The Kathmandu Valley, bowl shaped of 651 Km2 basin countries, has gently inclining vale floor, vale field patios with bit faces together with the inundation fields. The vale has warm temperate-semitropical clime and intended handbill shaped drainage basin with merely one mercantile establishment. The vale is filled with the fluvio-lacustrine deposits of quaternate age, doing three groundwater zones. Merely one H2O supply operator, Kathmandu Upatyaka Khanepani Limited ( KUKL ) , is functioning H2O supply in 5 Municipalities and 48 VDCs out of 99 VDCs utilizing 35 surface beginnings, 57 deep tubing Wellss, 20 WTPs, 43 service reservoirs and runing about 1300 major valves.
The part of groundwater part in entire production is an norm of 35 % in dry season and 11 % in moisture season with annual norm of 19 % in 2011, and found diminishing to 7 % , 4 % , and 3 % in 2016, 2019 and 2025 severally. Water supply is found to be improved with increasing ingestion rate from 41 lpcd in 2011 to 126 lpcd in 2025.If supply system is managed with project demand of 135 lpcd, the mean supply continuance will increase from 7 hours a twenty-four hours in 2011 to 23 hr a twenty-four hours in 2025.
Foremost grounds of providing much less comparison to calculated are perchance due to inaccurate prediction of served populations, absence of effectual MIS on H2O substructure systems, and inaccurate appraisal of unaccounted for H2O from system. Outside valley urban centres development, optimal land usage planning for possible recharge, presenting micro to macro degree rainwater reaping plans and riverhead forest protection are of import alternate options to minimise the spread between demand and supply of the vale.
Keywords: Kathmandu vale, KUKL, surface H2O, groundwater, HSG, Recharge, WTP, Water demand direction
The Kathmandu Valley is dwelling of Kathmandu metropolitan metropolis, capital of Nepal. Kathmandu, an ancient metropolis with a varied history, consists of Kathmandu, Bhaktapur and Lalitpur territories with five municipalities and 99 Village Development Committees. The significance of its historical development is the rise of urban sprawl in the vale, the design of Pagoda manner architecture and high lifting temples with stepped plinth cellar. After release in 1952, the new stage of development began with singular alteration in societal position, migration of people to the vale. The general tendencies of the urbanisation remained slow boulder clay the mid 1960ss. Merely in 1970ss, substructures like route webs, H2O supply systems started to develop quickly in the metropolis. As a consequence, the vale is turning quickly and randomly. This is the right clip to look earnestly at the turning urban jobs and available H2O resource in the vale. It is necessary to systematise the colony, implement the town planning more scientifically and transport out the land usage in proper mode so that available H2O resource potency could be maintained sustainably. There are assorted development programs for the vale, viz. building of outer pealing route, fast path route, railroads, urban colony development and building of nexus roads on the bank of the rivers. The deficits of surface and groundwater handiness and inundation harm are identified jobs in the vale. The vale basin is an ecologically of import basin.
The Kathmandu Valley is an intramontane basin, situated in the Lesser Himalayan zone. The lofty Higher Himalayan Range is merely approximately 65 kilometers aerial distance North of the Kathmandu. The vale is alone in its form and is surrounded by the goads of Lesser Himalayas. The vale basin is 30 kilometer long in the east-west and about 25 kilometers long in north-south way. Phulchoki Hill which is 2762m above the average sea degree ( msl ) in the sou’-east is the highest lift point in the country. Shivpuri Hill is about 2700m above msl in the North, Nagarkot is 2166m above msl in the E and Chandragiri is about 2561m above the msl in the West. The lowest lift point located by the side of Bagmati River is 1214 m above msl. About 55 % of the country is occupied by the vale floor, 35 % of foothill and the staying 10 % are cragged countries. In the vale, the wood ( cragged ) country is about 30 % of the entire country holding incline scope from 20 to 30 % , and staying country ( 70 % ) is holding mean incline of 0 to 4 % as shown in Fig.1.
Fig.1. Slope Map of Kathmandu valleyFig. 1 Slope Map of Kathmandu Valley ( Source: Shrestha, 2001 )
Kathmandu Valley is believed to be a Paleolake. At topographic points outcrops of Tistung Formation are exposed in the vale. There are few other buried hills and river channel in the vale underlying the thick screen of the vale fill deposits. Kathmandu Valley is situated between latitudes 27i‚°32 ‘ N and 27i‚°49’N and between longitudes 85i‚° 11 ‘ E and 85i‚° 32 ‘ E. The constellation of the vale is more or less round with watershed country of 651 km2. The topographic characteristics of the survey country are gently inclining vale floor, vale field patios with bit faces, and talus cone deposition, together with the inundation fields.
