scholarly journals Large-scale, Multi-temporal Remote Sensing of Palaeo-river Networks: A Case Study from Northwest India and its Implications for the Indus Civilisation

Author(s):  
Hector A. Orengo ◽  
Cameron A. Petrie

Remote sensing has considerable potential to contribute to the identification and reconstruction of lost hydrological systems and networks. Remote sensing-based reconstructions of palaeo-river networks have commonly employed single or limited time-span imagery, which limits their capacity to identify features in complex and varied landscape contexts. This paper presents a seasonal multi-temporal approach to the detection of palaeo-rivers over large areas based on long-term vegetation dynamics and spectral decomposition techniques. The use of multi-temporal data has allowed the overcoming of seasonal cultivation patterns and long-term visibility issues related to crop selection, large-scale irrigation and land use patterns. The application of this approach on the Sutlej-Yamuna interfluve (northwest India), a core area for the Bronze Age Indus Civilisation, has enabled the reconstruction of an unsuspectedly complex palaeo-river network comprising more than 8000 kms of palaeo-channels. It has also enabled the definition of the morphology of these relict courses, which provides insights into the environmental conditions in which they operated. These new data will contribute to a better understanding of the settlement distribution and environmental settings in which this, often considered riverine, civilisation operated.

2020 ◽  
Author(s):  
Sigrid Roessner ◽  
Robert Behling ◽  
Mahdi Motagh ◽  
Hans Ulrich-wetzel

<p>Landslides represent a worldwide natural hazard and often occur as cascading effects related to triggering events, such as earthquakes and hydrometeorological extremes. Recent examples are the Kaikoura earthquake in New Zealand (November 2016), the Gorkha earthquake in Nepal (April/May 2015), and the Typhoon Morakot in Taiwan (August 2009) as well as less intense rainfall events persisting over unusually long periods of time as observed for Central Asia (spring 2017) and Iran (spring 2019). Each of these events has caused thousands of landslides that account substantially to the primary disaster’s impact. Moreover, their initial failure usually represents the onset of long-term progressing slope destabilization leading to multiple reactivations and thus to long-term increased hazard and risk. Therefore, regular systematic high-resolution monitoring of landslide prone regions is of key importance for characterization, understanding and modelling of spatiotemporal landslide evolution in the context of different triggering and predisposing settings. Because of the large extent of the affected areas of up to several ten thousands km<sup>2</sup>, the use of multi-temporal and multi-scale remote sensing methods is of key importance for large area process analysis. In this context, new opportunities have opened up with the increasing availability of satellite remote sensing data of suitable spatial and temporal resolution (Sentinels, Planet) as well as the advances in UAV based very high resolution monitoring and mapping.</p><p>During the last decade, we have been pursuing extensive methodological developments in remote sensing based time series analysis including optical and radar observations with the goal of performing large area and at the same time detailed spatiotemporal analysis of landslide prone regions. These developments include automated post-failure landslide detection and mapping as well as assessment of the kinematics of pre- and post-failure slope evolution.  Our combined optical and radar remote sensing approaches aim at an improved understanding of spatiotemporal dynamics and complexities related to evolution of landslide prone slopes at different spatial and temporal scales.  In this context, we additionally integrate UAV-based observation for deriving volumetric changes also related to globally available DEM products, such as SRTM and ALOS.  </p><p>We present results for selected settings comprising large area co-seismic landslide occurrence related to the Kaikoura 2016 and the Nepal 2015 earthquakes. For the latter one we also analyzed annual pre- and post-seismic monsoon related landslide activity contributing to a better understanding of the interplay between these main triggering factors. Moreover, we report on ten years of large area systematic landslide monitoring in Southern Kyrgyzstan resulting in a multi-temporal regional landslide inventory of so far unprecedented spatiotemporal detail and completeness forming the basis for further analysis of the obtained landslide concentration patterns. We also present first results of our analysis of landslides triggered by intense rainfall and flood events in spring of 2019 in the North of Iran. We conclude that in all cases, the obtained results are crucial for improved landslide prediction and reduction of future landslide impact. Thus, our methodological developments represent an important contribution towards improved hazard and risk assessment as well as rapid mapping and early warning</p>


Author(s):  
Konstantine (Kiazo) Pitskhelauri ◽  
◽  
Mikheil Elashvili ◽  

Study of past changes in environment and, its effect on human society delivers key information to reconstruct the hystorical past but also to project future changes and their effects. Study focus on South-East Georgia, Caucasus region, which represents natural polygon of long term changes in the environment. Study area represents semi-arid Shiraqi plain in South-East Georgia (see the map below). It is characterized with annual precipitation <600mm and shows open dry steppic landscape today. However, recent data collected using remote sensing and archaeological studies, deliver evidences of early human inhabitation of this area, starting from the Paleolithic and forming a constant chain of active settlement through the time, until sudden abrupt at the end of the Bronze Age. Geomorphologically Shiraqi plane represents 800 sqr. km of almost flat area with average height of 600 m above Sea level, surrounded by chains of mountains creating a natural walls surrounding the plane. There are almost no settlements in the area, devoid of water resources today. Archaeo-Botanic and soil studies assume that the region was covered by forests, Hydro modelling shows possibility of existence of well developed water network with a shallow lake in the center of plane. Remote sensing data and resent archaeological excavations at Didnauri site provides clear evidences of early state formation, with favorable paleo-environmental conditions. The goal of current study is to shed light on historic changes in the environment of the region, its natural and anthropogenic factors and consequently response of human society on these changes.


