scholarly journals Uncertainties associated with digital elevation models for hydrologic applications: a review

2007 ◽  
Vol 11 (4) ◽  
pp. 1481-1500 ◽  
Author(s):  
S. P. Wechsler
Keyword(s):  
Digital Elevation Models ◽  
Grid Cell ◽  
Surface Flow ◽  
Distributed Parameter ◽  
Hydrologic Models ◽  
Current State ◽  
Digital Elevation ◽  
Terrain Parameters ◽  
State Of Research ◽  
Dem Uncertainty

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.

scholarly journals Uncertainties associated with digital elevation models for hydrologic applications: a review

2006 ◽  
Vol 3 (4) ◽  
pp. 2343-2384 ◽  
Author(s):  
S. Wechsler
Keyword(s):  
Digital Elevation Models ◽  
Grid Cell ◽  
Surface Flow ◽  
Distributed Parameter ◽  
Hydrologic Models ◽  
Current State ◽  
Digital Elevation ◽  
Terrain Parameters ◽  
State Of Research ◽  
Dem Uncertainty

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.

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
Keyword(s):  
Surface Flow ◽  
Model Parameters ◽  
Gis Technology ◽  
Hydrologic Models ◽  
Digital Elevation ◽  
Elevation Data ◽  
Terrain Parameters ◽  
The Relationship ◽  
Hydrological Parameter

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.  

scholarly journals TERRAIN: A computer program to process digital elevation models for modeling surface flow

1995 ◽  
Author(s):  
P.M. Schwartz ◽  
D.A. Levine ◽  
C.T. Hunsaker ◽  
S.P. Timmins
Keyword(s):  
Computer Program ◽  
Digital Elevation Models ◽  
Surface Flow ◽  
Digital Elevation

scholarly journals An effective depression filling algorithm for DEM-based 2-dimensional surface flow modelling

2012 ◽  
Vol 9 (9) ◽  
pp. 10011-10051
Author(s):  
D. Zhu ◽  
Q. Ren ◽  
Y. Xuan ◽  
Y. Chen ◽  
I. Cluckie
Keyword(s):  
Surface Runoff ◽  
Land Surface ◽  
Overland Flow ◽  
Digital Elevation Models ◽  
Surface Flow ◽  
Runoff Simulation ◽  
Flow Estimation ◽  
Flow Modelling ◽  
Digital Elevation ◽  
South East England

Abstract. The surface runoff process in fluvial/pluvial flood modelling is often simulated employing a two-dimensional (2-D) diffusive wave approximation to described by grid based digital elevation models (DEMs). However, a serious problem of this approach may arise when using a 2-D surface flow model which exchanges flows through adjacent cells, or conventional rink removal algorithms which also allow flow to be exchanged along diagonal directions, due to the existence of artificial depression in DEMs. This study firstly analyses the two types of depressions in DEMs and reviews the current depression filling algorithms with a medium sized basin in South-East England, the Upper Medway Catchment (220 km2) used to demonstrate the depression issue in 2-D surface runoff simulation by MIKE SHE with different DEM resolutions (50 m, 100 m and 200 m). An alternative depression-filling algorithm for 2-D overland flow modelling is developed and evaluated by comparing the simulated flows at the outlet of the catchment. This result suggests that the depression estimates at different grid resolution of DEM highly influences overland flow estimation and the new depression filling algorithm is shown to be effective in tackling this issue when comparing simulations in sink-dominated and sink-free digital elevation models, especially for depressions in relatively flat areas on digital land surface models.

scholarly journals A Hybrid Breaching-Filling method for sink removal adapted to parallel hydrological simulations

2021 ◽  
Author(s):  
sleimane hariri ◽  
Jens Gustedt ◽  
Sylvain Weill ◽  
Isabelle Charpentier
Keyword(s):  
Finite Element ◽  
Hybrid Method ◽  
Digital Elevation Models ◽  
Mixed Finite Element ◽  
Surface Flow ◽  
Army Corps ◽  
Engineering Structures ◽  
Flat Area ◽  
Digital Elevation ◽  
The Impact

