Download - ARUN SIR PRESENTATION AT ANIMATION CENTRE
kzmKXw
S.ARUN KUMAR(ASISTANT DIRECTOR)
SOILThe top layer of earth’s surface that is
capable of sustaining life.Is a three dimensional natural body occurring
on the surface of earth that is the medium for plant growth and whose characteristics have resulted from the forces of climate and living organisms acting upon parent material as modified by relief over a period of time.
It is the deterioration of soil by the physical movement of soil particles away from the original site. Water, wind, moving ice, sea waves and the use of implements by human beings etc, are the agents of erosion.(Biotic & abiotic causes)
SOIL EROSION
INDECATORS
• Mounds of relic soils around plants and under pebbles.
IT RESULT IN THE LOSS OF FERTILE TOP SOIL THAT IS SUPPORTING CULTIVATION LOSS OF PLANT NUTRIENTS MAKING LAND UNSUITABLE FOR CULTIVATION BY THE FORMATION OF RAVINES AND GULLIES SOIL ENTERING THE WATER COURSE REDUCES WATER QUALITY,REDUCES THE EFFICIENCY OF DRAINAGE SYSTEMS AND STORAGE CAPACITY OF LAKES AND RESERVOIRS. SOIL IN WATER IS A POLLUTANT AND IN THAT WAY INHIBIT FISH SPAWNING AND ENTRY OF LIGHT INTO WATER THAT IS NECESSARY TO SUSTAIN LIFE IN WATER THE FERTILIZERS/CHEMICALS IN SOIL MAY AFFECT
QUALITY OF WATER FOR DRINKING. CAUSE DAMAGES TO ROADS,RAILS AND WATER TRANSPORT
LOSSES DUE TO EROSION
Others2.71 m ha
Degraded forests24.90 m ha
Water logged3.20 m ha
Salt affected6.32 m ha
Ravines2.68 m ha
Wind erosion10.46 m ha
Water erosion57.16 m ha
Status of land degradation in India (Total Area: 329 m ha)
Source: MOA, 1994
Rain drops falling on earth surface from a height dislodge the fine soil particles from the soil mass. This detached soil particles are carried away in suspension along with overland flow. The flowing water over the land surface also can dislodge large number of soil particles of varying size and ultimately get transported to streams.
Movement of particles
by various agents
(TRANSPORTATION)
PROCESS OF SOIL EROSION
Loosening & dislodging of Particles
DETACHMENT/EROSION
Deposition of the transported particles(SEDEMENTATION)
INDESRIMINATE CUTTING DOWN OF TREES
OVER GRAZING OF VEGETATIVE COVER
FOREST FIRES
REMOVAL OF PLANT NUTRIENTS AND ORGANIC MATTER BY INJUDICIOUS CROPPING PATTERN
CULTIVATION ALONG SLOPES
FAULTY METHODS OF IRRIGATION
GROWING CROPS THAT ACCELERATE EROSION
CAUSES OF SOIL EROSION
TYPES OF EROSION
NATURAL/GEOLOGIC ACCELERATEDErosion of soil in its
natural stateRate of erosion is low
and generally invisible.Soil forming process.There is equilibrium
between soil formation and soil loss.
It happens under biotic and abiotic pressure.
Rate of erosion is high and is visible
Soil degrading processThe equilibrium between
soil formation and soil loss is broken and loss is higher than formation
DIFFERENT FORMS OF WATER EROSION
Loss of soil due to water movement is called water erosion. Excess rainfall generating run off causes water erosion and is increased by the sloping lands.
Rain drop erosion/Splash erosionSheet erosionRill erosion
Gully erosionStream bank erosion
Sea coast/shore erosionLand slide/land slipRavine formation
Rain drop erosion/Splash erosion
• It is the first step in the water erosion process. Splashing/detachment of soil particles occurring by the impact of falling raindrops is called splash erosion. Soil granules are loosened and beaten into pieces. The falling drops at a speed of 9 m/sec can create force of 14 times its weight. By this action the soil becomes a flowing mud. It can splash soil particles to about 60 cm ht and 150 cm away.
• Except in slopping lands it cannot make impact because soil particles
only to very small distances.
SHEET EROSION • The removal of a more or less uniform thin layer or sheet of soil by running water from sloping land is called sheet erosion. The splashed soil seal the soil pores and prevent infiltration and also cause sheet erosion
SHEET EROSION
RILL EROSION
• It is an advanced form of sheet erosion which occurs due to concentration of flowing water. As a result of water washing down the slope small finger like rills begin to develop on land surface. If not cultivated these rills may increase in number size and shape.
