On the basis of the analysis, findings and conclusions drawn above, the following recommendations are made aimed at reducing leakages in water distribution systems:
i. Further research should be done to match the determined leakage exponents (N1) with actual field measurements in other areas that have similar characteristics with either Chinyonga or BCA district metered area.
ii. Further studies should also be done to confirm the use of burst frequency exponent (N2) as a tool for making pipeline replacement decisions in other areas.
iii. Burst frequency exponent (N2) must also be determined for other places/locations to confirm if there is a relationship particularly in developing countries for systems that have constant water supply.
iv. Understanding the relationship between pipe material and leakage exponent is very important for the purpose of making quick estimates for leakage flow rates. In this regard, further studies should be done to develop a model where proportion of pipe materials could be input and age as well as other factors to come up with N1 exponents.
v. The utility in the Blantyre water supply area must start active leakage control in view of the fact that the economic level of leakage has been exceeded so as to manage their real losses efficiently.
vi. Pressure reduction should be implemented in areas where high pressures can be reduced significantly irrespective of payback periods based on leakage/pressure and pressure/burst frequency relationships.
vii. Replacement of water mains should commence as a matter of urgency in the Blantyre water supply area as continued pipe repairs only would not be cost effective bearing in mind the cost of lost water. The decision is based on the findings by ECONOLEAK model for the entire supply area analysis.
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APPENDICES
APPENDIX A1 SPECIFICATIONS OF EQUIPMENT USED
SPECIFICATIONS FOR THE DATA LOGGERS (COSMOS AND SEWAD 30)
SPECIFICATION FOR THE FLEXIM ULTRASONIC FLOWMETER Flexim Fluxus ADM 6725
Flexim Ultrasonic Flowmeter Model : Fluxus ADM 6725 Ser. No : 02503151
Built : 2007
Temp. -20 to 600C
Made in Germany
Input parameters during the investigation:
Outer diameter 125.0 mm Wall Thickness 12.5 mm
Pipe Material Asbestos Cement
Lining No
Roughness 0.1 mm
Medium Water
Medium Temperature 18.00C
Transducer type Standard
Measuring Point No 5555
Sound Path 2
Transducer Distance 36.5 mm
Starts recording flows in m3/h Sewad 30 Data Logger
Pressure Range min/max 0.2 31.0 [bars]
Temperature Range min/max 0 50 [0C]
Sewad30 Type W Swiss made Cosmos Data Logger
H. Meinecke AG
CDL-4U No. 100538 (10/97) Casing: Cast aluminium
Weight: app 1200 g
Dimensions: 220 x 105 x 70 mm
Operating temp.: 0 … 50oC Storage temp.: -10 … +70oC Evaluation software CDLWin
APPENDIX A2 STRUCTURE AND FORMULATION OF SANFLOW MODEL (ANALYSIS SOFTWARE)
The SANFLOW model structure and formulation according to McKenzie (1999) followed the following steps and equations:
Estimation of Normal Night Use for Night Flow
Domestic night use = Population x percentage of population active per hour x size of toilet cistern………..………...………(1) For small and large non-domestic use the result would be zero.
Total normal night use = domestic night use + small and large non-domestic night use………..(2) Estimation of Background Leakage for Night
Mains losses = length of pipelines (km) x background loss from mains (litres /km/h)
……..………...(3) Connection losses = number of connections x background losses for conn. ( litres /con/h)
……….…...(4) Property losses = number of properties x background losses for properties (litres /con/h)
……….……...(5) Total background losses = Mains losses + Connection losses + property losses……….…....(6) Pressure correction factor (pcf) for background losses =
5 . 1
50 ⎟
⎠
⎜ ⎞
⎝
⎛operatingpressure
…………...……….(7) Total background leakage at operating pressure = total background losses at 50m x pcf…...(8) Estimation of Unaccounted-for Leakage in Night Flow
Total expected night use = total normal night use + total background leakage at the operating pressure
………..………...…(9) Unexplained leakage = Measured minimum night flow - Total expected night use.……...(10) Estimation of Equivalent Service Pipe Bursts in Night Flow
Standard equivalent service pipe burst (@ 50 m) is assumed as 1.60 m3/h.
