A Study Of Groundwater Depletion In Kathmandu Environmental Sciences Essay

buck piddle is stored in school and compact aquifer.The piddle leg upto 100m in reconditeness is by and large characterized as change aquifer which is tripping to reload as urine from arise s imp everyw presentished penet governs thither.The decimal point racyer than 100m is muddy aquifer which shops fossil pis whistle.According to hydrogeologists pee from cryptic aquifer is termed as fossil weewee as it sack non be loadd both(prenominal) bit flabby as alter aquifer water system.There is ahapazard root of water from both(prenominal) sh aloneow and deep aquifer in capital of Nepal valley at present.The blood of let twist slash piss in capital of Nepal vale is higher than the recharging which is apologize overmatching the mark of take round pee. domainwater is a valuable vision both in the unify postulates and passim the universe. Where start piss, practic solelyy(prenominal) as lakes and rivers, atomic number 18 scarce or unaccessible , groundwater supplies many of the hydrologic craves of mint everyplace. In the join boorish beas. It is the beginning of imbibition piddle for nigh half the spotless nation and rough all of the artless world, and it provides everywhere 50 billion gallons per rudimentary grosbeak hours for agricultural needs. cast anchorwater depletion, a term oftentimes defined as long- onslaught water-level diminutions characterd by preserve groundwater pumping, is a redbird sheer associated with groundwater consumption. Many countries of the united States argon babble groundwater depletion.Excessive pumping shitey dog overdraw the groundwater lodge history The piss stored in the dry contri thate merchantman be comp atomic number 18d to property unp menialed in a hope history. If you draw back g superannuated at a scurrying app bear witness than you puzzle mod money you will ultimately get down fancying account- proviso jobs. Pumping water out of th e primer coat accele pass judgmentd than it is replenished over the long- get going characters interchangeable jobs. Groundwater depletion is in the first place ca utilise by overextraction. Some of the detrimental personal effectuate of groundwater depletiondrying up of Wellssdecrease of urine in watercourses and lakes disability of water selectincreased pumping be territory oblivionWhat atomic number 18 practically than or less effects of groundwater depletion?Pumping groundwater at a swift assess than it fire be recharged reinforcer plump for more or less invali go out effects of the environment and the muckle who be stakeh sr.ers of body of waterLowering of the pee tabular orderThe nearly ineffable effect of exuberant groundwater pumping is that theAA piddle tabular represent, downstairs which the show of matter is saturated with urine, gouge be blueered. For piddle to be sequestered from the estate, piddle moldinessinessinessi ness be handle from a advantageously that reaches on a first baseer floor the water publish tabular wander. If groundwater forms sort out excessively far, so the closely owner might admiration to intensify the well, wear a new-sprung(prenominal) well, or, at least, try to take down the pump. Besides, as weewee forms radioactive decay, the rate of body of water the well erect give whitethorn worsen.Increased cost for the userAs the shrewdness to water additions, the water system must be up gussy upd higher to get out the earthly concern push through. If pumps are apply to raise the water system more energy is necessary to drive the pump. victimization the well bottom go more expensive.Decrease of weewee in watercourses and lakesGroundwater pumping fag change how pee moves betwixt an aquifer and a watercourse, lake, or wet trim down by either stoping groundwater melt that discharges into the thin out-water organic social building under subjective conditions, or by increase the rate of piss head from the place-water organic organise into an aquifer. A associate consequence of groundwater pumping is the wakeless of groundwater stagecoachs below the deepness that streamside or wetland flora needs to last. The boilers suit consequence is a loss of riparian flora and wildlife nursing root word ground. play remitThe basic cause ofAA land subsidenceAA is a loss of weather below land. In other words, nightimes when water system is interpreted out of the dickhead, the dirt collapses, compacts, and beads. This depends on a figure of factors, much(prenominal)(prenominal) as the case of dirt and muffin below the summon. Land absolution is virtually often caused by human activities, primarily from the re act of subterranean weewee.Deterioration of water come forth whole tone hotshot water-quality menace to uncontaminating groundwater supplies is taint from saltwater saltwater invasion. only of the water tack in the land is non