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Spatial variations of pressure patterns under the influence of large-scale atmospheric circulation create different conditions in terms of the intensity of synoptic systems affecting on extreme climatic phenomena. Regarding large-scale patterns, not only the changes of extreme events are considered, but also the changes and developments of synoptic systems on a regional scale are studied. Weather extremes have a great significance for society, as they pose a threat to human life and can result in enormous economic damage and disruption. The physical understanding and timely prediction of extreme weather events are of enormous importance to society regarding associated impacts. Extreme precipitation events (EPEs) is one of the most frequent natural hazards that affects the domain, eventually leading to floods. Synoptic systems in mid-latitudes such as blocking, ridge and troughs cause spatial changes in westerly waves. Spatial variations of atmospheric waves occur when, which normally move from west to east, change their main direction to the north or south. The occurrence of precipitation in the Middle East is related to the changes in waves and the position of the Mediterranean trough. Extreme precipitation events in the Middle East often result from tropicalextratropical interaction, whereby midlatitude forcing and poleward transport of tropical moisture are of central importance. The Mediterranean Sea region is considered to be one of the most important and major areas for circulation in the Northern Hemisphere, so that most of Iran's rain cyclones are formed over the Mediterranean Sea. In other words, Iran's rainfall in the cold period of the year is influenced by the Mediterranean circulation patterns. Evidence shows that the large-scale atmospheric circulation over the North Atlantic plays an important role in the Mediterranean circulation changes. We investigated the effect of mid-latitude atmospheric circulation changes on the position of the Mediterranean trough and the occurrence of super heavy precipitation in Iran. In this research, two category of upper atmosphere data were used. The first is daliy precipitation data for 350 stations that were made available by the Iranian Meteorological Organization (IRIMO). The second dataset is the geopotential height, relative vorticity, potential vorticity, U, Vcomponent of wind and Relative humidity, extracted from the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA5) reanalysis with grids at 0.25×0.25 resolution. In this regard, 150 extreme and widespread rains were identified, then using the sinuosity index, the changes of the most frequent contours (550, 565 and 575 decimeters) during the precipitations were identified over the North Atlantic and Mediterranean. The aim of this study was to find the relationship between the spatial variations of the upper level waves over the North Atlantic and the Mediterranean (-80° W to 70° E, 10° N to 60° N). According to sinuosity index, the minimum sinuosity value is about 1 indicating zonal flow. Any sinuosity value greater than 1 indicates an increase in atmospheric waves. The spatial changes of the Mediterranean trough are due to the meridian changes of currents over the North Atlantic, Europe. The blocking system over the Atlantic was responsible for both the amplification of the downstream trough, as well as the formation and expansion of the trough towards the Eastern Mediterranean. The results show that extremely heavy and widespread rains occur under the influence of the formation of the Mediterranean trough and the expansion of winds from the European side and the strengthening of the North Atlantic trough. The results showed that the position and changes of the Mediterranean trough are associated with the circulation pattern of the North Atlantic. Multiple Atlantic trough are associated with each case of Mediterranean trough downstream. The formation of the Atlantic trough causes an increase in the range of atmospheric waves and the formation of a ridge over Europe and the development of the Mediterranean trough. Under these conditions the Mediterranean Sea experiences 8 longitudinal and latitudinal changes compared to its average. Therefore, the spatial variations of the Mediterranean trough are due to the meridian changes of the European flows and the expansion of the high north side (tropical side) downstream of the western wind. Simultaneously with the formation of blocking over Europe in its eastern part, the dynamic ridge causes the transfer of cold winds over the Mediterranean, which strengthens and expands the Mediterranean trough to the east. These conditions, with the strengthening of the conditions of ascent and eastward movement of the Mediterranean trough, the Arabian Subtropical Anticyclone (ASA) also expands eastward. During the heavy rains of Iran, by strengthening the conditions of ascent and eastward expansion to the Mediterranean trough, the ASA also expands to the east. Therefore, with the location of the ASA over the northern Indian Ocean, the Arabian Sea, and the Oman Sea, more moisture is provided to the atmosphere, which is accompanied by the intensification of extremely intense and widespread precipitation. In general, the position of the Mediterranean trough during heavy rains is such that the western and southwestern regions of the country receive most of the precipitation. These conditions are more severe due to the orographic factor of ascent caused by the Zagros mountains in this region. [ABSTRACT FROM AUTHOR]