Pressure correction factor (pcf) for bursts =
5 . 0
50 ⎟
⎠
⎜ ⎞
⎝
⎛operatingpressure
………....…(11) Leakage from one equivalent service pipe burst = 1.60 x pcf for bursts ………..………....(12) Expected number of equivalent service pipe bursts = Unaccounted-for leakage/leakage from one equivalent service pipe burst ………...(13)
APPENDIX B1 NON-REVENUE WATER TREND FOR THE BLANTYRE WATER SUPPLY SYSTEM
Month Produced (m3)
Sold (m3) Disparity (m3)
NR W
%
Total Conne ctions
NRW (in m3/conn/
yr)
Total length of Pip. (km)
NRW (in m3/km/yr)
July 2001 2,229,064 1,417,546 811,518 36% 28807 338.05 1069 9109.65 August 2001 2,213,669 1,318,010 895,659 40% 373.10 10054.17 September 2001 2,268,541 1,497,872 770,669 34% 321.03 8651.10 October 2001 2,310,686 1,451,037 859,649 37% 358.10 9649.94 November 2001 2,333,699 1,474,080 859,619 37% 358.09 9649.61 December 2001 2,178,897 1,344,880 834,017 38% 347.42 9362.21 Yearly Figures 13,534,556 8,503,425 5,031,131 37% 30070 334.63 1075 9360.24 January 2002 2,359,032 1,376,370 982,662 42% 30070 392.15 1075 10969.25 February 2002 2,031,846 1,328,075 703,771 35% 280.85 7856.05 March 2002 2,232,621 1,290,961 941,660 42% 375.79 10511.55 April 2002 2,195,751 1,344,608 851,143 39% 339.66 9501.13 May 2002 2,292,155 1,294,968 997,187 44% 397.95 11131.39 June 2002 2,161,058 1,367,523 793,535 37% 316.68 8858.07 July 2002 2,333,426 1,317,273 1,016,153 44% 405.51 11343.10 August 2002 2,218,386 1,460,662 757,724 34% 302.38 8458.31 September 2002 2,223,813 1,361,696 862,117 39% 344.04 9623.63 October 2002 2,364,711 1,436,799 927,912 39% 370.30 10358.09 November 2002 2,292,626 1,569,824 722,802 32% 288.45 8068.49 December 2002 2,283,310 1,441,926 841,384 37% 335.77 9392.19 Yearly Figures 26,988,735 16,590,685 10,398,050 39% 31015 335.26 1088 9557.03 January 2003 2,294,512 1,437,384 857,128 37% 31015 331.63 1088 9453.62 February 2003 2,129,239 1,318,501 810,738 38% 313.68 8941.96 March 2003 2,084,586 1,313,290 771,296 37% 298.42 8506.94 April 2003 2,292,407 1,230,622 1,061,785 46% 410.81 11710.86 May 2003 2,454,831 1,214,229 1,240,602 51% 480.00 13683.11 June 2003 2,241,775 1,554,493 687,282 31% 265.92 7580.32 July 2003 2,444,210 1,150,790 1,293,420 53% 500.44 14265.66 August 2003 2,402,700 1,780,073 622,627 26% 240.90 6867.21 September 2003 2,359,272 1,392,479 966,793 41% 374.06 10663.16 October 2003 2,499,491 1,068,759 1,430,732 57% 553.56 15780.13 November 2003 2,418,979 1,869,935 549,044 23% 212.43 6055.63 December 2003 2,406,172 919,589 1,486,583 62% 575.17 16396.14 Yearly Figures 28,028,174 16,250,144 11,778,030 42% 32444 363.03 1103 10678.18 January 2004 2,260,909 1,266,180 994,729 44% 32444 367.92 1103 10822.07 February 2004 2,296,777 1,252,746 1,044,031 45% 386.15 11358.45 March 2004 2,446,623 1,211,497 1,235,126 50% 456.83 13437.45 April 2004 2,396,213 1,289,840 1,106,373 46% 409.21 12036.70 May 2004 2,401,269 1,161,307 1,239,962 52% 458.62 13490.07 June 2004 2,438,881 1,381,409 1,057,472 43% 391.13 11504.68 July 2004 2,581,387 1,197,617 1,383,770 54% 511.81 15054.61 August 2004 2,557,979 1,315,877 1,242,102 