OR/14/068 Introduction

Lapworth, D J, Gopal, K, Rao, M S, and MacDonald, A M. 2014. Intensive groundwater exploitation in the Punjab — an evaluation of resource and quality trends. British Geological Survey Internal Report, OR/14/068.

Groundwater is a critical resource for millions of people in the Punjab who rely on it for drinking water, agriculture and industry. Overall, the Punjab region is highly dependent on groundwater (Garduno et al., 2011; Wada et al., 2010 ; 2012).

The mid plains region of NW India is one key area for food production where groundwater levels have been reportedly dropping over a sustained period of time due to intense abstraction (Wada et al., 2012). While groundwater levels are falling in some parts of Punjab, evidence from modelling work suggesting that groundwater recharge in this region is actually increasing (Döll, 2009) and may continue to do so for some time, with pressures from intensive pumping the two processes are not mutually exclusive. Modelling studies undertaken in India suggest that pumping may actually induce post monsoon recharge in some parts of the IGB (e.g. Chaturvedi and Srivastava, 1979). Understanding the connectivity of the shallow and deep aquifers is important for assessing both the vulnerability of the deep aquifers to the migration of contamination to depth and understanding sources of recharge in the deeper aquifers. Using environmental tracers, such as chlorofluorocarbons (CFCs) and isotopes, is one key way to explore connectivity and anisotropy in this aquifer system.

This report outlines preliminary findings from a case study focussed on understanding the response of groundwater resources to sustained abstraction for irrigation in Punjab State. The aim of the case study is to examine the response of groundwater in a representative Doab to current pressures from abstraction and pollution and forecast likely future trajectories. Specific objectives were:

• To collate historical water level responses to abstraction across the catchment
• To collate new evidence on recharge processes, groundwater quality, groundwater residence times, and connectivity of the layered aquifer systems and surface water by repeated sampling of shallow and deep piezometers using a suite of environmental tracers
• To obtain new high frequency data on water level variations in shallow and deep piezometers for one hydrological year

Background — punjab and the green revolution

Punjab means the land of five Rivers: the River Jhelum, Chenab, Ravi, Satluj and Beas, and all are tributaries of the Indus River. The Indian part of Punjab is divided into four geographic regions: Malwa (region south of river Satluj), Bist Doab (region between the rivers Satluj and Beas), Majha (region west of river Beas) and Powadh (region in Rupnagar and Ambala district) that falls between the Rivers Satluj and Ghaggar.

Punjab state is one of the most productive agricultural regions in India. This is a semi-arid region with annual average precipitation of ca.700 mm. The agricultural activity of the state is reliant on a dense network of canals, with a total length of 14 500 km that distributes water from the Rivers Satluj, Ravi and Beas as well as the extensive use of groundwater extraction for irrigation (approx. 33 BCM per year (Punjab Remote Sensing Centre, 2008) through millions of its state and private owned pumps. From the 1960s an era of sharp agricultural growth in Punjab was sustained partly through intensive irrigation. The state has become synonymous with the ‘Green [agricultural] Revolution’ which was sustained in part though the intensive growth in groundwater irrigation. This boom in the agricultural sector earned Punjab the accolade of the ‘bread basket of India’ due to its spectacular growth in wheat and rice production. Punjab is the highest per capita electricity consuming state in the country. The agricultural dominance of the state can be seen from the fact that the state produces 19.5% of India’s wheat, 11% of India’s rice and 10.26% of India’s cotton. In 2013 the state’s NPK fertilizer consumption was 470 kg per hectare of sown area compared to 54 kg nationally (Statistical Abstract, Punjab, 2013; Indian Department of Fertilizers 2014).

Table 1 summarises the changes in cropping patterns for Punjab between the 1970 and 2012. This shows that agricultural output in the state has grown significantly since the adoption of modern techniques in the late 1960s (Sidhu, 2005). Important crops for the state include rice, sugarcane, fruits and vegetables. Industries in the state include the manufacture of scientific instruments, electrical goods, financial services, machine tools, textiles, sewing machines, sports goods, starch, tourism, fertilizers, bicycle, garments and the processing of pine oil and sugar. Most of the Punjab is an alluvial plain, bounded by mountains to the north.

Table 1    Cropping patterns in Punjab (Area in ‘000 ha)

