1

Bahan Kajian MK. PSDALH

Smno.psdl.pdkl.ppsub.nop2013

MANAJEMEN AIR HUJAN

RAIN-GARDEN

TAMAN HUJAN

Maintain & replace infrastructure1. Infrastructure2. In place some time3. Pipers clog4. Impede storm

water flow5. Open ditches

gradually fill6. Vacuum and water

jet trucks7. Replace with BMP

https://www.facingthefuture.org/Curriculum/PreviewandBuyCurriculum/tabid/550/List/1/ProductID/28/Default.aspx#.UpsUGCdRWho

Improve stream water quality1. Streams impaired2. Streams may not

be suitable for certain aquatic life/human recreation

3. Monitoring/research useful-aid in stream quality

4. BMP. Bio retention area, debris catchments, bank restoration

5. Improve water quality

http://ccsummerresearch.blogs.wm.edu/2013/05/01/7444/

BMP improvement1. Restoration2. Habitat

Movement of water through a detention pond-wetlands system

(Martin and Smoot, 1986)

http://environment.fhwa.dot.gov/ecosystems/ultraurb/3fs5.asp

What is an impervious surface?1. Rainwater cannot

infiltrate2. More water

volume-runoff into storm drain

3. Storm water fee4. Median impervious

area of single family residential propertied 100-200 m2

http://iowacedarbasin.org/runoff/showMan.php?c1=2E-1

What is goal of storm water fee?1. Maintain

water quality2. Allow city to

comply – federal-state regulations-unfunded mandate

3. Flood damage reduction/drainage

4. Long term maintenance

Infiltrasi permukaan dapat dicapai melalui penggunaan strip penyangga rumput, sengkedan

bervegetasi, dan sistem perkerasan berpori.

Sistem infiltrasi seperti parit resapan, cekungan infiltrasi, dan zone bioretention (termasuk taman hujan) yang dirancang khusus untuk menangkap volume limpasan hujan dan transfer langsung ke

profil tanah. Beberapa praktik yang terintegrasi, seperti

restorasi kualitas tanah dan lansekap, dapat digunakan untuk meningkatkan kapasitas infiltrasi

tanah perkotaan. Sebuah fasilitas infiltrasi dirancang untuk menangkap volume limpasan air

hujan, menahan, dan meresapkan seluruh atau sebagian air tersebut ke dalam tanah.

http://iowacedarbasin.org/runoff/showMan.php?c1=2E-1

What is goal of storm water fee?1. Protect water

supply2. Stream restoration3. BMP-road

construction4. Education for

schools5. Workshops for

better water quality

Infiltrasi air hujan memiliki kelebihan dan kekurangan. Keuntungan dari infiltrasi

mencakup pengendalian kuantitas air dan pengendalian kualitas air.

Kontrol kuantitas air dapat terjadi dengan menangkap dan menahan aliran permukaan dan infiltrasi air ke dalam tanah, mengurangi

volume air yang dibuang langsung ke sungai.

Sistem Infiltrasi dapat dirancang untuk menangkap volume air hujan (volume &

kualitas air) dan meresapkan air ini ke dalam tanah selama beberapa jam atau hari.

Infiltrasi dapat memberikan manfaat sekunder dengan meningkatkan mengisi

ulang akuifer dan meningkatkan aliran dasar sungai di dekatnya.

http://iowacedarbasin.org/runoff/showMan.php?c1=2E-1

What can you do for clean water? 1. Conserve water2. Keep grass

clipping out of stream

3. Keep restaurant and business waste away from rain

Ada beberapa praktik infiltrasi:

1. Parit infiltrasi2. Cekungan infiltrasi 3. Daerah Bioretention (dan taman

hujan)4. Restorasi kualitas tanah asli

lansekap

What can you do for clean water?1. Use min

herbicides/fertilizers & keep off paved surfaces

2. Pick up pet waste3. Report water

pollution

Faktor-faktor yang mengontrol laju infiltrasi dan kapasitas

infiltrasi:

1. Tutupan vegetasi, perkembangan akar, dan kandungan bahan organik

2. Kadar air3. Struktur tanah dan tekstur4. Porositas dan permeabilitas5. Bobot isi Tanah dan

pemadatan6. Slope, posisi landscape, dan

topografi

Rain Garden

Managejemen Air Hujandi Perkotaan

Apa saja yang digunakan untuk mengelola air hujan di perkotaan?

