PAKISTAN S GROUNDWATER RESERVOIR AND ITS SUSTAINABILITY

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1 PAKISTAN S GROUNDWATER RESERVOIR AND ITS SUSTAINABILITY Muhammad Amin Member Water, WAPDA, 705-WAPDA-House Lahore, Pakistan ABSTRACT Pakistan s major groundwater resource is in the irrigated areas of the Indus Basin, while the second source lies in the areas outside the Indus Basin. Canal irrigation was introduced in the Indus Basin about a century ago. Before the irrigation system the groundwater table was 100 feet below the ground surface in most of the Basin. With the introduction of the irrigation system, groundwater is now in a range of 5 to 30 feet below ground surface. The groundwater outside Indus Basin is in Balochistan province, where the recharge source is mainly precipitation. It is estimated that total annual groundwater potential of 66 MAF exists in the country. Groundwater development initially started in the public sector in 1960s. A total of public tubewells, having capacity of one to five cusecs, was installed. But most of these tubewells have now completed their physical life. However, public tubewells demonstrated an exiting example of groundwater development for the private farmers, and as a result, private tubewells have been installed with an average pumping capacity of 55 MAF. Groundwater development fulfilled the water requirements for the increasing population of the country and private farmers have invested about Rs. 24 billion rupees in groundwater development. Excessive use of groundwater has resulted in secondary salinization, especially in tail reaches of canals and continuous pumping has caused up-coning of deep saline water. Mining of groundwater has been observed in Balochistan province and the major part of the irrigated areas. There is need to manage the demand of water/groundwater and efficient utilization of water must be emphasized. Canal diversions should be increased to increase the recharge, while rainwater harvesting should be encouraged. An integrated approach to irrigation and drainage practices should be adopted and sustainable use of saline groundwater should be adopted wherever possible 1. INTRODUCTION Groundwater has emerged as an exceedingly important freshwater resource and its ever-increasing demand for agriculture, domestic and industrial uses ranks it as of strategic importance. Global estimates show that groundwater comprises one sixth of the total freshwater resources available in the world (Shah et.al 2000). In Pakistan the major groundwater resource is in the irrigated areas of the Indus Basin followed by the areas outside Indus Basin. Groundwater is a flexible resource which can be utilized whenever required, and which it has the added benefit of incurring no evaporation losses Before the canal irrigation system was introduced into the Indus Basin about a century ago, the groundwater table was 100 feet below the ground surface in the large part of the Basin. Today, the groundwater is found within the range of 5 to 30 feet below ground surface. Average annual canal diversions are 105 MAF, which is a major source of recharge in the Indus Basin. Outside the Indus Basin the groundwater is mainly in Balochistan Province where monsoon rainfall in the summer and western rains in the winter are the sources of groundwater recharge. The broad objectives of this paper are to: * Estimate the total groundwater potential in the Provinces * Look at the current groundwater exploitation * Determine the issues related to groundwater with regard to balanced use and management * Prepare recommendations for sustainable use of groundwater. 1

