MENANAM POHON UNTUK MEMANEN AIR HUJAN GROUNDWATER Soemarno - psdl ppsub 2013

MENANAM POHON UNTUK

MEMANEN AIR HUJAN

GROUNDWATER

Soemarno - psdl ppsub 2013

GROUNDWATER USE AND RECHARGE

There is a substantial amount of ground water recharge from surface water and ground water used to irrigate

agricultural crops. Some of the irrigation water flowing in unlined ditches and some of the water that is applied to irrigate crops infiltrates into the soil, percolates through the root zone and recharges the ground water basins

Ground waterGround water occupies the zone of saturation. Ground water moves downward through the soil by percolation and then

toward a stream channel or large body of water as seepage. The water table separates the zone of saturation from the zone of

aeration. The water table fluctuates with moisture conditions, during wet times the water table will rise as more pore spaces are occupied

with water. Ground water is found in aquifers, bodies of earth material that have the ability to hold and transmit water. Aquifers can be either unconfined or confined. Unconfined (open) aquifers

are "connected" to the surface above.

AQUIFERS

The rate of ground water flow depends on the permeability of the aquifer and the hydraulic

gradient. Permeability is affected by the size and connectivity of pore spaces. Larger, better

connected pore spaces creates highly permeable earth material. The hydraulic gradient is the

difference in elevation between two points on the water table divided by the horizontal distance

between them.

The rate of ground water flow is expressed by the equation:

Ground water flow rate = permeability X hydraulic gradient

Groundwater flow rates are usually quite slow. Average ground water flow rate of 15 m per day

is common. Highly permeable materials like gravels can have flow velocities of 125 m per

day.

GROUNDWATERGround water in an aquifer is under pressure called hydrostatic

pressure. Hydrostatic pressure in a confined aquifer pushes water upward when a well is drilled into the aquifer.

The height to which the water rises is called the peizometeric surface. If the hydrostatic pressure is great enough to push the peizometeric surface above the elevation of the surface, water

readily flows out as an artesian well.

www.uwsp.edu/geo/faculty/ritter/geog101/textb...

PROFIL LENGAS TANAHFollowing an infiltration event, in which the entire soil profile becomes

saturated with water (indicated by a solid vertical line corresponding to a water saturation of 1.0), water will drain from the soil profile primarily

under the influence of gravity (i.e., the pressure gradient is negligible). Assuming that no additional water enters the system, the soil water

saturation profile at static equilibrium (dashed line) will decrease from a value of 1.0 in the saturated zone (groundwater and capillary fringe) to a value corresponding to field capacity below the root zone. In effect, the

soil water profile is analogous to a soil water retention (pressure-saturation) curve. Hence, the solid and dashed lines represent the limits

in water content (saturation) between which soil water percolation occurs in soils overlying an unconfined aquifer.

www.informaworld.com/smpp/95829679-70617050/c...

Water is recharged to the ground-water system by percolation of water from precipitation and then flows to the stream through the

ground-water system.

Sumber: ga.water.usgs.gov/edu/earthgwdecline.html

Water pumped from the ground-water system causes the water table to lower and alters the direction of ground-water movement.

Some water that flowed to the stream no longer does so and some water may be drawn in from the stream into the ground-

water system, thereby reducing the amount of streamflow.

.

Contaminants introduced at the land surface may infiltrate to the water table and flow towards a point of discharge,

either the well or the stream. (Not shown, but also important, is the potential movement

of contaminants from the stream into the ground-water system.)

Water-level declines may affect the environment for plants and animals.

For example, plants in the riparian zone that grew because of the close proximity of the water table to the land surface may not

survive as the depth to water increases.

The environment for fish and other aquatic species also may be altered as the stream level drops.

11

The fate of applied water can be better understood if the total hydrologic cycle is understood first. The hydrologic cycle describes the movement of water through its different forms and locations. Important processes

in the hydrologic cycle are: 1. Evaporation -the transformation of liquid water into water vapor from

free water surfaces. 2. Precipitation (rain or snow).

3. Runoff -water moving overland or in a river or stream. 4. Infiltration -the movement of water into the soil.

5. Percolation -the movement of water through the soil. 6. Freezing - liquid water turning into ice

7. Thawing - melting of ice 8. Transpiration - the movement of water vapor out through plant/animal

tissue surfaces into the atmosphere.