<p>Digital Elevation Models (DEMs) are approximations used for hydrological simulations and flood mapping. Usually, DEMs have sinks corresponding to actual landscape depressions and/or engineered structures such as bridges, road embankments, overhangs, dams... over or near to water bodies. These sinks often result from interpolation errors or measurement inaccuracies. Regardless of the source, sinks usually cause issues in hydrological simulations.</p><p>Classical filling and breaching methods have shown performance limitations. On one hand, a breaching method cannot deal with big sinks such as sinkholes and lakes in a fair manner as it may yield a long and deeply incised breach channel (lindsay 2016) . On the other hand, even though favored among practitioners, filling a sink may yield a flat area whose altitude is the same as its outlet. Therefore, hybrid methods combining breaching and filling were introduced. Lindsay (2016) presented a hybrid method called “Selective breaching” where a threshold sink depth is defined. As noted in Martz and Garbrecht (1999), a flat area near to the drainage basin outlet impacts the computation of flow direction and the subsequent hydrological simulation.</p><p>A watershed partition into hydrological sub-units, e.g. (Hariri 2019)  allows for the parallelization of hydrological simulations. However, the larger the number of drainage basins and outlets, the more opportunities of having flat areas near outlets are met.</p><p>As an automatic mitigation, we propose a hybrid method blending a carved DEM and a filled DEM based on the distance to the outlet to take advantage of both methods.</p><p>The impact of the different methods to deal with sinks are evaluated for the Moderbach watershed (89 km², Région Grand-Est, France) chosen for its numerous engineering structures (5 big reservoirs, 6 large dams, 3 flood detention areas, roads and highway) comparing the results produced by a mixed-hybrid finite element code for surface flow simulation (Younes 1999) and HEC-RAS (Brunner 1994). The results show that the hybrid method we proposed overcomes the limitations of the classic filling and breaching and it is well adapted for parallel computing.</p><p> </p><p> </p><p>Bibliography</p><p>Brunner GW. HEC river analysis system (HEC-RAS). US Army Corps of Engineers, Hydrologic Engineering Center. 1994.</p><p>Hariri S, Weill S, Gustedt J, Charpentier I. Pairing GIS and distributed hydrological models using Matlab 2. CAJG - 2nd Conference of the Arabian Journal of Geosiences. 2019 Nov.</p><p>Lindsay JB. Efficient hybrid breaching‐filling sink removal methods for flow path enforcement in digital elevation models. Hydrological Processes. 2016 Mar 15;30(6):846-57.</p><p>Martz LW, Garbrecht J. An outlet breaching algorithm for the treatment of closed depressions in a raster DEM. Computers & Geosciences. 1999 Aug 1;25(7):835-44.</p><p>Younes A, Mose R, Ackerer P, Chavent G. A new formulation of the mixed finite element method for solving elliptic and parabolic PDE with triangular elements. Journal of Computational Physics. 1999 Feb 10;149(1):148-67.</p>

Culturally Responsive Pedagogy in Mathematics

2020 ◽  
Vol 2 ◽  
pp. 145-158
Author(s):  
Kenta Nagasawa
Keyword(s):  
Professional Development ◽  
Teacher Education ◽  
Culturally Responsive ◽  
Latino Students ◽  
Culturally Responsive Pedagogy ◽  
Mathematics Teacher Education ◽  
Development Program ◽  
Current State ◽  
Responsive Pedagogy ◽  
State Of Research

Purpose: This paper is a thematic literature review to examine the current state of research about Culturally Responsive Pedagogy in mathematics. The main themes are students’ perception, teacher education for pre-service teacher and professional development for teachers. Research methods/ approach: Literature was collected from Eric, which is a research engine of the education field. Also, Google Scholar is used to find articles of major scholars introduced by Dr. Rich Milner, who is the instructor of this course. Findings: Students faced microaggressions in mathematics class, which discouraged them to learn mathematics. The effect of teacher education was inconsistent in terms of the awareness of culturally responsive pedagogy and lesson plans. Research of professional development mentioned that mathematics was cultural. Implications for research and practice: It is more interesting to conduct long term or follow-up research to find the teacher’s practice after a taking professional development program. Also, it is critical to expand research scope besides African American and Latino students. Finally, evidence-based research is needed to change the political situation. Keywords: culturally responsive teaching, mathematics, teacher education, professional development, student’s perception

Digital Elevation Models

10.1596/34445 ◽  
2020 ◽  
Author(s):  
Louise Croneborg ◽  
Keiko Saito ◽  
Michel Matera ◽  
Don McKeown ◽  
Jan van Aardt
Keyword(s):  
Digital Elevation Models ◽  
Digital Elevation
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