The climate, geomorphological changes, and hydrological elements that have occurred have all influenced future flood episodes by increasing the likelihood and intensity of extreme weather occurrences like extreme precipitation events. River bank erosion is a natural geomorphic process that occurs in all channels. As modifications of sizes and channel shapes are made to transport the discharge, sediment abounds from the stream catchment, and floods are triggered dramatically. The aim of this study is to analyze the flood-sensitive regions along the Pahang River Basin and determine how climate and river changes would have an impact on flooding based on hydrometeorological data and information on river characteristics. The study is divided into three stages, namely the upstream, middle stream, and downstream of the Pahang River. The main primary hydrometeorological data and river characteristics, such as Sinuosity Index, Dominant Slope Range and Entrenchment Ratio collected as important inputs in the statistical analysis process. The statistical analyses, namely HACA, PCA, and Linear Regression applied in river classification. The result showed that the middle stream and downstream areas demonstrated the worst flooding affected by anthropogenic and hydrological factors. Rainfall distribution is one of the factors that contributed to the flood disaster. There are strong correlations between the Sinuosity Index (SI) and water level, which indicates that changes occurred at both planform and stream classification. The best management practices towards sustainability are based on the application of the outcomes that have been obtained after the analysis of Pahang River planform changes, Pahang River geometry, and the local rainfall pattern in the Pahang River Basin.

The current study explores the planform morphological changes that have occurred in the upper segment of the Yamuna River by using Landsat images from 1979 to 2019. The river segment was divided into 18 sections at equal spacing, viz., S1 to S18, and the centerline and bank line shifting, channel width, alterations in meander geometry and braiding characteristics in terms of sinuosity index (SI) and braiding index (BI) were evaluated. The results indicate a maximum centerline shifting eastward at section S-5 and westward at S17 during 1999, with respect to the base year of 1979. The average eastward and westward centerline shifting remained insignificant. The average west bank shifting ranged from 0.407 km to 0.892 km east and 0.440 km to 0.418 km west, indicating relatively higher west bank shifting towards east. The average east bank shifting ranged from 0.335 km to 0.505 km east and 0.344 km to 0.896 km west, indicating a narrowing of the bank width throughout the segment length. During the assessment period, the river segment exhibited sinuous characteristics and non-braided behavior. The outcomes of this study could be useful in predicting future trends in river shifting and developing sustainable land use planning strategies along floodplains. [ABSTRACT FROM AUTHOR]

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Morphological studies are vital for water resources management, riverbank development, and flood mitigation. In this study, the sinuosity index and bank erosion were used to detect and quantify morphological changes using Landsat data (1990–2020) in the Barak river, India. The morphological changes were investigated in protected areas to analyze the effectiveness of existing protective structures on bank migration, which helps formulate better riverbank restoration plans. Using monthly discharge data from two stream gauge stations, the Seasonal Autoregressive Integrated Moving Average (SARIMA) models were developed. The extensive sediment transportation in the region necessitates studying both the river flow and morphological changes. The developed SARIMA model was used to predict river discharges up to 2025, being trained with data from 2006 to 2015. The validation of the model (2016–2018) shows that the mean absolute percentage error for discharge at two gauging stations is 29.78 and 23.52%, respectively. The analysis shows that the sinuosity index and bank erosion were inversely proportional. The SARIMA model showed that the future monthly discharge in the case study could be substantially higher than the observed series and affect river erosion simultaneously. This approach applies to many other meandering river management and identifies future morphological changes. HIGHLIGHTS Sinuosity index and riverbank erosion both are inversely proportional.; The efficiency of protection structures must be determined for alluvial river management. Inadequate protection structure planning might lead to downstream hazards.; The SARIMA model can accurately estimate future discharge by which segment-by-segment future morphological analyses are possible.;

