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Jan Walstra

Royal Belgian Institute of Natural Sciences, Geological Survey of Belgium, Faculty Member

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Address: Geological Survey of Belgium
Royal Belgian Institute of Naturalsciences
Jennerstraat 13
B-1000 Brussels
Belgium

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Vanessa Heyvaert

Royal Belgian Institute of Natural Sciences

Peter Verkinderen

Aga Khan University

Cultural Heritage Agency of the Netherlands

Benjamin T Pennington

University of Southampton

University of Al-Qadisiyah

Jennifer R Pournelle

University of South Carolina

Northwestern University

Università degli Studi di Milano - State University of Milan (Italy)

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Papers by Jan Walstra

Remote sensing for recording past landscapes of the Mesopotamian alluvial plain

by Jan Walstra, Peter Verkinderen, and Vanessa Heyvaert

Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2008. Remote sensing for recording past landsca... more 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).

The role of rivers in ancient societies, or how man transformed the alluvial landscapes of Khuzestan (SW Iran)

For many thousands of years the alluvial plains of Khuzestan (SW Iran) have been subject to inten... more 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 irrigation and settlement patterns are visible, although traces are rapidly disappearing due to expanding modern land use. Aim of this study is to unlock and integrate the rich information on landscape and archaeology, which only survives through the available historical imagery and some limited archaeological surveys. A GIS-based geomorphological mapping procedure was developed, using a variety of imagery, including historical aerial photographs, CORONA, Landsat and SPOT images. In addition, supported by the evidence from previous geological field surveys, archaeological elements were identified, mapped and included in a GIS database. The re...

Historical aerial photographs and digital photogrammetry for landslide assessment

Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Phil... more 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 landslide mechanisms requires extensive data records; a literature review identified quantitative data on surface movements as a key element for their analysis. It is generally acknowledged that, owing to the flexibility and high degree of automation of modern digital photogrammetric techniques, it is possible to derive detailed quantitative data from aerial photographs. In spite of the relative ease of such techniques, there is only scarce research available on data quality that can be achieved using commonly available material, hence the motivation of this study. In two landslide case-studies (the Mam Tor and East Pentwyn landslides) the dif...

Remote sensing for the study of fluvial landscapes in Lower Khuzestan, SW Iran

Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2009. Remote sensing for the study of fluvial l... more

Studying the driving forces of landscape change in the surroundings of the Late Bronze Age harbor town Halla Sultan Tekke, Cyprus. In: Geophysical Research Abstracts, vol. 14, pp. EGU2012-9413, European Geosciences Union

A complex of salt lakes, fringing the Mediterranean Sea between Larnaca and Cape Kiti, marks the ... more 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 the LBA societal collapse in the Eastern Mediterranean: from the invasion by the 'sea people', climate change to an earthquake or even a tsunami catastrophe. Nearby the archaeological site, the salt lake is protected from the Mediterranean Sea by a Pleistocene sandstone barrier.A second middle to late Holocene ridge separates the salt lakes completely from the Mediterranean Sea. Three faults, trending nearly perpendicular to the present-day coastline, are identified near the salt lakes. Human-environmental interactions that may have led to the abandonment of the ancient city of Hala Sultan Tekke are investigated by studying the se...

Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran

Long-term interactions between man and the fluvial environment-case of the Diyala alluvial fan, Iraq

The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, T... more The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013. Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes.

A History of Aerial Photography and Archaeology: Mata Hari's Glass Eye and Other Stories. By M. Barber. English Heritage, Swindon, UK, 2011. ISBN 978 1 848020 36 8. 194 mm × 252 mm. 304 pages. Price £25·00 hardback

The Photogrammetric Record, 2013

Human impact on alluvial fan development: can human niche construction provide a conceptual framework for long-term landscape evolution?

by Jan Walstra and Vanessa Heyvaert

Use of digital photogrammetry for the study of unstable slopes in urban areas: Case study of the El Biar landslide, Algiers

