Stream temperature impacts due to stormwater runoff

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1 Stream temperature impacts due to stormwater runoff February 17, 2011 Jennifer M. Jacobs, Alison Watts, and Robert Roseen Students: Erik Carlson, Robert Nickerson, Sarah Kissell, Cherie Caputo, and Sam Despins Environmental Research Group UNH Stormwater Center Department of Civil Engineering University of New Hampshire In Partnership With D. Truslow, N. DiGennaro, G. Lemay, UNH; Ralph Abele, USEPA Region I; M. Carpenter, NHFG; D. Neils, NHDES NSF ADVANCE, USEPA TMDL, USGS WRI Funding

2 Thermal Regime and Water Quality Fish Species Preference Coldwater: 18oC (65oF) Cool (Mixed) Water Warm Water: 22oC (72oF) Upper Lethal Temp 25-30oC (77-86oF) Dissolved Oxygen Inverse relationship between DO and temperature Warm water may cause the fish's DO demand to increase. Photosynthesis Cool waters slow the growth of bacteria and algae Warm water enhances algal growth Water Chemistry Increased plant growth can decease DO Increasing temperature decreases ph Water Turbidity and Sediment Loads Aquatic Organisms Species abundance and diversity Coldwater species include mayflies, caddisflies Timing of reproduction, migration and aestivation Pictures Credit: Bluegreen bloom, Upper Saranac Lake, 10/90 (source: R. Handler, MD) Pictures Credit: NJ Freshwater Fish Identification

3 Does stormwater runoff impact stream temperature? What have we observed?

4 Fiber Optic Survey July 15 to Sept 9, 2009 Hodgson Brook Baseflow Temperatures Flow Direction upstream downstream

5 Storm Event Storm Characteristics August 11, 2009 Time: 08:15 to 09:15 Air Temp: 21.3 o C Water Temp: 21.0 o C Rain: 1.6 cm 8/11/09 10:33 Flow Direction 8/11/09 Flow Direction 10:04 D a te /T im e 8/11/09 9:36 8/11/09 9:07 8/11/09 8:38 Rainfall Intensity (mm/hr) Solar Radiation (W/m 2 ) /11/09 8:09 8/11/09 7:40 8/11/09 7:12 upstream downstream

6 Wednesday Hill: A small 1 st order stream ~ 15 mins Rainfall Event Starts Downstream Upstream Culvert Location

7 How does stormwater runoff impact stream temperature? A mixing problem T Q + T Q = u u s s T d Q d

8 T Q + T Q = u u s s T d Q d Upstream T,Q Stormwater T,Q Downstream T,Q T T d d T Q + T Q = Tu Qu + Ts Qs = u u s Q Q + d Q u s s Further Downstream T,Q

9 What is the receiving water body flow and temperature? What is the stormwater runoff and temperature? What have we observed?

10 HTE Nov-07 Sep-07 Jul-07 A Coldwater Stream s Thermal Regime May-07 Mar-07 Jan-07 Nov-06 Sep-06 Jul-06 May-06 Mar-06 Jan-06 Nov-05 Sep-05 Jul Average Daily Temperature ( C)

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12 Stormwater Systems Retention Pond Detention Pond Veg Swale Gravel Wetland Bioretention Unit Subsurface Infiltration Hydrodynamic Separator Isolator Row 12

13 Summer Quartile Assessment LL Event Mean Temperature ( o F) UOL GW LOL Runoff Retention Pond Detention Pond Gravel Wetland Bioretention Vegetated Swale Hydrodynamic Separator ADS Infiltration System StormTech Isolator Row 13

14 Examination of Thermal Impacts from Stormwater BMPs: Conclusions Infiltration practices allow greater buffering of stormwater temperature. The longer subsurface flow paths and mass, the greater the buffering. Bioretention Gravel Wetland ADS Infiltration System Conventional stormwater management designs that include ponding as a control measure, allow for additional increase in temperature. Permanent pools of water act as heat sinks during the warmer summer months. Vegetated Swale Detention Pond Retention Pond 14

