Storm sewer systems face many challenges in urban areas, in particular those systems which are old and surpassing their design period. This study has used data from an urbanized, subcatchment covering 360 ha of dead run watershed in the Alkadeer district, Karbala, Iraq. Physically based models, Autodesk Storm and Sanitary Analysis (ASSA) and multiple nonlinear regression (MNLR), were applied. Hydrology data from 1980 to 2013 were inputted and examined over three scenarios. The results indicated that significant increase in peak flooding was produced by an increase in discharge values which may occur through a higher rainfall intensity. The model was examined and new equations were developed that may help us to better understand the hydraulic and hydrologic simulations that are identified as having the potential to better protect the environment against sudden rainfall intensities. The ratio of area of subcatchment to cross-sectional area of a pipe (
Flooding in urban storm sewer systems could cause loss of life and considerable damage [
City flooding during heavy precipitation is considered a natural phenomenon [
Efficient drainage of the rain network has a strong connection with the length of drain and time of concentration of subcatchment affecting velocity and peak runoff discharges. Urbanization also impacts hydrology, which is typically characterized by raising the values of peak flooding and reducing the time lag thus causing an increase in runoff volume [
Inundation and overland flow volume may increase up to ten times because of urbanization; flooding, which normally would have occurred once every 100 years, may be doubled by more than 30% increase in urbanization [
In recent decades, there has been much research into urban flooding with a focus on obtaining equations linking certain parameters involving topography, slope of pipes, varying rainfall intensity, size of watershed and runoff discharges, and major flooding parameters for developed areas. Attention has also been paid to the effects of climate change, varying hydraulic data on storm sewer systems, and the increasing availability of knowledge about changes in hydrological systems and insights. Many urban drainage systems can reach full capacity during heavy rainfall [
The issue of storm sewer modelling is currently one of the most dynamic areas in hydraulics and hydrology research. Many software packages have been used to simulate pipe above ground hydraulics and hydrology models in the runoff of rainfall and pollutants from urban areas, such as SWMM [
Even though there are a number of studies conducted on flooding in storm sewer systems during heavy rainfall, these studies are still very limited in their infancy. Some 2D models with high-resolution grids have examined the consequences of storm pipes [
The analysis of storm sewer systems in urban areas is considered as the most important measure taken to protect the environment in the event of intense rainfall. The analysis of a storm sewer system, postdesign and deployment, is considered the best way to ensure reliable up to a certain frequency or level of service and the ability to predict potential of serious flooding. Although many physically based and statistical models have been used for these purposes, the concept of having a model to simulate flows in urban sewers and to predict risk of flooding in urban areas is still comparatively inaccessible in many countries. The present work aims to investigate a model that can provide a better understanding of the ability of hydraulics and hydrology to predict and reduce risk of flooding in urban areas.
Karbala is an ancient festival city, situated 100 km southwest of Baghdad, Iraq (lat.-N; 32°03′51″, long.-E; 44°01′29″), in a semiarid area [
(a) Elevation map of Karbala city. (b) Map of study area Alkadeer district in Karbala city centre, Iraq, generated by GIS based on available data adapted from [
The storm sewer system was built in 2006 [
Data about the subcatchment area input to the model.
