An Analysis of the Morphological Changes of Surma River in Sylhet District Using Multitemporal Remote Sensing Images

The Surma River is one of the most important rivers in the northeastern part of Bangladesh, which has changed significantly throughout history. Very few studies have taken place to understand this river's complex behavior, which characterizes its morphology. The core objective of this research is to analyze the river dynamics to understand the morphological changes of the river from 1978 to 2021. Remotely sensed satellite images of 1978, 1989, 1999, 2011, and 2021 were secondary data. The whole working procedure is the correction of satellite images, application of normalized difference water index (NDWI), demarcation of the river bank line using bank line methods, quantification of the erosion-deposition using an overlapping method, demarcation of central line shifting, measurement of the river width and finally the sinuosity index metering for 43 years. The river has changed significantly in several locations within the period in Sylhet District. Ten bends, three segments, and 200 points were taken to quantify the change dynamics. The overall analysis found that the left bank shifted more than the right bank. According to the findings, the deposition rate (80.98m/year) of river Surma is almost double the erosion rate (42.11m/year), which causes a significant decline in river width from 163m in 1978 to 123m in 2011. After counting 200 sample points, the result concluded that the average central line shifted more than average (79.50m) at 38 points indicates three major locations- Kanaighat, Dakshin Banigram, and Lalargaon. Finally, the sinuosity index found that the river became more meander following its shifting movement except the ninth bend near Kandigaon. The riverine people indicated several anthropogenic factors, e.g., encroachment, illegal construction, pollution, illegal sand extraction, as the key issues which should be intervened and take necessary action.

Channel Migration of the Meandering River Fan: A Case Study of the Okavango Delta

Okavango delta is a typical distributive fluvial system, which is composed of a series of sand island-river-swamp networks. River migration in the Okavango delta is analyzed by using satellite images from Google Earth and Alaska Satellite Facility (ASF). Four configuration characterization parameters are selected to depict and measure the meandering river. These four parameters are sinuosity index (S), curvature (C), the difference of along-current deflection angle (Δθ) and expansion coefficient (Km). In the fan, the channel migration is mainly asymmetric. According to geomorphic elements and associated features, Okavango Delta can be subdivided into three zones: axial zone, median zone and distal zone. Under the influence of slope, climate and vegetation, different migration modes are developed in different zones. As the river moves downstream, the sinuosity index of the river on the Okavango Delta decreases downstream. Based on the characteristics of different zones, the sedimentary facies model of a single source distributive fluvial system of a meandering river is proposed. The models of channel migration and sedimentary facies have wide application. This research will not only provide a basis for the prediction of future river channels but will also provide important theoretical guidance for the study of the sedimentary morphology of underground reservoirs.

Linkages Between Sinuosity Index and Flood Sustainability: A Study of Morna River (Maharashtra), India

The morphological changes in the river channel over periods that occur due to the flood events, affected the sinuosity index of the river channel. The river characteristic like sinuosity also determines the intensity of flood in a channel. Recent flood losses have increased as a result of variability in rainfall; simultaneously such problems are coming up with sustainable development. The attempted research study has been carried out to evaluate and understand the river channel changes and bank stability of the Morna river in Maharashtra. The research work also identified the pattern/planform of the river. Morna river meets Warna river near the Mangle village. Most of the streams in the upper basin area are non-perennial. The occurrence of floods takes place due to seasonal rainfall. An index of Sinuosity was used to analyze variation in river courses, as well as identify stability and instability. Therefore, this may facilitate predicting probable riverbank erosion sites and also support sustainable flood management planning for these sites during forthcoming flood events. The sinuosity index of the Morna river ranges from 1.09 to 1.44. The sinuosity indexes for the Morna river and tributaries of its sub-basins/watersheds have been calculated using geospatial techniques. The disparities in sinuosity indexes of the Morna basin and sub-watersheds having a good correlation with slope of the river , fluvial processes, water discharge and hydraulic aspects of the river channel. Seasonal potential flood risk for the agricultural land may be found at the confluence of the Warna river and its tributary Morna river when it receives heavy rainfall in upstream.

MORPHOGRAPHIC STUDY OF BOIULUI VALLEY HYDROGRAPHIC BASIN

The aim of the present paper is to determine the morphometric parameters and features of Boiului Valley hydrographic basin. The basin is located in a karst area, in Pădurea Craiului Mountains, Romania, which makes it special, as the rivers flow through soluble rocks. We selected a small basin in order to analyse its morphometric elements and check if the morphometric laws of hydrographic basins are respected in the same way by the rivers flowing in karst areas. We applied the classical working method, that is processing the information from the topographic maps and with the help of the ArcGis soft we managed to measure the major morphometric indicators: the surface of the basin, the area, the shape factor, the length and width of the basin, drainage basin asymmetry factor and sinuosity index.

