scholarly journals Assessing the impact of different sources of topographic data on 1-D hydraulic modelling of floods

2014 ◽  
Vol 11 (7) ◽  
pp. 7375-7408 ◽  
Author(s):  
A. Md Ali ◽  
D. P. Solomatine ◽  
G. Di Baldassarre
Keyword(s):  
Thermal Emission ◽  
Low Cost ◽  
Water Levels ◽  
Flood Inundation ◽  
Model Accuracy ◽  
Hydraulic Models ◽  
Topographic Data ◽  
Ground Survey ◽  
The Impact ◽  
Different Sources

Abstract. Topographic data, such as digital elevation models (DEMs), are essential input in flood inundation modelling. DEMs can be derived from several sources either through remote sensing techniques (space-borne or air-borne imagery) or from traditional methods (ground survey). The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), the Light Detection and Ranging (LiDAR), and topographic contour maps are some of the most commonly used sources of data for DEMs. These DEMs are characterized by different precision and accuracy. On the one hand, the spatial resolution of low-cost DEMs from satellite imagery, such as ASTER and SRTM, is rather coarse (around 30–90 m). On the other hand, LiDAR technique is able to produce a high resolution DEMs (around 1m), but at a much higher cost. Lastly, contour mapping based on ground survey is time consuming, particularly for higher scales, and may not be possible for some remote areas. The use of these different sources of DEM obviously affects the results of flood inundation models. This paper shows and compares a number of hydraulic models developed using HEC-RAS as model code and the aforementioned sources of DEM as geometric input. The study was carried out on a reach of the Johor River, in Malaysia. The effect of the different sources of DEMs (and different resolutions) was investigated by considering the performance of the hydraulic models in simulating flood water levels as well as inundation maps. The outcomes of our study show that the use of different DEMs has serious implications to the results of hydraulic models. The outcomes also indicates the loss of model accuracy due to re-sampling the highest resolution DEM (i.e. LiDAR 1 m) to lower resolution are much less compared to the loss of model accuracy due to the use of low-cost DEM that have not only a lower resolution, but also a lower quality. Lastly, to better explore the sensitivity of the hydraulic models to different DEMs, we performed an uncertainty analysis based on the GLUE methodology.

scholarly journals Assessing the impact of different sources of topographic data on 1-D hydraulic modelling of floods

2015 ◽  
Vol 19 (1) ◽  
pp. 631-643 ◽  
Author(s):  
A. Md Ali ◽  
D. P. Solomatine ◽  
G. Di Baldassarre
Keyword(s):  
Low Cost ◽  
Water Levels ◽  
Test Model ◽  
Flood Inundation ◽  
Model Accuracy ◽  
Flood Water ◽  
Hydraulic Models ◽  
Topographic Data ◽  
Ground Survey ◽  
Different Sources

Abstract. Topographic data, such as digital elevation models (DEMs), are essential input in flood inundation modelling. DEMs can be derived from several sources either through remote sensing techniques (spaceborne or airborne imagery) or from traditional methods (ground survey). The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), the light detection and ranging (lidar), and topographic contour maps are some of the most commonly used sources of data for DEMs. These DEMs are characterized by different precision and accuracy. On the one hand, the spatial resolution of low-cost DEMs from satellite imagery, such as ASTER and SRTM, is rather coarse (around 30 to 90 m). On the other hand, the lidar technique is able to produce high-resolution DEMs (at around 1 m), but at a much higher cost. Lastly, contour mapping based on ground survey is time consuming, particularly for higher scales, and may not be possible for some remote areas. The use of these different sources of DEM obviously affects the results of flood inundation models. This paper shows and compares a number of 1-D hydraulic models developed using HEC-RAS as model code and the aforementioned sources of DEM as geometric input. To test model selection, the outcomes of the 1-D models were also compared, in terms of flood water levels, to the results of 2-D models (LISFLOOD-FP). The study was carried out on a reach of the Johor River, in Malaysia. The effect of the different sources of DEMs (and different resolutions) was investigated by considering the performance of the hydraulic models in simulating flood water levels as well as inundation maps. The outcomes of our study show that the use of different DEMs has serious implications to the results of hydraulic models. The outcomes also indicate that the loss of model accuracy due to re-sampling the highest resolution DEM (i.e. lidar 1 m) to lower resolution is much less than the loss of model accuracy due to the use of low-cost DEM that have not only a lower resolution, but also a lower quality. Lastly, to better explore the sensitivity of the 1-D hydraulic models to different DEMs, we performed an uncertainty analysis based on the GLUE methodology.