Element ID | Area (ha) | Drainage node ID | Average slope (%) | Equivalent width (m) |
---|---|---|---|---|
Sub-02 | 5.29 | 82 | 0.0100 | 110.00 |
Sub-03 | 5.45 | 81 | 0.0063 | 165.00 |
Sub-04 | 9.69 | 80 | 0.0096 | 194.00 |
Sub-05 | 9.26 | 45 | 0.0027 | 110.00 |
Sub-06 | 9.74 | 47 | 0.0043 | 140.00 |
Sub-07 | 5.80 | 83 | 0.0108 | 120.00 |
Sub-08 | 5.44 | 67 | 0.0001 | 120.00 |
Sub-09 | 6.37 | 82 | 0.0126 | 131.00 |
Sub-10 | 6.31 | 68 | 0.0000 | 149.00 |
Sub-13 | 10.10 | Out-01 | 0.0122 | 296.00 |
Sub-17 | 2.83 | 50 | 0.0130 | 117.00 |
Sub-18 | 5.20 | 41 | 0.0500 | 140.00 |
Sub-19 | 6.36 | 40 | 0.0008 | 155.00 |
Sub-20 | 5.57 | 43 | 0.0008 | 150.00 |
Sub-21 | 6.52 | 38 | 0.0234 | 191.00 |
Sub-22 | 6.50 | 27 | 0.0230 | 263.00 |
Sub-23 | 6.51 | 35 | 0.0210 | 145.00 |
Sub-24 | 5.29 | 34 | 0.0123 | 161.00 |
Sub-25 | 7.22 | 32 | 0.0113 | 196.00 |
Sub-26 | 8.07 | 22 | 0.0140 | 272.00 |
Sub-27 | 7.59 | 21 | 0.0130 | 262.00 |
Sub-28 | 7.43 | 20 | 0.0120 | 293.00 |
Sub-29 | 6.05 | 19 | 0.0110 | 275.00 |
Sub-30 | 8.22 | 53 | 0.0140 | 250.00 |
Sub-31 | 8.30 | 56 | 0.0100 | 190.00 |
Sub-33 | 4.89 | 16 | 0.0006 | 150.00 |
Sub-34 | 6.20 | 17 | 0.0120 | 280.00 |
Sub-35 | 10.59 | 13 | 0.0130 | 300.00 |
Sub-36 | 21.74 | 4 | 0.0040 | 350.00 |
Sub-37 | 7.64 | 60 | 0.0019 | 170.00 |
Sub-38 | 5.12 | 79 | 0.0085 | 170.00 |
Sub-39 | 8.72 | 3 | 0.0016 | 300.00 |
Sub-40 | 5.70 | 54 | 0.0050 | 155.00 |
Sub-41 | 6.29 | 51 | 0.0036 | 190.00 |
Sub-42 | 6.15 | 52 | 0.0100 | 180.00 |
Sub-43 | 4.59 | 69 | 0.0280 | 200.00 |
Sub-44 | 3.78 | 70 | 0.0080 | 80.00 |
Sub-45 | 4.34 | 72 | 0.0090 | 200.00 |
Sub-46 | 3.21 | 73 | 0.0086 | 60.00 |
Sub-47 | 4.62 | 75 | 0.0130 | 280.00 |
Sub-48 | 3.45 | 59 | 0.0043 | 95.00 |
Sub-49 | 3.58 | 76 | 0.0130 | 110.00 |
Sub-50 | 5.44 | 10 | 0.0006 | 175.00 |
Sub-51 | 4.73 | 1 | 0.0200 | 130.00 |
Sub-52 | 8.78 | 77 | 0.0000 | 140.00 |
Sub-53 | 7.34 | 74 | 0.0001 | 115.00 |
Sub-54 | 6.26 | 71 | 0.0006 | 95.00 |
Sub-55 | 5.33 | 49 | 0.0166 | 160.00 |
Sub-56 | 4.93 | 48 | 0.0200 | 150.00 |
Sub-57 | 5.42 | 46 | 0.0130 | 125.00 |
Sub-58 | 5.02 | 45 | 0.0170 | 130.00 |
Data about the storm sewer manhole input into the model.
Element ID |
|
|
Invert elevation (m) | Ground/rim (maximum) elevation (m) | Ground/rim (maximum) offset (m) | Initial water elevation (m) | Initial water depth (m) | Surcharge elevation (m) | Ponded area (m2) | Minimum pipe cover (m) |
---|---|---|---|---|---|---|---|---|---|---|
1 | 405460.4 | 3609285.6 | 31.97 | 34.20 | 2.23 | 32.45 | 0.48 | 34.20 | 0.00 | 1.63 |
3 | 404825.9 | 3608476.6 | 38.06 | 39.48 | 1.42 | 38.42 | 0.36 | 39.48 | 0.00 | 0.85 |