The clime of the country is warming temperate-semitropical, mostly affected by monsoon behaviour. The maximal temperature is observed about 36i‚° C in summer ( May ) and the minimal temperature is about -3i‚°C in winter ( January ) . The major signifiers of precipitation are rain, occasional hail and fog. Sing the precipitation received record the maximal one-year precipitation within the vale was recorded as 3293 millimeter in 1975 and lower limit was 917 millimeter in 1982. The summer rainfall occurs chiefly in the months of June to September and winter rainfall is besides common but non heavy. Kathmandu Valley receives an one-year mean rainfall of about 1600 millimeter, which is besides the mean one-year rainfall for the whole Nepal.
The average comparative humidness is 75 % and the average air current speed rises till the month of May up to average of 0.55 m/s and lessenings after monsoon until December. The prevailing air current waies are west and northwest. By and large the yearss are instead unagitated before midday and the air current rises afternoon. The monthly air force per unit area is about changeless throughout the twelvemonth, which is about 860 megabit. The sunshine continuance is in the scope between 7 hours and 9.5 hours per twenty-four hours except during the months of monsoon. The mean one-year evapotranspiration is 829 millimeter over the basin.
The vale is situated at the upstream range of the Bagmati River. The Bagmati River is the chief drainage, which drains all the H2O collected in the vale basin to the South and dissects the mountains of Mahabharat scope at the sou’-west of the vale. It originates from Bagdwar in the Shivpuri Hill in the North and flows from nor’-east to southwest way in the northern half portion of the vale. The watershed country has an intend form of handbill with the mercantile establishment of the basin at Chovar gorge, which is the lone mercantile establishment of the basin. The fluvio-lacustrine sedimentation filled in the vale underside controls the drainage system. The major feeders for Bagmati river are nine in entire viz. Mai khola, Nakhu khola, Balkhu khola, Vishnumati khola, Dhobi khola, Manohara khola, Kodku khola, Godavari khola and Hanumante khola. Hanumante khola flows towards the West and Balkhu khola towards the E. Mai khola and Dhobi khola flow towards the South. They meet Bagmati River in the cardinal portion of the vale. The Vishnumati, the Bagmati and the Manohara khola, which rise from northern and northeasterly of the watershed, fall in in a topographic point called Teku Dovan in Kathmandu City. Godavari khola, the Kodku khola and the Nakhu khola rise in the southern portion of watershed and flow from the South to north to fall in with the Bagmati River.
Hydrogeological status of the vale is of import things to cognize the groundwater potency and its output appraisal. The vale is located in the Lesser Himalayan part in cardinal Nepal. Bedrocks are exposed chiefly in the hill slopes about and merely at few topographic points in the vale. The vale is filled with the fluvio-lacustrine deposits of quaternate age. These deposits were derived from the environing hills. The thickness of the vale fill deposits varies harmonizing to the undulated form of the cellar from 78 m in Bansbari upto 549 m in Bhrikuti Mandap as confirmed by deep dullard holes ( Kaphle and Joshi, 1998 ) . Metasedimentary every bit good as metamorphous stones represent the basement/bedrock of the vale. Shrestha ( 2001 ) assigned The Hydrological Soil Group ( HSG ) for each type of geological formation harmonizing to its infiltration potency as per SCS ( 1975 ) . HSG A was assigned for the dirt of high infiltration rate, B for medium, C for slow and D for really slow rate. The HSG of the vale is shown in Fig.2.
Fig.2 HSG Map of Kathmandu Valley ( Source: Shrestha, 2001 )
There are two types of sediment stuff viz. unconsolidated and somewhat amalgamate deposit stuffs. The unconsolidated stuffs are found largely in the northern portion of the vale and bank of major rivers whereas somewhat consolidated stuffs are found in other parts. In the vale, silty clay lake sedimentation ranges in thickness from 180 to 220 metres or more from surface and are predominate in the centre and South of the vale. On the other manus no midst silty clay lake sedimentation exists in the northern vale except deep part of Dhobi khola good field. Un-confined to semi-confined sand and crushed rock formation predominate in the North and nor’-east of vale. These formation ranges in thickness from 30 to 80 m with high permeableness. On the other manus, the confined H2O bearing formation is underlined the above mentioned really thick silty clay in the centre and south vale. However this deep aquifer has low permeableness and high electrical conductance. The land H2O Wellss in the north side have penetrated high permeable H2O bearing formation. However, the inactive H2O degree in good field as observed by Nepal Water Supply Corporation ( NWSC ) has been demoing a diminution tendency since the groundwater development has started. Almost all the private Wellss are located in the centre and South of the vale, drilled into the confined low permeable aquifer underlined the really thick silty clay formation. In the centre of the vale, below Quaternary sedimentary formation, pre-Palaeozoic difficult fresh stones are confirmed by gas Wellss at 450 m below land surface.
