J. Rohn | Friedrich-Alexander-Universität Erlangen-Nürnberg (original) (raw)

Papers by J. Rohn

The impoundment of the Yangtze River in 2003 by the Three-Gorges-Dam (TGD) evokes ecological impa... more The impoundment of the Yangtze River in 2003 by the Three-Gorges-Dam (TGD) evokes ecological impacts alongside the Yangtze and its major tributaries that appear to be unforesseable in their dimension and dynamic. The scheduled water level elevation to 176 m in 2009 and the seasonal water level fluctuations at the TGD for the purpose of hydro power generation and flood control will still foster the typical aftermaths such as slope instability, mass movements, soil erosion, the expansion of infrastructure and land reclamation for subsistence agriculture and cash crops distant to the inundated area. Together, geoscientists from China and Germany try to develop an integrated risk assessment system for landslides, soil erosion, diffuse sediment and matter fluxes into the reservoir and land-use vulnerability. Since April 2008 the research activities take place within the Sino-German YANGTZE project funded by the German BMBF and initiated by the German Research Centre Juelich. The project proceeds in close collaboration with the Ministry of Land and Resources of the People's Republic of China (MRL). In four subprojects located at the universities of Erlangen, Giessen, Potsdam and Tuebingen main focus lies on the analysis and assessment of the mechanisms and trigger of landslides, the mechanisms of soil erosion for different landscape morphologies and soil associations and the multi-temporal land-use classification and land-use dynamic on the meso-scale. The research area is the highly dynamic and mountainous Xiangxi catchment (3.100 km 2 ) close to the TGD. Using multi-level approaches by means of GIS, field investigations and remote sensing the Yangtze project aims to assess the spatial and temporal varying risk potential of soil erosion and the landslide susceptibility and risk for the infrastructure, people and agriculture. Finally, high-resolution risk potential maps will serve as a base for decision making. In close collaboration with our Chinese partner projects (China University of Geosciences, Wuhan; Institute of Soil Sciences, CAS, Nanjing; Aero Geophysical Survey and Remote Sensing for Land and Resources, Beijing) we seek to enhance our understanding of the ecological consequences of large dam projects.

Natural Hazards, 2015

ABSTRACT The 2005 Kashmir earthquake (Mw 7.6) generated widespread mass movements in the Northeas... more ABSTRACT The 2005 Kashmir earthquake (Mw 7.6) generated widespread mass movements in the Northeast Himalayas of Pakistan. The mass movements were mainly catastrophic rock avalanches, rockslides, rockfalls and debris falls, ranging in volume from a few hundred cubic meters to hundreds of million cubic meters. Data of 103 mass movement events were collected during field surveys to characterize each event. The mass movements and their travel distances were analyzed, using empirical models, widely adopted in the literature. The empirical approaches were used to analyze the relationships between geometrical parameters like volume, Fahrbo¨schung angle, fall height, surface area, travel path and travel distance. The mobility of mass movements was expressed as the ratio between the height of fall and travel distance as function of volume. The volume was estimated by multiplying the deposit area by average thickness. The Fahrbo¨schung angle showed a decreasing tendency with increasing mass movement volume. In addition, the Fahrbo¨schung angle of mass movements with small volumes was more variable. A strongly correlated linear trend exists between the height of fall and travel distance for all types of the mass movement. Moreover, a weak correlation was found between unconfined and partly confined travel path. The empirical results of the 2005 Kashmir earthquake data are consistent with the previously published data from other parts of the world.