RILL EROSION
Gully erosion
RAVINE FORMATION
RAVINE FORMATION
• Ravine is a parallel set of deep and narrow gullies with abrupt sides. They are formed from un attended rills. It is usually associated with river systems.
Causes of ravine formation
• Abrupt changes in elevation between river bed and adjoining land
• Deep and porous soil strata with high erodibility
• Poor vegetative cover• Backflow of water during recession period
STREAM BANK EROSION
• Scouring of soil material from stream
bed and cutting of stream bank by the
force of flowing water. Stream erosion
happens at lower end of water
channels where as gully erosion is
towards upper portion of channels.
SEA COAST/SHORE EROSION
• Tidal waves of the sea and rough and roaring waves dash on the coast every time swallowing bits of land. High velocity winds may intensify the hazards of this erosion
LAND SLIDE /LAND SLIP
• It is the downward and outward movement of soil forming material composed of natural rocks, artificial fills or combination of these materials.
• Land slip-Smaller mass moving all on a sudden.
• Land slide-bigger mass moving slowly moving through initiating as slips
Causes
• GEOLOGIC-weak geology, lack of vegetative cover
• HYDROLOGIC-Water seeping and over saturation
• SEISMIC-Earth quakes
Topography
Length of slope Degree of slope
Slope = Vertical /Horizontal
= tan x
Degree & length of slope
• Steep slope-Velocity increase, depression storage
• Slope increase four times velocity doubles and erosive power increase four times
• Quantity 32 times size -64 times• Length of slope increase also soil erosion
increase
Relative proportion of sand silt and
clay(particle size distribution)-texture• Clay - < 0.002 mm dia
• Silt - 0.002 - 0.05 mm dia
• Sand - 0.05 - 2 mm dia
• >2 mm- gravel
Effect of texture on erosion
Coarse texture• More sand• Light soil• Less erosion• Easily detachable but
difficult to transport
Fine texture• More clay and silt• Heavy soil• More erosion• Silt is easily detachable and
transportable• Clay not easily dispersed
but low infiltration and hence more run off and erosion
Soil structure
• Arrangement/grouping of soil particles
• Granular-more infiltration and less runoff.
• Compact soil-less infiltration and more runoff
SOIL STRUCTURE
SOIL ORGANIC MATTER• Plant and animal residues in various stages
of decomposition• Provide ground cover, sponge,less
evaporation• Increase permeability & water holding
capacity and reduce erosion• Life of soil, Improve structure• Sandy soil-2%• Clay and silt-3%
SOIL PERMEABILITY
• Ability of soil to allow air and water to move through soil.
• High permeable-less erosion and less run off
EROSIVITY
potential ability of rain
to cause erosion for a
given soil condition
ERODIBILITY
Susceptibility of soil to erosion and it depends on the physico-chemical characteristics of the soil & land and crop management factors.
Agronomic Vs Mechanical• Slow establishment• Long life• Low cost• Protective• Remunerative• Productive• Self multiplicating• Soil forming• Less skills• Conserve bio diversity• Eco friendly
• Fast result• Less life• High cost
Biologic and agronomic• Crops or Vegetation• Agronomic practice• Required even in areas where mechanical
measures are adopted for uniform infiltration and moisture distribution
TIMELY SOWING/CANOPY MANIPULATION
• Maximum erosion when the soil is bare without any crop cover.
• Establish the crop as early as possible.
Closer spacings.
Maize June 25 July 1 July 7
Canopy(july 30)
48% 20% 15%
Splash produced
14.5 g 18.4g 20.5g
yield Max Min
CONTOUR FARMING
Contour farming
CONTOUR FARMING
• Ploughing,seeding,planting,interculture in contours
• Easy effective and low cost• Forms ridge and furrows• Most effective in slopes upto 2- 6% slope• Consrve moisture,reduce erosion increase
production
Inter Cropping
• Growing two or more crops simultaneously in the same field following specific row or lne arrangement.
• Effective land use,resource use.
Inter Croppingsystem Yield(q/ha) Inter crop yield
Maize 28.6Maize+pigeonpea 28.2 6.2Sorghum 34.4Sorghum+pegion pea
33.5 5.5
Sorghum 33.5
Sorghum+greengram 30.8 7.3
POST-1ST YEAR
POST-2ND YEAR
INCREASING CROPPING INTENSITY
Strip cropping
Strip cropping• Alternate rows of erosion permitting and
resisting crop.
• Planted on contour for water erosion control.
• Against prevailing wind direction for wind erosion control.
• Usually a strip of cereal with pulse is alternated.
