Large Dia Well Tests

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  • Thank you. Excellent.
    I am working in Kerala Rural Water supply and Sanitation Project, as Hydrogeologist. For community water supply develop large diameter dug wells, as well as bore wells in a few Panchayaths.We have to know the safe yields, especially in peak summer when water columns are 1m in many wells, and especially in silty valley fills ( and also in hard rock area in mountainous regions) well yields in summer are low, and we want to know the sustainability and safe yields, so that we can make sure if a well would meet the requirement of say, 40 HHs, and also to know the pumping rate and schedule. Many of this wells aare in unconfined aquifers with vertical anisotropy, and many are partially penetrating(eg, clay/lateritr bottomed), and some fully penetrating (hard rock bottom). In valleys and sandy/loamy areas wells have RCC stein, and in laterites and rocky area , laterite brick stein or RR stein. Which aquifer test method I can use to estimate safe yield and full recovery time? Can you please also inform me on free software to analyse pumping test data? Thank you
    -SHAJAN JACOB, contactshajanjacob@gmail.com
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Large Dia Well Tests

  1. 1. P T A – LARGE DIA By A.V.S.S.Anand Scientist Central Ground Water Board Government Of India (avssanand@yahoo.com) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  2. 2. P T A – LARGE DIA <ul><li>Types of Formations </li></ul><ul><li>Aquifer </li></ul><ul><li>Aquiclude </li></ul><ul><li>Aquitard </li></ul><ul><li>Aquifuge </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  3. 3. P T A – LARGE DIA <ul><li>Types Of Formations </li></ul><ul><li>Homogeneous </li></ul><ul><li>Heterogeneous </li></ul><ul><li>Isotropic </li></ul><ul><li>Anisotropic </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  4. 4. P T A – LARGE DIA Types Of Formations ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  5. 5. P T A – LARGE DIA <ul><li>State Of Flow </li></ul><ul><li>Steady State </li></ul><ul><li>Unsteady State </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  6. 6. P T A – LARGE DIA <ul><li>Direction Of Flow </li></ul><ul><li>Fully Penetrated </li></ul><ul><li>Partially Penetrated </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  7. 7. P T A – LARGE DIA <ul><li>Types Of Aquifers </li></ul><ul><li>Confined </li></ul><ul><li>Semi Confined </li></ul><ul><li>Unconfined </li></ul><ul><li>Semi Unconfined </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  8. 8. P T A – LARGE DIA <ul><li>For Optimum Utilization Of Ground Water Resources </li></ul><ul><li>Understand fully The aquifer </li></ul><ul><li>If Large diameter wells are used </li></ul><ul><ul><li>No Additional Cost Of Construction etc </li></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  9. 9. P T A – LARGE DIA <ul><li>It Is not Simple To Analyse This data Because </li></ul><ul><li>Effect Of Storage </li></ul><ul><li>Partial Penetration </li></ul><ul><li>Other Factors </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  10. 10. P T A – LARGE DIA <ul><li>DUG WELLS </li></ul><ul><li>Basically These are production Wells </li></ul><ul><li>Not Properly Designed For testing </li></ul><ul><li>Can Not Be Used Indiscriminately for Aquifer Performance test </li></ul><ul><li>Can Be Used For Yield Characteristics </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  11. 11. P T A – LARGE DIA <ul><li>Basic Objective Of a Test </li></ul><ul><li>Performance of a Well </li></ul><ul><li>Evaluation Of Hydraulic Parameters of the Aquifer </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  12. 12. P T A – LARGE DIA Large Diameter Well Excavations in the Ground to Shallow Depths having Significant Water Storage ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  13. 13. P T A – LARGE DIA <ul><li>Types </li></ul><ul><li>Masonary Wells </li></ul><ul><li>Wells With Pervious Lining </li></ul><ul><li>Kutcha Wells </li></ul><ul><li>Wells In Hard Rocks </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  14. 14. P T A – LARGE DIA <ul><li>Masonary Wells </li></ul><ul><li>Have Masonary Steining wall sunk in subsoil by applying static weight and simultaneously scooping out the earth from inside. </li></ul><ul><li>Entire water supply is drawn from from the pervious bottom </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  15. 