A Study Of Groundwater Depletion In Kathmandu Environmental Sciences Essay
Kathmandu vale is confronting scarceness of imbibing H2O even during the showery season.Ground H2O is recharged of course by rain, thaw of snow and to some extent from beginnings likes rivers and lakes.Water from such beginnings moves beneath the land and recharges the land H2O by which its degree is maintained.
Land H2O is stored in shoal and deep aquifer.The H2O degree upto 100m in deepness is by and large characterized as shoal aquifer which is easy to reload as H2O from surface easy penetrates there.The degree deeper than 100m isdeep aquifer which shops fossil water.According to hydrogeologists H2O from deep aquifer is termed as fossil H2O as it can non be recharged every bit easy as shallow aquifer H2O.
There is ahapazard extraction of H2O from both shallow and deep aquifer in Kathmandu vale at present.The extraction of land H2O in Kathmandu vale is higher than the recharging which is cut downing the degree of land H2O.
Groundwater is a valuable resource both in the United States and throughout the universe. Where surface H2O, such as lakes and rivers, are scarce or unaccessible, groundwater supplies many of the hydrologic demands of people everyplace. In the United States. It is the beginning of imbibing H2O for about half the entire population and about all of the rural population, and it provides over 50 billion gallons per twenty-four hours for agricultural demands. Groundwater depletion, a term frequently defined as long-run water-level diminutions caused by sustained groundwater pumping, is a cardinal issue associated with groundwater usage. Many countries of the United States are sing groundwater depletion.
Excessive pumping can overdraw the groundwater “ bank history ”
The H2O stored in the land can be compared to money kept in a bank history. If you withdraw money at a faster rate than you deposit new money you will finally get down holding account-supply jobs. Pumping H2O out of the land faster than it is replenished over the long-run causes similar jobs. Groundwater depletion is chiefly caused by overextraction. Some of the negative effects of groundwater depletion:
drying up of Wellss
decrease of H2O in watercourses and lakes
impairment of H2O quality
increased pumping costs
What are some effects of groundwater depletion?
Pumping groundwater at a faster rate than it can be recharged can hold some negative effects of the environment and the people who are stakeholders of H2O:
Lowering of the H2O tabular array
The most terrible effect of inordinate groundwater pumping is that theAA H2O tabular array, below which the land is saturated with H2O, can be lowered. For H2O to be withdrawn from the land, H2O must be pumped from a well that reaches below the H2O tabular array. If groundwater degrees decline excessively far, so the well proprietor might hold to intensify the well, bore a new well, or, at least, effort to take down the pump. Besides, as H2O degrees decline, the rate of H2O the well can give may worsen.
Increased costs for the user
As the deepness to H2O additions, the H2O must be lifted higher to make the land surface. If pumps are used to raise the H2O more energy is required to drive the pump. Using the well can go more expensive.
Decrease of H2O in watercourses and lakes
Groundwater pumping can change how H2O moves between an aquifer and a watercourse, lake, or wetland by either stoping groundwater flow that discharges into the surface-water organic structure under natural conditions, or by increasing the rate of H2O motion from the surface-water organic structure into an aquifer. A related consequence of groundwater pumping is the lowering of groundwater degrees below the deepness that streamside or wetland flora needs to last. The overall consequence is a loss of riparian flora and wildlife home ground.
The basic cause ofAA land subsidenceAA is a loss of support below land. In other words, sometimes when H2O is taken out of the dirt, the dirt collapses, compacts, and beads. This depends on a figure of factors, such as the type of dirt and stone below the surface. Land remission is most frequently caused by human activities, chiefly from the remotion of subsurface H2O.
Deterioration of H2O quality
One water-quality menace to fresh groundwater supplies is taint from seawater seawater invasion. All of the H2O in the land is non fresh H2O ; much of the really deep groundwater and H2O below oceans is saline. In fact, an estimated 3.1 million three-dimensional stat mis ( 12.9 three-dimensional kilometres ) of saline groundwater exists compared to about 2.6 million three-dimensional stat mis ( 10.5 million three-dimensional kilometres ) of fresh groundwater ( Gleick, P. H. , 1996: Water resources. In Encyclopedia of Climate and Weather, erectile dysfunction. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823 ) . Under natural conditions the boundary between the fresh water and seawater tends to be comparatively stable, but pumping can do seawater to migrate inland and upward, ensuing in seawater taint of the H2O supply.
There is a immense demand for surface H2O because of quickly increasing population. The one-year imbibing H2O supply is unequal to run into the turning demand. Similarly, the usage of H2O for agribusiness is increasing. Following tabular array shows the handiness of surface H2O in Kathmandu
Table 1: Surface H2O handiness and its usage in Nepal
Entire one-year renewable surface H2O ( km3/yr )
Per Capita renewable surface H2O ( ‘000m3/yr )
Entire one-year backdown ( km3/yr )
Per Capita backdown ( ‘000 m3/yr )
Sectoral backdown as % of entire H2O backdown
Beginning: State of the Environment, Nepal, 2001, MoPE, ICIMOD, SACEP, NORAD, UNEP, Page No. 122
Water Supply and Demand:
About 146 million litres of H2O are used each twenty-four hours in the Kathmandu Valley ; of which 81 % is consumed by the urban population, 14 % by industries ( including hotels ) and the staying 5 % is utilized in rural countries. Surface H2O including H2O from oilers, supplies about 62 % of the entire H2O used, while groundwater including dhungedhara, inar and shallow tubewells supply 38 % of the entire H2O used. Of the entire H2O consumed, NESC`s part is approximately 70 % . The current groundwater abstraction rate of 42.5 million litres per twenty-four hours is about double the critical abstraction rate of 15 million liters/day harmonizing to JICA ( 1990 ) ( Beginning: Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 38 ) .
