The Wa­ter Re­sources of Pak­istan

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Rain­fall in Pak­istan is markedly vari­able in mag­ni­tude, time of oc­cur­rence and its aerial dis­tri­bu­tion. How­ever, al­most twothirds of the rain­fall is con­cen­trated in the three sum­mer months of July - Septem­ber. The mean an­nual pre­cip­i­ta­tion ranges from less than 100 mm in parts of the Lower In­dus Plain to over 750 mm near the foothills in the Up­per In­dus Plain.

There are two ma­jor sources of rain­fall in Pak­istan: the Mon­soons and the Western Dis­tur­bances. The rel­a­tive con­tri­bu­tion of rain­fall in most of the canal com­mands is low when com­pared with the two other sources of ir­ri­ga­tion wa­ter i.e., canal wa­ter and ground­wa­ter. More than 60% of the kharif sea­son rain­fall is con­cen­trated in the month of July for al­most all of the canal com­mands.

The Mon­soons orig­i­nate in the Bay of Ben­gal and usu­ally reach Pak­istan, af­ter pass­ing over In­dia, in early July. They con­tinue till Septem­ber. The In­dus Plains re­ceive most of their rain­fall from the Mon­soons. There are two pe­ri­ods of thun­der­storms in Pak­istan: (1) April-June (2) Oc­to­ber-Novem­ber. Th­ese pe­ri­ods are the dri­est parts of the year, par­tic­u­larly Oc­to­ber and Novem­ber. Dur­ing this time, thun­der­storms caused by con­vec­tion bring spo­radic and lo­cal­ized rain­fall.

WA­TER SEC­TOR DE­VEL­OP­MENT

Pak­istan lies in an arid and semi-arid cli­mate zone. The en­tire In­dus Plains (canal com­mand ar­eas) re­ceive an aver­age sea­sonal rain­fall of 212 mm (95% con­fi­dence in­ter­val ± 28) and 53 mm (95% con­fi­dence in­ter­val ± 8) in the kharif and rabi sea­sons, re­spec­tively.

The rain­fall varies as we move from the north and north­east to the south of the coun­try. It is only the canal com­mand ar­eas in the Khy­ber Pakhtoon Khawa prov­ince (KPK) and the north­ern-most canal com­mands of the Pun­jab prov­ince that re­ceive some ap­pre­cia­ble amount of rain­fall dur­ing the sum­mer as well as the win­ter sea­son. The canal com­mands up­stream of the rim sta­tions (i.e., in the KPK) re­ceive al­most 55% of their an­nual rain­fall dur­ing the kharif sea­son. The canal com­mands in the Up­per and Lower In­dus Plains re­ceive 75% and 85- 90% of the an­nual rain­fall re­spec­tively, dur­ing the kharif sea­son. The an­nual vari­abil­ity of rain­fall in­creases as one moves south. The canal com­mand ar­eas of Guddu and Sukkur Bar­rages fall in an area where vari­abil­ity is the high­est.

Based on 10-year aver­age (1990-1999), data from the Pak­istan Me­te­o­ro­log­i­cal Depart­ment of an­nual rain­fall in some of the ma­jor cities is as fol­lows:

GLACIER

The catch­ment area of the In­dus Basin con­tains some of the largest glaciers in the world, out­side the Po­lar Re­gions. The glacial area of the up­per In­dus catch­ment is about 2,250 km2 and ac­counts for most of the river runoff in sum­mer.

The Kabul River, which is mainly snow-fed, orig­i­nates from the Unai Pass of the South­ern Hin­dukush at an el­e­va­tion of 3,000m above sea level (masl). It drains eastern Afghanistan and then en­ters Pak­istan just north of the Khy­ber Pass.

The Jhelum River rises in Kash­mir at a much lower el­e­va­tion than the source of the In­dus River. It falls much less rapidly than the In­dus River af­ter en­ter­ing Pak­istani ter­ri­tory. The Chenab River orig­i­nates in the Hi­machal Pardesh in In­dia, at an el­e­va­tion of over 4,900 masl. It flows through Jammu in In­dian-held Kash­mir and en­ters Pak­istani ter­ri­tory up­stream of the Mar­ala Bar­rage.

The snow and ice melt from the glacial area of the Up­per In­dus catch­ment sup­ply ap­prox­i­mately 80% of the to­tal flow of the In­dus River in the sum­mer sea­son. The an­nual flows in the Kabul River are less than one-third of that in the In­dus River. How­ever, the Kabul River starts to rise ap­prox­i­mately a month ear­lier than the main stem of the In­dus. Its flows are of sig­nif­i­cance for ful­fill­ing the late-rabi early-kharif (March to May) ir­ri­ga­tion re­quire­ments of the canals.

