Analysis of the influence of tectonics on the evolution of valley networks based on Srtm Dem, Jemma River basin, Ethiopia

The Ethiopian Highlands are a good example of a high plateau landscape formed by a combination of tectonic uplift and episodic volcanism. Deeply incised gorges indicate active fluvial erosion, which leads to instabilities of over-steepened slopes. In this study we focus on the Jemma River basin, which is a left bank tributary of the Abay - Blue Nile in order to assess the influence of neotectonics on the evolution of its river and valley network. Tectonic lineaments, shape of valley networks, direction of river courses and intensity of fluvial erosion were compared in six subregions, which were delineate beforehand by means of morphometric analysis. The influence of tectonics on the valley network is low in the older deep and wide canyons and on the high plateau covered with Tertiary lava flows, whilst in the younger upper part of the canyons it is high. Furthermore, the coincidence of the valley network with the tectonic lineaments differs in the subregions. The direction of the fluvial erosion along the main tectonic zones (NE-SW) made it possible for backward erosion to reach far distant areas in the east. This tectonic zone also separates older areas in the west from the youngest landscape evolution subregions in the east, next to the Rift Valley

An approach to derive snow lines from MODIS data on the Tibetan Plateau,its analysis and climatic forcings

Abstract HKT-ISTP 2013 B

Exploration of a periodic GLOF in Halji, West Nepal using modeling and remote sensing

Abstract HKT-ISTP 2013 B

Geomorphological processes, forms and features in the surroundings of the Melka Kunture Palaeolithic site, Ethiopia

The landscape of the surroundings of the Melka Kunture prehistoric site, Upper Awash Basin, Ethiopia, were studied intensively in the last decades. Nonetheless, the area was mainly characterized under a stratigraphic/geological and archaeological point of view. However, a detailed geomorphological map is still lacking. Hence, in this study, we identify, map and visualize geomorphological forms and processes. The morphology of the forms, as well as the related processes, were remotely sensed with available high-resolution airborne and satellite sources and calibrated and validated through extensive field work conducted in 2013 and 2014. Furthermore, we integrated multispectral satellite imagery to classify areas affected by intensive erosion processes and/or anthropic activities. The Main Map at 1:15,000 scale reveals structural landforms as well as intensive water-related degradation processes in the Upper Awash Basin. Moreover, the map is available as an interactive WebGIS application providing further information and detail (www.roceeh.net/ethiopia_geomorphological_map/)

Remote sensing for characterisation and kinematic analysis of large slope failures : Debre Sina landslide, Main Ethiopian Rift Escarpment

This study was carried out in the framework of the German Science Foundation (DFG) project “Integrated assessment of geomorphological process dynamics on different spatio-temporal scales in the Ethiopian Highlands using remote sensing and advanced modelling approaches” (HO1840/11-1) and the Czech Science Foundation (GAČR) project “Mass wasting and erosion as an indicator of morphotectonic activity in the Ethiopian Highlands based on remote sensing approaches” (P209/12/J068). The ALOS/PRISM data were provided by the ESA in the framework of the project ID13160. The aerial photographs were provided by the Ethiopian Mapping Agency. We would like to thank the Gesellschaft für Erd- und Völkerkunde, Stuttgart, Germany for supporting the field campaign in 2015.Frequently occurring landslides in Ethiopia endanger rapidly expanding settlements and infrastructure. We investigated a large landslide on the western escarpment of the Main Ethiopian Rift close to Debre Sina. To understand the extent and amplitude of the movements, we derived vectors of horizontal displacements by feature matching of very high resolution satellite images (VHR). The major movements occurred in two phases, after the rainy seasons in 2005 and 2006 reaching magnitudes of 48 ± 10.1 m and 114 ± 7.2 m, respectively. The results for the first phase were supported by amplitude tracking using two Envisat/ASAR scenes from the 31 July 2004 and the 29 October 2005. Surface changes in vertical direction were analyzed by subtraction of a pre-event digital elevation model (DEM) from aerial photographs and post-event DEM from ALOS/PRISM triplet data. Furthermore, we derived elevation changes using satellite laser altimetry measurement acquired by the ICESat satellite. These analyses allowed us to delineate the main landslide, which covers an area of 6.5 km2, shallow landslides surrounding the main landslide body that increased the area to 8.5 km2, and the stable area in the lower part of the slope. We assume that the main triggering factor for such a large landslide was precipitation cumulated over several months and we suspect that the slope failure will progress towards the foot of the slope.Publisher PDFPeer reviewe

Overall recession and mass budget of Gangotri Glacier, Garhwal Himalayas, from 1965 to 2015 using remote sensing data

Thinning rates for the debris-covered Gangotri Glacier and its tributary glaciers during the period 1968-2014, length variation and area vacated at the snout from 1965 to 2015, and seasonal variation of ice-surface velocity for the last two decades have been investigated in this study. It was found that the mass loss of Gangotri and its tributary glaciers was slightly less than those reported for other debris-covered glaciers in the Himalayan regions. The average velocity during 2006-14 decreased by ~6.7% as compared with that during 1993-2006. The debris-covered area of the main trunk of Gangotri Glacier increased significantly from 1965 until 2015 with the maximum rate of increase (0.8 ± 0.2 km2 a-1) during 2006-15. The retreat (~9.0 ± 3.5 m a-1) was less in recent years (2006-2015) but the down-wasting (0.34 ± 0.2 m a-1) in the same period (2006-2014) was higher than that (0.20 ± 0.1 m a-1) during 1968-2006. The study reinforced the established fact that the glacier length change is a delayed response to climate change and, in addition, is affected by debris cover, whereas glacier mass balance is a more direct and immediate response. Therefore, it is recommended to study the glacier mass balance and not only the glacier extent, to conclude about a glacier's response to climate change.Publisher PDFPeer reviewe

Advances in the process-related understanding of atmosphere-cryosphere-hydrosphere couplings on the Tibetan Plateau

Abstract HKT-ISTP 2013 B