COURSEWORK BRIEFING SHEET
ASSIGNMENT TITLE: Hydrologic Modelling, Optimisation and Low Impact Development (LID) Practices Implementation in Matric City Drainage Area
Aims: To develop skills for performing hydraulic modelling and optimisation of an existing stormwater drainage system; To develop skills for use of the SWMM-LID model and evaluation of LID practices with respect to Sustainable Urban Drainage Systems (SUDS); To strengthen students’ further understanding of the role of LID practices in urban water management.
Details: See the following page for coursework details.
At the end of this assignment a student should be able to (Learning Outcome A, B):
• Develop an understanding of the hydraulic modelling techniques of stormwater drainage systems and their limitations.
• Develop critical thinking and apply theoretical concepts in the optimisation of the drainage system.
• Understand hydraulic and hydrological concepts for the design and optimization of LID practices in an urban area.
• Simulate rainfall-runoff modeling using the SWMM-LID model focusing on the impact of LID practices on runoff characteristics.
• Develop critical thinking and apply theoretical concepts in the selection of LID practices for effective water management in urban areas.
Recommended Reading
• Chaudhry, M. Hanif, Open‐Channel Flow (2nd Ed). Springer, 2007
• Chow, Ven Te, Applied Hydrology, McGraw‐Hill, 1988.
• Butler David, Davies John, Urban Drainage Systems, SPON, 2010.
• Colin Booth, Susanne Charlesworth, Water resources for the built environment management issues and solutions, John Wiley & Sons, 2014.
• Arup K. Sarma, Vijay P. Singh, Suresh A. Kartha, Rajib K. Bhattacharjya, Urban Hydrology, Watershed Management and Socio-Economic Aspects, Springer, 2016.
• Hormoz Pazwash, Urban storm water management (2ndEd), Taylor & Francis, 2016.
• Cahill, T.H., Low Impact Development and Sustainable Stormwater Management, Wiley, 2012.
• Novak, C.A., Van Giesen, G.E., DeBusk, K.M., Designing Rainwater Harvesting Systems, Wiley, 2014.
Drainage System
An urban area has been considered as the catchment area under study. The catchment consists of 16 building blocks, as shown in Figs. 1 and 2, discharging their runoff in the surrounding sewer system. The proposed sewer system runs underneath the major roads of the urban area as indicated by the green lines on the map of Fig. 1.
Fig. 1 Urban catchment and sewer system
The arrangement of the sewer systems is more analytically shown in Fig. 2. The system manholes are indicated with (M), while all building blocks contributing to runoff are indicated with (B). All pipe characteristics, sub-catchment slopes and invert levels of junctions are given in Table 1.
Fig. 2 Arrangement of the storm water sewer system
Table 1. Drainage system data (note invert levels are all 1.5 m below ground level)
The characteristics of each sub‐catchment are given in Table 2.
Table 2. Sub‐catchment characteristics
The design storm hyetograph can be derived by the following 15‐minute interval time series.
Table 3. Design storm hyetograph ordinates
Using the SWMM software, the data provided in Tables 1‐6 and the map of the drainage area, write a detailed report about the following:
1) Simulate, using the kinematic wave (KW) method, the response of the given drainage system to the given rainfall event. Provide a detailed account of the behaviour of the system by using this method. Analytically describe its limitations.
2) Improve your simulations and your network by using the full dynamic wave (DW) method. Provide a detailed account of the behaviour of the system by using this method. Analytically describe any differences in the response of the system in comparison to the KW. Provide an analytical mathematical/hydraulic description of the advantages of the DW compared to KW.
3) Optimise the drainage system in such a way that any flooding phenomena are completely eliminated or mitigated to a reasonable degree. The design optimisations need to be realistic and to follow the practical guidelines described in the “Sewers for Adoption” technical guide. Provide a detailed description of all possible impacts of your optimisation.
4) Simulation of rainfall-runoff modeling after the establishment of green roofs and pervious pavements among several LID practices (LIDs characteristics are shown in Tables 4-6), separately.
• Use the maximum possible areas for each LID practice.
• Remember to adjust the amount of impervious area in each sub-catchment according to the LID are used.
• Route as much runoff from remaining impervious areas onto the LID areas as practically possible.
• Route all runoff from LID and impervious area onto the pervious areas.
* Please describe the details of modeling works in the report.
5) Your analysis of runoff characteristics (e.g., total runoff volume, peak rate of runoff, etc.) before and after the establishment of LID practices.
* Please describe how you have routed the runoff from the different areas for each case.
6) Your analysis of runoff characteristics followed by different properties below:
• Surface layer properties (e.g., Manning’sn and surface slope);
• Pavement layer properties (e.g., thickness, porosity, and hydraulic conductivity);
• Storage layer properties (e.g., thickness, porosity, and seepage rate);
• Drainage mat properties (e.g., thickness, porosity, and Manning’s n).
* Please consider one of different properties and simply assume the specific values (two different values at the minimum) of each property.
7) Your discussion of findings focusing on advantages and disadvantages of LID practices (i.e.,
green roof and pervious pavement) in relation to the specific urban drainage area simulated.
Table 4. Green roof characteristics
Here, the buildings are 10 × 12 m with a width of 12 m.
Table 5. Pervious pavement characteristics (no underdrain)
Here, let us assume that 11% of the non-roof impervious area is composed of roads.
Table 6. Roof area percentage
Here, let us assume that 11% of the non-roof impervious area is composed of roads.
Notes:
1. Please use the following coordinates to adjust the map to its real dimensions in SWMM.
Lower Left X: 0.00 - Upper Right X: 494.1
Lower Left Y: 0.00 - Upper Right Y: 426.6