The groundwater supplies in many regions around the world are being depleted to meet growing irrigation and other needs in the wake of diminishing surface water supplies e.g. USA and India (Rodel et al., 2009). The depletion of these groundwater supplies is expected to intensify as a result of climate change. These impacts are likely to be particularly severe in regions such as Bari Doab, where the groundwater is already being depleted at a very high rate. As the groundwater depletes the cost of pumping increases and risk of water quality deterioration also increases.
The research area lies in the Bari Doab between Rivers Ravi and Sutlej on Pakistani side of the border. The Bari Doab area is part of a vast stretch (about 40,000 km2) of alluvial deposits worked by the tributary rivers of the Indus. The parent material is of mixed calcareous alluvium derived from a variety of rocks during the Pleistocene period. The general slope of the area is mild towards the south-westerly direction, with average slopes ranging from 1 in 10,000 to 1 in 4,000. The predominantly agricultural land is at an elevation of 100m to 210m above mean sea level.
1.1 CLIMATE CHANGE
According to the Global Climate Change Risk Index (2014) Report, Pakistan is listed in the top ten countries which are the most vulnerable to climate change. The hottest day in the world, with temperature of 50.2 Celsius was recorded on 30th April, 2018 in the District Nawabshah, Sindh, Pakistan. Climate change can be natural or due to certain anthropogenic activities. One net impact is in the form of uncertainties to the water available for human activities, particularly for agriculture. Although Intergovernmental Panel on Climate Change (IPCC, 2007) has well-recognized climate change internationally and locally, but its impact on groundwater in Pakistan is found to be least researched rather not researched. Due to high temperatures, increase in evaporation and transpiration would increase water requirements for every sector. In contrary, the water availability is expected to decrease due to higher incidences of flooding and more prolonged and severe droughts. Consequently, these changes would influence the intensity and timing of precipitation. This will certainly impact surface storage and groundwater recharge. The ultimate impact would be groundwater depletion and reduction in the net water availability in contrary to increasing water requirements in every sector. Groundwater resources are related to climate change in any area through the direct and/or indirect interaction with surface water, although the response would be late.
There could be many impacts of climate change namely: change in monsoon pattern, increase in temperature and ET rates, increase in rainfall intensity, decrease in the number of rainy days, decrease in snow fall, increase in glacier melt and retreat, change in runoff pattern, decrease in groundwater recharge, increase in extreme events, sea level rise and deterioration in water quality increase in seawater intrusion. Increase in surface water flow is also possible due to an increase in rainfalls.
Reduced water availability in Indus Basin is expected due to the following:
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Decline in on-line water storage due to sedimentation in the reservoirs;
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Increasing in agriculture, domestic and industrial water demands;
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Required increases in environmental flows or in other words deteriorating water quality in rivers;
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Depleting groundwater resources leading to increasing river losses as is occurring now;
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Potential impact of climate change on water resources in the mountains also.
Concern regarding water availability has been growing in recent years regarding the potential impact of climate change on Pakistan’s already stressed water resources. Rising temperatures, increasing saltwater intrusion in coastal areas, floods (as observed in 2011 and 2022) or drought occurrence also, a growing threat of glacier lake outburst floods, more intense rainfall, and changes in monsoon and winter rainfall patterns are just some of the ways in which climate change is expected to affect Pakistan’s already stressed-water resources. These risks amplify an already problematic situation, given that Pakistan is among the most-water stressed countries in the world., i.e. per capita access to surface water (which is below 900 m3 per year) and groundwater sources are expected to continue to decline in the decades to come, driven largely by rapid population growth and urbanization in the country.
“The majority of Pakistan’s water is provided through the Indus River and its tributaries, which are fed primarily by snow and ice melt in the Hindu Kush-Karakoram-Himalaya Mountains. Any change in water flow in the Indus basin will have significant implications for food security in Pakistan given that 90 percent of total agricultural production occurs on arable lands supported by Indus Basin Irrigation System” (Qureshi, 2011). The Indus basin water flows also play an important role in meeting irrigation domestic and municipal water supply needs, as well as supporting the country’s energy mix, manufacturing and industrial processes. An important source of water for hill and mountain people are springs, providing supply for irrigation and household use. There is anecdotal evidence from across the HKH region that many of these spring sources are drying up. However, it is not clear whether this is due to climate change, increased use or environmental degradation (e.g. Tambe et al., 2011).
1.2 Spatial Climate Variability
The climate in Pakistan gradually increases in severity in the north-south direction, as shown in Fig. 1 for rainfall. But irrigation allowances are almost kept constant, particularly in Punjab. This is also the general flow direction of Indus Basin Irrigation System (IBIS) and canal commands. Thus, in general crop water demand increases and rainfall decreases in the head-tail end direction of the canal commands. Insufficient delivery of canal water in comparison to increasing cropping intensities and water demands has lead share of groundwater irrigation to be at par with canal supplies. This has given birth to groundwater mining problems and increasing irrigation costs in the tail-ends of the canal commands. More irrigation allocations towards the south depending on rainfall can ensure equity of irrigation costs and groundwater mining will be decreased.
