Transcript Trees and Their Role in Storm Water Management

MENANAM POHON
UNTUK
MEMANEN AIR HUJAN
Soemarno - psdl ppsub 2013
MENANAM POHON
UNTUK
MEMANEN AIR HUJAN
Kombinasi teras bangku dan vegetasi pohon
untuk memaksimumkan hasil panen air hujan
Sumber: www.thecottagekey.com/watershed.htm
Siklus air hujan mengisyaratkan besarnya
peluang untuk memanen air hujan
Karakter pohon dapat dimanfaatkan untuk
memanen air hujan dan energi matahari
sebanyak-banyaknya
SIKLUS HIDROLOGI
The hydrologic cycle over land includes interception of
precipitation by plant foliage and wood, throughfall and
stemflow, transpiration, soil evaporation, canopy evaporation,
infiltration, runoff, soil water, aquifer recharge, and snow.
These are directly linked to the biogeophysics and also affect
temperature, precipitation, and runoff.
Diunduh dari sumber:
http://www.cesm.ucar.edu/models/clm/hydrologic.html ….. 31/10/2012
EVAPOTRANSPIRASI
The total evapotranspiration (ET) can be broken down into the Tr
is transpiration, Ei interception evaporation, and Es evaporation
from the bare soil and forest floor litter. On an annual basis in a
forested environment, transpiration is the dominant component
of ET, followed by interception evaporation and then bare-soil
evaporation. However, during precipitation events, interception
evaporation becomes the dominant component of ET during
rainfall and during the hours immediately following precipitation.
Diunduh dari sumber: http://www.grin.com/en/doc/268148/observations-of-thetransient-characteristics-of-the-hydrological-balance…..31/10/2012
INTERSEPSI
Interception refers to precipitation that does not reach the soil,
but is instead intercepted by the leaves and branches of plants
and the forest floor. It occurs in the canopy (i.e. canopy
interception), and in the forest floor or litter layer (i.e. forest floor
interception. Because of evaporation, interception of liquid water
generally leads to loss of that precipitation for the drainage
basin, except for cases such as fog interception.
Diunduh dari sumber: http://www.answers.com/topic/interception…..
3110/2012
Akar Pohon
Tree species are not necessarily "deep-rooted" or "shallowrooted" -- certain species are more or less sensitive to various
levels of moisture, oxygen, and minerals. Often roots will
"bounce" off a soil hardpan or a high water table, forming
surface roots where other species may not be able to live at all.
Diunduh dari sumber: http://www.oakwilt.com/articles13001/anatomy2.html …..
31/10/2012
Trees: The Original Multi-taskers
Their beauty inspires
writers and other
artists.
• Provide social, ecological, and economic benefits
• Their leaves and roots clean the air we breathe
and the water we drink
Benefits of Trees in Urban Areas
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Save Energy; Improve air quality
Extend life of paved surfaces
Increase traffic safety
Increase real estate values
Increase sociological benefits
Protect our water resources
All water is part of this cycle
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Storm Water dan Siklus Hidrologi
• Urbanization dramatically alters the hydrologic cycle
– Increases runoff
– Increases flooding frequency
– Decreases infiltration and groundwater recharge
• Nationwide impervious surfaces have increased by 20%
in the past 20 years
More Trees Means Less Runoff
Some Statistics
For every 5% of tree cover added
to a community, storm water is
reduced by approximately 2%
• Fayetteville, Arkansas: increasing tree canopy from
27-40% reduced their storm water runoff by 31%
• South Miami residential study found that a 21%
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existing tree canopy reduces the storm water runoff
by 15%
Bagaimana pohon mengendalikan
“Stormwater”?
