Hydrology and Rainwater Harvesting
Hydrology – The Study of Water
Water is one of our most important natural resources. Without it, there would be no life on earth. Scientists look for water on distant planets as the prime indicator of thepossibility of life on that planet. As with all nature resources, the supply of wateravailable for our use on is limited. Although there is plenty of water on earth, it is notalways in the right place, at the right time, and of the right quality. Adding to the problemis the past and current improper discharge of toxic chemicals into our water supplies.Hydrology has evolved as a science in response to the need to understand the complexwater systems of the Earth and help solve water problems.Water and PeopleMuch of our water use is hidden. Think about what you had for lunch. A hamburger, forexample, requires water to raise wheat for the bun, to grow hay and corn to feed thecattle, and to process the bread and beef. Together with french fries and a soft drink, thisall-American meal uses about 1,500 gallons of water–enough to fill a small swimmingpool. How about your clothes? To grow cotton for a pair of jeans takes about 400 gallons.A shirt requires about 400 gallons. How do you get to school or to the store? To producethe amount of finished steel in a car has in the past required about 32,000 gallons ofwater. Similarly, the steel in a 30-pound bicycle required 480 gallons. This shows thatindustry must continue to strive to reduce water use through manufacturing processes thatuse less water, and through recycling of water.Hydology ConceptsThe central theme of hydrology is that water moves throughout the Earth throughdifferent pathways and at different rates. The most vivid image of this is in theevaporation of water from the ocean, which forms clouds. These clouds drift over theland and produce rain. The rainwater flows into lakes, rivers, or aquifers. The water inlakes, rivers, and aquifers then either evaporates back to the atmosphere or eventuallyflows back to the ocean, completing a cycle.This Water Cycle, also known as the Hydrologic Cycle or H2O cycle, describes thecontinuous movement of water on, above ,and below the surface of theEarth. Water canchange fromliquid, tovapor, and toiceat various places in the water cycle. Although thebalance of water on Earth remains fairly constant over time, individual water moleculescan come and go..
Rainwater Harvesting Can Help
Summer weather is more sporadic, with unpredictable rainfall and hot dry spells. Rainwater harvesting systems provide a way to provide much, or even all, of your outdoor watering needs during this time. Most summer rain storms deliver a ¼ inch of rain, but many times we get over 1 inch deluges. Because the typical residential roof can collect a significant amount of rainfall, the amount of water saved depends on the capacity of your rainwater collection device(s). If you want to store water for irrigation between summer storms, you will need a rainwater collection device of sufficient size. Connecting 2 or 3 collection devices together or installing collection devices at more than
one downspout is an easy way to multiply your storage capacity. To help plan your rainwater harvesting set-up, consider the following:
1 inch of rain on 1 square foot of roof yields 0.6 gallons.
1 inch of rain onto a 10 ft x 10 ft. area (100 sq. ft) yields 60 gallons.
1/4 inch of rain onto a 1,000 area yields 150 gallons.
Multiply the square footage of your roof that drains into each individual downspout by 0.6 gallons to get your roof runoff volume. Either use a single collection device and prepare for occasional overflows, or select a collection device that can link to another to collect as much rain as possible. Example: One side of a one-car garage is draining into the barrel. If that roof area is 15 ft x 20 ft (300 sq. ft.), then 1 inch of rain will yield 180 gallons of roof runoff into the collection device. A more common storm event only delivers ¼ inch of rain, producing 45 gallons that will flow into the collection device.
Water your garden naturally with untreated, air-temperature, non-chlorinated water.
Stop storm water from polluting neighboring waters by keeping it where it falls.
Collect and direct rain water away from the foundation of your house and to your garden.
Why Rain Barrels?
• Up to 40% of summer water use is for irrigation. Reduce your household water needs by collecting rain water
• Provide water to areas that can’t be reached by your hose.
• Store rainwater for an un-rainy day.
• Collect and direct rain water away from the foundation of your home and to your garden.
• Stop storm-water from polluting neighboring waters by keeping it where it falls.