Cartosat-1 Digital Elevation Model Research Articles

Space based Earth observation approach for exploring hydrocarbon prospects in an intracratonic rift basin – A study in north Cambay basin, Gujarat

In the present study, we carried out a conjugate analysis of Landsat-8 Operational Land Imager (OLI), Sentinel-2B Multi-Spectral Instrument (MSI), Advanced Land Observation Satellite Phased Array L-band SAR (ALOS PALSAR), and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data over a study area of northern Cambay Basin to delineate prospective areas for hydrocarbon exploration. In this regard, we utilized feature-oriented principal component (PC) images of Landsat OLI data, PC images of Sentinel-2B visible and near-infrared (VNIR)-short-wave infrared (SWIR) bands, thresholded Cartosat-1 Digital Elevation Model (DEM), and polarization image composite of ALOS PALSAR data to delineate geomorphic and lineament features in the study area. Most of the geomorphic features, such as scroll plain, gullies, elevated pediment, circular drainage anomalies, etc., indicate localized structural uplift. Geomorphic anomalies and lineaments, essential for identifying structural controls of near-surface hydrocarbon accumulation, were identified using enhanced satellite data. Geophysical anomalies derived from gravity datasets supplemented the presence and down-depth continuity of geological structures. Spectral profiles of calcrete-bearing soil samples were used to identify calcrete-rich zones in the optical remote sensing image data as a proxy owing to field evidence of close association of calcrete-rich soils with known subsurface hydrocarbon accumulations. Sub-pixel mapping algorithm Constrained Energy Minimization (CEM) applied to SWIR bands of ASTER data was used to delineate surface proxies of near-surface hydrocarbon seepage. Isopach maps of shallowest reservoir formations (Mid-/ Late Eocene) were used as indicators of favorable near-surface hydrocarbon accumulation.Earth observation-based geomorphic, lineament, and spectral anomalies were integrated with supplementary datasets, such as reservoir isopach and absorbed gas anomalies, as controls using the weighted summation method for quantitative deduction of the hydrocarbon potential map of the study area. The weights for input variables or parameters (geomorphic, spectral, geochemical, etc.) were inferred based on spatial associations of these anomalous units/variables with the existing oil & gas well locations. The identified potential map is in broad synergy with the field observations on localized uplift, geo-botanical anomalies, and calcrete-rich zones within the extent of high & moderate hydrocarbon potential areas.

Towards quantifying the relative tectonic activity in the Trans-Yamuna segment of NW Himalaya

Owing to the increased availability of high-resolution satellite data and the rapid development of Geographic Information System (GIS) technology, the mapping of active faults and quantification of tectonic activity in inaccessible regions has exceedingly improved. We examined the tectonic activity in the Trans-Yamuna region of the NW Himalaya using geomorphic indices derived from a Digital Elevation Model (DEM). In addition, this study evaluates the sensitivity of four space-borne Digital Elevation Models (DEMs) with respect to TAN DEM-X (TerraSAR-X add-on for Digital Elevation Measurements). The Cartosat DEM, generated with a spatial resolution of 5 meters using state-of-the-art methods, demonstrated a reliable representation of topography. Geomorphic indices such as Asymmetry Factor (AF), Transverse Topography (TT), Hypsometric Integral (HI), Valley Floor width (Vf), Stream-length gradient index (SL), and Normalised steepness index (ksn) were computed for 41 sub-watersheds to determine the degree of tectonic activity. We infer that majority of the region is tectonically active, with upliftment continuing to occur in the north of the Main Boundary Thrust (MBT). Furthermore, the existence of mapped active faults north of the MBT further substantiates the fact that strain release is not only concentrated in the frontal Himalaya, but is distributed over a broader area above the decollement.