ABSTRACT The Kashmir earthquake 2005 (Mw 7.6) generated thousands of mass movements through out a... more ABSTRACT The Kashmir earthquake 2005 (Mw 7.6) generated thousands of mass movements through out an area of more than 7,500 km2 in Northern Pakistan. The data of forty selected mass movement events ranging from 10 thousand m3 up to 100 million m3 volume have been gathered for a run-out analysis. The study is based on field data, like movement type, Fahrböschung, shadow angle, material, slope angle and volume. The relationship between the height of fall and run-out distance were studied for mountain falls, rock falls and debris falls. The mobility of mass movements is expressed as the ratio between the height of fall (H) and run-out distance (L) as function of volume and height of fall. The volume (V) is generally estimated by multiplying the deposit area (A) by an estimation of average thickness (D). The travel distance of selected events has been analyzed by using the main basic empirical models existing in the literature. The data show the differences in run-out distance and mass movement mobility among different types of mass movements. The linear regression analysis has been performed own data and compared with data published other regions in the world. The results show that data is consistent with that of previous research. The study provides a significant set of data for the empirical analysis that may be used for hazard and risk evaluation.

In the northern part of Pakistan, thousands of landslides were triggered during the 2005 Kashmir ... more In the northern part of Pakistan, thousands of landslides were triggered during the 2005 Kashmir earthquake. On 24 March 2014, the Karli landslide, located in district Hattian, about 65 km southeast of capital city of Muzaffarabad, Pakistan was reactivated due to heavy rain fall. Simultaneously, another slide adjacent to the main slide was triggered that transformed rapidly into earth flow. In order to investigate the Karli landslides, field investigations were carried out two weeks after the reactivation of Karli landslide. In addition, SPOT and Google imageries were used to delineate the affected area. DEM was used to study the topographic characteristics of the area. The landslide affected area measuring about 1000 m long and 800 m wide damaged about 156 houses and displaced 900 inhabitants. In addition, on 24 March 2014 earth flow destroyed 3 houses completely and many others are under potential threats. On the basis of field observation and satellite data it is inferred that the Karli landslide was outcome of breach out of Karli lake in February 2010. The landslide movement initiated after falling down of water level of the Karli lake. The landslide hazard assessment indicates that the affected area is under continuous threat of landslide due to the effects of drawdown of Karli lake. Therefore, the inhabitants of the Karali area are under potential risk and need to be relocated to the safer places. [Muhammad Basharat, Joachim Rohn, Muhammad Rustam Khan. Effect of drawdown of Karli Lake: A Case Study of Karli landslide hazard in District Hattian, Northeast Himalayas of Pakistan. Life Sci J 2014;11(9):610-616]. (ISSN:1097-8135). http://www.lifesciencesite.com. 98

Geomorphology, 2014

ABSTRACT Distribution of the mass movements triggered by the 2005 Kashmir earthquake was analysed... more ABSTRACT Distribution of the mass movements triggered by the 2005 Kashmir earthquake was analysed in the vicinity of Jhelum Valley, Neelum Valley, and Muzaffarabad in the Northeast Himalayas of Pakistan. Mass movements were mapped using SPOT satellite imagery and field investigations. Geographic information systems (GIS) were used to analyse the relations of the distribution of these mass movements using various parameters, such as distance from an earthquake source (epicentre and fault), topographic parameters (slope steepness, slope aspect, and elevation) and geological units. The results of the analysis indicate that the mass movement concentration decreases with increased distance from the earthquake epicentre and the reactivated Muzaffarabad Fault. The maximum concentration of mass movements is near the epicentre and a fault. A significant occurrence and concentration of mass movements were evident at slope angles between 31–40°. The preferred orientations of the mass movements were in southerly directions. The concentrations of mass movements differ substantially among various geological units. Mass movements are widely distributed in the Miocene Murree Formation, whereas the concentration of mass movements is higher in the Cambrian Muzaffarabad Formation. The median mass movement concentration inflicted by the epicentre and the Muzaffarabad Fault exhibited no significant differences (KS = 0.505; p = 0.961). The results of the PCA reveal that the largest variance in mass movement concentration is attributed to the distance from the epicentre and the Muzaffarabad Fault. The findings suggest that the mass movement concentration is primarily dependent on the distance from the earthquake source. In addition, the topographic parameters and geological units played subordinate roles in the distribution of mass movements.