15. P T A – LARGE DIA <ul><li>Wells With Pervious Lining </li></ul><ul><li>Wells Are Lined with cylinders of intertwined brush wood or bricks laid dry. </li></ul><ul><li>In between dry masonary some bands of pucca masonary are provided for stability </li></ul><ul><li>The wells are plugged at the bottom by concrete </li></ul><ul><li>Constructed in areas where yield potential is less </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  16. 16. P T A – LARGE DIA <ul><li>Kutcha Wells </li></ul><ul><li>These are Unlined Wells </li></ul><ul><li>Usually Dug in Hard Soils. </li></ul><ul><li>They Stand Vertically Without Lining </li></ul><ul><li>Relatively wider pit is dug upto just above water table. </li></ul><ul><li>Below which normally narrowed down usually lines with woven fabric of hemp stems or mattings etc. through which water oozes into the pit </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  17. 17. P T A – LARGE DIA <ul><li>Wells In Hard Rock Areas </li></ul><ul><li>Usually Open Excavated Pits through top soil mantle and weathered rocks. </li></ul><ul><li>Generally Constructed in Large sizes to provide storage and also in order to tap more joints, cracks or water bearing weathered zones. </li></ul><ul><li>Top portion is normally lined. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  18. 18. P T A – LARGE DIA Pumping Test Is A Controlled Field Experiment To Find Out The Hydraulic Characteristics Of An Aquifer Or The Yield Characteristics Of A Well ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  19. 19. P T A – LARGE DIA <ul><li>Types of Pumping Tests </li></ul><ul><li>Aquifer Tests </li></ul><ul><ul><li>A Pumping Test Performed to Determine the Hydraulic characteristics of an Aquifer. </li></ul></ul><ul><li>Yield Tests </li></ul><ul><ul><li>A Pumping Test which provides information about the yield and drawdown of a well. </li></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  20. 20. P T A – LARGE DIA <ul><li>Aquifer Test </li></ul><ul><li>Since the dug wells are not specifically designed to be used as test wells for evaluation of aquifer parameters, the selection of proper dug well needs utmost importance </li></ul><ul><ul><li>It should be representative of the aquifer </li></ul></ul><ul><ul><li>Design Should be such that most of the limiting conditions should be fulfilled. </li></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  21. 21. P T A – LARGE DIA <ul><li>Procedure For The Test </li></ul><ul><li>Water is pumped from a dug well at a constant discharge for a certain time. </li></ul><ul><li>The effect of the pumping i.e drawdown is measured in the pumped dug well and in some piezometers if provided in the vicinity of the dug well. </li></ul><ul><li>Recovery is also recorded after cessation of the pumping. </li></ul><ul><li>Drawdown/ recovery data is analysed using applicable method. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  22. 22. P T A – LARGE DIA <ul><li>Limitations Of Analysis </li></ul><ul><li>Definition of a Large Diameter Well </li></ul><ul><li>By Sammel (1974) </li></ul><ul><li>A well in which storage is large enough to produce significant errors when aquifer tests are analysed by methods which neglect well storage. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  23. 23. P T A – LARGE DIA <ul><li>Limitations Of Analysis </li></ul><ul><li>Basically Production Wells </li></ul><ul><li>Discharge from the Formation is always less than the Actual Discharge. </li></ul><ul><li>Cone of Depression starts from the walls of the well only after some time is elapsed. </li></ul><ul><li>A Seepage face is formed I.e the drawdown in the centre of the well is always more than the drawdown in the aquifer. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  24. 24. P T A – LARGE DIA <ul><li>Limitations Of Analysis </li></ul><ul><li>Even After cessation of pumping it is often recorded that water levels in the Observation wells continue to show decline. </li></ul><ul><li>In hard rock areas these wells are normally fully penetrating where as in alluvial areas generally these wells are partially penetrating. The flow will be from lateral as well as from the bottom. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  25. 25. P T A – LARGE DIA <ul><li>Preference </li></ul><ul><li>Preferably The analysis of pumping test data should be attempted for only those large diameter wells which can sustain long duration pumping and preferably provided with observation well/ wells. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  26. 26. P T A – LARGE DIA <ul><li>Yield test </li></ul><ul><li>Main Objective is to have an idea of the maximum quantity of water which can be pumped out from a dug well either by continuous or intermittent pumping. </li></ul><ul><li>It also reflects upon the yield characteristics of the aquifer tapped. </li></ul><ul><li>Helps in selection of pumps. