Water resources.

water resources, uses over exploitation, floods droughts, dams benefits and problems

1. ShaikhSabina Meraj
Assistant Professor
Y. B. Chavancollege of Pharmcy
Water Resources

2. INDEX
Introduction
Water use and over-exploitation
Floods
Droughts
Traditional water management system
Big dams-benefits and problems

3. WATER RESOURCES
Waterisanindispensablenaturalresourceonthisearthonwhich
alllifedepends.
Althoughwaterisveryabundantonthisearth,yetitisvery
precious.
Outofthetotalwaterreservesoftheworld,about97%issalty
water,mostoftheanimalsandplantshave60-65%waterintheir
body.
Only3%isfreshwater.Eventhissmallfractionoffreshwateris
notavailabletousasmostofitislockedupinpolaricecapsand
just0.003%isreadilyavailabletousintheformofgroundwater
andsurfacewater

4. Waterischaracterizedbycertainuniquefeatureswhichmakeita
marvelousresource:
Itexistsasaliquidoverawiderangeoftemperaturei.e.from0°
to100°C.
Ithasthehighestspecificheat,duetowhichitwarmsupandcools
downveryslowlywithoutcausingshocksoftemperaturejerkstothe
aquaticlife.
IthasahighlatentheatofvaporizationHence,ittakesahuge
amountofenergyforgettingvaporized.That’swhyitproducesa
coolingeffectasitevaporates.

5. Itisanexcellentsolventforseveralnutrients.Thus,itcanserveasavery
goodcarrierofnutrients,includingoxygen,whichareessentialforlife.But,
itcanalsoeasilydissolvevariouspollutantsandbecomeacarrierof
pathogenicmicroorganisms.
Duetohighsurfacetensionandcohesionitcaneasilyrisethroughgreat
heightsthroughthetrunkeveninthetallestofthetreeslikeSequoia.
Ithasananomalousexpansionbehaviori.e.asitfreezes,itexpandsinsteadof
contractingandthusbecomeslighter.Itisbecauseofthispropertythateven
inextremecold,thelakesfreezeonlyonthesurface.Beinglightertheice
keepsfloating,whereasthebottomwatersremainatahighertemperature
andtherefore,cansustainaquaticorganismseveninextremecold.

6. WATER USE AND OVER-EXPLOITATION
Duetoitsuniquepropertieswaterisofmultipleusesforalllivingorganisms.
Waterisabsolutelyessentialforlife.
Mostofthelifeprocessestakeplaceinwatercontainedinthebody.
Uptakeofnutrients,theirdistributioninthebody,regulationoftemperature,
andremovalofwastesareallmediatedthroughwater.
Humanbeingsdependonwaterforalmosteverydevelopmentalactivity.
Waterisusedfordrinking,irrigation,transportation,washingandwastedisposal
forindustriesandusedasacoolantforthermalpowerplants.
Watershapestheearth’ssurfaceandregulatesourclimate.

7. Groundwater
About9.86%ofthetotalfreshwaterresourcesisintheformofgroundwateranditis
about35-50timesthatofsurfacewatersupplies.
Tillsometimebackgroundwaterwasconsideredtobeverypure.
However,oflate,evengroundwateraquifershavebeenfoundtobecontaminated.
Alayerofsedimentorrockthatishighlypermeableandcontainswateriscalledan
aquifer.
Aquifersmaybeoftwotypes:
Unconfinedaquiferswhichareoverlaidbypermeableearthmaterialsandtheyare
rechargedbywaterseepingdownfromaboveintheformofrainfallandsnowmelt.
Confinedaquiferswhicharesandwichedbetweentwoimpermeablelayersofrockor
sedimentsandarerechargedonlyinthoseareaswheretheaquiferintersectstheland
surface.Sometimestherechargedareaishundredsofkilometersawayfromthelocation
ofthewell

8. Effects of Groundwater Usage
Subsidence:Whengroundwaterwithdrawalismorethanitsrechargerate,the
sedimentsintheaquifergetcompacted,aphenomenonknownasgroundsubsidence.
Hugeeconomiclossesmayoccurduetothisphenomenonbecauseitresultsinthesinking
ofoverlyinglandsurface.Thecommonproblemsassociatedwithitincludestructural
damageinbuildings,fractureinpipes,reversingtheflowofsewersandcanalsandtidal
flooding.
Lowering of water table: Mining of groundwater is done extensively in arid and semi-
arid regions for irrigating crop fields. However, it is not advisable to do excessive mining
as it would cause a sharp decline in future agricultural production, due to lowering of
water table.
Water logging: When excessive irrigation is done with brackish water it raises the
water table gradually leading to water-logging and salinity problems.