Assessment of the geomorphic indices in relation to tectonics along selected sectors of Borpani River Basin, Assam using Cartosat DEM data

• A total of eleven geomorphic indices were studied in detail for the assessment of tectonic activity along Borpani River. • Results indicates satellite imageries based Geomorphic indices can witnesses tectonic influences. • Overall tectonic activity indicates classes - active, moderately active and less active zones in the study region. • On average, 23.86%, 29.54%, and 46.58% of the geomorphic indices falls in active, moderately active and low active classes. We studied geomorphic indices related to tectonics along the Borpani River using Cartosat 10 m spatial resolution Digital Elevation Model (DEM) data. A total of 11 geomorphic indices such as transverse topographic symmetry factor (Tt), drainage basin asymmetry (AF), valley floor width to valley height ratio (Vf), bifurcation ratio (Rb), hypsometric integral (HI), basin elongation ratio (Re), basin shape index (Bs), circularity ratio (Rc), drainage density (Dd), relief ratio (Rh), hypsometric curves (HC) were studied to access the tectonics along the river in selected locations. Five locations along the river were selected for detailed analysis (sub-basin I, II a, II b, III, and IV). Horton's (1945) scheme was adopted for watershed delineation, while stream ordering was performed using Strahler's (1964) method. The results infer that the sub-basins along the Borpani River are tectonically active. In the case of sub-basin I, 3 geomorphic indices out of 11 falls in the category of highly active, and 2, 1, 2, and 4 indices out of 11 falls in the category of highly active in the case of sub-basins II a, II b, III, and IV. Similarly, 4, 1, 3, 6, 1 and 4, 8, 7, 3, 6 indices fall under moderately active and low active classes in sub-basins I, II a, II b, III, and IV. On average, 23.86 %, 29.54%, and 46.58% of the geomorphic indices fall in the active, moderately active, and low active classes.

Morphometric evaluation of Ranikhola watershed in Sikkim, India using geospatial technique

Morphological parameters are linked with the hydrological behaviour of the watershed. It helps to understand different basin characteristics. Characterization of quantitative morphology and river basin analysis is the way to implement proper river basin planning and management of soil and water conservation measures. In the present study, Cartosat-1 Digital Elevation Model (DEM) was used in Geographic Information System (GIS) environment to determine the morphometric parameters (stream length, stream order, stream frequency, bifurcation ratio, form factor, drainage density, circulatory ratio, etc.) of the Ranikhola watershed of Sikkim state, India. The slope of a major portion of the watershed area was found to be less than 30% (42 km2) and has a drainage density of 0.585 km-1. The lower value of drainage density in the watershed indicates a relatively lower streams frequency over the watershed. The elongation ratio, form factor, and circulatory ratio were estimated as 0.665, 0.347, and 0.510, respectively, which indicate that the watershed is elongated in shape, having gentle slopes and long flow paths. The relief ratio for the watershed was estimated to be 0.187, which indicates the watershed has a low elevation difference, low runoff, and high groundwater potential. This kind of morphometric analysis is required for the watershed characterization and helps to understand the hydrogeological behavior of the watershed.

Hydrological modelling through SWAT over a Himalayan catchment using high-resolution geospatial inputs

The concerns of water availability have been increasing due to population explosion, rapid industrialization, and other anthropogenic activities. This urges for an accurate estimation of streamflow at the river basin scale, which is typically carried out by the application of rainfall-runoff models. Though numerous models exist in hydrology literature, their efficiency over the mountainous catchments is generally observed to be poor, mostly due to the lack of high-quality data over such regions. This study presents an application of the widely used soil and water assessment tool (SWAT)-based hydrological modelling using high-resolution geospatial inputs over the Tehri reservoir catchment (India) located in the lower Himalayan region. The Resourcesat-2 Linear Imaging Self-Scanning System (LISS)-IV imageries of land use/land cover (LULC) and the Cartosat-1 digital elevation model (DEM) are procured from National Remote Sensing Centre (NRSC), Indian Space Research Organization (ISRO), India. The LULC and DEM have a spatial resolution of 5.8 m and 2.5 m, respectively. SWAT model is applied for a duration of 12 years (2006-2017) with 2006, 2007-2013 and 2014-2017 as the warm-up, calibration and validation periods, respectively. The results reveal an excellent performance of the model in streamflow simulation. The efficacy measures viz., Nash–Sutcliffe efficiency (NSE) and Coefficient of determination (R2) are obtained to be 0.83 and 0.84, respectively. The information reported in this study will be helpful to the water resources engineers for hydrologic modelling over the mountainous catchments.