Morphometric and Sinuosity Analysis of Tlawng River Basin: A Geographic Information System Approach

Channel plan-form patterns of river Tlawng has been studied which shows that there is variation in the sinuosity index. This variation is a sign of changing characteristics and behavior of the river. The average sinuosity of the river is 1.41. The sinuosity index is higher in the lower course of the river as it flows through alluvial plain. GIS techniques have been used for studying morphometric parameters. There are 6736 streams in the Tlawng river basin which shows that the topography is still undergoing erosion as the number of stream is high (Zaidi, 2011). The river has low bifurcation ratio which indicates less possibilities of flooding. The drainage density indicates the higher permeable subsoil and moderate to thick vegetative cover. The stream frequency value of the Tlawng river basin is 1.30 streams / km2 which shows a positive relation with drainage density.

Uso do LiDAR para avaliar os padrões hídricos de bacias em áreas urbanas: Caracterização fisiográfica da bacia do Rio Beberibe, PE

A caracterização fisiográfica, consiste no levantamento dos principais parâmetros fisiográficos de uma bacia, que podem ser extraídos de mapas, fotografias aéreas e imagens de satélite, e se apresenta como uma ferramenta útil ao planejamento e gestão dos recursos hídricos, por existir uma forte correspondência entre as características físicas de uma bacia hidrográfica e seu regime hidrológico. O presente estudo se propõe a caracterizar fisiograficamente a bacia hidrográfica do Rio Beberibe utilizando os dados do sensor LiDAR com resolução espacial de 5 m em uma escala de 1:5000, provenientes do programa PE3D (Pernambuco Tridimensional). Os resultados obtidos sobre os parâmetros geométricos, levaram à conclusão de que a bacia hidrográfica do Rio Beberibe não é naturalmente propensa à ocorrência de enchentes, por possuir uma forma alongada. Sobre os padrões de drenagem, foi possível concluir que a bacia possui uma drenagem rica e escoamento superficial fluido e ágil, que seus canais possuem perfis retilíneos, e que se trata de uma bacia de 6ª ordem. Acerca das características do relevo, foi constatado que a bacia não possui picos de altitudes elevados, porém uma considerável amplitude altimétrica, além de que na declividade da bacia não estão apresentadas inclinações bruscas. Using LiDAR to evaluate water patterns in urban areas basin: Physiographic characterization of the Rio Beberibe basin, PE A B S T R A C TThe physiographic characterization consists in the survey of the main physiographic parameters of a basin, which can be extracted from maps, aerial photographs and satellite images, and presents itself as a useful tool for planning and management of water resources, as a consequence of the influence between the physical characteristics of a river basin and its hydrological behaviour. The selection of the Beberibe river basin for the development of this research was made due to their importance for the macrodrainage of the state of Pernambuco, and because they are located in an area of strong urban activity. Thus, these areas present strong socioeconomic activity, which configures them as spaces where water planning is crucial for the conscious use of their resources. Faced with this scenario, the present study proposes to physiographically characterize the Beberibe river basin using LiDAR sensor data with a spatial resolution of 5 m on a scale of 1:5000, from the PE3D program (Three-Dimensional Pernambuco). The main morphometric parameters obtained for the Beberibe River basin were grouped into three groups of characteristics. The geometric characteristics, which consist of the following parameters: drainage area (A), basin perimeter (P), axial length (L), compacity coefficient (Kc), shape factor (Kf), and circularity index (IC). The characteristics of the drainage network, which consists in the survey of the following parameters: length of the main river (Lc), total length of the channels (Lt), basin order, drainage density (Dd), hydrographic density (Dh), sinuosity index (Is), and average runoff length (

A comparison of metrics for quantifying cranial suture complexity

Cranial sutures play critical roles in facilitating postnatal skull development and function. The diversity of function is reflected in the highly variable suture morphology and complexity. Suture complexity has seldom been studied, resulting in little consensus on the most appropriate approach for comparative, quantitative analyses. Here, we provide the first comprehensive comparison of current approaches for quantifying suture morphology, using a wide range of two-dimensional suture outlines across extinct and extant mammals ( n = 79). Five complexity metrics (sinuosity index (SI), suture complexity index (SCI), fractal dimension (FD) box counting, FD madogram and a windowed short-time Fourier transform with power spectrum density (PSD) calculation) were compared with each other and with the shape variation in the dataset. Analyses of suture shape demonstrate that the primary axis of variation captured attributes other than complexity, supporting the use of a complexity metric over raw shape data for sutural complexity analyses. Each approach captured different aspects of complexity. PSD successfully discriminates different sutural features, such as looping patterns and interdigitation amplitude and number, while SCI best-captured variation in interdigitation number alone. Therefore, future studies should consider the relevant attributes for their question when selecting a metric for comparative analysis of suture variation, function and evolution.