Within the framework of landslide hazard analysis the knowledge of the existence and location of ... more Within the framework of landslide hazard analysis the knowledge of the existence and location of hazard zones is an essential prerequisite. Besides the well-known deterministic and statistical methods, the use of artificial neural nets (ANN) is a very promising approach for susceptibility mapping. The advantage provided by neural nets is their flexibility and their ability to handle non-linearities. The problem resulting from this is the control of the model complexity. An interesting approach to control model complexity as well as improving the overall performance of the ANN is the application of the multi task learning (MTL) concept. The tests, carried out to identify landslides in test areas in the Eastern Alps, reveal that the best nets have clas-sified up to 89% of the areas correctly. It is of particular interest that ANN are able to identify different types of mass movements with one and the same net.

this paper, Sherbrooke and Patrikalakis(1993) use Bernstein expansion. Sequences of bounding boxe... more this paper, Sherbrooke and Patrikalakis(1993) use Bernstein expansion. Sequences of bounding boxes for the solutionsto the polynomial system are generated by two different approaches: the firstmethod projects control polyhedra onto a set of coordinate planes and the secondexploits linear programming. But no use of the relationship between theBernstein coefficients on neighbouring subboxes, cf. Subsection 2.2 below, ismade and no existence

The Sino-German YANGTZE project aims to study the impact of the Three Gorges Dam (P. R. China) on... more The Sino-German YANGTZE project aims to study the impact of the Three Gorges Dam (P. R. China) on the environment in the Three Gorges Reservoir area. The main focus lies on the four research fields water quality, vegetation, slope stability and atmosphere. The research activities of the four research fields are coordinated by Research Centre Jülich. Within this YANGTZE project

Environmental Earth Sciences, 2010

Landslides located beside reservoirs tend to be unstable or are characterized by large deformatio... more Landslides located beside reservoirs tend to be unstable or are characterized by large deformation during the drawdown process. This has been accepted by many experts. In this paper, we use Qiaotou Landslide, which is located beside the Three Gorges Reservoir (TGR), as a typical case study to investigate and predict the deformation mechanism during the drawdown process of TGR in detail. According to field investigation, the landslide mass is mainly composed of thick, loose silt and clay mixed with fragments of rock. Bedrock is mainly composed of silty sandstone. Field and laboratory tests indicate that the landslide mass has a high permeability coefficient. If the water level declines fast, intense seepage force may result. Based on these data, we establish a three-dimensional geological model of Qiaotou Landslide by FLAC3D and perform a numerical simulation using the saturated–unsaturated fluid–solid coupling theory. For the simulation, we assume that the drawdown from 175 to 145 m takes place with a speed of 25 cm/day, which is based on the extreme water level regulation program of TGR. The simulation shows that this causes a significant deformation in the landslide mass and that the maximum displacement within the landslide is 24.2 cm. During the drawdown process, the maximum displacement zone is shifting from the upper part of the landslide where bedrock surface is steeper and thickness of loose deposits is less to the middle part of the landslide where bedrock surface is less steep and thickness of loose deposits is higher. The deformation mechanism indicates that in the early stage of the drawdown the deformation of the landslide mass is mainly caused by seepage and in the later stage mainly by consolidation.