Dam Break Analysis using HEC-RAS: A Case Study of Karjan Dam

A dam is a structure constructed across river which stores water and supplies water for various purposes. Though the dams have many benefits, there is always a threat of dam break floods which are devastating in nature. Hence it becomes essential to analyze and simulate dam failure scenarios to understand the severity of dam break flood and identify areas under threat which helps in land use planning and developing emergency response plans. This study attempts to carry out dam break/breach analysis for the Karjan dam using a two-dimensional hydraulic model called Hydraulic Engineering Center’s River Analysis System (HEC-RAS). RAS-Mapper tool is used to extract river geometry data from the Cartosat-1 digital elevation model (DEM) and to generate the inundation map to identify the areas affected. The study involves the prediction of breach parameters, breach flood hydrograph, peak flow, flood arrival time, and generation of inundation maps. The dam break model is simulated for unsteady flow conditions using Probable Maximum Flood (PMF) corresponding to different failure scenarios. HEC-RAS tool is utilized to determine the breach outflow hydrograph and hydraulic conditions at critical downstream locations. The outcome will assist the local government in making proper planning and development decisions. Key Words: Arc-GIS, Dam break analysis, Karjan dam, Flood Inundation, HEC-RAS

GIS-based multi-criteria approach to delineate groundwater prospect zone and its sensitivity analysis

This study was aimed at delineating groundwater potential zones (GWPZ) using geo-spatial techniques for Ranchi district, Jharkhand (India). Data including Cartosat-1 digital elevation model (DEM), Landsat 8 satellite images, lithology, geology, soil, and water yield data were utilised in this study. The relative importance of multiple parameters including lithology, soil, slope, geology, rainfall, drainage density, and land use/land cover (LULC) that influence the availability of groundwater was determined subjectively. Analytical hierarchy process (AHP) along with pair-wise comparison decision theory was utilized to calculate the weights for each aforementioned parameter. The delineated GWPZ were categorized into four classes viz., very good zone (31.57%), good zone (45.43%), moderate zone (13.09%), and poor zone (8.53%). The sensitivity analysis indicated lithology and soil type as the most and least sensitive parameters, respectively influencing the presence of groundwater in the study area. Comparison between well discharge data and delineated GWPZ yielded a coefficient of determination (R2) of 0.59. This study contributes to identifying priority areas where appropriate water conservation programs as well as strategies for sustainable groundwater development can be implemented.

A Theoretical Analysis of Granulometry-Based Roughness Measures on Cartosat DEMs

The study of water bodies such as rivers is an important problem in the remote sensing community. A meaningful set of quantitative features reflecting the geophysical properties help us better understand the formation and evolution of rivers. Typically, river sub-basins are analyzed using Cartosat Digital Elevation Models (DEMs), obtained at regular time epochs. One of the useful geophysical features of a river sub-basin is that of a roughness measure on DEMs. However, to the best of our knowledge, there is not much literature available on theoretical analysis of roughness measures. In this article, we revisit the roughness measure on DEM data adapted from multiscale granulometries in mathematical morphology, namely <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">multiscale directional granulometric index (MDGI)</i> . This measure was classically used to obtain shape-size analysis in grayscale images. In earlier works, MDGIs were introduced to capture the characteristic surficial roughness of a river sub-basin along specific directions. Also, MDGIs can be efficiently computed and are known to be useful features for classification of river sub-basins. In this article, we ask the question <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">when does a MDGI fail to classify distinct DEMs?</i> We provide a theoretical analysis of a MDGI to answer this question. In particular, we identify nonrivial sufficient conditions on the structure of DEMs under which MDGIs cannot distinguish between distinct DEMs. These properties are illustrated with some fictitious DEMs. We also provide connections to a discrete derivative of volume of a DEM. Based on these connections, we provide intuition as to why a MDGI is considered a roughness measure. We empirically verify that MGDIs capture the topographical characteristics using the Lower-Indus, Wardha, and Barmer river sub-basins. We show that a simple decision tree based on MDGI features alone can successfully distinguish between sub-basins with a high accuracy. We obtain upto 94% accuracy while the baseline of random classifier is around 33.34%.