1.3 Water Allowance of the Canals and actual Diversions
Most of the canals in Bari Doab are perennial; however some of the branches, particularly along Sutlej River are non-perennial. Perennial water allowance and 10 year average of actual irrigation water diverted to the canals in BARI DOAB are given and plotted in Fig. 2, but for some of the canals water allowance could not be found. However, it does not have any trend in d/s direction. Therefore, DTW is deep in d/s direction of BARI DOAB and high or shallow in u/s areas. Because recharge to groundwater due to rainfall and canal supplies is less in the d/s direction of the DOAB.
1.4 Situation in Bari Doab
The causes of groundwater depletion in Bari Doab most probablly are as under;
i. Stoppage of surface water flows in Ravi and Sutlej rivers.
ii. Enhanced groundwater pumping for agriculture and domestic usage.
iii. Population growth and limitation of groundwater resources.
In Bari Doab groundwater depletion is not due to over pumping in Indian Punjab because most of the recharge and discharge takes place in the vertical direction as shown by Basharat and Jawad (2020) that regional groundwater flow coming from India to Pakistan is still in its natural direction and very less as the groundwater movement is naturally very much slow.
The oldest possible situation is shown in Fig. 3 below, which shows that lower and central parts of Bari Doab area were having deep watertable as compared to upper areas This is due to spatial climate variability.
According to post monsoon 2014 situation, more than 59.1% area of Bari Doab was having depth to watertable (DTW) below 12 m, another 27.3% was having DTW between 6 to 12 m. Thus, only 13.59% area of Bari Doab had normal range of DTW (< 6m). Keeping in view the continuous depleting conditions in Bari Doab, drainage Section of IWASRI studied the feasibility of "Developing Sukh-Beas as Potential Recharge Site during Wet Years for Bari Doab". For recharging the Bari Doab aquifer, the proposal is to divert the flood water from Balloki-Sulemanki and Sidhnai-Mailsi-Bahawal Link canals into the Sukh-Beas channel, depending upon flood water availability in the river system and the carrying capacity of the channel itself (Basharat and basharat, 2019).
Figure 3: Groundwater depth in Bari Doab in 1977 (Ahmed, 1995).
Extensive groundwater development facilitated the increase in cropping intensity by addressing the ever increasing shortages in canal supplies due to sedimentation and also lowering the watertable, which also resulted in declining soil salinity. The BARI DOAB is therefore a conjunctive use farming system, however, without any regulation by the government for long-term aquifer management. A comprehensive tubewell census in LBDC Canal of BARI DOAB was carried out in 2005 by the Punjab Irrigation Department (PID) through its field staff under the guidance of NESPAK as consultants. The census provides the latest information on the numbers of tubewells, total operating hours and the total groundwater abstraction in both Rabi and Kharif on distributary commands basis. According to the survey, the reported number of tubewells were 48,102. The data was analyzed by NESPAK (2005) and the total groundwater abstraction had been estimated as 4674 MCM (3.78 MAF) by NESPAK, 2005. Figure 4 shows the turbine pump with PTO arrangement in Chak No.60/12L in LBDC of Bari Doab Region.
If the over-exploitation of water resources, particularly the groundwater, is not controlled by avoiding over pumpage and misuse of the same, the decreasing groundwater level will naturally aggravate the current conflict on water shortage amongst the provinces as well as among various users’ at all local levels. Also there is another danger of rapid declining groundwater levels which can cause salt-water intrusion due to up-coning from underlying saline aquifer or lateral movement from saline to fresh zones. The major issue facing Pakistan in the coming years can be lack of management regime for groundwater, leading to rapidly falling groundwater levels and pollution of both surface and groundwater. All these issues have impact on agricultural production, food security and the overall ability of the Nation to improve the economic performance of irrigated agriculture sector.
1.5 Proposed Re-allocation:
The scope for the re-allocation of irrigation duties in Punjab has been investigated by Basharat et. al. (2014). The challenge in Punjab at this stage is the overuse of groundwater. Basharat et. al., (2014) established that “there are only very few canals in Punjab that have excess supplies e.g. Muzaffargarh canal, but that in some of the larger canal irrigation water supplies can be better spread”. The big gains however are in Sindh, due to the high surface irrigation supplies in many of the canal commands, particularly Rice command. These high irrigation allocations – apart from giving rise to extensive waterlogging – have created disincentives to farmers to use groundwater, even in areas where groundwater is fresh. Lessons can be taken from the drought years 1999–2002 when ‘less was enough.
The irrigation duties should be set so to develop an optimum balance between surface water supplies and groundwater availability and usage and guidelines may be developed in support of this. This requires that surface water seepage is equivalent to groundwater use. It is postulated that more irrigation allocations towards south can ensure equity of irrigation costs and groundwater mining will be decreased.