MIXED CROPPING
Rubber + Coffee + Cardamom
çÕøáÕcÞÉÈ¢Root distribution
MIXED CROPPING
• Small holding does not permit strip crop• One main crop and one subsidiary crop• Provide good land cover• Different root zones• Ensure at least one crop in adverse climatic
conditions.
Conservation tillage
• Tillage is the mechanical manipulation of the soil to create necessary soil conditions congenial for plant growth.
• Conservation tillage –minimum disturbance to top soil.
• Zero tillage, minimum tillage, mulch tillage• 30% of crop residue cover is maintained.
Conservation tillage
• Conservation tillage is any system that reduces the number of tillage operations maintains residue cover on the soil surface, and reduces the losses of soil and water relative to conventional tillage. It is a set of innovation technologies including no-till and various reduced or minimum tillage systems such as mulch tillage, strip tillage, and ridge tillage. Reduced or minimum tillage includes any system in which a soil is disturbed less than in conventional tillage but more than in no-till.
Conservation tillageNo-till and reduced-tillage farming leaves old crop residue on the ground instead of plowing it into soil. This covers the soil, keeping it in place. Here, corn grows up out of a “cover crop.”
Figure 8.16f
Reduces erosion
Saves fuel
Cuts costs
Holds more soil water
Reduces soil compaction
Allows several crops per season
Does not reduce crop yields
Reduces CO2
release from soil
Can increase herbicide use for some crops
Leaves stalks that can harbor crop pests and fungal diseases and increase pesticide use
Requires investment in expensive equipment
DisadvantagesAdvantages
Trade-Offs
Conservation Tillage
ssPhthen •Icns\m¨n•BStemSIw•sN¶n\mbIw•\oeAacn•sImSpthen•sN¼c¯n•AK¯n•ImämSn•kp_m_qÄ•sPt{Sm^•ioas¡m¶•Icn§men•Idnth¸v
Gliricidia sepium
Mulching
• Plant residues or other materials over soil surface.
»ADVANTAGES
Mulching
Properties of plants to be selected as barriers
• Erect,stiff uniform,dense permanent hedge• Perennial• Not to Spread as weed• Repel rodents• Deep penetrating roots• Sprout new tillers• Not compete with crop• Farmer friendly• Bio mass to be economic value
Cover crops
Calopo
S.hamata
Stylosanthes guinenesis
Siratro
Puero
Centro
Subabul
hr£h¡cWw
•¹mhv•amhv•Bªnen•PmXn•IpSw]pfn•IS¹mhv•Iqhfw•th¸v•]eI¸¿m\n
•B¯•Rmh•t]c•]pfn•D§v•ISp¡•Xm¶n•càNµ\w•Ipangv•]qhciv•kt¸m«
MECHANICAL/Engineering measures
ConceptIntercept long slope into shorter ones.
Does not allow to reach critical velocity.
Reduce/alter degree of slope.
Increase the time of concentration/opportunity time.
LAND LEVELLING/GRADING
LAND LEVELLING/GRADING
• Reshaping the land to a planned grade.• Uneven- No uniformity in irrigation
waterappliction,fertilizer distribution etc.• It enhances irrigation water use efficiency• Low r.f areas reduce run off & max infiltration
LAND LEVELLING/GRADING
• Criteria for land levellig– Soil (depth,texture,infiltration)– Topography (slope)– Cropping pattern(kind of crop,irrigation,returns)– Rainfall– Desire of farmers.
Bunding
• It is an embankment of suitable cross section constructed across the slope to break the slope length. These are the best for ground water recharge.– Contour bunding.– Graded bunding.
Contour bunding
Contour bunding
• Along the approximate contour• Suitable from 2-6% slope,< 800 mm r.f,and
relatively permeable soils.• Is adopted where leveling is impossible for
cost
STONE PITCHED CONTOUR BUND (PUERTORICCAN TYPE CONTOUR
TERRACE WALL)
Top width including pitching: 45 to 50 cm
Thickness of pitching: 15 to 22 cm
Side slope Uphill side of earth
fully: 1.5:1 Downhill side: 1:5 to
1:3 Foundation: 15 to 20
cm
Graded bunding
6-10 % slope Or Clay soil Or rainfall more than 800mm
Safely dispose run off Drainage channel
Merits & Demerits Page 16 ofyr text
Bench terracing
Step like fields by half cutting and half filling 6-33%slope. Or up to 50% In lower slopes for uniform water impounding
LAY-OUT OF BENCH TERRACE
Types of bench terraces
Suitability
Type Slope Soil type Rain fall,mm
Level 8-50 % Medium to deep
<2500-3000
Inward sloping
8-50 % Medium to deep
<2500-3000
Outward sloping
8-50 % Shallow <1200
Puertoricantype
8-50 % Shallow to deep
<1500
Puertorican Type Terrace/California type• Soil is not disturbed for making a terrace in
a single stroke or time• A hedge of suitable grass is planted in a
single or double row on contour at pre-determined spacing.