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  27. 27. P T A – LARGE DIA <ul><li>Procedure For The Test </li></ul><ul><li>Water is pumped from a dug well for a sufficient time till either the well is emptied or the water level falls beyond the reach of the installed pumping device. </li></ul><ul><li>Drawdown and recovery data are recorded during pumping and after the cessation of pumping respectively. </li></ul><ul><li>Drawdown/ recovery data is analysed using applicable method for the evaluation of Yield characteristics. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  28. 28. P T A – LARGE DIA <ul><li>Limitation </li></ul><ul><li>The yield characteristics of a dug well is dependent on the saturated thickness of the aquifer tapped which shows a wide variation in different seasons especially in hard rock areas. </li></ul><ul><li>Hence yield test should be conducted for both pre and post monsoon seasons. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  29. 29. P T A – LARGE DIA <ul><li>Methods Available- Aquifer Tests </li></ul><ul><ul><ul><li>Slichter(1906) </li></ul></ul></ul><ul><ul><ul><li>Muskat (1937) </li></ul></ul></ul><ul><ul><ul><li>Hvorslev (1951) </li></ul></ul></ul><ul><ul><ul><li>Raju & Raghava Rao (1967) </li></ul></ul></ul><ul><ul><ul><li>Papadopulos – Cooper (1967) </li></ul></ul></ul><ul><ul><ul><li>Adyalkar & Mani (1972) </li></ul></ul></ul><ul><ul><ul><li>Kumara swamy (1973) </li></ul></ul></ul><ul><ul><ul><li>Zdankus (1974) </li></ul></ul></ul><ul><ul><ul><li>Boulton & Streltsova (1976) </li></ul></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  30. 30. P T A – LARGE DIA <ul><li>Methods Available- Aquifer Tests </li></ul><ul><ul><ul><li>Herbert – Kitching (1981) </li></ul></ul></ul><ul><ul><ul><li>Rushton and Holt (1981) </li></ul></ul></ul><ul><ul><ul><li>Rushton and Singh (1983) </li></ul></ul></ul><ul><ul><ul><li>Singh & Gupta (1986) </li></ul></ul></ul><ul><ul><ul><li>Roushton & Singh (1987) </li></ul></ul></ul><ul><ul><ul><li>Artificial Neural Networks </li></ul></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  31. 31. P T A – LARGE DIA <ul><li>Methods Available- Yield Tests </li></ul><ul><ul><ul><li>Karanjac (1975) </li></ul></ul></ul><ul><ul><ul><li>Saleem Romani (1973) </li></ul></ul></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  32. 32. P T A – LARGE DIA <ul><li>Slichter’s Method(1906) </li></ul><ul><li>Assumptions: </li></ul><ul><li>Large Diameter Well </li></ul><ul><li>Vertical Impervious Wall </li></ul><ul><li>Flow is Only From The Bottom </li></ul><ul><li>Procedure: </li></ul><ul><li>Well is Pumped For Some Time So That the water level in the well is depressed to a level less than safe working head. </li></ul><ul><li>Recovery performance is recorded. </li></ul>ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  33. 33. P T A – LARGE DIA Slichter’s Method(1906) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, C= Specific Capacity A= Cross sectional Area S1 = Drawdown when Pumping stopped S2 = Residual draw down at time t’ after pumping stops
  34. 34. P T A – LARGE DIA Slichter’s Method(1906) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Time Since Pumping Stopped is plotted on Arithmetic Scale and the Ratio between s1 and s2 is plotted on Logarithmic scale </li></ul><ul><li>Plot tends to fall on a straight line if the flow is only from the bottom </li></ul><ul><li>Take an arbitrary point on the line </li></ul><ul><li>Obtain t’ and s1/s2 for that point </li></ul><ul><li>Substitute in the equation and calculate C. </li></ul>
  35. 35. P T A – LARGE DIA Slichter’s Method(1906) Limitations ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Slichter ‘s equation is merely an expression for volume change of water in the well. </li></ul><ul><li>It has no theoretical validity in terms of flow into the well. </li></ul><ul><li>This can not be used to compare with specific capacity determined by the methods of Theis etc </li></ul><ul><li>However this can be used to compare the performance of dug wells of similar types. </li></ul>
  36. 36. P T A – LARGE DIA Muskat’s Method(1937) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Muskat Extended the use of Slichter’s equation for estimation of Transmissivity by combining Theim’s Solution for steady state flow. </li></ul>
  37. 37. P T A – LARGE DIA Muskat’s Method(1937) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, A = Cross Sectional Area r 0 = Distance at which drawdown is negligible at the end of pumping r w = Radius of the well s 1 = Drawdown at the time pumping stops s 2 = Residual Drawdown at time t’ after pumping stops.
