scholarly journals Study of Hydrological Parameter with Respect to DEM Using GIS & RS in Nelliampathy Hill, Kerala

2018 ◽  
Vol 7 (3.10) ◽  
pp. 125
Author(s):  
T Subramani ◽  
K A.Niasi

Digital elevation models (DEMs) represent the total topography, surface flow is one of the more important data sources for deriving variables used by numerous hydrologic models. A lot of research has been directed to address vulnerability related with error in digital height models (DEMs) and the spread of blunder to determined terrain parameters. This audit unites a discourse of research in major topical regions identified with DEM vulnerability that influence the utilization of DEMs for hydrologic applications. The work is to give some understanding into the characterization of elevation data quality and the relationship amongst topography and water assets models. A key characteristic of circulated displaying is the spatially factor portrayal of the watershed as far as topography, vegetative, or land use/cover, soils and impenetrable territories and the subordinate model parameters that represent the hydrologic procedures of infiltration, evapotranspiration, and runoff. In our study, application of DEM and deriving hydrological parameters using remote sensing and GIS technology at Nelliampathy hill, Kerala.  

2006 ◽  
Vol 3 (4) ◽  
pp. 2343-2384 ◽  
Author(s):  
S. Wechsler

Abstract. Digital elevation models (DEMs) represent the topography that drives surface flow and are arguably one of the more important data sources for deriving variables used by numerous hydrologic models. A considerable amount of research has been conducted to address uncertainty associated with error in digital elevation models (DEMs) and the propagation of error to derived terrain parameters. This review brings together a discussion of research in fundamental topical areas related to DEM uncertainty that affect the use of DEMs for hydrologic applications. These areas include: (a) DEM error; (b) topographic parameters frequently derived from DEMs and the associated algorithms used to derive these parameters; (c) the influence of DEM scale as imposed by grid cell resolution; (d) DEM interpolation; and (e) terrain surface modification used to generate hydrologically-viable DEM surfaces. Each of these topical areas contributes to DEM uncertainty and may potentially influence results of distributed parameter hydrologic models that rely on DEMs for the derivation of input parameters. The current state of research on methods developed to quantify DEM uncertainty is reviewed. Based on this review, implications of DEM uncertainty and suggestions for the GIS research and user communities emerge.


2007 ◽  
Vol 11 (4) ◽  
pp. 1481-1500 ◽  
Author(s):  
S. P. Wechsler

Abstract. Digital elevation models (DEMs) represent the topography that drives surface flow and are arguably one of the more important data sources for deriving variables used by numerous hydrologic models. A considerable amount of research has been conducted to address uncertainty associated with error in digital elevation models (DEMs) and the propagation of error to derived terrain parameters. This review brings together a discussion of research in fundamental topical areas related to DEM uncertainty that affect the use of DEMs for hydrologic applications. These areas include: (a) DEM error; (b) topographic parameters frequently derived from DEMs and the associated algorithms used to derive these parameters; (c) the influence of DEM scale as imposed by grid cell resolution; (d) DEM interpolation; and (e) terrain surface modification used to generate hydrologically-viable DEM surfaces. Each of these topical areas contributes to DEM uncertainty and may potentially influence results of distributed parameter hydrologic models that rely on DEMs for the derivation of input parameters. The current state of research on methods developed to quantify DEM uncertainty is reviewed. Based on this review, implications of DEM uncertainty and suggestions for the GIS research and user communities are offered.


2016 ◽  
Vol 9 (1) ◽  
pp. 200 ◽  
Author(s):  
Alisson Cesar Da Cunha Souza ◽  
Márcio Luiz Da Silva