SIKLUS HIDROLOGI DI ALAM

Sumber: www.forestry.ubc.ca/.../forwady/forwady.htm

http://www.forestry.ubc.ca/.../forwady/forwady.htm

HUTAN DAN SIKLUS HIDROLOGI

The surface water in a stream, lake, or wetland is most commonly precipitation that has run off the land or flowed through topsoils to subsequently enter the waterbody. If a surficial aquifer is present and hydraulically connected to a surface-water body, the aquifer can sustain surface flow

by releasing water to it. In general, a heavy rainfall causes a temporary and

relatively rapid increase in streamflow due to surface runoff. This increased flow is followed by a relatively slow

decline back to baseflow, which is the amount of streamflow derived largely or entirely from groundwater.

During long dry spells, streams with a baseflow component will keep flowing, whereas streams relying

totally on precipitation will cease flowing. Generally speaking, a natural, expansive forest

environment can enhance and sustain relationships in the water cycle because there are less human modifications to

interfere with its components.

A forested watershed helps moderate storm flows by increasing infiltration and reducing overland runoff.

Further, a forest helps sustain streamflow by reducing evaporation (e.g., owing to slightly lower temperatures in

shaded areas). Forests can help increase recharge to aquifers by allowing more precipitation to infiltrate the

soil, as opposed to rapidly running off the land to a downslope area.

Forests and prairies rarely yield runoff regardless of steepness, even when frozen

Forested areas provide storm water protection and protect the quantity and

quality of groundwater

Penebangan pohon berdampak meningkatnya ancaman banjir

16

Groundwater –Surface Water Flows

Black Earth Creek Study

• Black Earth Creek receives 80% of its water from groundwater

• Main recharge occurs in spring and fall• Recharge from the agricultural uplands is highly variable• Forested slopes are significant recharge areas

Wooded hill slopes generate no

significant runoff

Effects are greatest during the growing seasonEffects are greatest on sites whose soils are

relatively impermeable

Pohon memperbaiki Kapasitas infiltrasi lapisan tanah permukaan

The impact of urban trees on hydrology is extremely variable and complex, in general increases in tree cover and tree size over a

site will result in reduced total runoff amounts and peak runoff rates.

Pohon dan Storm Water

• Trees have a relatively greater effect on smaller storm runoff amounts than on large storm events

• Surface and below-ground effects on runoff are much more significant than the above-ground effects

• All of the effects on runoff are greatest when urban trees are large and well-established on undisturbed sites

Contact Information:Mindy Habecker

Dane County UW-Extension [email protected]

Pohon memperbaiki kenyamanan thermal lingkungan sekitarnya

mailto:[email protected]

22www.cropscience.org.au/.../1399_shahbazkhan.htm

23

Sumber: www.ene.gov.on.ca/envision/gp/4329e_1.htm

http://www.ene.gov.on.ca/envision/gp/4329e_1.htm

Sumber: www.aucklandcity.govt.nz/.../hgiapp15.asp

Typical root systems are made up of a combination of four types of roots: major lateral roots sinker roots woody feeder roots non-woody feeder roots.

25

Sumber: www.dof.virginia.gov/urban/landscape-manual.shtml

Tajuk pohon mengamankan lingkungan di sekitarnya, di atas tanah dan di bawah tanah.

http://www.dof.virginia.gov/urban/landscape-manual.shtml

Tree and Root System on Bank of Darling River, Kinchega National Park, Outback, New South

Wales, Australia

Sumber: en.allexperts.com/q/Trees-739/Douglas-Fir-Roo...

29www.forestry.ubc.ca/.../forwady/forwady.htm

GROUNDWATER RECHARGE

http://en.wikipedia.org/wiki/Groundwater_recharge

Groundwater recharge or deep drainage or deep percolation is a hydrologic process where water

moves downward from surface water to groundwater.

This process usually occurs in the vadose zone below plant roots and is often expressed as a

flux to the water table surface.

Recharge occurs both naturally (through the water cycle) and through anthropogenic processes (i.e., "artificial groundwater

recharge"), where rainwater and or reclaimed water is routed to the subsurface.



Processes

Groundwater is recharged naturally by rain and snow melt and to a smaller extent by surface water (rivers and lakes). Recharge may be impeded somewhat by human activities including paving, development, or logging. These activities can result in loss of topsoil

resulting in reduced water infiltration, enhanced surface runoff and reduction in recharge. Use of groundwaters, especially for irrigation, may also

lower the water tables. Groundwater recharge is an important process for sustainable groundwater management, since the

volume-rate abstracted from an aquifer in the long term should be less than or equal to the volume-rate

that is recharged.

