Remotely sensed mid-channel bar dynamics in downstream of the Three Gorges Dam, China

The downstream reach of the Three Gorges Dam (TGD) along the Yangtze River (1560 km) hosts numerous mid-channel bars (MCBs). MCBs dynamics are crucial to the river’s hydrological processes and local ecological function. However, a systematic understanding of such dynamics and their linkage to TGD remains largely unknown. Using Landsat-image-extracted MCBs and several spatial-temporal analysis methods, this study presents a comprehensive understanding of MCB dynamics in terms of number, area, and shape, over downstream of TGD during the period 1985−2018. On average, a total of 140 MCBs were detected and grouped into four types representing small ( 2 km2), middle (2 km2 − 7 km2), large (7 km2 − 33 km2) and extra-large size (>33 km2) MCBs, respectively. MCBs number decreased after TGD closure but most of these happened in the lower reach. The area of total MCBs experienced an increasing trend (2.77 km2/yr, p-value 0.01) over the last three decades. The extra-large MCBs gained the largest area increasing rate than the other sizes of MCBs. Small MCBs tended to become relatively round, whereas the others became elongate in shape after TGD operation. Impacts of TGD operation generally diminished in the longitudinal direction from TGD to Hankou and from TGD to Jiujiang for shape and area dynamics, respectively. The quantified longitudinal and temporal dynamics of MCBs across the entire Yangtze River downstream of TGD provides a crucial monitoring basis for continuous investigation of the changing mechanisms affecting the morphology of the Yangtze River system

Spatial and Temporal Variability of Bank Erosion during the Period 1930-2016: Case StudyKolubara River Basin (Serbia)

The fluvial process is characterized by an intense meandering riverbed. The aim of this study was to perform a reconstruction of the lateral migration of a 15 km length of an active meandering river during the period 1930-2016. River morphological changes were analyzed and quantified from cadastral maps and aerial photographs as well as by geodetic survey and GIS. Hydrological characteristics and extreme hydrological events were evaluated in relation to bank erosion rate. The rate of bank erosion was markedly different from the long-term studied meanders, just like in the short-term period. During the 87 years of observation (from 1930 to 2016), the length of the Kolubara River was enlarged by 3.44 km. The average migration rate of the Kolubara River for monitored meanders in the period 1930-2010 was 1.9 myear(-1), while in the period 2010-2016, the average migration rate was 3.3 myear(-1). The rate of bank erosion was more intensive across the entire short-term period than during the longer period, and the maximum annual rate of bank erosion during the period 2010-2016 varied between 0.3 and 11.5 m. It is very likely that in the period from 2010, frequent discharge variations and rapid change of its extreme values caused more intensive bank erosion. These research results will be valuable for river channel management, engineering (soft and hard engineering), and planning purposes (predicting changes in river channel form) in the Kolubara River Basin

Remote sensing of geomorphodiversity linked to biodiversity — part III: traits, processes and remote sensing characteristics

Remote sensing (RS) enables a cost-effective, extensive, continuous and standardized monitoring of traits and trait variations of geomorphology and its processes, from the local to the continental scale. To implement and better understand RS techniques and the spectral indicators derived from them in the monitoring of geomorphology, this paper presents a new perspective for the definition and recording of five characteristics of geomorphodiversity with RS, namely: geomorphic genesis diversity, geomorphic trait diversity, geomorphic structural diversity, geomorphic taxonomic diversity, and geomorphic functional diversity. In this respect, geomorphic trait diversity is the cornerstone and is essential for recording the other four characteristics using RS technologies. All five characteristics are discussed in detail in this paper and reinforced with numerous examples from various RS technologies. Methods for classifying the five characteristics of geomorphodiversity using RS, as well as the constraints of monitoring the diversity of geomorphology using RS, are discussed. RS-aided techniques that can be used for monitoring geomorphodiversity in regimes with changing land-use intensity are presented. Further, new approaches of geomorphic traits that enable the monitoring of geomorphodiversity through the valorisation of RS data from multiple missions are discussed as well as the ecosystem integrity approach. Likewise, the approach of monitoring the five characteristics of geomorphodiversity recording with RS is discussed, as are existing approaches for recording spectral geomorhic traits/ trait variation approach and indicators, along with approaches for assessing geomorphodiversity. It is shown that there is no comparable approach with which to define and record the five characteristics of geomorphodiversity using only RS data in the literature. Finally, the importance of the digitization process and the use of data science for research in the field of geomorphology in the 21st century is elucidated and discussed

Análisis de detección de cambios en el espacio empleando interpretación de imágenes satelitales y estadística espacial

En esta tesis se implementan y evalúan dos metodologías para el análisis de detección de cambios (CD) en el espacio: 1) Análisis basado en objetos geográficos (GEOBIA). 2) Indicadores locales de asociación espacial (LISA) univariados y bivariados. Los resultados obtenidos con estas metodologías fueron verificados con datos tomados en campo. Las clases obtenidas usando GEOBIA tienen un 98% de exactitud y además esta técnica brinda interoperabilidad directa con los sistemas de información geográfica. Las clases obtenidas usando los índices univariados de Gettis y Ord y Moran, dan resultados del 92% y 67% de exactitud, respectivamente; ambos muestran limitaciones en la jerarquización de las clases. Sin embargo, el índice local de Moran bivariado presenta ventajas sobre los anteriores y da como resultado el 92% de exactitud, ya que se obtienen más niveles de clasificación de coberturas. Estas metodologías se aplicaron a un tramo del río Amazonas que hace parte del límite fronterizo entre Perú y Colombia para el período comprendido entre 1989 y 2015.Abstract: In this document two methodologies for the change detection (CD) analysis were assed and implemented. The first one is related to the geographic objects based on image analysis (GEOBIA), and the second one deals with univariate and bivariate local indicators of spatial association (LISA). The outcomes from these methodologies were verified with field data. Classes obtained through the GEOBIA methodology has a 98% accuracy, furthermore, this approach provides a direct interoperability with geographic information systems. Regarding LISA methodology, it was found that through the use of the Getis and Ord y Moran univariate indexes a 92% and 67% accuracy was achieved respectively. In this case both indexes show drawbacks in the class hierarchy. Nevertheless, it is worth to mention that the bivariate local Moran’s index has advantages over all the previous mentioned, given that more covering levels are obtained and a 92% accuracy in classes’ estimation. The methodologies were applied to an Amazon River segment, which is part of the boundary between Perú and Colombia for the time lapse between 1989 and 2015.Maestrí

