scholarly journals Impact of DEM Resolution and Spatial Scale: Analysis of Influence Factors and Parameters on Physically Based Distributed Model

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Hanchen Zhang ◽  
Zhijia Li ◽  
Muhammad Saifullah ◽  
Qiaoling Li ◽  
Xiao Li
Keyword(s):  
Influence Factors ◽  
Distributed Model ◽  
Small Scale ◽  
Simulation Accuracy ◽  
Digital Elevation ◽  
Physically Based ◽  
Simulation Results ◽  
Distributed Hydrological Models ◽  
Elevation Model ◽  
Sensitive Parameters

Physically based distributed hydrological models were used to describe small-scale hydrological information in detail. However, the sensitivity of the model to spatially varied parameters and inputs limits the accuracy for application. In this paper, relevant influence factors and sensitive parameters were analyzed to solve this problem. First, a set of digital elevation model (DEM) resolutions and channel thresholds were generated to extract the hydrological influence factors. Second, a numerical relationship between sensitive parameters and influence factors was established to define parameters reasonably. Next, the topographic index (TI) was computed to study the similarity. At last, simulation results were analyzed in two different ways: (1) to observe the change regularity of influence factors and sensitive parameters through the variation of DEM resolutions and channel thresholds and (2) to compare the simulation accuracy of the nested catchment, particularly in the subcatchments and interior grids. Increasing the grid size from 250 m to 1000 m, the TI increased from 9.08 to 11.16 and the Nash-Sutcliffe efficiency (NSE) decreased from 0.77 to 0.75. Utilizing the parameters calculated by the established relationship, the simulation results show the same NSE in the outlet and a better NSE in the simple subcatchment than the calculated interior grids.

scholarly journals Zero Watermarking for the TIN DEM Data Based on the Edge Length

2021 ◽  
Vol 10 (8) ◽  
pp. 559
Author(s):  
Qifei Zhou ◽  
Changqing Zhu ◽  
Na Ren
Keyword(s):  
Edge Length ◽  
Majority Voting ◽  
Data Simulation ◽  
Triangulated Irregular Network ◽  
Digital Elevation ◽  
Crucial Problem ◽  
Simulation Results ◽  
Elevation Model ◽  
Zero Watermarking ◽  
Voting Mechanism

How to keep the fidelity of the digital elevation model (DEM) data is a crucial problem in the current watermarking research, as the watermarked DEM data need to preserve their accuracy. We proposed a zero watermarking method for the triangulated irregular network (TIN) DEM data. It takes full advantage of the characteristics of the edge length in the TIN DEM data. First, the radio of the edge lengths is quantified to the watermark index, and then the comparison of the edge lengths is quantified to the watermark bit. Finally, the watermark is constructed by combing the watermark bits according to the watermark indices with the help of the majority voting mechanism. In the method, the TIN DEM data are only used to construct the watermark, not to be embedded by the watermark. Therefore, the data quality is preserved to the greatest extent. Experiments verify the theoretical achievements of this method and demonstrate the method is lossless to the TIN DEM data. Simulation results also show that the method has good robustness on translation, rotation, scaling, and cropping attacks.

scholarly journals Hydrologic analysis of a flood based on a new Digital Elevation Model

2015 ◽  
Vol XL-7/W4 ◽  
pp. 127-134 ◽  
Author(s):  
M. Nishio ◽  
M. Mori
Keyword(s):  
Digital Elevation Model ◽  
Spatial Resolution ◽  
Meteorological Data ◽  
Data Acquisition System ◽  
Hydrologic Processes ◽  
Hydrologic Analysis ◽  
Digital Elevation ◽  
Simulation Results ◽  
Typhoon Season ◽  
Elevation Model

These The present study aims to simulate the hydrologic processes of a flood, based on a new, highly accurate Digital Elevation Model (DEM). The DEM is provided by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) of Japan, and has a spatial resolution of five meters. It was generated by the new National Project in 2012. The Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) is used to simulate the hydrologic process of a flood of the Onga River in Iizuka City, Japan. A large flood event in the typhoon season in 2003 caused serious damage around the Iizuka City area. Precise records of rainfall data from the Automated Meteorological Data Acquisition System (AMeDAS) were input into the HEC-HMS. The estimated flood area of the simulation results by HEC-HMS was identical to the observed flood area. A watershed aggregation map is also generated by HEC-HMS around the Onga River.

scholarly journals Heterogeneidade da Rugosidade em Terrenos Complexos e Implicações para o Aproveitamento Eólico (Heterogeneity of Roughness in Complex Terrains and Implications for Wind Power)