Recharge can help move excess salts that accumulate in the root zone to deeper soil layers, or

into the groundwater system. Tree roots increase water saturation into groundwater reducing water runoff. Flooding temporarily increases river bed

permeability by moving clay soils downstream, and this increases aquifer recharge.



http://upload.wikimedia.org/wikipedia/commons/8/80/Surface_water_cycle.svg

Trees and groundwater

http://savanna.org.au/savanna_web/publications/savanna_links_issue12.html?tid=29993

This question of water sources for trees is not easy to answer. During the wet season, rainfall

becomes surface run-off or enters the soil. Given the high rainfall of the Top End, the soil’s

capacity to soak up water is soon exceeded and water drains from the soil recharging shallow groundwater aquifers or flowing through into

streams. During the dry season therefore, trees could be using soil water exclusively, or

groundwater, or a mixture of both.Excavations of root systems have revealed a

concentration of roots in the top 1-1.5 m of soil.

Further, large and small trees are able to flush their canopies with new leaves during

September and October, periods when upper soil moisture levels (top 2 m) are at a minimum and

the water table is around 10 m below the surface. This leaf growth requires a considerable amount of water and small trees do not have deep root

systems. This suggests they have adequate access to water from the soil alone.



Hypothetical root distribution for a mature Eucalypt tree growing in the Darwin region. Figure modified from that of

Kimber (1974) The root systems of Jarrah. Forests Department of Western Australia, Research Report No. 10,

5 pp .



Surplus groundwater?

As part of the TS-CRC project, CSIRO scientists Drs Tom Hatton and Peter Cook constructed a

water balance for the research catchment.

Using changes to aquifer CFC concentrations with depth below ground, the rate of recharge

was estimated to be 200 mm year-1. This includes a 20 mm ‘groundwater surplus’.

An error analysis suggests that this surplus may be as small as zero, or as large as 140mm.

If we assume it is about 20 mm for a catchment such as the Howard River, this represents a

sustainable yield of at least 2500 Ml of water per year.

While we currently think groundwater extraction is unlikely to threaten the eucalypt savanna,

other ecosystems may be vulnerable, such as spring-fed monsoon vine forests.



Hydrological cycle and water balance of Top End tropical eucalypt savanna

deep drainage from tree belts

. An ecological optimality approach for predicting deep drainage from tree belts of alley farms in water-limited environments

Tim Ellis, Tom Hatton, Ian Nuberg. Agricultural Water Management.Volume 75, Issue 2, 15 July 2005, Pages 92–116.

The clearing of natural vegetation for agriculture in southern Australia has increased deep drainage, led to increased

groundwater recharge and, hence, the salinisation of land and streams.

Alley farming systems, comprising alternate belts of trees and crops, have been proposed for reducing deep drainage but their effectiveness is unknown. This paper describes an application of

ecological optimality theory to estimate the equivalent no drainage (ENOD) width B (m) for a tree belt.

The relative drainage RD from an alley farm, compared to conventional agriculture is, therefore, 1 − B/W, where W is the

centre spacing of the belts. We present a method for estimating BLA from the leaf area per unit length of belt LLA (m2 m−1), divided by the leaf area index LAI (m2 m−2) of nearby natural vegetation.

Preliminary evaluation of BLA showed good agreement with BWB measured from water balance and BDD measured from deep

drainage. The estimation of BLA for calculation of RD allows rapid estimates of the relative drainage reduction expected from alley

farms in water-limited environments.

Schematic diagram of a typical tree belt vegetation community of an alley farm in a water-limited environment where Dc is the deep drainage under the crop/pasture. The ENOD concept is a ‘step’

approximation (bold dashed line) to the likely actual deep drainage (curvilinear line) such that areas a + b = c.

. An ecological optimality approach for predicting deep drainage from tree belts of alley farms in water-limited environments

Tim Ellis, Tom Hatton, Ian Nuberg. Agricultural Water Management.Volume 75, Issue 2, 15 July 2005, Pages 92–116.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&docid=-RzXbGvOUWsV1M&tbnid=a0mtQBNiTJuY8M:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0378377404003543&ei=-bVsUtfRL8G3rgfhg4CAAg&bvm=bv.55123115,d.bmk&psig=AFQjCNEtjDfrJ-8PnQzshSYp-nY3Mw8QJg&ust=1382941916824881

Where ground water occurs

http://pubs.usgs.gov/gip/gw_ruralhomeowner/

Rock materials may be classified as consolidated rock (often called bedrock) and may consist of sandstone,

limestone, granite, and other rock, and as unconsolidated rock that consists of granular material such as sand,

gravel, and clay.

