HYDROLOGICAL PERFORMANCE OF THE GREEN ROOF AT SYRACUSECOE DIMITAR TODOROV 1,2 AND CHARLES DRISCOLL 2 1 UTICA COLLEGE, UTICA NY 2 SYRACUSE UNIVERSITY, SYRACUSE, NY
OUTLINE BACKGROUND INFORMATION AND SITE DESCRIPTION EXTENSIVE GREEN ROOFS INTENSIVE GREEN ROOFS OBJECTIVE METHODS AND EXPERIMENTAL SET UP RESULTS CONCLUSIONS QUESTIONS
BACKGROUND GREEN ROOFS CONSIST OF A LAYER OF VEGETATION AND SOIL INSTALLED ON TOP OF A CONVENTIONAL FLAT OR SLOPED ROOF. THE ROOFTOP VEGETATION CAPTURES RAINWATER ALLOWING EVAPORATION AND EVAPOTRANSPIRATION PROCESSES TO REDUCE THE AMOUNT OF RUNOFF ENTERING DOWNSTREAM SYSTEMS, EFFECTIVELY REDUCING STORMWATER RUNOFF VOLUMES AND ATTENUATING PEAK FLOWS. EXTENSIVE (FLAT OR SLOPED ROOFS, 2-4 MEDIA DEPTH) INTENSIVE (FLAT ROOFS, > 4 MEDIA DEPTH)
EXTENSIVE ROOFS Vegetated roof components (LIDC) ROOF STRUCTURE SUPPORTS THE GREEN ROOF SYSTEM AND ANY LIVE LOADS. WATERPROOFING BARRIER A LAYER TO PROTECT THE ROOF STRUCTURE. DRAINAGE LAYER - POROUS MEDIA CAPABLE OF WATER STORAGE FOR PLANT UPTAKE AND STORM BUFFERING. GEOSYNTHETIC LAYER MEMBRANE PREVENTING THE FINE SOIL MEDIA FROM CLOGGING THE POROUS MEDIA. GROWING MEDIUM. PLANTS SELECTION TO MATCH THE ROOF TYPE.
CENTER OF EXCELLENCE ROOF 727 East Washington Street, Syracuse NY (43 3 00 N, 76 8 28 W) Wet & bulk collection Reference roof 15% 1% Vegetated roof
OBJECTIVE WHAT IS THE FATE OF PRECIPITATION INPUTS TO THE EXTENSIVE GREEN ROOF AT SYRACUSE COE AND HOW DOES IT VARY WITH EVENT INTENSITY? THE FOCUS OF THIS PRESENTATION WILL BE ON WATER QUANTITY.
METHODS AND EXPERIMENTAL SET UP PRECIPITATION QUANTITY WAS DETERMINED USING A CLIMATRONICS 6-INCH TIPPING BUCKET PRECIPITATION GAUGE. WATER QUALITY DATA WAS COLLECTED FROM SEPTEMBER 2010 TO SEPTEMBER 2013. PRECIPITATION INPUTS WERE RECORDED IN REAL TIME WITH HOBO U30 DATA LOGGER. Climatronics 6-inch tipping bucket precipitation gauge
METHODS AND EXPERIMENTAL SET UP
EXPERIMENTAL SET UP - LOWER PIPES
WATER STORAGE CAPACITY > 95% 83-95% < 83% 14 Total discharge x 10 3, L 12 10 8 6 4 2 2010-2013 n =207, R 2 =0.93, P < 0.0001 THE GREEN ROOF HAS CAPACITY TO COMPLETELY RETAIN RAIN EVENTS LESS THAN 0.1 INCHES 0 0 10 20 30 40 50 Total rainfall x 10 3, L