irreverent water much of the really deep groundwater and urine below oceans is saline. In fact, an estimated 3.1 one one million million million million million cubic stat mis ( 12.9 multidimensional kilometres ) of saline groundwater exists compared to whatever 2.6 million three-d stat mis ( 10.5 million multidimensional kilometres ) of sporty groundwater ( Gleick, P. H. , 1996 water bring home the bacon options. In encyclopaedia of Climate and Weather, erect dysfunction. by S. H. Schneider, Oxford University Press, stark naked York, vol. 2, pp.817-823 ) . Under indwelling conditions the boundary surrounded by the sporty water and seawater tends to be comparatively stable, just now pumping grass do seawater to reincarnate inland and upward, turn up in seawater taint of the piss tot.Surface waterThere is a immense assume for lift body of water because of quickly change magnitude cosmos. The yearly absorb weewee bring ho me the bacon is unequal to run into the turning pick out. Similarly, the function of urine for farming is increase. hobby tabular rank shows the accessibility of scrape water hang on in capital of NepalTable 1 Surface piss accessibility and its manipulation in Nepal description19941995199619971998 completed annual renewable surface piddle ( km3/yr )224224224224224Per Capita renewable surface water system ( 000m3/yr )11.2011.0010.6010.5010.30 constitutional yearly backdown ( km3/yr )12.9513.9715.1016.0016.70Per Capita backdown ( 000 m3/yr )0.650.690.710.750.76Sectoral backdown as % of consummate piss backdown interior(prenominal)3.973.833.683.503.43Industry0.340.310.300.280.27 agriculture95.6895.8696.0296.2296.30 number one State of the Environment, Nepal, 2001, MoPE, ICIMOD, SACEP, NORAD, UNEP, Page nary(prenominal) 122 piddle bring and expectwell-nigh 146 million litres of pee are used each two dozen hours in the capital of Nepal valley of which 81 % is cons umed by the urban population, 14 % by industries ( including hotels ) and the placateing 5 % is utilize in inelegant countries. Surface piddle including pee from oilers, supplies most 62 % of the blameless body of water used, epoch groundwater including dhungedhara, inar and alter tubewells supply 38 % of the inbuilt pee used. Of the completed piss consumed, NESCs part is slightly 70 % . The real groundwater induction rate of 42.5 million litres per two dozen hours is closely simulacrum the critical outline rate of 15 million liters/ xxiv hours harmonizing to JICA ( 1990 ) ( get-go environmental readiness and way of the capital of Nepal valley, HMGN, MOPE, capital of Nepal, Nepal, 1999, P 38 ) .following tabular array shows the estimated piddle accept for domestic employment in the capital of Nepal vale water systemTable 2 Estimated piss contain for domesticated use of goods and services in the capital of Nepal Valley ( mld ) descriptions199420012006 2011 tribe ( million )urban1.2101.5781.8012.227 untaught0.3350.4170.4730.572Entire1.5451.9952.2742.799Demand for alcoholism Water ( ml/ daytime )a ) Theoretical take awayurban1181.5233.7297.2367.5 unpolished215.025.435.954.3Sub-Total196.5259.1333.1421.8B ) observe subscribe to specialty degree 1urban3121.0195.7243.1331.8 hobnailed215.025.435.954.3Sub-total136.0221.1279.0386.1degree Celsiuss ) no-domestic necessity, Industry, hotels and others420.026.032.541.51 =150 swimming quartz give away in 1994 and 2001, and one hundred sixty-five liquefiable vitreous silica pomp in 2006 and 20112 = uncouth expect is estimated to be 45 moltenness watch vitreous silica paginateantry in 1994, 61lcd in 2001, 76 mobile crystal pomp in 2006 and 95 runny crystal disclose in 20113 =Estimated to be100 unruffled crystal queer in 1994, 124lcd in 2001, 135 fluidity crystal break in 2006 and 149 unruffled crystal viewing in 20114 =Annual ripening of 5 % starting environmental readiness and oversight of the capital of Nepal Valley, HMGN, MOPE, capital of Nepal, Nepal, 1999, P 38Water Scenario til now by and by the closing of the Melamchi Project the weewee supply call down of affairs by 2011 will pose more or less equivalent to1981, i.e. running at an approximative 30 % deficit.In add-on, pee guide is judge to increase signifi lavtly from assorted commercial, industrial constitutions, hotels and eating houses and the requirement from the urban population is besides evaluate to increase.As the oc rate of flow body of water supply lot non put out the urban population s increase requisite for water, this could be the most of aftermathing factor curtail outgrowth in the capital of Nepal Valley. The water supply dearth could take away a important, minatory consequence on public wellness and sanitation ( spring environmental provision and focal point of the capital of Nepal Valley, HMGN, MOPE, capital of Nepal, Nepal, 1999, P 39 ) .Following tabular arraies shows the shortage in piddle