The Madhumati River, located on the lower course of the Gorai River, experiences significant erosion and accretion, leading to annual changes in its morphological characteristics within the surrounding catchment area. Our study utilized Landsat satellite data and the ArcGIS platform to investigate the morpho-dynamic alterations and meander-bend formation mechanisms of the Madhumati River. Over a period of 43 years, from 1980 to 2023, we collected cloud-free images from Landsat 3, Landsat 5, Landsat 8, and Landsat 9 using the USGS Earth Explorer. River masks were then generated using the Water Ratio Index (WRI) and Sinuosity Index (SI) methods. In addition, each bend of the river was individually digitized to understand the bend development process, rate of movement, erosion and accretion, changes in river width, and sinuosity. Our findings reveal a gradual increase in river migration over the study period, attributed to significant erosion and accretion occurring at each bend. This research indicates a greater amount of erosion and accretion in river bends, with total sediment deposition exceeding net erosion throughout the study period. Most meandering bends have experienced considerable narrowing, indicating progressive river constriction over time. The construction of the Farakka Barrage contributed to higher sediment deposition from 1980 to 1990, whereas the Kamarkhali Bridge construction provoked an increasing amount of erosion from 1990 to 2010. Sediment deposition increased between 2010 and 2020. The erosion around the downstream bends grew once again when the investigation was carried up until 2023, proving beyond a doubt that the Kalna Bridge construction had an effect on this erosion rise. The increased sinuosity index of bends suggests heightened meandering. These findings have significant implications for engineering and geological practices, including infrastructure maintenance, expansion planning, riverbank protection measures, and agricultural and land management strategies concerning the Madhumati River. [Display omitted] • The Madhumati River experiences significant morphological changes annually, primarily driven by dynamic erosion and accretion processes. • Leveraging 43 years of Landsat data combined with ArcGIS analysis, we examined the evolution of meander bend formation. • Our analysis indicates substantial river migration, with notable increases in both erosion and accretion at multiple bends. • Infrastructure developments, including bridge construction, have directly influenced sediment deposition patterns and accelerated erosion between 1980 and 2023. • The findings provide critical insights for riverbank protection strategies, infrastructure planning, and sustainable land management practices. [ABSTRACT FROM AUTHOR]

Shifting of a river channel occurs continuously in the deltas and is a major predicament as it influences the land use and land cover of a region. Hence it is significant to understand the river course variation pattern for management plans as well as to carry out mitigation measures in the region. The current study attempts to understand the river shifting pattern dynamics in the Brahmaputra River with the help of satellite images and geospatial processing. The study has been carried out for three decades using satellite images from 1990 to 2021. To measure the meandering of river, sinuosity has been determined. Erosion and deposition were quantified using ArcGIS. The study interprets the influence of continuous erosion and deposition activities with that of the bank-line migration in the Brahmaputra River for three decades. The river shifted towards the south from 1990 to 2021 with an average sinuosity index of 4.43. Erosion is highest in 2011 along with the lowest deposition, around two times lower than in 2000 and 2021. The study suggests a dynamic change of course for the Brahmaputra river, impacting the land cover and vegetation with a potentiality of natural disasters.

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study focuses on finding the causes for the collapse of Sun temple, Konark, Odisha, India and the disappearance of the ancient Chandrabhaga river using satellite imagery and geophysical data. Gravity and magnetic anomalies near the Sun temple reveal the presence of two sets of faults trending NW–SE and NE–SW. The 3D gravity inversion depth model reveals an uplift-depression structure associated with these faults, which are steeply dipping in the proximity of the Sun temple. Reactivation of these faults is supported by evidences such as shifting of river channels, asymmetric arrangement of ox-bow lakes and combing features along the river bank, changes in the sinuosity index (SI) of the Kushabhadra, Kadua and Patharbuha rivers, all distributaries of the Mahanadi, against these faults. The most notable feature is the truncation of older channels by the present Patharbuha river, which instead of flowing towards the sea, meets the Kadua river to the east; this is interpreted to be linked to the reactivation of the NW–SE fault which results in the extinction of River Chandrabhaga. Remnants of River Chandrabhaga are present near the Sun temple. The timing of sediment deposition due to channel shifting, as well as fluvial morphological changes along the coast are found to be contemporaneous with the building and collapse of the Konark temple. [ABSTRACT FROM AUTHOR]