• The interspace between the two hedge lines of grass planted is cultivated and tilled to take crops.
• The tilled soil slowly moves towards the vegetative hedge and gets deposited against this barrier.
• The process continues for 3 to 4 years till it becomes level .
• Guatemala (Tripsacum laxum) and Hybrid Napier have been found effective for this purpose in the Nilgiris.
• This is much cheaper and does not disturb the top soil.
Conservation bench terracing
Strip terraces
• With lesser terrace width of 1-1.5 m• Design
– Maximum depth of cut (D)– Maximum admissible cut for given slope– Width of terrace.
1.Terrace spacing
2.Terrace gradient
3.Terrace cross section
NON ARABLE LAND CONSERVATION
MEASURES
Diversion drain
Contour trenching
– Break slope length– Reduce erosive velocity– Reduce run off– Retention of water
Contour trenching
CCT SCT
Crib structures
Contour Watling
DRAINAGE LINE TRTEATMENT
Check dams
Functions of check dam
Reduce the channel gradient
Reduce velocity of flow and silt carrying capacity
Percolation & ground water recharge
Promote vegetation growth in channels.
Components of check dam
Spill way to carry the flowAnchoring to side and bottomApron that absorb impact of falling water
Check dams
Temporary
Semi permanent
Permanent
Brush wood dams
XS-b-W-IÄ (sN¡v Umw)
BRUSH WOOD
XS-b-W-IÄ (sN¡v Umw)
\oÀNmÂ- kwc-£W {]hÀ¯-\-§Ä
Semi permanent
Permanent structures
• Where other inadequate or impractical
• Volume of peak run off is very high
• Sites where frequent maintenance not
possible
• High degree of risk for life/property
Permanent structures, only if
• Help in stabilizing gully and store water
• Adequate to handle Qp
• To be constructed with permanent
material
XS-b-W-IÄ (sN¡v Umw)
\oÀNmÂ- kwc-£W {]hÀ¯-\-§Ä
Gabion retaining wall
Wind erosion
Wind erosion, also known as eolian erosion, is a dynamic process by which soil particles are detached and displaced by the erosive forces of the wind. Wind erosion occurs when the force of wind exceeds the threshold level of soil’s resistance to erosion.
Causes of wind erosion
• crushed or broken soil surface crusts during windy periods;
• a reduction in the plant cover, biological crusts, and litter, resulting in bare soil;
• a decrease in the amount of organic matter in the soil, causing decreased aggregate stability;
• long, unsheltered, smooth soil surfacesDRY soil conditions-Arids & semi arids
EFFECTS OF WIND EROSION
• REMOVAL OF TOP SOIL• SCALDING ON SOIL SURFACE• ROOT EXPOSURE• SOIL TEXTURAL CHANGES ATTRITION AND
WINNOWING• EXTENSION OF DESERTS• HIGH DUST CONCENTRATION IN ATMOSPHERE
CAUSING HEALTH HAZARDS• DAMAGE TO ROAD, RAIL, BUILDING• SAND DEPOSITS
Wind erosion control
Shelter belt
148
77.2% aªp-]m-fn-I-fnÂ
22.4% `qKÀ`-¯nÂ
0.4% e`y-amb Pew
1
2
97.4% ISÂshÅw
2.6 % ip²-Pew
Pew {]]-©-¯nÂ
149
shÅw! shÅw!!
1 In.{Kmw Dcp¡v \nÀ½n-¡m³ þ 150 enäÀ
1 In.{Kmw IS-emkv \nÀ½n-¡m³ þ 900enäÀ
1 In.{Kmw kn´-änIv ss^_À þ 2000 enäÀ
1 In.{Kmw Mutton \nÀ½n-¡m³ þ 70000enäÀ
1 I¼q-«À \nÀ½n-¡m³ þ 30000 enäÀ
1 S¬ s\Ãv \nÀ½n-¡m³ þ 4000 enäÀ
1 enäÀ Milk \nÀ½n-¡m³ þ 900 enäÀ
• The water storage capacity of a particular region remains the same
• The consumption increases
with increase in population
corresponding to changes in life style
RAIN WATER HARVESTING
• Kerala state is receiving 80-90 % of rain fall in a period of 5-6 months and for the rest 6-7 months it is under water insecurity. The fun about Kerala is, 8500 million cubic metre water is excess in monsoon and 7200 million cubic metre deficit in summer. This demands a very meticulous planning for rain water harvesting in the state
The land of 44 rivers is only a fallacy as the total amount of water that all the rivers contain together is less than 2/3rd of Godavari. We have no major rivers and only 4 medium and 40 minor rivers. The largest river is Periyar with a length of 240 km. Kerala is having only < 2 % area under irrigation.
