Smoothing of Digital Elevation Models and the Alteration of Overland Flow Path Length Distributions

2021 ◽  
Author(s):  
Nigel Van Nieuwenhuizen ◽  
John B. Lindsay ◽  
Ben DeVries
Keyword(s):  
Path Length ◽  
Overland Flow ◽  
Digital Elevation Models ◽  
Flow Path ◽  
Digital Elevation ◽  
Flow Path Length

scholarly journals Enhanced DEM-based flow path delineation methods for urban flood modelling

2012 ◽  
Vol 15 (2) ◽  
pp. 568-579
Author(s):  
J. P. Leitão ◽  
D. Prodanović ◽  
S. Boonya-aroonnet ◽  
Č. Maksimović
Keyword(s):  
Urban Areas ◽  
Overland Flow ◽  
Flow Path ◽  
Flow Paths ◽  
Urban Flood ◽  
Bouncing Ball ◽  
Digital Elevation ◽  
Synthetic Test ◽  
Water Accumulation ◽  
Flooding Events

In order to simulate surface runoff and flooding, one-dimensional (1D) overland flow networks can be automatically delineated using digital elevation models (DEM). The resulting network comprises flow paths and terrain depressions/ponds and is essential to reliably model pluvial (surface) flooding events in urban areas by so-called 1D/1D models. Conventional automatic DEM-based flow path delineation methods have problems in producing realistic overland flow paths when detailed high-resolution DEMs of urban areas are used. The aim of this paper is to present the results of research and development of three enhanced DEM-based overland flow path delineation methods; these methods are triggered when the conventional flow path delineation process stops due to a flow obstacle. Two of the methods, the ‘bouncing ball and buildings’ and ‘bouncing ball and A*’ methods, are based on the conventional ‘bouncing ball’ concept; the third proposed method, the ‘sliding ball’ method, is based on the physical water accumulation concept. These enhanced methods were tested and their results were compared with results obtained using two conventional flow path delineation methods using a semi-synthetic test DEM. The results showed significant improvements in terms of the reliability of the delineated overland flow paths when using these enhanced methods.

Improvements to the Performance of a Prototype Pulse, Pressure-Gain, Gas Turbine Combustor

1990 ◽  
Vol 112 (1) ◽  
pp. 67-72 ◽  
Author(s):  
J. A. C. Kentfield ◽  
L. C. V. Fernandes
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Pulse Pressure ◽  
Path Length ◽  
Flow Path ◽  
Maximum Pressure ◽  
Gas Turbine Combustor ◽  
Flow Passage ◽  
Delivery Pressure ◽  
Flow Path Length

A description is given of a simple, prototype, pulse, pressure-gain combustor for a gas turbine. The work reported was targeted at alleviating problems previously observed with the prototype combustor. These were related to irreversibilities, causing a performance deficiency, in the secondary flow passage. The work consisted of investigating experimentally the effect of tuning the secondary-flow path length, adding a flow restrictor at the combining-cone entry station, and redesigning the combining cone itself. The overall result was to eradicate the previously noted performance deficiency, thereby increasing the maximum pressure gain obtained in the gas turbine from 1.6 to 4.0 percent of the compressor absolute delivery pressure.

Research on Longitudinal Slope of Highway Based on Control by Flow Path Length

2012 ◽  
Vol 178-181 ◽  
pp. 1672-1675
Author(s):  
Zhuo Zhang ◽  
Jian Ping Gao
Keyword(s):  
Linear Regression ◽  
Path Length ◽  
Flow Path ◽  
Regression Method ◽  
Linear Regression Method ◽  
Mechanical Theory ◽  
Multiple Linear Regression Method ◽  
Straight Line ◽  
Longitudinal Slope ◽  
Flow Path Length

Flow path on the highway is longer, driving exits the more dangerous. Based on the mechanical theory, the calculation models of the flow path length in different sections were built by FDM and multiple linear regression method. The flow path length of different section and different longitudinal slope was studied. The results show that: in addition to straight line and circle curve, when the number of lane is more than 4 and longitudinal slope is greater than 4%, the flow path length at other sections almost exceeded the prescribed value. Made the flow path length as control index, the amendment value on the maximum longitudinal slope of highway is proposed.

scholarly journals Improvements to the Performance of a Prototype Pulse, Pressure Gain, Gas-Turbine Combustor

1989 ◽  
Author(s):  
J. A. C. Kentfield ◽  
L. C. V. Fernandes
Keyword(s):  
Secondary Flow ◽  
Gas Turbine ◽  
Pulse Pressure ◽  
Path Length ◽  
Flow Path ◽  
Maximum Pressure ◽  
Gas Turbine Combustor ◽  
Flow Passage ◽  
Delivery Pressure ◽  
Flow Path Length

A description is given of a simple, prototype, pulse, pressure-gain, combustor for a gas turbine. The work reported was targeted at alleviating problems previously observed with the prototype combustor. These were related to irreversibilities, causing a performance deficiency, in the secondary flow passage. The work consisted of investigating experimentally the effect of tuning the secondary-flow path-length, adding a flow restrictor at the combining-cone entry station and redesigning the combining-cone itself. The overall result was to eradicate the previously noted performance deficiency thereby increasing the maximum pressure-gain obtained in the gas turbine from 1.6% to 4.0% of the compressor absolute delivery pressure.

scholarly journals A versatile, linear complexity algorithm for flow routing in topographies with depressions

2019 ◽  
Vol 7 (2) ◽  
pp. 549-562 ◽  
Author(s):  
Guillaume Cordonnier ◽  
Benoît Bovy ◽  
Jean Braun
Keyword(s):  
Linear Time ◽  
Digital Elevation Models ◽  
Flow Path ◽  
Sequential Algorithm ◽  
Drainage Basins ◽  
Flow Routing ◽  
Flow Paths ◽  
Generic Structure ◽  
Digital Elevation ◽  
The Common

Abstract. We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. In addition to its efficiency, our proposed method also has the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well, such as the simulation of erosion. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study.

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.

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