1. Gutters for roof runoff

2. Surface drainage ditches and an underground drainage system.

3. Ditches or tiles direct water to a central basin.

4. Permeable pavement

…http://www.daygroup.co.uk/sustainable-urban-drainage-systems.php

Typical Permeable Pavement Design

Permeable paving in sustainable urban drainage systems (SUDS)

Paving permeabel atau porus dapat digunakan sebagai sarana kontrol limpasan air hujan di jalan-jalan kecil, trotoar, parkir mobil dan taman-

taman kota.

Sarana pengendalian limpasan air hujan di perkotaan adalah sistem drainase perkotaan yang berkelanjutan (SUDS) yang berhubungan

dengan run-off, dan dengan permukaan lahan tempat jatuhnya hujan.

Air hujan melewati permukaan lahan, meresap melalui celah-celah di antara individu paving atau bahan permeabel seperti kerikil atau aspal

porus, menjebak polutan di dalam tanah.

Dalam tanah, bahan polutan akan mengalamu degradasi dan dekomposisi oleh proses alami yang terjadi dalam tanah.

http://www.netregs.org.uk/library_of_topics/water/sustainable_urban_drain_system/permeable_paving_in_suds.aspx

Permeable paving in sustainable urban drainage systems (SUDS)

Dengan menggunakan

permeabel paving dapat dicegah

akumulasi air di permukaan kedap air, menghindari genangan air di tempat parkir.

Sejumlah besar air dapat disimpan dalam tanah di

bawah permukaan.

Hal ini mengurangi kemungkinan

banjir.

http://www.netregs.org.uk/library_of_topics/water/sustainable_urban_drain_system/permeable_paving_in_suds.aspx

Apa saja masalah yang dihadapi?1. Petrochemicals

and metals are washed off with storm runoff water.

2. Rain water and runoff water can dissolve the limestone bedrock.

…http://www.ec.gc.ca/inre-nwri/default.asp?lang=En&n=235D11EB-1&offset=12&toc=show

Linkages between urban runoff and water quality issues.

Dimana lokasinya Rain-garden ?

1. Rain Gardens are near the campus greenhouse (GH)

2. Rain Gardens are near the Horticulture Center (HC)

3. Rain Gardens are in the drainage ditches.

… http://www.architectityourself.com/what-is-a-rain-garden/

Surface Drain system being retrofitted with Rain Gardens (RG)

Green house

Commons-underground drain line

Basin

RG 1 & 2

RG3

…

Runoff from curb cut into Rain Gardens

Alternative ways of dealing with runoff?

1. Direct water to a naturalized setting.

2. Minimize runoff of average rain by 90%, allowing rain garden (plants and soil)

3. Filter pollutants-sediments, dissolved ions- before percolates into groundwater.

Perbaikankualitas air hujan dapat dicapai kalau bahan

polutan tersaring pada saat air hujan merembes melalui

berbagai lapisan tanah.

Ketika air bergerak melalui tanah, partikel dapat diikat oleh partikel tanah. Selain itu, mikroorganisme dalam

tanah dapat mengurangi polutan organik yang

terkandung dalam air hujan.

What is a decentralized runoff management system?1. Runoff water

directed into rain gardens

2. Plant canopy and soil can store excess water.

3. Rain Garden, shallow basin allows runoff water to percolate through the soil and transpire through the plants.

http://rpitt.eng.ua.edu/Class/Computerapplications/Module4/MainCAM4.html…

Urban runoff source areas and drainage alternatives (Pitt 1986).

How does a decentralized system work?

Two ways:1) Plant canopy (trees, shrubs, un-mowed grasses)

A) increase evapo-transpiration B) reduce water percolation.

2) Rain garden soil is a sponge for runoff water

…

Surface Drain system being retrofitted with Rain Gardens (RG)

21

Greenhouse

Commons-underground drain line

Basin

RG 1&2

RG3

…

Rain Garden

Taman hujan dibangun untuk dapat menampung dan segera meresapkan

limpasan air hujan tersebut ke dalam tanah.

Air hujan tidak boleh terlalu menggenang di

taman-hujan, hal ini untuk melindungi

kesehatan tanaman yang tidak tahan genangan air.