  38. 38. P T A – LARGE DIA Muskat’s Method(1937) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Validity Of Theim’s Equation </li></ul><ul><li>Confined Aquifer </li></ul><ul><li>Lateral Flow into the well </li></ul><ul><li>Steady State </li></ul><ul><li>Validity Of Slichter’s Method </li></ul><ul><li>Flow in the well is only from the Bottom </li></ul>
  39. 39. P T A – LARGE DIA Muskat’s Method(1937) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Valid only for dug wells tapping confined aquifers with the well ending at the bottom of the confining Layer </li></ul><ul><li>Serious Limitation is to estimate the distance to a point of zero drawdown </li></ul><ul><li>Muskat & Slichter have assumed the value of r 0 to be in between 500 to 600 ft for Alluvial Aquifers. </li></ul>
  40. 40. P T A – LARGE DIA Adyalkar & Mani’s Method(1972) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Assumed that the value of r 0 to be in between 150 to 250 ft for Basaltic Aquifer when the Muskat equation is used for Unconfined Aquifers. </li></ul><ul><li>T=C’*580 </li></ul>
  41. 41. P T A – LARGE DIA Hvorslev Method(1951) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Based On Recovery Data </li></ul><ul><li>Takes Storage into Consideration </li></ul><ul><li>Very Similar To Slichter </li></ul><ul><li>Shape Factor is Introduced </li></ul><ul><li>Shape factor Depends on the radius Of the Well and the Nature of Intake Area. </li></ul>
  42. 42. P T A – LARGE DIA Hvorslev Method(1951) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, a = Well Radius S = Shape factor K = Permeability h 1 , h 2 = Drawdowns at t 1 and t 2 Times If water enters through base only the Shape Factor = 2* Diameter of the Well. Shape Factor was derived based on the studies from Small Diameter Wells.