Two characteristics of all rocks that affect the presence and movement of ground water are porosity (size and

amount of void spaces) and permeability (the relative ease with which water can move through spaces in the rock).



Consolidated rock may contain fractures, small cracks, pore spaces, spaces between layers, and solution openings, all of

which are usually connected and can hold water.

Bedded sedimentary rock contains spaces between layers that can transmit water great distances. Most bedrock contains

vertical fractures that may intersect other fractures, enabling water to move from one layer to another.

Water can dissolve carbonate rocks, such as limestone and dolomite, forming solution channels through which water can move both vertically and horizontally. Limestone caves are a

good example of solution channels.

Consolidated rock may be buried below many hundred feet of unconsolidated rock or may crop out at the land surface.

Depending upon the size and number of connected openings, this bedrock may yield plentiful water to individual wells or be a

poor water-bearing system.



Unconsolidated material overlies bedrock and may consist of rock debris transported by glaciers or deposited by

streams or deposited in lakes.

It also may consist of weathered bedrock particles that form a loose granular or clay soil.

Well-sorted unconsolidated material can store large quantites of ground water; the coarser materials—sand

and gravel—readily yield water to wells.



Using Trees to Control Groundwater Recharge: How Many are Enough?

http://www.dpi.vic.gov.au/agriculture/farming-management/soil-water/salinity/using-trees-to-control-groundwater-recharge-how-many-are-enough

Trees are important in preventing groundwater recharge and are complementary to other methods, such as

establishing perennial pasture, improving crop productivity and natural regeneration.

Trees are recommended for land where either perennial pastures cannot b reliably established, will not persist or

will be unable to provide adequate protection from groundwater recharge.



How much water could trees use?

The reduction of groundwater recharge by vegetation depends on its ability to use or evaporate water from the soil. the deep

root systems and large, evergreen crowns of many native trees means they can use more water than other types of vegetation (e.

g pastures, crops, shrubs).Nevertheless, trees do not have an unlimited capacity to use water.

Evaporation of water from trees or any vegetation, depends upon three things:

1. Water - a tree can only use as much water as it has access to in the soil (soil moisture). Soil moisture varies throughout the year and is lowest during late summer and early autumn. The maximum water use by a stand of trees growing in recharge areas will be the annual rainfall. Surface run-off and recharge that occurs between root systems, however, reduces the potential water use.

2. Sunlight - the energy for evaporation comes mainly from the sun. In most parts of Victoria it has the potential to evaporate up to 1500 millimetres of water a year.

3. Leaf area - most evaporation takes place through the leaves. As a tree grows its leaf area increases and so does its water use.



How much water do trees use?The following information has come from recent research.

Table 1 Results of some Victorian investigations into water use by eucalypts growing on recharge.

Location (rainfall) Age (years)Tree water use-

litres per day and range (average)

Burkes Flat (450mm)

6 10-100 (30)

Warrenbayne (800mm)

20 0-160 (50)

Warrenbayne (800mm)

>100 10-450 (140)

Table 1 shows the variation in water use over a year by eucalypts on recharge zones. The lower figures areduring

rainy days in winter and the higher figures are in early summer before the soil moisture is depleted. Daily water use by a tree therefore can vary considerably throughout

the year. The averages over the year are given in brackets.Table 1 also shows that age (due to growing leaf area and root system) also has a significant effect on the ability of

trees to use water.



Table 2 shows the importance of stand density and water use. In a paddock the amount of water any one tree uses has little

significance in recharge control. What is mostimportant is the water use by the whole stand.

Table 2. Stand density and water use

Location Tree age (years)

Average tree water use -from Table 1(litres per

day)

Stand density(trees per hectare)

Stand water

use(mm)

Burkes Flat 6 30 200 200

Warrenbayne 20 10 20 35

Warrenbayne over 100 140 20 105



Opportunities for trees to control groundwater recharge

Since a tree's capacity to use water is limited, careful planning is required to ensure that trees are effective in controlling recharge. Planning must achieve a balance

between:1. the amount of water to be evaporated;2. the density of trees in the plantation;3. what is an acceptable delay before the control of

recharge is achieved.To calculate the approximate number of litres per day each

tree would have to average over the year, use this equation:

No. of Litres = water use required (mm a year) x 25

per day number of trees a hectare

This equation enables you to calculate whether or not you are 'asking too much' of your trees to achieve your required level of

recharge control.If the most water we can expect a mature tree to evaporate

averages 140 litres per day (Table 1), it follows that to use a given amount of water a minimum number of trees per hectare are

required. For example at least 100 trees per hectare are needed to use 500 nun of rain per year.

