-Water-Harvest the Rain?

SLOW THE FLOW – storm water management film explaining how to make your landscape act like a sponge by
Eco Landscape California


We are expecting rain on November 12.

On October 5, 2011 we received our first rainwater for the 2011-2012 school year – – – 1 inch, just enough to water in the weed seeds.  Any way to use that water productively on the SYH site?  A 1,000 square foot roof area can produce more than 600 gallons of runoff for every 1″ of rain.

Area of gymnasium roof that drains on SYH site is 96' long and 32' wide=3072 sq feet

Based on measurements above, that means we could possibly collect 1800 gallons of water in just a 1″ rain event. That would be enough water to provide 200 plants water for 2.25 months. Average annual rain for Ojai is about 21″. Once the native plants have been planted, it has been suggested that we provide water for approximately 6 months, with watering done by hand the first 2 months to see how much water is needed, and then switch over to drip irrigation.

Looking into water conservation options, how much rain water is available from the gym roof that drains down the 3 rain gutters that empty out into the Schoolyard Habitat site?

Benefits of capturing rain water:

-reduce storm water runoff

-provide un-chlorinated, soft water for plants

-water is available from storms,  no energy costs required

-could use during drought as back-up or for fire suppression as back-up

We will eventually need to determine what our water needs are based on what is planted and when.  But first lets see how much water is available to us.  Even if we just capture the “first flush” a few times:

Calculations:

Roof Area (square feet) * rainstorm (inches) * .62 (conversion) = Water storage needed (gallons)

3072   *   1″   *  .62 = 1,905 gallons of water /50 gallon containers = 38-50 gallon containers containers or 7- 250 gallon containers

More information on how to install 55 gallon rain barrels:
http://www.emmitsburg.net/gardens/articles/adams/audrey/water_barrel.htm

A solid design using mulch and natives will help reduce  water needs for new plants, which we expect will take 6 months to get established.  But what are some site specific techniques we might use to harvest the rain?

Nate made some great recommendations during his visit to our site on October 19, 2011:

  1. When planting natives, create a berm with dirt from hole, placed on down hill side in a crescent shape  to create water retention basin, planting other plants below and above.
  2. To “slow it- spread it- and sink it”and avoid puddeling at low spot in pathway, create 2-3 branching patterns on both sides of walkway that lead out into planting area.
  3. To retain rain water in low spots, create “straw  book swales” planted into the slope to create a terraced effect at the base of the slope.
  4. Plant a sycamore tree  near south side of central planter to provide water retention basin for the tree.
  5. Create a bridge over pathway to allow water to collect in natural retention areas from 3 rain gutters  that drain into the SYH (see where the weeds are currently growing).
  6. Create weaving  zig-zag pattern in dry creek bed to collect water.
  7. Provide a wind break area with low, medium, high, then medium high plants to provide a natural wind barrier when wind gradually rolls off site.
  8. Purchase “water hog” barrels that collect water directly from rain gutter drains (when funds become available).

See these ideas represented in plan below (to be provided later).

**UPDATE** February 26, 2012
We just had 2 weekends of rain, glorious rain!
Total rainfall in Ojai – APCD RAWS – October – September

24 Hour Amount at 8:00am on February 26: 1.13″

Rain Total Last 5 Days: 1.49″

Accumulated Total to Date: 8.60″

Normal to Date: 18.36″

Percent of Normal to Date: 46.8%

Last Year Rain to Date: 27.88″

So far in 2012, we’ve had 1.19″ in January, 0.11″ in February and 3.22″ in March. February was one of our driest months in the last 5 years, and March one of our wettest months in the last 5 years. This is from the Ojai Valley Weather page in the Ojai Valley News http://www.ojaivalleynews.com/pages/weatherpage.html provided by Ventura County Watershed Protection District.

They say one of the things to look for with climate change is changes in the extremes of the weather. For instance, hot summer weather gets hotter, cool winter weather gets cooler (like snow on the mountains in March), rainy months get wetter/drier.
The YouTube link below is from CA Dept of Water Resources on climate change, and discusses forcasts of future precipitation in CA.

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