IlUNITED REPUBLIC OF TANZANIA
IATIONAL DEVELOPMENT AGENCY DANIDA
824TZ.IR 85
IMPLEMENTATION OFWATER MASTER PLANS FORIRINGA, RUVUMA AND MBEYA REGIONS
HYDROLOGY - LOW FLOW GAUGINGS 1984
CARL BRO • COWiCONSULT • KAMPSAX - KRLJGER «CCKK
IUNITED REPUBLIC OF TANZANIADANISH INTERNATIONAL DEVELOPMENT AGENCY DANIDA
IMPLEMENTATION OFWATER MASTER PLANS FORIRINGA, RUVUMA AND MBEYA REGIONS
HYDROLOGY - LOW FLOW GAUGINGS 1984
! T. i1 -:i- i u / O
L.G:
0
LIBRARY, INTERNA n:-NA-,.
-; j )] G.-.f. 1 4 1 / 1 4
CARL BRO • COWICONSULT • KAMPSAX - KRLJGER «CCKK
III
LOW FLOW STUDIES IN IRINGA, MBEYA AND RUVUMA REGIONS, TANZANIA
III
IIIIIIIIIIIIII
TABLE OF CONTENTSPage
1. INTRODUCTION 1
2. DESCRIPTION OF FIELD WORK 2m 2.1 Low Flow Measurements 2
2.2 Network Station Visits 3
3. DATA ANALYSES 4
4. VILLAGE WATER DEMAND VERSUS AVAILABILITY 16
5. CORRELATION ANALYSIS 29
6. CONCLUSION AND RECOMMENDATIONS 32
APPENDIX 1
I
IIIIIIIIIIIIIIIIIII
1. INTRODUCTION
The aim of the low flow study is to provide the best possible estimates
of the 10-year minimum flows at the selected sources of the village
water supply schemes. Such estimates will form the basis for the final
design of the individual water supplies and for additional source
investigations where selected sources do not have sufficient yields.
The low flow measurement programme was conducted during the months of
September, October and November 1984. Two measurements were made at
most of the selected sites with approximately one month lag-time
between them. At some sites it was not possible to make the second
measurement owing to unsually early and heavy rainfall.
The sources, at which the flows were measured, were selected according
to the procedure outlined in the Working Paper "Minimum Flow Assessment
at Village Level", September 1984, Appendix 1 of this report.
Questionnaires were filled in for each of the measured sites, and the
analyses and conclusions from these are detailed in this report.
In addition, a correlation analysis of annual minimum discharges at the
permanent hydrological stations in the same areas has been performed.
The field work in the three regions of Tanzania was carried out in
close cooperation with the respective MAJI officers who provided help-
ful and capable field teams.
IIIIIIIIIIIIIIIIIIIII
2. DESCRIPTION OF FIELD WORK
The data needed for the low flow study necessitated two different field
activities, a) low flow measurements at 132 sources for future water
supplies, and b) evaluation of the permanent hydrological network rele-
vant for the study within the project area.
2.1 Low Flow Measurements
Two field teams in each region were in charge of conducting discharge
measurements at pre-selected sites, see Appendix 1 "Working Paper,
September 1984 for list of villages. Each team was equipped with a
Landrover and put in charge of half the number of districts in their
region.
The field teams visited between one and three sites a day and made
discharge measurements by pygmy current meter on large and fairly large
streams, by V-notch on smaller streams and by bucket on very small
streams. The results were entered in a questionnaire where also
answers to questions about the stream and the village were noted.
These questionnaires have formed the basis for the following analyses.
The field teams and their work was checked at random times by the
hydrologists and they have proven to be of very high quality.
The measurements were conducted at the end of the dry season in order
to measure the baseflow (groundwater flow) unaffected by rainfall.
The measurements were made with a timelag of approximately one month to
enable calculation of the rate of depletion by means of which the
absolute low flow of 1984 is estimated.
At some sites it was only possible to make one measurement and at other
sites the second measurement had been affected by rain.
Two sites were not visited at all, and no estimates of low flow will be
made at these sites.
IIIIIIIIII1IIIIIIIIII
2.2 Network Station Visits
The estimated low flow will be related to the lowest flow obtained in
1984 from the permanent hydrological network stations. To this end,
visits to a number of gauging stations were necessary to have a picture
of the reliability of the data collected from these.
10-year minimum flows have been calculated for 12 stations during the
Water Mater Flan of Iringa, Mbeya and Ruvuma, see Table 1, and these
flows will be used in the following analyses. Nine of the above
mentioned twelve stations were visited by the hydrologist and one of
the remaining three stations was closed because of road construction.
Altogether 19 of the most reliable stations in the network were visited
in order to assess the reliability of the data - and out of these 18
stations were found to be in a satisfactory condition.
The water levels from a number of stations have been collected and
converted to discharges of which the lowest for each station is found.
The ratio of the minimum flow of 1984 and the 10-year minimum will
then be used to scale the minimum flow of the measured streams in order
to find its 10-year minimum.
Table 1 - 10-year minimum flows at selected hydrological stations
Station River Areakm*
10-year minimuml/s/km* 1/s
1KA 22
1KA 37A
1KA 32A
IRC 8A
3A 8
IRC 5A
1KA 7A
IRC 3A
3B 15
1RB 2
1KB 19
1KB 18B
IRC 2A
Mtitu
Lukosi
Lt Ruaha
Kiwira
Myovisi
Kiwira
Chimala
Mbaka
Mtembwa
Ruhuhu
Hagafiro
Ruhudji
Kiwira
445
2890
759
655
152
217
167
645
8000
2220
153
410
1660
2.5
2.8
0.3
8.3
1.6
9.5
1.0
3.9
0.01
6.67
3.5
3.5
5.4
1,130
8,092
228
5,436
243
2,062
167
2,540
80
14,830
536
1,435
8,964
IIIIIIIIIIIIIIIIIIIII
3. DATA ANALYSES
The questionnaires from each of the selected water supply sources have
been analysed and a recession constant calculated, where possible. The
recession constants are calculated using the equation
Q2 - Ql x .
where
Ql is the discharge at the time ti
0.2 is the discharge at the time t2
k is the recession constant varying for each catchment
The recession constants for the selected water supply sources are shown
in Table 2.
The lowest discharge for 1984 for 11 out of the 12 selected hydrologi-
cal stations plus that of station 1KB 18B was found. The number of
days (t2 - ti) from the latest low flow measurement (Qj) to the lowest
discharge at the nearest hydrological station was then found and used
in the above equation to find Q2 (the absolute lowest flow for 1984 at
the sources).
The station 1KB 18B was selected as the closest station to station
1KB 19, which has a calculated 10-year minimum, but has been closed
because of the Makambako to Songea road construction. The 10-year
minimum of 1KB 18B has been estimated by multiplying the 10-year mini-
mum specific yield of 1KB 19 by the catchment area of 1KB 18B. The
10-year minima are shown in Table 1.
At each hydrological station the ratio of the 10-year minimum
(QlO-year min' a n d t n e lowest 1984 discharge (Qnin 1984) is found and
used to scale the calculated 1984 minima of the sources (qm£n 1984)
near to it, in order to estimate their 10-year minima (qio-year
IIII
II
II1
IIII
III
Table 2 - Recession constants
Villagename
Iringa
Ismani Group
Tungamalenga
Nyamahana
Ilula
Tanangozi
Magubike
Ikungve
Mfukulembe
Idonda
Ilula Itunda
Image
Mtitu
Mafuruto
Ibwnu
Mufindi
Maduma *
Mbalamaziwa
Nyakipanbo
Igomaa
Kiliminzowo
Wambi
Siombe
Ujindile
Boimanda
Usalule
Horonga
Makete
Bulongva
Lupalilo
Ikonda
Macamba
Iwawa
Kisinga
Ihanga
Ukwama
Masisewe
Mbalatse
Igolwa
Ukange
12
l2
12
Date
84.10.03.84.09.24.
84.10.02.
84.10.02.
84.09.26.
84.09.28.34.09.23.
84.10.01.
84.10.04.
34.10.05.
84.10.09.
84.09.26.
84.09.29.
84.11.07.
34.10.06.
84.10.29.
84.10.03.
84.09.27.
34.09.26.
34.10.09.
84.09.25.
84.09.29.
84.09.28.
84.09.29.
84.10.01.
84.10.17.
84.10.16.
84.10.01.
84.10.13.
84.10.16.34.10.02.
34.10.01.
