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Rainwater Harvesting
EVR 5332 Integrated Solutions forWater in Environment and
Development
November 5, 2007
John Stiefel Research AssistantGlobal Water for Sustainability (GLOWS) Program
Florida International University
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Rainwater harvesting (RWH):
= the collection and storage of rainwater insurface or sub-surface reservoirs, therebyreducing water losses to runoff and evaporation
(1) the direct capture and storage of rainwater for future humanuse
(2) manipulation of the landscape to slow and harness runofffrom rainfall
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Rainwater harvesting in arid areas
Map courtesy of United States Geographical Surveyhttp://pubs.usgs.gov/gip/deserts/what/world.html
http://pubs.usgs.gov/gip/deserts/what/world.htmlhttp://pubs.usgs.gov/gip/deserts/what/world.html -
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RWH in highly seasonal climates
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INDIA:the worldsleader in
RWH
http://images.google.com/imgres?imgurl=http://www.cnn.com/2000/ASIANOW/south/08/01/india.rain.ap/story.india.rain.jpg&imgrefurl=http://www.cnn.com/2000/ASIANOW/south/08/01/india.rain.ap/index.html&h=168&w=220&sz=12&hl=en&start=33&tbnid=xShvySCY-MRxvM:&tbnh=82&tbnw=107&prev=/images%3Fq%3Drain%2Bindia%26start%3D18%26ndsp%3D18%26svnum%3D10%26hl%3Den%26lr%3D%26sa%3DN -
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Rooftoprainwaterharvesting
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Anicut
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Anicut
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Nadi / Johad
Source: adapted from Sukhija et al., 2005
T k
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Tanka
L d b di / il b di
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Land bunding / soil bunding
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RWH is a technology that can be applied in bothurban and rural areas
Several RWH approaches have been used and
many may be climate or eco-region specific
RWH can be implemented and managed at
various levels City level
Village level
Household level
RWH in an IWRM context
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Many international organizations and
governments are promoting RWH as astrategy for improving access to watersupply
Example: seasonal variability in water supply
RWH is being applied to demonstratecorporate social consciousness and as asolution to conflicts Example: groundwater mining
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The case of
Coca-Cola Environmental and
social problems in India;
intense use ofgroundwater
Criticism on the basis ofclaims that thecompany is depletinggroundwater resourcesto make Coke 9L of water = 1L of Coke
Many people are angry
and want Coke out ofIndia
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Coca-Colas response
In June 2002, began implementing RWH as awater conservation program Specific objective was to increase groundwater
recharge
By 2006, had RWH programs at 26 bottlingplants in India and in 9 communities
Claim to have harvested 1.65 million m3rainwater in 2005 Amount corresponds
to 56% of groundwaterwithdrawn by Coke inthat year
Plans to expand RWHinitiatives throughout IndiaSource: BusinessWeek 2/10/2003
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Considerations:
Rooftop rainwaterharvesting
Pros and cons? Pros:
Can provide a clean watersource, especially in urban
areas Can decrease urban
flooding
Groundwater recharge
increased through artificialrecharge
Cons:
Should not be a substitutefor a solution to problemsof surface water quality
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Considerations:
land and soilbunding
Pros and cons? Pros: Decreases runoff and
makes water available for
agriculture Cons:
Causes majormodifications to the way
water moves through thelandscape
Could deplete surfacewater resources in
downstream areas
C id ti RWH f
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Considerations: RWH forgroundwater recharge
Pros and cons? Pros:
Can recharge shallowaquifers
Cons: Traditional RWH doesnt
recharge water indeeper, confinedaquifers
Downstream impact
Few scientific studieshave actually examinedthe effectiveness ofRWH for groundwaterrecharge
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SUMMARY RWH is an old technique used to capture and store
water for human use
Used to improve access to water supply especially inarid regions or highly seasonal climates
Cost-effective and applicable at many scales;decentralized in nature
Needs to be considered alongside other approaches for
water supply and storage, and in an IWRM context
A need more information on the groundwater rechargedynamic of RWH.
