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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 manmade in nature. The major natural disasters or hazards which the state has experienced over the years are as follows: Earthquakes Flash floods Avalanches
Landslides Cloud bursts 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:
Zone IV: Zone III: Zone II:
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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. 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. The associated intensity is MM VII. This is termed the Moderate Damage Risk Zone. The probable intensity is MM VI. This zone is referred to as the Low Damage Risk Zone.
Natural Disasters and Climate Change - Himachal SoE Comprehensive CAT Plan of Satluj River Basin
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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
1
1809
2
Day
Magnitude
Coordinates
Tentative location
-
5.5
1827
9
5.5
3
1856
4
7
5
4
1858
8
11
5
30042’00” 780 30’00” 32030’00” 76000’00” 31000’00” 77000’00” 3107’12” 77010’12”
5 6
1865 1905
4 4
11 4
— 8
7
1906
2
8
1930
5
9
1940
4
10
1945
6
11
1947
7
12
1950
8
13
1951
9
14
1962
9
15
1965
2
16
1967
9
17
1968
5
18
1969
1
19
1970
3
Near Labrang (Distt.Kinnaur) Near Dalhousie (Distt. Chamba) Near Ranhog (Distt.Solan) Shimla (Distt.Shimla) Shimla region Karari Dal (Distt.Kangra) Near Karshing (Distt.Kullu) Shila Kiepr (Distt. Mandi) Near kali Hatti Distt. Shimla Minu (Distt. Chamba) Minu (Distt. Chamba ) Minu (Distt. Chamba) East of Dhan Kanda (Distt. Chamba) Near Dehra Gopipur (Distt.Kangra) Near Bara Banghal, (Distt. kangra) Near Rajpura, (Distt. Chamba) Near Atrori, (Distt. Chamba) Near Trilokpur, (Distt. Kangra) Near Sani, (Distt. Chamba)
32018’00” 76015’00” 28 7 32000’00” 770 00’00” 11 5.5 31042’00” 77000’00” 7 — 31 05 77 00 22 6.5 32036’00” 75054’00” 10 6.2 32036’00” 75054’00” 12 5.5 32036’00” 75054’00” 22 6.4 32 36 76 30 15 5.5 31054’00” 76012’00” 21 4.5 32 14 76 54 20 — 32 36 76 06 11 4.9 32 22 76 22 23 4 32 14 76 03 5 4.9 32 24 76 29 Comprehensive CAT Plan of Satluj River Basin
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1972
1
29
4.7
21
1973
12
16
4.9
22
1974
11
16
4.8
23
1975
10
30
5.2
24
1975
12
11
5.1
25
1975
12
10
5
26
1975
1
19
6.7
27
1975
2
2
5.1
28
1975
7
19
5.1
29
1975
7
29
5.5
30
1975
2
10
5.3
31
1975
2
11
5
32
1976
1
7
5.3
33
1976
1
9
4.7
34
1976
2
5
5
35
1976
4
10
4.5
36
1976
4
16
4
37
1976
7
6
5.1
38
1976
9
8
5.3
39
1977
2
19
5.4
40
1977
3
27
5.1
41
1978
6
14
5
42
1979
1
19
4.1
43
1980
5
29
4.2
44
1980
9
4
4
45
1980
11
26
4
46
1981
2
14
4
47
1981
6
19
4.5
32 75 32 76 32 76 32 76 32
51 54 17 01 50 08 54 00 50
76 58 32 49 76 11 31056’24” 78031’48” 32033’36” 78053’00” 31057’00” 78035’24” 32034’12” 78029’24” 32057’00” 76006’ 00” 33000’00” 76010’12” 32058’12” 7607’12” 32 59 76 01 31014’24” 77001’48” 32 43 76 30 32 52 76 00 32026’24” 78021’00” 32014’08” 78045’36” 31048’00” 78025’48” 32040’12” 78039’36” 32014’24” 76036’36” 32 76 31 76 32 76 32 76 32 76 32
22 28 33 33 00 54 29 24 35 37 43
Comprehensive CAT Plan of Satluj River Basin
