Volume 2

Volume: II Section: 1 Page No: 1

Comprehensive CAT Plan of Satluj River Basin

Section 1:

Introduction

Disasters in Context of Himachal Pradesh*1:

Geologically the Himalayas are considered to be the youngest mountain chain in the

world and are still in the building phase. Himalayas were formed about 45 million years

ago, when the Indian Plate collided with Eurasian Plate at the rate of 15cm per year. The

Indian Plate is still moving northwards today into the Eurasian Plate at the rate of about

2cm per year. As a result of this the Himalayas are rising at the rate of about 5mm per

year. This means that the Himalayas are still geologically active. When two plates move

sideways against each other (at transform plate boundary), there is tremendous friction,

which makes the movement jerky. The plates slip, then stick, as the friction and

pressure build up to incredible levels. When the pressure is released suddenly, and the

plates jerk apart, the result is an occurrence of an earthquake. For this reason,

earthquakes are frequent in the entire Himalayan region.

The state of Himachal Pradesh is in the Northwestern Himalayas. It is environmentally

fragile and ecologically vulnerable. Natural hazards are a matter of immediate concern to

the state of Himachal Pradesh as every year the state experiences the fury of nature in

various forms-like earthquakes, cloudburst, flash floods, landslides, snow avalanches

droughts etc. The fragile ecology of the mountain state coupled with large variations in

physio-climatic conditions has rendered it vulnerable to the vagaries of nature. The

incidence of cloudbursts in the last few years is indicative of greater impending disasters

ito come in future. landslides and snow avalanches continue to inflict widespread harm

and damage to human life as well as property. The roads that are the state’s lifeline are

repeatedly damaged, blocked or washed away by one or other acts of nature.

The state as a whole is vulnerable to different kinds of disasters, natural as well as man-

made in nature. The major natural disasters or hazards which the state has experienced

over the years are as follows:

Earthquakes Landslides

Flash floods Cloud bursts

Avalanches Hailstorms/Droughts

EARTHQUAKES

Himachal Pradesh is in very sensitive seismic zones. It falls in zone V and IV as per the

Seismic Zoning Map of India. ( Ref : IS: 1893-1984 Fourth Revision. Earlier there were

five seismic zones which have been further narrowed to four zones now. According to the

Foreword to the seismic code IS: 1983-1984, the general basis of zoning is as follows:

Zone V: Covers the areas liable to seismic intensity IX and above on Modified Mercalli

Intensity Scale. This is the most severe seismic zone and is referred to as the

Very

High Damage Risk Zone.

Zone IV: Gives the area liable to MM VIII. This zone is second in severity to zone V. This is

referred to as the High Damage Risk Zone.

Zone III: The associated intensity is MM VII. This is termed the Moderate Damage Risk

Zone.

Zone II: The probable intensity is MM VI. This zone is referred to as the Low Damage Risk

Zone.

1 Natural Disasters and Climate Change - Himachal SoE



From the perusal of seismic zoning map of Himachal Pradesh (Fig.II) it is seen that 32 %

of the total geographical area is prone to the severest seismic risks as it falls into the

Very High Damage Risk Zone V. It was subjected in 1905 to one of the most giant

earthquakes of the recorded seismic history of India having a magnitude of 8.0 on the

openended Richter Scale in which 20,000 people lost their lives, the towns of Kangra and

Dharamshala were razed to the ground and no government functionary was left alive to

report the happening to the higher authorities. It shook an area of more than 416000

km2 in and around the present Himachal Pradesh. A maximum Intensity X on Rossiforel

Scale was observed in the epicentral area which, when interpreted on the new current

Modified Mercalli Scale, would be between X and XI. There have been 250 earthquakes

of magnitude 4.0 and more including more than sixty earthquakes with magnitude 5.0 or

more, which rocked the state of H.P. and adjoining areas of J&K and Uttranchal Pradesh

in the last 90 years. The Kinnaur earthquake of January 19, 1975 (M=6.7) and the

Dharamshala earthquake of April 26,1986 (M=5.7) are well recorded in respect of

damages caused and loses incurred. A list of earthquakes of M=4.0 or more is given in

Table II which had their epicenters either within or close to the state boundary.

Earthquakes having magnitude 4 or more on the Richter Scale in Himachal Pradesh

during the last 200 years.

S.No Year Month Day Magnitude Coordinates Tentative location

1 1809 - 5.5 30042’00” Near Labrang

780 30’00” (Distt.Kinnaur)

2 1827 9 5.5 32030’00” Near Dalhousie

76000’00” (Distt. Chamba)

3 1856 4 7 5 31000’00” Near Ranhog

77000’00” (Distt.Solan)

4 1858 8 11 5 3107’12” Shimla

77010’12” (Distt.Shimla)

5 1865 4 11 — Shimla region

6 1905 4 4 8 32018’00” Karari Dal

76015’00” (Distt.Kangra)

7 1906 2 28 7 32000’00” Near Karshing

770 00’00” (Distt.Kullu)

8 1930 5 11 5.5 31042’00” Shila Kiepr

77000’00” (Distt. Mandi)