ABSTRACT The recession of alpine glaciers since the end of the Little Ice Age (LIA), which has be... more ABSTRACT The recession of alpine glaciers since the end of the Little Ice Age (LIA), which has been accelerating in the past decades, has exposed stores of glacial sediment to the activity of paraglacial processes. Following deglaciation, an increase in sediment (re-)mobilisation within and export from proglacial areas (i.e. the area within the LIA terminal moraines) can be expected which may affect the downstream channel network, including potential threats to settlements and infrastructure. Slope aquatic and fluvial processes and mass movements (including debris flows, slides and falls) within the proglacial area have received comparatively little attention in previous studies of the (pro)glacial sediment budget that have been focused mainly on suspended and bedload sediment transport in proglacial streams. Hence, there is a need for research concerning the relative importance of non-glacial and glacial contribution to the sediment budget. Additionally, the connectivity of proglacial sediment cascades needs to be assessed in order to address the consequences of enhanced geomorphic activity on sediment export from the proglacial system. The PROSA joint project (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) is determined to tackle these problems through a quantification of sediment fluxes effected by the aforementioned geomorphic processes within the forefield of the Gepatschferner glacier (Central Alps, Austria). In this paper, we present an outline of ongoing and planned research activities of the interdisciplinary PROSA project group which encompasses the expertise of geomorphologists, geologists, glaciologists and geodesists. On the local scale, field measurements and high-resolution digital elevation models from multi-epoch ground-based LiDAR data (> 40 scan positions) are combined to map and quantify sediment (re)mobilisation, erosion and deposition. Measurement plots are arranged in chronosequences in order to estimate the influence of time since deglaciation on morphodynamics. The catchment scale sediment budget will be established by multi-epoch high-resolution aerial LiDAR data (flight campains in July and October 2012) and by upscaling of local findings using geomorphological models including the appraisal of slope-channel coupling. Fluvial sediment transport is measured in the main proglacial rivers at 4 gauging stations. A combined dam and power plant directly downstream of the catchment outlet provides a good opportunity to close the sediment budget through measurements of delta aggradation when the reservoir level is artificially lowered. see also PROSA-related EGU2013 abstracts: Vehling et al. 2013 Landslides and rock fall processes in the proglacial area of the Gepatsch glacier, Tyrol, Austria - Quantitative assessment of controlling factors and process rates. Geophysical Research Abstracts Vol. 15, EGU2013-5323-2 Neugirg et al. 2013 Quantification of debris-flow erosion rates by using high-resolution multitemporal terrestrial and airborne LiDAR data in the Kaunertal/Eastern Alps, Austria. Geophysical Research Abstracts Vol. 15, EGU2013-7330 Hilger et al. 2013 Paraglacial adjustment of Little Ice Ace moraine slopes at the Gepatschferner glacier, Ötztal Alps, Austria. Geophysical Research Abstracts Vol. 15, EGU2013-7551 Rohn et al. 2013 Mass balance study of gravitational mass movements in proglacial systems. Geophysical Research Abstracts Vol. 15, EGU2013-8557 Stocker-Waldhuber et al. 2013 Overview of glacial and subglacial mass exchange measurements on Gepatschferner (Ötztal Alps, Austria). Geophysical Research Abstracts Vol. 15, EGU2013-9444 Briese et al 2013 Integration of multi-temporal airborne and terrestrial laser scanning data for the analysis and modelling of proglacial geomorphodynamic processes. Geophysical Research Abstracts Vol. 15, EGU2013-9479 Morche et al. 2013 On the hydrology and fluvial sediment transport of the proglacial river Riffler Bach (Weißseeferner, Ötztal Alps, Tyrol). Geophysical Research Abstracts Vol. 15, EGU2013-9785 Baewert et al. 2013 Detecting surface changes of glaciofluvial deposits in an alpine proglacial area using terrestrial laser scanning. Geophysical Research Abstracts Vol. 15, EGU2013-9925

We present a sufficient regularity condition for interval matrices which generalizes two previous... more We present a sufficient regularity condition for interval matrices which generalizes two previously known ones. It is formulated in terms of positive definiteness of a certain point matrix, and can also be used for checking positive definiteness of interval matrices. Comparing it with Beeck's strong regularity condition, we show by counterexamples that none of the two conditions is more general than the other one. Above: logo of interval computations and related areas (depiction of the solution set of the system [2, 4]x 1 + [−2, 1]x 2 = [−2, 2], [−1, 2]x 1 + [2, 4]x 2 = [−2, 2] (Barth and Nuding [1])).