Dam break analysis using HEC-RAS and HEC-GeoRAS: A case study of Hidkal dam, Karnataka state, India

A dam is a structure constructed across river which stores water and supplies water for various purposes. Though the dams have many benefits, there is always a threat of dam break floods which are devastating in nature. Hence it becomes essential to analyze and simulate dam failure scenarios to understand the severity of dam break flood and identify areas under threat which helps in land use planning and developing emergency response plans. This study attempts to carry out dam break/breach analysis for the Hidkal dam using a one-dimensional hydraulic model called Hydraulic Engineering Center's River Analysis System (HEC-RAS). HEC-GeoRAS tool is used to extract river geometry data from the Cartosat-1 digital elevation model (DEM) and to generate the inundation map to identify the areas affected. The study involves the prediction of breach parameters, breach flood hydrograph, peak flow, flood arrival time, and generation of inundation maps. The dam break model is simulated for unsteady flow conditions using Probable Maximum Flood (PMF) corresponding to piping and overtopping failure scenarios. HEC-RAS tool is utilized to determine the breach outflow hydrograph and hydraulic conditions at critical downstream locations. Further, the breach outflow hydrographs are routed using dynamic flood wave routing. Further HEC-RAS model is simulated for breach parameters derived from five different empirical methods, and the results are compared. A sensitivity analysis is also carried out to know the variation of peak flow and maximum stage with respect to the breach parameters. The immediate downstream of the dam experience a peak flow of 72,085.45 m3/s and 78,454.82 m3/s and the corresponding inundation area of 75.224 km2 and 79.205 km2 due to piping failure and overtopping failure, respectively. Around twenty village located on the downstream of dam location gets affected due to flood produced by dam break. The analysis shows that overtopping failure is more severe than failure due to piping. The study shall further help authorities concerned to develop an emergency response plan and flood mitigation measures.

Mass balance and morphological evolution of the Dokriani Glacier, central Himalaya, India during 1999–2014

Glaciological mass balance (MB) is considered the most direct, undelayed and unfiltered response of the glaciers to climatic perturbations. However, it may inherit errors associated with stake under-representation, averaging over the entire glacier and human bias. Therefore, proper validation of glaciological MB with geodetic MB is highly recommended by the World Glacier Monitoring Service (WGMS). The present study focuses on the Dokriani Glacier, central Himalaya which is one of the bench-mark glaciers in the region and has glaciological MB records from 1993 to 2013 with intermittent gaps. In the present study, firstly the glaciological MB series is extended to 2014 i.e., field-based MB for one more year is computed and, to compare with it, the geodetic MB is computed for the 1999–2014 period using high resolution Cartosat-1 digital elevation model (DEM) and SRTM DEM. Finally, the study assesses the regional representation of the Dokriani Glacier in terms of MB and evaluates the influence of the MB regime on its morphological evolution. Results show that the average glaciological MB (−0.34 ± 0.2 m water equivalent (w.e.) y−1) is more negative than the geodetic MB (−0.23 ± 0.1 m w.e. y−1) for the 1999–2014 period. This is likely because of the partial representation of glacier margins in the glaciological MB, where melting is strikingly low owing to thick debris cover (>30 cm). In contrast, geodetic MB considers all marginal pixels leading to a comparatively low MB. A comparative assessment shows that the MB of Dokriani Glacier is less negative (possibly due to its huge accumulation area) than most other glacier-specific and regional MBs, restricting it to be a representative glacier in the region. Moreover, continuous negative MB has brought a peculiar change in the epiglacial morphology in the lower tongue of the glacier as differential debris thickness-induced differential melting has turned the glacier surface into a concave one. This concavity has led to development of a large (10–20 m deep) supraglacial channel which is expanding incessantly. The supraglacial channel is also connected with the snout wall and accelerates terminus disintegration. Given the total thickness of about 30–50 m in the lower glacier tongue, downwasting at its current pace, deepening/widening of supraglacial channel coupled with rapid terminus retreat may lead to the complete vanishing of the lower one km glacier tongue.

Estimation of flood influencing characteristics of watershed and their impact on flooding in data-scarce region