Recent developments in remote sensing techniques provide powerful tools for geomorphological stud... more Recent developments in remote sensing techniques provide powerful tools for geomorphological studies. The geometric and kinematic characterization of landslides are key factors in understanding the mechanisms of movement. The purpose of this publication is to show the potential of digital photogrammetry in the spatiotemporal study of landslides in urban areas. The case study focuses on the landslide of El Biar in Algiers. Comparison of digital elevation models generated following an established methodology shows the morphological evolution of the site. Orthophotos are used to measure surface displacements. The analysis of horizontal displacements between 1995 and 2007 shows that the landslide of El Biar can be divided into two zones: a peripheral zone moving at an average speed of about 5 cm per year and a central zone moving at an average speed of about 10 cm per year. Comparing the results with those obtained by traditional survey methods shows a remarkable consistency, thus validating the techniques used. This study demonstrates that digital photogrammetry, when combined with geological and geotechnical data, can improve the characterization and understanding of landslides mechanisms, and thus help defining mitigation solutions.

Geoarchaeological Research in Lower Khuzestan: State of The Art

The role of human interference on the channel shifting of the Karkheh River in the Lower Khuzestan plain (Mesopotamia, SW Iran

Quaternary International, 2012

This study is concerned with the Late Holocene floodplain history of the Karkheh River in Lower K... more 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 on the interpretation of Landsat and CORONA satellite imagery, (2) analyses of geological sequences, including the identification of sedimentary facies and radiocarbon dating of organic material, (3) an archaeological field survey of ancient settlements, and (4) consultation of historical documents, mainly Arabic texts from the 9th–14th century and European travel literature from the 16th-early 20th century. Three main channel belts of the Karkheh were identified (labelled Kh1, Kh2 and Kh3), corresponding to successive stages in the evolution of the floodplain. Two river shifts are documented in the datasets, both taking place within the last 2000 years. The first avulsion regards a shift from channel belt Kh1, once a tributary of the Karun, to the straight river bed of Kh2, taking place at least after 1240–1310 cal BP/710–640 AD. The second avulsion, from Kh2 to Kh3, is clearly documented in historical sources and happened in a single night event in the year 1837/113 cal BP. Reactivation of the Kh2 river bed and its irrigation canals can be attributed to the recent construction of an artificial canal bypassing the second avulsion point. Both river shifts were strongly influenced by human interference, whereby an artificial irrigation canal took over the entire river flow from the main channel belt. Most likely, a combination of human-induced factors, such as weakening of the river levees, high sedimentation rates and disadvantageous channel gradients, led to a situation prone to avulsion.

Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran

Geodinamica Acta, 2010

This paper presents a multidisciplinary approach for studying the evolution of an alluvial fan sy... more 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 identified, successively deposited by the Jarrahi river in progressively downstream/westward direction. Judging from archaeological and historical evidence, the successive phases appear to coincide with a relocation of settlement and irrigation activities. The distributary system of the present-day fan developed over a period of less than four centuries. It is suggested that management of levee breaks by man played a key role in such rapid fan development and in maintaining extremely low gradients. Judging from the extensive patterns of ancient irrigation canals, human activity also played an important role in the formation of the earlier fans.

Mapping Late Holocene Landscape Evolution and Human Impact – A Case Study from Lower Khuzestan (SW Iran

Recent advances in the fields of remote sensing and GIS provide the techniques to establish a fir... more Recent advances in the fields of remote sensing and GIS provide the techniques to establish a firm geomorphological framework to the historical and archaeological studies in the Mesopotamian region. This study presents a practical approach for the mapping of the semi-arid, alluvial landscapes of Lower Khuzestan. As elsewhere in Mesopotamia, the landscapes here are strongly affected by anthropogenic processes, most evidently expressed by widespread irrigation patterns. The image interpretation key and map legend are therefore designed explicitly to reflect these typical alluvial and human-induced landforms. The working procedure is based on easily accessible and inexpensive source material, notably Landsat and CORONA imagery, SRTM elevation data and readily available topographical maps, and was successfully applied in a case study on the evolution of the Jarrahi River. The resulting map, together with information from other disciplines, provided insights into the complex landscape evolution of the study area and a useful base for further research.