49% 459.41 13513.35 September 2004 2,748,688 1,159,935 1,588,753 58% 587.63 17284.71 October 2004 2,562,198 1,367,480 1,194,718 47% 441.89 12997.84 November 2004 2,438,044 1,264,713 1,173,331 48% 433.98 12765.16 December 2004 2,553,484 1,365,911 1,187,573 47% 439.25 12920.11 Yearly Figures 29,682,452 15,234,512 14,447,940 49% 33365 433.03 1128 12808.46 January 2005 2,480,580 1,275,226 1,205,354 49% 33365 433.52 1128 12822.91 February 2005 2,538,117 1,138,953 1,399,164 55% 503.22 14884.72 March 2005 2,701,068 943,790 1,757,278 65% 632.02 18694.45
Appendix B1 continued…
Month Produced
(m3)
Sold (m3) Disparity (m3)
NR W
%
Total Conne ctions
NRW (in m3/conn/
yr)
Total length of Pip. (km)
NRW (in m3/km/yr)
April 2005 2,552,607 1,586,435 966,172 38% 347.49 10278.43 May 2005 2,557,196 1,258,901 1,298,295 51% 466.94 13811.65 June 2005 2,504,427 1,231,474 1,272,953 51% 457.83 13542.05 July 2005 2,487,602 1,195,422 1,292,180 52% 464.74 13746.60 August 2005 2,403,129 1,272,497 1,130,632 47% 406.64 12028.00 September 2005 2,364,876 1,135,766 1,229,110 52% 442.06 13075.64 October 2005 2,424,574 1,304,722 1,119,852 46% 402.76 11913.32 November 2005 2,202,921 1,261,850 941,071 43% 338.46 10011.39 December 2005 2,246,019 1,083,691 1,162,328 52% 418.04 12365.19 Yearly Figures 29,463,116 14,688,727 14,774,389 50% 34136 432.81 1133 13040.06 January 2006 2,313,833 1,216,474 1,097,359 47% 34136 385.76 1133 11622.51 February 2006 2,260,055 1,164,954 1,095,101 48% 384.97 11598.60 March 2006 2,524,610 946,664 1,577,946 63% 554.70 16712.58 April 2006 2,543,838 1,003,636 1,540,202 61% 541.43 16312.82 May 2006 2,640,812 1,282,122 1,358,690 51% 477.63 14390.36 June 2006 2,573,611 1,092,463 1,481,148 58% 520.68 15687.36 July 2006 2,585,130 1,290,047 1,295,083 50% 455.27 13716.68 August 2006 2,564,777 1,114,455 1,450,322 57% 509.84 15360.87 September 2006 2,197,788 1,550,331 647,457 29% 227.60 6857.44 October 2006 2,641,520 1,041,631 1,599,889 61% 562.42 16944.98 November 2006 2,612,549 1,279,505 1,333,044 51% 468.61 14118.74 December 2006 2,532,540 924,833 1,607,707 63% 565.17 17027.79 Yearly Figures 29,991,063 13,907,115 16,083,948 54% 34458 466.77 1140 14108.73 January 2007 2,576,860 1,007,918 1,568,942 61% 34458 546.38 1140 16515.18 February 2007 2,262,142 1,224,886 1,037,256 46% 361.22 10918.48 March 2007 2,395,794 1,106,366 1,289,428 54% 449.04 13572.93 April 2007 2,327,041 850,569 1,476,472 63% 514.18 15541.81 May 2007 2,348,357 1,219,036 1,129,321 48% 393.29 11887.59 June 2007 2,232,877 1,155,953 1,076,924 48% 375.04 11336.04 July 2007 2,387,789 920,199 1,467,590 61% 511.09 15448.32 August 2007 2,372,290 1,108,703 1,263,587 53% 440.04 13300.92 September 2007 2,264,515 1,261,378 1,003,137 44% 349.34 10559.34 October 2007 2,545,564 1,334,014 1,211,550 48% 421.92 12753.16 November 2007 1,992,247 1,255,652 736,595 37% 256.52 7753.63 December 2007 2,324,014 1,015,617 1,308,397 56% 455.65 13772.60 Yearly Figures 28,029,490 13,460,291 14,569,199 52% 34959 416.75 1155 12614.03 January 2008 2,366,948 1,228,302 1,138,646 48% 34959 390.85 1155 11830.09