2016 ◽  
Vol 9 (2) ◽  
pp. 546
Author(s):  
Thiago Lobão Cordeiro ◽  
Arcilan Trevenzoli Assireu ◽  
Ramon Moraes Freitas ◽  
Nandamudi Lankalapalli Vijaykumar ◽  
Reinaldo Roberto Rosa
Keyword(s):  
Wind Power ◽  
Roughness Length ◽  
Small Scale ◽  
Measuring Point ◽  
Wind Pattern ◽  
Displacement Height ◽  
Digital Elevation ◽  
Wind Profiles ◽  
Elevation Model ◽  
Plane Displacement

A demanda para a produção de energia renovável e de baixo impacto ambiental cresce a cada ano e, com isso, há também o aumento do interesse em turbinas eólicas de pequena escala a serem instaladas em relevos complexos que inclui áreas onde montanhas afetam o padrão de vento, como em grandes sistemas aquáticos localizados em regiões de planaltos. A influência da complexidade do relevo e da intensidade de turbulência foi investigada pela aplicação do método de Análise por Padrões de Gradientes em um modelo digital de elevação e uma série de dados histórica da direção e velocidade do vento. Os resultados indicaram que os padrões de fluxos são extremamente complexos e variam significativamente dependendo da direção do fluxo em sentido contrário. Esta variabilidade também torna difícil definir um plano zero de deslocamento ou um comprimento de rugosidade para um determinado ponto de medição, o que compromete a utilização do modelo de extrapolação vertical do vento baseado no coeficiente de rugosidade fixo.      ABSTRACT As the demand for environmentally friendly energy production grows, there is also an increased interest in small scale wind turbines located in more complex relief that includes areas where mountains affect the wind pattern, as in large inland aquatic system localized close to hills. Influence of complex relief on the turbulence intensity was investigated by means of time series of the wind direction and speed and digital elevation model. The results indicated that the flow patterns are highly complex and vary significantly depending on the direction of the oncoming flow. This variability also makes it difficult to define a general zero plane displacement height or a roughness length for a certain measuring point. The resulting consequence for the usual one-dimensional wind profiles models are then pointed out. Keywords: GPA. Roughness of the relief. Wind power.   

scholarly journals Assessing ice-cliff backwasting and its contribution to total ablation of debris-covered Miage glacier, Mont Blanc massif, Italy

2014 ◽  
Vol 60 (219) ◽  
pp. 3-13 ◽  
Author(s):  
T.D. Reid ◽  
B.W. Brock
Keyword(s):  
Field Measurements ◽  
Distributed Model ◽  
Short Term ◽  
Model Calculations ◽  
Digital Elevation ◽  
Debris Cover ◽  
Continuous Surface ◽  
Elevation Model ◽  
Miage Glacier ◽  
Mont Blanc Massif

AbstractContinuous surface debris cover strongly reduces the ablation of glaciers, but high melt rates may occur at ice cliffs that are too steep to hold debris. This study assesses the contribution of ice-cliff backwasting to total ablation of Miage glacier, Mont Blanc massif, Italy, in 2010 and 2011, based on field measurements, physical melt models and mapping of ice cliffs using a high-resolution (1 m) digital elevation model (DEM). Short-term model calculations closely match the measured melt rates. A model sensitivity analysis indicates that the effects of cliff slope and albedo are more important for ablation than enhanced longwave incidence from sun-warmed debris or reduced turbulent fluxes at sheltered cliff bases. Analysis of the DEM indicates that ice cliffs account for at most 1.3% of the 1 m pixels in the glacier’s debris-covered zone, but application of a distributed model indicates that ice cliffs account for ~7.4% of total ablation. We conclude that ice cliffs make an important contribution to the ablation of debris-covered glaciers, even when their spatial extent is very small.

Prediction of soil salinity risk by digital terrain modeling in the Canadian prairies

2000 ◽  
Vol 80 (3) ◽  
pp. 455-463 ◽  
Author(s):  
I. V. Florinsky ◽  
R. G. Eilers ◽  
G. W. Lelyk
Keyword(s):  
Soil Salinity ◽  
Risk Index ◽  
Small Scale ◽  
Canadian Prairies ◽  
Digital Terrain ◽  
Terrain Models ◽  
Digital Elevation ◽  
Soil Salinisation ◽  
Elevation Model ◽  
Digital Terrain Modeling