Remotely Sensed Trajectory Analysis of Channel Migration in Lower Jingjiang Reach during the Period of 1983–2013

In China, the Lower Jingjiang Reach (LJR) of the Yangtze River could be one of the most complicated areas in terms of channel migration. The river had undergone many channel changes in the reach since the 18th century. Intensive human activities in recent decades, such as the construction of upstream dams and revetments, had directly affected the channel migration characteristics. The revetment would significantly diminish migration, whereas the reduced sediment caused by dams would increase bank erosion and bank failure risks. Satellite imageries of Landsat Multi Spectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) were employed to quantify the planform migration of the reach from 1983 to 2013 and to investigate the possible effect of human activities on the LJR channel evolution. Apart from the commonly used planform morphometric parameters, the migration direction was introduced to predict the future migration trends. Results showed that the LJR was gradually changing to a straighter channel, with sinuosity reducing from 2.09 to 1.9 and river length decreasing from 125.32 km to 113.31 km in the past 30 years. Planform morphometric parameters, such as migration rate of the channel centerline and erosion and deposition areas and rates, also decreased drastically in the past 30 years. The migration rate of the channel centerline decreased from 31.05 m·year−1 in 1983–1988 to 11.62 m·year−1 in 2009–2013. The lateral erosion and deposition areas decreased from 21.32 and 25.73 km2 in 1983–1988 to 4.83 and 5.83 km2 in 2009–2013. All of these findings indicate that the LJR tended to be in a steady state from 1983 to 2013 and was totally controlled by the bank revetments. However, the undercutting was strengthened because of the restrictive effect of revetments on lateral migration in the LJR. Moreover, the channel migrated to the left bank with a visible tendency as the total migration area to the left bank was approximately two times that of the right bank during the period. Consequently, the left bank of the LJR should be the focus of more attention in future migrations, and bank revetments of the left bank should be kept reinforced and adjusted with the change of water and sediment conditions

Remotely Sensed Trajectory Analysis of Channel Migration in Lower Jingjiang Reach during the Period of 1983–2013

In China, the Lower Jingjiang Reach (LJR) of the Yangtze River could be one of the most complicated areas in terms of channel migration. The river had undergone many channel changes in the reach since the 18th century. Intensive human activities in recent decades, such as the construction of upstream dams and revetments, had directly affected the channel migration characteristics. The revetment would significantly diminish migration, whereas the reduced sediment caused by dams would increase bank erosion and bank failure risks. Satellite imageries of Landsat Multi Spectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager (OLI) were employed to quantify the planform migration of the reach from 1983 to 2013 and to investigate the possible effect of human activities on the LJR channel evolution. Apart from the commonly used planform morphometric parameters, the migration direction was introduced to predict the future migration trends. Results showed that the LJR was gradually changing to a straighter channel, with sinuosity reducing from 2.09 to 1.9 and river length decreasing from 125.32 km to 113.31 km in the past 30 years. Planform morphometric parameters, such as migration rate of the channel centerline and erosion and deposition areas and rates, also decreased drastically in the past 30 years. The migration rate of the channel centerline decreased from 31.05 m·year−1 in 1983–1988 to 11.62 m·year−1 in 2009–2013. The lateral erosion and deposition areas decreased from 21.32 and 25.73 km2 in 1983–1988 to 4.83 and 5.83 km2 in 2009–2013. All of these findings indicate that the LJR tended to be in a steady state from 1983 to 2013 and was totally controlled by the bank revetments. However, the undercutting was strengthened because of the restrictive effect of revetments on lateral migration in the LJR. Moreover, the channel migrated to the left bank with a visible tendency as the total migration area to the left bank was approximately two times that of the right bank during the period. Consequently, the left bank of the LJR should be the focus of more attention in future migrations, and bank revetments of the left bank should be kept reinforced and adjusted with the change of water and sediment conditions

Religion and Folk Belief in Chinese Literature and Theatre

This edited volume offers a historical, textual and ethnoanthropological exploration of the meaning and value of religion and ritual and their form and function in relation to Chinese literature and theatre. The term ‘theatre’ is used here to refer broadly to various types of live performances—theatrical and non-theatrical; sacred and profane— presented in a religious setting, thus including ritual performance and oral performance. Likewise, literature in this volume broadly encompasses both written and oral literatures, including drama, poetry, hagiography, legend, mythology and prosimetric narrative or chantefable for telling and singing. The contributors to the issue draw on a wide range of materials from historical, philosophical and literary texts to field reports and archaeological finds to archived documents and local gazetteers to personal interviews and participant observations. While all the essays are collected under the theme of ‘Religion and Folk Belief in Chinese Literature and Theatre’, they differ from each other in subject matter, source material and research approach. Rich and varied as they are, these essays fall into two main categories, namely, a historical approach to religion and ritual recorded in (written and visual) texts and an integrated approach that combines historical inquiries into written and visual texts with ethnoanthropological fieldwork on religious rituals and associated performances