HYDROLOGICAL PERFORMANCE OF THE GREEN ROOF AT SYRACUSECOE

Transcription

1 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

2 OUTLINE BACKGROUND INFORMATION AND SITE DESCRIPTION EXTENSIVE GREEN ROOFS INTENSIVE GREEN ROOFS OBJECTIVE METHODS AND EXPERIMENTAL SET UP RESULTS CONCLUSIONS QUESTIONS

3 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)

4 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.

5 CENTER OF EXCELLENCE ROOF 727 East Washington Street, Syracuse NY ( N, W) Wet & bulk collection Reference roof 15% 1% Vegetated roof

6 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.

7 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 PRECIPITATION INPUTS WERE RECORDED IN REAL TIME WITH HOBO U30 DATA LOGGER. Climatronics 6-inch tipping bucket precipitation gauge

8 METHODS AND EXPERIMENTAL SET UP

9 EXPERIMENTAL SET UP - LOWER PIPES

10 WATER STORAGE CAPACITY > 95% 83-95% < 83% 14 Total discharge x 10 3, L n =207, R 2 =0.93, P < THE GREEN ROOF HAS CAPACITY TO COMPLETELY RETAIN RAIN EVENTS LESS THAN 0.1 INCHES Total rainfall x 10 3, L

11 data Simulated event (A) Discharge per area, mm R 2 = 0.75, p<0.001 AREAL DISCHARGE (A) AND PERCENT RETENTION (B) IN THE GREEN ROOF AS A FUNCTION OF TOTAL PRECIPITATION 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 data Simulated event R 2 =0.65, p< Total rainfall, mm

12 GREEN ROOF WATER STORAGE CAPACITY RAIN EVENTS BETWEEN JANUARY AND END OF JULY, 2013 Volume of water, L /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, % Retention, % AVERAGE WATER RETENTION BETWEEN 2010 AND ±3%

13 WINTER - WATER BALANCE (IN LITERS) WINTER Dec 27, rain event WINTER Feb 01, rain event

14 SUMMER - WATER BALANCE (IN LITERS) HOT SUMMER DAY June 22, rain event HOT SUMMER DAY July 6, rain event ,

15 HIGH INTENSITY - WATER BALANCE (IN LITERS) HIGH INTENSITY RAIN EVENT EXPERIMENT June 6, rain event July 20,

16 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

17 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%