A identificação e mapeamento dos solos servem como subsidio para planejamentos agrícolas, levantamentos do uso da terra, estudos de terras para irrigação, estudos de preservação, análise e recuperação ambientais, predição de desastres naturais como o monitoramento de processos erosivos, dentre outros. Nesse sentido, os levantamentos e avaliações de solo, para fins agrícolas ou não, ganham importância, pois através deles é possível conhecer as propriedades desse recurso natural, permitindo sua utilização de forma consciente e adequada. O uso de sistemas de informações geográficas tem introduzido novos métodos para o levantamento e mapeamento de solos, por meio de modelagens, a partir da utilização de mapas temáticos básicos e modelos numéricos de terreno ou modelos digitais de elevação, que possibilitam, principalmente, a compreensão das relações entre a paisagem e as classes de solo. Assim, o objetivo deste trabalho foi a realização do levantamento e mapeamento dos solos do município de Inconfidentes - MG, utilizando técnicas de geoprocessamento, e a classificação pedológica até o quarto nível categórico através da generalização, a partir da descrição morfológica e determinações analíticas de perfis de solos representativos. Foi realizada a caracterização da área de estudos, a aquisição e tratamento de dados cartográficos. A descrição morfológica dos perfis foi realizada em pontos previamente definidos, representativos das distintas classes de solo do município. As análises físico-químicas foram realizadas em todas as amostras dos horizontes dos perfis de solos coletados em campo. A generalização do levantamento de solos foi elaborada através do processamento dos dados cartográficos e obtidos em campo, com a utilização do software ArGIS 9.3. O mapeamento pedológico do município foi então o resultado da integração e correlação dos dados altimétricos, da declividade, da rede de drenagem, do canal fluvial, do relevo e da litologia, associados com a caracterização feita em campo e as determinações analíticas. Como resultado, foi possível mapear as áreas de ocorrência de Latossolos, Gleissolos e Cambissolos, as três ordens de solos mais representativos do município, classificando-os até o quarto nível categórico. O uso das ferramentas de geotecnologia se mostrou muito útil para a caracterização das classes pedológicas e posterior generalização, uma vez que através delas foi possível inferir as condições ambientais de formação dos solos e integrá-los com dados de campo e análises laboratoriais.  ABSTRACT The identification and mapping of soils serve as subsidy for agricultural planning, land use surveys, land studies for irrigation, preservation studies, environmental analysis and recovery, prediction of natural disasters such as monitoring erosion, among others. In this sense, soil surveys and assessments, for agricultural purposes or not, become important because through them you can know the properties of this natural resource, allowing its use consciously and appropriately. The use of geographic information systems has introduced new methods to survey and soil mapping, through modeling, from the use of basic thematic maps and numerical terrain models and digital elevation models, which enable, especially, understanding the relationship between the landscape and the soil classes. The objective of this work was the completion of the survey and mapping of soils of city of Inconfidentes - MG, using geoprocessing techniques, and the pedological classification until the fourth categorical level by generalising from the morphological description and analytical profiles determinations representative soil. It was carried out to characterize their field of study, the acquisition and processing of cartographic data. The morphological description of the profiles was held in fixed locations, representative of the different soil classes of the municipality. The physicochemical analyzes were performed on all samples from the horizons of soil profiles collected in the field. Widespread soil survey was prepared by processing the cartographic data obtained in the field and, with the use of ArGIS 9.3 software. The pedological mapping of the municipality was then the result of the integration and correlation of altimetry data, the slope, the drainage network, the river channel, relief and lithology associated with the characterization made in the field and the analytical determinations. As a result, it was possible to map the areas of occurrence of Ferrasols, Cambisols and Gleysols, the three most representative soils of the municipality orders, sorting them until the fourth categorical level. The use of geotechnology tools proved very useful for the characterization of soil classes and subsequent generalization, since through them it was possible to infer the environmental conditions of soil formation and integrate them with field data and laboratory analysis. Keywords: Cambisols, Gleysols, Ferrasols, classification, hillslope.