GROUNDWATER ZONE AND RECHARGE
Recharge into groundwater is a complicated phenomenon particularly when sing recharge in a deep aquifer. It depends on many factors such as dirt, flora, geographics, and the hydrological conditions. In general, most of rechargeable countries are confined in high level fields and alluvial low fields in the vale, because the development of groundwater seems to be hard in the environing high mountains. The mountain ranges environing the vale have no possibility for groundwater recharge because of the high alleviation topographical conditions. Due to immerse incline, the rainfall will change over rapidly to runoff than infiltrate through the land and joins the nearest feeders. Most of the permeated rainfall moves laterally and reappears in to the river channel as base flow or lost as evapotranspiration. The staying portion moves vertically and recharges the groundwater basin. So the rechargeable countries are found on the borders of northern and southern portion of the groundwater basin boundary. Groundwater basin boundary has country of 327 km2 ( Shrestha, 1990 ) . The entire rechargeable country in the vale was found 86 km2 which is 26 % of the groundwater basin country. The sum of long term mean one-year groundwater recharge to the Kathmandu Valley basin was estimated as presented in Table 1.
Table 1. Recharge Amount in tantamount deepness over the Kathmandu Groundwater Basin
( Shrestha, 1990 )
Recharge sum in tantamount deepness over the basin per twelvemonth
Recharge Calculation Methods
Water Balance Method
Base flow separation Method
Specific Yield Method
Chloride Balance Method
Groundwater Flow Method
In 1972, the incoming tritium content at Kathmandu vale was estimated by the Atomic Energy Research Establishment ( AERE ) , Harwell, 60 TU ( Tritium unit ) during summer and 30 TU in winter. The Tritium dating consequence for the groundwater indicated the recharge H2O was of pre-1954 ( Binnie & A ; Partners and Associates, 1973 ) .
Based on hydrogeological construction the vale can be divided into three groundwater zone, viz. Northern, cardinal and southern zone.
The northern zone includes 5 well Fieldss ( Bansbari, Dhobikhola, Manohara, Bhaktapur and Gokarna good field ) as chief H2O beginnings and of 157 km2 country with estimated recharge country of 59 km2 ( Shrestha, 1990 ) . The northern zone is largest recharge country of the vale. There are unconsolidated high permeable stuffs sedimentations in upper portion dwelling of micaceous vitreous silicas, sand and crushed rock. It can give big measure of H2O. Isotope analysis survey made by Jenkins et Al, 1987, confirmed that there is more rapid and vigorous recharge in Sundarijal country ( Gokarna good field ) than elsewhere. This zone is an interbedded aquifer or a series of sub aquifers and the complexness of its construction. It has mean transmissivity in scope of 83 to 1963 m3/d/m and low electrical conduction in the scope of 100 to 200 ms/cm.
The cardinal zone includes most of nucleus urban country with about all private Wellss. This zone includes Mhadevkhola good field. The upper portion of sedimentation is composed of impermeable really thick stiff black clay with brown coal. Entire groundwater basin under cardinal zone is 114.5 km2 and the rechargeable country under this zone is 6 km2. It has mean transmissivity in the scope of 32-960 m3/d/m and really electrical conduction of an norm of 1000 ms/cm. The being of soluble methane gas gives an indicant of sustended aquifer conditions.
The southern zone is characterized by about 200m thick clay formation and low permeable basal crushed rock. This zone is non good developed and merely recognized along the Bagmati River between Chovar and Pharping. Entire groundwater basin under this zone is 55.5 km2 and the rechargeable country is 21 km2. This zone includes Pharping Well field.
