Groundwater-food security nexus under changing climate-historical prospective of Indus basin irrigation system in Pakistan

Irrigated agriculture plays a vital role in the economy of Pakistan by contributing about 90% of food production, 22% of GDP, employing about 45% of the overall labor force, and generating over 60% of foreign exchange. The role of water resources has become significant which underpins the food security in the country. Indus Basin Irrigation System (IBIS) is the lifeline for the economy of Pakistan and is the major pillar of food security. IBIS is one of the largest irrigation networks in the world and is confronted with multidimensional challenges out of which climate changes have attained paramount importance. The irrigation system was designed on a 67% irrigation system during the 19th century while the current cropping intensity has crossed the limits of 150-160% or even more. Continuous increase in population and consequently more food demands have shifted the pressure on the aquifer underlying the Indus Basin. India, USA & China, and Pakistan has become the 4th largest user of groundwater where about 40% of irrigated food production is dependent on groundwater. In Punjab province, about 1.2 million tubewells are extracting about 40-45 MAF of groundwater annually. Consequently, groundwater management has confronted a multitude of tiny users in Pakistan. Climatic changes have made the availability and reliability of surface water a question mark. Resultantly pressure on groundwater is increasing and water levels are dropping abruptly taking this resource beyond the bounds of rural poor farmers. The intrusion of saline water into the fresh aquifer, secondary salinity, and seawater intrusion are the major threats to groundwater quality.  About 3000 piezometers have been installed to monitor groundwater behavior (levels and quality) in the Punjab province. A research study carried out in Lower Bari Doab Canal (LBDC) has indicated that by falling of water table from 40 to 70 ft. the cost of pumping per acre-feet of groundwater has increased by 125%.  Similarly, it has been observed that in many urban areas groundwater is depleting at an annual alarming rate of 2.54 ft., (Lahore city) and the water table in sweet water zones in rural areas (Vehari District) has gone beyond 70-90 ft. Human activities like increasing cropping intensities, unplanned over pumpage, lack of awareness/capacity, use of chemicals in agriculture/food production, industrialization, urbanization, solid waste landfills, domestic effluents, lack of legal and regulatory framework, etc. are the major threats to sustainable use of groundwater for food security. Climatic changes are posing severe adverse impacts on the sustainable use of groundwater which is putting food security under threat. Global warming, rising sea levels, glacier melting, unprecedented rainfall, prolonged droughts, and floods are the consequences of changing climate which are affecting directly or indirectly the groundwater resources in the aquifer underlying the Indus Basin

RAINFALL ANALYSIS FOR WATER RESOURCES APPLICATIONS: A CASE STUDY AT BAHAWALNAGAR, PAKISTAN

This study was aimed to demonstrate screening of the rainfall data for water resources applications, Bahawalnagar station in Pakistan was selected as the case study. The ultimate goal of this study was to test the rainfall record for stability, trends, consistency and homogeneity for its further utilization. The rainfall data were collected from the Meteorological Department of Pakistan for a period of 31 years ( 1962 to 1992) on 3-hourly basis.The missing for four years ( 1965, 1968, 1975 and 1978) were estimated by normal ratio method, taking into account the three surrounding stations namely Multan, Bahawalpur and Khanpur. Annual maximum moving rainfall totals for 3, 6, 12, 24, 48 and 96 hours were calculated to construct six series of rainfall data. Various standard procedures were applied to test the consistency, homogeneity and stability of rainfall series. F and t tests were employed to test the stability of variances and means of rainfall series. The results revealed that data were stable, trendless and homogenous. The results from double mass analysis indicated that the rainfall records at Bahawalnagar and three surrounding stations were consistent relative to each other. The data were thus declared objectionless for further use for frequency analysis

Physicochemical Investigation of Rainfall for Managed Aquifer Recharge in Punjab (Pakistan)

In a water-scarce country such as Pakistan, rainfall is the third-largest source of freshwater. In most of the urban cities of the country, rainwater is mixed with sewerage and is rendered useless for managed aquifer recharge purposes. Therefore, this study investigates the rainfall potential for managed aquifer recharge in Lahore (Pakistan). The present research was designed and conducted by the Irrigation Research Institute (IRI). Three different sites were selected for rainwater sample collection across the study area (Lahore), ranging from urban to rural areas. The rainwater samples were collected and divided into three categories (direct capture, rooftop runoff, street runoff). For longer rainfall events, the effect of time on the quality of the collected rainwater samples was also studied. Spatiotemporal trends of turbidity, pH, electrical conductivity, total dissolved solids, carbonates, bicarbonates, chloride, calcium, magnesium, and hardness in the collected rainwater samples were investigated. In terms of TDS, results indicated that directly captured rainwater is most suitable for managed aquifer recharge (TDS < 50 ppm), followed by rooftop runoff (TDS < 100 ppm). In addition, the quality of rainwater samples collected at the rural site was comparatively better. Moreover, the quality of rainwater samples improved after the initial ten minutes. All in all, this study concludes that direct capture of rainwater is the most suitable option for managed aquifer recharge

Physicochemical Investigation of Rainfall for Managed Aquifer Recharge in Punjab (Pakistan)

Gefördert durch den Publikationsfonds der Universität Kasse

Evaluation of hydraulic efficiency of lined irrigation channels – A case study from Punjab, Pakistan

Indus Basin Irrigation System (IBIS) in Pakistan is the backbone of agriculture in the country. The IBIS provides irrigation support to agricultural lands across the country; however, hydraulic efficiency of the water conveyance system is impacted due to seepage losses. The lining of irrigation channels is considered a potential solution for improving hydraulic efficiency. Therefore, this study explores the impact of canal lining on the hydraulic efficiency of the canals in the Punjab province of Pakistan. Overall, 14 channels/distributaries/minors (total length 226 km) were monitored in terms of hydraulic performance in different irrigation zones. Hydraulic, geometrical, and socioeconomic parameters of channel/distributaries/minors including roughness coefficient, sediments, flow velocity, wetted parameter, breaches, theft cases, bed, side slope, water surface profile, hydraulic radius, crop yield, and vegetation growth area have been experimentally observed. Obtained results have been compared with the design and pre-lining data. Ten seepage tests using the inflow -outflow method and eight seepage tests using the ponding method were conducted to estimate seepage losses. Results indicate that almost all the parameters varied from the design values. A detailed comparison of the socioeconomic parameters has been carried out. Results from seepage tests show an approximately 78% reduction in losses. HIGHLIGHTS Canal lining has reduced seepage losses by ∼78%.; Built cross-sections are ∼5% bigger than design cross-sections.; Concrete lining (1:2:4 P.C.C.) is more suitable for future canal lining.; Froma socioeconomic view, canal lining improved equity and reliability of water distribution.; The useful physical life of 1:2:4 P.C.C. lining is 30–50 years, brick lined ∼20–25 years, and protected geosynthetics more than 50 years.