This document describes a project to improve water yields for villages in Tanzania through rainwater harvesting and artificial groundwater recharge. A 1989 water scheme was experiencing declining yields, so from 2006-2014 monitoring and pilots were conducted. A strategy of increasing groundwater recharge through rainwater infiltration was tested. A hillside dam and infiltration pits successfully recharged an estimated 2.5 million liters, increasing dry season yields from 0.3 to 0.8 liters/second. Proper maintenance and community involvement were important to the project's sustainability. While challenges remain, the results demonstrate that rainwater harvesting can significantly improve rural water supplies.

1. Rainwater harvesting and artificial
groundwater recharge to improve
Kwemakame Spring Yields
Harry Rolf
SamSamwater
27/10/2014

2. Project Location
• Tanga region
• Lushoto district
• Kwemakame / Kwai villages

3. Kwemakame project history
• Chamavita, Mr. Kempenaar and mama Els
• 1989 scheme construction
– 10 intakes
– 2500 - 3500 users
• 2004 ‘depletion’>Tsedaka>AquaforAll>Chamavita
• 2006 practicalresearch project
– Cause of depletion?
– How to improve?

4. project history (2)
• 2006 – 2010
• Monitoring
• Field investigations
• Analysis
• 2009 understanding > strategy>pilots
• 2010/2012 pilot design & construction
• 2013 ‘post-pilot’ monitoring and reporting
• 2014 dissemination

5. Partner Project
Local Partners:
• Village Kemakame/Kai
• Chamavita
(Chama cha maendaleo vijijini tanga)
• Pangani Basin Water Office
The Netherlands:
• AquaforAll (funding)
• Aquanet (funding)
• PWN/SamSamWater (techn.
Assistance)
• SPOT Tanzania

6. Kwemakame/Kwai
Estimated 3000 people
• Kwai/Kwemamake Water Board
• 9 sub-villages/hamlets each having
water committee
• 34 tap watercommitees
Water demand 1 liter/sec
Scheme constructed 1989, but the yield
dropped since the initiation
Present Water sources (dry season):
• Dindira ‘spring’ catchment (0,35 l/sec)
• Kidandi ‘spring’catchment (0,15 l/sec)
Total yield Dindira
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
01/01/11
01/03/11
01/05/11
01/07/11
01/09/11
01/11/11
01/01/12
01/03/12
01/05/12
01/07/12
01/09/12
01/11/12
01/01/13
01/03/13
01/05/13
01/07/13
dischargeinl/sec
tot flow monthly avg
estimated demand (including animals)
domestic only
Kidandi sourc

7. Study area
Water catchment is up in the mountains at Dindira

8. Dindira Valley 1950 – 2000 masl

9. Bedrock outcrop

10. Dindira shallow aquifer
Impervious base
2100 m
2000 m
1950 m

11. Gravity spring captation
Impervious base
Rainfall and
evapotranspiration
Recharge
runoff
spring
spring
‘spring’ wall intake

12. Water intakes

13. Water scheme
ch. 6
chamber 5
intake 8
intake 9
intake 10
intake 11
chamber 2
other
intakes
storage tank
to Kwemakame
From 11 intakes to 5 collection chambers
From collection chambers to storage tank
From storage tank down to village distribution

14. Dindira main Storage tank 1850 m

15. 43000 LITER/DAG
17 LITER PER PERSON
Distribution area 1650 m

16. Water point Dindira hamlet

17. Research methodology
• Monitoring (Rainfall, evaporation, yields,…)
• Field reconnaisance
• Mapping
• Analysis/ understanding

18. Monitoring
Rainfall & pan evaporation

19. Training
data collectors

21. Discharge reading in collection chambers

22. Bucket method

24. Groundwater levels

25. Field investigations
• GPS mapping
• Geophysical sounding and profiling
• Augering
• Infiltration capacity testing
• Water chemistry & temperature

26. GPS mapping

27. Geo electrical profiling (VES and Wenner)

30. Full cross-valley Wenner
profile

31. Conductivity of black clay

32. Auger drilling

33. Training water meter

34. Water quality testing

35. Analysis
Wenner profile Dindira (Kwemakame) intake nr.2 sub-catchment
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
-10 -7.5 -5 -2.5 0 2.5 7.5 10 12.5 17.5 20 22.5 27.5 30 32.5 37.5 40 42.5 47.5 50 52.5 57.5 60 62.5 67.5
distance from centre (m)
altitude(m)
100
1000
1000
groundsurface (waypoints)
ground surface (interpret)
apparent res (Ωm) 3x5m
apparent res (Ωm) 3x10m
outcrop
Aquifer properties
Cumulative rainfall
0
200
400
600
800
000
200
Nov Dec Jan Feb March April May June July August Sept Oct
Dindira 2007/2008
Dindira 2008/2009
Normal Rainfall (NewLocClim)
Normal rainfall Lushoto
Dindira 2009/2010
Rainfall analysis
Kwemakame total discharge
0
10
20
30
40
50
60
jan/08
mrt/08
mei/08
jul/08
sep/08
nov/08
jan/09
mrt/09
mei/09
jul/09
sep/09
nov/09
jan/10
mrt/10
mei/10
jul/10
sep/10
rainfall(mm/day)
0
0.5
1
1.5
2
2.5
3
3.5
discharge(l/sec)
rainfall (mm
flow in ch 5
27/10/06 chamber 5
Rainfall discharge
relationship

36. Reasons for depletion
• Over decades: springs dried up due to
deforestation.
• Rapid population increase
• Climate change? (no proof)
• Since 1989: yield decreased because of using up
groundwater storage