WATER SUPPLY MANAGEMENT STATUS IN KATHMANDU VALLEY
4.1 Institutional Set up and Service Area
The H2O supply services of Kathmandu Valley have remained hapless despite assorted efforts through many undertakings during last three decennaries. It was realized that the hapless province of H2O services in Kathmandu vale was a compounded consequence of lacks in H2O resources, failings in system capacity, insufficiencies in direction efficiency and increasing political interventions after 1990 political alteration. As per understanding made with ADB for Melamchi Water Supply Project ( MWSP ) , the Government of Nepal restructured the bing merely one State owned regulator and operator, Nepal Water Supply Corporation ( NWSC ) and set uping three separate entities, each for the function of plus ownership and policy scene ( Kathmandu Valley Water Supply Management Board ( KVWSMB ) , operation and direction of services ( Kathmandu Upatyaka Khanepani Limited ( KUKL ) and economic ordinance of the services ( Water Supply Tariff Fixation Commission ( WSTFC ) . KVWSMB issued an operating licence to KUKL for 30 old ages on 12 February 2008 and besides signed plus rental understanding for 30 old ages. Under the Asset Lease Agreement, KUKL has sole usage of leased assets for the intent of supplying H2O services over 30 old ages and is responsible for keeping the leased assets in good working status, fixing capital investing and plus direction plans to run into the service criterions specified in the licence and implementing such investing program as approved by KVWSMB. As supplier of the licence, KVWSMB is besides responsible for supervising whether KUKL complies with the commissariats of the operating licence and plus rental understanding. The service country of KUKL includes 5 Municipalities and 48 VDCs as shown in Fig. 3. Water supply direction for staying 51 VDCs are under Department of Water Supply and Sewerage, Government of Nepal.
4.2 Population Projections
The Kathmandu Valley is the most dumbly populated part in Nepal. Its population has besides been increasing quickly. This population is mostly in Kathmandu, which is the Centre of disposal, industrial, commercial, societal and economic activities. During the last three decennaries, the growing in population has been significantly driven by immigration. The immigration is mostly due to better employment and concern chances, better educational and medical installations, but besides insurgence and security concerns of recent old ages.
Fig. 3. Kathmandu Valley and KUKL service country
( Beginning: KUKL 2011 Third Anniversary Report, 2066/67 )
The rapid unplanned urbanisation of the Kathmandu Valley has brought negative impact to its overall development. Water became scarce as demand exceeded supply. Lack of operational effluent system installations converted the holy Bagmati River into a extremely polluted river. Congested and crowded roads brought adversity to travellers and route junctions became garbage dumping sites. Despite these negative impacts, the urbanisation of the vale has still continued at a similar rate to the past 10 old ages. Harmonizing to urban contrivers, from urban basic service direction and catastrophe alleviation direction facets, the Kathmandu Valley merely has a transporting capacity of 5 million populations.
In 1999, the Ministry of Population and Environment ( MOPE ) estimated that the population in 1998 was 1.5 million, presuming an urban growing rate of 6.3 % and 2.32 % for the rural sector. This is consistent with the 2001 Census of 1.67 million. Using separate growing rates for the urban and rural population, the population of the vale was estimated to make 3.5 million by 2016 under a “ do-nothing scenario ” harmonizing to MOPE ( 1999 ) , as shown in Table 2.
Table 3 shows the jutting population in the Kathmandu Valley and KUKL service country upto 2025. Population in Kathmandu Valley will be saturated with maximal capacity of 5 1000000s in 2025. Thus surrogate planning and development of urban colonies are needed after 2025.
Figure 4 shows comparing of the KUKL service country lasting population projections adopted with those provided by SAPI ( 2004 ) and the Bagmati Action Plan ( BAP ) ( 2009 ) . The BAP projection is higher because the country taken is for the whole of the Kathmandu Valley and includes countries outside the KUKL service country.
Table 2. Population Projection for Kathmandu Valley under “ Do-nothing Scenario ”
Note: 1 Growth rate at 6 % per annum, 2, Growth rate at 2.32 % per annum.
Urban population includes municipal population and population of 34 quickly urbanizing VDCs, Source: MOPE, 1999
Table 3: Projected Population for Kathmandu Valley and KUKL Service Area Year
2001 ( nose count )
KUKL Service Area
Beginning: Kathmandu Valley Water Supply & A ; Wastewater System Improvement ( PPTA 4893- NEP ) May 2010 )
WATER INFRASTRUCTURES ( KUKL )
Figure 5 shows 6 major H2O supply strategies, viz. , Tri Bhim Dhara, Bir Dhara, Sundarijal, Bhaktapur, Chapagaun, and Pharping strategies, which include surface and groundwater beginnings, WTPs, and major transmittal lines.