Reconstructing landscape evolution in the Lower Khuzestan plain (SW Iran): integrating imagery, historical and sedimentary archives

Landscapes Through The Lens: Aerial Photographs and Historic Environment, 2010

or from our website www.oxbowbooks.com Front cover: Étang de Montady, Languedoc-Roussillon in sou... more or from our website www.oxbowbooks.com Front cover: Étang de Montady, Languedoc-Roussillon in southern France. A remarkable pattern of fi eld boundaries created in the 13th century on a reclaimed lake photographed on 6 August 1944. Drains converge on the circle which lies at the centre of the former lake, with water then transported out of the shallow basin through a tunnel 1.3km long under the Hill of Malpas. TARA_MAPRW_106G_1960_4175, © Crown Copyright, RCAHMS Back cover: Erbil, the capital of Iraqi Kurdistan, is a claimant to the title of oldest continuously inhabited settlement in the world. The modern city is still dominated by the ancient tell, recorded here on 22 October 1948 when still a relatively small town. RAF_13A/131_3144,

Historical aerial photographs for landslide assessment: two case histories

Quarterly Journal of Engineering Geology and Hydrogeology, 2007

This paper demonstrates the value of historical aerial photographs for assessing long-term landsl... more This paper demonstrates the value of historical aerial photographs for assessing long-term landslide evolution. The study focused on two case histories, the Mam Tor and East Pentwyn landslides. In both case histories we explored the variety of data that could be derived relatively easily using an ordinary PC desktop, commercially available software and commonly available photographic material. The techniques to unlock qualitative and quantitative data captured in the photographic archive were based on the principles of aerial photo-interpretation and photogrammetry. The products created comprised geomorphological maps, automatically derived digital elevation models (DEMs), displacement vectors and animations. The measured horizontal displacements of the Mam Tor landslide ranged from 0.09 to 0.74 m a−1 between 1953 and 1999, which was verified by independent survey data. Moreover, the observed displacement patterns were consistent with photo-interpreted geomorphological information. The photogrammetric measurements from the East Pentwyn landslide (horizontal displacements up to 6 m a−1 between 1971 and 1973) also showed a striking resemblance to independent data. In both case histories, the vertical accuracy was insufficient for detecting significant elevation changes. Nevertheless, DEMs proved to be a powerful tool for visualization. Overall, the results in this study validated the techniques used and strongly encourage the use of historical photographic material in landslide studies.

Evaluation of the controls affecting the quality of spatial data derived from historical aerial photographs

Earth Surface Processes and Landforms, 2011

This paper is concerned with the fundamental controls affecting the quality of data derived from ... more 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 opportunity to evaluate the influence of the quality of archival material on the accuracy of coordinated points. Based on the statistical weights assigned to the measurements, precision of the data was estimated a priori, while residuals of independent checkpoints provided an a posteriori measure of data accuracy. Systematic discrepancies between the two values indicated that the routinely used stochastic model was incorrect and overoptimistic. Optimized weighting factors appeared significantly larger than previously used (and accepted) values. A test of repeat measurements explained the large uncertainties associated with the use of natural objects for ground control. This showed that the random errors not only appeared to be much larger than values accepted for appropriately controlled and targeted photogrammetric networks, but also small undetected gross errors were induced through the ‘misidentification’ of points. It is suggested that the effects of such ‘misidentifications’ should be reflected in the stochastic model through selection of more realistic weighting factors of both image and ground measurements. Using the optimized weighting factors, the accuracy of derived data can now be more truly estimated, allowing the suitability of the imagery to be judged before purchase and processing.

Aerial photography and digital photogrammetry for landslide monitoring

Geological Society, London, Special Publications, 2007

A review is given of the techniques that are available to extract relevant information from multi... more 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 inferring the mechanisms involved. Photogrammetrically derived products can be used to quantify these processes, providing distinctive advantages. Comparison of digital elevation models (DEMs) from different times provides detailed information on changes in surface topography, whereas orthophotos can be used to measure horizontal displacements. The various factors influencing the quality of the products are also identified. Examples from a case study on the Mam Tor landslide are used to illustrate the benefits of the different approaches.

Quantifying landform change

Applications of 3D Measurement from Images, 2007

Extracting landslide movements from historical aerial photographs

Landslides: Evaluation and Stabilization, 2004

Recent developments in digital photogrammetry allow high resolution quantitative data to be extra... more Recent developments in digital photogrammetry allow high resolution quantitative data to be extracted. This paper will present the digital techniques used to extract morphological change from a time series of historical aerial photographs. Initial results from a case-study at Mam Tor (Derbyshire, UK) show the potential of the methods to quantify past landslide movements. Photographs from 1958 and 1971 were used to create digital elevation models and orthophotographs and used for the analysis. Due to the poor geometry of one set of images the vertical accuracy was rather low. But, in spite of the low resolution, significant horizontal movements could be detected and these were consistent with observations from other researchers. Incorporation of additional epochs will extend the series and improve accuracies. This research is part of an ongoing project to model the response of landslides to future climate change.