ABSTRACT The research is focused on the integrated use of satellite remote sensing, Geographic Information System (GIS), and extensive field observation techniques for a better understanding of the impacts of watershed characteristics on hydrological processes and floods. It aims to create a methodology for assessing flood hazards and risk on a regional and local scale so that protective measures can be designed. Floods have occurred in the study area for many years, causing serious damage to infrastructure and civic structures. The present study evaluates the linear, aerial and relief morphometric parameters using the Cartosat-1 digital elevation model (30 metres) along with the curve number for assessing the flood influencing characteristics of the Vishwamitri River’s sub-watersheds. The study prioritizes five sub-watersheds as high, medium, and low based on their flood influencing characteristics and compound value, as a result, needs the highest priority for flood mitigation measures. The sub-watersheds I and IV of Vishwamitri watershed have been categorized into high priority, sub-watersheds II and V into moderate priority, and sub-watershed III into low priority. The geologic stage of development and erosion proneness of the watershed is quantified by hypsometric integral bearing value as 0.04, indicating the landscape to be in monadnock phase in landscape evolution indicative of a marked old stage in the basin’s evolution. Moreover, the ability of the rain-on-grid model at the watershed scale to simulate flood events and predict flood-prone areas, considering multiple rain gauge data, which will facilitate more accurate flood inundation where ground-based observational data are unavailable is shown.

Uncertainty Assessment in Soil Erosion Modelling Using RUSLE, Multisource and Multiresolution DEMs

Soil erosion is a key concern for the environment and natural resources since it leads to a decline in-field productivity and soil quality, resulting in land degradation. In this study, assessment of uncertainty in soil erosion modelling of the Karso watershed, India, was carried out by employing the revised universal soil loss equation (RUSLE) and geospatial technologies to evaluate the effect of multi-source digital elevation models (DEMs) [Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Cartosat and Shuttle Radar Topography Mission (SRTM)] with resampled multi-resolution grids. The rainfall erosivity factor (R) was computed using the mean monthly Tropical Rainfall Measuring Mission rainfall estimates for 1998 to 2012. The slope length factor was derived using the ASTER and Cartosat DEMs at grid sizes of 30 m, 50 m, 100 m, 150 m, 200 m, and 250 m, and for the SRTM DEM at 100 m, 150 m, 200 m and 250 m resolutions for the Karso watershed, Jharkhand, India. Significant differences were obtained in the soil loss estimates across the different DEM sources and resampled grid sizes. The Cartosat DEM with a 200 m grid was found to estimate the soil loss the best out of all the DEM combinations considered. The Cartosat DEM proved to be more reliable than the ASTER and SRTM DEMs. The results indicated that the RUSLE is a scale-dependent model since the model estimates were affected not only by the DEM source but also by its resolution. The prediction of erosion potential by employing the multisource, multiresolution DEMs and the RUSLE helped to identify the soil erosion's spatial pattern within the watershed. The study provided an impact analysis of the uncertainties when selecting the multisource, multiresolution DEMs for soil erosion modelling.

Assessment of Soil Erosion Susceptibility Based on Morphometric and Landcover Analysis: A Case Study of Netravati River Basin, India

In this study, we assess the soil erosion susceptibility at the sub-basins scale using remote sensing data with the integration of the Geographical Information System (GIS) for the Netravati river basin in Western Ghats, India. The Cartosat digital elevation model was used for the calculation of morphometric parameters, and Landsat satellite images were used for land cover classification. The whole river basin was divided into five sub-basins for identifying the spatial variation of morphometric parameters and different land use categories. A weighted sum approach (WSA) was used for the ranking of each morphometric parameter and land use types. Then each sub-basin was assigned as very low, low, medium, high, and very high priority ranking. The final prioritization map based on the combined (morphometric and land cover) analysis showed erosion susceptibility is very high for sub-basin 4, high for sub-basin 2, medium for sub-basin 5, low for sub-basin 1, and very low for sub-basin 3. Further, the soil erosion susceptibility analysis has been done separately for morphometric and land cover at the sub-basins scale. The results of this study will be useful for the water resource manager and policymaker while considering the soil erosion-prone areas in the region, and the methodology can be adapted for other river basins.

A novel framework for seamless mosaic of Cartosat-1 DEM scenes

Digital elevation model (DEM) is used as a source of elevation data in wide range of applications. The applications involving larger area than an individual DEM scene often need a mosaic of DEM scenes. A simple stitching exhibits seams along the borders of DEM scenes in the mosaic output. The presence of seam lines varies with the number of scenes in an overlapping region and their overlap extents. The conventional feathering-based blend method, by virtue of the method itself, considers only two input scenes in an instance of the mosaic process. This method requires a suitable ordering of the input DEM scenes, especially in the overlapping regions containing more than two scenes. In this paper, we propose a framework that automatically handles the multiple overlapping regions and creates a seamless mosaic of Cartosat-1 DEM scenes for a given region of interest. We use a tree data structure to arrange input DEM scenes hierarchically based on their metadata. A traversal algorithm is devised to establish an order of precedence among the DEM scenes. This determines a unique input sequence of DEM scenes during mosaic process. In addition, two variants of feathering-based blend method are formulated to handle all possible cases of the overlapping regions. The experiments have been conducted on Cartosat-1 DEM scenes over 1°×1° region of interest. We analyze and compare our proposed methodology with average method and feathering-based blend method. We demonstrate that our framework exhibits a smooth transition of elevation values in the overlapping regions of the DEM mosaic output.