The anthropogenic activities affect the river channel as well as the whole system in different magnitudes and dimensions. Barakar River, the main tributary to the Damodar River in eastern India, is modified by several engineering structures. Hydrological parameters, such as monthly discharge, peak flow discharge and geomorphological factors, such as gradient, width–depth ratio, grain size, braid–channel ratio, sinuosity ratio, riffle-pool sequence, and stream power are taken into consideration to highlight the significant alterations of the river due to dam and bridge construction. The alterations are assessed with the help of hydrological data, satellite images, and digital elevation data along with field survey. The downstream section of the dams, the river is characterised by high braiding, sinuous, total and unit stream power along with the presence of a box-shaped bedrock channel, high gradient, bed coarsening and armouring due to the release of high-velocity sediment-free 'hungry water'. In the upstream reach, the grain size decreases towards the dam, and it increases suddenly with poor sorting at the immediate downstream regime of the dam. The effects of bridges on the Barakar river morphology include an increase of gradient, width and depth of the river channel at the downstream of the bridges. The construction of bridges influences riffle-pool sequences. Thereby, the pool depth spacing is greater than the riffle crest spacing. However, the integration of natural as well as human-induced factors can be the best approach to understand the anthropogenic alteration of the river. Moreover, construction of some check dams at the upper section of the tributaries of the Barakar River can be very effective for morphological stability. [ABSTRACT FROM AUTHOR]

The streams of rivers are extremely complex in nature. Rivers are beneficial for natural vegetation, animals, living organisms and human communities. The river provides the possibility of drinking water and irrigation of agricultural fields. Rivers are considered as active land cultivators with erosion and sedimentation. Some of the negative effects of rivers such as floods are considered as a natural disaster. Such natural disasters have been shown when the river by anthropogenic activities by changing the shape of the river and arched their plans change. Meandering parts of the rivers are vulnerable to floods. Therefore, river studies are very important in terms of hydraulic characteristics, sediment, width to depth ratio, morphology and arched plan. Kaleibar Chai basin has located on the North West of the country. This research pays attention to the arcuate plan of Kaleibar River from the city of Kaleibar to Jananloo village (one of the branches of Aras River). The study region is part of Kaleibar Chai River with 72 km of length. The channel consists of right, waving, meandering, and braided patterns. The study of horizontal plan of the river in relation to different active processes shows the mutual relationship between hydrological parameters and the materials in the river. The continual changes in sinuosity index in the channel are indicators of variations in the river behavior. For doing this research we used Google Earth and DEM 10m images. The river was divided into 4 openings in which topographic conditions were considered. The river sinuosity index was calculated for all 4 openings in GIS software under the formula: TSI= . In this equation TCI is topographic sinuosity index, CL is the length of the river channel, Al is the aerial length of the beginning and ending part of the channel. The maximum sinuosity index for different lengths of the Kaleibar Chai River was estimated at 1.05 to 1.83. The heterogeneity of bed materials causes erosion and deposition on the river bed of Kaleibar Chai. Erosion and depositional processes occur in the area during the spring and fall floods. The variety of materials and their sizes cause erosion and the collapse of the brinks and the loop in sinuosity index, which finally lead to channel changes. The study of sinuosity index and the identification of rivers patterns help ease the planning procedure

Ramganga River is characterized by frequent planform changes in its lower reaches. The plain topography and frequent floods occurrence are powerful agents to change the river morphology. This paper presents a detailed account of channel planform dynamics of River from 1780 to 2017. Spatial data were analyzed in GIS to determine changes in sinuosity, centerline migration rates and large-scale dynamics of the River. The results revealed its overall shifting towards south-west direction. In upstream, planform repeatedly oscillated in its floodplain. In the downstream, a highly stable reach is found which does not show any significant shifting character in last 50 years, but a major avulsion of 11 km is found in its confluence with the Ganges. The study provides recent and reliable information on the channel planform dynamics and will help as a decision support tool for designing and implementation of drainage development works. [ABSTRACT FROM AUTHOR]

Ongoing demands for irrigation, drinking water supplies and hydropower generation encourage human beings to construct dams and reservoirs on rivers. Such engineering structures together with embankments may protect downstream areas from flooding, can give short-term benefits but may degrade the natural or pristine condition of a river by altering the longitudinal and lateral connectivity of water and sediments. This study analyses the human-induced changes in the channel belt and floodplain morphology of the Yamuna River between Wazirabad and new Okhla barrages using topographic maps and satellite image. In the pre-dam condition (1867–1868), the Yamuna River had a highly braided channel pattern compared to the post-dam situation. After construction of the Tajewala, Hathnikund and Wazirabad barrages, the longitudinal connectivity of sediments and discharge were disturbed so that bar areas were reduced and values of the braided index declined. Dam-induced moderation of peak discharges, rapidly growing population, increasing length of embankments and roads in the floodplain are the major reasons behind the urbanization of Yamuna floodplain in Delhi. This study also shows that the increasing length of engineering structure caused a reduction in channel belt area and its width. Results of the present study are useful for the environmentalists, policy makers and earth scientists working on the restoration and management of floodplain between Wazirabad and new Okhla barrage. [ABSTRACT FROM AUTHOR]

