Role of Urban Runoff in Harmful Algal Bloom Formation in the Western Lake Erie Basin

Bernard Bahaya REU Graduate Mentor,Advisor; Cyndee Gruden PhD P.E

Motivation• In August of 2014, The City of Toledo experienced an

interruption in the provision of safe drinking water due to harmful algal bloom (HAB) formation in the western lake erie basin (WLEB). • Several factors contributing to HAB formation have been

identified: the disposition of nutrients and suspended solids to Lake Erie from the surrounding watersheds.

Role of imperviousness

Motivation and aim of the research.• Increased imperviousness reduction in surface water

quality.

• The goal: How Imperviousness affects the concentration of TSS in the WLEB.

Total Suspended Solids (TSS)• TSS : particles > 2 µm. [1, 2]

• EMC : 180 – 548 mg/L in stormwater. [4,5]

• TSS change : light penetration in the surface water HAB forming bacteria.

Methods• ISAT : used to calculate and allocate the Mean

Imperviousness coefficients.

(Dietrich 2014)

Methods: Hydrologic Unit Codes• System used by USGS: (sub)divides the US: smaller

hydrologic units. [3]

watershed boundary dataset

Further divides the HUC levels to (5th and 6th levels) and includes the most recent 10 and 12 digit HUC classification [3]

A map showing the location of the HUC-12 – MS4 contributing watersheds.

SWMM• EPA's Storm Water Management Model (SWMM) is used

throughout the world for planning, analysis and design related to storm water runoff, combined and sanitary sewers, and other drainage systems in urban areas. [6, 8, 9]

• Provides solutions to a series of mathematical expressions using built in computer code. [10]

SWMM models clip

equal area, compare

Results: Comparing the TSS loading.

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 500.0E+00

5.0E+06

1.0E+07

1.5E+07

2.0E+07

2.5E+07

30 by 30 DEM, 300ac discretization

Clipped DEM, 300ac discretization

Percent change in Imperviousness

TSS

load

ing

of th

e sy

stem

(mg)

Results: Comparing the total volume of runoff.

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 500.0E+00

5.0E+07

1.0E+08

1.5E+08

2.0E+08

2.5E+08

3.0E+08

3.5E+08

30 by 30 DEM, 300ac discretization

Clipped DEM, 300ac discretization

Percent change in Imperviousness

Tota

l Vol

ume

(L)

Discussion• Longer flow lengths in the 30 by 30 DEM capture more TSS

loading.• Shorter conduit lengths, in the 30 by 30 DEM water was not

lost by other factors – evaporation.• For both SWMM models, it was seen that the increase in

imperviousness increased TSS loading and runoff volume. This was in agreement with other researchers’ findings. [11]

Conclusion• The resolution of the model needs to be considered since it

affects the estimation of TSS loads to Lake Erie. It increases by ½ order of magnitude which is very significant: 10 by 10 DEM

Acknowledgements.• Dr. Cyndee Gruden Professor of Civil Engineering, the department of

Civil Engineering at University of Toledo.•Mr. Muthana Al-Quraishi PhD candidate, the department of Civil

Engineering at University of Toledo.

References;1. Turbidity, Total Suspended Solids & Water Clarity - Environmental Measurement Systems. July 15 2016]; Available from:

http://www.fondriest.com/environmental-measurements/parameters/water-quality/turbidity-total-suspended-solids-water-clarity/#Turbid1.

2. TOTAL SUSPENDED SOLIDS. July 15 2016]; Available from: https://www.ndhealth.gov/WQ/SW/Z6_WQ_Standards/WQ_TSS.htm.

3. Hydrologic Unit Maps. July 15 2016]; Available from: http://water.usgs.gov/GIS/huc.html.

4. Huber, W.C., Urban rainfall-runoff-quality data base: addendum I: statistical analysis and additional data. 1981, EPA-600/2-81-238, US Environmental Protection Agency, Cincinnati, Ohio.

5. USEPA, Results of the nationwide urban runoff program. 1983, Water Planning Division Washington, DC.

6. Cambez, M., J. Pinho, and L. David. Using SWMM 5 in the continuous modelling of stormwater hydraulics and quality. in 11 th International Conference on Urban Drainage, Edinburgh, Scotland, UK. 2008.

7. Hossain, I., M.A. Imteaz, and M.I. Hossain, Application of build-up and wash-off models for an East-Australian catchment. Int J Civil Environ Eng, 2011. 3(3): p. 156-161.

8. Storm Water Management Model (SWMM). [cited July 18th 2016; Available from: https://www.epa.gov/water-research/storm-water-management-model-swmm.

9. Temprano, J., et al., Stormwater quality calibration by SWMM: A case study in Northern Spain. water SA, 2007. 32(1): p. 55-63.

10.James, W., Rules for Responsible Modeling. 4th ed. 2005, Guelph, Ontario, Canada: CHI (Computational Hydraulics International).

11.Barco, J., K.M. Wong, and M.K. Stenstrom, Automatic Calibration of the U.S. EPA SWMM Model for a Large Urban Catchment. Journal of Hydraulic Engineering, 2008. 134(4): p. 466-474.

Thank you! Any questions?