SWRD

Surface Water Resources Development

The construction of major surface storages in Pakistan has been forestalled now for almost 25 years despite the dwindling capacity of the existing sotrages and the recurring seasonal shortages of irrigation water which are exacerbating the provincial conflicts. In the face of this situation the most pressing needs are:

• Convincing the stakeholders that, surface storages including small and delay action dams are an economic necessity and that their adverse consequences could be mitigated by socially acceptable means. 
• Convincing stakeholders that the benefits of hydropower development needs to be equitably distributed. 
• Ensuring through mutually acceptable mechanisms, that the beneficiaries would not be deprived of their due shares in the water resources.
• To improve and enhance the existing infrastructure for water resources development
• To address these basic needs, the strategic elements that can be consideration are: 
• Impartial research to bring out the adverse impact of the variability in irrigation supplies on the agricultural production and the extent to which the value of water could be enhanced with a regulated supply. 
• Studies to bring out how the adverse environmental impacts of surface storages can be mitigated in a socially and economically viable manner.
• Instituting transparent procedures for water allocation. 

Core Challenges / Issues

Augmenting the quantum of useable water resources is a pressing need for Pakistan in the face of the rising population, which by conservative estimates, would increase by 48 percent between 2000 and 2025. What this implies is that, just to maintain the present level of usage per capital and the productivity per unit water by 2025, the present river diversions for irrigation should increase form 130.76 BCM (106 MAF) to 193 BCM (157 MAF) and the groundwater extraction increase form 59.21 BCM to (48 MAF) to 87.58 BCM (71 MAF). In the next 10 years, 27, 14 BCM (22 MAF) of additional river diversions would be required and ground water extraction has to go up by 12.34 BCM (10 MAF). With the groundwater having almost fully exploited and annual flows of rivers limited to an average 172.70 BCM (140 MAF), it is obvious that Pakistan would be faced with critical water situation by 2025.

Even though large quantities of the river waters are being diverted for irrigation and other uses, they are subject to the wide variations in the fiver flows - which in the absence of adequate regulating capacity of the surface storages cause seasonal water shortages in the irrigation system. These flow variations also result in frequent floods, with large, quantities of water going waste while causing damage to the crops and infrastructure. This situation, representing, the dependence of the irrigation systems on the run-of-the-river flows (with a limited and diminishing capacity for seasonal transfer of water), is not conductive to the most productive use of water for agriculture as ideally irrigation systems have to be demand-based.

There is also ample evidence that large quantities  of water are lost in transit in the irrigation and other systems.

Once the water supplies have been conveyed for their intended use, their utilization is subject to waste and whatever use is made is not the most productive. In agriculture this waste is typified by tails waters and inefficient irrigation practices in some canal command, and in municipal system by the wasteful use of water.

To augment the water supply to meet the growing demands, consideration would therefore be required to:-

• The harnessing of addition surface and groundwater resources, to the extent feasible,
• Minimizing of irretrievable water losses, and
• Demand management.  

Management of Water Resources

The elements of water management, which are likely to impact on the future initiatives are treated below:

 

Federal & Provincial Roles

 

Water being a concurrent subject, both the Federal & Provincial governments have been active in the development and management of the water resources.

 

While historically the Provincial Governments have taken up the development the irrigation system, the "replacement works' under the Indus Water Treaty were constructed by WAPDA, a Federal Agency. WAPDA also took up the construction of Drainage Works for the control of water-logging and salinity, which on completion were handed over for O&M to the provinces. Hydropower development had remained a federal responsibility until recently when the provinces have been allowed to exploit small scale hydro-electric potential. The operation of the storage reservoirs primarily to meet the provincial irrigation demands (with hydropower as a by-product) is controlled by WAPDA.

 

Water Allocation

 

After protracted negotiations, the provinces finally in 1991 agreed to their respective shares in the Indus River waters for diversion into the canal systems. This , based on the seasonally available supplies, is overseen by an inter-provincial body with federal representation - the Indus River System Authority (IRSA). However the allocation of the water received by a province for different uses remains a provincial subject.

 

Control & Management of Floods

 

The control of floods with its country wide impacts is treated federally by the Federal Flood Commission. The construction and maintenance of the flood control work is however looked after by the provinces. The Federal Government through the meteorological department and hydrologic inputs by WAPDA, undertakes flood forecasting and coordinates the activities of the provincial governments in the management of flood.   

Remaining Water Resources Potential

Surface Water Potential

In terms of the quantum of the surface water resources, the flows of Indus and its tributaries, available to Pakistan, are the most significant. The meager and highly variable flows of all other streams, offer only, a limited potential for adding to the stock of water.

Season wise the situation is that during Rabi all the natural river flows are captured, and the diversions are augmented from the storage releases. The out flow to the sea during this season is negligible. During Khairf, however, the river flows exceed the diversion by highly variably amount and end up in the sea.