4 | 404659.7 | 3608375.1 | 38.44 | 39.86 | 1.42 | 38.80 | 0.36 | 39.86 | 2.00 | 1.02 |
7 | 404655.9 | 3608744.5 | 36.58 | 38.95 | 2.37 | 36.94 | 0.36 | 38.95 | 2.00 | 1.97 |
8 | 404811.7 | 3608848.9 | 36.09 | 38.08 | 1.99 | 36.45 | 0.36 | 38.08 | 2.00 | 1.59 |
9 | 404938.3 | 3608941.9 | 35.70 | 37.70 | 2.00 | 36.06 | 0.36 | 37.70 | 2.00 | 1.60 |
10 | 405068.8 | 3609037.5 | 35.29 | 37.62 | 2.33 | 35.65 | 0.36 | 37.62 | 2.00 | 1.93 |
11 | 405234.6 | 3609151.3 | 34.64 | 37.02 | 2.38 | 35.12 | 0.48 | 37.02 | 2.00 | 1.78 |
12 | 404658.1 | 3608176.7 | 39.27 | 40.85 | 1.58 | 39.63 | 0.36 | 40.85 | 2.00 | 1.18 |
13 | 404596.4 | 3607913.4 | 40.13 | 41.98 | 1.85 | 40.49 | 0.36 | 41.98 | 2.00 | 1.45 |
14 | 404759.6 | 3608010.3 | 38.53 | 40.29 | 1.76 | 38.89 | 0.36 | 40.29 | 2.00 | 1.36 |
15 | 404878.3 | 3608079.2 | 37.91 | 39.75 | 1.84 | 38.27 | 0.36 | 39.75 | 2.00 | 1.44 |
16 | 405008.8 | 3608156.5 | 37.24 | 38.79 | 1.55 | 37.60 | 0.36 | 38.79 | 2.00 | 1.15 |
17 | 404784.4 | 3608253.1 | 38.41 | 40.25 | 1.84 | 38.77 | 0.36 | 40.25 | 2.00 | 1.44 |
18 | 404958.3 | 3608350.2 | 37.05 | 38.75 | 1.70 | 37.41 | 0.36 | 38.75 | 2.00 | 1.30 |
19 | 405101.1 | 3608004.8 | 37.14 | 38.72 | 1.58 | 37.50 | 0.36 | 38.72 | 2.00 | 1.18 |
20 | 404968.5 | 3607934.3 | 37.63 | 39.48 | 1.85 | 38.00 | 0.37 | 39.48 | 2.00 | 1.45 |
21 | 404832.3 | 3607858.4 | 38.47 | 40.80 | 2.33 | 38.83 | 0.36 | 40.80 | 2.00 | 1.93 |
22 | 404664.4 | 3607767.0 | 40.72 | 42.60 | 1.88 | 41.08 | 0.36 | 42.72 | 2.00 | 1.48 |
23 | 405493.9 | 3608001.8 | 34.80 | 37.23 | 2.43 | 35.16 | 0.36 | 37.23 | 2.00 | 1.59 |
24 | 405377.9 | 3607953.9 | 36.24 | 38.45 | 2.21 | 36.60 | 0.36 | 38.45 | 2.00 | 1.81 |
25 | 405254.4 | 3607738.4 | 37.28 | 39.08 | 1.80 | 37.64 | 0.36 | 39.08 | 2.00 | 1.40 |
27 | 405002.5 | 3607575.6 | 39.98 | 41.56 | 1.58 | 40.32 | 0.34 | 41.56 | 2.00 | 1.18 |
28 | 405186.1 | 3607838.8 | 36.66 | 38.81 | 2.15 | 36.99 | 0.33 | 38.81 | 2.00 | 1.75 |
29 | 404913.0 | 3607674.1 | 39.37 | 41.00 | 1.63 | 39.73 | 0.36 | 41.00 | 2.00 | 1.23 |
32 | 405597.4 | 3607779.3 | 34.83 | 36.69 | 1.86 | 35.29 | 0.46 | 36.69 | 2.00 | 1.46 |
33 | 405478.4 | 3607709.2 | 35.18 | 37.49 | 2.31 | 35.54 | 0.36 | 37.49 | 2.00 | 1.91 |
34 | 405375.2 | 3607645.4 | 35.48 | 37.62 | 2.14 | 35.84 | 0.36 | 37.62 | 2.00 | 1.74 |
35 | 405259.2 | 3607575.7 | 36.77 | 38.68 | 1.91 | 37.13 | 0.36 | 38.68 | 2.00 | 1.51 |
36 | 405130.1 | 3607494.6 | 38.12 | 40.34 | 2.22 | 38.48 | 0.36 | 40.34 | 2.00 | 1.82 |
37 | 405017.0 | 3607421.9 | 39.20 | 40.73 | 1.53 | 39.56 | 0.36 | 40.73 | 2.00 | 1.13 |
38 | 404886.5 | 3607339.0 | 39.84 | 41.46 | 1.62 | 40.20 | 0.36 | 41.46 | 2.00 | 1.22 |