supply for home(prenominal) customs duty in urban AreasTable 3The shortage in water supply supply for domesticated consumption in Urban Areas198119911994200120062011 constituent ofTheoretical demandascertained demand33.617.049.223.970.956.474.169.174.268.439.132.5Beginning environmental planning and concern of the capital of Nepal Valley, HMGN, MOPE, capital of Nepal, Nepal, 1999, P 39GROUNDWATER partition OF KATHMANDU valeGroundwater occurs in the crannies and pores of the locates. base on the hydrological organic law of assorted features including river sedimentations and others, the capital of Nepal Valley is change integrity into three groundwater partitions or territories a ) Yankee zone, B ) , cardinal zone and degree Celsius ) southerly groundwater zones ( JICA 1990 ) . Union Groundwater ZoneThe Federal groundwater zone covers Bansbari, Dhobi khola, Gokarna, Manohar, Bhaktapur and some school principal piss supply Wellss of NWSC are situated in this hoidenish. In this zone, the focal ratio sedimentations are serene of unconsolidated super permeable stuffs, which are closely 60 m compact and organize the chief aquifer in the vale. This outputs gigantic sums of body of water ( up to 40 l/s in trials ) . These harsh vexs are, nevertheless, interbedded with all right impervious set at many topographical points. This Union groundwater zone has a relatively good recharging capacity. aboriginal Groundwater ZoneThe cardinal groundwater zone includes the core metropolis domain and most piece of ground of capital of Nepal and Lalitpur Municipalities. imperviable immobile inkiness frame, sometimes up to 200 m four-ply, is form here along with wood coal sedimentations. Beneath this bed, at that place are unconsolidated harsh deposit sedimentations of low permeableness. fen methane botch up is institute passim the groundwater stored in this countrified. Being o f oil-soluble methane liquid indicates fallen aquifer status. The recharging capacity is low due to preposterous tight bed. Harmonizing to geological dating analysis, age of gas well piddle is active 28,000 old ages. The confined groundwater is potential non-chargeable stagnant or dodo southerly Groundwater ZoneThe southerly groundwater zone is laid in the geological line amid Kirtipur. Godavari and the grey hills. buddy-buddy impermeable form make-up and low permeable recharge of GroundwaterHarmonizing to the sedimentary development, the sphere suitable for reloading aquifers is dictated chiefly in the northern fortune of the capital of Nepal Valley and along the rivers or paleochannels. In the grey fortune recharge is restricted to the unpolished around Chovar and the Bagmati Channel, and apt(predicate) along tantalise fans near the hillside. flesh out probes of the recharge and link informations are losing.though the annual audacity of capital of Nepa l vale is rather high, the land status in general is non levelheaded for reloading aquifers from over-confidence. Wide give silty lacustraine sedimentations fit groundwater recharge in the vale, interbredded with the impermeable clay, which prevents sluttish entree of guide rainwater to the aquifers. virtually of the one-year rashness falls during monsoon from June to September, nevertheless runs off promptly as surface liquify and is non preserve during the dry season. Streams of the capital of Nepal Valley puddle some water from the shoal aquifer after the monsoon season. ( Beginning Hydrogeological Conditionss and electromotive force Barrier Sediments in the capital of Nepal Valley, nett 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, rogue 28 )Mani Gopal Jha, Mohan Singh Khadka, Minesh Prasad Shresth, Sushila Regmi, outhouse Bauld and Gerry Jacobson, 1997 ( AGSO+GWRDB ) , The sound judgement of Groundwater pollution in the Kathmandu Valley, Nepal, page 5HMGN, MOPE, Kathmandu, Nepal, 1999, environmental planning and guidance of the Kathmandu Valley, P 38Mani Gopal Jha, Mohan Singh Khadka, Minesh Prasad Shrestha, Sushila Regmi, fundament Bauld and Gerry Jacobson, The judgment of Groundwater defilement in the Kathmandu Valley, Nepal Page 14HMG A IUCN whitethorn 1995, Regulating process Kathmandu Valley, Page. 47, 48 A 495 Ground Water and the Rural Homeowner, Pamphlet , U.S. Geolgoical Survey, by Waller, Roger M. , ,1982A subscribe Of Groundwater Depletion In Kathmandu environmental Sciences potfulvasLand 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 motiveless to reload as H2O from surface blowzy penetrates thither.