Reference no: EM132675397
49255 Catchment Modelling - University of Technology Sydney
A study is to be undertaken to assess the water quality in Homebush Bay. As part of this study, a stormwater quality model has been developed for the 8km2 Powells Creek catchment which drains into Homebush Bay. The basis of this stormwater quality model is the US EPA SWMM software.
The SWMM model uses a non-linear reservoir model for surface runoff (pond model) with a kinematic model for flowss in the channel. Water quality simulation is based on simulation of the EMC (event mean concentration) rather than a pollutograph or loadograph; this means that the focus of the water quality simulation is on prediction of the total mass of contaminant transported during the storm event
At present only the flow quantity component of the model is being calibrated. A milestone for the study is production of a suitable water quantity model.
The water quality component of the model is yet to be developed. Data available for use in the calibration are:
1. Rainfall data
a. 2 pluviometers (i.e. continuous rain gauges) within the catchment;
b. 6 pluviometer adjacent to the catchment
c. 1 daily read gauge within the catchment and another 6 in close proximity to the catchment;
d. Radar images of rainfall over the catchment; these images have not been processed, (i.e. converted to rainfall depths) but they are available for the study. The resolution of these radar images is 1 km x 1 km.
2. Catchment data
a. SRTM and LIDAR based models of the topography;
b. Detailed plans of the stormwater system in the catchment (note that the catchment is serviced by separate stormwater and sanitary sewer systems);
c. Detailed maps in GIS format of land use in the catchment (note that the whole catchment is urbanised);
d. Soil Maps of the catchment derived from the National Soil Survey
e. Gauged data at one site in the catchment for 49 years. There are some concerns about the rating curve at this gauge station for higher flows; this concern arises from the proximity of railway culverts and the potential for the station to be drowned during higher flows. This gauging station is located in the upper reaches of the catchment and monitors only 2.4km2 of the catchment.
In the attached file, details of calibration simulations are provided. Data included in the file for each event (there are multiple events in the file) are:
• Rainfall records from the pluviometer located at the catchment outlet;
• Recorded flow for the event;
• Predicted flows for alternative sets of parameter values.
Part A
i) Select and justify a calibration metric suitable for use to assess the calibration of the quantity component of the model;
ii) Apply this metric to the available data in a manner where all events are considered concurrently. You will need to consider how the different events can be combined and to justify this approach;
iii) Select and justify the best parameter set to be used with the water quality component of the model.
Part B
Briefly discuss the following:
i) How the different conceptual components of a catchment model would be used in developing this model.
ii) The sources of error in predictions obtained from a catchment model with reference to the current study. How should knowledge of these errors be considered in the current application.
iii) Whether the selected parameter values would change if a kinematic wave model were to be used in lieu of the non-linear reservoir model of surface runoff.
Part C
You have been asked to improve the current catchment model. To achieve that improvement, you have time and resources available. What would you do?
Attachment:- Catchment Modelling.rar
Attachment:- Data.rar