Snowmelt ac­counts for more than 50% of the flow in the Jhelum River. How­ever, the Jhelum is much more de­pen­dent than the In­dus on the vari­able mon­soon runoff. Both, the Jhelum and Chenab River catch­ments can si­mul­ta­ne­ously be in­flu­enced by the Mon­soons. Since the Chenab River rises at higher al­ti­tudes, snowmelt ac­counts for a con­sid­er­able pro­por­tion of its runoff.

RIVERS AND DAMS

The em­bry­onic In­dus river sys­tem, which is the main source of sur­face wa­ter in Pak­istan, most likely was cre­ated some fifty mil­lion years ago, when the In­dian Plate (Gond­wana­land) first col­lided with Eura­sia (An­gar­a­land). Be­tween the two plates was the Tethys Sea, which was shal­low and sandy and up-folded to form the great Hi­malayan Moun­tains in the Mesozoic era. Th­ese moun­tains, their un­bro­ken snow cover, have be­come the pri­mary source of wa­ter to the In­dus sys­tem.

The aver­age an­nual flow-rates of ma­jor rivers has been cal­cu­lated be­tween 1922-61 to in­di­cate wa­ter flows be­fore the In­dus Wa­ter Treaty, 19851995 to in­di­cate the post-treaty flows and the 2001-02 flows to present the cur­rent sit­u­a­tion of drought con­di­tions. Th­ese are pre­sented in the ta­ble be­low.

The his­tory of dam con­struc­tion in Pak­istan is rel­a­tively short. The peren­nial River In­dus ful­filled the ir­ri­ga­tion needs and the drink­ing wa­ter sup­ply was served by tap­ping the vast un­der­ground wa­ter reser­voir. Be­fore in­de­pen­dence, there were only three dams in Pak­istan, and none on the ma­jor rivers. Two of the dams were in the wa­ter scarce area of Balochis­tan i.e. the Khushdil Khan Dam – 1890 and the Spin Karaiz – 1945. The Na­mal Dam, 1913 was lo­cated in the Mian­wali dis­trict of the Pun­jab.

The con­struc­tion of dams in Pak­istan was ini­ti­ated in 1955, when the coun­try was fac­ing an acute power short­age. Work on the Warsak Dam on Kabul River near Pe­shawar was un­der­taken.

Later, when In­dia stopped wa­ter sup­plies to the net­work of canals in Pak­istan, it be­came im­per­a­tive to build large stor­ages and link canals to restore wa­ter to the af­fected canal sys­tem. This re­sulted in the con­struc­tion of two gi­gan­tic dams, Mangla with a gross stor­age ca­pac­ity of 5.88 MAF and Tar­bela with 11.62 MAF, as a part of the In­dus Basin Re­place­ment Works. Apart from re­place­ment works, a num­ber of rel­a­tively smaller

schemes of ir­ri­ga­tion and wa­ter sup­ply dams were also un­der­taken.

SUR­FACE WA­TER

The ac­count­ing of sur­face wa­ter re­sources in the In­dus Sys­tem is based on river in­flows mea­sured at Rim Sta­tions. A rim sta­tion, in the con­text of the In­dus Basin Ir­ri­ga­tion Sys­tem, is de­fined as a con­trol struc­ture (reser­voir, bar­rage, etc.) on the river just when the river en­ters into Pak­istani ter­ri­tory or up­stream of the canal-ir­ri­gated In­dus Plains of Pun­jab and Sindh Prov­inces.

The rim sta­tions for the In­dus Sys­tem rivers are the Kal­abagh Bar­rage (or some­times Tar­bela Reser­voir) for the main In­dus River, Mangla Reser­voir for the Jhelum River, Mar­ala Bar­rage for the Chenab River and Bal­loki and Sule­manki Bar­rages for the Ravi and Sut­lej Rivers.

The In­dus River and its trib­u­taries, on an aver­age, bring 154 MAF of wa­ter an­nu­ally. This in­cludes 144.91 MAF from the three Western rivers and 9.14 MAF from the Eastern rivers. Most of this, about 104.73 MAF, is di­verted for ir­ri­ga­tion. 39.4 MAF flows to the sea and about 9.9 MAF is con­sumed by the sys­tem losses which in­clude eva­po­ra­tion, seep­age and spills dur­ing floods.

The flows of the In­dus and its trib­u­taries vary widely from year to year and within the year. As is the case with the wa­ter avail­abil­ity, there is sig­nif­i­cant variation in an­nual flows to the sea.