Lateral migration of the Bhagirathi River temporally creates unavoidable geomorphic hazards in West Bengal, India. The Bhagirathi River flows SW for ~67.30 km between the confluence point of Ajay and Jalangi rivers in East Burdwan and Nadia districts of West Bengal. The course of Bhagirathi is notably migration prone and cultivates problematic changes along its course over time. In the study, we have looked into its migration tendency and unpredictability for past 238 years and then predicted the lateral shifting of river centerline using temporal satellite imageries — Landsat-5 (TM) of 1987 (8, December), 1995 (28, January), 2005 (7, January) and LISS-IV satellite imagery (2017, 5 January);SOI Toposheet — 1968-1969 (79A/2, 79A/3, 79A/6 and 79A/7) and Rennell's map of 1779. Other highlights are the quest of fluvial features, oxbow lakes, mid-channel bars, channel migration rate, meander geometry, channel sinuosity in different parts of river course and the parts that experience intensive bank erosion. The entire river course has been subdivided into three segments; viz. reaches A, B and C. Investigation displays that degree of sinuosity decreases from its anterior course (1968) to the existing course (2017). Reach-specific outputs display that reach B is highly sinuous (SI value 1.94 in 2017) and SI increases temporarily, whereas for reaches A and C it decreases with time. The rate of migration is higher in reach B than that in reaches C and A. The study displays a notably decreasing trend of migration in comparison with its previous lateral migration and shows that the migration nature over time is intensively inconsistent and unpredictable except very few portions of the river course. The nature of deposition within the river channel shows an unstable behavior during the entire period of the study. Meander geometry depicts a rapid change of river course innate to meander bends and shows a higher rate of migration by meander loop cut-off rather than lateral migration that reflects the inconsistency, erosion vulnerability and unpredictable nature of migration. The present work offers a valuable source to comprehend channel changes in Bhagirathi River and serve as an efficacious base for river-bank migration and erosion hazard planning and management. [ABSTRACT FROM AUTHOR]

The urban expansion of any settlement implies changing natural environment and gradually transforming it into an anthropogenic one to assure the needs of the community. A first step in urban planning is to identify the changes that have been made, and this study reconstructs the anthropogenic changes induced to the Jiu floodplain in the last 150 years, through multi-temporal spatial comparisons, geomorphological characteristics and anthropological and environmental transformation indicators. The processing of historical cartographic materials and current satellite imagery highlights the dynamics of the wetlands and the built-up area in the Jiu floodplain between 1864 and 2017. The urban expansion required flood protection works that were carried out along the canals and lakes resulting from the drainage of the ponds and marshlands. On the course of the Jiu hydro-technical works of straightening, embankment and regularization were achieved, which led to the transformation of the course from a highly meandered one as it was in the second half of the 19th century into a sinuous one in 2017. The study is a useful tool in urban planning, by centralizing the changes in the floodplain, the anthropogenic works carried out and the changes of the Jiu course within the analyzed sector. [ABSTRACT FROM AUTHOR]

Despite a long research history, little is known about the Roman road network in the northern part of the Civitas Menapiorum. In late nineteenth- and early twentieth-century publications researchers established the idea that Roman roads ended at the transition between the loamy and sandy areas. Others indicated that such roads were not yet located. During the last twenty years researchers have presumed the existence of five supralocal Roman roads in Sandy Flanders. However, their exact routes remained unclear. In this study a landscape archaeological approach is applied to study these roads and to suggest a series of possible routes. Based on recent LiDAR data and soil maps, least cost path analyses are performed in ArcGIS. Recent archaeological findings and double linear marks, visible on both oblique and vertical aerial photographs, are used to test the accuracy of the least cost paths. Finally, the names of present-day streets are used to clarify the continuity of Roman roads in the landscape. [ABSTRACT FROM AUTHOR]