Remote sensing for recording past landscapes of the Mesopotamian alluvial plain

by Jan Walstra, Peter Verkinderen, and Vanessa Heyvaert

Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2008. Remote sensing for recording past landsca... more 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).

The role of rivers in ancient societies, or how man transformed the alluvial landscapes of Khuzestan (SW Iran)

For many thousands of years the alluvial plains of Khuzestan (SW Iran) have been subject to inten... more 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 irrigation and settlement patterns are visible, although traces are rapidly disappearing due to expanding modern land use. Aim of this study is to unlock and integrate the rich information on landscape and archaeology, which only survives through the available historical imagery and some limited archaeological surveys. A GIS-based geomorphological mapping procedure was developed, using a variety of imagery, including historical aerial photographs, CORONA, Landsat and SPOT images. In addition, supported by the evidence from previous geological field surveys, archaeological elements were identified, mapped and included in a GIS database. The re...

Historical aerial photographs and digital photogrammetry for landslide assessment

Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Phil... more 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 landslide mechanisms requires extensive data records; a literature review identified quantitative data on surface movements as a key element for their analysis. It is generally acknowledged that, owing to the flexibility and high degree of automation of modern digital photogrammetric techniques, it is possible to derive detailed quantitative data from aerial photographs. In spite of the relative ease of such techniques, there is only scarce research available on data quality that can be achieved using commonly available material, hence the motivation of this study. In two landslide case-studies (the Mam Tor and East Pentwyn landslides) the dif...

Remote sensing for the study of fluvial landscapes in Lower Khuzestan, SW Iran

Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. 2009. Remote sensing for the study of fluvial l... more

Studying the driving forces of landscape change in the surroundings of the Late Bronze Age harbor town Halla Sultan Tekke, Cyprus. In: Geophysical Research Abstracts, vol. 14, pp. EGU2012-9413, European Geosciences Union

A complex of salt lakes, fringing the Mediterranean Sea between Larnaca and Cape Kiti, marks the ... more 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 the LBA societal collapse in the Eastern Mediterranean: from the invasion by the 'sea people', climate change to an earthquake or even a tsunami catastrophe. Nearby the archaeological site, the salt lake is protected from the Mediterranean Sea by a Pleistocene sandstone barrier.A second middle to late Holocene ridge separates the salt lakes completely from the Mediterranean Sea. Three faults, trending nearly perpendicular to the present-day coastline, are identified near the salt lakes. Human-environmental interactions that may have led to the abandonment of the ancient city of Hala Sultan Tekke are investigated by studying the se...

Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran

Long-term interactions between man and the fluvial environment-case of the Diyala alluvial fan, Iraq

The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, T... more The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013. Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes.

A History of Aerial Photography and Archaeology: Mata Hari's Glass Eye and Other Stories. By M. Barber. English Heritage, Swindon, UK, 2011. ISBN 978 1 848020 36 8. 194 mm × 252 mm. 304 pages. Price £25·00 hardback

The Photogrammetric Record, 2013

Human impact on alluvial fan development: can human niche construction provide a conceptual framework for long-term landscape evolution?

by Jan Walstra and Vanessa Heyvaert

Use of digital photogrammetry for the study of unstable slopes in urban areas: Case study of the El Biar landslide, Algiers

Recent developments in remote sensing techniques provide powerful tools for geomorphological stud... more Recent developments in remote sensing techniques provide powerful tools for geomorphological studies. The geometric and kinematic characterization of landslides are key factors in understanding the mechanisms of movement. The purpose of this publication is to show the potential of digital photogrammetry in the spatiotemporal study of landslides in urban areas. The case study focuses on the landslide of El Biar in Algiers. Comparison of digital elevation models generated following an established methodology shows the morphological evolution of the site. Orthophotos are used to measure surface displacements. The analysis of horizontal displacements between 1995 and 2007 shows that the landslide of El Biar can be divided into two zones: a peripheral zone moving at an average speed of about 5 cm per year and a central zone moving at an average speed of about 10 cm per year. Comparing the results with those obtained by traditional survey methods shows a remarkable consistency, thus validating the techniques used. This study demonstrates that digital photogrammetry, when combined with geological and geotechnical data, can improve the characterization and understanding of landslides mechanisms, and thus help defining mitigation solutions.