  43. 43. P T A – LARGE DIA Raju & Raghav Rao Method(1967) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>This Method Describes a Procedure to Classify the Portion of the time – Drawdown Plot that can be utilised for the analysis. </li></ul><ul><li>Plot t versus Cumulative inflow </li></ul><ul><li>Find a part of the graph in which the data points fall nearly on a straight line </li></ul><ul><li>Apply Cooper – Jacob (1946) Straight Line method only for that particular data set. </li></ul>
  44. 44. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Felt That conventional methods for the estimation of T & S can not be applied in hard rock areas because of their anisotropy and occurrence of flow in the well through Fissure planes or conduits. </li></ul><ul><li>Hence Developed a mathematical equation defining the inflow into a well in hard rock areas. </li></ul>
  45. 45. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Assumptions </li></ul><ul><li>Flow into the well is only through Very minute Fracture Conduits or Fissure Planes opening through the inner surface of the well. </li></ul><ul><li>The water travels from an outer feeder Surface limited to Short extents from the well </li></ul><ul><li>The flow in the planes is laminar </li></ul><ul><li>The Operational depth of well is reckoned below the static water level. </li></ul><ul><li>No Flow Occurs above Static Water Level </li></ul><ul><li>No flow is assumed to enter the well through the bottom of the well. </li></ul><ul><li>The SWL outside Feeder Surface is not Declined. </li></ul>
  46. 46. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  47. 47. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, W= Hard Rock Permeability a = Cross Sectional Area D = Static Water Column d 1 = Water Column when pumping stopped. d 2 = Water Column at t R minutes t R = Time Taken For Recouperation
  48. 48. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, Q max = Maximum inflow Capacity Of the well w = Hard Rock Permeability D = Static Water Column
  49. 49. P T A – LARGE DIA Kumaraswamy Method(1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, t R (max) = Time Taken For 99% Recovery a = Area Of Cross Section D = Static Water Column Q max = Maximum inflow
  50. 50. P T A – LARGE DIA Zdankus Method(1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Aquifer has an apparently infinite areal extent. </li></ul><ul><li>In General Aquifer is Anisotropic </li></ul><ul><li>Unsteady State Flow into the well of large diameter becomes steady State Flow after some time due to its hydraulic parameters. </li></ul><ul><li>Aquifer is unconfined </li></ul><ul><li>Fully Penetrated. </li></ul><ul><li>Hydraulic Conductivity of the aquifer at the level of well is constant. </li></ul><ul><li>Well is pumped at a constant discharge. </li></ul><ul><li>Specific Yield of the aquifer is to be assumed. </li></ul>
  51. 51. P T A – LARGE DIA Zdankus Method(1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  52. 52. P T A – LARGE DIA Zdankus Method(1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Modified the Theis Unsteady Confined Radial Flow Equation Where, K =Hydraulic Conductivity U = Drawdown Function Q i = Discharge of Ground Water inflow into the well R = Conditional Radius of Influence r w = Radius of the Well
  53. 53. P T A – LARGE DIA Zdankus Method(1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, U = Drawdown Function H = Thickness Of The Saturated Zone s 0 = Drawdown in the aquifer recorded on the wall of the well or in the observation well.
  54. 54. P T A – LARGE DIA Zdankus Method(1975) Inflow discharge during Pumping ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, Q i = inflow discharge Q = Discharge of Water Pumped r w = Radius Of Well  s’ 0 = Decline in Water level in the well per  t Time interval.
  55. 55. P T A – LARGE DIA Zdankus Method(1975) Inflow discharge during Recovery ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, Q i = inflow discharge r w = Radius Of Well  s’ 0 = Rise in Water level in the well per  t Time interval.
  56. 56. P T A – LARGE DIA Zdankus Method(1975) Conditional Radius Of Influence ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, R = Conditional Radius Of Influence S Y = Specific Yield H = Thickness Of The Saturated Zone s 0 = Drawdown in the aquifer recorded on the wall of the well or in the observation well. K = Hydraulic Conductivity
  57. 57. P T A – LARGE DIA Zdankus Method(1975) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Record drawdown in the well as well as in the aquifer for each time step </li></ul><ul><li>Compute decline/ increments of water levels for each time step </li></ul><ul><li>Calculate inflow discharge for each step </li></ul><ul><li>Compute drawdown function for each time interval. </li></ul><ul><li>Compute mid time for each time interval. </li></ul><ul><li>Determine the value of Q i /2  U </li></ul><ul><li>Assume S Y and Compute values of K by trial and error method. </li></ul>