In order to develop geomorphic criteria for distinguishing and locating abandoned channels and meandered belts, in this paper we examined geomorphologic characteristics from the Mun River, one of the main rivers in the Khorat Plateau, northeastern Thailand. Upstream of Mun River originated at southwestern rim of the Khorat Plateau where the river now cuts through sandstone basement. Meandering process shaped meander from upstream ending at low-lying plain about 30 km downstream from the Mun Bon Dam reservoir, and this process displays given values of geomorphic parameters including sinuosity index (SI), channel width (W) and radius of curvature (Rc). Sinuosity index was calculated to express the sinuosity of the channel. The relationship between W and Rc helps to predict channel stability and also comprehend the possibility of cutoff process. As a result, paleo- and recent flow directions of the Mun River are similar from southwest to northeast. Geomorphic parameters from eight river reaches have changed through time since 1974-2015. Two abandoned channel belts were identified, and they own an average channel width of 35 and 16 m, whereas the Mun River nowadays is of 12.7 m. SI values of two abandoned channel belts are categorized as meandering river system. Relationship between meander migration rate and bend curvature suggests that the Mun River possesses low erosion rate between 0.71 and 2.64 m/year since 1974 to the present. This rank of Rc/W ratio suggests stable state of river bank migration. Different migration indicates discontinuous meandering process from individual belt. Lateral migration rate was also decreased after Mun Bon Dam was constructed upstream. [ABSTRACT FROM AUTHOR]

This paper will consider the contribution that changes in road geometry and driver visual information make to the incidence and distribution of road casualties in different driving environments. This relationship will be explored specifically for the Kings Highway, a major arterial road connecting Queanbeyan with coastal southern New South Wales, Australia. It introduces and suggests a new empirical approach of plotting crashes with road segmentation, calculating sinuosity indices and grades as key features of road geometry, and critical visual points as a behavioural component of road curvature, within a GIS context. It is an approach that might be used when detailed road geometry data is not available. The visualisation and segmentation approach in this research might be used for summarising crash rates and road geometry factors, and for comparing day/night and eastbound/westbound driving conditions. The results suggest some early interpretations for detailed road safety studies that might be considered at local or national levels. The rate of crashes increases according to changes in road geometry factors during the day and for eastbound travel. This is not the case for night driving where the incidence of crashes is similar on both straight and curved roads segments due to the headlight effect and limited background visual field. Crash clusters at day-time may be due to the stronger effect of road geometry (e.g. combination of curvature and vertical grade) on driver behaviour travelling eastbound. The outcomes suggest that it might be essential to consider the effect of environmental factors in any road safety and crash analysis studies. [ABSTRACT FROM AUTHOR]

A bridge is a structure built to span physical obstacles such as a body of water, valley or road for the purpose of providing passage over the obstacle. Bridges over rivers cause an alteration of flow and modify the flow characteristics because of the flow obstruction. Remote sensing and GIS techniques have been used to study the alterations in river meandering characteristics. The objective of this study is to analyse the changes in river characteristics downstream of a bridge using satellite images for the lower Ganges River at two bridge sites in Bhagalpur and Munger in Bihar, India. ARC-GIS is used to calculate the normalised difference water index (NDWI), which has the capability to represent water bodies adequately from space. Based on NDWI maps, the river channel length and downvalley length were measured for different spatio-temporal conditions. The above parameters (channel length and downvalley length) were used to estimate the Sinuosity Index under 14 spatio-temporal situations. The Sinuosity Index (i.e. an indicator of local river fluvial characteristics) varies significantly because of the effect of bridges and their associated structures. There was an increase in the Sinuosity Index of 30 % magnitude in an 8-year time period (2006-2014) after the bridge construction phase at both locations. The pre-construction phase of the bridges indicates minor changes in the Sinuosity Index during the 9-year period from 1987 to 1996. The NDWI analysis also reveals that the river characteristics changed considerably in the pre- and post-bridge scenarios while the change was less significant for pre- and post-flood events (May 2014 to October 2014). [ABSTRACT FROM AUTHOR]