84.10.15.
84.10.02.
34.10.02.
84.10.13.
84.10.15.
84.10.13.
1stmaasurem.
L/S-
88.0
7.7
204.0
159.0
19.2
19.18.2
34.7
0.62
1.98
6.05
10.2
23.0
190.1
5.5
8.4
0.35
168.2
53.4
5.2
8.2
156.0
9.9
16.9
1.8
0.31
4.5
0.75.4
10.7
2.9
1.5
0.35
0.65
0.14
1.37
Date
84.10.29.84.10.26.
84.10.31.
84.11.05.
84.10.27.
84.11.02.84.11.02.
84.11.05.
84.11.06.
84.11.01.
84.10.30.
84.10.27.
84.11.03.
84.10.29.
84.10.29.
34.10.29.
"84.10.27.
84.10.30.
84.10.31.
84.10.30.
84.11.02.
84.11.05.
85.11.05
34.11.04.
84.11.07.
84.11.06.34.11.06.
84.11.05.
84.11.04.
34.11.04.
84.11.03.
84.11.02.
84.11.03.
84.11.03.
2ndmeasurem.L/S
31.28.5
110.6
155.0
13.7
18.88.1
32.3
0.26
1.95
10.85
4.36
40.6
7.9
0.33
106.4
41.4
2.65
7.2
154.0
16.2
38.7
1.5
0.25
3.3
1.954.64
10.7
2.2
1.7
0.16
0.7
0.22
1.16'
RecessionConstantdays-1
0.0031
0.0202
0.0007
0.0105
0.00040.0002
0.0019
0.0252
0.0005
0.0262
0.0021
0.0013
0.0216
0.0077
0.0206
0.0042
0.0004
0.0092
0.0061
0.0165
0.0044
0.0131
0.0234
0.0075
Remarks
never dries
never dries
never dries
never dries
discharge toolarge to measure
never dries
dry
never dries
never dries
never dries
never dries
never dries
never dries
never dries
i Source has not been measured
IIIIIII1III1IIIIIIIII
Table 2 - Continued
Villagename
Ludewa
Mawengi
Itundu
Madunda
Madilu
Lugarawa
Luilo
Mboil
Mbozi Uest
Myovisi
Vwawa
Kacete
Ihanda
Isandula
Senjele
Heiya
Vwawa Township
Ileje
Iioko
Sheyo
I tale
Mbeya
Ilongo
Mbuyuni
Utengule
Ikhoho
Ihombe
Uyole
Iwindi
Isuto
Itimba
Rujewa
Ijumbi
Isangala
12
12
12
12
12
123
12
Date
84.10.19.
84.10.17.84.10.17.
84.10.19.84.10.17.
84.10.15.84.1L.12.
84.10.15.
84.10.22.84.10.22.
84.10.05.
34.10.10.
84.10.07.
34.10.04.
84.10.09.
84.10.06.84.10.06.
84.10.01.
84.10.11.
84.10.11.
84.10.14.
84.1071*3 :
84.10.12.84.10.12.84.10.12.
84.10.20.
84.10.20.
84.10.21.
84.10.22.
84.09.28.
84.10.22.
84.09.28.34.09.28.
84.10.18.
84.10.19.
84.10.21.
84.10.26.
34.10.18.
Iscmeasures.
L/S
1.8
0.70.22
0.500.46
0.370.17
0.43
0.601.6
834.0
24.5
10.8
5.6
0.4
1.7212.2
80.2
168.0
13.5
13.6
6.0
13.512.2
168.0
100.0
592.0
134.0
22.8
13.5
6.3
24.945.1
9.6
83.0
2810.0
27.0
Data
84.11.15.
84.11.13.84.11.13.
84.11.15.84.11.15.
84.11.12.
84.11.12.
84.11.14.84.U.14.
84.11.02.
84.11.01.
84.U.01.
84.11.OS.
84.11.03.84.11.03.
84.10.30.
84.11.08.
84.U.13.
84.U.16.
84.11.13.
84.11.10.
84.10.30.
84.11.11.
34.10.30.84.10.30.
84.11.10.
84.11.15.
34.11.12.
2ndmeasurem.
L/S
1.6
0.70.16
0.550.38
0.41
0.41
0.151.48
503.0
22.95
9.5
7.6
1.6626.8
77.7
180.0
29.5
177.0
905.0
118.0
12.1
11.9
5.7
27.852.0
68.8
2514.0
30.3
RecessionConstantdays"1
0.0037
0.0113
0.0063
0
0.05610.0034
0.0173
0.0029
0.0050
0.0013
0.0011
Village posi-tion tfrong, allvillages onwatershed
0.0183
0.0312
0.0039
0.0053
0.0081
0.0043
Remarks
never dries
never dries
never driesnever dries
never dries
never dries
other sourceshould be found
never dries
never drit»
never dries
never dries
never drit*
never driesnever driesnever dries
never dries
never dries
never driesnever dries
never dries
never dries
new sourceshould be foundsource runs dry
IIIIIII1III1I1IIIIIII
Table 2 - Continued
Villagename
Chunya
Mtanila
Ngvala
Mkwajuni/Mwambani
Maleza
NamkuXwe
Ifyenkenya
Rungwe
Nsigara
Kasiabone
N'daga
Kanyelele
Mgopyolo
Lyenje
Ndicu
Kyela
Ngana
Ngamanga
Sinyang»
Songea
Libango
Namabcngo
Mpitimbi
Muhukuru
Magagura 12
Ngahokora
Matimira
Nakahuga
Paramiho *
Lipokel»
Mbiagawhalule
Limamu
Haaga
Mlilayoyo
Mbimbi
Kilangalanga
Nguindé
«dvema
Namatuhi
Njalaoataca
Namangol»
Lilondo 1I
Dace
84.10.17.
84.10.19.
84.10.22.
84.10.20.
84.10.26.
84.10.24.
84.10.09.
84.10.10.
84.09.29.
84.10.09.
84.10.11.
84.10.11.
84.10.08.
84.10.04.
84.10.06.
84.10.08.
84.10.19.
84.11.29.
84.10.14.
84.10.14.
84.10.11.84.10.11.
84.10.10.
84.10.04.
84.10.05.
84.10.09.
84.10.12.
84.10.17.
84.11.01.
84.10.05.
84,10.16.
84.10.17.
34.10.16.
84.10.06.
84.10.13.
84.10.17.
84.10.18.
34.10.11.84.10.11.
1stmaasurem.
L/S
16.3
2.77
0.96
638.6
9.24
769.0
3.3
5.0
13.7
0.065
3.35
32.1
164.0
16.5
24.9
4.25
0.46
0.76
0.100.04
0.13
1.7
0.21
0.31
0.12
7.9
5.4
0.6
0.45
0.43
0.2
0.13
1.5
2.6
1.21
0.480.69
•Dace
84.11.13.
84.11.19.
84.11.17.
84.11.15.
84.11.05.
84.11.05.
84.10.31.
84.11.07.
84.11.08.
84.11.07.
84.11.07.
34.11.03.
84.11.05.
84.11.03.
84.11.27.
84.11.06.84.11.06.
84.11.07.
84.11.OS.
84.11.27.
84.11.07.
84.11.28.
84.11.30.
84.11.29.
84.11.28.
84.11.29.
84.11.29.
84.11.28.
2ndmass urea.
L/S
9.2
2.4
0.86
1557.0
9.4
320.0
2.05
3.2
22.8
0.05
2.34
30.9
80.0
9.8
31.6
0.300.05
0.08
0.19
0.25
0.07
3.2
0.33
0.58
1.0
0.2
4.1
1.11
RecessionConstantdays-1
0.0218
0.00S3
0.0038
0.0332
0.0140
0.0154
0.0093
0.0115
0.0012
0.0229
0.0193
0.0158
0.0032
0.0043
0.0182
0.0212
0.0106
0.0021
Remarks
dry
dry
never dries
never dries
never dries
never dries
never dries
never dries
never dries
never driesnever dries
never dries
runs dry
never dries
never drie*
never dries
never dries
never dries
never dries
never driesnever dries
X Source has not been measured
IIIIII11IIIIIII1I1III
Table 2 - Continued.
Villagename
Mbinga
I, undo
Mango
Ngindo
Liteabo
Ndumbi
(Cindimba chini
Kindimba juu
Linda
Kihangi
Silo
Wuklro
Maheng*
Hyangayanga
Miyao
Sepukila
Malindindo
MikaUnga
Mpepai
Mbaaba bay
Mapilipili Liwihi
Nangombo
Tunduru
Mateoanga
Nandembo
Machemba
Naluwale
Asani
Kindamba
Mi»yaje
Njanga
Ma rumba
Dace
84.11.14.