Geoarchaeological Research in Lower Khuzestan: State of The Art

The role of human interference on the channel shifting of the Karkheh River in the Lower Khuzestan plain (Mesopotamia, SW Iran

Quaternary International, 2012

This study is concerned with the Late Holocene floodplain history of the Karkheh River in Lower K... more 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 on the interpretation of Landsat and CORONA satellite imagery, (2) analyses of geological sequences, including the identification of sedimentary facies and radiocarbon dating of organic material, (3) an archaeological field survey of ancient settlements, and (4) consultation of historical documents, mainly Arabic texts from the 9th–14th century and European travel literature from the 16th-early 20th century. Three main channel belts of the Karkheh were identified (labelled Kh1, Kh2 and Kh3), corresponding to successive stages in the evolution of the floodplain. Two river shifts are documented in the datasets, both taking place within the last 2000 years. The first avulsion regards a shift from channel belt Kh1, once a tributary of the Karun, to the straight river bed of Kh2, taking place at least after 1240–1310 cal BP/710–640 AD. The second avulsion, from Kh2 to Kh3, is clearly documented in historical sources and happened in a single night event in the year 1837/113 cal BP. Reactivation of the Kh2 river bed and its irrigation canals can be attributed to the recent construction of an artificial canal bypassing the second avulsion point. Both river shifts were strongly influenced by human interference, whereby an artificial irrigation canal took over the entire river flow from the main channel belt. Most likely, a combination of human-induced factors, such as weakening of the river levees, high sedimentation rates and disadvantageous channel gradients, led to a situation prone to avulsion.

Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran

Geodinamica Acta, 2010

This paper presents a multidisciplinary approach for studying the evolution of an alluvial fan sy... more 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 identified, successively deposited by the Jarrahi river in progressively downstream/westward direction. Judging from archaeological and historical evidence, the successive phases appear to coincide with a relocation of settlement and irrigation activities. The distributary system of the present-day fan developed over a period of less than four centuries. It is suggested that management of levee breaks by man played a key role in such rapid fan development and in maintaining extremely low gradients. Judging from the extensive patterns of ancient irrigation canals, human activity also played an important role in the formation of the earlier fans.

Mapping Late Holocene Landscape Evolution and Human Impact – A Case Study from Lower Khuzestan (SW Iran

Recent advances in the fields of remote sensing and GIS provide the techniques to establish a fir... more Recent advances in the fields of remote sensing and GIS provide the techniques to establish a firm geomorphological framework to the historical and archaeological studies in the Mesopotamian region. This study presents a practical approach for the mapping of the semi-arid, alluvial landscapes of Lower Khuzestan. As elsewhere in Mesopotamia, the landscapes here are strongly affected by anthropogenic processes, most evidently expressed by widespread irrigation patterns. The image interpretation key and map legend are therefore designed explicitly to reflect these typical alluvial and human-induced landforms. The working procedure is based on easily accessible and inexpensive source material, notably Landsat and CORONA imagery, SRTM elevation data and readily available topographical maps, and was successfully applied in a case study on the evolution of the Jarrahi River. The resulting map, together with information from other disciplines, provided insights into the complex landscape evolution of the study area and a useful base for further research.

Reconstructing landscape evolution in the Lower Khuzestan plain (SW Iran): integrating imagery, historical and sedimentary archives

Landscapes Through The Lens: Aerial Photographs and Historic Environment, 2010

or from our website www.oxbowbooks.com Front cover: Étang de Montady, Languedoc-Roussillon in sou... more or from our website www.oxbowbooks.com Front cover: Étang de Montady, Languedoc-Roussillon in southern France. A remarkable pattern of fi eld boundaries created in the 13th century on a reclaimed lake photographed on 6 August 1944. Drains converge on the circle which lies at the centre of the former lake, with water then transported out of the shallow basin through a tunnel 1.3km long under the Hill of Malpas. TARA_MAPRW_106G_1960_4175, © Crown Copyright, RCAHMS Back cover: Erbil, the capital of Iraqi Kurdistan, is a claimant to the title of oldest continuously inhabited settlement in the world. The modern city is still dominated by the ancient tell, recorded here on 22 October 1948 when still a relatively small town. RAF_13A/131_3144,