The water out-flowing to the sea, amounting to 50.60 BCM (41.02 MAF) thus represent a potential source for the future development of the water resources. 

Apart from the water going to the sea, there are large water losses in the irrigation systems. These losses are due to conveyance losses in the distribution system which are lost to evaporation and due to seepage from the conveyance channels and from the fields which constitute groundwater recharge. The seepage that takes place in areas where the groundwater is brakish is not retrievable for reuse and its saving can add to the water resources. 

Groundwater Potential

Recent estimates of the availability and use of groundwater of an acceptable quality indicate that this resource has been heavily exploited. There are indications that in some areas, the annual groundwater pumpage exceeds the safe annual yields and the water table is declining. It is only in small area and under restrictive conditions, that additional use-able groundwater can be exploited. 

In an overall context, the safe groundwater yield is estimated to be 67.85 BCM (55 MAF), whereas the extraction is of the order of 59.21 BCM (48 MAF). Thus the remaining groundwater potential is about 8.63 BCM (7 MAF) representing a possible increase of about 14 per cent only.

Water Resource Development 

Small Scale Water Development 

Apart from the major surface water development based on the flows of Indus and its tributaries, the infrequent flows, in the smaller streams have been developed through traditional means such as Rod Kohi, and more recently attention has been paid to the construction of small dams in the upland areas for local uses. All these developments are typical of water scarce environments and subject to the extreme variability in precipitation. 

Groundwater Development

A significant feature impacting on the country's water resources, has been the massive development of groundwater from the Indus Basin aquifer during the last 40 years. Initial development of groundwater, as a supplement to surface irrigation, was the outcome of the Salinity Control and Reclamation Projects (SCARPs) under which large capacity (60 to 150 lit/sec) tube-wells were installed in the public sector in the irrigated area to control water-logging. From 1960 to 1985 over 15,000 fresh water tube-wells were installed in the SCARPs when such development was relegated to the private sector. The demonstration effect of the SCARP tube-wells, however spurred the development of groundwater in the private sector by the use of small capacity (30 lit/sec) tube-wells From 1964 to 1996, the number of tube-well in the country jumped from 27,000 to 469,546 which represents an average growth rate of 9.4 percent. These private tube-wells 80 percent of which are diesel operated, are mostly located in the canal commands where they supplement the canal supplies. 

Water Resource Development 

Major Surface Water Development

The major surface water development in the country has been based on the use of river waters of the Indus and its tributaries. This development which dates back to the middle of the 19th century was based on diverting the natural river flows. Initially the diversion of high flows was attempted in inundation or seasonal canals, but with progressive weirs or barrages across the rivers by controlling the water levels, make it possible to utilize the low Rabi flows for perennial irrigation and also permitted the transfer of waters across and through other rivers to the distantly located irrigable lands. 

For sharing the international waters of the Indus and its tributaries, the Indus Water Treaty was signed with India in 1960, accordingly to which India acquired the exclusive right to the waters of three Indus tributaries Ravi, Beas and Sutlej, and the irrigation systems in Pakistan dependent on these rivers had to be fed by the Indus and its tributaries, the Jehlum and the Chenab, assigned to Pakistan. This required the construction, with donor support, of the Mangla Dam (reservoir live capacity (6.58 BCM (5.34 MAF), Tervela Dam  (reservoir live capacity 11.59 BCM (9.4 MAF), five barrages eight inter-river link canals, linking the rivers Indus, Jehlum Chenab, Ravi and Sutlej, a syphon under the Sutlej river and remodeling of some existing barrages and link canals. Although these works were regarded as replacement work they also incorporated certain development aspects.

Both the Mangla and Terbela Dams, apart from meeting the irrigation water requirements were used for power generation and presently have an installed capacity of 1000 MW and 3478 MW respectively. These two dams, and the Chashma Barrage in which a small storage element of 0.62 BCM (0.5 MAF) was built in, serve as storages for the inter-seasonal transfer of water for meeting the irrigation requirements during the low flow periods. The Chashma Barrage has also been utilized for power generation and presently a low-head hydro-power station with an installed capacity of 184 MW is under construction.   

Following the construction of the replacement work under the Indus Water Treaty, no significant development based on the waters of the Indus and its tributaries, has taken place except for the construction of new irrigation canal (CRBC) from the Chashma Barrage, which on completion would irrigate an area of 0.23 Mha 90.568 MA).

For improving the control over the river flows and for power generation, a major dam on the Indus downstream from Tarbela, was planned in 1984. This Dam would have provided a storage 7.52 BCM (6.1 MAF) and added 3600 MW of hydro-power to the generating capacity. The construction of this dam however could not be taken up due to the controversies surrounding its adverse impacts.  

