Preparing for drought conditions with a catchment system

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Preparing for drought conditions with a catchment
system

• Joe Brown, PhD
• University of Alabama
• New College
• joebrown_at_bama.ua.edu
• Southern Sustainable Agriculture Working Group
• January 16-19 2008 Louisville, KY

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Handouts and presentation

• Available at website
• bama.ua.edu/brown/water.html

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Rainfall there aint any

• Increasing climatic variability
• More frequent and severe droughts in SE region
• My two states in particular
• Whats going on?
• Hard to say, but for now the outlook isnt great
• Lets take a brief look

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Lucky Kentucky
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El Niño 2006-2007 (hot, dry summer in SE) La
Niña current conditions (mild, dry winter)
A double whammy
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?
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Okay, so now what?

• We must start thinking of water as a scarce
  resource mindset shift
• Lets look for ways to cut back on water by
• Using catchment systems
• Start thinking more about water storage
• Managing your pond creating a pond if you dont
  have one
• Implementing a water conservation plan on the
  farm
• Considering water in all decisions
• Wells do go dry, water costs will go up
• Good news in the SE, we still get plenty of rain
  even in our driest years!
• And occasionally, we get lots in spite of it all
  (2003 comes to mind)

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Rainwater catchment

• But, I thought we were talking about not having
  any rain?
• Well, we still have rain, but it comes in less
  frequent bursts more variability
• Still plenty more than out West
• Capturing it is the key
• Basic rainwater catchment roof improvements,
  conveyance and quality control, storage, and
  treatment

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Rainwaters been around for a long time
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In MANY forms
Proutworld.org
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Including this one

• BASIC ELEMENTS
• Collection from a roof
• Conveyance
• Storage
• And now, a bit about each

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Roof materials

• When choosing a roofing material - the smoother
  the better. The quantity of rainwater that can be
  collected is also a function of roof texture
• Can also impact quality
• Water quality from different roof catchments is a
  function of the type of roof material, climate
  conditions, and surrounding environment
• More on this in a moment
• NOTE! Collection surfaces can be non-roofs
  packed earth and concrete are common in some
  countries

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Roofs should be free of nastiness more on that
when we get to quality
May need to trim overhanging trees as debris can
get out of hand
SLOPE IS IMPORTANT TOO
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Capture efficiencies depends on roof material

• For a tile/metal/concrete/asphalt roof assume a
  95 runoff efficiency
• Gravel 70
• Bare soil 70
• Grass 17
• Source harvesth2o

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A word about rainwater quality and roof materials

• Copper roofs and heavy metals
• Asphalt shingles, especially new ones, and
  especially on hot days leeching of organic
  nasties into water
• Some shingles have imbedded chemicals / moss
  inhibitors that can be nasty
• No roofing material has been approved or
  certified for potable use
• By the NSF or EPA or any other government or
  regulatory organization
• As for as metal, galvanized metal, painted or
  unpainted with a nontoxic paint, are common.
  Other roofing type materials include terra cotta,
  tile, slate, and fiberglass
• Roofing materials should have as little toxic
  material on it as possible, to reduce leaching
• Water collected from cedar roofs may be too
  acidic
• Beware lead flashing

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Gutters and downspouts
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Gutters

• Aluminum gutters
• Galvanized steel gutters
• PVC is used widely
• Bamboo can be a good choice for you DIYers if a
  bit difficult to work with for the uninitiated
• Rain chains
• Ensure constant slope
• Think of a gutter as a river - not a swamp
• Gutter guards
• Clean and inert the name of the game

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Clean out your gutters! This stuff will end up
in your rainwater tank Debris makes your system
inefficient
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Downspouts

• Anything from chains to traditional aluminum
  downspouts can be used to get the water down from
  the gutters
• Sealed PVC piping is often used close to the
  ground, and where the water needs to be
  transported horizontally
• This piping must be sized for good flows, storm
  events, and easy cleaning
• 3-4 diameter, with screens to keep out leaves
  and animals appropriate for 1000SF catchment
  area