Surface Water Sources: At nowadays, there are 35 surface beginnings being tapped for H2O supply largely situated at hills environing the vale as spring in the vale. There is considerable seasonal fluctuation in H2O discharge. Most H2O beginnings have a reduced flow in the dry season by 30 to 40 % with some by every bit much as 70 % . Almost all the beginnings have some possible extra output in the moisture season. The entire moisture season supply of 106 MLD reduces in the dry season to 75 MLD.
Groundwater Beginnings: Deep tubing Wellss are the chief agencies of pull outing groundwater for usage in the H2O supply system. Out of 78 bing deep tube-wells merely 57 are presently in operation chiefly from 7 good Fieldss, viz. , Manohara, Gokarna, Dhobikhola, Bansbari, Mahadevkhola, Bhaktapur, and Pharping good Fieldss. Most of the tubing wells electro-mechanical parts are in a hapless status with most flow metres losing or broken. Tube Wellss used to be operated merely in the dry season in order to supplement cut downing surface H2O beginnings, but, due to demand transcending supply, they are now besides used in the moisture season. Entire dry season ( 4 months: February to May ) rated production 33 MLD with a reduced moisture season ( staying 8 months ) production of 13.7 MLD. Additional subsurface flow has been pull outing through 15 dug Wellss. Table A1 ( in Appendix ) presents stock list of deep tubewells presently in runing status in KUKL.
Fig.4. Population Projections by Assorted Studies ( Beginning: Kathmandu Valley Water Supply & A ; Wastewater System Improvement ( PPTA 4893- NEP ) , MPPW/ADB, May 2010 )
Water Treatment Plants: At nowadays, there are 20 H2O intervention workss ( WTPs ) in the system with a entire intervention capacity of about 117 MLD handling surface H2O and groundwater due to high Fe content. Six WTPs are of capacity between 3 to 26.5 MLD. The largest is at Mahankal Chaur with a intervention capacity of 26.5 MLD and the smallest is at Kuleswor with a intervention capacity of 0.11 MLD. Most of the WTPs are in hapless status and none has operational flow metres or decently runing chlorination equipment.
Service Reservoirs: There are a sum of 43 service reservoirs in the system with capacities runing from 4,500m3 down to 50m3. Most of the reservoirs are in sensible status but two are leaking. The entire storage capacity is 41500 M3.
Pumping Stations: There are 31 H2O supply pumping Stationss in the system that are used to pull H2O from sump Wellss to intervention workss or service reservoirs, and to make full up reservoirs located on higher land or overhead armored combat vehicles. Of these lone 11 are in satisfactory status. Few have operational flow metres or force per unit area gages. Major operation and care job in the pumping Stationss are deficiency of skilled technician and absence of proper monitoring mechanisms.
Transmission Mains and Distribution Lines: At nowadays, the entire length of transmittal brinies is about 301kms, aging between 20 to 115 old ages, and distribution brinies of about 1115 kilometer of aging between 2 to 115 old ages, with pipe diameter changing from 50mm to 800mm. The pipe stuffs used include Galvanized Iron ( GI ) , Cast Iron ( CI ) , Steel ( SI ) , Ductile Iron ( DI ) , High Density Polythene Pipe ( HDPE ) and Polyvinyl Chloride ( PVC ) . The bulk type of pipe used is 50mm diameter GI.
Fig.5. Location of Reservoirs, H2O beginnings and WTPs
Operating Mechanism: The system has approximately 1300 major valves of different sizes. Most of the big sizes valves are situated inside WTPs and runing daily. All valves are being operated manually. Water escape from the valve chamber or valves contributes major part in the sum counted leakage per centum. Other than piped H2O supplied through the valves, H2O oilers are besides functioning H2O particularly in H2O scared country by shooting into the distribution line normally smaller size ( 50 millimeter ) and make fulling in publically established polytanks. Water oilers are besides being used for exigency status such as grapevine breakage, fire combat and sudden malfunctioned systems. Water oilers are besides used as private trip bear downing approved rate. There are many jobs in the distribution system. These jobs include: ad hoc laying of pipes and valves, engagement of users ‘ group and their intercession in the operation of valves, multiple service grapevine connexions, direct pumping from distribution lines, illegal connexions, high per centum of escape and wastage, and direct distribution from transmittal brinies. The bulk of consumer lines are leaking at the connexion to the distribution brinies and few clients have decently runing consumer metres.