Digging out Rain Garden

Spoil piles in background-gravel at entrance Rain Garden

Kalau hujan terjadi di perkotaan yang

permukaannya pedap air, maka diperlukan taman-

hujan yang mampu menampung sebagian limpasan air hujan dan

meresapkannya ke dalam tanah.

Hal ini membantu mengurangi beban debit runoff yang memasuki saluran drainage kota.

Rain Garden

25…http://www.alabamas13.com/story/22110422/with-all-of-this-rain-how-about-a-rain-garden

Taman hujan adalah depresi (cekungan) dangkal yang ditanami dengan tanaman asli yang mengakar kuat

dan/atau rumput. Taman hujan ini lokasinya sedekat mungkin dengan

sumber limpasan air hujan, seperti jalan-jalan kota.

Taman hujan ini akan menangkap limpasan air

hujan dan menahan air ini dan meresapkannya ke

dalam tanah.

Rain Garden

1. Deeper and longer than needed in a residential landscape

2. Why? 3. It had to fit in an

existing drainage ditch surrounded by parking lots.

26…http://soundbook.soundkeeper.org/chapter_ContentID_212_SectionID_7.htm

How to Plan a Rain Garden

1. Garden is down slope from the area it is draining.

2. Small rain gardens are easier to maintain than one large rain garden.

3. Garden should be greater than 10 feet from building foundation.

…http://www.alabamas13.com/story/22110422/with-all-of-this-rain-how-about-a-rain-garden

Building Rain Garden : Placement1. Rain Garden is

on the East side of Horticulture Center.

2. Captures water from the graveled lot on the West side of the Horticulture Center.

…http://rpitt.eng.ua.edu/Class/Computerapplications/Module4/MainCAM4.html

Pollutant deposition and removal at source areas (Pitt 1986).

Other Placement Considerations

• Do not place over a septic system or where water pools more than 5 days.

• The garden soil should drain well.• How a soil drains can be determined by watching

the site after a rainfall event– Does it drain within 2 to 3 day– If not infiltration and percolation rate can be estimated.

• Clay soil or compacted soil can be amended to improve infiltration and percolation.

…

What is water infiltration?1. How quickly

does water move into a soil?

2. Watch a possible area after a rain fall event.

Infiltrasi mungkin tidak cocok untuk di daerah-daerah di mana air-tanah

merupakan sumber utama air minum, karena potensi migrasi kontaminan.

Hal ini terutama berlaku jika air limpasan berasal dari daerah

komersial atau industri, di mana mungkin ada kontaminasi limbah

organik atau logam.

What is the percolation rate?

• The percolation rate is the time it takes for one inch of water to pass through a soil.

• The ABAS class used these perc rates:<60 minutes/inch60-75 minutes/inch>75 minutes/inch

• A good rate for a rain garden is <60 minutes per inch.

…

How to determine percolation rate by soil texture? • Using a post hole

digger, dug holes 6 to 8 inches for a shallow basin or 24 to 36 inches for a deep basin.

• For faster than 60 minutes per inch– Excavate soil has a

medium or fine textures subsoil

– Or fine reddish textured subsoil

… http://lowerseletarlearningtrail-2g.blogspot.com/2012/04/abc-learning-trail-lower-seletar.html

How to determine percolation rate by soil texture?

• For 60 to 75 minutes per hour– Excavated soil is reddish fine textured subsoil to

at least 24 inches and yellow clay between 24 to 36

• For slower than 75 minutes per inch – Excavate soil with bed rock within 36 inches – or soil having a yellowish, grayish, or blackish

fine textured subsoil

…

Uji Rasa untuk Tekstur Tanah

1. Fine texture soils: Sandy clay, Silty clay and clay

2. Medium texture soils: silt loam, loam, sandy clay loam, clay loam, silty clay loam

… http://conservationdistrict.org/2012/new-rain-garden-fact-sheet-available.html

35

Rain Garden: Ruang sempit

… http://www.urbangardensweb.com/2010/01/29/rain-gardens-for-small-urban-spaces/

Air hujan mencuci polutan di sepanjang jalan dan memasuki

taman-hujan

Air hujan menyebar ke seluruh permukaan taman-hujan dan

vegetasi menangkap sedimen kasar

Air hujan yang bersih dikumpulkan dalam pipa dan disalurkan ke perairan bebas

Air hujan meresap ke bawah melalui

massa tanah, sedimen halus

dan polutan ditangkap oleh

tanah

Building Rain Garden : Laju Perkolasi

1. Dug holes to 24 inches, excavated soil in the proposed Rain Garden, was medium textured.

2. 1” gravel in bottom, filled holes with 6” of water and record time to drop one inch. Stuck a tooth pick in the side of the hole for measuring water drop.