scholarly journals STUDI PEMETAAN DAERAH GENANGAN BANJIR DAS SEI KAMBING DENGAN SISTEM INFORMASI GEOGRAFIS

Teras Jurnal ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 165
Author(s):  
Asril Zevri
Keyword(s):  
River Basin ◽  
Return Period ◽  
Daily Rainfall ◽  
Water Levels ◽  
Disaster Mitigation ◽  
Flood Inundation ◽  
The Public ◽  
Inundation Area ◽  
Flood Level ◽  
The Impact

<p><em>Sei Sikambing River Basin is one of the Sub Das of Deli River which has an important role in water requirement in Medan City. Rainfall with high intensity is supported by changes in land use causing floods which reach 0.6 m to 1 m from river banks. The purpose of this study was to map the Sei Kambing River basin flood inundation area as information to the public in disaster mitigation efforts. The scope of this research is to analyze the maximum daily rainfall with a return period of 2 to 100 years, analyze flood discharge with a return period of 2 to 100, analyze flood water levels with HECRAS software, and spatially map flood inundation areas with GIS. The results showed that the return flood rate of the Sikambing watershed with a 25-year return period of 211.94 m<sup>3</sup>/s caused the flood level of the Sikambing watershed to be between 1.7 m to 3.7 m. The Sikambing watershed flood inundation area reached an area of 1.19 Km<sup>2</sup> which resulted in the impact of flooding on 5 sub-districts in Medan, namely Medan Selayang District, Medan Sunggal, Medan Petisah, Medan Helvetia, and West Medan.</em><em></em></p>

scholarly journals A Review on the Methods of Industrial Waste Water Treatment

2021 ◽  
pp. 20-31
Author(s):  
Khandakar M. Nahiun ◽  
Bijoyee Sarker ◽  
Kamrun N. Keya ◽  
Fatin I. Mahir ◽  
Shahirin Shahida ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Low Cost ◽  
Waste Water Treatment ◽  
Industrial Wastes ◽  
Public Concern ◽  
Industrial Waste Water ◽  
Halogenated Hydrocarbon ◽  
Aerobic Wastewater Treatment ◽  
The Impact ◽  
Different Sources

Nowadays environmental pollution is a great threat to us. Water resources are mostly polluted by industrial wastes. Among all other pollutions, water pollution is one of the most vital pollution caused by different sources like industrial, domestic, sewage, hazardous waste, municipal waste, medical waste, manufacturing waste, etc. Public concern over the impact of wastewater has increased. There are several methods for the treatment of wastewater. Among them, techniques like coagulation, adsorption, activated sludge are prominent. The use of aerobic wastewater treatment as a reductive medium is receiving attention for its low cost of operation and low cost of maintenance. The uses of low-cost adsorbents are also effective in wastewater treatment. The aerobic wastewater is effective in degrading the contaminants. There are different electrolytic techniques as well for wastewater treatment. This paper reviews the possible techniques available for the treatment of wastewater to remove contaminants such as halogenated hydrocarbon compounds, heavy metals, dyes, pigments etc. from the wastewater.

scholarly journals Jamming/Garbling assessment and possible mitigations in the OpenSky network

10.29007/fn6z ◽  
2019 ◽  
Author(s):  
Mauro Leonardi ◽  
Martin Strohmeier ◽  
Vincent Lenders
Keyword(s):  
Radio Frequency ◽  
Real World ◽  
Traffic Control ◽  
Surveillance System ◽  
Air Traffic Control ◽  
Low Cost ◽  
Frequency Channel ◽  
Mitigation Techniques ◽  
The Impact ◽  
Different Sources