39 | 404732.4 | 3607244.6 | 40.29 | 42.04 | 1.75 | 40.75 | 0.46 | 42.04 | 2.00 | 1.35 |
40 | 405885.4 | 3607961.3 | 33.98 | 35.87 | 1.89 | 34.34 | 0.36 | 35.87 | 2.00 | 1.49 |
41 | 406000.7 | 3608032.0 | 32.91 | 34.90 | 1.99 | 33.27 | 0.36 | 34.90 | 2.00 | 1.59 |
42 | 406148.3 | 3608123.2 | 32.06 | 33.97 | 1.91 | 32.42 | 0.36 | 33.97 | 2.00 | 1.31 |
43 | 405708.3 | 3607847.4 | 34.50 | 36.41 | 1.91 | 34.96 | 0.46 | 36.41 | 2.00 | 1.51 |
45 | 406640.0 | 3608803.5 | 26.56 | 28.98 | 2.42 | 27.30 | 0.74 | 28.98 | 2.00 | 1.62 |
46 | 406532.6 | 3608745.8 | 26.64 | 29.29 | 2.65 | 27.28 | 0.64 | 29.29 | 2.00 | 1.85 |
47 | 406399.4 | 3608658.9 | 27.60 | 30.31 | 2.71 | 27.70 | 0.10 | 30.31 | 2.00 | 1.91 |
48 | 406251.9 | 3608568.7 | 28.56 | 31.10 | 2.54 | 28.89 | 0.33 | 31.10 | 2.00 | 1.74 |
49 | 406124.8 | 3608492.8 | 29.53 | 32.13 | 2.60 | 30.27 | 0.74 | 32.13 | 2.00 | 1.80 |
50 | 405978.3 | 3608403.8 | 29.67 | 33.23 | 3.56 | 30.31 | 0.64 | 33.23 | 2.00 | 2.76 |
51 | 405719.8 | 3608325.1 | 32.05 | 33.31 | 1.26 | 32.53 | 0.48 | 33.31 | 2.00 | 0.56 |
52 | 405586.3 | 3608238.8 | 32.38 | 34.97 | 2.59 | 32.86 | 0.48 | 34.97 | 2.00 | 1.86 |
53 | 405421.3 | 3608133.7 | 34.21 | 36.21 | 2.00 | 34.57 | 0.36 | 36.21 | 2.00 | 1.40 |
54 | 405945.9 | 3608458.4 | 30.15 | 33.18 | 3.03 | 30.63 | 0.48 | 33.18 | 2.00 | 2.38 |
55 | 405370.6 | 3608218.8 | 34.06 | 36.36 | 2.30 | 34.54 | 0.48 | 36.36 | 2.00 | 1.52 |
56 | 405307.1 | 3608325.3 | 34.25 | 36.61 | 2.36 | 34.73 | 0.48 | 36.61 | 2.00 | 1.73 |
57 | 405248.2 | 3608424.0 | 34.27 | 36.62 | 2.35 | 34.75 | 0.48 | 36.62 | 2.00 | 1.70 |
58 | 405190.8 | 3608520.2 | 34.25 | 37.10 | 2.85 | 34.73 | 0.48 | 37.10 | 2.00 | 2.12 |
59 | 405137.7 | 3608609.2 | 34.40 | 36.68 | 2.28 | 34.76 | 0.36 | 36.68 | 2.00 | 1.64 |
60 | 405071.3 | 3608721.0 | 34.48 | 37.43 | 2.95 | 34.84 | 0.36 | 37.43 | 2.00 | 2.55 |
63 | 405243.4 | 3608075.4 | 35.66 | 38.24 | 2.58 | 36.99 | 1.33 | 38.24 | 2.00 | 2.18 |
65 | 405141.4 | 3608243.0 | 36.35 | 38.15 | 1.80 | 36.71 | 0.36 | 38.15 | 2.00 | 1.40 |
66 | 405620.6 | 3608510.6 | 32.12 | 34.62 | 2.50 | 32.48 | 0.36 | 34.62 | 2.00 | 2.10 |
67 | 405836.2 | 3608640.9 | 30.94 | 33.24 | 2.30 | 31.30 | 0.36 | 33.24 | 2.00 | 1.66 |
68 | 405767.8 | 3608758.8 | 31.18 | 33.41 | 2.23 | 31.54 | 0.36 | 33.41 | 2.00 | 1.58 |
69 | 405664.6 | 3608695.7 | 32.36 | 34.61 | 2.25 | 32.72 | 0.36 | 34.61 | 2.00 | 1.85 |
70 | 405557.1 | 3608622.9 | 33.33 | 35.33 | 2.00 | 33.99 | 0.66 | 35.33 | 2.00 | 1.60 |
71 | 405708.9 | 3608861.1 | 31.13 | 33.53 | 2.40 | 31.49 | 0.36 | 33.53 | 2.00 | 1.00 |
72 | 405617.9 | 3608812.1 | 32.37 | 34.99 | 2.62 | 32.70 | 0.33 | 34.99 | 2.00 | 2.22 |