The wa­ters of the In­dus Basin Rivers are di­verted through reser­voirs/bar­rages into canals, clas­si­fied as Main Canals. Th­ese main canals then dis­trib­ute the ir­ri­ga­tion wa­ter into their com­mand ar­eas through a net­work of branch canals.

The In­dus Basin Ir­ri­ga­tion Sys­tem com­prises of three ma­jor reser­voirs, 16 bar­rages, 2 head­works, 2 siphons across ma­jor rivers, 12 in­ter­river link canals, 44 canal sys­tems (23 in Pun­jab, 14 in Sindh, 5 in KPK and 2 in Balochis­tan) and more than 107,000 wa­ter cour­ses. The ag­gre­gate length of the canals is about 56,073 km. In ad­di­tion, the wa­ter­courses, farm chan­nels and field ditches cover an­other 1.6 mil­lion km. The sys­tem uti­lizes over 41.6 MAF of ground­wa­ter, pumped through more than 500,000 tube wells, in ad­di­tion to the canal sup­plies.

Out­side the In­dus Basin, there are smaller river basins. One on the Mekran coast of Balochis­tan drains di­rectly into the sea and a closed basin (Kha­ran). Th­ese in to­tal amount to an in­flow of less than 4 MAF an­nu­ally.

GROUND­WA­TER – HIS­TORIC DE­VEL­OP­MENT

Be­fore the in­tro­duc­tion of wide­spread ir­ri­ga­tion, the ground­wa­ter ta­ble in the In­dus Basin var­ied from about 40 feet in depth in Sindh and Bahawalpur ar­eas to about 100 feet in Rachna Doab (the area be­tween Ravi and Chenab Rivers).

Af­ter the in­tro­duc­tion of weir-con­trolled ir­ri­ga­tion, the ground­wa­ter ta­ble started ris­ing due to poor ir­ri­ga­tion man­age­ment, lack of drainage fa­cil­i­ties and the re­sult­ing ad­di­tional recharge from the canals, dis­tribu­taries, mi­nors, wa­ter cour­ses and ir­ri­ga­tion fields. At some lo­ca­tions, the wa­ter ta­ble rose to the ground sur­face or very close to the sur­face caus­ing wa­ter-log­ging and soil salin­ity, re­duc­ing pro­duc­tiv­ity.

In the late 1950s, the Pak­istan govern­ment em­barked upon a pro­gramme of Salin­ity Con­trol and Recla­ma­tion Projects (SCARPS) wherein large deep tube wells were in­stalled to con­trol the ground­wa­ter ta­ble. Over a pe­riod of about 30 years, some 13,500 tube­wells were in­stalled by the govern­ment to lower the ground­wa­ter ta­ble. Of th­ese, about 9,800 tube wells were in the Pun­jab.

The projects ini­tially proved to be quite ef­fec­tive in low­er­ing the wa­ter ta­ble but with time, the per­for­mance of the SCARP tube­wells de­te­ri­o­rated. The de­vel­op­ment of deep pub­lic tube wells un­der the SCARPS was soon fol­lowed by pri­vate in­vest­ment in shal­low tube wells. Par­tic­u­larly in the eight­ies, the de­vel­op­ment of pri­vate tube wells re­ceived a boost, when lo­cally man­u­fac­tured in­ex­pen­sive diesel en­gines be­came avail­able. Most of th­ese shal­low tube wells were in­di­vid­u­ally owned.

Now more than 500,000 tube­wells sup­ply about 41.6 MAF of sup­ple­men­tal ir­ri­ga­tion wa­ter ev­ery year, mostly in pe­ri­ods of low sur­face wa­ter avail­abil­ity.

Th­ese tube­wells com­pen­sated the loss of pump­ing ca­pac­ity of the SCARP tube­wells and helped in low­er­ing the wa­ter ta­ble.

STA­TUS OF GROUND­WA­TER IN PAK­ISTAN

The In­dus Basin was formed by al­lu­vial de­posits car­ried by the In­dus and its trib­u­taries. It is un­der­lain by an un­con­fined aquifer cov­er­ing about 15 mil­lion acres in sur­face area. In the Pun­jab, about 79% of the area and in Sindh, about 28% of the area is un­der­lain by fresh ground­wa­ter. This is mostly used as sup­ple­men­tal ir­ri­ga­tion wa­ter and pumped through tube wells. Some ground­wa­ter is saline. Wa­ter from the saline tube wells is gen­er­ally put into drains and, where this is not pos­si­ble, it is dis­charged into large canals for use in ir­ri­ga­tion, af­ter di­lut­ing with the fresh canal wa­ter.