84.11.14.
84.11.15.
B4.10.17.
84.11.12.
34.10.13.
84.10.13.
84.10.22.
84.10.22.
84.10.24.
34.10.17.
84.10.17.
84.10.20.
84.10.25.
84.10.18.
84.10.16.
84.10.16.
84.10*. 21.
84.10.26.
84.10.24.
84.10.26.
84.10.30.
84.10.28.
84.10.27.
84.10.27.
34.10.23.
84.10.30.
84.10.24.
84.10.25.
84.10.25.
1stmeasures».
L/S
7.2
3.3
444.0
6.9
0.07
2.7
0.5
1.3
0.09
0.32
1.7
0.43
1.1
13.3
0.07
4.4
6.7
537.0
0.006
S65.O
6.6
2.1
2.1
3.7
17.9
4.5
1.1
32.3
0.35
Dace
84.11.20.
84.11.08.
84.11.08.
84.11.26.
84.11.26.
84.11.26.
84.11.20.
84.11.20.
84.11.21.
84.11.21.
84.11.21.
84.11.16.
84.11.26.
84.11.16.
84.11.26.
84.11.13.
84.11.12.
84.11.13.
84.11.08.
84.11.27.
84.11.10.
84.11.10.
84.11.10.
2ndmaasuram.
L/S
6.5
2.2
0.26
2.2
0.06
0.30
1.48
0.10
20.4
3.9
8.0
3210.0
0.002
693.0
6.3
0.21
1.7
2.314.6
2.2
1.3
34.5
0.33
SecessionConstantdays"'-
0.0015
*
0.0081
0.0216
0.0112
0.0020
0.0044
0.0420
0.0031
0.0318
0.0015
0.1272
0.0122
0.0275
0.0121
0.0243
0.0035
Remarks
never dries
never dries
never dries
never dries
never dries
never dries
never dries
never dries
never dries
spring sourcesupply out oforder
never dries
•
never drie*
never dries
II1I1I1IIII1I1IIIIIII
The equation is shown below, and the calculated 10-year minima for the
sources are shown in Table 3.
- QlO-minq 10-year min " <lmin 1984 (r )
^min 1984
For the sources at which only one measurement is valid a recession
constant of 0.0300 has been selected with which to calculate the mini-
mum flow of 1984. This recession constant has been selected on the
safe side in order not to calculate too large a low flow. The calcul-
ated low flow has then been scaled with the ratio of the nearest hydro-
station, see equation above*.
I 10
II
1IIIIIII1IIIIIII
Table 3 10-year minimum flows
VillageName
Iringa
Ismani
Tungamalenga
Nyamahana
Ilula
Tanangozi
Magubike
Ikungwe
Mfukulembe
Idonda
Ilula Itunda
Image
Mtitu
Ibumu
Mufindi
Maduma
Mbalamaziwa
Nyakipambo
Igomaa
Kiliminzowo
Wambi
Njombe
Ujindile
Boimanda
Usalule
Moronga
12
12
Ql
L/S
81.27.7
110.6
155.0
13.7
18.88.1
32.3
0.26
1.95
6.05
4.36
28.0
190.1
5.5
7.9
0.33
106.4
41.4 .
2.65
7.2
154.0
9.9
RecessionConstant
k
0.00310.0300
0.0202
0.0007
0.0105
0.00040.0002
0.0019
0.0252
0.0005
0.0300
0.0262
0.0300
. 0.0300
0.0-300
0.0021
0.0018
0.0216
0.0077
0.0206
0.0042
0.0004
0.0300
Time lag
t
3030
3
10
19
1313
10
9
14
35
19
47
47
16
17
17
17
19
16
15
16
46
Q min 198A
L/S
743.1
104.1
154
11.2
18.78.0
31.7
0.21
1.94
2.12
2.65
6.8
46.4
3.4
7.6
0.32
0.0
73.7
35.8
1.91
6.76
153.0
2.5
10-yearminimum
L/S
34.7
46.9
69.3
5.0
12.0
14.3
0.1
0.9
1.0
1.2
3.1
20.9
1.5
3.4
0.14
0
33.2
16.1
0.9
3.0
68.9
1.1
IIIIIIIIIII1III1IIIII
11
Table 3 Continued
VillageName
Makete
Bulongwa
Lupalilo
Ikonda
Matamba
Iwawa
Kisinga
Ihanga
Ukwaroa
Masisiwe
Mbalatse
Igolwa
Ukange
Ludewa
Mawengi
Itundu
Madunda
Madilu
Lugarawa
Luilo
Mbozi
Mbozi West
Myovisi
Vwawa
12
12
12
12
12
Vwawa Township
Katete
Ihanda
Isandula 12
Ql
L/S
16.9
1.5
0.25
3.3
0.74.64
10.7
2.2
1.7
0.16
0.65
0.14
1.16
1.6
0.70.22
0.500.38
0.370.17
0.41
0.151.48
503.0
24.5
9.5
13.5
5.6
0.4
1.6612.2
RecessionConstant
k
0.0300
0.0092
0.0061
0.0165
0.03000.0044
0.0300
0.0131
0.0300
0.0234
0.0300
0.0300
0.0075
0.0037
0.03000.0300
0.03000.0063
0.03000.0300
0.0300
0.05610.0034
0.0173
0.0300
0.0300
0.0300
0.0300
0.0300
0.03000.0300
Time lag
t
30
10
11
8
309
10
11
11
12
13
12
12
0
22
00
33
3
11
6
7
10
6
13
8
1111
Q min 1984
L/S
6.9
1.4
0.23
2.9
0.34.46
7.93
1.9
1.22
0.12
0.44
0.1
1.06
1.6
0.660.21
0.88
0.49
0.37
0.141.47
453-
19.9
7.0
11.3
3.8
0.3
1.28.8
10-yearminimumL/S
3.1
0.6
0.1
1.3
2.1
3.6
0.9
0.6
0.1
0.2
0.1
0.5
0.7
0.4
0.4
0.2
0.2
0.7
453
19.9
7.0
11.3
3.8
0.3
1.28.8
111I1II1111I111I11111
Table 3 Continued
VillageName
Mbozi
Senjele
Hezya
Ileje
Isoko
Sheyo
Itale 123
Mbeya
Ilongo
Mbuyuni
Utengule
Ikhoho
Ihotnbe
Uyole
Iwindi 12
Isuto
Itimba
Ru j ewa
I^umbi
Isangala
Chunya
Mtanila
Ngwala
Mkwa j uni /Mwam.