2 2. GROUNDWATER POTENTIAL IN PAKISTAN PROVINCES Indus Basin is spread over four provinces of Pakistan Punjab, Sindh, North West Frontier and Balochistan. The groundwater potential for each of these is discussed in the following sections. 2.1 Groundwater Potential in Punjab The main source of groundwater in the Punjab lies in the four hydrogeological zones, namely Potohar plateau & salt range, Piedmont areas, Alluvial plains and Cholistan desert. Indus River and its tributaries drain the province. In Punjab a lot of work has been carried out on seepage from the irrigation system and the resulting recharge to the groundwater (PPSGWP, 1998). The groundwater potential is based on rainfall recharge, groundwater recharge and recharge from irrigation system. The rainfall recharge of 9.90 MAF (15% from 380 mm/year) in different SCARP areas was worked out during the period (PPSGWP, 1998). The recharge from return flow, irrigation application, and sub-surface inflows was assessed 7.08 MAF (22.5% of 31.5 MAF). Canal seepage varies from 2 to 8 cfs/msf depending on the size of canal and drainage characteristics. A delivery of 24 large canals for the irrigation year was with an average of 54 MAF. The recharge from these canals was estimated MAF (40% of 54 MAF). The recharge from rivers was 3.5 MAF and return flows from domestic and industrial use were assessed as 0.57 MAF (22.5% of 2.52 MAF). The total available groundwater resource of the Punjab Province was estimated MAF. 2.2 Groundwater Potential in Sindh The most important feature is the Indus River, the sole source of surface water for the Province. The groundwater lies in the three hydrogeological zones namely Eastern (Thar) desert, Western mountain and Indus valleys. Useable groundwater in the Province is mainly found in the Indus Plain, which is recharged from the meandering river and from the irrigation network that has been developed in the area. The other source of recharge - rainfall, is quite scanty and its contribution to the resource is limited. Rainfall recharge was 1.96 MAF (2% of 265 mm per year) as worked out by ACE and Halcrow (2001). The recharge from return flows (22.5% of 38.2 MAF), irrigation returns (22.5% of 3.5 MAF) was assessed 8.58 MAF and 0.79 MAF respectively. In the Sindh, canal water losses have been taken as 15 % of the total average canal supply of 45 MAF for the period The recharges from these canals was estimated 6.76 MAF. The recharge from the rivers was assessed 0.3 MAF. The total available resource of the Sindh Province was assessed to be 18 MAF. 2.3 Groundwater Potential in North West Frontier The North West Frontier Province (NWFP) lies in the four broad geological units namely, metamorphic and igneous rocks of the northern mountains, Mesozoic rocks of the southeastern part, Tertiary rocks of the southeastern part and upper Tertiary. The main groundwater resources in the Province are the alluvial plains and many valleys, which are intermountain basins of tectonic origin. The rainfall recharge was estimated 0.7 MAF (7% of rainfall over a sub-catchment). The average flows for the period was 6.68 MAF (ACE and Halcrow, 2001). In this Province, recharges from the canal system were worked out 1.0 MAF (15% of 6.7 MAF). The groundwater recharges include returns from irrigation application, other return flows, sub-surface inflows and recharge from rivers. The recharge from the return irrigation flows was assessed 1 MAF (15% of 6.5 MAF) and other return flows (15% of 0.88 MAF) were worked out to be 0.13 MAF. The total groundwater resource of the NWFP was assessed as 3.11 MAF. 2.4 Groundwater Potential in Balochistan The regions of the Province, which are underlain by unconsolidated sediments formed by the deposition of mountainous outwash from the surrounding highlands, have been divided into 12 distinct Basins, flood plains and valleys fills. The Province lies in the five hydrological zones namely, Mountain ranges, Piedmont plains, Valley floor, plains and rolling sand plains. The groundwater, in substantial quantities, occurs in unconsolidated aquifers in almost all basins and sub-basins. The groundwater resources in six basins of the province namely Hamune, Lora, Kachhi Plain, Nari, Pishin and Zhob have been assessed. The effective rainfall coefficient of 20% to the annual rainfall for the mountain areas is used to estimate rainfall of 1.21 MAF. 3

3 In Balochistan canal supplies are small in total and restricted to the east of the Province, adjacent to Sindh Province. For the period the average canal flow was 1.94 MAF and recharge from these canals was assessed as 0.29 MAF (15% of 1.94 MAF). Most of irrigated area of this Province lies in a saline groundwater zone. Other components of groundwater recharge include return flows from irrigation application, other return flows, sub-surface inflows and recharge from rivers. The recharge from return flows of irrigation application was estimated 0.37 (22.5% of 1.62 MAF) and other return flow was 0.08 MAF (20% of 0.45 MAF). The total groundwater resource of Balochistan Province was assessed as 2.13 MAF (Table 2). 3 GROUNDWATER EXPLOITATION Due to existing highly permeable aquifers in most of the Indus Plain, it is possible to extract water easily and also to store large quantities of water (Hafiz, 2002). The use of tubewells for pumping groundwater for irrigation was started by the Irrigation Department Punjab, soon after independence. However, large-scale development of groundwater for irrigation, using tubewells technology, was started in 1958 by WAPDA through its salinity control and reclamation programme. As a result it was picked up by the private sector and large installations of private tubewells took place (see Table 1). The exploitation of groundwater in the four Provinces of Pakistan is complicated due to a number of natural and man-made factors. The numbers of tubewells have increased from 2700 in 1950 to over in the year The number of users are over 2.5 million farmers, who exploit groundwater through their own tubewells or hire from their neighbors. Patterns of use are highly variable and there is little understanding about any adverse interaction, which is likely to result due to the unsystematic and erratic nature of groundwater exploitation. In Punjab, the importance of groundwater can be ascertained from the fact that quantitatively, it is contributing over 50% of canal water supplies available at the farm-gate. Canal system provides about 55 MAF of water to Punjab each year. Of this amount approximately 40% recharge goes to the groundwater. This recharge and additional irrigation water is provided through groundwater extraction. Presently there are about private tubewells in the Province abstracting 30 MAF to cover an area of 51 MAC. Discharge of the private tubewells varies from less than 0.5 cusecs to more than 1.5 cusecs and operation factor ranges from about 3% to more than 30% with an average of 10.5%. Additional groundwater 4 MAF is extracted for SCARPs, industrial and domestic use. In Sindh Province presently, a small component of potential groundwater resources is being exploited by public and private tubewells. Total groundwater extraction is about 3.5 MAF, which includes pumping by private tubewells and 4100 SCARP tubewells. Groundwater of North West Frontier Province has been studied by M/S ACE & Halcrow (2001). Only a small percentage of the exploitable groundwater resource has so far been developed by dug-wells, tubewells or otherwise. In this Province, the existing groundwater abstraction through private and 491 public tubewells is 2 MAF per year. According to the study on private tubewells carried out by NESPAK (1991), the average capacity of these tubewells is 0.6 cusecs and their utilization varies from 24 to 27 percent. In the Balochistan Province present groundwater abstraction has been estimated 0.45 MAF by about private tubewells. The average capacity is 0.3 cusecs of private tubewells and 0.18 cusecs of pumped dug wells (ACE and Halcrow, 2001). 4

