scholarly journals Spatial variation of channel head curvature in small mountainous watersheds

2019 ◽  
Vol 50 (5) ◽  
pp. 1251-1266
Author(s):  
Jian Wu ◽  
Lei Ye ◽  
Chenchen Wu ◽  
Qingrui Chang ◽  
Zhuohang Xin ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Distributions ◽  
Nonparametric Method ◽  
Channel Network ◽  
Contour Lines ◽  
Digital Elevation ◽  
Topographic Attributes ◽  
Mountainous Watersheds ◽  
Realistic Topography ◽  
Contour Curvature

Abstract High-resolution digital elevation models (DEMs) offer opportunities for channel network extraction due to its representation of realistic topography. Channels are generally surrounded by well-defined banks that have a distinct signature in the contour lines. Contour curvature is one of the important topographic attributes usually used for channel head identification; however, the curvature at channel heads may vary considerably between and even within watersheds. Therefore, uncertainty exists in the extracted channel heads due to the specified curvature threshold. In this paper, the locations of channel heads in 14 small mountainous watersheds are obtained using a nonparametric method based on the shape of contour lines generated from DEMs with a spatial resolution of 1 m, and the channel head curvature is computed from the extracted channel heads. The spatial distributions of the channel head curvature in these 14 watersheds have been analyzed, and another two watersheds with field-mapped channel heads are selected for validation. The results indicate that: (1) the channel head curvature is sensitive to the local terrain and varies within and between watersheds; (2) the Gamma distribution effectively fits the spatial distribution of the channel head curvature in all the selected watersheds; and (3) constant threshold-based methods for channel head identification gain significant location errors even within a single watershed.

scholarly journals Effect of Droplet Size and Counterions on the Spatial Distribution of Ions

2019 ◽  
Author(s):  
Victor Kwan ◽  
Styliani Consta
Keyword(s):  
Spatial Distribution ◽  
Reaction Mechanisms ◽  
Charge Carriers ◽  
Transfer Reactions ◽  
Spatial Distributions ◽  
Hydronium Ions ◽  
Ionic Atmosphere ◽  
Droplet Sizes ◽  
Charge Transfer Reactions ◽  
First Time

Electrosprayed droplets have emerged as a new environment for accelerating chemical reactions by orders of magnitude relative to their bulk analogues. Nevertheless the reaction mechanisms are still unknown. Unraveling the ion spatial distribution is critical as to where charge transfer reactions are likely to take place and as to their effect on the ionic atmosphere of macroions. Here we investigate the ion spatial distributions in aqueous droplets with diameters in the range of 5 nm to 16 nm with and without counterions using molecular dynamics. The charge carriers are Na, Cl ions and model hydronium ions. For the first time droplet sizes that are accessible to experimental scrutiny are modeled atomistically. <br>

An analysis of an arctic channel network using a digital elevation model

Geomorphology ◽  
1999 ◽  
Vol 29 (3-4) ◽  
pp. 339-353 ◽  
Author(s):  
James P McNamara ◽  
Douglas L Kane ◽  
Larry D Hinzman
Keyword(s):  
Digital Elevation Model ◽  
Channel Network ◽  
Digital Elevation ◽  
Elevation Model

Prioritization of Sub-Watersheds based on Morphometric parameters in Pare watershed, Arunachal Pradesh, India

2021 ◽  
pp. 53-64
Author(s):  
Waikhom Rahul Singh ◽  
Swapnali Barman ◽  
Nitesh Patidar
Keyword(s):  
Morphometric Parameters ◽  
Development Programs ◽  
Arunachal Pradesh ◽  
Watershed Development ◽  
Prioritization Process ◽  
Morphological Aspects ◽  
Management Measures ◽  
Digital Elevation ◽  
Mountainous Watersheds ◽  
Elevation Model

