Landslide Prevention Project in Thailand

Landslide
Prevention Project
in Thailand
23 th June,
2011
Landslide and Surface Erosion

OUTLINE
• Landslide in Thailand
- Type of Landslide
- Past event
• Landslide Susceptibility Map
• Landslide Prevention Project
- Soil and Water Conservation
measures

Landslide in Thailand-Type of Landslide
- Debris avalanche ,Rotational Slide ,Surface Landslides
or Shallow Landslides
- Heavy rain and continued for a long time in the
mountains
- usually occurred in exiting water channel and small
ditches in hillside
- slope over 30% , depth soil horizon

- Soil and rock become wet can not be settled on.
- the mass flow of sediment, soil and rock mixed with
the mud flowing down the slope to the surface at low
speeds , down with sand and gravel along the way
then increase velocity and high speed become more
powerful as the "Debris flow"

ตค. 45
อ.แมสะเรียง แมฮองสอน
พค. 47
อ.สบเมย แมฮองสอน
กย. 47
อ.เมืองแมฮองสอน
กย. 47
อ.แมสะเรียง แมฮองสอน
กย. 48
อ.ปางมะผา แมฮองสอน
Major Land Slide Events
from 1970 - 2011
.
พค. 47
อ.อมกอย เชียงใหม
พค., กย. 47
อ.แมแจม เชียงใหม
กย. 47
อ.ฝาง เชียงใหม
พค 49 สุโขทัย
กค.,กย. 47
อ.แมอาย เชียงใหม
กย. 45
อ.แมแจม เชียงหม
กย. 51อ . ทาวังผา นาน
พค. 49
อ.ลับแล, อุตรดิถย
พค.47
อ.แมระมาด อ,แมตื่น ตาก
พค. 44
อ.วังชิ้น แพร
พค. 49 แพร
กย.47
อ.ลอง แพร
พย. 13
อ.ทับสะแก
ประจวบคีรีขันธ
มีค. 54
อ.เขาพนม กระบี่
ตค. 47
อ.เมือง กระบี่
ตค. 44
อ.กะทู จ.ภูเก็ต
ธค. 25
อ.ศรีบรรพต พัทลุง
มีค 54
อ.กาญจนดิษฐ สุราษฎรธานี
มค 18
อ.รอนพิบูลย นครศรีธรรมราช
พย. 31
อ.พิปูน อ.ลานสกา นครศรีธรรมราช
มีค. 54
อ.นบพิตํา อ.สิชล นครศรีธรรมราช
พค 47
อ.ธารโต จ.ยะลา
ธค. 48
อ.บันนังสตาร ยะลา
กย. 43
อ.หลมสัก, อ.เมือง เพชรบูรณ
สค. 44
อ.หลมสัก เพชรูรณ
สค. 42,44
อ.เขาคิชกูฏ จันทรบุรี
No. of Land Slide

1988 , Debris avalanche occurred in Ka Thoon watershed,
Ka Thoon sub-district, Phiboon district, Nakhon Si
Thammarat province.

Sediment deposit cover risk area ~ 3 m. height

1999, heavy rain hit the area in Khitchakut
district,
Chanthaburi Province

2001, landslide occurred in Soi sub-district,
Wang Chin district,
Phrae Province

2001, Debris flow occurred Lomsak
district,
Petchabun province

village affected at downstream

Mae Jam Basin, Chiang Mai
(2003)

2005, Shallow landslide with debris flow,
Pangmapha district , Maehongson province

2006, Shallow landslide with debris flow
occurred in Uttradit province,

2009, Ban Namka, Pha-changnoi subdistrict,
Phong district ,Phayao Province

2009, Sediment deposit cover farmland,
Ban Namka,Pha-changnoi subdistrict,
Phong district , Phayao Province

March 2011, debris avalanche
occurred, Ban Pean,
Thepprarat subdistrict, Sichon district ,
Nakhon Si Thammarat province

March 2011, debris avalanche
occurred, Ban Tonharn,
Kaopanom district, Krabi province

Landslide
Susceptibility
Map
Province
Legend
Stream
Susceptibility level
Low
Moderate
High
Landslide susceptibility area
covers 56 provinces, 196,800 km 2
Village at risk of Landslide
1,007 villages

Soil and water conservation project
in the landslide risk areas.
Soil and water conservation measures to protect and
restore areas of potential landslide in the area of
landslide susceptibility- moderate to high level
soil and water conservation measures
1. Hillside ditches
2. Check dam
3. Waterways
4. Sediment trap
5. Vetiver
6. Tree planting
– Rubber, Bamboo, Teak

conservation structure
1. Hillside ditches
- type 5, slope 15-35%

conservation structure
1. Hillside ditches
-type 6,
slope > 35%

conservation structure
2. Check dam
Masonry
check dam
Bamboo
barrier

Sacks of cement

conservation structure
3. Waterways, diversion dicth

conservation structure
4. Sediment trap
Sacks of cement

Vegetative conservation
measures
5. Vetiver

Vegetative conservation
measures
6. Tree , Orchard planting
– Rubber, Bamboo, Teak, Coffee etc.