9 1940 4 7 — 31 05 Near kali Hatti

77 00 Distt. Shimla

10 1945 6 22 6.5 32036’00” Minu


11 1947 7 10 6.2 32036’00” Minu

75054’00” (Distt. Chamba )

12 1950 8 12 5.5 32036’00” Minu


13 1951 9 22 6.4 32 36 East of Dhan Kanda

76 30 (Distt. Chamba)

14 1962 9 15 5.5 31054’00” Near Dehra Gopipur

76012’00” (Distt.Kangra)

15 1965 2 21 4.5 32 14 Near Bara Banghal,

76 54 (Distt. kangra)

16 1967 9 20 — 32 36 Near Rajpura,


17 1968 5 11 4.9 32 22 Near Atrori,


18 1969 1 23 4 32 14 Near Trilokpur,

76 03 (Distt. Kangra)

19 1970 3 5 4.9 32 24 Near Sani,




20 1972 1 29 4.7 32 51

75 54

21 1973 12 16 4.9 32 17 Near Mordhu,


22 1974 11 16 4.8 32 50 Tissa,


23 1975 10 30 5.2 32 54 Near Bhujara,


24 1975 12 11 5.1 32 50 Near Jankar,

76 58

(Sumdo, Lahaul &

Spiti)

25 1975 12 10 5 32 49 Near Chhajaut,


26 1975 1 19 6.7 31056’24” Distt. Kinnaur

78031’48”

27 1975 2 2 5.1 32033’36” Indo China Border

78053’00”

28 1975 7 19 5.1 31057’00” Near Chnago

78035’24” (Distt. Kinnaur)

29 1975 7 29 5.5 32034’12” Near Kanum


30 1975 2 10 5.3 32057’00” Near Janu Pass

76006’ 00” (Distt. Chamba)

31 1975 2 11 5 33000’00” Near Sathrundi


32 1976 1 7 5.3 32058’12” Dunchili Gad


33 1976 1 9 4.7 32 59 Along J&K Border

76 01

34 1976 2 5 5 31014’24” Near Chebri

77001’48” (Distt. Shimla)

35 1976 4 10 4.5 32 43 Near Balthal Got,


36 1976 4 16 4 32 52 Near makkan,


37 1976 7 6 5.1 32026’24” Near Raksham


38 1976 9 8 5.3 32014’08” Near Baspa origin


39 1977 2 19 5.4 31048’00” Near Rangbar

78025’48” Thachang

(Distt. Kinnaur)

40 1977 3 27 5.1 32040’12” Lenchichi


41 1978 6 14 5 32014’24” Near SinghauPass,

76036’36” along Kangra Border

(Distt. Chamba)

42 1979 1 19 4.1 32 22 Near Chandota Pass,


43 1980 5 29 4.2 31 33

76 33

44 1980 9 4 4 32 00 Near Pajaund,

76 54 (Distt. Mandi)

45 1980 11 26 4 32 29 Near Khaddar,


46 1981 2 14 4 32 35 Near Bara Kanda,


47 1981 6 19 4.5 32 43 Near Lohari,




48 1981 6 13 5 31049’12” Nalpaya Thach


49 1981 5 28 5.2 31049’48” Barling


50 1982 5 18 4 32 25 Near Chagrauta,


51 1983 2 27 5.3 32036’00” Khadi Thach


52 1983 4 13 4 32 46 Near Tikkri Khas,


53 1985 3 11 4.8 31 15 Near Malaun,

77 00 (Distt. Shimla)

54 1985 12 29 4.9 32 37 Near Theru,


55 1986 4 26 5.5 32019’00” Near Nag Dal

76024’00”

(Boundary of

Distt.Chamba &

Kangra)

56 1987 6 10 4.7 31 55 Near Daton,


57 1987 12 26 4.3 32 07 Near Dewal Khas,


58 1991 6 23 4.6 32 18 Near Gataunda,

76 42 (Distt. Shimla)

59 1992 1 26 4.5 32 16 Near Bhagsu Nath,


60 1992 2 13 4.5 32 37 East of Dhan Kanda,


61 1992 9 6 4.6 32 25 Near Darkund,


62 1996 5 9 4 32 50 Near Kuntka Matha,


63 1996 5 23 4.2 32 42 Near East of Kagal

76 29 Dhar(Distt. Chamba)

64 1996 7 14 4.1 32 37 Near East of Dhan

76 31 Kanda(Dist.Chamba)

65 1996 9 14 4.6 32 49 Near Kala Ka

76 22 Bhandar,

(Distt. Chamba)

66 1997 7 29 4.7 31 33 Near Baldwara,

76 48 (Distt. Mandi)

67 1997 8 13 4.2 31 12 Near Jajjar,

76 41 (Distt. Solan)

68 1998 10 17 4.5 32 12 Near Kandha,


69 1999 5 30 4.9 31 48 36 Near Miyang Lung,

78 54 36 (Distt. Kinnaur)

70 1999 1 8 4.2 31 26 24 Near Mehog,

77 18 00 (Distt. Mandi)

71 1999 5 30 4.9 31 48 36 Near Miyang Lung,


72 1999 1 8 4.1 31 22 48 Near Karsog,

77 17 24 (Distt. Mandi)