Crop	1970–71	1980–81	1990–91	1999–2000	2000–01	2011–2012
Rice	390 (6.9)	1183 (17.5)	2015 (26.9)	2604 (33.2)	2612 (32.9)	2826(35.8)
Maize	555 (9.77)	304 (4.50)	183 (2.44)	163 (2.08)	164 (2.07)	133 (1.69)
Bajra & Jowar	212 (3.73)	70 (1.03)	12 (0.16)	5 (0.06)	6 (0.08)	2.5 (0.03)
Groundnut	174 (3.06)	83 (7.23)	11 (0.15)	5 (0.06)	4 (0.05)	2.0
Cotton (American)	212 (3.73)	502 (7.42)	637 (8.49)	381 (4.86)	358 (4.51)	482.8 (6.25)
Sesame	15 (0.26)	17 (0.25)	18 (0.24)	145 (1.85)	19 (0.24)	5
Sugarcane	128 (2.25)	71 (1.05)	101 (1.35)	108 (1.38)	121 (1.52)	70 (0.89)
Kharif Pulses	33 (0.58)	58 (<0.86)	73 (0.97)	51 (0.65)	42 (0.53)	-
Wheat	2299 (40)	2812 (41)	3273 (43)	3388 (43)	3408 (42)	3510 (44)
Barley	57 (1)	65 (0.96)	37 (0.49)	51 (0.65)	32 (0.40)	11.7 (0.15)
Gram	358 (6.3)	258 (3.81)	60 (0.8)	6 (0.08)	8 (0.1)	2.2 (0.03)
Rapeseed & Mustard	103 (1.81)	136 (2.01)	69 (0.92)	56 (0.71)	55 (0.69)	-
Potato	17 (0.30)	40 (0.59)	23 (0.31)	76.0–(1)	64 (0.81)	64 (0.81)
Other Vegetable	23 (0.41)	24 (0.36)	31 (0.41)	47 (0.6)	46 (0.58)	-
Fruits	50 (0.88)	29 (0.43)	69 (0.92)	30 (0.38)	34 (0.43)	71.5
Net Sown Area	4053	4191	4218	4243	4264	4158
Total Cropped Area	5678	6763	7502	7847	7935	7882
Cropping Intensity	140	161	178	185	186	190

Source: Statistical Abstract of Punjab, 1971, 1981, 2000, 2001, 2010. Area for each crop is shown in units of ‘000 ha with figures in parentheses indicate area
under crops as percentage share to total cropped area. Cropping intensity is total cropped areas (single+double+triple)/net cropped area * 100.

Groundwater and irrigation in the punjab

The network of canals, some of which are more than 150 years old, have steadily reduced in their carrying capacity due to siltation and leakage and decreased the availability of surface water across the region. The net-area irrigated by canals has decreased from 55% in 1960–61 to 29% in 2006–07. The canal irrigation system irrigated about 1.3 million hectare of land in 1970–71, while only one million hectare was irrigated during 1999–2000. In contrast, tube well irrigation, particularly in the central and northern region of Punjab, has increased from 55% in 1970 to 75% in 200–02 (Punjab Remote Sensing Centre, 2008) (Figure 1). In the state of Punjab the level of groundwater use is estimated to exceed replenishable groundwater resources by a factor of 1.4, the highest level of overuse of any state in India (Gandhi and Namboodiri 2002). Today there are an estimated 1.1 million tube wells in the state abstracting water for agricultural irrigation and another estimated 150 thousand in urban and semi urban areas to provide water for domestic and industrial purposes.

Figure 1 Comparison of net irrigated area (‘000 ha) by different sources in Punjab (Source: Statistical Abstract of Punjab, 2013).

Long-term downward trends in parts of the mid Plains Aquifer in Punjab (NW India), in the headwaters of the Indus, suggest that the current pumping regime is not sustainable, and will likely impact the poorest parts of the community which cannot afford to deepen boreholes (Chawla et al., 2010; Fishman et al., 2011). The intensive farming carried out in this region largely relies on pumping from the shallow aquifer (0–50 m) and uses large quantities of fertilisers and chemicals to control pests and sustain yields (Chaudhary et al., 2000; Kuldip-singh et al., 2013). In responds to the groundwater security issues in Punjab a number of initiatives are being implemented by the state government for improving water use efficiency, these include:

• Propagation of irrigation water saving techniques, for example laser grading of fields, zero tillage and directly seeded rice
• Rainwater harvesting and recharge structures are being constructed in the sub-mountainous region
• A subsidy of up to 85% on micro-irrigation, a 50% subsidy on underground pipeline systems to individual farmers, 90% subsidy for the community underground pipeline projects
• Watershed management projects are being implemented in 26 locations

The rapid expansion of urban centres in NW India has also contributed to the anthropogenic contaminant loading in the shallow aquifers of the Plains (Purushothaman et al., 2012; Singh, 1994). As such, the shallow aquifers in this region are polluted, both microbiologically and chemically, and are not reliable sources of drinking water. To mitigate this problem there have been large programmes across groundwater dependant states such as Punjab to install deeper boreholes (ca.150 m) to supply groundwater for drinking water in urban and peri-urban settings which requires minimal treatment. How sustainable this is in the long-term depends on the nature and degree of contamination in the shallow subsurface, as well as the vertical variation in the hydraulic properties and geochemical conditions within the layered sedimentary aquifer system. There is currently a limited understanding of the degree of confinement in the deeper aquifers and their sources of recharge. A better understanding of the vertical age profiles and water quality variations within the layered sedimentary aquifer is needed to inform and support a thorough assessment of the vulnerability of the deeper aquifers to i) the downward migration of contaminants from shallow sources and ii) the mobilisation of natural sources of contamination at depth due to changing redox conditions.