Figure 1
An example of a retention tank (1 - inlet canal, 2 - outlet canal, 3 - flow chamber, 4 – accumulation chamber) [28].
Figure 2
An example of an additional transit canal (1 – sewer canal, 2 - sewer manhole, 3 - additional transit canal) [28].
Figure 3
An example of a rainwater system equipped with a retention sewage canals (1 - canal, 2 - piling partitions, 3 - manhole) [28].
Figure 4
Scheme of the damming partition installed in a sewage manhole (a) cross section; (b) longitudinal section; 1 - sewer manhole, 2 - overflow edge, 3 - piling partition, 4 - flow opening, 5 – canal, DO,RK – diameter of the flow opening, dk - diameter of canal, hRK,t – rainwater height in the canal during the time t, Hzał - maximum acceptable height of rainwater before the damming partition [9].
Figure 5
Scheme of the retention sewage canal with damming partitions that create stormwater canal retention spaces (the light blue - average distribution of the liquid stream mirror in the conduits of a traditional rainwater systems; the blue - liquid stream distribution and retention capacity of the rainwater sewage system after equipping it with damming partition), LKR—distance between adjacent damming partitions [7].
Figure 6
The scheme of the model catchment, total drainage area F = 80 ha (developed based on [1]).
Table 1
A set of basic hydraulic parameters of the traditional rainwater system.
| The traditional rainwater sewage system | ||||
|---|---|---|---|---|
| No. | Conception | Slope of canals bottom | Maximum value of rainwater outflow from the traditional rainwater sewer at outlet node | Calculative time for rainwater sewage system dimensioning |
| - | - | ik, ‰ | QoTmax, dm3/s | tm, min |
| 1. | Conception I | 1 | 2887.7 | 32 |
| 2. | Conception II | 2 | 3692.8 | 26 |
| 3. | Conception III | 3 | 4175.8 | 25 |
Table 2
A Set of the values of the basic hydraulic parameters of the innovative rainwater sewage with retention canals system.
| The innovative rainwater sewage system (traditional sewage system after installation of damming baffles) | |||||||
|---|---|---|---|---|---|---|---|
| No. | Conception | Considered variant | Slope of canals bottom | Maximum value of rainwater outflow from the innovative rainwater sewer at outlet node | Calculative time for innovative rainwater sewage system dimensioning | Damming baffles spacing | Rainwater flow reduction coefficient |
| - | - | - | ik, ‰ | QoImax, dm3/s | tM, min | LKR, m | βKR, - |
| 1. | Conception I | Variant 1 with LKR1 | 1 | 981.6 | 88 | 200 | 0.34 |
| 2. | Variant 2 with LKR2 | 1 | 1063.4 | 84 | 300 | 0.37 | |
| 3. | Variant 3 with LKR3 | 1 | 1159.6 | 78 | 400 | 0.40 | |
| 4. | Conception II | Variant 1 with LKR1 | 2 | 1775.1 | 56 | 200 | 0.48 |
| 5. | Variant 2 with LKR2 | 2 | 2120.8 | 46 | 300 | 0.57 | |
| 6. | Variant 3 with LKR3 | 2 | 2362.8 | 42 | 400 | 0.64 | |
| 7. | Conception III | Variant 1 with LKR1 | 3 | 2445.3 | 40 | 200 | 0.59 |
| 8. | Variant 2 with LKR2 | 3 | 2899.5 | 34 | 300 | 0.69 | |
| 9. | Variant 3 with LKR3 | 3 | 3118.8 | 30 | 400 | 0.75 | |
Figure 7
Maximum rainwater outflow at the outlet from the drainage catchment for traditional storm water system QoTmax and innovative storm water system QoImax, catchment area F = 80 ha (developed on the basis of [1]).
Table 3
A comparison of rainwater outflow from traditional and innovative sewer system taking into account different variants of their working.
| Ratio of maximum rainwater outflow traditional to innovative system, at various slope of canals bottom ik and damming baffles spacing RLK | |||
|---|---|---|---|
| ik = 1 ‰ | ik = 2 ‰ | ik = 3 ‰ | LKR, m |
| 2.9 | 2.1 | 1.7 | LKR1 = 200 m |
| 2.7 | 1.7 | 1.4 | LKR2 = 300 m |
| 2.5 | 1.6 | 1.3 | LKR3 = 400 m |
Figure 8
Hydrograms of rainwater outflow from the traditional and innovative sewer system at rainfall duration td = 25 minutes, drainage catchment area F = 80 ha, canal bottom slope ik = 2 ‰ and surface runoff coefficient Ψ = 0,5 [1].
Figure 9
Calculative time for rainwater sewage system dimensioning tm and calculative time for innovative rainwater sewage system dimensioning tM (based on [1]).
Table 4
Comparison of calculative time tm and tM for different variants of sewer system working.
| The slope of canals bottom | Calculative time for rainwater sewage system dimensioning | Calculative time for innovative rainwater sewage system dimensioning | The difference between the calculative duration of rainfall for the dimensioning of the traditional rainwater system tm and the sewage equipped with a retention canals system tM ΔT = tM − tm | Damming baffles spacing |
|---|---|---|---|---|
| ik, ‰ | tm, min | tM, min | ΔT, min | LKR, m |
| 1 | 32 | 88 | 56 | LKR1 = 200 m |
| 1 | 32 | 84 | 52 | LKR2 = 300 m |
| 1 | 32 | 78 | 46 | LKR3 = 400 m |
| 2 | 26 | 56 | 30 | LKR1 = 200 m |
| 2 | 26 | 46 | 20 | LKR2 = 300 m |
| 2 | 26 | 42 | 16 | LKR3 = 400 m |
| 3 | 25 | 40 | 15 | LKR1 = 200 m |
| 3 | 25 | 34 | 9 | LKR2 = 300 m |
| 3 | 25 | 30 | 5 | LKR3 = 400 m |
Figure 10
Values of the coefficient of γTM depending on the sewer slope ik and spacing of damming partitions LKR (based on [1]).
Figure 11
Rainwater flow reduction coefficient βKR in innovative rainwater system for different slopes of canals ik and damming baffle spacing LKR (based on [1]).
Figure 12
The relationship between the rainwater flow reduction coefficient βKR and the critical time tM (based on [1]).