2.5 2012 data Simulated event (A) Discharge per area, mm 2.0 1.5 1.0 0.5 R 2 = 0.75, p<0.001 AREAL DISCHARGE (A) AND PERCENT RETENTION (B) IN THE GREEN ROOF AS A FUNCTION OF TOTAL PRECIPITATION 0.0 0 5 10 15 20 QUANTITY (IN MM). Total rainfall, mm 100 (B) RESULTS FROM THE ARTIFICIAL IRRIGATION ARE SHOWN WITH OPEN CIRCLES. THE 95 REGRESSION RELATIONSHIP EXCLUDES THE Retention, % 90 ARTIFICIAL IRRIGATION EXPERIMENT. 85 2012 data Simulated event R 2 =0.65, p<0.0001 80 0 5 10 15 20 25 Total rainfall, mm
GREEN ROOF WATER STORAGE CAPACITY 50000 100 RAIN EVENTS BETWEEN JANUARY 40000 90 AND END OF JULY, 2013 Volume of water, L 30000 20000 10000 0 1/29/2013 1/30/2013 1/31/2013 4/19/2013 5/8/2013 5/10/2013 5/11/2013 5/23/2013 5/24/2013 5/28/2013 6/6/2013 6/7/2013 6/8/2013 6/10/2013 6/11/2013 6/16/2013 6/17/2013 6/18/2013 7/5/2013 7/6/2013 7/7/2013 7/9/2013 7/10/2013 7/20/2013 7/23/2013 7/27/2013 7/28/2013 Total rainfall, L Total discharge, L Retention, % 80 70 60 50 Retention, % AVERAGE WATER RETENTION BETWEEN 2010 AND 2013 95±3%
WINTER - WATER BALANCE (IN LITERS) WINTER Dec 27, 2011 0.2 rain event 4767 255 WINTER Feb 01, 2012 0.1 rain event 2383 556 4361 1812 151 15
SUMMER - WATER BALANCE (IN LITERS) HOT SUMMER DAY June 22, 2011 0.8 rain event 19067 1313 HOT SUMMER DAY July 6, 2013 0.1 rain event 2053 4,322 15566 2188 11
HIGH INTENSITY - WATER BALANCE (IN LITERS) HIGH INTENSITY RAIN EVENT EXPERIMENT June 6, 2013 1.7 rain event 40517 July 20, 2013 18246 366 2339 29673 13972 10478 1953
CONCLUSIONS THE GREEN ROOF AT SYRACUSE COE IS ABLE TO EFFECTIVELY RETAIN INPUTS OF WATER ASSOCIATED WITH PRECIPITATION EVENTS, ALTHOUGH THE RATE OF WATER RETENTION DECREASES WITH LARGER PRECIPITATION EVENTS. THE SYRACUSE COE GREEN ROOF ACHIEVES AN AVERAGE RETENTION OF 95±3%. UP TO 96% STORMWATER RETENTION FOR RAIN EVENTS WITH INTENSITY < 0.2 IN/DAY BELOW 80% STORMWATER RETENTION WAS OBSERVED FOR RAIN EVENTS WITH INTENSITY > 1.0 IN/DAY THE LOWEST STORMWATER RETENTION OF 75% WAS OBSERVED DURING A 1.7-INCH/DAY RAIN EVENT
QUESTIONS Q1: WHAT IS THE MEDIA DEPTH OF A TYPICAL EXTENSIVE GREEN ROOF? A1: THE MEDIA DEPTH OF A TYPICAL EXTENSIVE GREEN ROOF US 2 TO 4. Q2: WHAT RAIN EVENTS ARE COMPLETELY RETAINED BY THE GREEN ROOF AT SYRACUSE COE? A2: THE GREEN ROOF AT SYRACUSE COE COMPLETE RETAINS RAIN EVENTS LESS THAN 0.1 INCHES. Q3: WHAT IS THE AVERAGE WATER RETENTION ACHIEVED BY THE BY THE GREEN ROOF AT SYRACUSE COE BETWEEN 2010 AND 2013? A3: THE AVERAGE WATER RETENTION BETWEEN 2010 AND 2013 WAS 95±3%