???those method appropriate to prevent
landslide and severe erosion??? (Q.#1)
Are there another measure can implement in
upland agriculture? (Q.#2)
Is there only soil and water conservation
measures can protect the land from
landslide? (Q.#3)
Are there another method can integrated
with soil and water conservation measure
,especially in upland farming? (Q.#4)

Question 1:Are those measures applied
currently by LDD Thailand enough to prevent
landslides and severe erosion?
• Land Use Activities:Agriculture
• The conversion of undisturbed land to agricultural
production has often disrupted the previously
existing state of dynamic equilibrium.

• Introduced at the landscape, watershed, stream
corridor, stream, and reach scales, agricultural
activities have generally resulted in encroachment
on stream corridors with significant changes to the
structure and mix of functions usually found in
stable systems.

• Vegetative Clearing
• One of the most obvious disturbances from agriculture
involves the removal of native, riparian, and upland
vegetation. Producers often crop as much productive land
as possible to enhance economic returns; therefore,
vegetation is sacrificed to increase arable acres.
• Vegetative removal from streambanks, floodplains, and
uplands often conflicts with the hydrologic and geomorphic
functions of stream corridors.
• These disturbances can result in sheet and rill as well as
gully erosion, reduced infiltration, increased upland surface
runoff and transport of contaminants, increased
streambank erosion, and unstable stream channels.

Soil Exposure and Compaction
• Tillage and soil compaction interfere with soil’s capacity to
partition and regulate the flow of water in the landscape,
increase surface runoff, and decrease the water-holding
capacity of soils.
• Increases in the rate and volume of throughflow in the
upper soil layers are frequent. Tillage also often aids in the
development of a hard pan, a layer of increased soil
density and decreased permeability that restricts the
movement of water into the subsurface.
• The resulting changes in surface and ground water flow
often initiate incised channels and effects similar to those
discussed previously for instream modifications.

Sediment and Contaminants
• Disturbance of soil associated with agriculture
generates runoff polluted with sediment, a major
nonpoint source pollutant.
• Pesticides and nutrients (mainly nitrogen,
phosphorous, and potassium) applied during the
growing season can leach into ground water or
flow in surface water to stream corridors, either
dissolved or adsorbed to soil particles.
•

• Soil salinity is a naturally occurring phenomenon found
most often in floodplains and other low-lying areas of wet
soils, lakes, or shallow water tables.
• Dissolved salts in surface and ground water entering these
areas become concentrated in the shallow ground water
and the soils as evapotranspiration removes water.
Agricultural activities in such landscapes can increase the
rate of soil salinization by changing vegetation patterns or
by applying irrigation water without adequate drainage.
• In the arid and semiarid areas, irrigation can import salts
into a drainage basin. Since crops do not use up the
salts,they accumulate in the soil. Salinity levels greater
than 4 millimhos/cm can alter soil structure, promote
waterlogging, cause salt toxicity in plants, and decrease
the ability of plants to take up water.

Forestry
• Three general activities associated with forestry
operations can affect streamcorridors.
• 1. tree removal,
• 2. activities necessary to transport the harvested
timber,
• 3. preparation of the harvest site for regeneration.

Removal of Trees
• Forest thinning includes the removal of either
mature trees or immature trees to provide more
growth capability for the remaining trees.
• Final harvest removes mature trees, either
singularly or in groups. Both activities reduce
vegetative cover.

• Tree removal decreases the quantity of nutrients in the
watershed since approximately one-half of the nutrients in
trees are in the trunks.
• Instream nutrient levels can increase if large limbs fall into
streams during harvesting and decompose. Conversely,
when tree cover is removed, there is a short-term increase
in nutrient release followed by long-term reduction in
nutrient levels.
• Removal of trees can affect the quality, quantity, and timing
of stream flows for the same reasons that vegetative
clearing for agriculture does. If trees are removed from a
large portion of a watershed, flow quantity can increase
accordingly.
• The overall effect depends on the quantity of trees
removed and their proximity to the stream corridor.

• Increases in flood peaks can occur if vegetation in the area
closest to the stream is removed. Long-term loss of
riparian vegetation can result in bank erosion and channel
widening, increasing the width/depth ratio. Water
temperature can increase during summer and decrease in
winter by removal of shade trees in riparian areas.
• Allowing large limbs to fall into a stream and divert stream
flow may alter flow patterns and cause bank or bed erosion
• .
• Removal of trees can reduce availability of cavities for
wildlife use and otherwise alter biological systems,
particularly if a large percentage of the tree cover is
removed. Loss of habitat for fish, invertebrates, aquatic
mammals, amphibians, birds, and reptiles can occur.