Maleza
Namkukwe
Ifyenkenya
Qi
L/S
77.7
168.0
13.6
6.0
13.512.2
168.0
100-0
592.0
118.0
12.1
11.9
5.7
24.945.1
9.6
68.8
2514.0
27.0
9.2
2.4
0.86
638.6
RecessionConstant
k
0.0300
0.0300
0.0300
0.0300
0.03000.03000.0300
0.0300
0.0300
0.0184
0.0312
0.0039
0.0053
0.03000.0300
0.0300
0.0081
0.0043
0.0300
0.0218
0.0053
0.0038
0.0300
Time lag
t
16
6
52
53
545454
33
33
8
13
1919
0
18
26
18
12
14
15
Q min 1984
L/S ,
48.1
140.3
2.86
1.22
2.672.4133.25
37.16
220
102
8.3
11.9
5.7
14.125.5
9.6
68.8
2327
12.4
0
0.0
6.2
2.3
0.82
0.0
407
12
10-yearminimum
L/S
48.1
140.3
2.6
1.1
2.52.230.6
• - —
18.6
110
51
4.1
11.9
5.7
39.6
9.6
68.8
1573
6.2
0
0
4.7
1.7
0.6
0
100
13
1
III
Table 3 Continued
Village Ql Recession Time lag Q min 1984 "10-yearName Constant minimum
L/S k t L/S L/S
Rungwe
Nsigara 9-24
Kasiabone 320.0 0.0332 30
Ndaga 2.05 0.0140 0
Kanyelele 3.2 0.0154 29
Ngopyolo 13.7
Lyenje 0.05 0.0093 33
Nditu 2.34 0.0115 29
Kyela
Ngana 30.9 0.0012 0
Ngamanga 80.0 0.0229 0
Sinyanga 9.8 0.0193 0
Songea
Libango 24.9 0.0063 27
Namabengo 4.25 0.0300 9
Mpitimbi 0.46 0.0300 31
Muhukuru 0.76 0.0300 31
Magagura 1 0.10 0.0300 35
2 0.04 0.0300 35
Ngahokora 0.08 0.0158 36
Matimira . 1.7 0.0300 41
Nakahuga 0.19 0.0032 40
Feramiho
Lipokela 0.25 0.0043 11
Mbingamhalule 0.07 0.0182 8
Limamu 3.2 0.0212 0
Lilondo 1 0.48 0.0300 35
2 0.69 0.0300 35
Hanga 5.4 0.0300 15
Mlilayoyo 0.33 0.0106 0
Mbirabi 0.45 0.0300 30
Kilangalanga 0.43 0.0300 28
Ngwinde 0.20 0.0300 0
9.2118.2
2.05
2.1
13.7
0.037
1.7
30.9
80.0
9.8
21.0
3.24
0.2
0.3
0.10.01
0.5
0.1
0.24
0.05
3.2
0.160.23
3.44
0.33
0.25
0.25
0.20
8.3108.4
1.85
1.9
12.3
0.034
1.6
13
35
..1.0
18.9
2.9
0.2
0.3
0.1
0.1
0.5
0.1
0.2
0.1
2.9
0.4
3.1
0.3
0.2
0.2
0.2
III1IIIIIIIIIIIIIIIII
14
Table 3 Continued
VillageName
Songea
Mdwema
Namatuhi
Njalamatata
Namanguli
Mbinga
Lundo
Mango
Ngindo
Litembo
Ndumbi
Kindimba chini
Kindimba juu
Linda
Kihangi
Silo
Wukiro
Mahenge
Myangayanga
Miyao
Sepukila
Malindindo
Mikalanga
Mpepai
Mbamba Bay
Mapipili Liwihi
Nangombo
Tunduru
Matemanga
Nandembo
Machemba
Naluwale
Ql
L/S
0.13
1.5
2.6
1.11
7.2
3.3
444.0
6.5
0.07
2.2
0.26
1.3
0.06
0.30
1.48
0.10
1.1
13.3
0.07
3.9
6.7
537.0
0.002
565.0
6.3
0.21
1.7
2.3
RecessionConstant
k
0.0300
0.0300
0.0300
0.0021
0.0300
0.0300
0.0300
0.0015
0.0300
0.0081
0.0216
0.0300
0.0112
0.0020
0.0044
0.0420'
0.0300
0.0300
0.0300
0.0031
0.0300
0.0300
0.0318
0.0300
0.0015
0.1272
0.0122
0.0275
Time lag
t
40
32
28
0
0
0
0
0
0
7
7
23
0
0
0
0
25
20
28
0
30
20
0
20
0
2
3
2
Q min 1984
L/S
0.1
0.57
1.12
1.11
7.2
3.3
444.0
6.5
0.07
2.1
0.22
0.65
0.06
0.30
1.48
0.10
0.5
7.30.03
3.9
2.7
295
U .UUZ
310
6.3
0.2
1.64
2.2
"10-yearminimum
L/S
1 0.1
0.5
1.0
1.1
6.5
3.0
400
5.9
0.1
2.1
0.6
0.1
0.30
1.3
0.1
0.4
6.6
0.1
3.5
2.5
265
n iU. I
280
5.7
0.2
1.5
2.0
111111111111111111111
Table 3
VillageName
Tunduru
Amani
Kindamba
Misyaje
Nj enga
Marumba
-
Continued
Ql
L/S
14.6
2.2
1.1
32.3
0.33
RecessionConstant
k
0.0121
0.0243
0.0300
0.0300
0.0035
Time lag
t
7
0
20
20
5
Q min 1984
L/S
13.4
2.2
0.6
17.7
0.32
15
-10-yearminimumL/S
12.1
2.0
0.5
16.0
0.3
IIIIIIIIIIIIIIIIIIIII
16
4. VILLAGE WATER DEMAND VERSUS AVAILABILITY
The village water demand has been calculated during Che Water Master
Plan of Iringa, Mbeya and Ruvuma for each water supply scheme and has
been based on the expected population in the year 2006, multiplied by
the amount of water needed per capita per day. Some of the future
populations seem to have been estimted rather too high, especially for
the arid ares, and it may be advisable to look into this matter. The
populations in question are marked by an asterix in Table 4.
Below is a list of water demands versus availability - from which it
can be seen that 49% of the village water supply schemes measured will
have sufficient water in the year 2006.
In 51% of the schemes the water available is less than what will be
needed, and in these schemes it is very important to locate other
sources with large enough minimum flows, either to supply all the water
needed, or at least enough to supplement the proposed source. Should
this not be possible, then an alternative solution, i.e. shallow wells,
must be considered.
At some sites it has been difficult to measure the water available,
either because of seepage over a large area, or because of water
collects underground, resulting in little or no surface flow. There-
fore, some of the measurements do not reflect the actual amount of
water available. A brief description of each site at which there was a
deficit is therefore needed.
Iringa Region, Iringa District
I lu 1 axj3r oup_ :
Additional sources may be needed to supply the proposed amount of
water. Reconnaissance will be needed.
Ikungwei_Single:
Several streams run through the village, and intakes could be
constructed on one or more of these streams. Measurements on these
streams will determine how many intakes are necessary.
IIIIIIIIIIIIIIIIIIIII
17
Ilula_ItundaA_Single
The measurements were made 100 m upstream of the intake structure, but
even so, it is necessary to provide additional water, which may be
found in nearby streams.
Imagex_Grou2
Since only one measurement was valid here it is difficult to say if the
the amount of water available is too small. Additional measurements
are necessary here.
MtituA_Groug
There may be enough water available here, but since only one measure-
ment is valid it is difficult to say. Additional measurements are
needed to ascertain the quantities of water.
Iringa Region, Mufindi District
Additional sources are necessary in order to supply the needed amount
of water.
This group scheme consists of Nyakipambo, Mtambula and Ihegele vil-
lages, which in the Water Master Plan were single schemes. It would be
an idea either to go back to the original proposal, or to make an addi-
tional intake on Msolwa river if enough water is available here.
A new source has to be found here as the proposed source runs dry.
Several rivers run parallel to the proposed source, and intakes could
be constructed on these when measurements have shown if there is enough
water.
Iringa Region, Njombe District
It is possible that enough water is available here, but as there is
only one valid measurement it is difficult to estimate an exact 10-year
minimum*
IIIIIIIIIIIIIIIIIIIII
18
Iringa Region, Makete District
At all these villages there may be enough water available, but because
only one valid measurement is available it is difficult to be certain,
and additional measurements are recommended.
Several sources run parallel to the proposed source so that intakes
could be established on one or more of these, if additional measure-
ments prove the necessity.
Ikondai_Single
Additional intakes should be possible on sources either parallel to the
proposed village or southeast of the village.
Matamba^Groujj
Additional sources are available in the vicinity to augment the supply
of the existing, but measurements should be made before selecting the
source or sources.
Several additional sources are available in or near the village, but
it may be a problem to get enough head as the village is situated on
the watersheds.
IgolwaA_Single
This village is also located on the watershed so, even though there are
plenty of sources in the vicinity, there is a problem of enough head.
Iringa Region, Ludewa District
MawengiA_Single
Additional sources are needed to supply the necessary amount of water.
A reconnaissance must be made to find a suitable supply.
IIIIIIIIIIIIIIIIIIIII
19
Itundui_Groug
Only the proposed sources were measured, therefore it is very likely
that the three existing intakes can supply the remaining water, only
measurements here can ascertain this.
An additional source should be found in order to supply adequate
amounts of water.
This village is situated on the watershed, so even though plenty of
sources are available, not enough head can be found.
Several additional sources are available here so that intakes on one or
more of them could solve the problems of too little water.
The potential intake sites should be measured and if enough water is
available they should be developed to supplement the proposed sites.
Mbeya Region, Mbeya District
The proposed source runs dry here, therefore another source should be
found if possible, otherwise alternative supply must be sought.
Mbeya Region, Mbozi District
If enough head is available the proposed intake may be moved downstream
to the confluence of the tributary from the south, but measurements
should be made beforehand to make sure this is a viable solution.
IIIIIIIIIIIIIIIIIIIII
20
Mbeya Region, Chunya District
Mtanila^Groug
The proposed year 2006 population seems unrealistic, it is doubtful
that the soil can support such a population expansion. The source runs
dry so that additional sources must be found or shallow wells proposed.
