Jan Walstra

Jan Walstra
Royal Belgian Institute of Natural Sciences · Geological Survey of Belgium

PhD

About

32
Publications
24,875
Reads
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360
Citations
Additional affiliations
April 2007 - August 2011
Ghent University
Position
  • Researcher
April 2003 - March 2006
Loughborough University
Position
  • PhD Student

Publications

Publications (32)
Article
Full-text available
The coupled effects of climate change, sea-level rise, and land sinking in estuaries/alluvial plains prone to inundation and flooding mean that reliable estimation of land movements/subsidence is becoming more crucial. During the last few decades, land subsidence has been monitored by precise and continuous geodetic measurements either from space o...
Article
High-resolution seismic profiles, combined with the integration of published drilling data, provide a detailed paleoenvironmental history of Lake Yamanaka (Fuji Five Lakes, Japan). This study presents a detailed analysis of the different depositional stages of the area currently occupied by Lake Yamanaka (floodplain wetland, river and lake). From c...
Presentation
Full-text available
Societies rely on a secure, responsible and affordable supply of resources to meet their basic needs, in order to live life in a safe and healthy environment. The natural resources from the subsurface, i.e. groundwater, geo-energy and raw materials, represent essential elements in this provision. Safety from catastrophic events, such as those linke...
Article
Full-text available
Geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records. In this paper, we present a multi-proxy investigation of a coastal lowland site facing the Nankai-Suruga megathrust and appraise evidence for tsunamis and earthquake-triggered terrestrial mass...
Article
Full-text available
The time series of Synthetic Aperture Radar data acquired by four satellite missions (including ERS, Envisat, TerraSAR-X and Sentinel 1) were processed using Persistent Scatterer interferometric synthetic aperture radar (InSAR) techniques. The processed datasets provide a nearly continuous coverage from 1992 to 2017 over the Brussels Region (Belgiu...
Article
ERS, ENVISAT and TerraSAR-X Synthetic Aperture Radar scenes covering the time span 1992–2014 were processed using a Persistent Scatterer technique to study the ground movements in Merchtem (25 km NW of Brussels, Belgium). The processed datasets, covering three consecutive time intervals, reveal that the investigated area is affected by a global sub...
Poster
Assessing Vertical Elevation Changes of Coastal Areas in Southern Chile to Improve The Understanding of Their Paleotsunami Sedimentary Records
Article
Full-text available
This study aims to understand (mainly qualitatively) the long-term role of human impact on avulsion processes and the development of fluvial (mega-) fans in semi-arid environments. In this paper we refer to human impact as the direct influences of actions on the river's hydraulics (i.e. flow regulation, flow diversion and channel engineering). In f...
Article
Full-text available
Two of the primary external factors influencing the variability of major river systems, over river reach scales, are human activities and tectonics. Based on the rivers Karun and Dez in south-west Iran, this paper presents an analysis of the geomorphological responses of these major rivers to ancient human modifications and tectonics. Direct human...
Conference Paper
Full-text available
The Mesopotamian alluvial plain is dominated by large aggrading river systems that are prone to avulsion. Early civilizations depended on the position of rivers for their economic survival and were thus very sensitive to channel shifts that could be devastating. On the other hand, such shifts could also provide new opportunities for settlements and...
Conference Paper
Full-text available
Avulsion can be defined as the diversion of flow from an existing channel onto the floodplain (or the fan surface), eventually resulting in a new channel belt. It represents the response of a river system to a wide range of autogenic factors, such as river meandering and vertical accretion, and allogenic controls, such as tectonics, climate change...
Conference Paper
Full-text available
For many thousands of years the alluvial plains of Khuzestan (SW Iran) have been subject to intensive settlement and agriculture. Ancient societies depended on the position of major rivers for their economic survival and hence, there is ample evidence of human activities trying to control the distribution of water. Throughout the plains ancient irr...
Article
Full-text available
This study is concerned with the Late Holocene floodplain history of the Karkheh River in Lower Khuzestan, and in particular with the role of human action upon its channel shifts. The research was conducted in a multidisciplinary way, in which resources and approaches from different research fields were combined: (1) geomorphological mapping based...
Conference Paper
Full-text available
A complex of salt lakes, fringing the Mediterranean Sea between Larnaca and Cape Kiti, marks the Larnaca coastal plain in Eastern Cyprus. The ancient city of Hala Sultan Tekke is situated directly to the west of the main salt lake, and has been abandoned at the end of the Late Bronze Age (LBA; ~1200 BC). Several hypotheses circulate with respect to...
Article
Full-text available
This paper is concerned with the fundamental controls affecting the quality of data derived from historical aerial photographs typically used in geomorphological studies. A short review is provided of error sources introduced into the photogrammetric workflow. Data-sets from two case-studies provided a variety of source data and hence a good opport...
Article
Full-text available
This paper presents a multidisciplinary approach for studying the evolution of an alluvial fan system in Lower Khuzestan (SW Iran). The study draws on previously collected data from geological and archaeological field campaigns and new data derived from the interpretation of satellite imagery and historical textual sources. Three alluvial fans were...
Chapter
Full-text available
During the late Holocene, an avulsion-controlled Karun megafan developed in the Lower Khuzestan plain. Based on the interpretation of satellite data, at least three different Karun channels were detected. A chronological framework is provided by archaeological sites and textual sources. The presence of extensive irrigation systems highlights the im...
Conference Paper
Full-text available
Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2009. Remote sensing for the study of fluvial landscapes in Lower Khuzestan, SW Iran. RSPSoc 2009 Annual Conference, 8-11 September 2009, Leicester, UK, 9 pp. (ISBN 0-946226-34-2).
Conference Paper
Full-text available
Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2008. Remote sensing for recording past landscapes of the Mesopotamian alluvial plain. 1st International EARSeL Workshop on Advances in Remote Sensing for Archaeology and Cultural Heritage Management, 30 September – 4 October 2008, Rome, Italy, pp. 379-382 (ISBN 978-88-548-2030-2).
Article
Full-text available
This paper demonstrates the value of historical aerial photographs for assessing long-term landslide evolution. The study focussed on two case histories, the Mam Tor and East Pentwyn landslides. In both case histories the variety of data was explored, that could be derived relatively easily using an ordinary PC desktop, commercially available softw...
Article
Full-text available
A review is given of the techniques that are available to extract relevant information from multi-temporal aerial photographs for use in the monitoring stage of landslide assessments. It is shown that aerial photograph interpretation reveals qualitative information on surface characteristics, which is helpful in detecting landslide features and inf...
Thesis
Full-text available
Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy of Loughborough University. This study demonstrates the value of historical aerial photographs as a source for monitoring long-term landslide evolution, which can be unlocked by using appropriate photogrammetric methods. The understanding of land...
Article
Full-text available
A sequence of historical aerial photographs captures morphological change, which can only be unlocked by using appropriate photogrammetric methods. There are several challenges: initially it is necessary to trace and acquire suitable imagery in an appropriate format; typically there is a lack of precise photo-control available at the time of photog...