Interval matrix norms induced by point matrix norms are introduced in the space of interval matri... more Interval matrix norms induced by point matrix norms are introduced in the space of interval matrices. It is shown that evaluating the interval matrix norm induced by a point matrix norm · p is exponential (probably NP-hard) for p = 2 and requires computation of only one point matrix norm for p ∈ {1, ∞, (1, ∞), F }. . 4 Above: logo of interval computations and related areas (depiction of the solution set of the system [2, 4]x 1 + [−2, 1]x 2 = [−2, 2], [−1, 2]x 1 + [2, 4]x 2 = [−2, 2] (Barth and Nuding [3])).

Journal of Earth Science, 2012

The Kashmir earthquake 2005 (magnitude M W 7.6) triggered thousands of mass movements in northern... more The Kashmir earthquake 2005 (magnitude M W 7.6) triggered thousands of mass movements in northern Pakistan. These mass movements were mainly rock falls, debris falls, rockslides and rock avalanches. The mass movements vary in size from a few hundred cubic meters up to about 100 million cubic meters estimated for the Hattian Bala rock avalanche, the biggest one associated with this earthquake. This mass movement, which moved in southeastern direction, created two natural dams on the valley bottom and blocked the water ways of the Karli and Tung tributaries of the Jhelum River. Topographic, lithologic and structural information were used to investigate the Hattian Bala rock avalanche. Geotechnical and structural maps were prepared to understand relationship between geology and structure of Hattian Bala rock avalanche. The geometry and failure mode of this rock avalanche are controlled by southeast plunging synclinal structures, lithology, a bedding parallel slip surface and a pre-existing old rockslide. The structural map shows that the mass movement failure was due to Danna and Dandbeh synclinal structures plunging southeast on the hanging wall block of the reactivated Muzaffarabad fault. The slip surface of the mass movement followed the bedding planes along mudstone, claystone and sandstone surfaces. The mass movement perfectly followed the pre-existing synclinal morphology of the Danna and Dandbeh synclines. KEY WORDS: Kashmir earthquake 2005, mass movement, rock avalanche, Muzaffarabad fault, northern Pakistan.

Journal of Mountain Science, 2014

ABSTRACT The SPOT image analysis in Muzaffarabad Azad Kashmir, northwest Himalayas, Pakistan reve... more ABSTRACT The SPOT image analysis in Muzaffarabad Azad Kashmir, northwest Himalayas, Pakistan reveals that the Kashmir earthquake 2005 triggered a number of coseismic mass movements along the hanging wall block of the Muzaffarabad Fault. The Neelidandi and Langarpura rock falls have been identified as two major reactivated mass movements with an estimated volume of 3.1 x 10(6) m(3) and 5.76 x 10(6) m(3), respectively. The Neelidandi and Langarpura mass movements were initiated during earthquake in the direction of northwest-southeast extension and northeast-southwest directed thrusting, respectively. The Neelidandi rock fall occurred in sheared cherty dolomites and limestones of the Cambrian Muzaffarabad Formation, whereas the Langarpura rock fall occurred in alternating clays, shales, claystones, siltstones and sandstones of the Miocene Murree Formation. These rock units along the fault are highly fractured and jointed. The geotechnical maps and geological longitudinal profiles show the relationship between the geometrical characteristics and mechanism of these mass movements. Their characteristics were analyzed according to the role of topographic, seismic, geological and tectonic factors. The steep topography, sheared rocks, lithology, coseismic uplift and strong ground shaking of the hanging wall block along Muzaffarabad Fault facilitated the gravity collapse of these mass movements.

Optimization Letters, 2014

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Linear and Multilinear Algebra, 1995

It is proved that two previously known sufficient conditions for regularity of interval matrices ... more It is proved that two previously known sufficient conditions for regularity of interval matrices are equivalent in the sense that they cover the same class of interval matrices.

Linear Algebra and its Applications, 1994

We study how much perturbation 6A in a real matrix A is allowed for the i th real eigenvector not... more We study how much perturbation 6A in a real matrix A is allowed for the i th real eigenvector not to change sign.

Environmental Geology, 2005