Does a Lower Non-Revenue Water Level Always Mean Better Performance?

Transcription

1 Does a Lower Non-Revenue Water Level Always Mean Better Performance? Eng. Taha AL-Washali, IHE-Delft Dr. Saroj Sharma, IHE-Delft Prof. Maria Kennedy, IHE-Delft Prof. Fadhl AL-Nozaily, WEC Dr. Mansour Haidera, WEC IWA Pi Conference 15 th - 17 th May, 2017 Vienna, Austria Photo: Water and Environment Center Sana a University 1

2 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 2

3 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 3

4 Volume of water per year (MCM) Overview of Sana a water status Yemen water-scarce country in the middle east Sana a water table drops 7 meters annually Sana a Basin Demand and Supply Renewable Abstraction Deficit Source: WHO (1997) Source: JICA (2007) 4

5 Overview of Sana a water supply Water sources: 114 deep wells ( m deep) Network age: > 40 years Customers: 90,000 (1 million people) System: combined; gravity and pumped Supply pattern: intermittent (once a week: 4 hrs/day) 5

6 Sana a water supply network Sana a Water Supply Network Administrative Zones and Distribution Areas in Sana a 6

7 NRW level in Sana a water supply system 60 Non-Revenue Water in Sana a Water Supply System NRW (%) Avg. =35% Time Source of data: SWSLC,

8 NRW level in Sana a water supply system 8

9 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 9

10 Volume (m3) Non-revenue water vs. system input volume 3,E+07 Annual NRW level vs. SIV level in Sana'a system 2,E+07 SIV BW NRW 0,E

11 Volume (m3) Non-revenue water vs. system input volume Monthly NRW level vs. SIV level in Sana'a system 2,E+06 1,E+06 SIV BW NRW 0,E+00 Jan. 05 Jan.06 Jan.07 Jan.08 Jan.09 Jan.10 Jan.11 Jan.12 Jan.13 Jan.14 Jan.15 11

12 Volume (m3) Non-revenue water vs. system input volume NRW level vs. SIV level in a DMA in Sana'a SIV BW NRW 0 12

13 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 13

14 System Input Volume (MCM) NRW performance indicators System characteristics Year Number of connections - 88,936 94,723 Length of mains (km) Average pressure (m) Supplied water (m3/yr) 22,290,314 7,441,435 Supplied water decrease

15 Volume (m3) NRW performance indicators Annual NRW level performance vs. SIV level indicators Sana'a system 3,E+07 2,E+07 0,E+00 Year NRW (m 3 /yr) 8,637,692 1,604,557 NRW (%) 39% 22% NRW (L/c/d) NRW (L/c/d/m pressure) 27 5 Apparent Losses (AL) (m 3 /yr) 5,922,050 1,100,093 AL (m 3 /day) 16,225 3,014 AL (L/c/d) AL (L/c/d/m pressure) 18 3 AL (%of SIV) 27% 15% ALI Real Losses (RL) (m 3 /yr) 2,601, ,259 RL (m 3 /day) 7,127 1,324 RL (L/c/d) RL (L/c/d/m pressure) ILI SIV BW NRW 15

16 NRW PIs when-system-is-pressurized NRW performance indicators (w.s.p) Year Average supply time (hr/day) Average supply time (day/year) NRW (m 3 /day w.s.p.) 129, ,842 NRW (L/c/d w.s.p.) 1,451 1,856 NRW (% w.s.p) 39% 22% RL (L/c/d w.s.p.) AL (L/c/d w.s.p.) 995 1,273 ILI w.s.p ALI w.s.p

17 NRW PIs (w.s.p.) sensitivity of supply time 17

18 Has NRW level increased or decreased? Traditional approach w.s.p. approach NRW % % % 39% 22% -44% 39% 22% -44% Litre/connection/day % % 18

19 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 19

20 NRW (m3) NRW leveling and re-leveling Monthly NRW vs. SIV in Sana'a ( ) NRW= SIV R² = SIV (m3) 20

21 NRW (m3) NRW leveling and re-leveling Five year NRW equation for Sana'a ( ) NRW = SIV 2,000,000 R² = SIV (m3) 21

22 NRW leveling and re-leveling NRW-SIV regression equation to be generated. Volume and PIs of NRW for the baseline year can be normalized at the today s system input volume; or any SIV. A comparison of the NRW PIs for two different years at the same SIV can be made to assess the progress of NRW management. This would help in monitoring NRW status and projects when the supplied water is increasing! Or when shifting from intermittent to continuous supply. 22

23 NRW (m3) NRW leveling and re-leveling Monthly NRW equation for a DMA in Sana'a (2016) NRW = SIV R² = SIV (m3) 23

24 Content 1. Overview of Sana a water supply 2. Non-revenue water vs. system input volume 3. NRW performance indicators 4. NRW leveling and re-leveling 5. Conclusions 24

25 Conclusions NRW varies where SIV varies. A lower NRW level doesn t necessarily mean better performance; it might be due to a decrease of supplied water. A higher NRW level doesn t necessarily mean worse performance; it might be due to an increase of supplied water. Monitoring the NRW management policies is still challenging for utilities with fluctuating water production. 25

26 Conclusions The extended w.s.p. approach could be a solution. However: it favors utilities with increasing supplied water and vice versa. It is still not certain whether this approach indicates the actutal status of NRW. For utilities with average supply time less than 8 hr/day, this approach is more uncertain. All NRW PIs work under this approach except the apparent loss index. Another potential method: NRW-SIV regression equation (e.g. every year). NRW releveling can allow comparison of two years at one SIV Requires historical data; correlation coefficient should be >

27 Thank You. 27