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Cited By

Projects

Projects (7)
Archived project
The GeoConnect³d project develops and tests a new methodological approach to prepare and disclose geological information for policy support and subsurface management. The improved approach uses two regional case studies – the Roer-to-Rhine region and the Pannonian Basin. These regional, cross-border case studies are chosen to be complementary and sufficiently different in geological setting and degree of implementation of subsurface exploitation and management, in order to maximize their pan-European relevance. A novel bottom-up approach introduces two concepts that increase the geological understanding of an area and are aimed at providing a coherent geological context for evaluating subsurface applications and resolving subsurface management issues. The first new concept is the structural framework as a means of joining existing models of different scale and resolution to clarify the importance of planar structures in a way that makes the geology understandable to stakeholders involved in subsurface management. The second concept is that of geomanifestations. These specific expressions of geological processes are important sources of information for improving geological understanding. The structural framework models annotated with geomanifestations allow the integration and evaluation of complex cross-thematic research. The two bottom-up regional case studies form the study material for a top-down, more generic evaluation of potentially interacting subsurface activities that allows revisiting and refining state-of-the-art methods. Valorisation of regional results at pan-European level is ensured by testing the methodologies in two smaller pilot areas in Germany and Ireland.
Project
Hydrogeological Modelling of the Campine area, Belgium