Mountainous watersheds are constantly under pressure of huge amount of soil loss due to soil erosion. Pare watershed is situated in the eastern Himalayan ranges of Arunachal Pradesh, India, which is subjected to such soil losses and its sub-watersheds are being degraded in many places. Watershed management programs are required in the area in which prioritization of sub-watersheds is one of the first steps. A study has been carried out to address this issue in the area to prioritize 26 sub-watersheds of Pare through morphometric analysis. The study used digital elevation model (DEM) to determine several morphometric parameters of the watershed. The analysis revealed that Pare river is of the 7th order comprising of 6127 stream segments running over the watersheds for about 2448 km. Based on the results obtained, the study area is an elongated well dissected watersheds with high relief and great presence of streams all over the watershed indicating faster runoff peak attainment which is synonymous to rapid transportation of sediment load. The analysis also revealed that SW25 required the top priority in dealing with soil, land and water management measures while least priority could be given to SW7 among all the sub-watersheds in the Pare basin. We suggest various stakeholders who are involved in watershed development programs in the region to take cues from the results obtained in this paper. The results of this study are quite satisfactory in understanding the various morphological aspects of the watershed. Nonetheless, efforts to improve the results can always be made through incorporation of land-use and soil information to enhance the prioritization process so that purpose utilization of the watershed may be reflected in the results.

scholarly journals Spatial Analysis Using Temporal Point Clouds in Advanced GIS: Methods for Ground Elevation Extraction in Slant Areas and Building Classifications

2019 ◽  
Vol 8 (3) ◽  
pp. 120 ◽  
Author(s):  
Sara Shirowzhan ◽  
Samad Sepasgozar
Keyword(s):  
Digital Elevation Model ◽  
Urban Growth ◽  
Urban Areas ◽  
Future Directions ◽  
3D Data ◽  
Contour Lines ◽  
Digital Elevation ◽  
The Future ◽  
Elevation Model ◽  
Skewness And Kurtosis

Deriving 3D urban development patterns is necessary for urban planners to control the future directions of 3D urban growth considering the availability of infrastructure or being prepared for fundamental infrastructure. Urban metrics have been used so far for quantification of landscape and land-use change. However, these studies focus on the horizontal development of urban form. Therefore, questions remain about 3D growth patterns. Both 3D data and appropriate 3D metrics are fundamentally required for vertical development pattern extraction. Airborne light detection and ranging (Lidar) as an advanced remote-sensing technology provides 3D data required for such studies. Processing of airborne lidar to extract buildings’ heights above a footprint is a major task and current automatic algorithms fail to extract such information on vast urban areas especially in hilly sites. This research focuses on proposing new methods of extraction of ground points in hilly urban areas using autocorrelation-based algorithms. The ground points then would be used for digital elevation model generation and elimination of ground elevation from classified buildings points elevation. Technical novelties in our experimentation lie in choosing a different window direction and also contour lines for the slant area, and applying moving windows and iterating non-ground extraction. The results are validated through calculation of skewness and kurtosis values. The results show that changing the shape of windows and their direction to be narrow long squares parallel to the ground contour lines, respectively, improves the results of classification in slant areas. Four parameters, namely window size, window shape, window direction and cell size are empirically chosen in order to improve initial digital elevation model (DEM) creation, enhancement of the initial DEM, classification of non-ground points and final creation of a normalised digital surface model (NDSM). The results of these enhanced algorithms are robust for generating reliable DEMs and separation of ground and non-ground points in slant urban scenes as evidenced by the results of skewness and kurtosis. Offering the possibility of monitoring urban growth over time with higher accuracy and more reliable information, this work could contribute in drawing the future directions of 3D urban growth for a smarter urban growth in the Smart Cities paradigm.

