Characterization of seasonal effects on the specific capacity of - - PowerPoint PPT Presentation

▶
characterization of seasonal effects on the specific
SMART_READER_LITE
LIVE PREVIEW

Characterization of seasonal effects on the specific capacity of - - PowerPoint PPT Presentation

Oct 15, 2022 11 likes •264 views

Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua Essa L. Gross and John S. Gierke Department of Geological Eng. & Sciences Michigan Technological University

slide-1
SLIDE 1

Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua

Essa L. Gross and John S. Gierke Department of Geological Eng. & Sciences Michigan Technological University Antoinette Kome SNV Nicaragua

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-2
SLIDE 2

Outline

Problem Statement Research Objectives Study Area Study Area Methodology Results Conclusions

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-3
SLIDE 3

Problem Statement

  • Practically no information

exists on the productivity of rural wells in developing countries.

  • Policy makers have no

information to base decisions or to develop water management plans. water management plans.

  • The lack of technical and

economic resources prevents the collection of performance and monitoring data.

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock- aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-4
SLIDE 4

Design and test a method to characterize the productivity of existing rope-pump wells in rural areas of developing countries

Research Objectives

Monitor seasonal changes in SWLs and specific capacities of rope-pump wells in an area that experiences distinct rainy and dry seasons.

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-5
SLIDE 5

Outline

Problem Statement Research Objectives Study Area Study Area Methodology Results Conclusions

E.L.Gross, "Characterization of seasonal effects on the specific capacity

  • f rope-pump wells in a fractured rock-

aquifer in Nicaragua” AWRA

slide-6
SLIDE 6

Study Area

Santa Rita

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock- aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-7
SLIDE 7

Regional Geology

  • Tpc - Coyol Group

Fractured ignimbrites, tuff, andesite, basalt

  • Source: INETER

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-8
SLIDE 8

Rope-pump well

60’

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-9
SLIDE 9

Outline

Problem Statement Research Objectives Study Area Study Area Methodology Results Conclusions

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-10
SLIDE 10

Testing and Monitoring Approaches

  • Monthly manual pump tests in triplicate at 3 wells
  • Each test conducted to attain pumping, equilibrium, and recovery

phases

  • A conventional step-drawdown test performed in one well

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-11
SLIDE 11

Pump test regime

  • Pump 60 – 90 gal
  • Approximate rate
  • f 5 gpm

Well 2 - 2/10/07

  • 0.5

0.0 0.5 20 40 60 80 100 120 140 160 180 200 Elapsed time (min)

  • f 5 gpm
  • Allow well to

recover for an hour

  • r more
  • Triplicate tests
  • 4.0
  • 3.5
  • 3.0
  • 2.5
  • 2.0
  • 1.5
  • 1.0

Drawdown (ft)

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-12
SLIDE 12

Recuperation Pumping

Explanation

Well 2: 1/11/07

  • 3.00
  • 2.00
  • 1.00

0.00

down (ft)

Test 1 levelogger Test 2 levelogger Test 3 levelogger Test 3 sounder

Equilibrium drawdown

  • 6.00
  • 5.00
  • 4.00
  • 3.00

500 1000 1500 2000 2500 3000 3500

Elapsed Time (sec) Drawdow

Test 3 sounder Test 2 sounder Test 1 sounder

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-13
SLIDE 13

Equilibrium drawdown Data analysis method

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-14
SLIDE 14

Pump and recovery curves Data analysis methods

Log Log

s s’

S r Tt T s Q

2

3 . log 264 =

Cooper-Jacob Approximation in “Conventional” Units:

JSL: T=264 Q/ s JSL: T=264 Q/ s’

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-15
SLIDE 15

Outline

Problem Statement Research Objectives Study Area Study Area Methodology Results Conclusions

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-16
SLIDE 16

Change in static water level

  • Average dry season drop = 6 ft

DRY RAINY

  • 10/22/06

12/11/06 1/30/07 3/21/07 5/10/07 6/29/07 8/18/07 10/7/07 11/26/07

DRY RAINY

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-17
SLIDE 17
slide-18
SLIDE 18

Specific Capacity Changes

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Well 1 Well 2 Well 4

Specific capacity (attained from recovery data) vs. SWL

Well Change SWL (ft) Change SWL (% available water column)* % Change Specific Capacity 1 6.6 4 % 15 % 2 4.4 2.5 % 26 % 3 6.3 3.5 %

  • 4

7.9 4.8 % 81 %

*Assuming 200’ well

0.0 0.2 0.4

  • 1.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 Feet below SWL Dec 06

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-19
SLIDE 19

Well 1 0.0 0.5 1.0 1.5 2.0 2.5

Non- equilibrium recovery curve Equilibrium approx Linear (Non-

Analysis method comparison

Well 2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 25.5 26.5 27.5 28.5 29.5 30.5 31.5

Equilibrium approx Non- equilibrium method - recovery curve Non- equilibrium method - pump curve Linear

Factor

  • f 2

Factor

  • f 2

36.0 38.0 40.0 42.0 44.0 Static Water level (ft btc) 25.5 26.5 27.5 28.5 29.5 30.5 31.5 Static Water Level (ft btc) Well 4 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 35 36 37 38 39 40 41 42 43 44 SWL (ft btc)

Equilibrium approx Non-equilibrium method - recovery curve Non-equilibrium method - pump curve Linear (Non-

Factor

  • f 2
  • Spec. cap values

calculated from : equilibrium approx recovery curve pump curve

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-20
SLIDE 20
  • ! "

""

slide-21
SLIDE 21

Well 4 2.0 2.5 3.0 3.5 4.0

Equilibrium approx Non-equilibrium method - recovery curve Non-equilibrium method - pump curve

  • Spec. cap values

calculated from manual tests: equilibrium approx recovery curve pump curve

Conventional pump test comparison

0.0 0.5 1.0 1.5 2.0 35 36 37 38 39 40 41 42 43 44 SWL (ft btc)

curve Trad Equilibrium approx Trad Non- equilibrium-pump curve Trad Non- equilibrium- recovery curve

  • Spec. cap values

calculated from conventional test: equilibrium approx recovery curve pump curve

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-22
SLIDE 22

Outline

Problem Statement Research Objectives Study Area Study Area Methodology Results Conclusions

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-23
SLIDE 23

Conclusions (1 of 2)

On method:

Manual test pump rate low, but results are representative of well behavior at high rates (in this case 7 times higher). Recovery data easiest to collect and yields Recovery data easiest to collect and yields accurate specific capacity values. Overestimated specific capacity of wells as determined by equilibrium drawdown method maybe caused by lack of understanding of geology. Modifications to well for manual pump test minor, economical.

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock- aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-24
SLIDE 24

Conclusions (2 of 2)

On seasonal effects:

Current water demands not affected by seasonal change in the static water level. level. Method determined that max capacity

  • f wells to be at least 10X greater than

what rope pump well delivers. Observed changes in productivity with even slight changes in SWL.

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock- aquifer in Nicaragua” AWRA conference, Alb, NM 2007

slide-25
SLIDE 25

Thank You

Financial Support:

  • National Science Foundation PIRE 0530109
  • DeVlieg Foundation
  • SNV Nicaragua
  • U.S. Peace Corps

We would like to acknowledge the following people for their assistance in this study: Gregg Bluth, Fernando Flores, Luis Meza, Denia Acuña, Evelio Lopez , Ivan Palacios, Elisena Medrano, Luis Palacios, Beth Myre, and the Families of Santa Rita

E.L.Gross, "Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua” AWRA conference, Alb, NM 2007