The study has taken the opportunity of Landsat (1990-2010) satellite images, SRTM digital elevation model data and water discharge data of one gauging station to understand the temporal dynamics of the Tista River in the last two decades. Along with the enormous impact of flash floods the construction of Gajoldoba Barrage has played the key to change the braided planform of the river. The river upstream of Gajoldoba Barrage is characterized by eastward shifting (upper portion), westward shifting (an immediate upper portion of the barrage), decreasing sinuosity, increasing braid-channel ratio, an increase in the number of sub-channels and a reduction in the size of channel bars etc. The river downstream of the barrage is characterized by westward migration, decreasing sinuosity, increasing braid-channel ratio, an increase in the number of subchannels, and a reduction in the size of channel bars etc. moreover, the study reflects a significant comparison of the morphological dynamics between the up and downstream of the river. [ABSTRACT FROM AUTHOR]

Hydrogeomorphologically, the study of river meandering provides information on the tendency of rivers to reach and form a state of equilibrium. The process of meander changes is important in order to identify the environment-related causes that occur naturally or vice versa. Sedimentation, erosion, flood, and water quality problems usually are being specifically studied, but in a broad view, changes in the platform of the river affect all the problems that occur. This article discusses the effects of the meanders evolution changes from land use and climate change in the upstream of Sungai Pahang in over 61 years from 1932 to 1993. Based on Geographical Information System (GIS), the topographic maps, scaled to 1:50,000 in geo-reference, were overlaid and digitalized. The main alignments of the upstream reach from those years were superimposed, and the changes were identified based on sinuosity index. In this task, the study areas were divided into two major plots for river plan classification. The results indicated that the average of alignment on the sinuosity index is 1.24 to 1.48 in plot A, while in plot B, the results are not stable. Based on historical results, a very significant change of meander was identified in the subplot Ua3 in plot A, where 21.2 % segments were recorded with high changes. This could be associated with significant exploration at hilly areas in the Cameron Highlands. Large-scale changes in land use pattern are coupled with global climate change where total rainfall recorded was at 2,760 mm in plot A on the year 1993. While for the plot B segment, the percentage of meander changes is 41.5 % versus plot A which is 86.7 %. This is due to the fact that plot B is the forest reserve and national park, areas with natural environment, possessing lithosols characteristic soils in the upper plot B area, and the trend of land use change (forested areas) is substantially lower than in plot A, with a 10 % difference. The aim of this study is to understand the impact of the land use changes due to climatic conditions on the meander evolution changes at the upstream reach of the Pahang River and suggest a number of solutions to mitigate or adaptation strategies to cope with those changes in the future. [ABSTRACT FROM AUTHOR]

Identification of fluvial landforms is of paramount importance in river planform change studies. Satellite remote sensing is a proven technology to identify fluvial landforms and map the associated changes over a period of time because of its synopticity and repetivity. Sindh River, which is the lifeline in central India, changes its course in the alluvial plain, mainly due to meander cutoffs. In this study, multi-temporal satellite data over a period of 23 years were used to find out the behaviour of a meander loop in parts of the Sindh River. It was found that the meander cut off in this loop is a typical neck cutoff unlike chute cutoff in general. The river shows a decreasing trend of sinuosity index during the observation period. [ABSTRACT FROM AUTHOR]

Abstract: The main idiosyncrasy of a typical karst system is the presence of a three-dimensional network of conduits behaving as drains in the system and being responsible of both the quick response of karst springs to rainfall events and the complex distribution of solutes in the system. A morphometric analysis of the three-dimensional geometry of conduits provides quantitative measures that can be used in a range of applications. These morphometric parameters can be used as descriptors of the underground geomorphology, they provide information on speleogenesis processes, they can be correlated with karst denudation ratios, they can be used to control the simulation of realistic stochastic karst networks of conduits, and they can be correlated with hydrogeologic behaviour of the karst system. The main purpose of this paper is to define, describe and illustrate a range of morphometric indexes and morphometric functions that can be calculated nowadays because the availability of three-dimensional topographies provided by speleological work and the availability of the computational and graphical power provided by modern computers. Some of the morphometric parameters describe the existence of preferential directions of karstification, others describe the kartification along the vertical and the possible presence of inception horizons. Other indexes describe the shape complexity of the karstic network, whilst other indexes describe spatial variability of the conduit geometry, and other parameters give account of the connectivity of the three-dimensional network. The morphometric analysis is illustrated with a three-dimensional karstic network in Southern France. [Copyright &y& Elsevier]