Author(s):  
F. Betz ◽  
M. Lauermann ◽  
B. Cyffka

In recent years, fluvial geomorphology included a range of new technologies for the characterization of riverine landscapes in the pool of methods. LIDAR, the analysis of drone imagery or satellite remote sensing improved the ability to analyze river systems in manifold ways. However, the high demand for (often expensive) data and processing skills limit the application commonly to smaller study reaches or to regions where data is already available. In contrast, a range of conceptual frameworks for the geomorphological characterization of river systems highlights the relevance of integrating the catchment scale context. Against this background, virtual globes such as Google Earth are cost-efficient alternatives as they make high resolution satellite imagery available almost worldwide. Merging the information mapped from virtual globes with digital elevation data allows the interpretation of riverscape attributes in the context of the longitudinal profile. In our study, we present the geomorphological mapping of the more than 600 km long Naryn River in Kyrgyzstan based on different virtual globes and the SRTM-1 digital elevation model. The experience from this mapping exercise suggests that the combination of virtual globe imagery and elevation data is a powerful and cost-efficient approach for river research and application in the context of data-scarce river corridors.


Author(s):  
Axel P. Belemtougri ◽  
Agnès Ducharne ◽  
Harouna Karambiri

Abstract. In many continental databases representing rivers across Africa, information on rivers characteristics (length, width, intermittent or perennial) is often incomplete, and small streams are largely underrepresented. Fortunately, the use of topographic information from digital elevation models (DEMs) provides an opportunity to have more detailed information on rivers, particularly small streams in broad areas. A common approach to extract streams from DEM is to consider as a stream all DEM cells that drain at least a certain upstream surface, commonly known as the minimum contributing area (Amin). This parameter (Amin) is generally defined uniformly over large areas and this independently of the very variable climate and landscape conditions so that the generated streams have a rather uniform spatial distribution. To address this issue, using a 3′′ (approx. 90 m × 90 m) DEM of Burkina Faso, the relationship between Amin and the observed drainage density (Ddobs) was established with satisfactory performance (r2=0.86). In ongoing work, the functional relationship between the observed drainage densities (Ddobs) and environmental variables (lithology, climate, geology, vegetation cover) should allow for the establishment of the relationships between Amin and the environmental variables. This relationship allows for spatially variable Amin values depending on landscape characteristics. Before extracting river networks in Africa, the next step will be to validate or update these relationships in several countries.


2020 ◽  
Vol 63 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Stephanie A. Borrie ◽  
Tyson S. Barrett ◽  
Julie M. Liss ◽  
Visar Berisha

Purpose Despite the import of conversational entrainment to successful spoken dialogue, the systematic characterization of this behavioral syncing phenomenon represents a critical gap in the field of speech pathology. The goal of this study was to acoustically characterize conversational entrainment in the context of dysarthria using a multidimensional approach previously validated in healthy populations (healthy conversations; Borrie, Barrett, Willi, & Berisha, 2019 ). Method A large corpus of goal-oriented conversations between participants with dysarthria and healthy participants (disordered conversations) was elicited using a “spot the difference” task. Expert clinical assessment of entrainment and a measure of conversational success (communicative efficiency) was obtained for each of the audio-recorded conversations. Conversational entrainment of acoustic features representing rhythmic, articulatory, and phonatory dimensions of speech was identified using cross-recurrence quantification analysis with clinically informed model parameters and validated with a sham condition involving conversational participants who did not converse with one another. The relationship between conversational entrainment and communicative efficiency was examined. Results Acoustic evidence of entrainment was observed in phonatory, but not rhythmic and articulatory, behavior, a finding that differs from healthy conversations in which entrainment was observed in all speech signal dimensions. This result, that disordered conversations showed less acoustic entrainment than healthy conversations, is corroborated by clinical assessment of entrainment in which the disordered conversations were rated, overall, as being less in sync than healthy conversations. Furthermore, acoustic entrainment was predictive of communicative efficiency, corroborated by a relationship between clinical assessment and the same outcome measure. Conclusions The findings confirm our hypothesis that the pathological speech production parameters of dysarthria disrupt the seemingly ubiquitous phenomenon of conversational entrainment, thus advancing entrainment deficits as an important variable in dysarthria, one that may have causative effects on the success of everyday communication. Results further reveal that while this approach provides a broad overview, methodologies for characterizing conversational entrainment in dysarthria must continue to be developed and refined, with a focus on clinical utility. Supplemental Material https://osf.io/ktg5q


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