Prof Dr Muhammad Shafqat Ejaz Back Ground Groundwater (GW) as a - PowerPoint PPT Presentation

13 th Symposium: “Water Stress” April 27, 2019 11 35 - 12 05 hours Prof Dr Muhammad Shafqat Ejaz

 Back Ground › Groundwater (GW) as a Major Resource › Issues and Threats to the GW Resource  Conventional GW Mapping Strategies  Latest GW Mapping Strategies

 Groundwater forms an integral part of the water cycle.  Groundwater supplies 1/2 of all drinking water in the world (UNESCO-WWAP, 2009)  Groundwater Irrigation and conjunctive use of groundwater is under practice for agriculture production system for centuries.  Groundwater supplies 43% of the global consumptive use in irrigation (Siebert et al., 2010

World’s aggregated groundwater abstraction is 1,000 km 3 per year 67% of all groundwater is used  Industrial for irrigation (food production) 11% 22% of all groundwater is used Domestic  22% for domestic purposes (drinking Food Production water and sanitation) 67% 11% of all groundwater is used  for industry (Ref: https://www.un- igrac.org/what-groundwater

 Surface water resources are particularly vulnerable to pollution, and are often limited in magnitude, particularly in arid regions.  Groundwater resources are hidden and often poorly understood, but they are widespread, relatively easy to protect from contamination, and their development potential is great.  Shallow groundwater in particular is relatively easy to access, and suitable for small scale development for domestic, livestock, and irrigation use in less developed countries.  Groundwater resources are coming under increasing threats from growing demands, wasteful use, and contamination.

 Increasing water demands in urban and rural areas put increasing pressures on the use of groundwater.  Increasing contamination of the resource as a result of urban, industrial and agricultural expansion, make it essential to properly manage these resources to guarantee their long term sustainability and to preserve water quality.  Soil salinization is often associated with irrigation practices but is also driven by natural groundwater processes.  Integrated catchment management including groundwater is the key to solving the continuously expanding environmental problems of salinity, water logging and land degradation as well as the preservation of ecosystems.

Potential threats to GW Resource Many cities have experienced rapid growth of urban & industrial waste disposal to the groundwater

Early warning of potential threats to Aquifer + GW supply quality .....thus, necessitating a focused GW quality management monitoring, using sampling piezometers.

 Existing Groundwater usage/level survey – Monitoring  Geological and topographical maps  Geophysical Methods (Depth to ground water and its quality)  Borehole Investigations (Litho logs, Fence diagram, strata characterization, etc)  Production bore Investigations  Aquifer properties  Well Capacity Analysis  Observation Well/Piezometer Network (SCARPs Monitoring Organization- SMO)  DTW Mapping (Pre- and Post-Monsoon)  Water Quality Mapping

 Hydrogeologic investigations carried out in 1950s and 1960s, in the Indus Plain (Ref: Unites States Department of the Interior, 1967;WAPDA, 1980a; WAPDA, 1980b)  3322 test holes were drilled,  1587 tube wells were installed and  856 pumping test were carried out  Characterization › The Indus Plain is underlain by deep, mostly, over 300m (1000 feet), deposits of unconsolidated and highly permeable alluvium deposited by river Indus and its tributaries in a subsiding tectonic depression lying between the Himalayas and contiguous mountain ranges and Plateau › The bulk of the alluvium consists primarily of fine to medium sand, silt and clay. Fine grained deposits of low permeability (silts and clays) generally are discontinuous so that sands, making up 65 to 75 percent of the alluvium in most areas serve as a unified and highly transmissive aquifer.

 Aquifer Parameters (on average) › Average specific yield 19 percent for Punjab aquifers and 13 percent for Sindh aquifers. › Lateral hydraulic conductivity  84 m/day (0.0032 ft/second) in Punjab and 29 m/day (0.0011 ft/second) in Sindh. › Anisotropy Ratio  55:1 in the Punjab and 30:1 in Sindh

Oct 2010 Oct 2002

 Lahore - In 2010, there were about 467 tubewells operated by WASA. total groundwater withdrawal was of the order of 1300 cfs. With this groundwater withdrawal, annually pumped groundwater volume was 1161 MCM (0.94 MAF)  Groundwater in Lahore varies from 20 to 45 m below NSL

 Increasing demands of ground-water resources and its vulnerability to contamination are creating a need for improved scientific information and analysis techniques to better understand and map ground-water systems.  Mathematical GW Hydrodynamic Models help in understanding and map GW Resources: › Simulation Models › Optimization Models

 Since the 1960s, numerical simulation models have been important tools for the assessment of ground-water flow systems and ground-water development strategies  These models are used to test specific water-resource management plans, or, in a trial-and-error approach, to select a single plan from a few alternative plans that best o meets management goals and constraints.  Because of the complex nature of ground-water systems, large number of engineering, legal, and economic factors that often affect ground-water development and management, the process of selecting a best operating procedure or policy can be extremely difficult.

Observed Calibrated 140000 140000 130000 130000 120000 120000 110000 110000 100000 100000 90000 90000 80000 80000 70000 70000 60000 60000 50000 50000 40000 40000 30000 30000 20000 20000 10000 10000 0 0

Future GW Mapping Extent of Areas with Water Table in LBOD-Nawabshah within 1.5m Depth in 2020 1. April 1993-Before Functioning 2 1 of Tubewells in LBOD- Nawabshah Component Project 2. April 1998-Current Management Practices 3. April 2003-Continuation of Existing Practices 4 3 5 4. April 2003-Tubewells Operation at Installed Capacity 5. April 2003-Tubewell Operation at Installed Capacity in Critical Areas only

1989   Recharge: 46.4 MCM/yr  Discharge: 54.6 MCM/yr  Net withdrawal: 8.2 MCM/yr 2004   Recharge: 43.2 MCM/yr  Discharge: 62.1 MCM/yr  Net withdrawal: 18.9 MCM/yr

 In some cases, however, the model may determine that none of the possible strategies are able to meet the specific set of management goals and constraints.  Such outcomes, while often not desirable, can be useful for identifying the hydrologic, hydro-geologic, and management variables that limit water-resource development and management options.

 Mathematical programming techniques are among the earliest and most commonly used for optimal groundwater management.  In common, they share formulations involving a goal that attempts to › minimize or maximize a single-objective or multi-objective function, subject to › a series of constraints on variables describing the state of the system, such as  hydraulic heads  concentrations  limits on dependent and decision variables, such as pumping and recharge rates.

 In the simulation-optimization approach, the modeler specifies the desired attributes of the hydrologic and water-resource management systems (such as minimum stream flow requirements or maximum allowed ground-water level declines) and the model determines, from a set of several possible strategies, a single management strategy that best meets the desired attributes.  The use of combined simulation-optimization models greatly enhances the utility of simulation models alone by directly incorporating management goals and constraints into the modeling Process

 GRACE - Gravity Recovery and Climate Experiment To monitor the variations in groundwater storage, Pakistan Council of Research in Water Resources (PCRWR) used NASA’s Satellite Mission data in Punjab  GRACE is made up of a pair of identical satellites that, together, can map tiny variations in Earth's gravity, allowing scientists to track the motions of mass around and http://www.pcrwr.gov.pk/hq.php?view_st within the globe.

 Sur ’ ah Mulk ُكيِتْأَي نَمَف اًرْوَغ ْمُكُؤاَم َحَبْصَأ ْنِإ ْمُتْيَأَرَأ ْلُق نيِِعم ٍاَمِِ م – Say, "Have you considered: if your water was to become sunken [into the earth], then who could bring you flowing water “