Soil salinisation is a typical problem for the Canadian prairies. At macro-topographic scale, build-up of salts occurs in depressions. However, this relationship is not displayed on existing small-scale maps of soil salinity. To improve these maps, one can use a concept of accumulation, transition and dissipation zones of the landsurface. The concept allows one to reveal depressions (topographically expressed accumulation zones) using digital models of horizontal and vertical curvatures, or accumulation and mean curvatures derived from a digital elevation model. We applied the concept of accumulation, transition and dissipation zones to improve an existing small-scale map of the salinity risk index for the prairies and adjacent areas. A comparison of the old and the improved maps demonstrated that once data on depressions have been taken into account, areas marked by salinity risk decreased significantly. We suggest that the method used may prevent an overestimation in predictions of soil cover degradation due to salinisation. The method used can also reveal saline areas linked with discharges of saline aquifers. This is because sites marked by high discharges of groundwater usually relate to sites of intensive fracturing of geological materials, which are closely associated with topographically expressed accumulation zones. Key words: Digital terrain models, topography, soil salinisation, mapping

Visibility Analysis of GNSS Satellites in Mountainous Area

2012 ◽  
Vol 588-589 ◽  
pp. 888-892
Author(s):  
Bo Zhang ◽  
Jing Zhao ◽  
Wen Wei Duan ◽  
Long Yang Yu
Keyword(s):  
Digital Elevation Model ◽  
The Other ◽  
Visible Range ◽  
Mountainous Area ◽  
Visibility Analysis ◽  
Other Hand ◽  
Digital Elevation ◽  
Novel Method ◽  
Simulation Results ◽  
Elevation Model

A novel method of analyzing the visibility of GNSS satellites in mountainous area is proposed by taking advantage of target area’s digital elevation model (DEM) data and GNSS almanac. The key point is calculating the obstacle elevation on the basis of target points’ visible range. Simulation results show that both different target points at the same time and same point at different time have different situation of visible satellites on the condition with or without obstacle. On the other hand, this method contributes lots to determine the distribution of pseudolites in mountainous area.

scholarly journals Modeling the Hydrological Characteristics of Hangar Watershed, Ethiopia

2020 ◽  
Author(s):  
Abdata Galata
Keyword(s):  
Goodness Of Fit ◽  
Assessment Tool ◽  
Swat Model ◽  
Integrated Water Resources Management ◽  
Water Balance Components ◽  
Warm Up ◽  
Hydrological Characteristics ◽  
Digital Elevation ◽  
Physically Based ◽  
Elevation Model

Modelling the hydrological characteristics of watershed is a method of understanding behavior and simulating the water balance components of watershed for planning and development of integrated water resources management. The soil and water assessment tool (SWAT) physically based hydrological modelling was used for modelling hydrologic characteristics of the Hangar watershed. The data used for this study were digital elevation model (DEM), land use land cover data, soil map, climatological and hydrological data. The model calibrated and validated using measured streamflow data of 13 years (1990-2002) and 9 years (2003-2011) respectively including warm-up period. The SWAT model performs well for both calibration (R2 = 0.87, NSE = 0.82 and PBIAS = +1.4) and validation (R2 = 0.89, NSE = 0.88 and PBIAS = +1.2). The sensitivity analysis, which was carried out using 18 SWAT parameters, identified the 13 most sensitive parameters controlling the output variable and with which goodness-of-fit was reached. The analysis results indicated that the watershed receives around, 9.6%, 59.9%, and 30.5% precipitation during dry, wet and short rainy seasons respectively. The received precipitation was lost by 9.6 %, 40.5%, and 41.3% in the form of evapotranspiration for each seasons correspondingly. The surface runoff contribution to the Watershed were 3.8%, and 79.2% during dry and wet seasons respectively, whereas, it contributes by 17.0% during short rainy seasons.

scholarly journals PEMODELAN DAERAH TANGKAPAN AIR WADUK KELILING DENGAN MODEL SWAT (Keliling Reservoir Catchment Area Modeling Using SWAT Model)

2015 ◽  
Vol 35 (01) ◽  
pp. 121
Author(s):  
Teuku Ferijal ◽  
Siti Mechram ◽  
Dewi Sri Jayanti ◽  
Purnama Satriyo
Keyword(s):  
Swat Model ◽  
Model Performance ◽  
Remote Sensing Data ◽  
Reservoir Volume ◽  
Digital Elevation ◽  
Data Volume ◽  
Elevation Model ◽  
Sensitive Parameters ◽  
Deviation Ratio ◽  
Standard Deviation Ratio

