The Hunza River basin is economically important for both China
and Pakistan as the China-Pakistan Economic Corridor (CPEC)
passes through it. The basin is highly glaciated and there is
a great risk of glacial lake outburst floods (GLOFs).
A recent study that we were part of investigated the potential
GLOF risk along the Karakoram highway. The study used both field-based
data and remote sensing techniques to understand the formation and
behavior of moraine-dammed glacier lakes and recommends considering
these risks in the formulation of future policies.
Based on 40 years of observation of the Karakoram glaciers, the study
concludes that surging and debris-covered glaciers have a higher risk
of causing GLOFs. It also concludes that surge-type and non-surge-type
glaciers have behaved similarly with respect to recent mass changes.
Glacier surge is a common phenomenon in the region. The recent surge
of Khurdopin Glacier in 2017 created the Khurdopin glacial lake in the
Shimshal Valley of the Hunza River basin. Glacial lakes are a major
source of freshwater in some areas but, when their dams suddenly breach,
they can cause catastrophic floods and pose a great threat to the people
and infrastructure in downstream areas.
The severity of damage from GLOFs increases as the elevation and volume
of the glacial lakes increases, and if the settlements and infrastructure
downstream is close in proximity. Many potential lakes in the study area
have the capacity to damage infrastructure including roads and highways.
In the past fifty years, several GLOF events in the area have been reported,
especially in the eastern part of the CPEC region. The recent GLOF event
triggered by the Shisper Glacier surge damaged the Karakoram Highway,
causing it to shut down for some time.
Temperature rise is one of the main driving forces causing expansion of
glacial lakes. Many glaciers are also retreating in this area. Closer investigation
of Khurdopin Glacier’s surges revealed both that there is a presence of
the thermal phenomenon – when the basal ice starts melting, it causes
basal sliding that in turn causes these surges – and that the retreat
of the glacier is leading to the expansion of Passu glacial lake. The
study also revealed that a maximum increase in lake area occurred below
3500 masl, demonstrating a situation favorable for water resource management.
Published in Dawn, May 19th, 2021
Provided by the IKCEST Disaster Risk Reduction Knowledge Service System