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THE EFFECTIVENESS OF RAINWATER HARVESTING FORTHE ARTIFICIAL RECHARGE OF GROUNDWATER IN THE
WAKAL RIVER BASIN, INDIA
John M. Stiefel Research Assistant
Global Water for Sustainability (GLOWS) Program
Florida International University
Masters Thesis Research
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Study Area
The Wakal River Basinoriginates at an altitudeof 762 m in the Aravalli
Hills of southernRajasthan
Catchment area of 1,625km2
Source of the greaterSabarmati River Basin
Trans-boundary riverflowing 371 km throughRajasthan and Gujaratbefore discharging into the
Arabian Sea
W t S it i R j th
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Increasing demand for water has led to over-exploitation of the groundwater resources Only 32 of the 236 blocks (sub-districts) in
Rajasthan are categorized as safe, with respect totheir groundwater resources
General decline in the water table Increase in groundwater quality problems
Groundwater is the primary source ofreliable water supply in Rajasthan 90% of the drinking water and 60% of water
used for irrigation
Water Scarcity in Rajasthan
Rajasthan is Indias driest and mostdrought prone state 10% of Indias geographic area, along with 5%
of its population, yet it contains only 1% of the
nations total surface water resources
K l d G
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Knowledge Gap
Rajasthan and Gujarat have been at the center of a majorgrassroots mass movement to revive rainwater harvesting for thelast two decades.
Recent government investments to promote rainwater harvesting.
A lack of technical evaluations of RWH has prevented theseinvestments to be properly scrutinized
Many RWH structures are built without a clear understanding of their hydrologicimpact
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Research Objectives
Research Objectives:1. To contextualize the rainwater harvesting efforts in the
larger hydrologic context2. To quantify the amount of artificial recharge added to
groundwater supplies
3. To determine the impact of artificial recharge on thequality of groundwater.
Research Goal: to assess the
effectiveness of rainwaterharvesting for the artificialrecharge of groundwater in the
Wakal River Basin, India
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Research Objectives
Research Objectives:1. To contextualize the rainwater harvesting efforts in the
larger hydrologic context2. To quantify the amount of artificial recharge added
to groundwater supplies
3. To determine the impact of artificial recharge onthe quality of groundwater.
Research Goal: to assess the
effectiveness of rainwaterharvesting for the artificialrecharge of groundwater in the
Wakal River Basin, India
St d Sit
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UPPER PortionLOWER Portion
Study Sites
Nadi:medium-large earthen damAnicut:small-medium masonry dam
St d Sit
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Study Sites
Anicut Anicut
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Methods
Field Methods:
Groundwater tracers Groundwater level measurements
Groundwater quality measurements
Reservoir Mapping
Analytical Methods:
GIS analysis tools
Geochemical mixing models
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Results & Discussion
Impact of Artificial Recharge on Groundwater Supplies
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Artificial Recharge Lower Portion Upper Portion
Depth (mm) 94 107
Area of Influence (m2) 50,000 250,000
Volume (m3) 4,682 26,659
Impact of Artificial Recharge on Groundwater Supplies
How much artificial recharge is added to groundwater?