ZAB RIVER (IRAQ) SINUOSITY AND MEANDERING ANALYSIS BASED ON THE REMOTE SENSING DATA

This work studies the meandering and change of paths along the Zab River in Iraq. Landsat-5 TM, Landsat-7 ETM+ and Landsat-8 (2-sets) images were acquired from the years 1989, 1999, 2015 and 2019, respectively, which were used together with Remote sensing and Geographic Information Systems (GIS) techniques to study the changes. To determine the river/stream shape, the Sinuosity Index was calculated to classify Zab River segments into either the straight, sinuous or meandering class. Our findings via image analysis show coarse river migration and that most river segments fall into the two classes of sinuous and meander. In addition, it seems that the east bank of the Zab River region of the basin has extremely shifted where the river passes near the Kirkuk governorate.

Investigate the Influence of Hydraulic Factors on Landslide Susceptibility of Riverbank for the Chenyulan watershed

<p>The riverbank landslide is considered as the major sediment supply in the watershed. It mostly due to the river flows erode the foot of the riverbank, which makes the slope unstable. This study focused on the watershed susceptibility analysis of the riverbank landslide in the Chenyulan watershed. The Logistic regression method was used to establish the landslide susceptibility model not only with the topography, geological and anthropic factors, but also with the hydraulic factors including the hydraulic Sinuosity index, channel gradient, and concave-or-convex bank. The study areas were classified into four regions, according to the river-bed slope and confluence of rivers. The effects of the hydraulic factors on the model results were investigated. In the upstream region with mild topographic slope, the landslides were found to be dominated by the topography factors. The area under the curve (AUC) value of the model was 74.2%. In the upstream region with steep topographic slope, the steep hillslopes and the channel erosion of the concave bank produced a high weight of concave-or-convex bank in the model. The developed model exhibited an increased AUC value of 77.2%. In the downstream region, the lateral erosion of the channel increased the weights of hydraulic sinuosity index and channel gradient in the model. The developed model exhibited high area under the curve (AUC) value of 89.2%. The hydraulic factors increased the predictive performance of the model considerably.</p><p>Keyword: Riverbank, Hydraulic factors, Logistic regression</p>

Development of a processing chain of multispectral Sentinel–2 data to extract meandering river courses for geomorphometric analysis in Central Amazonia Region

<p>Freely-meandering rivers are sensitive indicators of neotectonic activity that is otherwise difficult to detect in low-relief areas. In this study sinuosity analysis has been carried out on 20 main rivers and tributaries of Central Amazonia Region as an aid for localization of river channel patterns influenced by on-going tectonic activity.</p><p>The main problem of such studies, however, the availability of accurate river channel data. For the Central Amazonia Region highly accurate dataset that has a good geographical coverage is hardly available: the datasets we found did not fulfill the accuracy criteria for our project.</p><p>Consequently, the first objective of this project was to develop a data processing method of high resolution satellite images which provides a quick and accurate way to digitize river sections of a large parts of the intracratonic sedimentary basin. Furthermore, this work aims to detect channel sinuosity changes that could indicate recent vertical crustal movements. To achieve this, the water courses were automatically digitized using Sentinel–2 data and classic sinuosity values were calculated using several window sizes. The distribution of sinuosity variations was analysed by classification and various representations of the calculated values like mapping, crossplots and sinuosity-spectrum.</p><p>As the visualization methods complement each other the variations in sinuosity values can be highlighted and verified in several aspects. The results compared to former neotectonic studies some significant sinuosity changes can be correlated to known faults. The mentioned sinuosity variations coincides with the location of NW–SE normal and thrust faults active since Pleistocene times and NE–SW Miocene normal faults supporting the idea that these structures may have been reactivated.</p><p>In conclusion, multi-window sinuosity index calculation applied to satellite data based digitized water courses is a useful tool for recognizing recent tectonic activity in large low-relief areas, such as Central Amazonia.</p>