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Debris traps

• A series of debris traps and filters can protect
  water quality

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Rain chains
For those of you with style Popular choice Can
also use ropes of various kinds Not very
efficient
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A few more words about quality protection on the
collection side

• In addition to worrying about the roof material
  and debris traps, consider
• First flush systems
• Barrels in series
• You want to prevent things from washing off roof
  and ending up in your nice, clean rainwater
• That you might even think about drinking

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First flush (AKA foul flush)

• A diverter of the first water that comes in a
  given rain event
• Usually sized to divert the first 1 or so by
  volume of a 1 rain event
• Sizing depends on roof size, material, etc there
  are formulas and rules of thumb, but all are
  fairly arbitrary
• About 10 gallons per 1000 SF is what Ive used
• Designed to fill with contaminated water from a
  rain event and empty itself over a 24 hour period
  so that it is ready for the next time it rains
• This system is used in most parts of the world to
  improve water quality for potable rainwater
  systems
• Removes 80 or more of the pollutants that
  collect on the roof or in the gutters and become
  dissolved or suspended in the water

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More on first flush
from gutter

• Commercially available units ()
• Small tank with diversion
• Many designs are used

To storage
Floating ball
20 Gal
Large diameter PVC pipe with small hole drilled
in bottom
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The barrels-in-series treatment system

• Series of tanks that allow for settling out of
  contaminants

H2O
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And now, a bit about storage options
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Water storage

• The key to making rainwater available when and
  where you need it
• Storage tanks/cisterns take many forms and vary
  greatly by cost, volume, and materials
• The most common storage tanks in the US are the
  above ground molded polyethylene tanks (300 -
  5,000 gallons)
• 1,000 3,000 gallons is the correct range for
  our region that will allow for ample domestic or
  some garden use
• Ferrocement tanks are widely used elsewhere as
  well as historically in the US

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Tank options

• Fiberglass
• Polyethylene
• In-ground polyethylene
• Metal
• Concrete/block
• Ferrocement
• Stone/masonry
• Earthship-style rammed earth tires/plaster
• Wood tanks, swimming pools, other materials, etc

• Harvesth2o.com

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Fiberglass tanks

• Light-weight, reasonably priced, and long lasting
• Small barrels to 15,000 gallon tanks, several
  shapes
• Smaller fiberglass tanks (i.e. under 1,000
  gallons) are expensive for their size, so
  polyethylene might be preferred
• Tanks for potable use need to have a
  USDA-approved food-grade resin lining and the
  tank should be opaque to inhibit algae growth
• Generally recommended for any tanks used for
  potable water
• Durable and easy to maintain

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Fiberglass
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Polyethylene

• Most readily available, cheapest of all the
  commercial options
• Many shapes, sizes, versatility
• Most common in the USA
• Have been known to be leaky
• Opaque plastic colors may need to be shaded or
  buried
• Dont retain paint well
• May need reinforcement if buried
• Barrels to 10,000 gallons

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Polyethylene
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Clemson University system
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Metal tanks

• Relatively expensive option
• Most tanks are corrugated galvanized steel dipped
  in hot zinc to improve corrosion resistance
• For above-ground use (risk of corrosion and LUST)
• Old or recycled tanks may contain nasties (e.g.,
  lead and perhaps should be avoided
• Unless you have the resources to test water
• Low pH of rainwater can leach out metals that are
  more soluble at low pHs
• Brass and bronze fittings should not be connected
  directly to the tank as they will cause corrosion

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Metal
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Metal with algae cover
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Concrete

• Versatile, poured in place or prefabricated
• Concrete blocks, cinder blocks, other blocks
• Constructed above or below ground
• Owner or contractor-built
• Concrete will over time decrease the
  corrosiveness of rainwater by leaching into the
  water
• Also taste advantages (Ca, Mg)
• May require high quality coating inside for
  potable use
• Underground concrete tanks are prone to cracking
  and leaking, especially when in clayey soil
• Leaks can be easily repaired, although the tank
  may need to be drained to make the repair.
• May need expertise of a structural engineer to
  determine the size and spacing of reinforcing
  steel
• Xypex(TM) can be used to seal leaks in potable
  tanks