73 | 405511.0 | 3608744.5 | 34.14 | 35.89 | 1.75 | 34.40 | 0.26 | 35.89 | 2.00 | 1.35 |
74 | 405649.5 | 3608966.5 | 31.50 | 33.97 | 2.47 | 31.86 | 0.36 | 33.97 | 2.00 | 1.87 |
75 | 405548.6 | 3608911.3 | 32.97 | 35.52 | 2.55 | 33.33 | 0.36 | 35.52 | 2.00 | 2.15 |
76 | 405590.9 | 3609065.4 | 31.56 | 34.33 | 2.77 | 32.04 | 0.48 | 34.33 | 2.00 | 2.17 |
77 | 405530. | 3609166.8 | 31.72 | 34.31 | 2.59 | 32.20 | 0.48 | 34.31 | 2.00 | 1.99 |
79 | 405042.9 | 3608404.9 | 36.77 | 38.27 | 1.50 | 37.13 | 0.36 | 38.27 | 2.00 | 1.10 |
80 | 406334.6 | 3609357.0 | 20.61 | 24.95 | 4.34 | 21.10 | 0.49 | 24.95 | 2.00 | 0.00 |
81 | 406409.5 | 3609233.1 | 21.00 | 24.61 | 3.61 | 21.40 | 0.40 | 24.61 | 2.00 | 3.11 |
82 | 406485.9 | 3609106.9 | 22.18 | 27.00 | 4.82 | 22.58 | 0.40 | 27.00 | 2.00 | 4.32 |
83 | 406570.3 | 3608967.5 | 24.30 | 27.50 | 3.20 | 24.70 | 0.40 | 27.50 | 2.00 | 2.70 |
Data about the storm sewer pipes input into the model.
Element ID | From (inlet) node | To (outlet) node | Length (m) | Inlet invert elevation (m) | Outlet invert elevation (m) | Average slope (%) | Pipe shape | Pipe diameter (m) | Manning’s roughness |
---|---|---|---|---|---|---|---|---|---|
Link-01 | 39 | 38 | 180.76 | 40.29 | 39.84 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-03 | 38 | 37 | 154.62 | 39.84 | 39.20 | 0.4100 | Circular | 0.400 | 0.0130 |
Link-04 | 37 | 36 | 134.38 | 39.20 | 38.12 | 0.8000 | Circular | 0.400 | 0.0130 |
Link-05 | 36 | 35 | 152.49 | 38.12 | 36.78 | 0.8800 | Circular | 0.400 | 0.0130 |
Link-06 | 35 | 34 | 135.36 | 36.77 | 35.48 | 0.9500 | Circular | 0.400 | 0.0130 |
Link-07 | 34 | 33 | 121.29 | 35.48 | 35.18 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-08 | 33 | 32 | 138.16 | 35.18 | 34.83 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-10 | 32 | 43 | 130.16 | 34.83 | 34.50 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-11 | 43 | 40 | 210.49 | 34.50 | 33.98 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-12 | 40 | 41 | 135.30 | 33.98 | 32.91 | 0.7900 | Circular | 0.400 | 0.0130 |
Link-13 | 41 | 42 | 173.50 | 32.91 | 32.06 | 0.4900 | Circular | 0.400 | 0.0130 |
Link-14 | 42 | 50 | 328.10 | 32.06 | 29.67 | 0.7300 | Circular | 0.600 | 0.0130 |
Link-15 | 50 | 49 | 171.48 | 29.67 | 29.53 | 0.0800 | Circular | 0.800 | 0.0130 |
Link-16 | 49 | 48 | 147.99 | 29.53 | 28.56 | 0.6600 | Circular | 0.800 | 0.0130 |
Link-17 | 48 | 47 | 172.95 | 28.56 | 27.60 | 0.5600 | Circular | 0.800 | 0.0130 |
Link-18 | 47 | 46 | 158.96 | 27.60 | 26.64 | 0.6000 | Circular | 0.800 | 0.0130 |
Link-19 | 46 | 45 | 121.96 | 26.64 | 26.56 | 0.0700 | Circular | 0.800 | 0.0130 |