Mwambani/MkwajuniA_Single
Additional sources are needed if the future population has to be
supplied. The population increase does seem unrealistic.
The population increase seems somewhat unrealistic in such a dry area,
but possibly additional sources could be found.
NamkukweA_Single
Additional sources are necessary here as the proposed source runs dry,
shallow wells may be a possibility.
Mbeya Region, Rungwe District
This is a spring source and very difficult to measure accurately.
Seepage around the source was noticed, therefore it is possible that
enough water is available. Additional measurements downstream may give
better results.
Additional intakes will be necessary if the proposed supply shall be
met, and several sources flowing parallel to the proposed source could
supply the required water. Measurements of the amounts will determine
the number of necessary additional intakes.
IIIIIIIIIIIIIIIIIIIII
21
Ruvuma Region, Songea District
The water available is sufficient at present, but cannot supply a
future larger population. However, there are several streams to the
west and south of the village which could supply the required water,
and additional intakes could be constructed there.
Mgitimbix_Grou£
Hpitimbi already has a source that supplies part of the group. Only
one intake was measured although there are two; therefore the yield
should be higher. The measurements are very difficult to perform as
the water is collected by infiltration wells. The supply here is con
sidered sufficient.
Muhukurux_Grou£
It is necessary to locate an additional source here as the supply is
inadequate.
The measurements seem to have been made on another source than the one
proposed. The proposed source could later be developed to supplement
the one MAJI has selected.
This source was measured close to its spring source. The intake could
be moved downstream and then possibly supply the whole village.
The intake site here is very wet but difficult to measure. If the
amount of water proves to be too small there will be several
possibilities of additional sources nearby; however, they will
probably be too low for gravity schemes.
Nakahuga^S ing 1 e
Several additional sources exist to supplment the proposed source but
measurements must take place in order to select the best suited.
IIIIIIIIIIIIIIIIIIIII
22
Peramihoi_Grou2
It was not possible to perform any measurements here as the water is
collected by infiltration galleries» but there seems to be a sufficient
supply.
There is an existing bamboo scheme here, which could be supplemented by
other sources.
The intake could be moved some distance downhill, but will probably
have to be supplemented by other sources.
There are probably no additional sources, therefore other alternatives
must be considered if the proposed amount of water shall be supplied.
The measurements made here are not exact as the area is very swampy,
and therefore the discharge is very difficult to measure. The amount
of water available is considered sufficient.
Additional sources have to be found and measured as the proposed source
cannot meet the demand.
This is a Danida scheme built on MAJI recommendation. In order to
supply the future demand an additional source will have to be found.
The area is very swampy and therefore very difficult to measure, but
the available supply seems to be sufficient.
The measurement here seems unrealistic, and the source ought to yield
more. Additional measurements are recommended.
IIIIII1IIIIIIIIIiIIII
23
Mbinga District
In the mountainous regions of Mbinga District the population tends to
be very scattered within the villages' and to a large extent to inhabit
the watershed areas. As such, it is very difficult to find sources
that originate from higher elevations than the habitation. The area is
supplied by water through thousands of small streams, all perennial and
all with small yields near their spring source. In fact, most houses
have their own little furrow that leads water past their house. It is
therefore a diffcult task to better their supply through one intake, as
parts of the village will always be situated too high for such a
supply. A solution, however, would be to construct several small
intakes and thereby supply the whole village. Villages with such pro-
blems are Linda, Kihangi Manuka, Silo, Wukiro, Mahenge, Myangayanga,
Sepukila and Mapipili Liwihi.
NdumbiA_Single
Plenty of additional sources exist so that adequate water supply should
not be a problem. Measurements should be made before selecting an
additional source.
Measurements are very difficult here as water is collected in an
infiltration well, but the amount is considered sufficient.
Tunduru District
Measurements are difficult here as the intake is situated in a pond.
The supply should be adequate.
An additional source should be found, or an alternative supply
considered for both these supplies.
IIIIII1IIIIIIIIIIIIII
24
Table 4 - Water demand and availability
Village/Group
Iringa District
Ismani Group
Tungamalenga Group
Nyamahana Group
Ilula Group
Tanangozi Group
Magubike Group
Ikungwe, Single
Mfukulembe, Single
Idonda, Single
Ilula Itunda, Single
Image Group
Mafuluto, Single
Mtitu Group
Ibumu
Mufindi District
Maduma, Single
Mbalamaziwa Group
Ihegele
Nyakipambo Group
Mtambula
Igomaa, Single
Kilindnzowo, Single
Wambi Group
Njombe District
Ujindile, Single
Boimanda, Single
Usalule Group
Moronga Group
Makete District
Bulongwa Group
Present/futurepopulation
28,014/42,432
4,529/13,587
4,132/13,830
16,211/40,245
20,615/28,830
5,325/10,465
1,443/ 1,905
1,352/ 1,785
1,334/ 2,588
4,244/ 9,209
8,708/21,989
826/ 2,478
64,782/99,860
1,725/ 3,470
2,912/ 5,824
7,419/14,910
1,295/ 2,590
1,082/ 2,835
2,506/ 5,012
1,291/ 3,382
1,144/ 3,016
13,626/28,245
1,834/ 2,764
541/ 1,278
89,501/195,602
14,962/24,113
17,498/25,481
Waterdemandxa /day
1,051
388
336
1,002
865
259
47
44
64
230
547
61
2,480
86
145
368
259
84
75
949
69
31
5,209
598
629
Wateravailability
m^/day2-year min.
665
14
160
413
2,781
451
18
146
413
Wateravailability
m^/day10-year min.
2.998
4,052
5,988
432
1,037
1,236
9
78
86
104
268
1,000
1,806
130
293
12
0
2,868
1,391
78
259
5,953
95
268
IIIIIIIIIIIIIIIIIIIII
25
Table 4 (cont'd)
Village/Group
Makete District
Lupalilo Group
Ikonda, Single
Matamba Group
Iwawa Group
Kisinga, Single
Xhanga, Single
Ukwama, Single
Masisiwe, Single
Mbalatse, Single
Igolwa, Single
Ukange, Single
Ludewa District
Mawengi, Single
Itundu Group
Madunda, Single
Madilu, Single
Lugarawa, Single
Luilo Group
Mbozi District
Mbosi West Group
Myovisi Group
Vwawa Group
Katete, Single «
Ihanda, Single
Isandula, Single
Senjele, Single
Hezya, Single
Ileje District
Isoko Group
Itale, Single
Present/futurepopulation
Waterdemandm3/day
Wateravailability
mVday2-year min.
Wateravailability
m^/day10-year min.
S
3.306/ 5.290
888/ 1.420
7.001/10.100
5.779/ 9.245
855/ 1.368
1.290/ 1.457
1.327/ 2.672
900/ 1.359
1.744/ 1.970
1,570/ 1.805
1,316/ 1.842
2.371/ 5.572
3.958/ 9.301
1.485/ 3.490
2.504/ 5.884
5.705/13.407
11.198/27.654
28.056/97.669
10.682/23.362
18.037/31.601
2.110/ 8.060
2.959/ 6.421
2.441/ 5.757
2.867/ 6.221
2:436/ 5.286
5.140/ 9.012
3.187/ 6.690
13135
250
273
34
36
66
33
49
45
46
139
232
87
147
355
689
2.432
580
1.042
201
160
143
155
132
224
167
80
14
172
278
80
14
26
14
66
92
54
54
26
26
97
40
347
52
9
112
181
311
78
52
9
17
9
43
60
35
35
17
17
63
6.912
1.719
1.581
328
26
864
4.156
12.122
225
3.050
1III1IIII
IIIIIIIIIII
26
Table 4 (cont'd)
Village/Group
Ileje District
Sheyo, Single
Mbeya District
Ilongo Group
Mbuyuni Group
Utengule Group
Ikhoho, Single
Ihombe Group
Uyole Group
Iwindi Group
Isuto Group
Itimba, Single
Rujewa Group
Ijumbi Group
Isangala Group
Chunya District
Htanila Group
Ngwala, Single
Mkwajuni, Single
Mwambani, Single
Maleza, Single S
Namkukwe, Single
Ifyenkenya Group
Rungwe District
Nsigara Group
Kasiabone, Single
Ndaga Group
Kanyelele Group
Ngopyolo Group
Lyenje, Single
Nditu, Single
Present/futurepopulation
.....