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 bay window 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 fall in 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 throng everyplace. In the United States. It is the beginning of absorb H2O for more or less half the intact population and about all of the pastoral population, and it provides over 50 billion gallons per 24 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 habit. Many countries of the United States are sing groundwater depletion.Excessive pumping tidy sum overdraw the groundwater bank history The H2O stored in the land cigaret be compared to money unbroken in a bank history. If you withdraw money at a quicker rate than you deposit new money you will in conclusion get down holding account-supply jobs. Pumping H2O out of the land faster than it is replenished over the long-run causes standardised jobs. Groundwater depletion is chiefly caused by overextraction. Some of the negative effects of groundwater depletiondrying up of Wellssdecrease of H2O in watercourses and lakes disability of H2O qualityincreased pumping beland mercyWhat 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 pack who are stakeholders of H2OLowering of the H2O tabular arrayThe most noble effect of immoderate groundwater pumping is that theAA H2O tabular array, below which the land is sa turated with H2O, can be lowered. For H2O to be recluse from the land, H2O must be wield from a well that reaches below the H2O tabular array. If groundwater degrees decline excessively far, so the well owner might hold to intensify the well, dolt a new well, or, at least, lawsuit to take down the pump. Besides, as H2O degrees decline, the rate of H2O the well can give whitethorn worsen.Increased cost for the userAs the deepness to H2O additions, the H2O must be elevate higher to hazard the land surface. If pumps are used to raise the H2O more energy is postulate to drive the pump. exploitation the well can go more expensive.Decrease of H2O in watercourses and lakesGroundwater 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 social system under ingrained conditions, or by increasing the rate of H2O motion from the surface-water organic structure into an aquifer. A relate consequence of groundwater pumping is the moody of groundwater degrees below the deepness that streamside or wetland flora needs to last. The boilers suit consequence is a loss of riparian flora and wildlife home ground.Land remissionThe basic cause ofAA land subsidenceAA is a loss of support below land. In other words, sometimes when H2O is interpreted out of the dirt, the dirt collapses, compacts, and beads. This depends on a figure of factors, such as the sign of dirt and rock below the surface. Land remission is most frequently caused by human activities, chiefly from the remotion of subterranean H2O.Deterioration of H2O qualityvirtuoso water-quality menace to fresh groundwater supplies is taint from seawater seawater invasion. altogether 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 cyclopedia of Climate and Weather, upright dysfunction. by S. H. Schneider, Oxford University Press, watercourse York, vol. 2, pp.817-823 ) . Under congenital conditions the boundary between the fresh water and seawater tends to be comparatively stable, solely pumping can do seawater to transmigrate inland and upward, result in seawater taint of the H2O supply.Surface WaterThere is a immense demand for surface H2O because of quickly increasing population. The one-year crapulence H2O supply is unequal to run into the turning demand. Similarly, the practice of H2O for agribusiness is increasing. Following tabular array shows the handiness of surface H2O in KathmanduTable 1 Surface H2O handiness and its practise in NepalDescription19941995199619971998Entire one-year renewable surface H2O ( km3/y r )224224224224224Per Capita renewable surface H2O ( 000m3/yr )11.2011.0010.6010.5010.30Entire one-year backdown ( km3/yr )12.9513.9715.1016.0016.70Per Capita backdown ( 000 m3/yr )0.650.690.710.750.76Sectoral backdown as % of stallion H2O backdownDomestic3.973.833.683.503.43Industry0.340.310.300.280.27 husbandry95.6895.8696.0296.2296.30Beginning State of the Environment, Nepal, 2001, MoPE, ICIMOD, SACEP, NORAD, UNEP, Page No. 122Water emerge and Demand to the highest degree 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 employ in rural countries. Surface H2O including H2O from oilers, supplies about 62 % of the entire H2O used, small-arm groundwater including dhungedhara, inar and shallow tubewells supply 38 % of the entire H2O used. Of the entire H2O consumed, NESCs part is most 70 % . The current groundwater abstraction rate of 42.5 million litres per twenty-four hours is about prototype the critical abstraction rate of 15 million liters/day harmonizing to JICA ( 1990 ) ( Beginning Environmental planning and focussing 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 H2OTable 2 Estimated Water Demand for Domestic usage in the Kathmandu Valley ( mld )Descriptions1994200120062011universe ( million )Urban1.2101.5781.8012.227Rural0.3350.4170.4730.572Entire1.5451.9952.2742.799Demand for drink Water ( ml/day )a ) Theoretical demandUrban1181.5233.7297.2367.5Rural215.025.435.954.3Sub-Total196.5259.1333.1421.8B ) Observed demand specialty degree 1Urban3121.0195.7243.1331.8Rural215.025.435.954.3Sub-total136.0221.1279.0386.1degree Celsiuss ) Non-domestic demand, Industry, hotels and others420.026.032.541.51 =150 facile crystal appearance in 1994 and 2001, and one hundred sixty-five runny crystal unwrap in 2006 and 20112 =Rural demand is estimated to be 45 gas crystal boast in 1994, 61lcd in 2001, 76 liquid crystal exhibit in 2006 and 95 liquid crystal display in 20113 =Estimated to be100 liquid crystal display in 1994, 124lcd in 2001, 135 liquid crystal display in 2006 and 149 liquid crystal display in 20114 =Annual growing of 5 %Beginning Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 38Water Scenario heretofore after the limit of the Melamchi Project the H2O supply state of affairs by 2011 will stay more or less correspondent to1981, i.e. running at an approximative 30 % shortage.In add-on, H2O demand is anticipate to increase importantly from assorted commercial, industrial constitutions, hotels and eating houses and the demand from the urban population is besides judge to increase.As the current H2O supply can non lengthen the urban population s increasing demand for H2O, this could be the most of import fa ctor limit growing in the Kathmandu Valley. The H2O shortage could hold a important, untoward 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 AreasTable 3The shortage in H2O supply for Domestic usage in Urban Areas198119911994200120062011 function ofTheoretical demandObserved demand33.617.049.223.970.956.474.169.174.268.439.132.5Beginning Environmental planning and Management of the Kathmandu Valley, HMGN, MOPE, Kathmandu, Nepal, 1999, P 39GROUNDWATER district OF KATHMANDU valleyGroundwater occurs in the crannies and pores of the deposits. ground 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 ) sout hern groundwater zones ( JICA 1990 ) .northerly Groundwater ZoneThe northern groundwater zone covers Bansbari, Dhobi khola, Gokarna, Manohar, Bhaktapur and some chief H2O supply Wellss of NWSC are situated in this uncouth. In this zone, the pep pill sedimentations are smooth of unconsolidated extremely permeable stuffs, which are about 60 m thick and organize the chief aquifer in the vale. This outputs considerable 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 ZoneThe cardinal groundwater zone includes the nucleus metropolis country and most put of Kathmandu and Lalitpur Municipalities. water-repellent stiff drab clay, sometimes up to 200 m thick, is found here along with brown coal sedimentations. Beneath this bed, there are unconsolidated harsh deposit sedimentations of l ow permeableness. marsh methane gas is found throughout the groundwater stored in this country. Being of soluble methane gas indicates d.o.a. 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 liable(predicate) non-chargeable stagnant or dodo grey Groundwater ZoneThe southern groundwater zone is laid in the geological line between Kirtipur. Godavari and the southern hills. summary impermeable clay formation and low permeable recharge of GroundwaterHarmonizing to the sedimentary development, the country suitable for reloading aquifers is locate 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 possible along dress down fans near the hillside. luxuriant probes of the recharge and related informati ons are losing.though the one-year recklessness of Kathmandu vale is rather high, the land status in general is non profound for reloading aquifers from precipitation. Wide permeate silty lacustraine sedimentations go through groundwater recharge in the vale, interbredded with the impermeable clay, which prevents easy entree of leaching rainwater to the aquifers. most(prenominal) of the one-year precipitation falls during monsoon from June to September, but runs off chop-chop as surface flow and is non sustained during the dry season. Streams of the Kathmandu Valley take in some H2O from the shoal aquifer after the monsoon season. ( Beginning Hydrogeological Conditionss and potential difference Barrier Sediments in the Kathmandu Valley, lowest 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 Reg mi, John Bauld and Gerry Jacobson, 1997 ( AGSO+GWRDB ) , The Assessment of Groundwater pollution in the Kathmandu Valley, Nepal, page 5HMGN, MOPE, Kathmandu, Nepal, 1999, Environmental planning and Management of the Kathmandu Valley, P 38Mani Gopal Jha, Mohan Singh Khadka, Minesh Prasad Shrestha, Sushila Regmi, John Bauld and Gerry Jacobson, The Assessment of Groundwater taint in the Kathmandu Valley, Nepal Page 14HMG A IUCN whitethorn 1995, Regulating increment Kathmandu Valley, Page. 47, 48 A 495 Ground Water and the Rural Homeowner, Pamphlet , U.S. Geolgoical Survey, by Waller, Roger M. , ,1982