37. Reasons for depletion (2)
Just too little recharge
Most of the water is running off , being lost out of the area
Intakes are just ‘scraping’ the recharge added in the last
rain season
Groundwater dropping

38. Key to improvement
INCREASE THE AMOUNT OF WATER THAT INFILTRATES INTO THE GROUND
Water is available:
A lot of water in running off unutilized

39. runoff

40. Strategy options
• Plant trees (yes, good solution but on the long run)
• (Let it rain more)
• (Pump water)
• (Deeper intake wall)
• (Surface water storage and treatment)
• Add water in the underground:
–‘artificial recharge’

41. Strategy to improve
Artificial Recharge:
– Harvest rainwater that is running of
– Temporary storage
– Infiltration in the underground
– ‘boost’ groundwater > increase yield
3R
Retention
Recharge
Re-use

42. Pilots to prove strategy
Pilot 1
Rainwater harvesting and artificial
groundwater recharge

43. )
PILOT DESIGNS 2009

52. runoff
Existing intake
nr 2
Infiltration pit
filter trench
storage
(hillside) dam
Pilot 1

54. Hillside dam location

57. Runoff catchment & diversion channel

58. Hillside dam

59. Infiltration pit

60. Filter trench and infiltration pit

61. SHIDA KUBWA
Rain disaster
April 2012
Dam restored
and enforced
summer 2012

62. Fillings of the dam Dec 2012 – May 2013

63. Run off

64. Run off from bedrock

65. Water diversion to the dam

66. Fillings of the reservoir

67. Infiltration through the reservoir bottom

68. Release to the infiltration pit
(after 1 day settling)

69. Results
A total amount of 2,5 million liters has been infiltrated
This water is added to groundwater and slowly flows down to
intake, flowing out in the dry season
Some intakes were closed. By doing that, groundwater is
conserved for the dry season. This has been beneficial as
well.

70. 2013 dry season effect:
The people from Kwemakame/Kwai noticed
considerably more water.
“we don’t know exactly what you’ve been doing up
there in Dindira, but it helped a lot.
We didn’t experience having so much water for
many years. Even in the last dry months we had
water all day long”.

71. Dry season yield monitoring
year month yield (l/sec)
2009 Oktober 0.15
2010 November 0.42
2011 September 0.31
2012 November 0.25
-------------------------------------------------
average before the project: 0.30
2013 November 0.70
2014 29/10/2014 0.90
Observed yield of the Dindira Water
Catchment at the end of the dry season
•Yield increased from 0.30 to 0.80 l/sec
•Kwemakame/Kwai requires is 1.0 l/sec
•Kidandi source gives 0.15
• The required water is now available

72. CONCLUSIONS
• Rainwater harvesting and infiltration by
artificial recharge can significantly improve
the water supply
• Water conservation by closing intakes during the rain
season adds a positive effect as well.
• Proper maintenance and operation is a first
requirement for sustainability
• The community, Chamavita and Pangani Basin Water
were deeply involved in this project and gained a lot of
new knowledge on how to improve the ‘spring’ water
catchment system. They are eager to replicate and
upscale the concept to similar water schemes.

73. CHALLENGES AND LESSONS LEARNED
• Assessment of runoff (where, how much)
• Proper operation and maintenance is crucial
• Re-use Silts that are trapped in the dam
• Construction of earth dams on steep slopes.
• To replicate this in other areas, you first need to
understand the groundwater system
• For this understanding hydrological monitoring
is required (yields, groundwater levels, rainfall,
…)
•
Other (technical) lessons learned.
• It is extremely difficult to manage extensive

74. Other (technical) lessons learned.
• It is extremely difficult to manage extensive hydrological monitoring
without experts on the ground, who are continuously analysing and
checking the quality of the data collection.
• Know your runoff in the early project stages. It is important to know
how much runoff water is there to catch. In our case the runoff was
less than expected. Runoff tracks must be identified (and quantified)
beforehand during heavy rains.
• Rainfall variability is high. For quantification purposes it is essential
to have multiple rain stations over the catchment, measuring not only
daily totals but rainfall intensity as well.
• The results show that rationing is effective, saving additional water
for the dry season. In particular think of closing the highest intakes
during the rain season ( starting with nr.2)
• How much and how fast will the infiltration water flow out at the
source/intake: a set of ‘design rules’ is required.
• Proper operation and maintenance of the facility and its
surroundings is required to assure that it will continue supplying.

75. Water quality
• Indication of raised Nitrate contents by
agriculture
• Water source protection must be addressed
• Artificial recharge preferably in the forest area,
lakini….

76. Asante

77. MASWALI ?

86. The other pilot, pilot nr.2

87. runoff
source pipe trench
new intake
storage
(valley) dam
Pilot 2
DESIGN

88. Pilot 2 area

89. Valley dam location

90. construction

91. Auger drilling

92. Auger drilling

93. New intake

94. Auger drilling

95. outlet pipe trench

97. • Unfortunately the new intake has much
less water than expected
• Permanent Groundwater seepage flow to
the dam 5000 lita every day!
• This water is treated by a SSF (Slow Sand
Filter)

98. 4000 l/day5000 l/day

99. • Very unfortunately the new intake has
much less water than expected due to bad
siting (by us).
• The aquifer is largely blocked by clays
• In stead the water is seeping to the
reservoir (4000 l/day)
• Water is treated by a Slow Sand Filter

100. Slow sand filter

101. MASWALI ?