3. Measured, 15 minutes per ¼” water drop, or 60 minutes per 1” water.

… http://thedoodlehouse.com/2012/02/28/crushing-on-rain-gardens/

Building Rain Garden: Sizing?

• The size of the rain garden can be calculated.– Residential size: 100 to 300 sq ft

• The size required to capture surface runoff around the site was determined by observations.– E.g. Dimensions: 8 feet x 24 feet by 6 inches deep

…

Finding the Area Rain Garden

1. If rain garden catch water from a rain spout, use that part of the roof area.

2. Lawns, graveled or paved driveways, additional runoff water for a rain garden.

3. The area to be drained can be multiplied by a size factor to determine area of rain garden.

…

Size factors are determined according to the type of soil and the depth of the garden and differ if the garden is <30’ or >30’ from a building

<30Feet

3-5” deep

6-7” deep

8” deep

Sandy Soil

0.19 0.15 0.08

Silty Soil

0.34 0.25 0.16

Clayey Soil

0.43 0.32 0.20

>30 feet For all depths

Sandy Soil 0.03

Silty Soil 0.06

Clayey Soil 0.10

% Slope Relates to the Depth of the Rain Garden

1. For slopes <4%, the garden depth should be 3-5 inches deep.

2. Between 5-7%: 6 to 7 inches deep3. Between 8-12%: about 8 inches deep4. For slopes over 12%, a rain garden will take

a great deal of fill, another location should be considered.

…

Calculating the Slope & Area of the Rain Garden

1. Drive two stakes about fifteen feet from each other (one uphill, one downhill).

2. Tie a string level to each stake and adjust it to make it level.

3. Measure height difference between the ground and the string in feet, divide difference by the distance between the two stakes.

4. Multiply by 100 to get the percent slope.

…

Defining the Shape of the Rain Garden

1. Shape should be aesthetic. 2. Recommend, length of the garden be

perpendicular to the slope, will catch as much water as possible.

3. Garden should be twice as long as it is wide.4. Width should be no more than 10-15 feet.

…

Building Rain Garden: Digging

1. Mark the perimeter of the garden.2. Front end loader was initially used; for residential

garden use a garden tiller .3. District conservationist showed the class how to

measure slope with a laser level. It is easy to do with a string and line level.

4. The inlet was higher than the outlet and the bottom of the garden was leveled.

…

Digging a Rain Garden

1. Hammered stakes around the perimeter and ran string level between stakes across the middle of the garden.

2. Dig the bed level at the desired depth with rakes and shovels.

3. Use the removed soil to build a berm on the downhill edge of the garden.

4. Covered channel above and below inlet and outlet with landscape fabric and gravel

…

Building Rain Garden : Planting

1. The Soil Analysis class planted native bushes and perennials.

2. The arrangement was done in a naturalistic fashion using odd number groups.

3. Odd number groups ease future maintenance of the Rain Garden.

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Planting a Rain Garden

1. Rain garden plants should be tolerant of moist and dry conditions.

2. Commercial landscape plants can be used but consider native plants.

3. Plant density should be higher and more naturalistic looking than commercial type plantings.

…

Building Rain Garden : Mulch and Rock

1. Placed landscape fabric at the entrance of the Rain Garden.

2. Covered the bottom of the Rain Garden with double-shredded mulch to the desired depth.

3. Covered the landscape fabric at the entrance with river rock.

…

Rain Garden

Sebuah taman hujan dengan

vegetasi di daerah perkotaan

dapat memperbaiki

kualitas air dan kenyamanan lingkungan sekitarnya.

Rain Garden - Specs• Infiltration Rate

– 3 inches in 90 minutes• Depth

– 7 inches• Materials Used

– river rock, landscape fabric, recycled concrete (from construction site on campus), native plants.