Quantitative analysis on the shape of 959 tropical storm (TS) tracks in the North West Pacific (NWP) basin was carried out over the period from 1977 to 2016 by using International Best Track Archive for Climate Stewardship (IBTrACS) provided by National Oceanic and Atmospheric Administration (NOAA) based on an established track sinuosity metric. Track sinuosity is a measure of deviation of a storm track from its straight–line path between the cyclogenesis and cyclolysis locations. More sinuosity in the storms' tracks makes it rather challenging for the atmospheric models to accurately assess the storms' respective locations on the map and potentially causes higher damages due to lack of precise information about their movement. Statistical analysis was carried out on spatial and temporal trends (monthly to decadal) of the TS track shape and the obtained results were mapped based on sinuosity categories within a GIS environment. The sinuosity distribution results are normalized using a cube–root transformation function to reduce skewness and obtain sinuosity index (SI). Distinct enhancement of TS sinuosity was noticed from the months July to October (JASO). It is also detected that early months of TS season like June–August have dominance of more predictable straighter storm tracks over sinuous kind of tracks, and vice-versa in the case of late months of season like September–October. It is also evident that there is a one- to three-year cyclic pattern of changing sinuosity over the NWP basin. The 1987–1996 decade had the maximum dominance of sinuous tracks in comparison to the other three decades. Significant longitudinal eastward shift (from 110°–140° E to 130°–160° E) in majority of cyclogenesis locations is observed as sinuosity in storm track increases from straight to sinuous patterns. Similar shift for latitudinal track was not found. Finally, we investigate the sinuosity based on the warm/cold phase of the ENSO. Warm phase of ENSO is found to be associated with a greater number of TS with higher SI values in the NWP basin. These TS during warm phase mostly originate in the eastern part of the basin where a vast open area of warm sea surface temperature encourages their formation and intensification. Lastly, the study found a moderate positive relationship between SI and TS' longevity and distance coverage, which are crucial information for disaster risk assessment, mitigation and preparedness. • From July to October the TS tracks gradually increase their sinuosity in the NWP. • Eastward shift in most of TS genesis positions is seen with increase in track sinuosity. • Warm phase of ENSO is associated with a greater number of TS with higher SI values. • Early cyclone season months dominance of sinuous TS tracks vice-versa in late months. [ABSTRACT FROM AUTHOR]

Assessment and monitoring of river morphology own an important role in river engineering; since, changes in river morphology including erosion and sedimentation affect river cross-sections and flow processes. An approach for River Morphodynamics Analysis based on Remote Sensing (RiMARS) was developed and tested on the case of Mollasadra dam construction on the Kor River, Iran. Landsat multispectral images obtained from the open USGS dataset are used to extract river morphology dynamics by the Modified Normalized Difference Water Index (MNDWI). RiMARS comes with a river extraction module which is independent of threshold segmentation methods to produce binary-level images. In addition, RiMARS is equipped with developed indices for assessing the morphological alterations. Five characteristics of river morphology (spatiotemporal Sinuosity Index (SI), Absolute Centerline Migration (ACM), Rate of Centerline Migration (RCM), River Linear Pattern (RLP), and Meander Migration Index (MMI)), are applied to quantify river morphology changes. The results indicated that the Kor River centerline underwent average annual migration of 40 cm to the southwest during 1993–2003 (pre-construction impact), 20 cm to the northeast during 2003–2011, and 40 cm to the south-west during 2011–2017 (post-construction impact). Spatially, as the Kor River runs towards the Doroudzan dam, changes in river morphology have increased from upstream to downstream; particularly evident where the river flows in a plain instead of the valley. Based on SI values, there was a 5% change in the straight sinuosity class in the pre-construction period, but an 18% decrease in the straight class during the post-construction period. Here we demonstrate the application of RiMARS in assessing the impact of dam construction on morphometric processes in Kor River, but it can be used to assess other riverine changes, including tracking the unauthorized water consumption using diverted canals. RiMARS can be applied on multispectral images. Unlabelled Image • River delineation process does not rely on threshold segmentation methods. • Gap-filling module iterates the point regeneration process to create the river path. • RiMARS can detect the meanders of the river. • RiMARS employed five developed indices to assess the morphological alterations. • Major Meander Index is used as a complementary alternative for Sinuosity Index. [ABSTRACT FROM AUTHOR]