Disaster mitigation - land slide

DISASTER MITIGATION

LANDSLIDES

SUBMITTED BY – JANUMI RATHOD PARTH SADARIA

MASTERS OF URBAN AND REGIONAL PLANNINGDepartment of Architecture,

Faculty of Technology & EngineeringThe Maharaja Sayajirao University of Baroda,

Vadodara, IndiaSEPTEMBER 2015

Understanding DisasterCRED (The Centre for Research on the Epidemiology of Disasters)

“A situation or event which overwhelms local capacity, necessitating a request to a national or international level for external assistance; an unforeseen and often sudden event that causes great damage, destruction and human suffering.”

International Federation of Red Cross and Red Crescent Societies

A disaster occurs when a hazard impacts on vulnerable people. (VULNERABILITY+ HAZARD ) / CAPACITY = DISASTER

Natural Disasters – Categories, Types

Mass Movements - Mass movements are massive failures of slope masses including rock, debris, soils and snow/ice that cause loss of life, economy, environment, land and natural resources, the main reason being gravity.

TYPES Rock fall Landslide Avalanche Subsidence

AGENTS/TRIGGERS – wind, air, water

MOVEMENT – Slide, Flow, Rotate, Fall

MATERIALS – Rock, Debris, earth

Characteristics landslide landforms

Soil and rock fragments slide down the slope

The wet ground breaks up and falls down the hillside

Rotational slide of loose materials or rock fragment

The falling of a newly detached mass of rock from a cliff or down a very steep slope.

Source - British Geological Survey and Eastern Illinois University

Causes

Man- made Causes

•Excavation (particularly at the toe of slope)

•Loading of slope crest

•Draw -down (of reservoir)

•Deforestation

•Irrigation

•Mining

•Artificial vibrations

•Water impoundment and leakage from utilities

Physical Causes

•Prolonged precipitation

•Rapid draw- down

•Earthquake

•Volcanic eruption

•Thawing

•Shrink and swell

•Artesian pressure

Morphological Causes

•Ground uplift (volcanic, tectonic etc)

•Erosion (wind, water)

•Scour Deposition loading in the slope crest

•Vegetation removal (by forest fire, drought etc)

Source - American Geophysical Union, Nick Rosser

Landslide Fatalities, 2007

Existing large dams UN large dam database (2012)

• Each red dot is a large dam on the database• Existing dams are concentrated in mountainous areas, but not in very high mountains

Source - Dave Petley, American Geophysical Union, Vajont Conference, 2013

Large dam density UN large dam database (2012)

• Contour map of the density of existing large dams


Large dams and fatality-inducing landslide events (2004-2011)

• The distribution of fatal landslides and large existing dams does not overlap, specifically in the Himalayas


Distribution of landslides associated with large dams

• Each dot is a landslide associated with a large dams in the period 2003-2012• NOTE- Almost all are in Asia, Hotspots are in Himalayas and China


Proposed dams and dam related landslides in Himalayan region

• Dam: planned or under construction• Fatal landslide associated with a dam


Scenario

• Landslides rank third in terms of number of deaths due to natural disasters.

• Himalayan Landslides kill 1 person / 100 Km² / yr.

• Estimated average losses due to landslides in Himalaya costs > Rs. 550 crores / yr. & > 200 deaths.

• The hazard affects over 0.49 million km², over 15 % of our country's area

Top countries affected by landslides

Scenario

Case study - Malin landslide-Pune – 30th July, 2014, 0300 hours

Major causes (Geological Survey of India study) -

Immediate trigger – Intense rainfall - 10.8 cm (4 in) of rain on 29

July and continuing the next dayLong term –

Agricultural practice –paddy cultivation, which required levelling of steep areas in the upslope, which contributed to instability

Deforestation Large scale land use modifications Construction activities – stone quarrying, etc. 1.5 km from Dimbhe dam

Causalities – more than 160 deaths

• Malin village, Ambegaon Taluka, 110 km from Pune, West Maharashtra,

Malin receives very heavy rainfall on the 29th July, 9 pm by NASA TRMM

Malin receiving high rainfall on the 30th July 2014, 9 pm IST NASA TRMM

Rainfall

Mass movement events in the Himalaya: The impact of landslides on Ladakh, India.

Case – Landslide Hazard Mitigation in Nilgiris district, Tamil Nadu• Severe to very high landslide hazard prone area - (Building Materials and Technology Promotion Council (BMTPC), Government of India

• GSI and State Geology Branch of Government of Tamil Nadu studied 300 landslides from 1978-1979 in the densely populated and developed area of 200 sq.km between Ooty and Coonoor.

• OUTCOMES – a. The main causes of landslides b. The role played by excessive deforestation, obstruction to the normal

drainage channels and changes in land use were studies by the team.

