Contemporary issues: Landslides and Floods

Topic                                          landslide and floods 

                                     GS 3 mains       Geography of India

 Landslides 

Landslides occur mainly in Himalayan regions, western ghats, and in the Nilgiris.

Causes of landslides in the western ghats: According to geologists western ghats witnessed because of various causes at Raigad, Ratnnagiri, satara district at Maharashtra, Nilgiri Kerala. 

Note-Indian Institute on geomagnetism, an autonomous research institute under the department of science & technology, government of India, has studied parts of western ghats and identified landslides susceptible villages in Ahmednagar district Maharashtra. 

• Anthropogenic activities: anthropogenic activities have given rise to anomalous slopes and due to gravitational pull and rain, the overlying material comes down.   In western ghats, if you have continuous rainfall for a couple of days, the soil gets soggy, leading to landslides. Activities such as 
• Human settlement 
• Haphazard cutting of mountain slopes for road construction, highways, railways
• Fluctuation in vegetation loosening the soil layer 
• Deforestation 
• Unchecked mining 
• Concentration of extremely heavy rain at particular spot
• Change in vegetation also leads to landslides 
• The windmill project that have come up on the ghats have caused huge fractures on the mountain loosening structures. 
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• Measures : western ghats Ecology experts panel in 2010-11 recommendations are:
• To stop Haphazard road construction 
• To stop illegal mining 
• Activities should not be carried out in Ecological sensitive zones.
• To stop Haphazard planning of highway by cutting mountains slopes.
• To check construction and mining activities. 
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• Causes of landslides in the Himalayan region
• The incident of landslides in the Himalayan regions occur because of movement of tectonic plate. 
• The Himalyas is the youngest mountain ranges and still rising. Strata are fragile. It is prone to landslides, erosion, creeping and sinking. 
• The sediments are not yet compacted; they are loose.
• There is a tectonic activity with the plate moving up which causes instability.
• It does not require any precipitation activity, landslides occur in dry season there.
• Impact of landslides 
• Loss of lives 
• Damage of houses
• Leads to human displacement 
• Falling of trees 
• Vegetation loss 
• Damage of constructed roads, highway and rail lines. 
• Blockade of roads 
• Trekkers deaths 
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Landslides in kerala : 

the most worst hit/affected district is Idduki and Koyattam.

• Causes: 
• Heavy rains downpour and created havoc in the state gushing water and Boulder coming down from the nearby hills.
• Alert 
• Yellow alert: it indicates severely bad weather that could change for the worse and cause disruptions in day to day activities 
• Pamba rivers: 
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• Located in Pathanamthitta district. 
• Mouth of the river is vembanad lake.
• Western ghat river flowing to the west towards Arabian sea.
• it is the third longest river in the kerala state after the Periyar and pharattappuzuha rivers. 
• It is also known as "Dakshina Bhagirathi"
• In ancient time it was called "River Baris"
• On the bank of Pamba River Sabarimala temple, changanoor Mahadeva Temple Adoor Mannar Temple, Thiruvalla sreevalabhapuram temple are present. 
• Sabarimala temple: it is dedicated to the lord Ayappa ( Sri Dharmasasta), appeared to the Pandalam Raja as child on the  south bank of Pamba River at Sabarimala hills. 
• Pamba river is venerated as Ganga of kerala and devotees of lord Ayappa believe the emerging oneself in the pamba is equivalent to bathing in the Holy Ganga river. 
• Bathing in river, believed to absolve ones' sins.
• Kakki dam is on river Kaki a tributary of Pamba river.
• Sholapur dam
• Pampa reservoir
• Idamalayar reservoir
• Idduki reservoir of Cheruthoni dam

Landslides in Nainital 

Nainital has been frequently witnessing Landslides especially during monsoon and endangered life . Nainital falls in zone IV of earthquake Zoning map of India. 

Measures: 

• Planning and design of surface drainage networks 
• Construction of retaining walls with inclined perforated pipes 
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Floods 

Causes if Flooding 

• Overflowing of rivers 
• Lack of drainage system 
• Concretization 
• Heavy incessant rainfall 

Losses:

• Rain related deaths 
• Roads blocking due to landslides 
• Washed away of town 
• Damage of shunting line of railway station 
• Roads damaging 
• Damaged of bridges 
• loss of crops such as paddy
• Collapse of building, institutions, polls etc.
• Loss of industrial production due to flooding in industrial areas 

Disasters management 

1. Army and Indian Air force are assisting agencies  state disasters response force ( (SDRF) to  rescue the stranded people. Airforce has taken choppers to rescue the people. 
2. Hospital treatment 
3. Resque operation by the SDRF and ITBP