The surface irrigation system which is now all weir controlled, covers the world's largest contiguous irrigated area. It comprises of three storage reservoir (Tarbela, Mangla and Chashma with total original live capacity of 18.80 BCM (15.24 MAF), 16 barrages, 12 inter river link canals, 2 syphons, 43 main canals and 134, 000 watercourses or farm channels. The total designed diversion capacity of main canal is 7,249 cumecs (256,000 cusecs).

These features provide an opportunity for managing the surace supplies and canal system. 

The irrigation system dependent as it is on the variable flows of the Indus and its tributaries, commands a gross irrigable area of 16.85 Mha (41.46 MA) of which 14 Mha (34.59MA) is culturable command area (CCA) to which water is allocated. The perennial canal supply is available to 8.6 Mha (21.25 MA) while the remaining area is entitled to irrigation supplies only during  the Kharif season. The annual canal diversions which were 82.65 BCM (67 MAF) at the time of independence in 1947 have increase to 104.86 BCM (85 MAF) in 1967 and to 128.29 BCM (104 MAF) in 1975 after the commissioning of Mangla. At present 130.76 BCM (106 MAF) water is diverted for irrigation purposes.

WATER RESOURCES DEVELOPMENT AND MANAGEMENT

The Present Situation

The achievement of Water Vision is dictated by a consideration of the present position and how the present initiatives need to be channeled to achieve the desired objective. In respect of Water Resources Development and Management, the position has therefore been characterized, as a starting point, in the following section.

Available Water Resources

 

The water resources available to the country are the natural precipitation, the surface water and the groundwater. In the arid to the sub-tropical climate of the country, the natural precipitation is scanty. Over half the country receives less than 200 mm of annual rainfall, and rainfall in excess of 400 mm occurs only in about 20 percent of the northern areas. Apart from being scanty, the precipitation is distributed quite unevenly over the season and in a major part of the country this is concentrated in the 3 to 4 months of the summer monsoon. Despite its meager amount, rainfall is utilized for rain-fed agriculture and for meeting the drinking water needs of the people and livestock and contributes to the livelihood of a small but vulnerable portion of the population.

 

The source of surface water available to Pakistan are its rivers. Most of these rivers in the western half of the country, are ephemeral steams that remain dry for most of the year. It is the Indus river and its tributaries with perennial flows, that constitute the main source of water supply.

 

The Indus and it tributaries, have their sources in the Himalayan mountain and the Hindu Kush, with a total drainage area of 944,569 sq km, which extends beyond the country's territorial limits. The inflow to these rivers mainly derived from snow and glacier melt and rainfall in the catchment areas. The tributaries of the Indus, originating in India but flowing into Pakistan are the Jhelum, Chenab, Ravi and Sutlej (with a major tributary Beas). Originating in Afghanistan, the other major tributary is the Kabul River.

 

Under the Indus Waters Treaty 1960, the flows of the three Eastern Rivers, (Sutlej, Beas and Ravi) have been allocated to India, whereas with minor exceptions, Pakistan is entitled to all the water of the Western Rivers (Indus, Jhelum and Chenab). The average annual inflow of the Western Rivers at the rim stations (the most important gauging stations enter the Indus Plains is 172.70 BCM (140 MAF). This constitutes the main source of water supply for the country.

 

Although the surface flows of the Indus rivers and its tributaries available to Pakistan are quite significant these, are characterized by a great variation. Against the average annual inflow of 172.70 BCM (140 MCF), the long term historic data from 1922-23 to 1996-97 indicates a high of 230.42 BCM (186.79 MAF) or 30% below average in 1974-75. Apart from the large annual fluctuation, there is a large seasonal variation in these flows as well. The inflows during the six months of the summer cropping season of Kharif average 142.09 BCM (115.18 MAF) while the flows in remaining six months of the Rabi Season are 27.21 BCM (22.06 MAF) or only 16% of the average annual.

The quantity of surface waters in the Indus and its tributaries is excellent from all point of view. At the rim station the waters have total dissolved solids (TDS) ranging from 100 to 200 ppm and they do not represent any sodicity hazards. Although over the years drainage waters have been discharged into the rivers, the quality of the water even at the Kotri Barrage which is the last diversion point on the Indus, is characterized by a maximum value of TDS between the range of 150 and 350 ppm.

In addition to the surface water, groundwater is another important source of water supply. Investigations have established the existence of a vast aquifer with an areal extent of 194,000 sq. Km (74,904 sq mi) underlying the Indus Plains which has been recharged in the geological times from natural participation and river flows and more recently by the seepage from the canal system. Although the quality of the groundwater in the Indus Basin aquifer is highly variable, both a really and with depth, it is estimated that 67.85 BCM (55 MAF) of groundwater representing the safe yield, could be withdrawn annually for beneficial uses.

Outside the Indus Plains, the availability of groundwater has also been investigated through extensive sub-surface exploration and it has revealed the presence of useable groundwater in limited quantities in alluvial fans and valley aquifer.