Historical aerial photographs for landslide assessment: two case histories

Quarterly Journal of Engineering Geology and Hydrogeology, 2007

This paper demonstrates the value of historical aerial photographs for assessing long-term landsl... more This paper demonstrates the value of historical aerial photographs for assessing long-term landslide evolution. The study focused on two case histories, the Mam Tor and East Pentwyn landslides. In both case histories we explored the variety of data that could be derived relatively easily using an ordinary PC desktop, commercially available software and commonly available photographic material. The techniques to unlock qualitative and quantitative data captured in the photographic archive were based on the principles of aerial photo-interpretation and photogrammetry. The products created comprised geomorphological maps, automatically derived digital elevation models (DEMs), displacement vectors and animations. The measured horizontal displacements of the Mam Tor landslide ranged from 0.09 to 0.74 m a−1 between 1953 and 1999, which was verified by independent survey data. Moreover, the observed displacement patterns were consistent with photo-interpreted geomorphological information. The photogrammetric measurements from the East Pentwyn landslide (horizontal displacements up to 6 m a−1 between 1971 and 1973) also showed a striking resemblance to independent data. In both case histories, the vertical accuracy was insufficient for detecting significant elevation changes. Nevertheless, DEMs proved to be a powerful tool for visualization. Overall, the results in this study validated the techniques used and strongly encourage the use of historical photographic material in landslide studies.

Evaluation of the controls affecting the quality of spatial data derived from historical aerial photographs

Earth Surface Processes and Landforms, 2011

This paper is concerned with the fundamental controls affecting the quality of data derived from ... more 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 opportunity to evaluate the influence of the quality of archival material on the accuracy of coordinated points. Based on the statistical weights assigned to the measurements, precision of the data was estimated a priori, while residuals of independent checkpoints provided an a posteriori measure of data accuracy. Systematic discrepancies between the two values indicated that the routinely used stochastic model was incorrect and overoptimistic. Optimized weighting factors appeared significantly larger than previously used (and accepted) values. A test of repeat measurements explained the large uncertainties associated with the use of natural objects for ground control. This showed that the random errors not only appeared to be much larger than values accepted for appropriately controlled and targeted photogrammetric networks, but also small undetected gross errors were induced through the ‘misidentification’ of points. It is suggested that the effects of such ‘misidentifications’ should be reflected in the stochastic model through selection of more realistic weighting factors of both image and ground measurements. Using the optimized weighting factors, the accuracy of derived data can now be more truly estimated, allowing the suitability of the imagery to be judged before purchase and processing.

Aerial photography and digital photogrammetry for landslide monitoring

Geological Society, London, Special Publications, 2007

A review is given of the techniques that are available to extract relevant information from multi... more 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 inferring the mechanisms involved. Photogrammetrically derived products can be used to quantify these processes, providing distinctive advantages. Comparison of digital elevation models (DEMs) from different times provides detailed information on changes in surface topography, whereas orthophotos can be used to measure horizontal displacements. The various factors influencing the quality of the products are also identified. Examples from a case study on the Mam Tor landslide are used to illustrate the benefits of the different approaches.

Quantifying landform change

Applications of 3D Measurement from Images, 2007

Extracting landslide movements from historical aerial photographs

Landslides: Evaluation and Stabilization, 2004

Recent developments in digital photogrammetry allow high resolution quantitative data to be extra... more Recent developments in digital photogrammetry allow high resolution quantitative data to be extracted. This paper will present the digital techniques used to extract morphological change from a time series of historical aerial photographs. Initial results from a case-study at Mam Tor (Derbyshire, UK) show the potential of the methods to quantify past landslide movements. Photographs from 1958 and 1971 were used to create digital elevation models and orthophotographs and used for the analysis. Due to the poor geometry of one set of images the vertical accuracy was rather low. But, in spite of the low resolution, significant horizontal movements could be detected and these were consistent with observations from other researchers. Incorporation of additional epochs will extend the series and improve accuracies. This research is part of an ongoing project to model the response of landslides to future climate change.