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Concrete
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Concrete
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Cast concrete or pottery
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Ferrocement

• Steel and mortar composite material
• These tanks can be above or below ground and can
  be done by contractors or homeowners
• Developed in third-world countries to be
  relatively low-cost and durable
• Typically chicken wire-wrapped around a light
  framework of rebar, embedded in the concrete.
  Walls can be as thin as 1" and still be strong
• It can cost less to build than a concrete-only
  tank
• Will need maintenance and repair as cracks
  appear
• Paint it white to reflect the sun's rays, reduce
  evaporation, and keep the water cool

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Strength is in the rebar/wire mesh
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9000 gallons 400 kids for one year 3 months, no
rain!
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Plastered tire/rammed earth/Earthship tanks

• A circle of buried tires with a wire mesh inside
  covered with plaster
• Will need periodic maintenance to repair cracks
  on the inside
• Labor intensive
• Meant to be buried and can be very economical for
  large tank sizes (i.e., 10,000 gallons/37,900
  liters), especially if owner-built
• Use great care in the plaster work
• Can last forever

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My new crazy idea
TAKE ADVANTAGE OF OUR TRADE DEFICIT WITH CHINA
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Another crazy idea

• Store water in existing wells
• Some researchers in India are testing it out.
• (link on the website)

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 --  Low/No                     High/Yes
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Some things all tanks need

• A solid secure cover
• A coarse inlet filter
• An overflow pipe
• A manhole, sump, and drain to facilitate cleaning
• An extraction system that does not contaminate
  the water e.g., a tap or pump
• A system to prevent spilled water from forming
  puddles near the tank
• Additional features might include
• System for reusing water from foul-flush

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Other considerations with tanks

• Water temperature can be elevated if using a
  dark-colored tank
• Tanks are often dark in color to discourage algae
  growth
• Try watering your tomatoes with 120F water and
  report back to us next year
• All of them will need to be cleaned out
  periodically, so plan for that
• All need to have a sloped bottom away from the
  outlet so that settled solids dont gunk up the
  outlet

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Sloped bottom to the tank away from outlet
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Protecting quality in rainwater systems

• First flush / foul flush systems
• Debris traps
• Roof maintenance
• Roof materials
• Tank materials
• Post-storage treatment

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More on rainwater quality (post-storage)

• Not very much data on this
• In most of the world, rainwater is usually of
  much greater quality than other sources, and its
  free! (with the cost of the roof improvements,
  gutters, and tanks)
• Atmospheric pollutants do find their way into
  rainwater, usually at very low concentrations
• Acid rain, VOCs, particulates
• There have been documented exceptions
• Urban areas can have issues with this
• Be aware of the considerations, but usually
  quality is not a huge concern (BUT DEPENDS ON
  USE)
• Especially for non-potable uses

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There may be municipal restrictions on rainwater
use and quality controls
Check out tying into your domestic system,
reusing water
GREY WATER!
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Potable use

• Treatment for potable use (usually not
  recommended, occasionally not legal)
• Chlorine
• Requires proper dosing to 3-5mg/l difficult in
  practice to get this right
• Ultraviolet requires electricity and may not be
  practical
• http//www.harvesth2o.com/uv.shtml
• Filters
• RO/micro/ultra/nano filtration (POE devices)
• Sand or other granular media filters (less
  effective)
• Safe storage combined with no treatment (most
  common in developing countries)
• One drop, silver-based technologies, silane
  coatings
• Brita wont cut it
• Human pathogens dont generally grow in rainwater
• Can persist, however, if foul-flush system is
  inadequate

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Two examples of small rainwater systems
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Design for a chicken houseexample project for
Carrboro

