conditions” could reasonably be assumed to represent the leakage value at other
normal flow conditions in the sanitary drainage system.
2. Routine inspection of sanitary sewers is essential. Leakage from sanitary sewers
has serious health impacts because there is a possibility of cross-connection with
the potable water system [29]. The best method of inspection is to pass a small
television camera through the sewer, which is also necessary to make sure that the
sewer is well maintained to avoid blockage and leakage.
5.3 Leakage from the Storm Drainage System
1. The leakage rates in two districts, both of which being served by storm drainage
sewers, were 5.4% and 4.1% with a weighted average of 4.5%.
2. The rainfall intensity (i) in Ar-Riyadh for a 50-year return period and duration of
1 hour is about 28 mm/hour. Thus, the quantity of storm water drained from an
urbanized catchment area (A) of 25 ha, based on the rational formula
(Q ¼ 2.76 CiA) [30], would be ¼ (2.76) (0.36) (28 mm/hour) (25 ha) ¼ 690 L/
s ¼ 2500 m
3 for a duration of 1 hour. Consequently, in 2015, the amount of
leakage from the storm sewers could reach 4.5% of 2500 ¼ 113 m
3 /storm in a
typical 25 ha area and up to 700,000 m
3 /day in the sewered parts of the city.
3. Storm drainage sewers in Ar-Riyadh are now frequently being used for
discharging groundwater collected by subsurface drains and by dewatering projects. Consequently, it is expected that considerable leakage from these storm
sewers could occur in the lower reaches where the water depth in the sewer
is high.
4. For storm drainage sewers, which carry major flows, it is essential that routine
inspection be carried out. As for sanitary sewers, inspection can be made by
passing a small television camera through the sewer to locate leaks, incrustations,
and failures. Repairs should be made promptly.
6 Conclusions and Recommendations
1. Leakage from municipal utilities varies greatly from area to area even in the same
city. Leakage from the potable water network in five locations of Ar-Riyadh
varied between 10% and 24%.
2. Leakage increased exponentially with rising pressure to an even greater extent
than would be predicted by the orifice equation.
3. The impacts of water losses from networks are very significant from multiple
aspects:
• Direct economic loss (estimated at around a minimum of USD 300 million per
year in Ar-Riyadh)
• Loss of an important resource especially important where water is scarce, as in
Saudi Arabia [31, 32]
252
N. K. Shammas et al.
normal flow conditions in the sanitary drainage system.
2. Routine inspection of sanitary sewers is essential. Leakage from sanitary sewers
has serious health impacts because there is a possibility of cross-connection with
the potable water system [29]. The best method of inspection is to pass a small
television camera through the sewer, which is also necessary to make sure that the
sewer is well maintained to avoid blockage and leakage.
5.3 Leakage from the Storm Drainage System
1. The leakage rates in two districts, both of which being served by storm drainage
sewers, were 5.4% and 4.1% with a weighted average of 4.5%.
2. The rainfall intensity (i) in Ar-Riyadh for a 50-year return period and duration of
1 hour is about 28 mm/hour. Thus, the quantity of storm water drained from an
urbanized catchment area (A) of 25 ha, based on the rational formula
(Q ¼ 2.76 CiA) [30], would be ¼ (2.76) (0.36) (28 mm/hour) (25 ha) ¼ 690 L/
s ¼ 2500 m
3 for a duration of 1 hour. Consequently, in 2015, the amount of
leakage from the storm sewers could reach 4.5% of 2500 ¼ 113 m
3 /storm in a
typical 25 ha area and up to 700,000 m
3 /day in the sewered parts of the city.
3. Storm drainage sewers in Ar-Riyadh are now frequently being used for
discharging groundwater collected by subsurface drains and by dewatering projects. Consequently, it is expected that considerable leakage from these storm
sewers could occur in the lower reaches where the water depth in the sewer
is high.
4. For storm drainage sewers, which carry major flows, it is essential that routine
inspection be carried out. As for sanitary sewers, inspection can be made by
passing a small television camera through the sewer to locate leaks, incrustations,
and failures. Repairs should be made promptly.
6 Conclusions and Recommendations
1. Leakage from municipal utilities varies greatly from area to area even in the same
city. Leakage from the potable water network in five locations of Ar-Riyadh
varied between 10% and 24%.
2. Leakage increased exponentially with rising pressure to an even greater extent
than would be predicted by the orifice equation.
3. The impacts of water losses from networks are very significant from multiple
aspects:
• Direct economic loss (estimated at around a minimum of USD 300 million per
year in Ar-Riyadh)
• Loss of an important resource especially important where water is scarce, as in
Saudi Arabia [31, 32]
252
N. K. Shammas et al.