4 Table 1 Number of Private Tubewells in all Provinces Year Growth of Private Tubewells in Pakistan Punjab Sindh NWFP Balochistan Pakistan Number Annual Annual Number Number Annual Annual Number Number Annual Increase Increase Increase Increase Increase Groundwater Balance The overall water balance is actually comprised of certain recharge and discharge components. The details of these components with relevance to the groundwater system of the four Provinces are given below (Table 2). The difference between yearly recharge and discharge of an aquifer can be used as an initial guide to the sustainable development of the groundwater reservoir. But it is important to mention that it gives an overall picture of the Province. In certain areas of the province of Punjab and Balochistan mining of groundwater has aggravated the situation. The groundwater potential for the Sindh province is MAF; the additional sustainable groundwater deployment is worked out as MAF of groundwater (ACE and Halcrow, 2001), consisting of 3.52 MAF from the fresh groundwater zones and 6.80 MAF from saline groundwater zones. Approximately 65% of this development potential is located in the Rohri (FGW) and Nara (SGW) canal commands. 5

5 Table 2 Groundwater Balance for all four Provinces Parameters Punjab Sindh NWFP Recharge Component Rainfall Recharge Recharge from Canal System Return flow from irrigation Domestic & industrial return flows 0.57 Other return flows Recharge from Rivers Total Discharge Components Groundwater Abstraction (Private, STWs & PTWs) Groundwater Abstraction (domestic & 2.50 industrial) Non-beneficial ET losses Sub-surface Outflow/change in GW Baseflow to Rivers Total Source: ACE and Halcrow, Balochistan From the water balance in Table 2 it can be seen that the total groundwater resources for NWFP are 3.15 MAF. About 1.77 MAF of groundwater is being extracted. However, when the only available figures for other discharges from the Province are taken into account it would appear that the Province is in deficit. The ACE and Halcrow, (2001) report clearly stated that groundwater resources should be developed step-wise so that any unforeseen change in behavior of the aquifer could be taken into account in the next development stage. Table 2 reveals that groundwater resources for Balochistan are 2.13 MAF. About 0.45 of groundwater is being extracted. This indicates that a groundwater potential of 1.69 MAF is more available for the Province. However, 0.67 MAF of that potential resource is linked to the canal system in the east of the Province where the groundwater is generally saline. The remaining potential for the rest of the Province is 1.02 MAF. The sustainable groundwater development in the Province is 0.64 MAF (ACE and Halcrow, 2001), with 50% of this potential located in two basins of Porali and Hingol. The situation has worsened in a number of sub-basins since 1996 as the uncontrolled development of groundwater in the Province was allowed to continue. Some sub-basins within the Province (Quettea, Mastung, Mangochar and Pishin in the Pishin-Lora basin, Loralai, and Duki in the Nari basin) are rapidly approaching a catastrophic state in terms of groundwater resources and urgent action is needed to prevent. Thousands acres growing garden and vegetable crops in Loralai Basin have become barren due to the drying up of the aquifer. One of the reasons for higher exploitation of groundwater was the flat-rate cost of energy charged to the farmers. Therefore, it is necessary that energy charges should be proportional to the actual use of energy. 5. GROUNDWATER MANAGEMENT Because of the absence of groundwater management in the private sector, anyone can install a tubewell anywhere in his land and can extract whatever amount of water he wants any time without consideration of the detrimental effect of his action on the resource. If the pumping is equal to recharge rate for a sufficient period of time, the watertable depth will stabilize somewhere below the ground surface. In cases where the pumping of groundwater is in excess to the potential recharge rate, the mining of the aquifer will result in the accelerated depletion of the groundwater resource with an unsustainable lowering of the watertable. Also, the uneven groundwater development and pumping through private tubewells has started showing stress on the aquifer in the form of excessive draw-down and deterioration of groundwater quality. This requires serious attention and 6