Evaluation of Sentinel 1–derived and open-access digital elevation model products in mountainous areas of Western Ghats, India

Digital elevation model, acquired and generated using manual field survey, stereo pairs, interferometric synthetic aperture radar (InSAR) and light detection and ranging techniques to characterize terrain topography, plays a dynamic role in geological and hydrological applications. Digital elevation models (DEMs) are subjected to comprise ineradicable faults owing to acquirement techniques and pre-processing methodologies. Experiencing non-uniform variation in accuracy, it is mandatory to assess the accuracy of DEMs before employing it for numerous purposes. Considering the fact, assessment of vertical and horizontal accuracies of open-access DEMs and InSAR-derived DEM is performed with Survey of India (SOI) toposheets as reference. Results concluded that Cartosat DEM and SRTM DEM of 30 m resolution with NRMSE as 10.5% and 10%, respectively, and PBIAS as − 0.3% and − 0.5% respectively highly correlated with the toposheet elevation when compared with other DEMs. Horizontal assessment of pixel offset concluded that Cartosat and SRTM DEM experience an offset of 0.1% along X-axis and 0.33% along Y-axis. Assessment of vertical accuracy and pixel offset concluded that CartoDEM and SRTM DEM are highly recommended for research purposes over Kodagu District, Karnataka, India. InSAR-derived DEM experiences massive variation and are not suggested over hilly terrains.

Comparison of different digital elevation models for drainage morphometric parameters: a case study from South India

With a plethora of digital elevation models (DEM) available for elevation extraction and catchment morphometric analysis, it is essential to compare and investigate their accuracy and parameter uncertainty derived from them. To serve that purpose, in this study, we have compared the DEMs of different resolution obtained from Shuttle Radar Topography Mission (SRTM), CARTOSAT, and topographic maps (1:25000) in terms of vertical accuracy and morphometric parameters. The investigation was performed on a sub-basin of Champavathi River which is located in Andhra Pradesh, the southern part of India. The vertical accuracy of the DEMs was estimated using elevation from about 1180 points obtained from the Differential Global Positioning System (DGPS) survey. The morphometric analysis showed that the basin is elongated with low relief ratio, mild/rolling slopes, and medium drainage density, and the results were comparable from different DEM sources indicating that most of the morphometric parameters were not significantly dependent on the scale and source of the DEM. Further, vertical accuracy estimation showed that the CARTOSAT DEMs (10 m and 30 m) have a lower root mean square error (4.53 m and 5.89 m) when compared with the SRTM DEMs (6.11 m and 7.19 m).

Application of new HEC-RAS version 5 for 1D hydrodynamic flood modeling with special reference through geospatial techniques: a case of River Purna at Navsari, Gujarat, India

Floods are among the extreme natural events which result in catastrophic damage to properties and adversely effects communities. To curb and manage the effects of such events, the decision-makers and disaster management authorities require dependable data in terms of flood depth, discharge, magnitude, and special datasets. The low lying areas of Navsari city was inundated in the floods of 2002 and 2003. This study aims to use the latest version of HEC-RAS for 1D hydrodynamic flood modelling of Purna river in Navasari city, Gujarat, India, with special reference to geospatial techniques. This study is aimed to demonstrate the geospatial analyzing capabilities of HEC-RAS v5. For the purpose of flood modeling, the river data such as bank lines, flow path lines, cross-section cut lines are extracted from Cartosat-1 DEM (Digital Elevation Model). Steady flow analysis is carried out for the simulation of a 1D hydrodynamic model. The outcome obtained from the model is in the form of water depth, which can be observed in the geospatial HEC-RAS mapper window. The flood depth maps for the 2002 and 2004 flood events are generated, which indicate that the low lying areas of Navsari city near Jalalpore and Viraval are susceptible to flooding when the discharge in the river exceeds 8836 m3/s. The accuracy of the model is calculated by comparing the simulated data with the observed data for the above-mentioned flood events. The results obtained from the 1D models are promising and accurate.

