UAV-Based Survey of Glaciers in Himalayas: Challenges and Recommendations

Raaj Ramsankaran,Anil V Kulkarni,Ajay Dashora,P J Navinkumar

doi:10.1007/s12524-020-01300-7

Abstract

Role of Unmanned Aerial Vehicle (UAV)-based remote sensing (RS) applications in glaciology have increased in recent years. UAV-based RS studies on mountain glaciers are mainly focussing on obtaining accurate ultra-high-resolution data from UAV images for different glaciological applications. However, studies understanding the challenges involved during UAV surveys on complex terrains of high mountain glaciers are inadequate and they are not available for places like Himalayas. Therefore, this study aims to examine and derive strategies to minimize those challenges on such complex glacier and their margin topography. Here, UAV surveys were conducted using a fixed-wing commercial-grade off-the-shelf UAV (eBee series, SenseFly) on three glacier sites (East Rathong, Hamtah and Panchinala-A) located in different climate regimes within the Indian part of Himalayas. From the UAV collected images, ultra-high-resolution ortho-mosaicked images and Digital Elevation Models were generated at 0.1 m ground sample distance and their accuracies were assessed using the collected ground control points. Based on the challenges observed, the study recommends criteria for selection of best-suited take-off/landing locations on a mountain glacier and its margins for conducting efficient UAV surveys in the complex terrain such as in the Himalayas and possibly beyond. Recommendations reported in this article shall be useful to minimize the challenges and associated risks during UAV data acquisition using fixed-wing UAVs.

Highlights

Glaciers are perennial features that temporarily store freshwater and they comprise only a fraction of the Cryosphere region
This article reports the authors experiences obtained from Unmanned Aerial Vehicles (UAV) surveys conducted using fixedwing off-the-shelf UAV on the glaciers located in Western and Eastern Indian Himalayas
From the UAV collected photos, ultra-high spatial resolution (0.1m GSD) Digital Elevation Models (DEMs) and orthomosaicked images were generated by Pix4D professional photogrammetry software

Summary

Introduction

Glaciers are perennial features that temporarily store freshwater and they comprise only a fraction of the Cryosphere region. Numerous efforts are being made to observe and monitor glacier health using ground-based, aerial and spaceborne remote sensing platforms, e.g., [2,3,4,5,6,7]. Likewise, existing space borne remote sensing platforms have many limitations for collecting individual glacier level accurate data at high resolutions despite having numerous advantages for global scale glacier monitoring [6]. At this juncture, Unmanned Aerial Vehicles (UAV) as remote sensing platform, which can fly below the clouds has enormous potential to augment the sparse and discontinuous field observations by providing ultra-high-resolution images at relatively low costs. After using GCPs at ER2, the vertical (horizontal) RMSE was reduced to 1.49 m (0.04 m)

Objectives

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Conclusion