Link-21 | 81 | 80 | 144.80 | 21.00 | 20.61 | 0.2700 | Circular | 0.500 | 0.0130 |
Link-22 | 82 | 81 | 147.50 | 22.18 | 21.00 | 0.8000 | Circular | 0.500 | 0.0130 |
Link-23 | 83 | 82 | 163.01 | 24.30 | 22.18 | 1.3000 | Circular | 0.500 | 0.0130 |
Link-24 | 45 | 83 | 178.12 | 26.67 | 24.30 | 1.3300 | Circular | 0.500 | 0.0130 |
Link-25 | 27 | 25 | 299.89 | 39.98 | 37.28 | 0.9000 | Circular | 0.400 | 0.0130 |
Link-26 | 25 | 28 | 121.37 | 37.28 | 36.66 | 0.5100 | Circular | 0.400 | 0.0130 |
Link-27 | 28 | 24 | 223.66 | 36.66 | 36.24 | 0.1900 | Circular | 0.400 | 0.0130 |
Link-28 | 29 | 23 | 125.55 | 36.24 | 35.24 | 0.8000 | Circular | 0.400 | 0.0130 |
Link-29 | 23 | 53 | 150.60 | 34.84 | 34.30 | 0.3600 | Circular | 0.400 | 0.0130 |
Link-30 | 53 | 52 | 195.63 | 34.25 | 32.45 | 0.9200 | Circular | 0.400 | 0.0130 |
Link-31 | 52 | 51 | 158.98 | 32.51 | 32.15 | 0.2300 | Circular | 0.600 | 0.0130 |
Link-32 | 51 | 54 | 262.46 | 32.15 | 30.20 | 0.7400 | Circular | 0.600 | 0.0130 |
Link-33 | 54 | 50 | 63.40 | 30.20 | 29.67 | 0.8400 | Circular | 0.600 | 0.0130 |
Link-34 | 29 | 28 | 318.89 | 39.37 | 36.66 | 0.8500 | Circular | 0.400 | 0.0130 |
Link-35 | 22 | 21 | 191.18 | 40.72 | 38.47 | 1.1800 | Circular | 0.400 | 0.0130 |
Link-36 | 21 | 20 | 155.89 | 38.47 | 37.63 | 0.5400 | Circular | 0.400 | 0.0130 |
Link-37 | 20 | 19 | 150.16 | 37.63 | 37.14 | 0.3300 | Circular | 0.400 | 0.0130 |
Link-38 | 19 | 63 | 158.87 | 37.14 | 35.66 | 0.9300 | Circular | 0.400 | 0.0130 |
Link-39 | 63 | 53 | 187.24 | 35.66 | 34.21 | 0.7700 | Circular | 0.400 | 0.0130 |
Link-40 | 13 | 14 | 189.79 | 40.13 | 38.53 | 0.8400 | Circular | 0.400 | 0.0130 |
Link-41 | 14 | 15 | 137.19 | 38.53 | 37.91 | 0.4500 | Circular | 0.400 | 0.0130 |
Link-42 | 15 | 16 | 151.70 | 37.91 | 37.24 | 0.4400 | Circular | 0.400 | 0.0130 |
Link-43 | 16 | 65 | 158.32 | 37.24 | 36.35 | 0.5600 | Circular | 0.400 | 0.0130 |
Link-44 | 65 | 63 | 196.11 | 36.35 | 35.66 | 0.3500 | Circular | 0.400 | 0.0130 |
Link-45 | 12 | 17 | 147.59 | 39.27 | 38.41 | 0.5800 | Circular | 0.400 | 0.0130 |
Link-46 | 17 | 18 | 199.19 | 38.41 | 37.05 | 0.6800 | Circular | 0.400 | 0.0130 |
Link-47 | 18 | 79 | 100.75 | 37.05 | 36.77 | 0.2800 | Circular | 0.400 | 0.0130 |
Link-48 | 79 | 65 | 189.60 | 36.77 | 36.35 | 0.2200 | Circular | 0.400 | 0.0130 |
Link-49 | 4 | 3 | 194.71 | 38.44 | 38.23 | 0.1100 | Circular | 0.400 | 0.0130 |
Link-52 | 7 | 8 | 187.55 | 36.58 | 36.09 | 0.2600 | Circular | 0.400 | 0.0130 |
Link-53 | 8 | 9 | 157.08 | 36.09 | 35.70 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-54 | 9 | 10 | 161.77 | 35.70 | 35.29 | 0.2500 | Circular | 0.400 | 0.0130 |