Transportation of Products
• Forest roads are constructed to move loaded logs from the
landing to higher quality roads and then to a manufacturing
facility. Stream crossings are necessary along most forest
road systems and are especially sensitive areas.
• Removal of topsoil, soil compaction, and disturbance by
equipment can result in long-term loss of productivity,
decreased porosity, decreased soil infiltration, and
increased runoff and erosion. Spills of petroleum products
can contaminate soils.
•
• Trails, roads, and landings can intercept ground water flow
and cause it to become surface runoff.

Site Preparation
• Preparing the harvested area for the next generation of
desired trees typically includes some use of prescribed fire
or other methods to prepare a seed bed and reduce
competition from unwanted species. Mechanical methods
that completely remove competing species can cause
severe compaction, particularly in wetsoils.
•
• This compaction reduces infiltration and increases runoff
and erosion. Moving logging debris into piles or windrows
can remove important nutrients from the soil.
• Depending on the methods used, significant soil can be
removed from the site and stacked with piled debris, further
reducing site productivity.

• Intense prescribed fire can volatilize important nutrients,
while less intense fire can mobilize nutrients for rapid plant
uptake and growth. Use of fire can also release nutrients to
the stream in unacceptable quantities.
• Mechanical methods that cause significant compaction or
decrease infiltration can increase runoff and therefore the
amount of water entering the stream system. Severe
mechanical disturbance can result in significant erosion
and sedimentation.
• Conversely,less disruptive mechanical means can
increase organic matter in the soil surface and increase
infiltration. Each method has advantages and
disadvantages.

Soil and water conservation project
in the landslide risk areas.
Soil and water conservation measures to protect and
restore areas of potential landslide in the area of
landslide susceptibility- moderate to high level
soil and water conservation measures
1. Hillside ditches
2. Check dam
3. Waterways
4. Sediment trap
5. Vetiver
6. Tree planting
– Rubber, Bamboo, Teak

Question 2:Are there other measures can
be implemented in upland agriculture?

Question 3:Is there only soil and water
conservation measure can protect the land
from landslide?

Soil Conservation Design Guidelines for Watershed Management
Steep terrace works with Stonewalls
and Vetiver grasses +native tree
reforestation
Simple terrace works with Vetiver grasses
+Natural succession
Monkey cheek
Hillside drainage channels
Monkey cheek
Channel diversion with buffer grass strips
along stream banks
Reforestation
area or permanent
fruit trees
Permanent fruit trees
Road access
Foothill rehabilitation with
fast growing trees
Land-use Design for Rehabilitating
Landslide Area (after)

Question 4: Are there measures can be
integrated with soil and water conservation
measure,especially in upland farming?

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源 汙 染 維 害 野 溪 。

農 地 的 最 佳 管 理 方 案
- 應 用 及 其 成 效
• 應 用 及 其 成 效
1. 農 地 利 用 可 能 衝 擊 濱 溪 廊 道 的 環 境 。
2. 當 執 行 集 水 區 管 理 規 劃 以 改 善 環 境 時 。
3. 應 結 合 集 水 區 管 理 規 劃 , 農 地 管 理 計 畫 及 河 川
廊 道 復 育 計 畫 。

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- 應 用 及 其 成 效
• 應 用 及 其 成 效
4. 應 考 量 四 季 變 化 的 水 , 土 , 微 生 物 等 資 源 。
5. 耕 作 等 農 業 行 為 應 考 量 相 鄰 土 地 的 環 境 品 質 。

農 地 的 最 佳 管 理 方 案
- 應 用 及 其 成 效

森 林 地 的 最 佳 管 理
方 案

森 林 地 的 最 佳 管 理 方 案
- 應 用 及 其 成 效

都 市 開 發 地 的 最 佳 管 理 方
案
• 個 別 或 系 統 的 處 理
設 計 來 減 輕 , 移 除
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於 受 開 發 行 為 及 各
式 活 動 造 成 影 響 。

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- 應 用 及 其 成 效
• 應 用 及 其 成 效
1. 用 來 改 善 或 恢 復 受 影 響 的 自 然 生 態 的 功 能 。
2. 整 體 濱 溪 廊 道 需 一 併 考 量 各 河 段 的 最 佳 管 理 方
案 。
3. 個 別 都 市 化 的 管 理 方 案 應 配 合 整 體 河 道 復 育 方
案 辦 理 。

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- 應 用 及 其 成 效
• 應 用 及 其 成 效
4. 都 市 化 會 造 成 很 大 的 影 響 且 具 複 雜 性 。
5. 可 行 方 案 包 括 .. 滯 洪 設 施 , 池 塘 , 人 造 濕 地 ,
油 水 分 離 設 施 , 植 生 窪 地 , 過 濾 帶 , 入 滲 池 ,
透 水 舖 面 , 市 區 內 的 造 林 等 。

Thank
you