Date post: | 15-Jan-2017 |
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Environment |
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LOW TECHNOLOGY INNOVATIONS TO REDUCE WATER EVAPORATION, VECTOR AND ALGAE GROWTH IN OPEN WATER HARVEST SYSTEMSBy : Jervis E Rowe( Abbey Garden Farm, Central Greenhouse Supplies & Services)
BAUXITE PIT TURN POND
OBSERVATIONS
Rainfall is declining
Evaporation rates are increasing
Climate is warming up
THE GENERAL PICTURE
Quantity of water reaching reservoirs, rivers and streams is decreasing
Evaporation losses from the above sources is increasing
Irrigated plants are demanding more water as temperature rises
REALITY OF THE SITUATION
To purchase and transport water for Agriculture is too expensive
To implement measures to reduce evaporation will increase your cost of production
To do Agriculture with out water is impossible
UNDERSTANDING WATER EVAPORATION
Evaporation of water occurs when the exposed surface looses molecules to the atmosphere in the for of water vapor
Water vapor rises to form clouds
FACTORS AFFECTING THE RATE OF EVAPORATION
Humidity
Speed of air passing over the water
Temperature , ( 1degree C reduction in temp. can mean 2,900 gallons water saved /acre/day.)
FACTORS AFFECTING RATE OF EVAPORATION
SOME PRE-REQUISITES TO REDUCING EVAPORATION
Keep water cool
Keep water depth above 3 ft
Cover water
ECONOMICAL WAYS TO REDUCE EVAPORATION
Floating covers
WER ( Water Evaporation Retardants)
Aquatic Plants
Trees, shrubs and bushes
Trellising system with a vine crop
Less disturbance to water surface
FLOATING COVERS
Acts as a barrier between water surface and the air
Reduces speed of air passing over the water
Reduces contamination of water, falling debris , algae and other water plants
Reduces break down of pond liners
FLOATING COVER
WER ( Water Evaporation Retardants)
Creates a film over the water surface
Example : Acilol TA 618 , emulsion made from a fatty alcohol
AQUATIC PLANTS
Shades the water below
Absorbs some of the solar radiation
Examples: water lilies, floating hearts
Far less expensive when compared to floating covers
WATER LILIES
TREES, SHRUBS AND BUSHES Planted outside and around the pond
Use plants that do not shed a lot of leaves or pods eg. Evergreens
TRELLIS WITH VINE CROP
Provides shade and wind break
Example: beans, passion fruit
REDUCE AGGITATION
Reduce splashing at water surface
Allow inlet pipes to touch water
Avoid the use or water wheels where possible
WHAT IS ALGAE ?
Chlorophyll containing plant existing very low on the evolutionary chain
3 main groups , filamentous , branched , planktonic
May occur single, colonies or mat
Reproduces asexually AND asexually
COMMON STRING AND GREEN ALGAE
FACTORS AFFECTING ALGAE GROWTH
Pond size and depth
Water stagnation
High nutrients and light
POND SIZE AND DEPTH
Small & shallow=high light & temp=algae
Stagnant water, limited wave action promotes growth
High P & N is food for Algae
ALGAE IN IRRIGATION WATER
Creates blockages ( pumps, filters, emitters, meters, wheels and gates
Reduces water quality( reduces oxygen, causes contamination)
When algae die they sink to the bottom of the pond and contributes to the build up of sludge
ALGAE MANAGEMENT IN SURFACE PONDS
Physical/ Mechanical control
Chemical Control
Biological Control
PHYSICAL / MECHANICAL CONTROL
Rake out mat form algae
Result is immediate
No chemical cost or risk
Algae removed can be used as mulch
CHEMICAL CONTROL( Hydrogen peroxide)
Organic
Oxidizing agent
Breaks down to water and oxygen( relatively expensive)
CHEMICAL CONTROL ( copper) In use for several years
Used as recommended has no adverse effects
CHEMICAL CONTROL ( Dyes) Blocks part of the light spectrum that
algae need to photosynthesize
Example : Aquashade ( product name)
BIOLOGICAL CONTROL OF ALGAE Use of organism that feed on or rob
algae of their food or oxygen
Triploid grass carp eat algae when other food is limited
PATHOGENIC MICRO ORGANISMS IN POND WATER
These may include but not limited to :
Bacteria eg. Salmonella E Coli
Protozoa eg. Crytosporidium , Giardia
Viruses eg. Noroviruses
CONDITIONS FAVORING BACTERIAL GROWTH IN POND WATER
Ph 4.5-6.5
Temperature above 45degrees F
0.2- 1.0 ppm iron in water
0.1 or more ppm of Hydrogen Sulfide in water
Bacteria produces slime which affects water quality
MANAGEMENT OF BACTERIA IN POND WATER
Best done locally with chlorine
Ultra violet ray flow cells ( expensive)
Osmosis (expensive)
Water Chlorination
Chlorine disrupts cell membrane
Cell looses contents
Cell looses function
Micro-organism dies
UV light treatment
Light penetrates cell Disrupts DNA , prevents reproduction Kills up to 99.99% bacteria and
viruses Does not alter water ( taste and
odor) Does not add chemical Use very little energy Low maintenance ( change bulb
annually)
Ozone water treatment Oxygen is electrically charged to produce
ozone ( O2--- O3) Ozone is very unstable and will react with
material in an oxidizing reaction
Ozone is one of the strongest sterilizing agents
Apply ozone using a venturi or centrifugal pump
After oxidation of ozone oxygen is left in solution
LOOKING AHEAD Rain water which sometime gets to the
Island from other region must be harvested and effectively stored
Water already here must be screened for quality, corrected accordingly and properly stored
Surface water from roads, parking lots or other paved areas can be harvested and treated for certain agricultural uses
Irrigation techniques must be efficient and reflect best practices
THANK YOU