Link-55 | 10 | 11 | 201.13 | 35.29 | 34.64 | 0.3200 | Circular | 0.400 | 0.0130 |
Link-56 | 11 | 1 | 262.66 | 34.64 | 31.97 | 1.0200 | Circular | 0.600 | 0.0130 |
Link-57 | 1 | 77 | 137.99 | 31.97 | 31.72 | 0.1800 | Circular | 0.600 | 0.0130 |
Link-58 | 77 | 76 | 117.99 | 31.72 | 31.56 | 0.1400 | Circular | 0.600 | 0.0130 |
Link-59 | 76 | 74 | 114.99 | 31.56 | 31.50 | 0.0500 | Circular | 0.600 | 0.0130 |
Link-60 | 74 | 71 | 120.99 | 31.50 | 31.20 | 0.2500 | Circular | 0.600 | 0.0130 |
Link-61 | 68 | 71 | 117.99 | 31.18 | 31.23 | -0.0400 | Circular | 0.600 | 0.0130 |
Link-62 | 68 | 67 | 136.29 | 31.23 | 30.98 | 0.1800 | Circular | 0.600 | 0.0130 |
Link-63 | 67 | 54 | 212.99 | 30.98 | 30.20 | 0.3700 | Circular | 0.600 | 0.0130 |
Link-64 | 75 | 74 | 115.00 | 32.97 | 31.50 | 1.2800 | Circular | 0.400 | 0.0130 |
Link-65 | 73 | 72 | 126.50 | 34.14 | 32.37 | 1.4000 | Circular | 0.400 | 0.0130 |
Link-66 | 72 | 71 | 103.37 | 32.37 | 32.13 | 0.2300 | Circular | 0.400 | 0.0130 |
Link-67 | 70 | 69 | 129.81 | 33.33 | 32.36 | 0.7500 | Circular | 0.400 | 0.0130 |
Link-68 | 69 | 68 | 120.96 | 32.36 | 31.18 | 0.9800 | Circular | 0.400 | 0.0130 |
Link-69 | 66 | 67 | 251.86 | 32.12 | 30.94 | 0.4700 | Circular | 0.400 | 0.0130 |
Link-70 | 60 | 59 | 130.10 | 34.48 | 34.44 | 0.0300 | Circular | 0.400 | 0.0130 |
Link-71 | 59 | 58 | 103.60 | 34.44 | 34.38 | 0.0600 | Circular | 0.600 | 0.0130 |
Link-72 | 58 | 57 | 112.00 | 34.38 | 34.32 | 0.0500 | Circular | 0.600 | 0.0130 |
Link-73 | 57 | 56 | 115.00 | 34.32 | 34.28 | 0.0300 | Circular | 0.600 | 0.0130 |
Link-74 | 56 | 55 | 124.00 | 34.28 | 34.24 | 0.0300 | Circular | 0.600 | 0.0130 |
Link-75 | 55 | 53 | 98.99 | 34.24 | 34.21 | 0.0300 | Circular | 0.600 | 0.0130 |
Link-76 | 3 | 7 | 317.33 | 38.06 | 36.58 | 0.4700 | Circular | 0.400 | 0.0130 |
The climate in Karbala is described as cold in winter (below −41°F) and hot in summer (above 131°F) [
Average monthly rainfall and temperature in the study area for the years 1980–2013 adapted from Weather Forecast for Karbala [
As illustrated in Figure
Rainfall intensities for the three scenarios of the model [
The proposed methodology was first applied to the urban storm sewer systems in different municipalities of Karbala city based on the hydrology simulation and statistical data analysis. In this study, models based on actual hydraulic and hydrologic data were developed using Autodesk Storm and Sanitary Analysis (ASSA) [
The general method of approximation in nonlinear regression uses advanced, multiple-linear regressions that have been affected by logarithmic feature defects [
Model of the hypotheses model for the parameter ratios (3 scenarios).