To reduce the amount of time to achieve a certain level of water use, more trees per hectare should be planted.



How many trees are enough?

Dense plantations (at least 500 trees a hectare) are clearly the best means of achieving rapid and effective control of

groundwater recharge. However, recharge control will not always be compatible

with other land management objectives, such as maintaining grazing or growing trees commercially.

Therefore the answer to the question of 'how many trees are enough to control recharge?' must begiven for each

general type of rural tree growing.



Protection and landscape plantings

Most tree growing in rural areas is for either protection (control of land degradation, stock shelter) or landscape (visual beauty,

wildlife habitat) purposes.

Dense plantations will generally be needed to meet theseobjectives. However establishment costs of these

plantations can be expensive, since no direct commercial returns are expected.

Assuming a stand density of at least 400 trees a hectare (5 x 5 metre spacing) is necessary for protection and landscape

plantings, it may take around 10 years for the trees to control groundwater recharge (depending upon rainfall and rate of

recharge).

Higher densities, can be relatively easily and cheaply achieved through direct seeding or fencing areas off to allow natural

regeneration.These techniques can significantly reduce the delay before achieving recharge protection.



Trees in pasture

There are two forms of tree growing in pasture that may play a role in the management of groundwater recharge

areas:1. agroforestry - where both the trees and pasture are

managed to provide a commercial return, and;2. low density protection plantings - where trees are

planted at a wide spacing to allow grazing to continue but close enough so that some, and perhaps eventually, complete recharge control is achieved.

Appropriate densities for tree growing over pasture are 20-200 trees a hectare. At the lower range, recharge control will only be very slowly achieved (50+ years) and will rely

on the trees not significantly affecting the evaporation from the pastures below.

At densities lower than 20 a hectare (23 x 23 metre spacing) the average daily water use to achieve a given level of annual evaporation issimply asking too much of

the trees.

How to Recharge Ground Water and Prevent Contamination?

http://kayjayr-akshay.blogspot.com/2012/05/how-to-recharge-ground-water-and.html

Rainfallis the main source of ground water recharge. Other sources include rechargefrom rivers, streams, irrigation water

etc. Rainfall is limited for a fixedduration, natural recharge of ground

water is restricted to a particular periodonly. Large volume of rainfall flows into the sea and is evaporated. Since wecannot depend on rains to recharge ground water we have to adapt

artifcialmethods that are low in cost, and easy to use.



Recharge by Dugwell Method:There are thousands of dug wells, which have either gone dry, or the water levels have declined considerably. These dug wells can

be used as structures to recharge the ground water reservoir. Storm water, tank water, canal water etc. can be diverted into

these structures to directly recharge the dried aquifer.



Rain garden to recharge ground water:

Rain garden is designed to hold rain water runoff from roof tops, drive ways, patios, or lawns. It contains native shrubs, perennials, plants etc. Every time it rains, water

runs off impermeable surfaces, such as roofs or driveways,collecting pollutants like particles of dirt,

fertilizer, chemicals, oil, garbage, and bacteria along the way. The pollutant-laden water enters storm drains

untreated and flows directly to nearby streams and ponds. Rain gardens collect rainwater runoff, allowing the water to be filtered by the vegetation and percolate into the soil recharging groundwater aquifers. This process filter out

pollutants.

The advantages of rain Garden are:

1. Improve the water quality by filtering pollutants.2. Pleasing appearance to the building.3. Preserves native vegetation.4. Provides strom water and flood control.5. Attracts bees, birds, insects.6. Maintenance is easy.7. Helps in ground water recharge.



Rain-gardens

:

Phytoremediation to recharge Ground water:

In addition to all other above methods planting and cultivation of woody trees help in replenishing ground

water conservation because the roots help in percolation of rain water deep into the soil and keep the water table

steady. Cultivation of trees not only enriches the quality of water but also raises the ground water table.

They also remove, transfer, stabilize, and/or destroy contaminants present in the soil and in the ground water.

They clean up contaminated soil, sludge and ground water.

This method of cleaning up ground water pollution and maintaining the water table and soil contaminants using

different species of plants and trees is a low cost, environmentally friendly and effective for a wide range of

chemicals such as pesticides, solvents,crude oil, poly aromatic hydrocarbons and metals etc.



Phytoremediation to recharge Ground water:



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MENANAM POHON UNTUK MEMANEN AIR HUJAN GROUNDWATER Soemarno - psdl ppsub 2013