This study aimed to model watershed area of Keliling Reservoir using SWAT model. The reservoir is located in Aceh Besar District, Province of Aceh. The model was setup using 90m x 90m digital elevation model, land use data extracted from remote sensing data and soil characteristic obtained from laboratory analysis on soil samples. Model was calibrated using observed daily reservoir volume and the model performance was analyzed using RMSE-observations standard deviation ratio (RSR), Nash-Sutcliffe efficiency (NSE) and percent bias (PBIAS). The model delineated the study area into 3,448 Ha having 13 subwatersheds and 76 land units (HRUs). The watershed is mostly covered by forest (53%) and grassland (31%). The analysis revealed the 10 most sensitive parameters i.e. GW_DELAY, CN2, REVAPMN, ALPHA_BF, SOL_AWC, GW_REVAP, GWQMN, CH_K2 and ESCO. Model performances were categorized into very good for monthly reservoir volume with ENS 0.95, RSR 0.23, and PBIAS 2.97. The model performance decreased when it used to analyze daily reservoir inflow with ENS 0.55, RSR 0.67, and PBIAS 3.46.Keywords: Keliling Reservoir, SWAT, Watershed ABSTRAKPenelitian ini bertujuan untuk untuk memodelkan daerah tangkapan air Waduk Keliling dengan menggunakan Model SWAT. Waduk Keliling terletak di Kabupaten Aceh Besar, Propinsi Aceh. Dalam penelitian ini Model SWAT dikembangkan berdasarkan data digital elevasi model resolusi 90 m x90 m, tata guna lahan yang diperoleh dari intepretasi citra satelit dan data soil dari hasil analisa sampel tanah yang diperoleh di daerah penelitian. Model dikalibrasi dengan data volume waduk dan kinerja model dianalisa menggunakan parameter rasio akar rata-rata kuadrat error dan standard deviasi observasi (RSR), efesiensi Nash-Sutcliffe (NSE) dan persentase bias (PBIAS). Hasil deleniasi untuk daerah penelitian menghasilkan suatu DAS dengan luas 3,448 Ha dan memiliki 13 Sub DAS yang dikelompokkan menjadi 76 unit lahan. Sebagian besar wilayah study ditutupi oleh hutan (53%), dan pandang rumput (31%). Hasil analisa menunjukkan bahwa 10 parameter model yang sangat mempengaruhi debit adalah GW_DELAY, CN2, REVAPMN, ALPHA_BF, SOL_AWC, GW_REVAP, GWQMN, CH_K2 dan ESCO. Kinerja model sangat baik dalam memprediksikan volume tampungan waduk bulanan dengan nilai ENS 0,95, RSR 0,23, dan PBIAS 2,97. Namun, kinerja model menurun ketika mensimulasikan debit inflow harian dengan nilai-nilai ENS 0,55, RSR 0,67, dan PBIAS 3,46.Kata kunci: Waduk Keliling, SWAT, Daerah Tangkapan Air

scholarly journals Small scale contractional-extensional structures and morphotectonics along the fault traces of Izmit-Cocaeli (Turkey) 1999 earthquake

2001 ◽  
Vol 34 (1) ◽  
pp. 345 ◽  
Author(s):  
Z. TUTKUN ◽  
S. PAVLIDES
Keyword(s):  
Strike Slip ◽  
Small Scale ◽  
North Anatolian Fault Zone ◽  
Epicentral Area ◽  
The North ◽  
Digital Elevation ◽  
Earthquake Ruptures ◽  
Recent Sediments ◽  
Elevation Model ◽  
Extensional Structures

The Mw=7.4 Izmit (Kocaeli) earthquake of August 17, 1999 (Turkey) ruptured 100 km at least surface faults on land along the northwestern branch of the North Anatolian Fault Zone (NAFZ). Although the preexisting structures of NAFZ has been divided into segments, showing stepover and pull apart geometry, the earthquake ruptures are generally linear, E-W striking (N80°-100°), right-lateral. In small scale and on the recent sediments they show very typical strike-slip displacements (2 to 5m), pop-ups and pressure ridges (N 40- 70°), Ρ (N80°), R (N100-1100) and R' (~N350°) Riedel shears, extensional cracks (N115°-135°), restraining and releasing bends and small pull apart structures. In the epicentral area (Gölcük-Tepetarla) the seismic ruptures did not follow any known or previously mapped fault, but the morphology and the Digital Elevation Model (DEM) show typical and recognizable paleo-earthquake features. That is elongated valleys, shutter ridges, high angle slopes, scarplets, stream offset; while trenching tectonostratigraphy indicate palaeo sag-ponds (clayly deposits) and palaeo liquefaction (C14 dating-Holocene-historical deposits 200 to 11,000 yr. BP).

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