Survey report of Project . Project Title Vulnerbility Assessment of Potential Glacier Lake Outburst Flood event in Passu Lake ,Gilgit Baltistan,Pakistan

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Field Survey Report
Project Title
VulnerabilityAssessmentofPotentialGlacialLakesOutburstFloods(GLOFs)EventsinPassuLake
Description
On 26th
August 2013, a survey was conducted by me and my post graduate
colleagues at Passu Lake in Hunza Basin, Pakistan .The purpose of this survey was to
identify the reasons behind Passu Glacier Lake Outburst Flood (GLOF) event in 2008
and 2010 and to validate the modeled flood extent. These events destroyed a hotel, many
vacant houses and a bridge at Karakoram Highway (KKH).
Passu village is a small village near KK Highway that runs along Hunza River.
The village is located between Batura and Passu Glaciers. During this survey we acquired
a wealth of knowledge about the village by the local residents. Passu is a Turkish
language word that means Cold water. The population of the village is about 1,200
people and there are around 120-150 households. Most of the buildings in the village are
single story and earthquake proof. Almost half of the population lives downside of the
Hunza River. Passu village residents have a very high literacy rate and according to them
almost 100 percent of their population is literate. Main economic activities of this area
are trade with China, tourism and transportation. Passu is also a mineral rich area and has
large reserves of marble, gold and uranium. Some other primitive settlements along
Hunza River and near Passu village are Gulmit and Girja villages.
During the survey we have interviewed number of local residents of Passu village.
Since 2008 flood was relatively big as compared to 2010 event, village people mostly
talked about the 2008 Passu Glacier Lake outburst. As per their observations, the lake
burst suddenly in 2008 without any warning. They have a belief that it was due to some
unknown activity and according to them its cause could not be ascertained. It was also
important to note that the lake burst during the night time but the village was evacuated
according to a local person’s statement. They also mentioned about the presence of a hot
water spring in nearby Gilgit valley with which, according to them, the outburst event
might be connected. They also told us that the lake water was in black color at the time of
outburst. One of the local residents also took pictures and made a video clip when this
lake burst in 2008. Although we could not procured these pictures/video, but were given
the contact information of the agency that, at present, is the custodian of these pictures.
The local residents also confirmed that the GLOF event of 2008 did not harm Passu
village and it was completely safe although the agriculture and cultivated land were
largely impacted by the flood water. We also enquired about the Passu glacier temporal
changes and came to know that glacier terminus is continuously retreating from 1970s to
until now.

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Local residents also pointed out the difficulties they have to face now-a-days due
to the damaged KKH while trading vegetables and fruits and buying basic necessities
from Hunza valley. Due to the formation of artificial lake after Attabad landslide event
in January 2010, KKH was partially damaged and submerged in the lake water. Now they
have to travel by boats to get to the Hunza valley.
Water and Power Development Authority (WAPDA), Pakistan has installed an
Automatic River Level (ARL) station in collaboration with International Centre for
Integrated Mountain Development (ICIMOD) at Passu on 8th
October 2010. At this
station they are collecting daily summer data from 2011 under Glacier Research Center at
WAPDA Lahore. WAPDA data (2011, 2012 and 2013) are presented in Table 2. We
have also interviewed employees of WAPDA, who are working in the valley and
monitoring the flow coming out of the Passu Lake. WAPDA employees gave us useful
information about discharge/flow from Passu Lake. They educated us about the time
periods when the flow is maximum or minimum. Each year the maximum flow of lake is
recorded in August because June - August is the snow melting season. Pakistan
Meteorological Department (PMD) has also set up high monitoring stations at Passu
glacier.
Early in our study we have performed hydraulic modeling of the lake outburst
using HEC-RAS/GeoRAS software and delineated flood area. We have assumed
discharge values using empirical formulas for the worst case scenario. For our analysis
we assumed that if the lake bursts, then all of its water will be released suddenly into the
river. We validated the results of the model with the actual flood extent. Now since we
have flow/discharge data, we will run our model again for two more real scenarios
accounting for maximum and minimum flows.
Mohammad Danish Siddiqui
September 17, 2013
Acknowledgements: First I would like to appreciate and express my special gratitude to my
colleagues Mr. Saad Ul Haq and Mr. Muhammad Abdullah for their presence and support
during this field survey. I sincerely thank my respected mentor Dr. Arjumand Zaidi for her
guidance about this field trip. I am blessed to have a caring, motivating and inspirational mentor
like her. Thank you Ma’am once again. I would also like to thank Passu village residents Mr.
Azam, Mr. Shah Faisal and Mr. Sher o Lalick who gave me tremendous information about
our study area. They were extremely friendly and they helped us a lot during our field visit. I am
grateful to WAPDA staff Mr. Mohammad Aslam and Mr. Imtiaz Hussain for providing us
Passu Lake flow data. Last but not the least, I would like to acknowledge and thank my co-
fellow Ms. Zeenat Yasmeen for her constant cooperation and equal contribution in completing
this study.

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FIELD SURVEY DATA
Table 1: Passu Lake Coordinates (GPS Survey)
Observation
Points
Northing Easting
Elevation
(a.m.s.l)
(m)
001 N36°27.538’ E074°52.988’ 2563
002 N36°27.538’ E074°52.988’ 2563
003 N36°27.514’ E074°52.997’ 2562
004 N36°27.501’ E074°52.987’ 2561
005 N36°27.497’ E074°52.983’ 2561
006 N36°27.494’ E074°52.979’ 2562
007 N36°27.491’ E074°52.958’ 2565
008 N36°27.484’ E074°52.955’ 2565
009 N36°27.482’ E074°52.958’ 2567
Table 2: Flow Data (WAPDA)
Maximum flow 2700cusec/1.53gage
Average velocity 12feet/sec
Wind speed 15knot exceed
Minimum water
discharge
0.79m

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PICTURE GALLERY
Figure 1: Mr. Azam (resident) sharing his knowledge Figure 2: View of Passu Lake
Figure 3: Agriculture land – Wheat crop Figure 4: View of Passu Village

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Figure 5: ICIMOD –WAPDA ARL Station Figure 6 : WAPDA Staff sharing knowledge with us
Figure 7: Staff Gage at Passu Lake Figure 8 : Passu Glacier Terminus retreating
progressively
(A = where it was in 70s, B = where it is now)
A
B