The GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers

T Nuimura,A Kozawa,P Tshering,K Tsunematsu,S Omiya,Y Hoshina,K Taniguchi,K Fujita,S Takenaka,D Lamsal,H Nagai,S Tsutaki,A Sakai

doi:10.5194/tc-9-849-2015

Abstract

Abstract. We present a new glacier inventory for high-mountain Asia named "Glacier Area Mapping for Discharge from the Asian Mountains" (GAMDAM). Glacier outlines were delineated manually using 356 Landsat ETM+ scenes in 226 path-row sets from the period 1999–2003, in conjunction with a digital elevation model (DEM) and high-resolution Google EarthTM imagery. Geolocations are largely consistent between the Landsat imagery and DEM due to systematic radiometric and geometric corrections made by the United States Geological Survey. We performed repeated delineation tests and peer review of glacier outlines in order to maintain the consistency and quality of the inventory. Our GAMDAM glacier inventory (GGI) includes 87 084 glaciers covering a total area of 91 263 ± 13 689 km2 throughout high-mountain Asia. In the Hindu Kush–Himalaya range, the total glacier area in our inventory is 93% that of the ICIMOD (International Centre for Integrated Mountain Development) inventory. Discrepancies between the two regional data sets are due mainly to the effects of glacier shading. In contrast, our inventory represents significantly less surface area (−24%) than the recent global Randolph Glacier Inventory, version 4.0 (RGI), which includes 119 863 ± 9201 km2 for the entirety of high Asian mountains. Likely causes of this disparity include headwall definition, effects of exclusion of shaded glacier areas, glacier recession since the 1970s, and inclusion of seasonal snow cover in the source data of the RGI, although it is difficult to evaluate such effects quantitatively. Further rigorous peer review of GGI will both improve the quality of glacier inventory in high-mountain Asia and provide new opportunities to study Asian glaciers.

Highlights

The state and fate of Asian glaciers (Bolch et al, 2012) have important implications for both regional water resources (e.g. Immerzeel et al, 2010; Kaser et al, 2010) and future sea level rise (e.g. Radicand Hock, 2011; Gardner et al, 2013)
We describe the materials and procedures used to delineate glacier outlines over high-mountain Asia and show preliminary comparisons of our GAMDAM glacier inventory (GGI) to the Randolph Glacier Inventory (RGI) and a glacier inventory produced by Bajracharya and Shrestha (2011) (ICIMOD inventory; ICIMOD: the International Centre for Integrated Mountain Development, Kathmandu, Nepal) for the Hindu Kush–Himalayan (HKH) region
We evaluated the spatial distributions of glacier number, area, and the area-weighted mean of median elevation for each 0.5◦ grid cell to identify differences between the GGI and the ICIMOD inventories (Fig. 16)

Summary

Introduction

The state and fate of Asian glaciers (Bolch et al, 2012) have important implications for both regional water resources (e.g. Immerzeel et al, 2010; Kaser et al, 2010) and future sea level rise (e.g. Radicand Hock, 2011; Gardner et al, 2013). Immerzeel et al, 2010; Kaser et al, 2010) and future sea level rise (e.g. Radicand Hock, 2011; Gardner et al, 2013). Glacier hypsometry (area–elevation distribution) directly affects estimates of mass balance, discharge, and modelled contribution to sea level rise (Raper and Braithwaite, 2005), while uncertainty in glacier outline influences estimates of mass changes using laser altimetry (Kääb et al, 2012; Gardner et al, 2013). In December 2014, the second Chinese glacier inventory was released. This new data set has not been incorporated into the RGI ver. A small number of the glaciers used in the RGI are undated (Pfeffer et al, 2014)

Objectives

Methods

Results

Discussion

Conclusion