Keywords: 

Uttarakhand floods 

• Flash flood means sudden flood, triggered by the cloud burst at Ramgarh in Uttarakhand Nainital district in October 2021. Kosi river over flowing and flood occurred in Ramgarh. Water from Nanital lake over flowed on to mall road and entered the Naina Devi temple, 
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• Incessant rain means continuous rainfall 
• Cloud burst means extremely sever and sudden heavy localized rainfall leading   flash flooding, landslides, subsidence of lands;
• Torrential rainfall leading to water logging logging 
• Debris broken rock material with soils and water or without water.
• Water level means height/depth of water in water bodies such river 
• Landslides means slide down of Debris over its weak surface 
• River Bank 

Floods affected regions of Uttarakhand state:

• Nainital district 
• Mukteshwar 
• Ramgarh 
• Pauri Gadwal district 
• Uttarakashi district 
• Pithoragarh mountain district 
• Tanakpur 
• Jauljibi
• Munsiyari 
• Tawaghat 
• Dharma 
• Champawat district 
• Bageshwar district 
• Rudrapur: due to over flowing of Kalyani river 

What is LIDAR?

Light detection and ranging is a remote sensing instrument based on laser emitting pulses which is used to measure water depth in rivers and lakes. Central water commission has installed a LIDAR  sensor for  measurement of water flow, water level and downstream discharge In the Ganga 

GOLA RIVER : it is ordinated from the Lesser Himalayas village Paharpani and is about 50 km long, flows south Kathgodam, Haldwani finally joined to Ramganga river, a tributary of River Ganga, about 15km North East of Bareilly in Uttar Pradesh. The dam constructed on Gola river is Kathgodam. This is a rain fed river. 

KOSI RIVER : it is originated from Nainital district flows through Ramgarh finally joined the Ramganga river in Uttar Pradesh near south west of Rampur. 

• Sunderdhunga Glacier: 
• Dwali Glacier :
• Kafni Glacier:
• Lamkhaga pass( what is pass? pass is a gap or break, in high rugged terrain such as mountain ridge. It is formed when  a Glacier or stream erode away the land between areas of high terrain that provides easier routes to people to travel across mountain): 
• Lamkhaga pass, which is a 90 km long trekking route passing through the remotest Valley of the Kinnaur in Himachal Pradesh and Gangotri in Uttarakashi. 
• Lamkhaga pass connects Kinnaur district of Himachal Pradesh with  Harsil in Uttarakashi district, 230 km from Dehradun.
• This pass start from Chitkul the last village of Kinnaur district of sangla valley. 
• This pass is located near the Indio Tibetan border, and to cross the pass one needs to obtain inner line permit from the district administration of Himachal Pradesh. 
• Kinnaur district: 
• Its head quarter is in Recklong Peo.
• it is separated in 3 parts Puh ,kalpa and Nichar.
• Sutlej river originated from the lake Rakas in Tibet, west to Lake Mansarowar lake, entered into the Kinnaur district through the Shipki LA pass that joined to the lake Govind Sagar going further it obtained water from the river Beas as tributary originated in Himachal Pradesh and finally tribute to the river Chenab( originated in the Kyelang district of Himachal Pradesh) which tribute itself to the river Indus( originated in Tibet)
• Exist in Himalayan 
• Temperate Climate trees: oak, chestnut,  maple, birch, apple, alder, magnolia, apricot in lower Himalayan regions 
• In upper Himalayan regions, space vegetation, primarily hardy grasses, alpine species, Juniper, Pine,  Fire, Cypress, Rhododendron are found.
• Animal: Himachal Pradesh black bear.
• Yaks are reared by locals. 

Integrated Flood Water Management 

It includes various development infrastructure and green infrastructure projects on integrated approach for flood management in  frequent flood affected areas such as Chennai, these are:

• Construction of new storm water drainage
• Renovation of existing storm drainage
• To improve stretch and  water carrying Capacity of channels
• To upgrade storm pumping station
• To install new storm pumping station
• Construction of catch-pits in roadsides to recharge the ground water aquifer
• Rehabilitating relief camps
• To integrate flood hazard Zoning
• Real time flood information dissemination about flood risk
• Community awareness programmes on disaster related risks
• Installation of green infrastructure such as rain water harvesting 
• Improvement in land use planning.

Floods control measures:

• Retention walls on the banks of rivers 
• Check Dams  in canals  and rivers 
• Digging of ponds and ditches 
• Better drainage system
• Underground Sewerage system
• Plantation 
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