9. FLOODS
Heavyrainfalloftencausesfloodsinthelow-lyingcoastal
areas.
Prolongeddownpourcanalsocausetheover-flowingoflakes
andriversresultingintofloods.
Deforestation,overgrazing,mining,rapidindustrialization,
globalwarmingetc.havealsocontributedlargelytoasharp
riseintheincidenceoffloods,whichotherwiseisanatural
disaster.

10. DROUGHTS
Whenannualrainfallisbelownormalandlessthanevaporation,drought
conditionsarecreated.
Ironically,thesedrought-hitareasareoftenhavingahighpopulationgrowth
whichleadstopoorlanduseandmakesthesituationworse.
Anthropogeniccauses:Droughtisameteorologicalphenomenon,but
duetoseveralanthropogeniccauseslikeovergrazing,deforestation,mining
etc.thereisspreadingofthedesertstendingtoconvertmoreareasto
droughtaffectedareas.
Erroneousandintensivecroppingpatternandincreasedexploitationof
scarcewaterresourcesthroughwellorcanalirrigationtogethigh
productivityhasconverteddrought-proneareasintodecertifiedones.

11. Remedial measures:
Indigenousknowledgeincontrolofdroughtanddesertification
canbeveryusefulfordealingwiththeproblem.
Carefullyselectedmixedcroppinghelpoptimizeproduction
andminimizetherisksofcropfailures.
SocialForestryandWastelanddevelopmentcanprovequite
effectivetofighttheproblem,butitshouldbebasedonproper
understandingofecologicalrequirementsandnaturalprocess.

12. TRADITIONAL WATER MANAGEMENT SYSTEM
InIndia,eventoday,thereareseveralvillageswherewatermanagement
isdonenotbytheIrrigationDepartment,butbylocalmanagers.
InsouthIndia,aneerkattimanagesthetraditionaltanksvery
efficientlybasedonhis/herknowledgeoftheterrain,drainageand
irrigationneeds.
Theyusuallygivepreferencetothetailendfieldsanddecidepercapita
allocationofwaterbasedonthestockofavailablewaterinthetankand
cropneeds.
InMaharashtra,thewatermangersarecalledhavaldarsorjaghyas
whomanageandresolveconflictsbyoverseeingthewaterchannelsfrom
maincanaltothedistributorcanals

13. InLadakh,thewatermanagerisknownaschurpunwho
hasgotcompletechargewithfullpowersoverallocationof
availablewater.
Themajorsourceofwaterismeltwaterfromglaciersand
snowsupplementarybywaterfromspringsandmarshes.
Thewaterisdistributedtodifferentfieldsthroughan
intricatenetworkofearthenchannels.

14. BIG DAMS-BENEFITS AND PROBLEMS
Benefits
Rivervalleyprojectswithbigdamshaveusuallybeenconsideredtoplay
akeyroleinthedevelopmentprocessduetotheirmultipleuses.
Indiahasthedistinctionofhavingthelargestnumberofriver-valley
projects.
Thesedamsareoftenregardedasasymbolofnationaldevelopment.
Thetribalslivingintheareapinbighopesontheseprojectsastheyaim
atprovidingemploymentandraisingthestandardandqualityoflife.
Thedamshavetremendouspotentialforeconomicup-liftmentand
growth.

15. They can help in checking floods and famines, generate
electricity and reduce water and power shortage,
provide irrigation water to lower areas, provide drinking
water in remote areas and promote navigation, fishery
etc

16. Environmental Problems
The environmental impacts of big-dams are also too many due to which very often the
big dams become a subject of controversy. The impacts can be at the upstream as well
as downstream levels.
(A) The downstream impacts include the following:
(i) Water logging and salinity due to over irrigation
(ii) Micro-climatic changes
(iii) Reduced water flow and silt deposition in river
(iv) Flash floods
(v) Salt water intrusion at river mouth
(vi) Loss of land fertility along the river since the sediments carrying
nutrients get deposited in the reservoir
(vii) Outbreak of vector-borne diseases like malaria

17. (B) The upstream problems include the following:
(i) Displacement of tribal people
(ii) Loss of forests, flora and fauna
(iii) Changes in fisheries and the spawning grounds
(iv) Siltation and sedimentation of reservoirs
(v) Loss of non-forest land
(vi) Stagnation and waterloggingnear reservoir
(vii) Breeding of vectors and spread of vector-borne diseases
(viii) Reservoir induced seismicity (RIS) causing earthquakes
(ix) Growth of aquatic weeds.
(x) Microclimatic changes.

18. Thank you