The Automatic Dependent Surveillance-Broadcast (ADS-B) technology is one of the pillars of the future surveillance system for air traffic control. However, its many fundamental vulnerabilities are well known and an active area of research. This paper examines two closely related ADS-B radio frequency channel issues, jamming and garbling.Both jamming and garbling produce the same physical effect: the reception of mixed signals, coming from different sources (usually not co-located). In this paper, we assess the impact of these reception problems and examine three separate mitigation techniques. Through the use of theoretical evaluations, simulations and real-world analysis based on data collected by the OpenSky Network, we compare their effectiveness and establish a first baseline for their use in modern low-cost, crowdsourced ADS-B networks.

Flood Inundation Analysis and Mitigation with a Coupled 1D-2D Hydraulic Model: A Case Study in Kochi, Japan

2015 ◽  
Vol 10 (6) ◽  
pp. 1099-1109 ◽  
Author(s):  
M. A. C. Niroshinie ◽  
◽  
Yasuo Nihei ◽  
Kazuaki Ohtsuki ◽  
Shoji Okada ◽  
...  
Keyword(s):  
Flood Plain ◽  
Water Levels ◽  
Flood Inundation ◽  
Two Dimensional ◽  
Hydraulic Models ◽  
Mountain Watershed ◽  
Maximum Water ◽  
Kochi Prefecture ◽  
Inundation Model

Coupled one and two-dimensional (1D-2D) hydraulic models play a significant role in analyzing flooding problems to find possible solutions as they can reproduce the actual situations relatively accurately. This paper summarizes approaches to flood inundation analysis and mitigation with coupled 1D-2D hydraulic models of a small mountain watershed in Japan. A detailed flood inundation model including the effects of drainages, pumping, inflow from mountain sub-watersheds and flood gates is developed using coupled 1D-2D hydraulic models. The model is applied to the inundation in Kubokawa, a small town in Kochi Prefecture, Japan on August 9-10, 2014. Simulated and observed maximum water levels along the river and maximum inundations in the flood plain are compared and found to be consistent. Causes of the flooding and percentage of contribution are quantitatively identified, and countermeasures to reduce the effects of flooding are proposed.

Optimizing SAR-based Flood Extent Assimilation for Improved Flood Inundation Forecasts

2020 ◽  
Author(s):  
Antara Dasgupta ◽  
Renaud Hostache ◽  
Raaj Ramsankaran ◽  
Guy Schumann ◽  
Stefania Grimaldi ◽  
...  
Keyword(s):  
Water Levels ◽  
Flow Behaviour ◽  
Expected Improvement ◽  
Loop Model ◽  
Flood Inundation ◽  
Flood Wave ◽  
Hydraulic Modelling ◽  
Operational Forecasting ◽  
Sar Imagery ◽  
The Impact

