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Integrated simulation of snow and glacier melt in water and energy balance‐based, distributed hydrological modeling framework at Hunza River Basin of Pakistan Karakoram region
Author(s) -
Shrestha Maheswor,
Koike Toshio,
Hirabayashi Yukiko,
Xue Yongkang,
Wang Lei,
Rasul Ghulam,
Ahmad Bashir
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd022666
Subject(s) - glacier , glacier mass balance , snowmelt , surface runoff , snow , geology , accumulation zone , hydrology (agriculture) , structural basin , precipitation , environmental science , geomorphology , climatology , meteorology , cryosphere , geography , sea ice , ecology , geotechnical engineering , ice stream , biology
Energy budget‐based distributed modeling of snow and glacier melt runoff is essential in a hydrologic model to accurately describe hydrologic processes in cold regions and high‐altitude catchments. We developed herein an integrated modeling system with an energy budget‐based multilayer scheme for clean glaciers, a single‐layer scheme for debris‐covered glaciers, and multilayer scheme for seasonal snow over glacier, soil, and forest within a distributed biosphere hydrological modeling framework. Model capability is demonstrated for Hunza River Basin (13,733 km 2 ) in the Karakoram region of Pakistan on a 500 m grid for 3 hydrologic years (2002–2004). Discharge simulation results show good agreement with observations (Nash‐Sutcliffe efficiency = 0.93). Flow composition analysis reveals that the runoff regime is strongly controlled by the snow and glacier melt runoff (50% snowmelt and 33% glacier melt). Pixel‐by‐pixel evaluation of the simulated spatial distribution of snow‐covered area against Moderate Resolution Imaging Spectroradiometer‐derived 8 day maximum snow cover extent data indicates that the areal extent of snow cover is reproduced well, with average accuracy 84% and average absolute bias 7%. The 3 year mean value of net mass balance (NMB) was estimated at +0.04 myr −1 . It is interesting that individual glaciers show similar characteristics of NMB over 3 years, suggesting that both topography and glacier hypsometry play key roles in glacier mass balance. This study provides a basis for potential application of such an integrated model to the entire Hindu‐Kush‐Karakoram‐Himalaya region toward simulating snow and glacier hydrologic processes within a water and energy balance‐based, distributed hydrological modeling framework.