1.632/ 3.084
14.027/46.244
11.009/36.485
7.703/30.658
1.262/ 1.767
4.555/ 6.211
9.618/13.271
13.191/18.256
8.342/11.250
1.605/ 2.188
20.981/86.470
4.843/19.730
3.485/ 5.151
7.007/34.964
. 1.039/ 2.881
5.032/ 15.126
2.199/ 6.597
3.680/11.040
4.342/10.464
2.900/ 3.354
1.232/ 1.626
6.273/10.532
4.730/ 5.020
6.797/ 8.973
1.058/ 1.442
2.400/ 3.168
Waterdemandm^/day
77
1.152
907
766
44
144
332
422
279
54
2.779
522
128
874
72
377
164
275
260
83
24
269
125
224
36
79
Wateravailability
mVday2-year min.
226
80
245
5
Wateravailability
m^/day10-year min.
95
1.607
9.504
4.406
354
1.028
492
3.421
829
5.944
201.053
536
0
0
406
147
52
0
8.640
717
9.366
159
164
1.063
3
138
IIIIII1II1IIII1IIIIII
27
Table 4 (cont'd)
Village/Group
Kyela District
Ngana Group
Ngamanga Group
Sinyanga Group
Songea District
Libango Group
Namabengo Group
Mpitimbi Group
Muhukuru Group
Magagura, Single
Ngahokora, Single
Matimira, Single
Peramiho Group
Lipokela Group
Mbingamhalule, Single
Limamu, Single
Lilondo., Single
Hanga, Single
Mlilayoyo, Single
Mbimbi, Single
Ngwinde, Single
Mdwemba, Single
Namatuhi, Single
Njalamatata Group
Namangole Group
Kilangalanga, Single
Nakahuga, Single
Mbinga District
Lundo Group
Mango Group
Ngindo, Single
Litembo, Single
Present/futurepopulation
25.127/34.740
12.747/19.3367.325/10.314
12.863/22.730
5.368/13.130
4.167/10.430
6.192/14.8602.531/ 6.190
1.629/ 3.9902.591/ 6.560
4.555/ 6.882
2.402/ 7.162
2.180/ 5.700
2.035/ 5.3301.747/ 4.280
2.426/ 6.1401.032/ 2.520
1.379/ 3.2001.039/ 2.750
719/ 1.8801.331/ 3.260
7.679/18.780
3.649/ 9.1201.370/ 3.3501.527/ 3.740
2.721/ 3.7755.474/ 8.300
573/ 1.925
2.784/ 6.640
WaterdemandnrVday
861
479
255
566
327
260
370
154
99
163
149
117
142
133
106
153
62
79
68
46
81
467
227
83
93
93
206
48
165
Wateravailabili ty
m-Vday2-year min.
386
26
40
14
14
66
26
14
54
40
26
26
14
66
132
146
26
14
Wateravailabili ty
m^/day10-year min.
1.1233.024
346
1.633
251
17
26
9
9
43
17
9
268
35
268
26
17
17
9
43
86
95
17
9
562
259
34.560
510
1IIIIIIIIII1I1III1III
28
Table 4 Ccont'd)
Village/Group
Mbinga District
Ndumbi, Single
Kindimba chini/juu,S in g te
Linda, Single
Kihangi Mahuka, Single
Silo, Single
Wukiro, Single
Mahenge, Single
Myangayanga Group
Miyao Group
Sepukila, Single
Malindindo, Single
Mikalanga, Single
Mpepai, Single
Mbanba Bay Group
Mapipili Liwihi, Single
Nangombo, Single
Tunduru District
Matemanga Group
Nandembo, Single
Machemba Group
Naluwale Group
Amani Group
Kindamba, Single
Misyaje, Single
Njenga, Single
Ma rumba Group
Present/futurepopulation
2.518/
1.721/
2.044/
1.607/
2.256/
2.720/
1.579/
3.700
3.320
5.212
4.100
4.855
6.490
3.770
6.595/15.960
4.364/11.570
1.569/
2.053/
2.294/
3.000/
5.742/
2.455/
1.770/
4.625/
2.873/
3.938/
1.415/
3.781/
560/
1.183/
1.625/
4.020/
3.190
5.235
5.850
7.150
8.620
6.260
2,650
8.100
6.790
6.970
2.560
9.380
1.000
2.700
3.900
8.139
Waterdemandm^/day
92
82
130
102
121
162
94
397
288_
79
130
146
178
214
156
66
200
169
172
63
232
24
67
97
202
Wateravailability
m^/day2-year min.
14
80
14
42
172
14
54
14
11
26
200
67
40
Wateravailability
nH/day10-year min.
9
181
52
9
27
112
9
35
570
9
302
216
22.896
9
24.192
492
17
130
173
1.045
173
43
1.382
26
IIIIIIIII1IIIIIIIIIII
5.
WA32Anwnarg*
29
CORRELATION ANALYSES
In areas with similar hydrological and geological charactistics the
annual minimum flows from the hydromet stations have been correlated.
Within a selected area a period was chosen in which all stations had
flow data, the annual minima were then found, and correlation between
pairs of stations conducted as shown below.
1KA2A
mV* r.O,7S1 r-OTtt
1KA2MV
1KA21*nf/%
Figure 1 - Correlation of annual minimum flows for hydromet.
stations on Lt Ruaha upstream of Iringa
Correlation between the following stations during the period 1958-79
were performed.
Table 5 - Correlation coefficients of annual minimum flows at hydromet.
stations on Lt Ruaha river upstream of Iringa
1KA 22 1KA 39A 1KA 2A 1KA 32A
1KA 21A
1KA 22
1KA 39A
1KA 2A
0,564 0,781
0,734
- •
-
0,763
0,840
0,888—
0,731
0,610
0,921
0,840
1II11IIII1I11IIIIIIII
30
N
Figure 2 - Hydromet. station on Lt Ruaha river system upstream of
Iringa
Table 6 - Correlation coefficients of annual minimum flows at hydromet,
stations in the Rungwe, Kyela area
IRC 5A IRC 3A IRC 2A
IRC 8A
IRC 5A
IRC 3A
0,692 0,090
0,239-
0,456
0,209
0,517
Table 7 - Correlation coefficients of annual minimum flows at hydromet,
stations in the Mbeya, Myovisi area
3A 14A 3A 6 3A 7A
3A 8
3 A 14A
3A 6
0.01 0.65
0.07
0.41
0.10
0.43
IIIIIIfIIII1IIIIIIIII
31
The recession constants of a river have in earlier studies, i.e. the
Water Master Plan of Iringa, Mbeya and Ruvuma shown to vary little from
year to year.
The analogue assumption would then be that the average recession
constant at a homogenous area varies little from year to year. If this
could be verified by spotchecks during a couple of dry seasons it would
be possible to make only one gauging at the ungauged village sources,
and with the date of the gauging and the date of the absolute minimum
flow at a nearby hydrostation the minimum flow that year could be
calculated, and hence the 10-year minimum of that particular village
source. A greater number of village sources within such areas could be
analysed every season by this method.
Correlation analyses have been conducted in the Rungwe, Kyela area,
the Myovisi, Mbeya area and Little Ruaha upstream of Iringa. It has
not been possible to identify any other areas in which such correlation
would be possible, since in all other areas the topographical and
hydrological characteristics vary greatly.
The Rungwe, Kyela area does not seem to have a very good correlation
- as shown in Table 6 - nor does the Myovisi, Mbeya area as seen from
Table 7; however, the Little Ruaha area upstream of Iringa shows very
good correlation.
In the Lt. Ruaha area only a few of the sources need to be measured;
it can therefore not be recommended that average recession constants be
used in any of the areas of the three regions.
IIIIIIIIII1IIIIIIIIII
32
CONCLUSIONS AND RECOMMENDATIONS
A number of sources, as seen from Table 4, cannot provide the water
which will be needed in the year 2006, and at many locations new or
additional sources have to be found. In Mbeya 8 sources do not provide
enough water, in Iringa 26 and in Ruvuma 33 sources have too small
yields.
This is based on the comparison of the projected water demand in the
year 2006 and the minimum flow statistically expected to occur once in
10 years. It is however important to consider that both a projected
demand and the 10-year minimum flow are parameters which may have a
considerable inherent uncertainty.
The projections of population figures are based on generalized assump-
tions about growth rates which may or may not apply to the particular
village. The 10-year minimum flow is based on various assumptions
about similarity between the behaviour of the stream under investiga-
tion and a larger stream in the vicinity. Thus, we recommend that the
following considerations are applied before rejecting a source not
meeting the demand criteria of year 2006.
