Why You Need a Storm System Model for your Storm Drainage System

Discover why using a mathematical storm system model is the best way to understand your storm drainage system and resolve flooding problems.

Posted on: February 15, 2018

Has your community been affected by flooding because of your storm drainage systems?

If so, this isn’t uncommon; in fact, for many communities, urban expansion impacts their aging and undersized storm drainage systems, leading to flooding.

And as you know, flooding brings many undesirable consequences with it such as increased sanitary infiltration/inflow (I/I), which gives rise to basement “back-ups”—and more flooding.

In order to adequately resolve the problems associated with deficient storm handling capability, it’s necessary to obtain a comprehensive understanding of the system behavior and performance.

One method to obtain such an understanding is to develop a mathematical model of your storm system.

Why Mathematical Models?

There are several advantages to using a mathematical model over the conventional method of long-term flow monitoring coupled with a statistical analysis of rainfall data.

To begin with, it is more economical, time-saving, and accurate.

Also, it provides more flexibility of analysis and can be modified to adjust to changing environmental conditions.

What Can a Storm System Model Do for You?

A model can help you develop your management strategies to reduce the impact of flooding while minimizing the resources to do so—or in other words, optimization.

Proper management strategies will ultimately ameliorate flooding impacts such as:

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

The model can also assist you with planning and design, sewer rehabilitation, and analyzing “What if?” scenarios prior to construction.

Storm Sewer Model Components

Storm sewer models have two main components: hydrologic (rainfall/runoff) 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 are obtained by incorporating complex time-dependent rainfall intensity.

Storm Water Management Model (SWMM)

The complexity of your storm sewer model should be tailored to data availability and the objective that you wish to obtain. Jones & Henry personnel have extensive experience in developing models using numerous software to meet our clients’ expectations.

One software we use 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 actually based on the EPA’s SWMM model.)

SWMM has 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 input can also be accomplished by means of both tabular and graphical interfaces.

Jones & Henry and Storm System Modeling

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.

Some specific activities we can help you with include:

  • Model development
  • Flow monitoring for model calibration
  • Identifying deficiencies in the drainage system
  • Proposing strategies for improvement
  • Developing prioritized list of improvements
  • Providing cost estimate for improvements
  • Training owner-employees in the using of modeling software

Have you used the EPA’s Storm Water Management Model (SWMM) in the past? Tell us about your experience.

Contact Jones & Henry

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