153
tIc-f-¯nse `q{]-IrXn
600 In.aoäÀ \ofw
70 In.aoäÀ hoXn
\Zn-I-fpsS i-cm-icn\ofw : 100 In.aoäÀ
tIcf kmlNcy¯n \oÀ¯Sm[njvTnX
hnIk\¯nsâ {][m\yw
Physiographically it is demarcated as 48% high land, 42 % mid land and 12% low land. Due to these features of topography the water gets very little time to infiltrate into the soil and the entire rain fall takes very short time to reach the sea. Due to this reason only 6-12% rain is recharged in to the ground in Kerala. With this, the state has to support a population density of 819/km2.
Rainfall availability
• Reeipt-400 million hectare meter –69 million surface water–45 million ground water–This 114 million is 29%–The rest 71% goes to the sea or get evaporated
C´y þ {]XnioÀj Pee`yX
• Stress 1700 m3• Water scarce 1000 m3
1955 5300 M3
1990 2200 M3
2005 2000 M3
2025 1465
2050 1235
Sl No. District /Assessment Unit Categorisation for future ground water development (Safe/ Semi-Critical/Critical/Over-exploited)
1 Kollengode Critical
2 Nenmara Safe
3 Thrittala Critical
4 Ottapalam Safe
5 Alathur Safe
6 Pattambi Safe
7 Palakkad Critical
8 Attappadi Semi-critical
9 Kuzhalmannam Safe
10 Mannarkkad Safe
11 Chittur Over exploited
12 Sreekrishnapuram Semi-critical
WATER CYCLE
Water harvesting
• Is the collection, storage and conservation of rainfall for its productive use in irrigation, domestic and industrial uses.
• Is the technique of collection and storage of rain water that runs off a natural or manmade catchment such as watersheds rooftops, compounds, rocky surfaces or hill slopes
Water harvesting techniques
• 1.In situ - where rain fall is received
• 2.Surface water harvesting
• 3. Roof top
2.Surface water harvestingDug outsFlt areas
Embankment typeHilly areas
Dams
RWHS
• Catchment• Gutter• Drain pipes• First flush• Filter unit• Storage tank• Collection sump and
pump unit
Underground cistern
Just like an underground tank but with more storageArid regions for reducing evaporation loss.
Artificial RechargeArtificial Recharge : Augmentation of Ground water reservoir at a rate exceeding that under natural condition
ARTIFICIAL RECHARGE BY SUBSURFACE METHODS
Pond/ tank with shaftRecharge pitRecharge trench Recharge well Injection wellSub surface dams
Dug well recharge Dried up dug wells/ wells in
which water levels have declined can be recharged
Source of recharge can be rain water from storm/tank/canal/
Roof top Recharge water should be passed
through desilting chamber, after desilting the recharge water is taken to bottom of well/ below the water level.
Periodic chlorination.
Dug well recharge
Abandoned Quarries/ Mine pits
Recharge shaft/ Injectionwells
Efficient and cost effective structures
Back filled with inverted filter
Suited for deep water levels (upto 15m)
Silt water can be used
HOW much water do I use ???
Use Litres/person
Drinking 3
Cooking 4
Bathing 20
Flushing 40
Washing-clothes 25
Washing Utensils 20
Gardening 23
Total 135
Consumption range 50 Ltrs/300 ltrs per person per day
A dripping tap could waste as much as 90 litres a week.
Brushing your teeth with the tap running wastes almost 9 litres a minute. Rinse out from a tumbler instead.
Cool water kept in the fridge means you won't have to run the tap for ages to get a cold drink.
Don't use your washing machine until you've got a full load. The average wash needs about 95 liters. A full load uses less water than 2 half loads.
Every time you boil an egg save the cooled water for your houseplants. They'll benefit from the nutrients released from the shell.
Fit a water saving device in your cistern and save up to three litres a flush.
Grow your grass a little longer. It will stay greener than a close mown lawn and need less watering
DRIPS
And human dwelling conditions could not get worse