Impact of Artificial Recharge on Groundwater Supplies
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Artificial Recharge Lower Portion Upper Portion
Depth (mm) 45 44
Area of Influence (m2
) 37,600 44,300Volume (m3) 1,701 1,958
Impact of Artificial Recharge on Groundwater Supplies
Impact of Artificial Recharge on Groundwater Supplies
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StudySite
RWHStructure
Area ofInfluence
(m2)
2006 Rateof ArtificialRecharge(mm/yr)
Jharapipla JP.Dam 250,000 107
50,000
44,300
37,600
Jharapipla LY.ANI 94
Godawara GD.ANI 44
Godawara GD.ANI(2) 45
Impact of Artificial Recharge on Groundwater Supplies
ArtificialRecharge
(m3)
4,682
1,958
1,701
Implication: the amount of artificial recharge can varysignificantly between similar anicutslocated a mere 10 kmapart
Artificial Recharge in Context of Rural Water Supply
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Artificial Recharge in Context of Rural Water Supply
Study SitePortionof Site
ArtificialRecharge
within Areaof Influence
(TCM)
ApproximateTotal Annual
Withdrawal withinthe Study Area
(TCM)
Upper Portion(JP.Dam)
26.7 60.1
Lower Portion(LY.ANI)
4.7 43.7
Upper Portion(GD.ANI)
2.0 15.0
Lower Portion(GD.ANI(2))
1.7 15.2Godawara
Jharapipla
*TCM = thousand cubic meters
Artificial recharge vs. withdrawal
Larger Nadiaugments 44% of 2006groundwater withdrawal
Smaller Anicutsaugment between 11-13% of 2006 groundwater withdrawal
11.2%15.21.7Lower Portion(GD.ANI(2))
13.0%15.02.0Upper Portion(GD.ANI)
Godawara
10.7%43.74.7Lower Portion(LY.ANI)
44.3%60.126.7Upper Portion(JP.Dam)
Jharapipla
Artificial Rechargeto Groundwater
Withdrawal Ratio
ApproximateTotal Annual
Withdrawal withinthe Study Area
(TCM)
ArtificialRecharge
within Areaof Influence
(TCM)
Portionof Site
Study Site
Implication: artificialrecharge compensates a
significant portion ofannual groundwaterwithdrawal
Impact of Artificial Recharge on Groundwater Quality
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Impact of Artificial Recharge on Groundwater Quality
Chloride(mg/l)
Sulfate(mg/l)
Fluoride(mg/l)
ElectricalConductivity
(S/cm)
Alkalinity(CaCO3)
(mg/l)
TotalHardness(CaCO3)
(mg/l)
CalciumHardness(CaCO3)
(mg/l)
MagnesiumHardness(CaCO3)
(mg/l)
TotalDissolved
Solids(mg/l)
Turbidity(NTU)
ReceivesArtificialRecharge
Mean 82.8 37.0 0.3 800.0 244.3 185.0 128.0 57.0 455.0 1.3
(JP.DW3,LY.DW1)
S.E. 6.1 11.0 0.1 27.5 7.9 9.0 5.9 4.4 29.9 0.2
NoArtificialRecharge
Mean 102.7 55.3 0.8 866.8 236.2 251.3 158.7 92.7 466.7 5.3
(JP.UW1,GD.UW2,GD.DW2)
S.E. 21.1 14.0 0.3 86.9 30.9 28.1 16.0 12.9 39.2 0.8
How does artificial recharge effect groundwater quality?
Impact of Artificial Recharge on Groundwater Quality
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p g Q y
Chloride(mg/l)
Sulfate(mg/l)
ElectricalConductivity
(S/cm)
Receive Artificial Recharge Mean 96.6 6.0 827
JP.DW2, JP.DW3, LY.DW0,
LY.DW1, LY.DW2, LY.DW3,GD.DW0, GD.DW3,GD.DW4 S.E. 10.8 0.5 32
No Artificial Recharge Mean 109.1 11.8 939
JP.UW1, JP.DW5, JP.DW4,GD.UW2, GD.DW2,GD.DW6 S.E. 10.8 1.0 28
The water quality pattern is maintained forthe larger data set.
An ANOVA on this data reveal that thereis a significant difference (p
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Conclusions
Groundwater supply: Artificial recharge compensates a significant
portion (11-44%) of annual groundwaterwithdrawal
The amount of artificial recharge can varysignificantly between similar anicutslocated amere 10 km apart
Groundwater quality: Artificial recharge improves groundwaterquality through the dilution of many chemical
constituents
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QUESTIONS?