IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
4.2 Study of a flashflood over the Sutlej river in Himachal the Spiti and other tributaries join the Sutlej River. The Sutlej 
  
  
  
      
    
  
  
ge Pradesh (on August 1 2000) using temporal satellite data River is flowing through a deep gorge for a major portion of 
ba the Tibetan plateau and incidentally falling under main 
of 4.2.1 Introduction: tectonic belt of the Himalayas and more often affected by 
ied earthquakes. 
ter There was a flash flood over the Sutlej River on August 1, 2000 : 3 2 
nt and it caused severe damage to public property in the form of 42-5 Salient observations of the study: 
S- washing away bridges, damage to hydel-power stations to the : : : 
rly extent few hundred crore rupees besides, causing loss to 105 D The Tsomorari Lake: is one of the largest lakes in the 
18, human lives. The 320 Kms long Indo-Tibet road was blocked to ladakh region with about 180 sq.kms area (28 Kms long and 8 
nd traffic due to floods and landslides. Maximum damage was Kms wide). Prior to this study, the lake was not considered as 
ge reported from Rampur, Neogli, Karcham and Tatta pani a part of Sutlej River basin. However, during the study it was 
an settlements. The Napha Jhakri hydel power Project (1500 MW), observed (through high-resolution satellite data) that the 
le" the Bhada hydel project (126 MW capacity), the Ghanvi hydel Tsomorori Lake is well connected to the Sutlej River. It also 
ide project (22 MW) and Chaba power projects were badly noticed that the southern end of the lake was blocked by a 
ut damaged by the swollen waters of the Sutlej River. It was huge alluvial fan. In the literature it was mentioned that 
de reported that a sudden rise in water level from 12 Mts. to 20 majority of the lakes in the Tibet upland area were formed by 
ent Mts., at midnight of 1* August and in a short duration (about 6 blockage of river courses by landslides/ mudflows, which in 
the hrs), the discharge in the Sutlej River rose to 1,80,000 cusecs turn they were initiated by earthquakes. Analysis of satellite 
the from a normal flow of 40,000 cusecs. An attempt has been data pertaining to pre as well as post flood events Clearly 
ver made here to identify the probable causes of this unusual flash indicating, some change in the volume of water, especially in 
the flood in Himachal Pradesh, using temporal data of IRS-1C/ID the southern end of the lake. Further, analysis of temporal 
Ty PAN, LISS-III, WIFS and Radarsat data covering the pre as well WIFS and LISS III for the period May to August 2000 show a 
of as post flood event (Fig.2) gradual decrease in the snow cover extent. Even a small 
rea change in the lake water volume is enough to create the 
ied 4.2.2 Data used: discharge noticed in the Sutlej River during flood. In view of 
Ive this, this lake has to be monitored periodically to avoid future 
Md A) Satellite/sensor data Path-Row _ Date of acquisition* disasters. 
hu AT. E 
il), ES ID PAN II T Cr qun T9 ame II) Impounded water body of the Sutlej River: Temporal 
is IRS-1D-PAN P96-R47/48 Aug 06 2000 data of IRS-1C/1D-LISS-TII, WIFS and IRS-1B, LISS-II was 
the RADARSAT voli. Aug 08 2000 studied by NRSA suggested that there was an impounded water 
ng IRS-1D WIFS P96-R48 Jun 25 2000 body in the Sutlej River bed (at 31 3729"N Lat & 79'31'17"E 
am IRS-1C WIFS P96-R48 Jul 08 2000 Long) and the same was present since April 1997. Further, the 
ont IRS-1D WIFS P96-R48 Jul 14 2000 study also suggesting that there have been fluctuations in the 
the IRS-1C WIFS P96-R48 Jul 23 2000 extent of water from time to time. Interestingly by 31* July 
the IRS-1C WIFS P96-R48 Jul 27 2000 2000 it attains maximum areal extent. The Landsat-TM data 
nai IRS-1C WIFS P95-R48 Aug 01 2000 acquired on August 6 2000 clearly shows a breach at this 
nts * These data sets are studied jointly by NRSA & ADRIN location and significant reduction in the volume of water. 
in covering the Tso Morari Lake Unfortunately, cloud free imagery not available for August 1, 
d M AR 2000. Probably, this water body could have breached some 
; ^ where during 31, July 2000 and caused the flash flood in the 
N) B Farm Ee PARE aed So fram Database early hours of August 1, 2000. Hence, it is suggested that this 
the Source breached (impounded) water body might have contributed the 
m - 17-06-2000 3196 N7840E 49 USGS flash flood to certain extent. (Fig.2) 
0 database 
ter 05-07-2000  33.88°N79.80°E 14.4 USGS IRS-1C LISS Il 29-Apr-1997 
database = 20e gn " Hir 
17-07-2000 34.15°N79.65°E 4.7 USGS database a) " s : : 
ne 19-07-2000 30.87°N79.50°E 3.3 IMD database 
e 
12, C) Media/Newspaper reports /TV coverages 
D) Website: www. Expediamaps.com 
E) Maps: ONC/TPC maps on 1:10,00,000 & 1:5.00.000 
nt scales 
ide 
4.2.3 Objectives of the study: 
m The main objective of this study is to identify the Probable 
  
cause(s) of the flashflood that occurred on August 1, 2000 over 
TY the Sutlej River. Temporal Satellite data pertaining to Pre as 
well as post flood event was analyzed to find out the major 
causes of the flood. Following (probable) options were 
considered for the flashflood of August 1 2000. I) Breach of 
lakes and water impounded areas in the upper catchment areas. 
II) Blockade and subsequent breach of impounded water due to 
de landslides/ earthquake III) Cloud burst and heavy precipitation 
90, /snowmelt in the upper catchment area IV) Sudden rise in water 
wil levels of large glacial lake like Manasarovar. 
ty 
de 4.2.4 Sutlej River Basin: 
in 
at The Sutlej is a major tributary of the Indus River, has its origin 
near the Manasarovar Lake at an elevation of 4,570 Mts., 
above MSL. It flows through the Tibetan plateau and enters 
  
into Himachal Pradesh. Before it enters into Indian territory, 
635