• 6 x 8 corrugated metal
• Attached to one side of roof thats 5 on a 512
  pitch
• Catchment area is 6 x 12 on 512 pitch
• Works out to 66 square feet (footprint)
• Always calculate catchment area as on-ground
  projection of a sloped roof
• Gutters connected to 1 55 gallon drum
• Connected by hose to watering can

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Catchment area a x b(birds eye view of roof
outline)
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My chicken house
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12
55g
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Looking up rainfall data
CONSERVATIVE ESTIMATE 3 per month or 36 per
year Spreadsheet available at http//bama.ua.edu/
brown
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ASSUME 12 hens drink 1 gallon of water per day
(drinking and panting to cool off) Assume you get
half of normal rainfall, and 20 is wasted USE 1
55-gallon drum. Conversion factor 1 CuFt 7.48
gallons
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The finer points of design

• Cleaning off the roof, trimming back oerhanging
  trees
• Using scrap metal from my own personal dump left
  behind by the barbarian rednecks who were on our
  place before
• Working with the random fittings and hoses I
  already have lying around
• Considering buying a new drum
• Total materials cost approximately 0

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Design for a household system in McCalla, Alabama

• House footprint 1250 SF
• Daily use of 100 gallons for all domestic uses
  and our attached small greenhouse
• Probably an overestimate since were
  conservation-minded
• Supplemental treatment via POU/POE filtration
• First flush system

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Demand take a close look

• How much water do you anticipate using?
• 50 gal per day? 200?
• 95 is average for Americans!
• The WHO says we can live on less than 2 per day
  for essential drinking and cooking

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Find your citys data in .xls format
http//bama.ua.edu/brown/water.html SOURCE
http//www.harvesth2o.com/US_rainfall.shtml
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Use 30 year data with 10 loss factor
at end of the month
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Meeting supply and demand
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Other points

• Using 2000 gallon water tank
• Metal but in good condition, also salvaged
• Existing gutters
• Aged asphalt shingle roof
• Oerhanging trees
• First flush system of PVC floating ball type
• Post-storage sand filter and UV disinfection (or
  ceramic filters) for potable use
• Parallel line for greywater
• Id better start becoming adept at plumbing.
• Every project an opportunity to learn things
• Not to mention purchase fun tools

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Designing YOUR system

• Identify needs and goals
• Figure out what catchment area youre working
  with
• Get your rainfall data the more local, the
  better
• Why not get a weather station? Just remember to
  empty the rain gauge!
• Calculate supply using a simple spreadsheet
• Full example in a moment
• Assess demand
• Account for all the conserving youre going to
  start doing ?
• Try to live within your hydrologic (and ecologic)
  means!
• Ponder tank sizes tradeoffs between storage and
  cost
• Include ample assumptions for losses, especially
  at first
• Can always put in overflow barrels that are
  extra
• Include allowances for drought, increased
  proportion of rainfall occurring in less frequent
  but more intense bursts
• Leads to more losses due to splashing,
  overwashing gutters
• Like with any new thing, best to start small
  (in size and )

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Sizing the storage tank

• Where supply meets demand
• Major determinant of cost
• For domestic/small garden uses 1000 3000
  gallons
• More storage provides for greater drought
  protection
• Tradeoff!

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Rainwater for irrigation

• Capture is critical usually theres the least
  rain when temperatures are highest and irrigation
  is most important
• Need to boost storage for irrigation use
• You will be able to find uses for your stored
  rainwater, so investment in tanks is always good
• Not very practical for large scale row crop
  operation, but
• Water where you need it without pipes if you have
  a greenhouse, barn, chicken house, etc far away
  from current water sources
• And can be gravity fed no pumps or less pumping
• Can supplement other sources
• Widely used for this purpose in some places of
  the developing world

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Stored rainwater versus paying for tap water

• 250 gallons 1
• Often more in smaller, private systems
• In our region, a 1000 system will pay for itself
  in 3 10 years if only the bottom line is
  considered
• 3000 gallon capacity tank(s) and few extras for
  the roof and gutters
• Depends on use, rainfall, cost of tap water, how
  efficient the system is, etc
• Could make a lot of sense from a great many
  perspectives, not just economic
• Increasing your self sufficiency in times of
  drought