…

Plants Used1. River Oats - Chasmanthium latifolium2. Swamp Milkweed – Ascelpias incrnata3. Red Twig Dogwood - Cornus sericea4. False Sunflower – Heliopsis helianthoides5. Helberd Leaf Rose Mallow – Hibiscus laevis6. Inkberry Holly – Ilex glabra7. Winterberry Holly – Ilex verticillata8. Big Blue Lobelia – Lobelia siphilitica9. Common Rush - Juncus effusus

Construction of Rain Garden - after Excavation

Tanah di taman hujan harus longgar dan porous, sehingga

kemungkinan tanah perlu diplah sebelum

penanaman tanaman.

Penambahan Kompos organik, pasir,

vermiculite, dan material tanah liat ke tanah

aslinya dapat memperbaiki kualitas tanah di taman-hujan.

Landscape Fabric

Although fabric is

beneficial to prevent

weeds, it does not allow the

rock to settle.

Notice how the fabric and rock washed away due to heavy rain.

Landscape Fabric Correction

We corrected the problem

with recycled concrete and rocks to hold the fabric in place and to

slow down the water flow.

Rain Garden: lime dust on river rock

…

Agar supaya taman-hujan dapat bekerja dnegan

sebaik-baiknya, lokasinya harus di tempat dimana

limpasan air hujan mengumpul, atau saluran

air drainage. Untuk memilih tempat

terbaik (jika ada pilihan), diperlukan pengamatan lapangan setelah hujan

lebat.

In Summary

1. Environmental problems caused by surface drainage in developed areas can be reduced by changing landscape practices.

2. Limit mowed lawn space and raise mower blade to increases plant canopy.

3. Stacked Rain gardens in the landscape allow excess water to infiltrate the soil in many places before water flows to lowest elevation.

…

Plant Lists

Plant lists will be available on request from:1. your local extension office 2. Tennessee Master Gardeners3. web search: rain garden plants

…

Rain Garden

Vegetasi di taman-hujan harus dapat beradaptasi

dengan kondisi tanah basah dan tanah kering.

Tanaman asli biasanya sangat cocok untuk taman-

hujan, karena mereka mampu beradaptasi

terhadap kondisi lokal. Tanaman yang cocok untuk taman-hujan akan bervariasi

dari satu daerah dengan daerah lainnya.

Entrance to Rain Garden

…

Taman hujan dengan tanaman asli, di kawasan permukiman, dapat

mengurangi jumlah polutan yang memasuki badan air terdekat atau

saluran drainage kota.

Taman hujan juga dapat mencegah erosi permukaan, dapat mengurangi

genangan air, dan menciptakan habitat bagi satwa liar, seperti

burung.

Taman hujan dapat diintegrasikan dnegan Ruang Terbuka Hijau Kota

.

Rain Garden

…http://www.alabamas13.com/story/22110422/with-all-of-this-rain-how-about-a-rain-garden

Ada banyak pohon-pohon dan semak-semak yang cocok untuk taman-hujan, namun sebagian besar tumbuhan ini ukurannya

terlalu besar untuk menjadi bagian dari sebuah taman-hujan

yang kecil.

Dengan tanaman yang lebih kecil, dan media tanah yang bagus, taman-hujan kecil di

ruang perkotaan dapat menjadi sarana keindahan kota dan

kenyamanan ekologis lingkungan kota.

Fact sheet- Rain Garden Design(2)

Who Should Create a Rain Garden?1. Suitable any land use; Residential, commercial,

industrial2. Place so impervious surfaces drain into depression3. Grass buffer strip4. Slows water entering rain garden; Surface filters

particulates from runoff5. Pond area6. Depression area, stores water; Evaporation;

Particulate not filtered to settle to bottom; 7. 6 inch depth; Not pond more than 3-4 days – avoid

mosquito breeding

Fact sheet- Rain Garden Design(4)

Components of a rain garden1. Mulch/Organic Layer2. Decomposed organic material; Removes metals; Shredded

hardwood mulch3. Planting Soil4. Leaf mulch (20%), sandy soil (50%) and 30% top soil; Clay

particles adsorb5. Planting Selection 6. Species that tolerate extremes, perennials7. Site Considerations8. Site: Intercept water runoff9. Bioretention area: 5 to 7% of drainage area (example ¼ roof

area)