Spatial distribution of the intertidal snail Ilyanassa obsoleta in relation to parasitism by two species of trematodes

2000 ◽  
Vol 78 (7) ◽  
pp. 1137-1143 ◽  
Author(s):  
Dean G McCurdy ◽  
J Sherman Boates ◽  
Mark R Forbes
Keyword(s):  
Spatial Distribution ◽  
Intertidal Zone ◽  
Bay Of Fundy ◽  
Spatial Distributions ◽  
Ilyanassa Obsoleta ◽  
Intermediate Hosts ◽  
Corophium Volutator ◽  
Vertical Distributions ◽  
Second Intermediate Host ◽  
Intertidal Snail

We studied the spatial distributions of mud snails (Ilyanassa obsoleta) infected by two trematodes, Lepocreadium setiferoides and Gynaecotyla adunca, on a macrotidal mudflat in the Minas Basin, Bay of Fundy. Snails, as first intermediate hosts, were castrated by both parasites, and we found no evidence of sex differences in parasitism. Similar to previous work, prevalence of L. setiferoides in I. obsoleta increased exponentially with host size (and age). Unexpectedly, prevalence of G. adunca decreased over the largest size classes of snails, a result that may be due to several causes. Distributions of both parasites across the intertidal zone differed from previous accounts in that snails infected with L. setiferoides were found only in the middle of the intertidal zone, whereas prevalence of G. adunca increased exponentially moving seaward. Several species of polychaetes could be infected by L. setiferoides in the laboratory and may act as appropriate second intermediate hosts, whereas only the amphipod Corophium volutator served as a second intermediate host for G. adunca. Finally, the vertical distributions of I. obsoleta infected by either species of trematode overlap with distributions of apparent or known second intermediate hosts.

scholarly journals An objective approach for feature extraction: distribution analysis and statistical descriptors for scale choice and channel network identification

2011 ◽  
Vol 15 (5) ◽  
pp. 1387-1402 ◽  
Author(s):  
G. Sofia ◽  
P. Tarolli ◽  
F. Cazorzi ◽  
G. Dalla Fontana
Keyword(s):  
Window Size ◽  
Distribution Analysis ◽  
Step Method ◽  
Channel Network ◽  
Standard Score ◽  
Accurate Localization ◽  
Subjective Threshold ◽  
Topographic Attributes ◽  
Score Normalization ◽  
Network Identification

Abstract. A statistical approach to LiDAR derived topographic attributes for the automatic extraction of channel network and for the choice of the scale to apply for parameter evaluation is presented in this paper. The basis of this approach is to use distribution analysis and statistical descriptors to identify channels where terrain geometry denotes significant convergences. Two case study areas with different morphology and degree of organization are used with their 1 m LiDAR Digital Terrain Models (DTMs). Topographic attribute maps (curvature and openness) for various window sizes are derived from the DTMs in order to detect surface convergences. A statistical analysis on value distributions considering each window size is carried out for the choice of the optimum kernel. We propose a three-step method to extract the network based (a) on the normalization and overlapping of openness and minimum curvature to highlight the more likely surface convergences, (b) a weighting of the upslope area according to these normalized maps to identify drainage flow paths and flow accumulation consistent with terrain geometry, (c) the standard score normalization of the weighted upslope area and the use of standard score values as non subjective threshold for channel network identification. As a final step for optimal definition and representation of the whole network, a noise-filtering and connection procedure is applied. The advantage of the proposed methodology, and the efficiency and accurate localization of extracted features are demonstrated using LiDAR data of two different areas and comparing both extractions with field surveyed networks.

scholarly journals Spatial Distributions, Characteristics, and Applications of Craniofacial Stem Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Geru Zhang ◽  
Qiwen Li ◽  
Quan Yuan ◽  
Shiwen Zhang
Keyword(s):  
Stem Cells ◽  
Spatial Distribution ◽  
Stem Cell ◽  
Cranial Sutures ◽  
Stem Cell Markers ◽  
Spatial Distributions ◽  
Self Renewal ◽  
Stem Cell Niches ◽  
Multidirectional Differentiation