- Has the past trends in the village development confirmed the earlier
population projections?
- What is the consequence of rejecting a source, that is, can
additional or alternative sources be developed and at which cost?
- If the 10-year criterion is not met, does the source meet a 5-year
criterion or a 2-year criterion, see Table 8), and what are the
consequences in terms of reduced availability of water for the
villager. Can such a reduction be considered acceptable when com-
pared to the cost of developing either an alternative source or an
additional source. This question also relates to the problem of
whether a traditional source may be acceptable during a period of
deficiency.
III1IIIIIIII1I
33
IIIIII
Table 8 - Villages with too little water in the year 2006
2-year minimum 10-year minimum
Iringa 21 26
Mbeya 8 8
Ruvuma 29 33
Of the 132 measured sources 67 have shown not to have sufficient water
for the future populations in the year 2006. It is therefore highly
recommended that another low flow programme be conducted during the dry
season of 1985. This low flow programme should cover 26 sources In
Iringa Region, 8 sources in Mbeya Region and 33 sources in Ruvuma
Region as recommended in Chapter 4, and should start early September in
order to be completed before the rains start. A proposed time-schedule
is shown below in Fig. 3.
The sources where not enough water was available can be grouped into
two categories:
Category 1: Sources with insufficient water based on two measurements
in 1984.
Category 2: Sources with insufficient water based on one measurement
in 1984 and an assumed recession constant (safe side).
The recommended low flow programme for 1985 would then comprise two
programmes:
*
Programme for category 1: Measurements at additional/alternative
sources
Programme for category 2: Measurements at proposed sources to verify
the minimum flow and if necessary
measurements at additional/alternative
sources.
The village water supply sources under programme 2 are not considered
to be many.
IIIIIIIIIIIIIIIIIIIII
WORKING PAPER
MINIMUM FLOW ASSESSMENT
AT VILLAGE LEVEL
SEPTEMBER 1984
DANIDA - CCKK
IIIIIIIIIIIIIIIIIIIII
WORKING PAPER
MINIMUM FLOW ASSESSMENT AT VILLAGE LEVEL
1. INTRODUCTION
During the Water Master Plan, hydrological investigations were aimedat two different main goals. These were t
to establish the regional hydrological regimecomprising precipitation, evaporation, runoffand the distribution of these parameters in timeand space.
to establish estimates for minimum flow at sourcesnear the villages to suit the planning of thewater supply schemes.
The estimates of minimum flows had to be based on single measurementscarried out during village visits* These were then compared on aregional basis and included in the planning procedure*
It was, however, clear that before actual construction should takeplace there would bê a number of cases where the accuracy of theplanning estimates would not be sufficient and where additional sourceinvestigations would have to be made.
The aim of the present working paper is thus to outline the principlesfor selection of village sources for additional measurements, to presentthe selcted villages and to describe the method of measurement and analysis.
2. SELECTION OF SOURCES FOR ADDITIONAL MEASUREMENTS
2.1 Hydrological zoning
The water master plan results comprised I.a.a map of hydrological zones from which a firstestimate of 10 - year TMtrftmim flows can becalculated for small catchments. (Drg. No. 6Box II 10-year minimum runoff in 1/s/knr). Ingeneral these zones and derived estimates wouldbe more reliable as regards zone 3 and 4 thanas regards zone 1 and 2*
Screening from a purely hydrological point of viewhas thus been performed In the following ways
- if village source yields inzone 1 or 2 are below4 times the estimated demand these sources areincluded in the preliminary list of village sourcesfor additional measurements.
if village source yields in zone 3 or 4 are below 2 timesthe estimated demand these sources are included in thepreliminary list of village sources for additional measurements.
2.2 Construction Programme
The three year rolling construction programme Has been studiedand all included schemes with surface water sources has beenselected for additional measurements unless a relatively largestream with well established dry-season flow is the source.
2.3 Priority Programme
The priority programme of 633 villages has been considered.No single village Is included for additional source assessmentunless it is included in the priority programme. In the sameway, no group scheme has been included for additional measurementunless it comprises a reasonable number of priority schemes. •
2.4 Scheme Type
Villages for which conventional pumping has been the only feasiblesolution Indicated in the Master Plan have not been included, asthe implementation of such schemes will be defered to some futuredate.
2.5 Results of screening procedure
The results in terms of village sources to be assessed in moredetail are given as a list ( Appendix 2.1, 2.2 and 2.3 )•The number of villages /group schemes are as follows :
No. of schemes for additional measurements
IRINGA 41
RUVUMA 52MBEYA 39
TOTAL 132
IIIIIIIIIIIIIIIIIIIII
3. MEASUREMENTS OF DISCHARGE
3.1 Equipment
The measurements of discharge will all be carried out at relativelysmall streams* Three types of equipment are envisaged to besufficient for these measurements which are expected mainly to bein the range of 1 - 50 1/s. The field teams will be equipped with:
t- V-notch (90°)
calibrated bucket and stopwatch
- micro-propeller (OTT-meter)
The V-notch is .manufactured for the purpose, buckets calibratedand the micropropellers are available at the regional hydrologicaloffices to «here they were handed over by the end of the MasterPlan Phase.
3.2 Staffing
The central Maji authorities (Mr. W. Balai le ) hâve been informedabout the programming of the activities and have in turn requestedthe regional hydrologists'.to make available two field teams ineach region. The activities of these field teams will be supervisedby the CCKK-hydrologist. Instructions and a form to be filled infor each source have been prepared ( see Appendix 3.1).
4. PRINCIPLES OF ANALYSIS
4.1 General
The basic idea is to carry out two spot measurements at each sourcewith a time lag of approximately one month. During the dry season,when no rain occurs, the flows will represent a baseflow originatingfrom the groundwater.
The two measurements will give information on the rate of depletionof the ground, -water reservoir. Based on information from permanent Ma.stations, the depletion curve can be extended and a 10-year minimumflow estimate arrived at*
IIIIIIIIIIIIIIIIIIIII
4.2 Recession curve
When a groundwater reservoir is the only source of a stream,which will be the case at the end of the dry. season, thedischarge will decrease exponentially» Thus, the process canbe described by the equation
Q2 = Qx x e •Wt2"tl)> where
Q, is discharge at the time t.
Q. is discharge at the time t.
k is a constant varying from catchment to catchment
The constant k can thus be calculated from two measurements ofdischarge spaced in time such as to give a reasonable accuracy.
If the time of the annual minimum flow can be estimated, then thesame equation can be applied to yield the annual minimum. Thisminimum flow can then be scaled to give the 10-year minimum flowwhen compared to the hydrological regime of an adjacent Maji-station with a long record.
5. D M a COLLECTION AND ANALYSIS
5.1 Spot Measurements
The spot measurements are carried out at all selected villagescheme sources. These sources appear as a result of the screeningprocedure and are given in Appendix 2.1, 2.2 and 2-3- The timelag between the two measurements will be approximately one monthand the measurement form (Appendix 3.1) will be filled in.In addition to the measurements, questions will be. asked at thelocal level regarding the reliability of the particular stream(is it ever running dry, how often etc ).
5.2 Majl-station minimum flow
By the end of the dry season data on the lowest recorded level(time and gauge height) at the permanent hydro-stations in thearea shall be collected. These levels shall be conv-erted to dis-charges using the available rating curves and the 1984 minimumflow is arrived at for the hydrostations. This flow is thencompared with the 10-y ear minimum at the sane station and theratio Is calculated.
DISTRICT
MAKETE
ir
IT
1!
Il
fl
LUDEWA
if
iit
VILLAGE/GROUP
Klsinga,single,
Ihanga, single
Ukwama, single
Masisiwe, single
Mbalatse single
Igolwa, single
Ukange, single
Mawengi,single
Itundu Group
Madunda, single
Madilu, single
Lugarawa, single
Lullo Group
R£G.NO.