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Near Mordhu, (Distt. Chamba) Tissa, (Distt. Chamba) Near Bhujara, (Distt. Chamba) Near Jankar, (Sumdo, Lahaul Spiti) Near Chhajaut, (Distt. Chamba) Distt. Kinnaur Indo China Border Near Chnago (Distt. Kinnaur) Near Kanum (Distt. Kinnaur) Near Janu Pass (Distt. Chamba) Near Sathrundi (Distt. Chamba) Dunchili Gad (Distt. Chamba) Along J&K Border Near Chebri (Distt. Shimla) Near Balthal Got, (Distt. Chamba) Near makkan, (Distt. Chamba) Near Raksham (Distt. Kinnaur) Near Baspa origin (Distt. Kinnaur) Near Rangbar Thachang (Distt. Kinnaur) Lenchichi (Distt. Kinnaur) Near SinghauPass, along Kangra Border (Distt. Chamba) Near Chandota Pass, (Distt. Chamba)
Near Pajaund, (Distt. Mandi) Near Khaddar, (Distt. Chamba) Near Bara Kanda, (Distt. Chamba) Near Lohari,
&
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1981
6
13
5
49
1981
5
28
5.2
50
1982
5
18
4
51
1983
2
27
5.3
52
1983
4
13
4
53
1985
3
11
4.8
54
1985
12
29
4.9
55
1986
4
26
5.5
76 00 31049’12” 78027’36” 31049’48” 78025’48” 32 25 76 24 32036’00” 78034’12” 32 46 76 14 31 15 77 00 32 37 76 06 32019’00” 76024’00”
56
1987
6
10
4.7
57
1987
12
26
4.3
58
1991
6
23
4.6
59
1992
1
26
4.5
60
1992
2
13
4.5
61
1992
9
6
4.6
62
1996
5
9
4
63
1996
5
23
4.2
64
1996
7
14
4.1
65
1996
9
14
4.6
66
1997
7
29
4.7
67
1997
8
13
4.2
68
1998
10
17
4.5
69
1999
5
30
4.9
70
1999
1
8
4.2
71
1999
5
30
4.9
72
1999
1
8
4.1
72
2000
4
28
4.1
73
2000
8
28
4.5
31 76 32 76 32 76 32 76 32 76 32 76 32 76 32 76 32 76 32 76
55 26 07 41 18 42 16 24 37 30 25 20 50 19 42 29 37 31 49 22
31 76 31 76 32 76 31 78 31 77 31 78 31 77 31 78 32 78
33 48 12 41 12 32 48 54 26 18 48 54 22 17 30 15 01 18
36 36 24 00 36 36 48 24 36 00 48 00
Comprehensive CAT Plan of Satluj River Basin
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(Distt. Chamba) Nalpaya Thach (Distt. Kinnaur) Barling (Distt. Kinnaur) Near Chagrauta, (Distt. Chamba) Khadi Thach (Distt. Kinnaur) Near Tikkri Khas, (Distt. Chamba) Near Malaun, (Distt. Shimla) Near Theru, (Distt. Chamba) Near Nag Dal (Boundary of Distt.Chamba & Kangra) Near Daton, (Distt. Chamba) Near Dewal Khas, (Distt. Kangra) Near Gataunda, (Distt. Shimla) Near Bhagsu Nath, (Distt. Kangra) East of Dhan Kanda, (Distt. Chamba) Near Darkund, (Distt. Chamba) Near Kuntka Matha, (Distt. Chamba) Near East of Kagal Dhar(Distt. Chamba) Near East of Dhan Kanda(Dist.Chamba) Near Kala Ka Bhandar, (Distt. Chamba) Near Baldwara, (Distt. Mandi) Near Jajjar, (Distt. Solan) Near Kandha, (Distt. Kangra) Near Miyang Lung, (Distt. Kinnaur) Near Mehog, (Distt. Mandi) Near Miyang Lung, (Distt. Kinnaur) Near Karsog, (Distt. Mandi) Near mehbar, (Distt. kinnaur)
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2000
9
26
4
75
2000
6
17
4.3
76
2001
6
17
4.2
77
2001
1
22
4
78
2001
2
23
4
79
2001
9
18
5.1
80
2001
14
4.7
81
2001
23
4.6
82
2002
1
27
5.1
83
2002
3
17
4.1
84
2002
2
17
4.1
30 75 31 78 32 78 31 77 30 78 33 75 32 76 33 75 33 75 32 75 33 75
55 39 48 27 42 26 04 55 55 00 13 36 31 06 07 40 06 49 46 55 06 40
12 00 00 00 36 24 12 48 48 00 12 36 12 00 12 12 36 48 48 48 00 48
5
Near Nalpaya, (Distt. Kinnaur)
Along Uttranchal Border Along Uttranchal Border
Near Pundla, (Distt. Chamba)
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)
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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 bioengineering 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 subcatchment volumes also. Section 3 of this volume contains landslide/ landslip description and mitigation with costing and section 4 contains estimates of landslide/ landslip.
Comprehensive CAT Plan of Satluj River Basin