Transcript Tongren Zhu
Rainwater Harvesting using 3D roofs in Corpus Christi, Texas By Tongren Zhu Dec. 20th,2012 Rainwater Harvesting Definition Rainwater harvesting is the accumulation and storage of rainwater for reuse before it reaches the aquifer. Uses Including water for garden, water for livestock, water for irrigation, cleaning of bathrooms as in first flush, etc. Benefit Provide sufficient water supply, serve as a valuable stormwater management tool. Corpus Christi Fifth largest US port, with an unemployment of 6.6% and annual GDP growth of 3.1% With a population of 305,215 according to 2010 census, 10% increase since 2000 Growing needs for water, but declining supply from reservoir Growing Demands & Declining Supply Additional Source of Water Needed！！！ Lake Corpus Christi Reservior http://www.nueces-ra.org/CP/CITY/day.php http://corpuschristi.usgulf.info/Level.asp Project Area 237 buildings in total All commercial buildings in downtown With field value of roof areaXY, facade area, reletive height, roof slope etc. Will look into potential of rainwater for toilet use Calculation of Toilet Water Needs Toilet: 6L(1.6 gallon) per flush Urinal: 3.8L(1 gallon) per flush Lavatory Faucet: 5.7L(1.5 gallon) per minute Assume 10 hours in the office per day For male, use toilet 1 time, use urinal 4 times, 21.2L/(cap-day) For female, use toilet 5 times,30L/(cap-day) For one capita, 25.6L/day. We use 30L/day here. 30L/(Cap-d) Calculation for water Needs Parameters set: 4.5m/floor, 25m2/cap Capita in Building OfficeArea 0.9RoofAre aXY Story 0.9RoofAre a RelativeHe ight/4.5 25m 2 /cap 25m 2 /cap 25m 2 /cap Water Needs in Building=30L/(cap-day)×Capita For Some special buildings, area are remeasured. Month Toilet Water Needs in Each Building Rainwater Captured • Precipitation Data • Rainwater Captured =Precipitation× Roof AreaXY×0.85 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Median 0.99 1.36 0.78 1.39 2.70 2.43 1.04 2.64 4.00 2.60 1.34 0.90 Average 1.54 1.85 1.36 2.03 3.12 3.16 1.80 3.28 5.21 3.50 1.57 1.59 Month Balance Calculation End of Month=End of Previous Month+Rainwater Captured this month-Water Used this month In the case of ObjectID=1 building: To ensure water supply, the lowest End of Month Storage value(-1.021m3)×Safety Factor(1.5) should be considered the smallest tank volume which is filled in the beginning. Here, we choose 1.5m3. If tank volume larger than this value, rainwater captured can be put into other use in addition to toilet flush. Month Balance Calculation End of Month=End of Previous Month+Rainwater Captured this month-Water Used this month In the case of ObjectID=15 building: To ensure water supply, the lowest End of Month Storage value(-2128.5m3) ×1.5 should be considered the smallest tank volume which is filled in the beginning. This value is wierd!!! So for tall buildings with comparatively small roof area, rainwater cannot be the only source for toilet flush water. Other source is water is still needed and rainwater harvest system under such case acts more like a demonstration project. Feasibility • • • Usually, a tank volume of 50m3(13,000gallon) is considered as the threshhold for feasibility. For buildings occupy large area(>500m2), a tank volume of 100m3(26,000gallon) is considered as the threshhold for feasibility. For buildings occupy a very large area(>1000m2), a tank volume of 150m3(39,000gallon) is considered as the threshhold for feasibility. For those lacking feasibility now, more specific work is needed when checking rainwater harvesting potential. Conclusion • Corpus Christi is enjoying steady population and economy growth which may lead to more water consumption • Reserviors for Corpus Christi is declining, meaning new source of water is needed • For buildings with large roof areas and fewer stories, rainwater harvested has great potantial. • For skyscrapers, rainwater might work for some specific use, or be used above a certain floor which needs more detailed consideration under given project. Reference & Acknowledge The Texas Manual on Rainwater Harvesting, Texas Water Development Board, Third Edition,2005,Autin, Texas Nueces River Authority website http://www.nueces-ra.org/CP/CITY/day.php USEPA WaterSense website http://www.epa.gov/WaterSense/index.html City of Corpus Christi website http://www.cctexas.com/ ArcGIS online basemap CyberCity3D Dr. Maidment, Dr. Tarboton and Dr. Kilic All GIS in Water Resources classmates Thank You !