Storm System Modeling

Many communities are frequently faced with the problem of urban expansion impacting aging and undersized storm drainage systems leading to flooding. Storm flooding brings with it many undesirable consequences such as increased sanitary sewer I/I leading to basement “back-ups” and flooding. In order to adequately resolve the problems associated with deficient storm handling capability, it is necessary to obtain a comprehensive understanding of the system behavior and performance.

One method to obtain such understanding is developing a mathematical model of the system. There are several advantages to using mathematical model over the conventional method of long term flow monitoring coupled with statistical analysis of rainfall data. It is more economical, time saving, and more accurate. It also provides more flexibility of analysis and can be modified to adjust to changing environmental conditions.

What can a Model do for You?

A model can assist the community in development of management strategies that can reduce the impact of flooding while minimizing the resources to do so – optimization. Proper management strategies will ultimately ameliorate flooding impacts such as:

  • Transportation systems problems and traffic delays
  • Basement flooding due to increase I/I of sanitary systems due to flooding
  • Damage to public and personal properties
  • Combined sewer overflows
  • Health hazards
  • Disruption of services such as water supply
  • Cost of “after-flood” cleanups, etc.

The model can also assist the community with planning and design, sewer rehabilitation, and analyzing “what if” scenarios prior to construction.

Storm Sewer Model Components

A storm sewer model has two main components; hydrologic (rainfall/run-off) and hydraulic (transport/drainage system). Traditionally, estimating runoff had been relegated to approximating peak discharges based on empirical formulas. However, with the advent of digital computers, more accurate estimates of runoff is obtained by incorporating complex time-dependent rainfall intensity.

The complexity of storm sewer model should be tailored to data availability and the objective that the client wishes to obtain. Jones & Henry personnel have extensive experience in developing models using numerous software to meet the client’s expectation. One such software is the EPA’s Storm Water Management Model (SWMM), which is perhaps, the best known and most used worldwide software for storm and sewer modeling. Most commercial software available on the market is based on the EPA’s SWMM model.

This software has a graphical user interfaces that allow ease of data input and verification, thereby reducing the possibility of errors. If desired, tabular input is also available. Likewise, data output can also be accomplished by means of both tabular and graphical interface.

Ways in Which Jones & Henry Can Assist You

Jones & Henry can assist you in your storm water management strategies to achieve the most efficient expenditure of capital resources to improve urban drainage in your community. Specific activities in which we can assist you include:

  • Model development
  • Flow monitoring for model calibration
  • Identifying deficiencies in the drainage system
  • Proposing strategies for improvement
  • Developing prioritized list of improvement
  • Providing cost estimates for improvements
  • Training owner employees in the use of the modeling software
Jones & Henry
Engineers, Ltd.