Following tabular array shows the estimated H2O demand for domestic usage in the Kathmandu vale H2O
Table 2: Estimated Water Demand for Domestic usage in the Kathmandu Valley ( mld )
Population ( million )
Demand for Drinking Water ( ml/day )
a ) Theoretical demand
B ) Observed demand medium degree 1
degree Celsiuss ) Non-domestic demand, Industry, hotels and others4
1 =150 liquid crystal display in 1994 and 2001, and 165 liquid crystal display in 2006 and 2011
2 =Rural demand is estimated to be 45 liquid crystal display in 1994, 61lcd in 2001, 76 liquid crystal display in 2006 and 95 liquid crystal display in 2011
3 =Estimated to be100 liquid crystal display in 1994, 124lcd in 2001, 135 liquid crystal display in 2006 and 149 liquid crystal display in 2011
4 =Annual growing of 5 %
Beginning: Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 38
Even after the completion of the Melamchi Project the H2O supply state of affairs by 2011 will stay more or less similar to1981, i.e. running at an approximative 30 % shortage.
In add-on, H2O demand is expected to increase significantly from assorted commercial, industrial constitutions, hotels and eating houses and the demand from the urban population is besides expected to increase.
As the current H2O supply can non prolong the urban population ‘s increasing demand for H2O, this could be the most of import factor restricting growing in the Kathmandu Valley. The H2O shortage could hold a important, inauspicious consequence on public wellness and sanitation ( Beginning: Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 39 ) .
Following tabular arraies shows the shortage in H2O supply for Domestic usage in Urban Areas:
Table 3The shortage in H2O supply for Domestic usage in Urban Areas
Beginning: Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 39
GROUNDWATER ZONE OF KATHMANDU VALLEY:
Groundwater occurs in the crannies and pores of the deposits. Based on the hydrological formation of assorted features including river sedimentations and others, the Kathmandu Valley is divided into three groundwater zones or territories: a ) northern zone, B ) , cardinal zone and degree Celsius ) southern groundwater zones ( JICA 1990 ) .
Northern Groundwater Zone:
The northern groundwater zone covers Bansbari, Dhobi khola, Gokarna, Manohar, Bhaktapur and some chief H2O supply Wellss of NWSC are situated in this country. In this zone, the upper sedimentations are composed of unconsolidated extremely permeable stuffs, which are about 60 m thick and organize the chief aquifer in the vale. This outputs big sums of H2O ( up to 40 l/s in trials ) . These harsh deposits are, nevertheless, interbedded with all right impermeable deposit at many topographic points. This northern groundwater zone has a relatively good recharging capacity.
Cardinal Groundwater Zone:
The cardinal groundwater zone includes the nucleus metropolis country and most portion of Kathmandu and Lalitpur Municipalities. Impermeable stiff black clay, sometimes up to 200 m thick, is found here along with lignite sedimentations. Beneath this bed, there are unconsolidated harsh deposit sedimentations of low permeableness. Marsh methane gas is found throughout the groundwater stored in this country. Being of soluble methane gas indicates dead aquifer status. The recharging capacity is low due to stiff impermeable bed. Harmonizing to dating analysis, age of gas well H2O is about 28,000 old ages. The confined groundwater is likely non-chargeable stagnant or “ dodo ”
Southern Groundwater Zone:
The southern groundwater zone is located in the geological line between Kirtipur. Godavari and the southern hills. Thick impermeable clay formation and low permeable
Recharge of Groundwater:
Harmonizing to the sedimentary development, the country suitable for reloading aquifers is located chiefly in the northern portion of the Kathmandu Valley and along the rivers or paleochannels. In the southern portion recharge is restricted to the country around Chovar and the Bagmati Channel, and likely along gravel fans near the hillside. Detailed probes of the recharge and related informations are losing.
Though the one-year precipitation of Kathmandu vale is rather high, the land status in general is non effectual for reloading aquifers from precipitation. Wide spread silty lacustraine sedimentations control groundwater recharge in the vale, interbredded with the impermeable clay, which prevents easy entree of leaching rainwater to the aquifers. Most of the one-year precipitation falls during monsoon from June to September, but runs off rapidly as surface flow and is non sustained during the dry season. Streams of the Kathmandu Valley have some H2O from the shoal aquifer after the monsoon season. ( Beginning: Hydrogeological Conditionss and Potential Barrier Sediments in the Kathmandu Valley, Final Report, Prepared by, B.D. Kharel, N.R. Shrestha, M.S. Khadka, V.K. Singh, B. Piya, R. Bhandari, M.P. Shrestha, M.G. Jha & A ; D. Mustermann, February 1998, page 28 )
Mani Gopal Jha, Mohan Singh Khadka, Minesh Prasad Shresth, Sushila Regmi, John Bauld and Gerry Jacobson, 1997 ( AGSO+GWRDB ) , The Assessment of Groundwater pollution in the Kathmandu Valley, Nepal, page 5
HMGN, MOPE, Kathmandu, Nepal, 1999, Environmental planning and Management of the Kathmandu Valley, P 38
Mani Gopal Jha, Mohan Singh Khadka, Minesh Prasad Shrestha, Sushila Regmi, John Bauld and Gerry Jacobson, The Assessment of Groundwater Pollution in the Kathmandu Valley, Nepal Page 14
HMG & A ; IUCN May 1995, Regulating Growth: Kathmandu Valley, Page. 47, 48 & A ; 49
5 Ground Water and the Rural Homeowner, Pamphlet ” , U.S. Geolgoical Survey, by Waller, Roger M. , ,1982