&lt;p&gt;Floods can have extremely expensive and often fatal consequences, thereby necessitating accurate flood inundation forecasts for increased preparedness and resilience. In an operational forecasting scenario, inflow uncertainties propagated from precipitation forecasts dominate and lead to inherently erroneous predictions of flood inundation, frequently impeding their application to rescue and response operations. Thus, it is expected that assimilating independent inundation observations, from Synthetic Aperture Radar (SAR) sensors for example, may reduce the inherent uncertainty in hydraulic modelling. The increasing number of SAR satellites, with their all-weather/all-day imaging capabilities, have increased the probability of monitoring flood dynamics from space. SAR-based flood extents were previously used to indirectly retrieve floodplain water levels in conjunction with digital elevation models. However, studies highlighted this process as an additional source of uncertainty, leading to the development of algorithms for the direct assimilation of flood extent into hydraulic flood inundation forecasting chains. The efficiency of flood extent assimilation is keenly sensitive to the spatiotemporal observation characteristics, and so the expected improvement in the forecast strongly depends on the acquisition timing with respect to the position of the flood wave. In this study, numerical experiments were used to simulate multiple spatiotemporal SAR acquisition scenarios, to identify the optimum measurement design for targeted satellite acquisition, to best facilitate flood extent assimilation. A particle filter based flood extent assimilation framework was developed using the hydraulic model LISFLOOD-FP, and implemented for the 2011 flood event in the Clarence Catchment, Australia. An operational forecasting scenario was emulated for the open loop model ensemble, with the consideration of temporally correlated, variance changing uncertainties in inflows, simulating hydrological model forecasts. The impact of assimilating flood extent at reaches exhibiting uniform flow behaviour, with different combinations of first visit and revisit intervals were investigated. Results indicate that the optimum timing and frequency of targeted SAR acquisitions differs with respect to reach hydraulic characteristics and that images acquired after the peak is observed in the channel are most informative for the forecast. Note that the maximum inundation extent in the floodplain always follows the channel peak, and therefore, post-peak images with respect to the within reach flood wave could improve predictions during the peak in the floodplain. Moreover, a single image assimilated at a reaches exhibiting more diffusive flow behaviour just after the peak, could result in improvements comparable to the assimilation of multiple images elsewhere. Findings from the study will allow the optimal utilization of SAR imagery to overcome localized model uncertainties, and help to maximize the accuracy of inundation forecasts.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;ul&gt;&lt;li&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;Flood inundation modelling, flood extent assimilation, SAR, data assimilation, hydraulic modelling, forecast uncertainty&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

Advancing dairy farming profitability through research

2001 ◽  
pp. 17-22
Author(s):  
J.R. Caradus ◽  
D.A. Clark
Keyword(s):  
Research And Development ◽  
Dairy Cow ◽  
Low Cost ◽  
Pasture Management ◽  
Nitrogen Fertiliser ◽  
Grass Endophyte ◽  
Forage Species ◽  
Development Outcomes ◽  
Dairy Cow Nutrition ◽  
The Impact

The New Zealand dairy industry recognises that to remain competitive it must continue to invest in research and development. Outcomes from research have ensured year-round provision of low-cost feed from pasture while improving productivity. Some of these advances, discussed in this paper, include the use of white clover in pasture, understanding the impacts of grass endophyte, improved dairy cow nutrition, the use of alternative forage species and nitrogen fertiliser to improve productivity, demonstration of the impact of days-in-milk on profitability, and the use of feed budgeting and appropriate pasture management. Keywords: dairy, profitability, research and development

Role of chromium (III) in the nutrition of pigs and cattle

2016 ◽  
Vol 3 (2) ◽  
pp. 56-62
Author(s):  
R. Iskra ◽  
V. Vlizlo ◽  
R. Fedoruk
Keyword(s):  
Growth And Development ◽  
Reproductive Function ◽  
Metabolic Effect ◽  
Considerable Part ◽  
Cultural Medium ◽  
Milk Performance ◽  
Chromium Compounds ◽  
The Impact ◽  
Different Sources

The results of our studies and the data of modern literature regarding the biological role of Cr(III) compounds in conditions of their application in the nutrition for pigs and cattle are discussed. The metabolic impact of Cr(III), coming from different sources – mineral and organic compounds, obtained by chemical synthesis or a nanotechnological method (chromium citrate), as well as in the form of biocomplexes from the cultural medium of Saccharomyces cerevisiae yeasts was analyzed. The metabolic connection between the impact of Cr(III) and the biosynthesis of some hormones – insulin, cortisol – as well as the sensitivity of some tissues and organs to the effect of chromium compounds was studied. A considerable part of the review material was dedicated to the metabolic effect of Cr(III) compounds on the reproductive function of pigs and cattle and their impact on the viability of the offspring and gametes of animals. The data about the stimulating effect of Cr(III) on the growth and development of the organism of piglets and calves, meat and milk performance of these species of animals are discussed. The relevance of dosing Cr(III) in the nutrition of pigs and cattle is highlighted.

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