15 Does the stream have the capacity to buffer temperature loads?

16 Mixing Stream and Stormwater ΔT in o F (approximate change in stream temp) T =temperature Q = Flow U = upstream, D = downstream, S =stormwater 10% 20% 25% 30% 40% 50% 60% 70% 75% 80% 90% % Q stormwater/ 100% (Q upstream + Q downstream) EMT in o F (relative to stream temp) Event Mean Temperature (EMT) is the average temperature as weighted by streamflow

17 Chesley Brook Caldwell Brook Chesley July T = 58ºF (2010) Caldwell July T=60ºF

18 UNH Stormwater runoff July 14, 2010 EMT 73F

19 If runoff from a 1-acre parking lot drained into this stream what would happen? Chesley Brook T=58ºF, Stormwater T=73ºF Stream Q = 1000gpm, Stormwater flow=740gpm Stream T (downstream) = 64ºF (ΔT = 6ºF) Caldwell Brook T= 67ºF Stormwater T=73ºF Stream Q = 1000gpm, Stormwater flow=740gpm Stream T (downstream) = 69.5ºF (ΔT = 2.5ºF) Caldwell Brook T= 67ºF Stormwater T=73ºF Stream Q = 370 gpm, Stormwater flow=740gpm Stream T (downstream) = 69.5ºF (ΔT = 4ºF)

20 Goal: Have the capacity to design required BMP characteristics (ie type and size) to be protective for receiving waters Approach: Develop and combine predictive thermal energy balance models for streams and stormwater BMPs

21 Designing BMPs to Mitigate Temperature

22 Energy Balance Modeling Solar Measured Stormwater Pond Conduction Temperature (water and soil), thermal conductivity Evaporation/condensation Air temperature, density of water, vapor pressure (water and air) Convection Atmospheric pressure, temperature (water and air), emissivity (water and air) Longwave radiation Air temperature, emissivity (water and air) Influent (Q i T i ) Efffluent (Q o T o ) Hyporheic Flux Rate of flux, water temperature

23 Influent Inputs Effluent Evaporation = Influent Temperature = 15 C Heat(in)= J Longwave Radiation (in) =7.83E 13 Total inputs = J Longwave Radiation (out) =1.1E 12 Energyi(i n)= J Convective Energy Flux =0 Effluent Temperature = C Mw= g Hyporheic Flux =0 Solar = Vol w = 1000 cf Conduction =0 T w = 15 C Total = cm 3 per ft 3

24 Construction Factors Heat inputs are a function of energy/area/time Solar radiation Longwave radiation Evaporation Convection Conduction Hyporheic exchange Surface area, shade Surface area, exterior T(depth) Surface area, shade? Surface area Subsurface area, depth, lining Lining material

25 Energy Balance Modeling for Streams 25

26 Temperature change per 100 meters due to heat flux source( o C/ 100 m) Energy Budget WHB Study Reach Reach 1 Reach 2 Net Radiation Evaporation Reach 3 Convection Friction Reach 4 Streambed Conductance Hyporheic exchange Groundwater Inflow Tributary Discharge Reach 5 Reach 6 Reach 1a Reach 2a

27 Temperature Change as a function of Energy Input and Streamflow

28 Approach: Use simple stream and weather data to estimate Heat Loss or Gain 28

29 Designing BMPs to Mitigate Stream Temperature Impact Step 1. Develop simple box models for pond, bioretention and gravel wetland, validate with UNHSC data Step 2. Develop energy balance model of streams and combine with stream temperature datasets to predict baseline temperature Step 3. Combine model output with stream characteristics to predict impact of BMPs (as constructed at UNHSC) Step 4. Refine models to include construction options, and more accurate thermal model (layering, unsteady state) Step 5. Develop decision support module for use in designing BMPs for thermal impact

30 Thank You Questions & Discussion Jennifer M. Jacobs, Alison Watts, and Robert Roseen Project partners UNH Stormwater Center, CICEET, USEPA Region1, NSF ADVANCE, USGS WRI, Coastal Training Program Great Bay NERR