  58. 58. P T A – LARGE DIA Papadopulos - Cooper Method(1967) Assumptions & Conditions ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Aquifer has an apparently infinite areal extent. </li></ul><ul><li>Aquifer is homogeneous, isotropic and of uniform thickness over the area of influence. </li></ul><ul><li>Prior to pumping the phreatic/piezometric surface is horizontal. </li></ul><ul><li>Discharge is constant. </li></ul><ul><li>Pumped well penetrates entire aquifer – Horizontal Flow </li></ul><ul><li>Storage can not be neglected. </li></ul><ul><li>Aquifer is confined </li></ul><ul><li>Flow is in unsteady state. </li></ul><ul><li>Well losses are negligible. </li></ul>
  59. 59. P T A – LARGE DIA Papadopulos - Cooper Method(1967) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  60. 60. P T A – LARGE DIA Papadopulos - Cooper Method(1967) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, s = drawdown Q= discharge T= Transmissivity
  61. 61. P T A – LARGE DIA Papadopulos - Cooper Method(1967) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, s w = drawdown inside the well Q= discharge T= Transmissivity
  62. 62. P T A – LARGE DIA Papadopulos - Cooper Method(1967) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Get Or Plot Master Curve on Double Log F(  ,  ,  ) Vs  </li></ul><ul><li>Plot on Another Double Log s Vs t </li></ul><ul><li>Superimpose – such that most of the points match </li></ul><ul><li>Choose an Arbitrary point </li></ul><ul><li>Get values s, t, F(  ,  ,  ),  for the match point </li></ul><ul><li>Substitute in the equation to get T </li></ul><ul><li>Calculate S </li></ul><ul><li>For reliable results sufficient part of data curve should match with master curve. </li></ul>
  63. 63. P T A – LARGE DIA Roushton and Singh Method(1982) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Papdopulos and Cooper Type Curves show a straight line behavour in the early part of the data curve corresponding to storage effect. </li></ul><ul><li>Due to the similarities of the curves for different storage coefficients, some times difficult to identify appropriate type curve. </li></ul><ul><li>Roushton & Singh gave an alternate approach to overcome this. </li></ul><ul><li>Introduced well drawdown ratio </li></ul>
  64. 64. P T A – LARGE DIA Roushton and Singh Method(1982) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Drawdown ratio normally varies from 2.5 to 1 </li></ul><ul><li>Initially when water comes from the storage the ratio will be 2.5 </li></ul><ul><li>When in equillibrium conditions it approaches 1 </li></ul>
  65. 65. P T A – LARGE DIA Roushton and Singh Method(1982) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Drawdown ratio Vs Time Function </li></ul><ul><li>Data Plot Drawdown Vs t </li></ul><ul><li>Data Plot need to be matched with the type curve. </li></ul><ul><li>Get values for the match point </li></ul>
  66. 66. P T A – LARGE DIA Boulton and Streltsova Method(1976) Assumptions & Conditions ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Aquifer is Compressible and Anisotropic </li></ul><ul><li>Underlain by horizontal impermeable bed </li></ul><ul><li>Pumped at Constant rate. </li></ul><ul><li>Well losses are negligible. </li></ul>
  67. 67. P T A – LARGE DIA Boulton and Streltsova Method(1976) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  68. 68. P T A – LARGE DIA Boulton and Streltsova Method(1976) Assumptions & Conditions ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Q = Discharge </li></ul><ul><li>s = Drawdown </li></ul><ul><li>S= Storage Coefficient </li></ul><ul><li>T = Transmissivity </li></ul><ul><li>r = horizontal distance </li></ul><ul><li>r w = radius of the well </li></ul><ul><li>y = depth of any point below water table </li></ul><ul><li>y’ = y/h </li></ul><ul><li>=  r/h </li></ul><ul><li> w =  r w /h </li></ul>l = Distance from water table to bottom of the unlined part of the abstraction well. l 1 = Distance from water table to the top of the unlined portion l’ = l/h l’ 1 = l’/h
  69. 69. P T A – LARGE DIA Boulton and Streltsova Method(1976) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>If the values of l’,y’,  and r/rw are near to those values given, this method can be applied. </li></ul><ul><li>If they are not matching trial and error method can be adopted </li></ul><ul><li>W vs  on double log paper for different values of r/rw </li></ul><ul><li>s Vs t data curve </li></ul><ul><li>Superimpose for a match </li></ul><ul><li>Choose an arbitrary point </li></ul><ul><li>Get values of W,  , s,t and note down  of the type curve. </li></ul><ul><li>Substitute in the equation to Calculate T </li></ul><ul><li>Calculate S by substituting r,  , t and T. </li></ul><ul><li>For Computing Specific Yield Type B Curves Should Be Used </li></ul>