6 the urgent adoption of measures for proper groundwater management. A groundwater regulatory framework should be introduced and implemented for the sustainability of groundwater use. Recharge of groundwater should be increased by increasing canal diversions, rainwater harvesting and check dams. In Pakistan, the irrigation system was designed for very low cropping intensities, but with population pressure, the design capacity is unable to cope with the actual cropping intensities. The difference between crop water requirements and canal supplies is met through exploitation of groundwater. The watertable data of the last 15 years indicates that in 43 canal commands the watertable is depleting. Continuous over-draft in excess of the average annual recharge has been resulting in the knocking out of shallow pumping wells. More pumping in relatively dry years, like nowadays, is causing excessive draw down in certain areas. As a result, at the present time, about 5% area of Punjab Province and 15% of Balochistan contains groundwater which is out of the reach of the poor farmers. This is likely to increase to 20% in Punjab and 30% in Balochistan in the next 25 years, with the present growth of groundwater withdrawals and unsystematic pumping of fresh groundwater due to abnormal lowering of the watertable and an increase in areas adjoining saline zones. In an effort to manage the increasing demand for water, low water delta crops should be preferred on high delta crops and more efficient irrigation methods should be used. In addition, there is a large area of the Indus Basin which has marginal and saline groundwater. This water can be used for saline agro-forestry and alternative agricultural crops. 6. CONCLUSIONS 1. Groundwater has become a major source of water supply in Pakistan 2. Excessive use of groundwater is causing secondary salinisation 3. The situation has worsened in a number of sub-basins in Balochistan Province due to groundwater mining 4. Continuous over-draft has resulted in excessive groundwater abstraction, so that 5% area of Punjab Province and 15% of Balochistan Province contain groundwater out of reach of poor farmers 5. Up-coning of deep saline water has started in some parts of Pakistan 6. There is a need to realistically estimate and manage the demand for water 7. The flat-rate energy charge has encouraged farmers to exploit more and more groundwater, which has resulted in an unsustainable situation. 7. RECOMMENDATIONS 1. A groundwater regulatory framework should be introduced and implemented for the sustainability of groundwater use 2. There is need to manage the demand of water 3. Low water delta crops should be preferred to high delta crops 4. Efficient irrigation methods should be used to irrigate crops 5. Recharge of groundwater should be increased by increasing canal diversions, rainwater harvesting and check dams 6. Saline water can be used for saline agro-forestry or for alternative agricultural crops 7. Energy charges should be proportional to the use of energy for tubewells 8. Research on groundwater recharge is urgently required. 8. REFERENCES ACE and Halcrow, (2001) Technical Report No.30, Exploitation and regulations of fresh groundwater, February Ahmad, Nazir, (1974) Water logging and salinity problems in Pakistan, Irrigation Drainage and Flood Control Research Council of Pakistan, Lahore. 7

7 Hafiz, A., (2002). Groundwater resources of Pakistan, International Waterlogging and Salinity Research Institute (IWASRI), WAPDA, Lahore. NDP, (200). Sector Planning Studies Interim Report, 1 Part B, National Drainage Program, Lahore. PEC, (1994) Proceedings of 65 th Annual session 1994, Paper No. 538, Pakistan Engineering Congress Lahore. PEC, (1994) Proceedings of 65 th Annual session 1994, Paper No. 543, Pakistan Engineering Congress Lahore. PEC, (1994) Proceedings of 65 th Annual session 1994, Paper No. 545, Pakistan Engineering Congress Lahore. PPSGWP, (1998) Annual Progress Report, Punjab Public Sector Ground Water Project, Lahore, WAPDA, (1981) Planning Division, Groundwater development and potential in canal commanded areas of the Indus Plain. 8