72 2000 4 28 4.1 31 30 36 Near mehbar,

78 15 00 (Distt. kinnaur)

73 2000 8 28 4.5 32 01 48

78 18 00



74 2000 9 26 4 30 55 12

75 39 00

75 2000 6 17 4.3 31 48 00 Near Nalpaya,


76 2001 6 17 4.2 32 42 36

78 26 24

77 2001 1 22 4 31 04 12 Along Uttranchal

77 55 48 Border

78 2001 2 23 4 30 55 48 Along Uttranchal

78 00 00 Border

79 2001 9 18 5.1 33 13 12

75 36 36

80 2001 14 4.7 32 31 12 Near Pundla,

76 06 00 (Distt. Chamba)

81 2001 23 4.6 33 07 12

75 40 12

82 2002 1 27 5.1 33 06 36

75 49 48

83 2002 3 17 4.1 32 46 48

75 55 48

84 2002 2 17 4.1 33 06 00

75 40 48

It is also seen that according to the seismic zoning map of the state, five districts,

namely Chamba, (53.2%) Hamirpur(90.9%),Kangra (98.6%),Kullu (53.1%) and Mandi

(97.4%) have 53 to 98.6 percent of their area liable to the severest designed Intensity

of MSK IX or more, the remaining area of these districts being liable to the next severe

Intensity VIII. Two districts, Bilaspur (25.3%) and Una (37.0%) also have a substantial

area in MSK IX and the rest in MSK VIII. The remaining districts Shimla, Lahaul & Spiti,

Sirmour,Kinnaur and Solan are liable to Intensity VIII. As a whole nearly 31.94 % of the

total geographical area of the state falls in the high seismic risk zone.*

The Satluj flows from the high-elevation arid parts of the eastern Himalayan ranges. This

is the region of the mountain desert. This orographic rainfall barrier at about 3000 m

changes abruptly into very humid sectors further downstream with mean annual

precipitation of 3 m. This significant increase in precipitation is also reflected by

amplification in sediment flux, hill slope processes, and vegetation cover. The climatic

transition zone, bounded to the east by the orographic rainfall threshold barrier, is

characterized by pronounced geomorphic changes, such as a decrease in river sinuosity,

steepening channel gradients and hill slopes over a short distance of a few kilometers.

Landslides are a frequent occurrence in Satluj River Basin due to high slope instability,

weak geology, seismic activity, deforestation, faulty land use and unplanned

construction. The mass of earth, which roles down or slips down the slopes becomes

loose and is fast eroded by the rain. During field survey, at several locations it was also

noted that irrigated orchards on terraced uplands having rocky sub-stratum generally

have saturated soil profile. The sub-surface flow moves down the slope and saturates the

soil mass located on steep slopes below the orchards. This saturation not only increases

the weight of the soil mass but also reduces soil strength upon wetting. This

phenomenon becomes the cause of landslides.

Numerous landslide deposits dammed the Sutlej River and its tributaries in the past and

acted as sediment traps storing large quantities of sediment. 2 Thus the Himachal

Pradesh faces a gigantic problem of soil erosion and loss of water. The hydro electric

projects mentioned above may suffer serious damages by the huge amount of silt

2 Bookhagen, B.; Thiede, R. C.; Strecker, M. R. , 3. Mass Movements, Erosion Patterns and Sediment

Transport along the Sutlej River (NW-Himalaya)



coming into their turbines and forcing closure for long periods during the peak

generating hours. The silt though directly affects the hydel projects but indirectly causes

many uncountable damages to electricity generation, financial loss, losses to electricity

user and so on. Apart from these, silt load harms the farming lands during monsoon

damages agriculture to the extent that people shift their occupation due to huge losses.

The anthropogenic aspects, geology, soil type, rains and snow are main reasons for

landslides in this region. They cause severe landslides resulting in endangering human

life, loss to biodiversity as well as to infrastructure such as roads and such other

development. These issues can only be handled if we have clear knowledge of the

catchments of the river Satluj and catchments of its tributaries.

NERIL’s Approach NERIL has conducted field survey in all

the MWs and Sub-Catchments for

primary data collection. Each and

every landslip/ landslide in all the MWs

and Sub-Catchments has been visited

and details like dimensions, soil type,

degree of slope, damage done, reason

for occurrence, suggested measures,

GPS location, photograph etc. are

recorded in Table 9 of checklist. In

addition to it all the major landslides

were further visited by experts and

civil engineers for verification. The

treatment measures include bio-

engineering and civil engineering for

mitigation. Since bio-engineering treats only surface erosion therefore civil engineering

structures have been suggested to retain that surface. In the last few years engineering

technologies have evolved to provide solutions for debris flow, landslides, land slips and

so on.

Section 2 of this volume provides a compilation of all the endangering landslides which

need urgent engineering intervention. These details are repeated in the respective sub-

catchment volumes also. Section 3 of this volume contains landslide/ landslip description

and mitigation with costing and section 4 contains estimates of landslide/ landslip.

Volume 2

Documents

Transcript of Volume 2