le within high0density ur#an areas. Cr#ani2ation requires significant investment in water infrastructure in order to deliver water to individuals and to process the concentrations of wastewater E #oth from individuals and from #usiness. "hese polluted and contaminated waters must #e treated or they pose unaccepta#le pu#lic health ris!s. $ollution and water $rotection:Water pollution is one of the main concerns of the world today. "he governments of numerous countries have striven to find solutions to reduce this pro#lem. @any pollutants threaten water supplies, #ut the most widespread, especially in developing countries, is the discharge of raw sewage into natural watersF this method of sewage disposal is the most common method in underdeveloped countries, #ut also is prevalent in quasi0 developed countries such as 4hina, ndia, Depal and ran. 'ewage, sludge, gar#age, and even toxic pollutants are all dumped into the water. ,ven if sewage is treated, pro#lems still arise. "reated sewage forms sludge, which may #e placed in landfills, spread out on land, incinerated or dumped at sea.>7(? n addition to sewage, nonpoint source pollution such as agricultural runoff is a significant source of pollution in some parts of the world, along with ur#an stormwater runoff and chemical wastes dumped #y industries and governments.