303
324
195
325
. 319
196
320
95
1 - 5 6
94
96
_ 108
1 - 5 8
HYDROZONE
3
4
4
3-4
3
4
i*
4
4
4
4
4
1
R E M A R K S
3 year plan
2 intakes
Total No. of Schemes
RUVUMA REGION APPENDIX NO. 2 . 2 HYDRO MEASUREMENTS
DISTRICT
SONGEAit
M
II
Tt
M
It
II
tt
tt
tt
tt
tt
tt
t»
tt
tf
It
Itn
•1
ii
it
MB ING Att
tt
M
it
tt
it
M
ti
it
M
VILLAGE/GROUP
Libango Group
Namabengo Group
Mpitimbi Group
MuhukurU Group
Magagura, single
Ngahokora, single
Matimira, single
Nakahuga, single
Peramino Group
Lipokela Group
Mbinganfaalule, single
Limamu, single
Lilondo, single
Hanga, single
Mlilayoyo, single
Mbimbi» single
Namangole Group
Kilangalanga, single
Ngvinde, singleMawama, singleNamatuhi, sinale
Njalamatata GroupLundo Group
Mango Group
Ngindo, single
Litembo, single
Ndumbi, single
Kindinba Chini/Juu
Linda,* single
Kihangi Mahuka
Silo, single
Wukiro, single
Mahenge, single
REG. NO.
R - 3
R - 6
R - 14
R -. 16
133
134
66
120
R - 8
R - 12
131
96
93
77
79
101
R - 10
271
'7°g141154
R - 11R - 25
R - 21
167
193
186
188
202
227
203
197
303
HDROLZONE
2
2 «•
2 - 3
2
2
2
2
3
. 3
3
3
2
4
3
3
2
2
2
2323
2
2
2
2
2
22
2
2
2
R E M A R K S
3 year plan
tt
tt
tt
tt
tt
2 intakes
3 year planif
tt
it
2 intakes
IIIIIII1IIII1II1IIIII
DISTRICT
M3INGAft
it
rt
i t
i t
it» •
ii
TUNDURUtt
«i
tt
ti
tt
tt
n
n -
VILLAGE/GROUP
Myangayanga Group
Miya« Group
Sepukila, single
Malindindo, single
Mikalanga, single
Mpepai, single
Mbamba Bay, GroupManipili Liwihi,singl<
Nanaanoo smaieMatemanga Group
Nandembo single
Machemba Group
Naluwal» Group
Atoani Group
Kindamba single
Misyaje single
Njenga single
Marumba Group
REG. NO"!'' ,
R - 19
R - 23
243
21"5
214 ,
244
R - 28: 225
162R - 31
40
R - 34
R - 35
R - 38
802
254
8
R - 40
.HYDROZONE
2
2
2
2
2
2
222
1
1
1
1
1
1
1
1
1
R E M A R K S
3 year p lan
tt
H
" 2 intakes
3 year plani?
#
Total No. of Schemes : 52
IIIIIIIIIIIIIIIIIIIII
APPENDIX 2.3 MEASUREMENTS
DISTRICT*
MBOZI
ILEJE
MBEYA
Rural
CHUNYA
RUNGWE
VILLAGE
Mbozi West, Group
Myovisi Group
Vwawa group
Katete, single
Ihanda, single
Isandula, single
Senjele, single
Hezva, single
Isoko, group
Itale, single
Sheyo single
Ilongo group
Mbuyuni group
Utengule group
Ikhoho, single
THfTfWV» _ tWTTllTO" • • • • • r 3 ™ w J.
Oyole group
Iwindi group
Isuto group
Itiiriba single
Rujewa group
rjumbi groupIsangala group
Mtanila group
Mgwala single
Mkwajuni single
rtijantoani single
Maleza single
Namlcukwe single
Nsigara group
rîasiabone, single
Mdaga group
Kanyelele group
REG.NO.
M - 34
M - 39
M - 42
503
435
481
380
373
M - 72
27
37
M - 7
M - 4
M - 6
146
M - 10
M - 13
M - 22
M - 26
106
M - 3
M - 8
M - 23
M - 30
514
9
11
855
14
M - 58
367
M - 45
M - 56
HXDROZONE
1
1
1
1
1
1
1
3
4
4
4
2
2
1
1
1
2
2
3
1
1
2
2-3
1
1
1
1
1
1
4
4
3
4
R E M A R K 3
2 Intakes
3 year plan
4 intakes
Hydrant
3 year plan
3 year plan
3 year plan
3 year plan.
3 year plan Hydrarn
Cunt'd...
IIIIIIIIIIIIIIIIIIIII
4BEYA REGION ( C o n t ' d . . . ) APPENDIX 2 . 3 HYDRO MEASUREMENTS
DISTRICT*
BENGWE
KXELA
" m T O T
Ngopyolo group
Lyenje single
Nditu single
Hgana group
Ngamanga group
Sinyanga group
REG.NO.
M - 65
•308
321
M - 70
M - 67
M - 68
HYDROZONE
4
4
4
4
4
4
R E M A R K S
TOTAL No. of Schemes: 39
IIIIIIIIIIIIIIIIIIIII
C C R K
2.
3.
LOW FLOW MEASUREMENT PROGRAMME '
1. VILLAGE
Name >•
Region
District
Single Scheme Planned •
Group Scheme Planned • Reference
SOURCE
Name
Spring Source
Stream
Measurement at
D
D
• Intake site as shown on Village Sketch
D Other site, describe location
••••»••*•**«*•*< >•*•••***•••***•*«•*••*•****••##***<
MEASUREMENT
Date of Visit 19 ...
Method Ï V-notch Q Bucket • oct-aeter
V-notchî Head measured in notch (h..) .•*.*...-....... cmLength top of weir to water level (left) (1.) cmLength top of weir to water level (right) (tj) cm
Bucket : Volume of bucket(V) litres
Time to fill bucket ( O seconds
Time to fill bucket (t«) seconds
Average time (t ) seconds
Ott-meter: Use Maji standard form to fill in and calculate discharge
IIIIIIIIIIIIIIIIIIIII
'RELIABILITY OF MEASUREMENT
V-notch : Is all water passing the V-notch or is it bypassed;
de scribe ..*•••..••••••r •
Has V-notch been placed horizontally describe any
deviation •.*••
Bucket : Is bucket well calibrated
Is all flowing water collected describe
OTT-Meter ; How many verticals in cross-section has been measured
•••••••••*•••••*>•>>••••••••>*•••>••••••••••••*••#••••
Which heights over river bed has been used for measuring
Q 0.6 Q 0.2/0.8
Describe Site:
Bed : O Rocky
• Stones, boulders
Q gravel
D sand
• silt/clay
Bank : D no vegetation
D some vegetation
• vegetation inteferes with measurement
I1
5. SOURCE RELIABILITY ( INTERVIEW )• • ' • . -
« Is there a flow at the source all year round
Has anybody experienced the source being dry
IHow often does the source dry up v G twice a yearI
IIII
DD
aa,
yes
no
yes
no
D once a year
O once in two years
D less than once in 2 years
D many people
D only few
• How many people collects water from
* the stream Q the whole village
I• If the source runs dry where is water then collected
6. DISCHARGE CALCULATION
I V-notch : Calculate H • I,- (1« + Ij)/^ » .................. cm
From Table 1 find Q " m 1/s
Bucket : Calculate Q = V/t » 1/s
• Ott-mftter : Calculate Q from standardMaji calculation form
Field Team Leader Signature Date
DEFINITION SKETCH
* ,
on.
NOTE : y MUST BE > 5 CM.
IIIIIIIIIIIIIIIIIIIII
COWIconsult(TANZANIA)
Consulting Engineers and Planners Ltd.
TABLE 1 !
Discharge in 1/s for 90° V-notch
(Head H in cm ) Q = 0.0 148 x H2'48
Headcm
1.02.0
.. 3.04.0
5.0•5
6.0.5
7.0.5
8.0.5
9.0.5
10.0•5
11.0.5
12.0.5
13.0.5
14.0.5
15.0 •.5
16.0.5
17.0.5
13.0.5
DischargeI/a
0.0150.082
0.220.46
0.80- 1.01
1.261.54
1.852.19
2.562.99
3.443.93
4.475.04
5.666.32.
7.027.77
8.569.40
10.311.2
12.213.3
14.315.5
16,717.9.
19.220.6
Head,cm
19.0 '.5
20.0.5
21.0.5
22.0.5
23.0.5
24.0•5
25.0•5
26.0.5
27.0.3 — -
28.0•5
29.0.5
30.0.5
31.0•5
32.0.5
33.0.5
34.0•5
Discharge1/s
21.923.4
24.926.5
28.129.8
•• 31.633.4
35.337.2
39.241.2
43.445.5
47.850.1
52.554.9
57.460.0
62.765.3
68.271.0
73.976.9
30.083.1
36.389.6
92.996.4