From 10th to 15th November, 2009

Landslides/Landslips Lives lost Damage

1150 803785 huts damaged, parts

of railway and road line damaged

Case – Landslide Hazard Mitigation in Nilgiris district, Tamil Nadu

Issues identified by the study –• The possibility of occurrence of

landslide will increase from 70% to 100% in the Next 10 – 20 years

• Urban areas where buildings are constructed on or close to landslide

• Improper drainage system• Lack of awareness• No early warning system

Recommendations –• Avoid further development in high-risk landslide

prone areas, limit existing-use rights to rebuild, and limit the use of buildings

• As suggested by National Disaster Management Authority (NDMA), Government of India in the National Disaster Management Guidelines for landslides, from the funds available with the District Planning and development Council in landslide prone areas, a part will be allocated for the implementation of landslide management schemes in the Nilgiri district.

• Landslide Hazard Mitigation Through Cost Effective Technology – Soil bio-engineering

Soil bio-engineering - the use of plant material, living or dead, as building material to reduce environmental problems such as shallow, rapid landslides and eroding slopes and stream banks

Preventive Engineering Measures• The main factors which contribute to landslides are Slope, water content, geological

structure, unconsolidated or loose sediments, lithology and human interference.

a) Slope: Retaining wall may be constructed against the slopes, which can prevents rolling down of material. Terracing of the slope is an effective measure.

b) Effect of water: Make proper drainage network for quick removal of percolating moisture or rain water by constructing ditches and water ways along the slope

c) Geological structures: Weak planes or zones may covered or grouted to prevent percolation of water, this increases the compaction of loose material.

Source – International Council For Science, Science Plan for Hazards and disasters

NATIONAL DISASTER MANAGEMENT GUIDELINES, MANAGEMENT OF LANDSLIDES AND SNOW AVALANCHES,

GOVERNMENT OF INDIA

Mission - To minimise the impact of landslides and snow avalanches on life, property and economic activity

The following nine major areas have been identified for systematic and coordinated management of landslide hazards:

• Landslide hazard, vulnerability, and risk assessment. • Multi-hazard conceptualisation. • Landslide remediation practice. • Research and development; monitoring and early warning. • Knowledge network and management. • Capacity building and training. • Public awareness and education. • Emergency preparedness and response.• Regulation and enforcement.

1. Preparation of landslide hazard zonation maps

2. Plan/induce settlements such that they do not fall under the path of risk

3. General Development Control Regulations (GDCR) to be formulated keeping in mind the location and context of place and have to include no development zones or risk zones

4. Prepare monitoring and early warning systems

5. Create preparedness (landslide event, medical) by awareness in the locality

6. Consider role of private and corporate sector in post-disaster situation

Mitigation Measures

7. Construct suitable engineering slope stabilizing mechanisms along with cost-effectiveness

o Geometric – changing geometry of slopeo hydrological – attempt to reduce ground water

level or reduce water contento Mechanical – increase strength by active (e.g.

anchors, rock or ground nailing) or passive external forces (e.g. structural wells, piles or reinforced ground)

8. Suitable site selection for urban planning components like housing, infrastructure, etc in hilly areas

9. Adopt landslide safe land use practices 10. Update and revise Model Town Planning

and Land Use ByeLaws

Mitigation Preparedness

ResponseRecovery

Landslide Hazard Zonation Map

1. Parameters for Slope Instability

1.Lithology 2.Structure 3.Slope Morphology 4.Relative Relief 5.Land Cover 6.Land Use 7.Hydrological Conditions 8.Slope Erosion 9.Rainfall 10.Landslide Activity 11.Material / Overburden Properties 12.Seismicity

2. Finally, prepare Landslide Hazard Management Plan and hence publish Landslide Atlas

3. Example of a corridor in Himachal Pradesh -

Source - Defence Terrain Research Laboratory



References• Landslide Mapping and Vulnerability Assessment, Defence Terrain Research

Laboratory • International Journal of Environmental Science and Development, Vol. 3, No. 5,

October 2012, G. P. Ganapathy and C. L. Hada, Landslide Hazard Mitigation in the Nilgiris District, India–Environmental and Societal Issues

• Dave Petley, American Geophysical Union, Vajont Conference, 2013• www.agritech.tnau.ac.in/agriculture/agri_majorareas_disastermgt_landslide.html• www.portal.gsi.gov.in/portal/page?

_pageid=127,671647&_dad=portal&_schema=PORTAL&1200• www.prezi.com/agxieocrjbr4/mass-movement-management-case-studies-

definitions• www.dnaindia.com• www.sandrp.wordpress.com

Thank you

Education

Disaster mitigation - land slide