WATER Demand AND GROUNDWATER USE FOR SUPPLY
6.1 Current Water Demand and Supply
Water demand is normally derived from the population within service country, population growing, domestic H2O ingestion degree premises, and a proviso for non-domestic H2O ingestion. The lasting population is forecast to lift from present population of 2.1 million in 2010, 2.7 million in 2015 and 3.2 million in 2020 and 3.9 million in 2025. Out of the entire population forecast 77 % , 87 % and 96 % of the population will be served, as a consequence of the MWSP and future investings, in 2015, 2020 and 2025 severally. Predicting the exact figure of impermanent population in the vale is a ambitious undertaking, as there is no dependable informations. Kathmandu Valley Water Supply & A ; Wastewater System Improvement-PPTA 2010, undertook a sample study to number impermanent population. The sample studies were focused on three classs of the impermanent population viz street sellers ; pupils, service holders and labors seeking occupation in the vale ; and house servants/keepers. The study indicated that impermanent population amounted to about 30 % of the lasting population. The proportion of impermanent population varies between municipal and VDC wards. It has to be taken into history in population projections and service demands.
However, demand is besides a map of monetary value, household income handiness and handiness of H2O supply, but accurate estimations of the impact of these factors require extended analysis of historical informations. The present lasting population of the valley H2O supply service country is estimated at over 2.1 million. Adding 30 % the entire population to be considered for gross demand prediction will be 2.73 million. It is sensible to presume 40 % of entire H2O ingestion rate for impermanent or drifting population. Sing family sanitation system in the service country, it is sensible to take per capita demand in the scope of 85 to 95 lpcd. Kathmandu Valley Water Supply & A ; Wastewater System Improvement-PPTA, 2010, has considered 93 lpcd. For the demand taking 135 lpcd which is ingestion rate considered in MWSP for entire population including impermanent population, the entire H2O demand at service degree or point of usage is found to be 315 MLD, which is similar to KUKL estimated demand of 320 MLD ( KUKL, 2011 ) . Estimated unaccounted for H2O ( UfW ) considered for the system is 35-40 % ( KUKL 2011 ) . Sing UfW as 40 % , net H2O supply would be decreased by 40 % .
Figure 6 shows maximal production of 149 MLD on the month of September and lower limit of 89 MLD on March. It gives annual mean production of 119 MLD and dry season mean production of 94 MLD whereas wet season norm is 131 MLD.
Sing 20 % existent losingss as process loss on H2O flow integrating transmittal loss, intervention works operation loss, measure of H2O supplied and lacks is estimated as shown in Fig.7 and Table 4. 20 % loss is assumed to be occurred in distribution system, i.e. from service reservoir to a pat or point of usage.
Fig.6. Average Daily Surface and Groundwater Production ( KUKL, 2011 )
Table 4. Current Average Monthly Demand, Supply and Lacks
114 ( 13.5 )
99 ( 33 )
89 ( 33 )
95 ( 33 )
96 ( 33 )
114 ( 13.5 )
141 ( 13.5 )
145 ( 13.5 )
149 ( 13.5 )
142 ( 13.5 )
132 ( 13.5 )
116 ( 13.5 )
( aˆ¦ ) Groundwater part in MLD
Figure 7 shows dry season mean supply as 76 MLD and 105 MLD for moisture season. Annual mean supply is 96 MLD. Thus the H2O supply in the Kathmandu Valley via KUKL piped web at nowadays is an mean 35 liters per capita per twenty-four hours, whereas supply in KUKL service country is mean of 46 lpcd.
6.2 Groundwater Depleting Trends
The part of groundwater part in entire production is an norm of 35 % during dry season ( 4 months from Feb to May ) and 11 % during moisture season ( staying 8 months ) . The pumping rate of the private Wellss in the vale is smaller compared to KUKL ‘s tubewell abstraction. The tendency of groundwater extraction volume from private Wellss and gas Wellss remains about changeless during the last several old ages. But the production from KUKL Wellss is increasing greatly. Deeper groundwater is being over-extracted and extraction is unsustainable. It is estimated that there are over 10,000 manus dug well which are used to supplement the KUKL H2O supply. More dependable H2O supplies will cut down the demand for groundwater pumping, therefore leting more sustainable usage of this valuable H2O resource.