  70. 70. P T A – LARGE DIA Singh & Gupta Method (1986) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>A numerical Modeling Method </li></ul><ul><li>Applicable even when abstraction rate is not constant </li></ul><ul><li>Breaking the entire test into number of equal time steps. </li></ul><ul><li>Calculate the response of the aquifer from each of the time step. </li></ul><ul><li>Abstraction rate is assumed constant during each step. </li></ul><ul><li>Drawdown is small compared to saturated thickness of the aquifer. </li></ul><ul><li>Seepage face is neglected. </li></ul>
  71. 71. P T A – LARGE DIA Singh & Gupta Method (1986) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  72. 72. P T A – LARGE DIA Singh & Gupta Method (1986) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Basically Iterative Process and Calculates the Drawdowns with the assumed T & S Values . </li></ul><ul><li>It Should be repeated till the error in between measured and observed drawdown is within permissible limit. </li></ul>
  73. 73. P T A – LARGE DIA ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Artificial Neural Networks
  74. 74. P T A – LARGE DIA Yield Test ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Main Objective is to have an idea of the maximum quantity of water which can be pumped out from a dug well either by continuous or intermittent pumping. </li></ul><ul><li>It also reflects upon the yield characteristics of the aquifer tapped. </li></ul><ul><li>Helps in selection of pumps. </li></ul>
  75. 75. P T A – LARGE DIA Karanjac’s Method (1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>When a Large diameter well is pumped at a Constant Discharge ( Qp) for a known time (tp), the total volume of the water discharged from the well can be separated into two parts </li></ul><ul><ul><li>Volume of water stored in the well between pre and post pumping levels. </li></ul></ul><ul><ul><li>Volume of water aquifer yields </li></ul></ul>
  76. 76. P T A – LARGE DIA Karanjac’s Method (1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Where, Q r = inflow rate during well recovery t r = time taken for the recovery Q p = Rate of pumping t p = Time taken for pumping
  77. 77. P T A – LARGE DIA Karanjac’s Method (1975) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Used the value of Q r to define the optimum yield of the well </li></ul><ul><li>If a well is pumped at this discharge, the well will never go dry. </li></ul>
  78. 78. P T A – LARGE DIA Karanjac’s Method (1975) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Pump the well till substantial drawdown is created </li></ul><ul><li>Measure the discharge(Q p ) and pumping time(t p ) </li></ul><ul><li>Stop the pump and record the time needed for recouperation (t r ) </li></ul><ul><li>Calculate the Optimum yield. </li></ul>
  79. 79. P T A – LARGE DIA Karanjac’s Method (1975) Comments ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Difficult to know the time of complete recouperation </li></ul><ul><li>Q r is always a fraction of the installed pump capacity </li></ul><ul><li>On low transmissivity areas it is very difficult to pump with Q r . </li></ul>
  80. 80. P T A – LARGE DIA Romani’s Method (1973) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Record Static Water Level </li></ul><ul><li>Pump the well with constant discharge. </li></ul><ul><li>Record Drawdown with time </li></ul><ul><li>Record the time at which the well is dry or the well reaches the optimum lifting capacity of the pump(t 1 ) </li></ul><ul><li>Record recouperation with time after stopping the pump. </li></ul>
  81. 81. P T A – LARGE DIA Romani’s Method (1973) ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS
  82. 82. P T A – LARGE DIA Romani’s Method (1973) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Plot dd/rdd vs time on arithmetic paper </li></ul><ul><li>Draw a line of 50% recovery </li></ul><ul><li>Record time to empty 50% of the well (t 2 ) </li></ul><ul><li>Record time for 50% recovery (t 3 ) </li></ul><ul><li>Compute n </li></ul>
  83. 83. P T A – LARGE DIA Romani’s Method (1973) Procedure ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS <ul><li>Compute Optimum Yield </li></ul>
  84. 84. P T A – LARGE DIA ANALYSIS OF PUMPING TEST DATA LARGE DIAMETER WELLS Thank You

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