2018 ◽  
Vol 43 (2) ◽  
pp. 193-214 ◽  
Author(s):  
Allan Derrien ◽  
Nicolas Villeneuve ◽  
Aline Peltier ◽  
Laurent Michon

Piton de la Fournaise is one of the world’s most active and visited volcanoes. Its summit crater (Cratère Dolomieu), the main tourist attraction, underwent a major caldera collapse in 2007 and its rim is not yet stabilized. In order to assess the caldera rim instability risk for visitors, we followed its structural evolution from 2007 to 2015. Using aerial photogrammetry campaigns, we mapped the unstable sites very precisely, carried out a quantitative analysis of the temporal evolution of these instabilities, and assessed the risks for visitors. Considering the 2008–2015 period, four sites close to the crater’s edge showed significant horizontal ground motion (0.5–2 m), fracture widening (average of 0.3–0.56 m) and large-scale mass wasting volumes (total of 1.8±0.1 × 106 m3). We infer two different processes at work: (1) to the west and north, toppling of the basalt units occurs after periods of fracture widening due to the combined effect of magmatic intrusions and long-term inflation/deflation cycles; (2) to the south and east, parts of the caldera rim slowly slide towards the caldera centre, with significant accelerations during periods of enhanced volcanic activity (in 2008–2010 and 2014–2015). The official observation platform is the most stable zone to overlook the Cratère Dolomieu. By contrast, the most frequently visited area of the rim (northwest) outside the official platform is also the most unstable.


Antiquity ◽  
2017 ◽  
Vol 91 (355) ◽  
pp. 254-256
Author(s):  
Antonio Blanco-González

In the Mediterranean region there are relatively few integrated, specialist research teams enga- ged in long-term and ongoing field- work. One of these rare and productive scientific collaborations is the ASOME (Arqueoecología Social Mediterránea, or Mediterranean Social Archaeoecology) group from the Autonomous University of Barcelona, Spain. The three volumes under review are authored by this team's lead researchers, and represent the first book-length publications from a long-term research project (2009–) on the Earlier Bronze Age El Argar culture (2200–1550 BC). They report the results of several excavations in the province of Murcia, Spain, supported by a combination of public and private funding. This ambitious initiative addresses ground-breaking research questions and offers solid and sustainable solutions for the conservation and preservation of these formerly neglected sites. Its aims, as summarised on the project's website, are: to create a systematic archive of information on the dispersed collections from earlier investigations; to undertake large-scale fieldwork on a series of key sites and to develop their public presentation; and to lay the foundations for an interdisciplinary research centre on prehistoric and Mediterranean archaeology (http://www.la-bastida.com).


2019 ◽  
Vol 12 (1) ◽  
pp. 55 ◽  
Author(s):  
Cong Ou ◽  
Jianyu Yang ◽  
Zhenrong Du ◽  
Yiming Liu ◽  
Quanlong Feng ◽  
...  

The greenhouse is the fastest growing food production approach and has become the symbol of protected agriculture with the development of agricultural modernization. Previous studies have verified the effectiveness of remote sensing techniques for mono-temporal greenhouse mapping. In practice, long-term monitoring of greenhouse from remote sensing data is vital for the sustainable management of protected agriculture and existing studies have been limited in understanding its spatiotemporal dynamics. This study aimed to generate multi-temporal greenhouse maps in a typical protected agricultural region (Shouguang region, north China) from 1990 to 2018 using Landsat imagery and the Google Earth Engine and quantify its spatiotemporal dynamics that occur as a consequence of the development of protected agriculture in the study area. The multi-temporal greenhouse maps were produced using random forest supervised classification at seven-time intervals, and the overall accuracy of the results greater than 90%. The total area of greenhouses in the study area expanded by 1061.94 km 2 from 1990 to 2018, with the largest growth occurring in 1995–2010. And a large number of increased greenhouses occurred in 10–35 km northwest and 0–5 km primary roads buffer zones. Differential change trajectories between the total area and number of patches of greenhouses were revealed using global change metrics. Results of five landscape metrics showed that various landscape patterns occurred in both spatial and temporal aspects. According to the value of landscape expansion index in each period, the growth mode of greenhouses was from outlying to edge-expansion and then gradually changed to infilling. Spatial heterogeneity, which measured by Shannon’s entropy, of the increased greenhouses was different between the global and local levels. These results demonstrated the advantage of utilizing Landsat imagery and Google Earth Engine for monitoring the development of greenhouses in a long-term period and provided a more intuitive perspective to understand the process of this special agricultural production approach than relevant social science studies.


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