Fig.7. Average Monthly Demand, Supply and Lacks
JICA ( 1990 ) had used historical good hydrographs to measure the seasonal fluctuation of groundwater degree and recharge into chief aquifer in the survey of groundwater direction of Kathmandu Valley. Tank Model ( Sugawara et al.1974 ) was used for simulation to develop the relationship between rainfall and groundwater degree. The one-year fluctuations ( maximal groundwater level- minimal groundwater degree ) of long-run norm at two sites were estimated. In the survey, they estimated average one-year fluctuation on well WHO 7A ( Sundarijal ) by taking norm over the period 1940-1986 as 1500mm and on good B12 ( Maharajgunj ) over 1947-1975 as 457 millimeter. Both Wellss are located in the northern portion of the basin. The groundwater degree has an one-year rhythm.
The Kathmandu Valley groundwater basin can be isolated from other groundwater organic structures outsides the vale. The recharge through outside the vale is assumed to be negligible. The groundwater degrees have been in about steady status in the early phases of the 1980 ‘s, because no big good was operated at that clip in the basin. JICA ( 1990 ) has developed relationship by trial-and-error method in order to do the deliberate groundwater degree of the chief aquifer to co-occur with the ascertained 1. Extraction of groundwater by pumping has found to be increased since 1984 so it is deserving to presume that groundwater degree was in a steady province status on and before 1983.
Groundwater appraisal theoretical account developed by Shrestha ( 2001 ) , has found groundwater flat diminishing aggressively from 1985 onwards and balanced H2O available was suddenly changed from 1986 onwards. The theoretical account had assumed initial groundwater storage as 1000mm to cipher comparative drawdown of the groundwater. The theoretical account predicted the maximal dirt wet content as 225 millimeter which had been found in the scope of 200 millimeters to 250mm estimated by Binnie & A ; Partners and Associates ( 1973 ) for the Kathmandu Valley. He used average one-year existent evapotranspiration calculated by Shrestha ( 1990 ) , as 829 millimeter while the average one-year possible evapotranspiration was 1074 millimeter. An one-year existent evapotranspiration was found about changeless for the vale. Some recharge countries, which are on the northern portion of the vale, is change overing to urbanisation quickly. On the other manus, extraction of groundwater is besides increasing to carry through the demand of H2O. These are the chief grounds for rapid decrease of groundwater storage.
The drawdown was calculated with mention to the twelvemonth 1975. The initial status of groundwater degree is taken as of the twelvemonth 1972. The drawdown deepness observed in the vale basin was much closed with ascertained drawdown for all ascertained old ages. The theoretical account has found three distinguishable tendencies of drawdown such as diminishing tendency from 1977 to 1981, increasing tendency from 1981 to 1985 and crisp increasing tendency after 1986. Main grounds behind crisp increasing tendency of drawdown were listed as three to four crease increasing in new house buildings and over extraction of groundwater to get by hiting H2O demand due to rapid and unplanned urban growing. The entire basin tantamount drawdown was found to be increased by 2.75 m in twelvemonth 1984 and 7.5 m in twelvemonth 1989 when compared to that in the twelvemonth 1978. The theoretical account predicted drawdown merely due to groundwater extraction was found to be increased by 2 m in the twelvemonth 1984 and 6m in the twelvemonth 1989 compared with the drawdown during 1978. Shrestha ( 2001 ) concluded that drawdown of 0.75m in the twelvemonth 1984 and 1.5 m in the twelvemonth 1989 could be attributed to the hydrological alteration due to land-use alterations.
POST MELAMCHI SCENARIO AND EXPECTED STRESS IN FUTURE
It will be sensible to presume that The Melamchi H2O will be served its first stage to the back street by 2016. Harmonizing to the anticipation ( Mentioning Figure 4 ) , the lasting population of the service country will be 2.8 1000000s in 20016. Harmonizing to urban contrivers, from urban basic service direction and catastrophe alleviation direction facets, the Kathmandu Valley merely has a transporting capacity of 5 million populations and it would traverse the capacity by 2025.
MWSP is a comprehensive multi giver H2O supply mega undertaking that aims to better the wellness and wellbeing of the people in Kathmandu Valley. It will accomplish this impact by deviating H2O from the Melamchi River to the Kathmandu Valley and therefore present its overall result of relieving the chronic deficit of drinkable H2O. MWSP is implemented under two subprojects. Subproject-1 delivers bulk drinkable H2O to the caput of the Kathmandu Valley ( Melamchi Diversion Scheme ) . Its major civil constituents are the 26 kilometer tunnel and the new H2O intervention works at Sundarijal. MWSP subproject-2 has major civil constituents of H2O distribution system and effluent system betterments in the vale. MWSP has aimed for 24 hours H2O supply of 135 lpcd and structured H2O substructure rehabilitation and development plans under subproject-2 as listed below, to cut down UfW to 20 % from 40 % . It can be divided into two parts. 10 % loss is assumed to be occurred in transmittal and intervention procedure and another 10 % in distribution system.