Stem cells play an irreplaceable role in the development, homeostasis, and regeneration of the craniofacial bone. Multiple populations of tissue-resident craniofacial skeletal stem cells have been identified in different stem cell niches, including the cranial periosteum, jawbone marrow, temporomandibular joint, cranial sutures, and periodontium. These cells exhibit self-renewal and multidirectional differentiation abilities. Here, we summarized the properties of craniofacial skeletal stem cells, based on their spatial distribution. Specifically, we focused on the in vivo genetic fate mapping of stem cells, by exploring specific stem cell markers and observing their lineage commitment in both the homeostatic and regenerative states. Finally, we discussed their application in regenerative medicine.

scholarly journals Evaluation of Reliable Digital Elevation Model Resolution for TOPMODEL in Two Mountainous Watersheds, South Korea

2019 ◽  
Vol 9 (18) ◽  
pp. 3690 ◽  
Author(s):  
Daeryong Park ◽  
Huan-Jung Fan ◽  
Jun-Jie Zhu ◽  
Sang-Eun Oh ◽  
Myoung-Jin Um ◽  
...  
Keyword(s):  
South Korea ◽  
Cell Size ◽  
Digital Elevation Model ◽  
River Basin ◽  
Grid Cell ◽  
Dem Resolution ◽  
Digital Elevation ◽  
Mountainous Watersheds ◽  
Elevation Model ◽  
Digital Elevation Model Resolution

This study analyzed the result of parameter optimization using the digital elevation model (DEM) resolution in the TOPography-based hydrological MODEL (TOPMODEL). Also, this study investigated the sensitivity of the TOPMODEL efficiency by applying the varying resolution of the DEM grid cell size. This work applied TOPMODEL to two mountainous watersheds in South Korea: the Dongkok watershed in the Wicheon river basin and the Ieemokjung watershed in the Pyeongchang river basin. The DEM grid cell sizes were 5, 10, 20, 40, 80, 160, and 300 m. The effect of DEM grid cell size on the runoff was investigated by using the DEM grid cell size resolution to optimize the parameter sets. As the DEM grid cell size increased, the estimated peak discharge was found to increase based on different parameter sets. In addition, this study investigated the DEM grid cell size that was most reliable for use in runoff simulations with various parameter sets in the experimental watersheds. The results demonstrated that the TOPMODEL efficiencies in both the Dongkok and Ieemokjung watersheds rarely changed up to a DEM grid-size resolution of about 40 m, but the TOPMODEL efficiencies changed with the coarse resolution as the parameter sets were changed. This study is important for understanding and quantifying the modeling behaviors of TOPMODEL under the influence of DEM resolution based on different parameter sets.

AUTOMATIC CONTOURING USING BICUBIC FUNCTIONS

Geophysics ◽  
1972 ◽  
Vol 37 (4) ◽  
pp. 669-674 ◽  
Author(s):  
R. C. Hessing ◽  
Henry K. Lee ◽  
Alan Pierce ◽  
Eldon N. Powers
Keyword(s):  
Spatial Distribution ◽  
Cross Sections ◽  
Digital Computer ◽  
Smooth Surface ◽  
Contour Line ◽  
Contour Maps ◽  
Volume Calculations ◽  
Contour Lines ◽  
Data Points ◽  
Automatic Contouring

A method is described for using a digital computer to construct contour maps automatically. Contour lines produced by this method have correct relations to given discrete data points regardless of the spatial distribution of these points. The computer‐generated maps are comparable to those drawn manually. The region to be contoured is divided into quadrilaterals whose vertices include the data points. After supplying values at each of the remaining vertices by using a surface‐fitting technique, bicubic functions are constructed on each quadrilateral to form a smooth surface through the data points. Points on a contour line are obtained from these surfaces by solving the resulting cubic equations. The bicubic functions may be used for other calculations consistent with the contour maps, such as interpolation of equally spaced values, calculation of cross‐sections, and volume calculations.

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