A novel method to improve vertical accuracy of CARTOSAT DEM using machine learning models

High quality, accessible Digital Elevation Model (DEM) datasets play a major role in monitoring the changes in the Earth’s surface. This study proposes a novel method to increase the vertical precision of CARTOSAT 10 m DEM by blending it with publicly available SRTM (Shuttle Radar Topography Mission) DEM using machine learning methods. Machine learning methods such as Genetic Programming (GP) and Artificial Neural Networks (ANN) are applied to the SRTM-1 DEM and the CARTOSAT DEM in India to generate DEM of improved vertical accuracy. Quantifiable results show that proposed approach improve the vertical accuracy, considering the reference as Ground control Points (GCPs) elevation from Differential Global Positioning System (DGPS) survey data. Significant improvements of 47 and 35% in RMSE are offered by generated DEMs compared to the SRTM-1 and CARTOSAT respectively.

Soil erosion and flood hazard zonation using morphometric and morphotectonic parameters in Upper Alaknanda river basin

In the present study, detailed morphometric, morphotectonic, statistical and hazard analyses have been carried out in the Upper Alaknanda river basin (UAB) located in Central Himalayas, Garhwal, India. The study area is bounded by the South Tibetan Detachment System in the north and by the Main Central Thrust in the south. The major river flowing in the area is Alaknanda which is a major tributary of river Ganga. The purpose of this study is to examine the influence of active tectonics, flood hazard, and soil erosion on the basis of morphotectonic and morphometric parameters using the Cartosat-1 Digital Elevation Model and ArcGIS software. The study area is divided into 10 sub-basins, where 50 morphometric and 6 morphotectonic parameters were calculated. Bifurcation ratio and stream frequency show that streams up to third order is having steep gradient and rolling through highly dichotomized terrain, due to which high overland flow and less groundwater recharge takes places, whereas drainage density clearly indicates the high flood possibility in the region. Morphotectonic parameters indicate relatively young to an early mature geological stage of sub-basins and tectonically active region. The statistical analysis of morphometric parameters is carried out by using correlation analysis, hierarchal cluster analysis, and principal component analysis. Based on their susceptibility to soil erosion, morphometry and landcover classification is carried out to prioritize the sub-basins of UAB. The combined morphometric, morphotectonic and statistical analysis indicates that the area is tectonically active and highly prone to flood, flood induced landslide and soil erosion. The case study of the 2013 flash flood event at three locations Benakuli, JP HEP and Pulna also confirms that the study area is hydro-geologically active to flood and flood induced hazards. The results obtained in this study are directly related to watershed management and hence soil erosion, tectonic activities and flash flood possibilities should be taken into consideration during future development in the area.

Accuracy validation and bias assessment for various multi-sensor open-source DEMs in part of the Karakoram region

ABSTRACT The present study evaluate horizontal and vertical accuracy of seven open-source digital elevation models (DEMs) having moderate-to-high resolutions viz. 30 m Shuttle Radar Topography Mission (SRTM1), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM), Advanced Land Observing Satellite World 3D (AW3D30), and Cartosat DEM (CartoDEM), 90 m TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X), 12.5 m terrain corrected Phased Array L-band Synthetic Aperture Radar (PALSAR) from Advanced Land Observing Satellite (ALOS) and 8 m High Mountain Asia (HMA) over the rugged mountainous terrain of the Karakoram region. Horizontal accuracy (specified in x and y) assessed by referring photogrammetrically generated master DEM from Cartosat-1 revealed AW3D30 as the most consistent DEM with a slight shift of +2.80 m and −4.89 m in x and y direction, respectively. However, vertical accuracy analysis showed that both HMA and AW3D30 DEMs are quite close to each other with MAE of 3.01 m and 3.46 m, RMSE of 5.6 m and 7.5 m, and NMAD of 4.09 m and 5.5 m, respectively. We also examined the influence of slope on DEM errors and associated elevation-dependent bias over non-glaciated surface which can be valuable input for geodetic mass balance estimations.