For this study, the models were tested on three scenarios applied to the 121 most intense rainy season flood events in 2013 and rainfall data from 1980 to 2013. In the first scenario, there were 29 flooding events with an event frequency less than 0.042, and these ranged between 0.126 and 6.587 cms. In the second scenario, there were 39 flooding events with an event frequency less than 0.057, and these ranged between 0.429 and 15.232 cms. In the third scenario, there were 59 flooding events with an event frequency greater than 0.077, and the range was between 0.267 and 30.76 cms as shown in Figure
(a) Daily peak flooding based on three scenarios for available rainfall data (1980–2013). (b) Relationships between rainfall, runoff, and flooding over time for three scenarios of the model.
Normal and detrended P-P diagrams for all the parameters entered into the model.
The relationships among the parameters (
Normal and detrended Q-Q plots for all the parameters entered into the model.
Equations (
With the input of three values (minimum, average, and maximum) for each parameter (
The results of
Case |
|
|
|
|
|
|
---|---|---|---|---|---|---|
Minimum | 1.39 | 0.79 | 110621.23 | 0.004 | 0.01 | −5.74 |
Average | 53.35 | 0.75 | 141705.79 | 0.25 | 0.20 | 0.98 |
Maximum | 1276.00 | 5.36 | 802351.45 | 3.00 | 3.98 | 7.03 |
The optimal case of
Using logarithmic regressions, the correlations between parameters are reported in Table
Partial correlations for
|
|
|
|
|
|
|
---|---|---|---|---|---|---|
|
1.000 | −0.992 | 0.0128 | 0.287 | 0.136 | 0.182 |
|
−0.992 | 1.000 | 0.041 | −0.227 | −0.162 | −0.235 |
|
0.0128 | 0.041 | 1.000 | 0.448 | 0.576 | −0.062 |
|
0.2870 | −0.227 | 0.448 | 1.000 | 0.493 | 0.073 |
|
0.1360 | −0.162 | 0.576 | 0.493 | 1.000 | −0.118 |
|
0.1820 | −0.235 | −0.062 | 0.073 | −0.118 | 1.000 |
Correlations for all the parameters related to
The normality of the data was checked using the Kolmogorov–Smirnov test, and the empirical cumulative distribution function (CDF) for observation data is examined as shown in Figure
Empirical cumulative distribution function (CDF).
(a) Three model scenarios for
Regarding the calibration of the model, Figure
Model calibration of
All parameters determined during the process of calibration were used to validate the model, and the percent of difference is 2 (significant if less than 10) between observed and predicted data for
Three-dimensional surfaces of the model parameters.
One of the major challenges when designing a storm sewer system is identifying the likely impact of identified parameters at the planning stage in order to eliminate or mitigate frequency of flooding. Many storm sewer simulation models exist, but this study has attempted to find a more accurate way to examine the relationships between runoff discharge and storm pipe discharge, topography of subcatchment and network slope, velocity in subareas and velocity in storm pipe, size of urban areas and cross-sectional area of storm pipe. This numerical study was carried out to determine which factor was more important based on the equations developed in the model. Conclusions drawn from this model include the following: The computed water stage (7.03 This model can be used to predict flooding in urban areas and to estimate the percentage of storm networks needed in subcatchments to limit city flooding. The calculations suggest that the use of irregular classifications of rainfall data could increase the computational complexity essential to rebuild the model and significantly increase the time required for simulation runs. In compensation, the relationship between parameters entered into the model was logarithmic, and the distribution of data is nonlinear. This study recommends that the design and analysis procedure for a storm sewer system must include the mitigation of the risk flooding in urban areas.
These results may simplify developments in the prediction of urban flooding and thus protect resources as well as reduce flood risk. Given that storm sewer systems have historically been designed to consider limited rainfall intensity, this model can allow for varying rainfall intensities in unusual situations. The model has also established a clearer relationship between relevant parameters. It may therefore be useful worldwide in a range of different scenarios.
The author declares that there are no conflicts of interest regarding the publication of this paper.