Download - Rainwater harvesting & irrigation
Rainwater Harvesting & Irrigation
Using Rainwater as a supplemental source of water for your landscape irrigation system
By Sean Mullarkey CID, CLIA, CIC, CGIA513.379-5780
What comes down goes around?
• Can we catch all the rain?
• Do we need all the rain?
• How can we use all the rain?
Cincinnati Weather
J an Feb Mar Apr May J un J ul Aug Sep Oct Nov Dec
Avg. High 38° 42° 54° 65° 75° 84° 86° 85° 78° 67° 54° 44°
Avg. Low 21° 24° 34° 44° 52° 61° 66° 64° 57° 44° 35° 26°
Mean 30° 34° 44° 54° 64° 72° 76° 75° 68° 56° 45° 35°
Avg. P r ecip. 2.50 2.50 4.30 3.70 4.40 3.40 4.10 3.70 3.10 2.80 3.30 3.10
Avg. E T 0.62 1.12 2.17 3.60 5.27 6.30 6.51 5.90 4.20 2.79 1.20 0.62
Average Precipitation in Cincinnati 40.9Average Evapotranspiration in Cincinnati 40.3
What is Effective Rainfall ver. Actual Rainfall?
Catch It!
How do we catch it?
Don’t Let It Get Away!
• Sources of Rain Water? “I wasn’t thinking the sky!”
– Roofs • Least amount of pollutants• Elevation of gutter allows directing to tank without pump• Easy to pre-filter and provide first flush• Low cost of conversion
– Pavement• Dirt and pollutants are more abundant• May need pumps to move water to storage area• Can be expensive to convert for collecting Rain, more cost
effective if done during construction
Don’t Let It Get Away!
• Sources of Rain Water?– Landscape Areas • Detain or Retain?• Contour planting• Rain Gardens• Soil improvements
Site Comparison
Area Home 1” Rain Bank 1” Rain
Land SF 22700 45500
Pavement SF 900 24200
Roof SF 1200 748 gal 5800 3613 gal
Landscape/turf SF 20600 91% 15500 34%
Rainwater Formula ( SF x .623 = Gal. Collected for 1 inch rainfall).623 is a constant that coverts Square Feet to Gallons
How to figure the Sq. Ft. of a roof
Home PWR / AWPlant Water Requirement / Available Water
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
Water needed for plantsRainTotal Available
Home Property
Bank PWR / AWPlant Water Requirement / Available Water
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
Water needed for plantsRainTotal Available
Bank Property
What are we going to water
• What are we going to use the water for• When will we need it.• Where will it be located
How much water do our plants need?
• Practical methods , the kind you use every day
• Management methods, depends on how much management budgets for watering
• Scientific Methods, good for developing a base line to use along with your practical methods
Plant Water Requirement (PWR)
• PWR = Landscape Coefficient X Reference ET
KL = KP x Kd x Kmc
• KL = landscape coefficient
• KP = plant factor
• Kd = vegetation density factor
• Kmc = microclimate factor
Plant Factor
Plant type Maximum appearance
Acceptable appearance
Low maintenance
Trees 0.90-0.95 0.70-0.75 0.45-0.50
Shrubs 0.60-0.65 0.45-0.50 0.30-0.35
Desert plants 0.40-0.45 0.30-0.35 0.20-0.25
Ground covers 0.70-0.80 0.50-0.60 0.30-0.40
Mixed planting 0.90-1.00 0.75-0.80 0.50-0.55
Kd = vegetation density factorKd refers to the collective leaf area of the plants covering or shading an area of groundMore foliage equals more transpiration hence more water is needed.
Kmc = microclimate factor
Plants growing is shade need less water
Plants growing next to a brick wall on the south side of a building need more water
Calculating PWR
6.5”/month * .7 = 4.6
1200 SF of plantings(1200 x 4.6) = 460CF of water
12 460 x 7.48 = 3440 Gal for month
7.48 gal per CU FT of water
Large Underground Tank
Rain Water Storage
Rain Water Storage
Rain Water Storage
Storage Tank Cost
MATERIAL COST, Small System COST, Large system
galvanized steel $225 for 200 gallons $950 for 2000 gallons
polyethylene $160 for 165 gallons $1100 for 1800 gallons
fiberglass $660 for 350 gallons $10,000 for 10,000 gallons
ferro-cement Price variable upon location
Price variable upon location
fiberglass/steel composite $300 for 300 gallons $10,000 for 5000 gallons
aluminum Cost prohibitive for water use
Cost prohibitive for water use
http://www.lid-stormwater.net/raincist_cost.htm
Using the Rain Water
• Most Rainwater Harvesting System are best utilized watering landscape plantings not turf because of the limited size of storage units
• If you have a large storage area such as a lake all planted areas can be watered with the stored rainwater
• Most systems will need some sort of pump to distribute the water through a pipe net work
Amount of water needed per 100 Sq. Ft. per month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Gal/100SF
27 49 95 157 230 275 284 257 183 122 52 27
Types of irrigation for landscape Beds• Hand Watering• Pros:– Can apply varying
amounts of water to specific plant
– Can conserve water resources
– Allows for visual inspection of plants
– Equipment cost are low
Types of irrigation for landscape Beds
• Hand Watering• Cons:– Labor cost are
very high– Need skilled
labor– Time consuming
Types of irrigation for landscape Beds
• Automatic overhead irrigation
• Pros:– Well designed systems
eliminate waist– Very low labor needs– Large water window
(application time)– Frees up labor for other task
Types of irrigation for landscape Beds
• Automatic overhead irrigation• Cons:– High initial expense– Mostly a shotgun approach– Blocked easily by plant
material– Inflexible to alterations– Wets foliage
Types of irrigation for landscape Beds
Drip and low volume irrigationPros:
Highest potential efficient use of water Low labor needs Economical to install Largest water window Places water at or near the roots Keeps foliage dry Low precipitation rates
Types of irrigation for landscape Beds
• Drip and low volume irrigation
• Cons:– Can be unsightly– Easily damaged when working
in the beds– Hard to visually inspect its
operation– Needs clean water
Best types of irrigation for landscape Beds
Most cost effective in the long term, utilizes the ever more precious resource of water better than any method, will get you LEED points , very flexible to change, can be unsightly if not installed properly.
Drip and low volume irrigation
Best types of irrigation for landscape Beds
• Controlling the rate of application– Drip and low volume irrigation have very low
precipitation rates. Hand watering can be controlled to eliminate run off as well.• No run off• Will not remove air from soil unless it is allowed to run
for to long of an irrigation cycle
– Over head irrigation generally has a very high precipitation rate , so do hose end sprinklers
Best types of irrigation for landscape Beds
• Low volume irrigation provides the most advantages over the alternative methods– Efficient use of water– LEED qualified (GREEN)– Waters better than most rain storms as considered
against uniformity and precipitation rate– Drip goes hand in hand with rain water harvesting
Best types of irrigation for landscape Beds
• Rain water harvesting– If you are using any type of cisterns to capture rain
water, drip is an Ideal way to use that water• Need to filter the water before use• If water is from pavements check for soluble salts and
other contaminants
Down Load This Presentation
• ftp.appliedwatertechnologies.com
• Name: [email protected]
• Password: tri_stateGIE