In the last 25-30 years, ground wa­ter has be­come a ma­jor sup­ple­ment to canal sup­plies, es­pe­cially in the Up­per In­dus Plain, where ground wa­ter qual­ity is good. Large scale tube­well pumpage for ir­ri­ga­tion started in the early six­ties.

There are presently more than 500,000 tube­wells in the In­dus Basin Ir­ri­ga­tion Sys­tem (IBIS) and the an­nual pumpage in all canal com­mand ar­eas has been es­ti­mated to be over 50 BCM. Ac­cord­ing to a study, the to­tal ground­wa­ter po­ten­tial in Pak­istan is of the or­der of 55 MAF.

Ma­jor part of the ground­wa­ter ab­strac­tion for ir­ri­ga­tion is within the canal com­mands or in the flood plains of the rivers. How­ever, the amount of ab­strac­tion varies through­out the area, re­flect­ing in­ad­e­quacy/un­re­li­a­bil­ity of sur­face wa­ter sup­plies and ground­wa­ter qual­ity dis­tri­bu­tion.

The qual­ity of ground­wa­ter ranges from fresh (salin­ity less than 1000 mg/l TDS) near the ma­jor rivers to highly saline farther away, with salin­ity more than 3000 mg/l TDS. The gen­eral dis­tri­bu­tion of fresh and saline ground­wa­ter in the coun­try is well known and mapped, as it in­flu­ences the op­tions for ir­ri­ga­tion and drink­ing wa­ter sup­plies.

Pun­jab

About 79% of the Pun­jab prov­ince has ac­cess to fresh ground­wa­ter. Some 9.78 mil­lion acres are un­der­lain with ground­wa­ter of less than 1000 mg/l TDS, 3 mil­lion acres with salin­ity rang­ing from 1000 to 3000 mg/l TDS and 3.26 mil­lion acres with salin­ity more than 3000 mg/l TDS.

Saline wa­ters are mostly en­coun­tered in the cen­tral Doab ar­eas. The Cholis­tan area in south­ern Pun­jab is well known for highly brack­ish wa­ters, which can­not be used for drink­ing pur­poses. Ground­wa­ter with high flu­o­ride con­tent is found in the Salt Range, Kasur and Mian­wali. There are also re­ports of high flu­o­ride con­tent, rang­ing from 65 to 12 mg/l in ground­wa­ter in the Bahawalpur area.

Sam­plings of ground­wa­ter in Jhelum, Gu­jrat and Sar­godha dis­tricts have shown con­cen­tra­tions of ar­senic well above the WHO guide­line value of 50 g/l.

Sindh

Around 28% of the Sindh prov­ince has ac­cess to fresh ground­wa­ter suit­able for ir­ri­ga­tion i.e. the wa­ter has less than 1000 mg/l TDS. Close to the edges of the ir­ri­gated lands, fresh ground­wa­ter can be found at 20 - 25 m depth. Large ar­eas in the prov­ince are un­der­lain with ground­wa­ter of poor qual­ity. In­dis­crim­i­nate pump­ing has re­sulted in con­tam­i­na­tion of the aquifer at many places where the salin­ity of tube­well wa­ter has in­creased. The ar­eas with non-potable, highly brack­ish wa­ter in­clude Thar, Nara and Kohistan. In Tharparkar and Umarkot, the sit­u­a­tion is fur­ther com­pli­cated by the oc­cur­rence of high flu­o­ride in the ground­wa­ter.

KPK

In KPK, ab­strac­tion in ex­cess of recharge in cer­tain ar­eas such as Karak, Ko­hat, Bannu and D.I. Khan has low­ered the wa­ter ta­ble and re­sulted in the con­tam­i­na­tion from un­der­ly­ing saline wa­ter.

Balochis­tan

The Makran coastal zone and sev­eral other basins con­tain highly brack­ish ground­wa­ter. Lo­cal com­mu­ni­ties use ground­wa­ter with TDS as high as 3000 mg/l, for drink­ing pur­poses, as there are no al­ter­na­tives. In Mastung Val­ley, the ground­wa­ter has been found to have high flu­o­ride con­tent. The Makran coast and Kha­ran have also been re­ported to have high flu­o­ride ground­wa­ter.

EX­PEN­DI­TURE

Govern­ment ex­pen­di­ture in the wa­ter sec­tor has ran­domly fluc­tu­ated since in­de­pen­dence, be­cause the al­lo­ca­tion of funds for the de­vel­op­ment of the sec­tor have not ob­served con­sis­tent growth pat­terns. Also, the rel­a­tive pri­or­ity of wa­ter sec­tor has changed dur­ing var­i­ous govern­ment regimes.

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