Rehabilitation and Development of Surface Water and Groundwater Beginnings
Rehabilitation and Development of WTPs
Bulk Distribution System
Water Supply Service reservoirs fix and New building
Distribution Network Improvement ( DNI )
Land Acquisition for the plans
MWSP has been conceived to deviate 510 MLD of H2O to the Valley in three stages. In the first stage a sum of 170 MLD of H2O would be diverted and followed by subsequent development of Yangri and Larke river system to the melody of 170 MLD each in following two stages. It is expected that first stage Melamchi Water will be added in 2016 and other add-ons of 170 MLD in 2019 and in 2025.
Table.5.Pre and Post Melamchi Scenario on Demand, Production, Supply, Groundwater Contribution and Supply Hour per twenty-four hours for 2011 and 2016
Table 5 nowadayss deliberate H2O demand after first stage of MWSP completion i.e. on 2016, as 423 MLD functioning lasting population of 2.8 million and impermanent population of 0.84 million ( 30 % of lasting population ) with 135 lpcd 24 hr supply. Average Water Production including extra 170 MLD with mean groundwater part of 7 % is 288.96 MLD. Supply is calculated sing 10 % transmittal and intervention procedure loss and mean supply as 260.06 MLD. Liter per capita per twenty-four hours ( lpcd ) is evaluated sing supply measure for entire effectual population ( 2.8 +0.3 x 2.8 = 3.64 1000000s ) , but merely 40 % of ingestion rate is considered for impermanent population. It shows an mean lpcd of 82.9 lpcd functioning the entire population with 24 hr supply. If supply is managed with project demand of 135 lpcd, the mean supply continuance per twenty-four hours will be of 14.74 hours.
Table.6.Pre and Post Melamchi Scenario on Demand, Production, Supply, Groundwater Contribution and Supply Hour per twenty-four hours for 2019 and 2025
Figure 8 shows the MWSP will increase mean lpcd from 40 lpcd in 2011 to 126 lpcd in 2025. If supply system is managed with project demand of 135 lpcd, the mean supply continuance per twenty-four hours is besides increased from 7 hours a twenty-four hours in 2011 to 23 hr a twenty-four hours in 2025. Table 6 Figure 9 show reduced mean groundwater part from 19 per centum in 2011 to 3 per centum in 2025.
Fig.8. Average Supplied lpcd increasing with MWSP
Fig.9. Percentage Groundwater Contribution in Supply
Sing H2O supply scenario of 2011, mean H2O supplied at the point of usage will be 57 MLD taking 40 % UfW ( KUKL, 2011 ) and ingestion rate of the supply is 24.27 lpcd. Supply continuance per twenty-four hours is calculated as 4 hr if considered 135 lpcd. But the supply hr is much less than calculated as present status of KUKL H2O supply. Major possible grounds which make difference with existent conditions might be listed as:
Inaccurate prediction of served population
Absence of effectual MIS of Water Supply System
Inaccurate gauging UfWs ( transmittal, intervention and distribution )
It is found that MWSP entirely is non sufficient supplying H2O supply to cover forecasted served populations. Alternate beginnings should be planned and added. Another option will be, if outside the valley urban colony development planning is formulated and implemented, the population growing rate will be controlled or it may be decreased chiefly due to migration of new population to outside the vale.
Consequence of land-use alteration is more prevailing in groundwater than on the surface H2O ( Shrestha, 2001 ) . This is due to fact that the extraction of groundwater to carry through the demand of growing urbanisation is increased and part of H2O infiltrating for groundwater is reduced due to increase in impenetrability. Hence rechargeable country of the vale significantly northern groundwater zone should hold land usage be aftering supplying more unfastened country with less paved.
To command rapid drawdown of groundwater degree, inordinate extraction of deep groundwater should be controlled supplying surrogate options such as presenting rainwater reaping techniques from micro ( private ) to macro ( institutional ) degree, and H2O demand direction. Riverhead woods environing the bing surface beginnings should be protected so that relentless surface flows could be observed throughout the twelvemonth.
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