Resources, investigation and development
By Syed Fazl-e-Haider
Water is not only vital to the existence of human beings but for their socio-economic development as well. Groundwater is the primary source for drinking and irrigation. It is found under the crust of the earth and as a natural resource it provides security against drought. It is closely linked to surface water resources and the hydrological cycle.
The amount of groundwater in the world has been estimated at about 500,000 million acre feet (maf). According to experts, one fifth of this source lies in the active zone, within a depth of 2,500 feet of the surface. It is more than 30 times the water contained in all fresh water lakes and is more than 3,000 times the average volume of water flowing through rivers and streams.
The province of Balochistan is a water-starved and land-rich region in Pakistan. The groundwater tables are on decline due to mismanagement of water resources in the province. Besides streams, other sources are at the risk of over exploitation. The 9th five-year plan for Balochistan describes total water potential of the province as 12.2 million acre feet (MAF) originating from the following sources:
- Inland and coastal streams = 5 MAF (41%)
- Indus assured supplies = 3.9 MAF (32%)
- Flood supplies = 2.5 MAF (20%)
- Groundwater = 0.8 MAF (7%)
The most important use of water is for irrigation purposes in Balochistan. The extent of cropped areas with different types of irrigation is as follows:
Indus system: 285,300 hectares
Canal diversions: 60,160 hectares
Karez and springs: 44,700 hectares
Open wells: 17,430 hectares
Tube wells: 121,140 hectares
Total: 529,180 hectares
During the last five years, Balochistan government has accorded highest priority to water sector, for which major share of development finances had been reserved. In PSDP 2002-2003, 86 schemes were implemented with an allocation of Rs528 million. The work on 50 perennial irrigation schemes and 4 delay action dams have been completed which will bring an area of 45,000 acres of land under cultivation. During the FY 2003-04, an amount of Rs1601.884 million has been earmarked for implementation of 154 schemes (59 ongoing and 95 new) in water sector.
Balochistan is blessed with extensive groundwater resources. The hydrological map of Pakistan shows the groundwater regions, potential, quality and various hydrological parameters of the province. According to the map, out of total three main hydrologic units, two are located in Balochistan. These hydrologic units are as follows: Indus river basin, Kharan desert basin and Mekran coastal basin.
Balochistan can be divided into three hydrological regions: the Nari Basin, the Kharan closed Basin and the Mekran Coast. There are about 73 small or large rivers and streams constituting the three hydrological basins. Only about 30 per cent of this potential of rivers and streams are utilised through different schemes. A thorough and comprehensive investigation of all the basins in Balochistan is highly needed.
Groundwater occurs in the unconsolidated deposits in Balochistan. Layers of gravel with sand, slit and clay constitute the aquifers. Generally, groundwater occurs under water table conditions but water is also found under cartesian and semi-cartesian conditions at few places in Quetta, Kuchlak, Mastung, Panjgur and Kachhi plain.
Gravel aquifers occur in the hydrologic basin of mountainous areas of the province. Fissured aquifers exist in hard rocks, which permit storage and movement of water. These aquifers are widely spread in Balochistan. The groundwater in fissured aquifers in carbonate rocks of Quetta and Kalat has locally been developed through tubewells. The sedimentary rocks in northern areas of the province bear water due to fissures or faults exposed to the surface.
The province enjoys diversity in topography and geology and therefore it is rich in groundwater resources offering best projects for developing groundwater. Expansion of agriculture and other economic activities in the province will require tapping of groundwater potential of the province.
The recent estimates of availability and use of groundwater indicates that this resource has been heavily overexploited affecting both quality and quantity of groundwater. Therefore, the needed is to initiate groundwater investigations on scientific lines in the province.
In the year 2000, an integrated geophysical survey was conducted in Quetta valley and surroundings for the assessment of hard rock aquifers. The said survey was completed by the year 2003 and investigations indicated that Chiltan limestone was a primary hard rock groundwater resource for Quetta valley and surroundings. The tested discharge from the bore holes drilled, have quantified more than 20 mgd of hard rock groundwater resource which could be tapped for augmenting the water supply and ameliorating the pressing demand for more water in different sectors.
It is however contended that vast areas under Barani land, desert areas and several hard rocks in Balochistan are yet to be investigated. A study by Geological Survey of Pakistan (GSP) in 1970 had recommended testing of hard rocks in the basin as a potential source of good aquifers, which was still untapped. This negligence of the ruling elite in the past immensely afflicted the people and was still causing sufferings to the people because of drought effects in the province.
The WAPDA hydrogeology project has estimated the groundwater potential in terms of flow at 1,116 cusecs (cubic feet per second), while 687 cusecs were already utilised, which leaves 429 cusecs for future development. Another study indicates the availability of 270 cusecs for further development. Both estimates are based on only a partial survey of the basins.
Water table on decline
The water table has been declining continuously in the province. Studies suggest that the deficit in Quetta sub-basin is about 21,000 AF per year and that the aquifer storage will be exhausted in 20 years. The groundwater is depleting every year, in some places even with one meter per year especially in the Pishin-Lora Basin. Zhob and Nari river basins are not available for further groundwater development. The lowering of the water table is a matter of great concern that can have negative effects on all spheres of life.
Karezes is a traditional system of tapping groundwater for irrigation and has been practiced in Balochistan for centuries. The system is unique, as it needs no energy to pump groundwater being flowing under gravity. Over the years, however, the system has come under great stress, because of the commissioning of a large number of deep tubewells in the valleys. These tubewells have been instrumental in causing ground water mining and lowering of the water table.
The government of Balochistan has imposed a strict ban on the installation of tubewells in certain areas such as Quetta, Mastung, Mangochar, and Pishin. A no objection certificate is required prior to the installation of a tubewell. The three principal statutes dealing with different aspects of water use include the following: Balochistan Groundwater Rights Administration Ordinance, 1978, Groundwater Ordinance XX of 1980 and the Balochistan Water Users Association Ordinance of 1981. The hydrologic factors and human-made structures (dams, canals etc) are responsible for the accumulation of groundwater in plains, valleys and hard rock areas. These man-made structures have obstructed the natural flow of water, which ultimately caused waterlogging and salinity problems in different areas of the country.
Some suggestions worth considering as as under:
(a) A survey of the entire area of Balochistan should be conducted for assessment of the available groundwater resources and their development.
(b) In valleys where mining takes place in Balochistan, recharge arrangements must be carried out. The check dams or delay action dams have a salutary effect on the groundwater resources. Technically, the construction of delay action dams at appropriate points are considered the possible remedy for keeping Karezat (underground water channels) alive. Experts argue that delay action dams ensure recharging of groundwater table at different points and impede the course of drying up of Karezat. Balochistan provides highly suitable and favourable conditions and environment for building delay action dams.
(c) There is a need to explore the idea of building groundwater dams, which store water underground, rather than on the surface. Water that is stored in the soil does not evaporate like ponds and streams. It is clean, healthy and free from parasites. The key is to find ways to capture wet season rainfall underground. There are many ways to do this, both traditional and modern, but whatever method is used, the principle is the same: slow down the flow of water as it runs downhill.
(d) The watershed degradation is a problem in Balochistan. It causes decline in groundwater table. The watershed management is aimed at recharging groundwater aquifer, rehabilitating rangelands, controlling flash floods and enhancing fuel wood production in the target area.
(e) There is a needed to carry out a thorough and comprehensive investigation of all the basins in Balochistan. Such investigation obviously requires resources and expertise, which should be arranged and made available by the federal government.