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Rainwater versus wells

• Wells can and do run dry, so good to have a
  backup plan
• North Carolina groundwater map
• Not always available
• For example, some areas of Alabama
• buyameter.org

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By the way marketing opportunities

• Touting drought resistant or low-water crops
• Highlighting sustainable water use on the farm
• Rainwater harvesting as a selling point
• Focus on farm impacts on water
• Well-managed agricultural land provides for
  infiltration
• Erosion controls and BMPs for reduction of runoff
  and therefore waterborne pollution
• Grass swales, ponds, rain gardens
• Watershed, riparian zone, or wetland protection
• Make sure your customers know you are doing
  something good, maybe theyll buy another tomato

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Your own Walden Ponda water savings account
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First of all resources!

• Key ones are available on the website
• http//bama.ua.edu/brown/water.html
• Building a pond requires expert site-specific
  help
• Its both a science and an art
• Just a few general points here

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Selecting a pond site

• Put it over yunder has not been a successful
  philosophical viewpoint or modus operandi
• Several factors to consider, including
• Safety
• Soils
• Geology
• Topography
• Irrigation access proximity to crops

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A few different pond types

• Embankment (less expensive)
• Excavated (more expensive)
• Levee
• Watershed-levee
• Have a look at resources on the website

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Maintain your pond

• If you have an old pond site on your property,
  its well worth taking the trouble to clean it up,
  rather than negotiating permits and incurring the
  expense for a new one
• This is a resource to be maintained
• Can be expensive to dredge and repair ponds
• Vegetation decays, sediment accumulates and the
  basin erodes. Eventually, without help, the pond
  disappears
• Shallow water contributes to excessive aquatic
  weed problems and potentially to fish kills from
  low dissolved oxygen when average depth is less
  than 3 feet maintain adequate depth

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More on maintenance

• Beware of runoff or be prepared to recover your
  topsoil with a backhoe in 20 years and pay for
  the privilege
• Keep your pond surrounded by large grassy areas
  to prevent soil from washing into the pond from
  nearby fields
• Dont leave exposed soil in your catchment basin
  if you can help it
• Keep contours in mind, of course, anytime you
  disturb the soil
• Also keep in mind that the ponds own water can
  cause soil erosion
• Like capitalism, every pond contains the seeds of
  its own destruction
• Wind-whipped waves can eat away at a ponds banks,
  dam and spillway
• Common solutions include breaking up waves with
  an obstacle such as a floating log boom
• Aquatic plants?
• Keep livestock out of your pond as much as
  possible, both to prevent erosion and to maintain
  water quality

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Is my pond leaking or evaporating?
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Leaky ponds

• Excessive seepage is a common pond problem in
  many areas
• Most severe seepage problems can be traced back
  to two fundamental causes a poor site and/or
  improper pond construction practices.
• A poor site may be one in which either the soils
  are too permeable to hold water and/or the
  underlying geology is not conducive to holding
  water.
• Risky geological structure includes underlying
  cavernous limestone prone to develop sinkholes or
  exposed rock areas in the pond bottom around
  which water might channel beneath the pond.
• Seepage rates can vary considerably for ponds,
  depending on the dominant soil type.
• Properly constructed ponds on good sites will
  have low seepage rates.

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Leaky ponds, continued

• Improper pond construction techniques are often
  the cause of excessive seepage
• Avail yourself of resources no doubt available
  from your cooperative extension AND expert advice
  from folks whove built ponds that are still
  around
• Most embankment ponds require a cutoff and core
  trench compacted with a good-quality clayey
  material along the centerline of the dam and
  extending down into impervious material.
• Failure to properly install the core trench can
  result in excessive seepage through the base of
  the dam.
• This problem can sometimes be corrected through
  draining the pond and installing a new core
  trench in front of the dam.
• Proper soil moisture is very important for
  obtaining optimum compaction during the
  construction phase. Ponds constructed with soil
  either too dry or too wet can result in excess
  seepage due to poor compaction.
• There are several methods and materials that can
  be used to seal leaking ponds, including
  compaction, clay blankets, bentonite, chemical
  dispersing agents, and pond liners
• Much easier in construction than later!!!!
• See resources on website there are some very
  good articles on this

