Jan Walstra

Royal Belgian Institute of Natural Sciences · Geological Survey of Belgium

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...

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...

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...

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...

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...

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...

Assessing Vertical Elevation Changes of Coastal Areas in Southern Chile to Improve The Understanding of Their Paleotsunami Sedimentary Records

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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).

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).

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...

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...

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...

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...