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Above ground effects:
– Interception, evaporation and absorption of precipitation
Ground surface effects: Temporary storage
Below ground effects: Infiltration, permeation and filtration
Infiltrasi dan perkolasi air-hujan dalam tanah merupakan
dua proses hidrologis yang sangat diperbaiki oleh adanya
vegetasi pohon
EFEK POHON TERHADAP LINGKUNGAN DI
ATAS TANAH
Absorption of a small portion
into leaves or stems
• Intercept rainwater on leaves, branches and trunks
– slowing its movement
• Evaporation of some of this intercepted
precipitation of the tree surfaces
Efek Pohon terhadap Lingkungan Bawah Tanah
Roots and trunk bases of mature trees
tend to create hollows and hummocks on
the ground
Leaf litter and other organic matter can hold
precipitation and stemflow on a site, reducing the
amount and peak rates of runoff
Efek Pohon terhadap
Lingkungan Bawah Tanah
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Organic material from leaf litter and other tree detritus tends
to increase infiltration rates by increasing pore spaces in soil
Organic material also increases the moisture-holding capacity
of these sites
Root mats of trees also tend to break up most soils further
improving infiltration and moisture-holding capacity
EFEK LINGKUNGAN-BAWAH-TANAH
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Deep roots tend to improve the rates of percolation of water
from upper soil horizons into lower substrates
Trees take up water through their roots that is eventually
transpired onto leaf surfaces and evaporated
Tree roots act as natural pollution filters (biofilters) using
nitrogen, phosphorus and potassium
TAJUK POHON - KENYAMANAN
• Set to protect a community’s green infrastructure and
maximize the environmental benefits
• For metropolitan areas east of the Mississippi
– Average tree cover for all land use 40%
– Suburban residential
50%
– Urban residential
25%
– Central business districts
15%
MULTIPURPOSES …?
Ruang terbuka hijau – Taman pohon buahbuahan
COMPLICATING FACTORS
• Presence of soil compaction
• Presence of soil textural discontinuity
– Has the site been disturbed in the past?
• Management of the ground surface
– Is litter layer removed?
– Is soil surface exposed in winter?
– How much of the surface is like a natural forest?
(number and size of trees)
PERGERAKAN LENGAS TANAH
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Forces affecting the energy of soil water
– Matric force (absorption and capillary)
– Gravity
– Osmotic forces
Field Capacity is the amount of water held in the soil after
gravitational water had drained away
Movement of water is the soil is controlled :
– Gravitational forces if saturated
– Matric forces if unsaturated
Tanah mempengaruhi Infiltrasi air hujan
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Infiltration is the mode of entry of all water into the soil
Rate of infiltration determined:
– Initial water content
– Surface permeability
– Internal characteristics of the soil
Intensity and duration of rainfall
Temperature of soil and water
Tanah mempengaruhi Infiltrasi
Soil compaction reduces the
infiltration rate
• Microrelief under trees provides catchment basins
during heavy rains
• Removal of litter layer reduces the infiltration rate
• Forest soils have a high percentage of macropores
• The frost type found in forest soils promotes
infiltration year-long
PENTINGNYA SERESAH
DI PERMUKAAN TANAH
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Absorbs several times its own weight
Breaks the impact of raindrops
Prevents agitation of the mineral soil
Discourages formation of surface crusts
Increases soil biotic activity
Increases incorporation of organics
Slows down lateral movement of water
POROSITAS TANAH
• Develop in old root channels or from burrows and
tunnels made by insects, worms or other animals
• Lead to better soil structure
• Increases organic matter incorporation
• Increases percolation rates and root penetration
TANAH DI BAWAH TEGAKAN HUTAN
• Granular
– Found in woodland soils with litter
– May be more permeable
• Honeycomb
– Has loose porous structure
– Found in highly aggregated soils and also
formed in organic layers and litter layers
AIR-TANAH-TANAMAN
The proportion of the soil occupied by water and air is referred to
as the pore volume. The pore volume is generally constant for a
given soil layer but may be altered by tillage and compaction.
The ratio of air to water stored in the pores changes as water is
added to or lost from the soil. Water is added by rainfall or
irrigation. Water is lost through surface runoff, evaporation
(direct loss from the soil to the atmosphere), transpiration
(losses from plant tissue), and either percolation (seepage into
lower layers) or drainage.