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Water conservation on the small farm

• Irrigation reducing losses, avoiding over
  watering
• Managing crops to get the most out of your water

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Being stingy with your water by asking the tough
questions
Youre probably already going through this mental
process
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Irrigation

• North Carolina is located in a humid region
  where irrigation must be planned in conjunction
  with prevailing rainfall conditions. In humid
  regions such as ours, applying routine amounts of
  irrigation water at regular intervals will almost
  always result in overirrigation and the needless
  waste of water and energy
• Evans, Sneed, and Cassell (1996) NCCES

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Checking soil moisture

• The feel method
• Instruments
• Dont want to over water
• In addition to wasting water, can lead to shallow
  roots, other issues

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Irrigation scheduling

• Delivering the correct amount of water at the
  correct time
• Know your crops water sensitivity and needs at
  various stages of growth
• Focus on critical points
• Monitor soil moisture, even if its just through
  spot checking with the feel test
• Ample information out there on this check with
  your extension

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So what are some simple steps for saving water?
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If you can, scale back

• Reduce area planted no use trying to stretch too
  little water over too little land you run the
  risk of overstressing everything
• Reduce production of water intensive crops if you
  can
• Focus on giving adequate water to those most
  critical () crops and cut corners on the
  extras that may not be as marketable
• Hard choices are sometimes needed

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Crop selection

• Certain crops and varieties are less sensitive to
  water stress
• May not be as productive
• May not have as high a market demand
• Talk to your extension agent and other folks to
  get ideas

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For example drought resistance and cover crops

• Sudan sudex is best
• One sees sorghum and millet planted together in
  many dry places around the world
• Sudan grass is not a legume, no nitrogen fixation
• Hairy vetch is moderately drought resistant
• Cowpeas (iron and clay peas) moderately drought
  resistant
• Crimson clover is not drought resistant
• I dont recommend kudzu, although it is drought
  resistant!

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Develop strategies to make the most of rain when
it comes

• A good response to longer periods of dryness
  broken by more violent rainstorms is to make your
  soil drought-resistant
• What you want is a way for your valuable plants
  to survive a temporary water deficit, without
  having to use a lot of water
• So, make sure that the water from a deluge
  doesn't run off
• Make the water percolate down to plants' roots
• Bare plowed soil loses water quickly to
  evaporation
• Ground cover of any kind helps
• More on this

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Water and your soil

• Soil type and structure is a major determinant of
  how much water is held and whether your crops can
  access it
• E.g., clay holds a great deal of water, but that
  water may not be easily accessible to plants
• Soils that are too sandy may not hold water well
  at all
• You can promote water infiltration, retention,
  and accessibility by developing proper soil
  structure and fertility
• Organic matter, cover crops (promote infiltration
  and reduce evapotranspiration), etc
• Advantage of reduced tillage, no-till systems
  undisturbed soil holds water
• Also advantages for pond buffer areas
• Worms

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Weeds and trees

• Remember, they compete with your plants for water
• And competition can be fierce
• Mature trees in peak summer heat can use 250
  gallons a day
• Roots may go out horizontally as far as the
  height of the tree
• May not notice until drought conditions are
  present

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The obvious things

• You know youre doing something wrong when
• There are puddles of water hither and yon
• You see jets of water coming up between rows,
  from valves, at couplings, etc
• Tiny rivers appear out of nowhere
• Use drip irrigation and lots of mulch/row covers
  where possible
• Use sprinklers in the evening/morning if
  necessary and maximize droplet size
• Want to deliver water so that it doesnt
  evaporate immediately
• Also dont stress out your plants when they are
  suffering from lack of water by feeding or pruning

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Thanks for your attention, yall