scholarly journals A Combined Field and Numerical Modeling Study to Assess the Longitudinal Channel Slope Evolution in a Mixed Alluvial and Soft Bedrock Stream

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 735 ◽  
Author(s):  
Wu ◽  
Yeh ◽  
Lai
Keyword(s):  
Numerical Modeling ◽  
Cross Sections ◽  
Large Scale ◽  
Spatial Scales ◽  
Scale Analysis ◽  
Entire Study ◽  
Study Approach ◽  
Study Results ◽  
Channel Slope ◽  
Longitudinal Channel

A study approach is developed to assess the longitudinal channel slope under the equilibrium condition as well as the transient evolution of a mixed alluvial-soft-bedrock stream. Both the historical field data and 2D mobile-bed numerical modeling are adopted. The proposed approach is applied to a 14 km reach downstream of the Ji-Ji Weir, Chuo-Shui River, Taiwan, where continuous maintenance works have been carried out to stabilize this reach. In this study, the temporal evolution of the longitudinal channel profile is assessed numerically with three spatial scales: The large (the entire study reach), the medium (four sub-reaches), and the local (cross-sections) scale. The large scale analysis is the approach for purely alluvial streams and is shown to be difficult to use to characterize mixed alluvial-bedrock streams. The local scale analysis shows that the soft-bedrock incision has a widely fluctuating slope, reflecting the compound environmental forcing and complex riverbed setting. With the medium scale analysis, the longitudinal channel profile is found to follow a predictive trend if the reach is partitioned into four distinctive sub-reaches. Characteristics of the dynamic channel slope evolution in different spatial scales are computed and presented. The study results can be used to select the proper locations and types of the engineering stabilizing structures in a mixed alluvial and soft bedrock stream

scholarly journals Flood Risk Assessment and Quantification at the Community and Property Level in the State of Iowa

2021 ◽  
Author(s):  
Enes Yildirim ◽  
Ibrahim Demir
Keyword(s):  
Risk Assessment ◽  
High Resolution ◽  
Flood Risk ◽  
Large Scale ◽  
Spatial Scales ◽  
The United States ◽  
Flood Risk Assessment ◽  
Study Region ◽  
Study Results ◽  
Flood Maps

Flood risk assessment contributes to identifying at-risk communities and supports mitigation decisions to maximize benefits from the investments. Large-scale risk assessments generate invaluable inputs for prioritizing regions for the distribution of limited resources. High-resolution flood maps and accurate parcel information are critical for flood risk analysis to generate reliable outcomes for planning, preparedness, and decision-making applications. Large-scale damage assessment studies in the United States often utilize the National Structure Inventory (NSI) or HAZUS default dataset, which results in inaccurate risk estimates due to the low geospatial accuracy of these datasets. On the other hand, some studies utilize higher resolution datasets, however they are limited to focus on small scales, for example, a city or a Hydrological United Code (HUC)-12 watershed. In this study, we collected extensive detailed flood maps and parcel datasets for many communities in Iowa to carry out a large-scale flood risk assessment. High-resolution flood maps and the most recent parcel information are collected to ensure the accuracy of risk products. The results indicate that the Eastern Iowa communities are prone to a higher risk of direct flood losses. Our model estimates nearly $10 million in average annualized losses, particularly in large communities in the study region. The study highlights that existing risk products based on FEMA's flood risk output underestimate the flood loss, specifically in highly populated urban communities such as Bettendorf, Cedar Falls, Davenport, Dubuque, and Waterloo. Additionally, we propose a flood risk score methodology for two spatial scales (e.g., HUC-12 watershed, property) to prioritize regions and properties for mitigation purposes. Lastly, the watershed-scale study results are shared through a web-based platform to inform the decision-makers and the public.

scholarly journals KEBIJAKAN PEMERINTAH DALAM PENANGANAN PANDEMI COVID-19

2020 ◽  
Vol 3 (2) ◽  
pp. 267
Author(s):  
Darmin Tuwu
Keyword(s):  
Large Scale ◽  
Social Protection ◽  
Government Policies ◽  
Personal Hygiene ◽  
Study Approach ◽  
Social Welfare Services ◽  
The Social ◽  
Study Results ◽  
The Government ◽  
At Home

This paper aims to elaborate on how government policies prevent and deal with COVID-19. The method used is a qualitative method with a case study approach. The focus of the study is government policies and events that follow the implementation of the policy period from March to June 2020 related to government policies in the prevention and treatment of COVID-19. The study results show that government policies to prevent the spread of Coronavirus transmission such as the policy of staying at home; Social distancing; Physical Restrictions; Use of Personal Protective Equipment; Maintain Personal Hygiene; Work and Study at home; Postpone all activities that gather a lot of people; Large-scale social restrictions; until the implementation of the New Normal policy. In addition, the government has also implemented social assistance and social protection policies to ensure that the community can survive, not only the Social Welfare Services Government group but also the high-class community.

Mangroves as Fish Habitat

2015 ◽  
Keyword(s):  
Numerical Modeling ◽  
Quantitative Data ◽  
Large Scale ◽  
Scientific Literature ◽  
Spatial Scales ◽  
Fish Habitat ◽  
Systematic Search ◽  
Small Scale ◽  
Data Set ◽  
Subsistence Fishing

<em>Abstract</em>.—Mangroves are widely understood to be important habitats for fisheries, supporting resident fish, crustacean, and mollusk populations as well as acting as nursery grounds for species that are targeted by offshore fisheries. There is, however, a lack of quantitative data on fisheries that operate in and around mangroves. We carried out a systematic search to gather data on mangrove fisheries from the scientific literature. We filtered the 4,358 studies returned by the search based on their title and abstract and extracted data from 169 of these. Despite the abundance of literature on mangrove fisheries, we were unable to build a data set of comparable, quantitative data of sufficient size to support numerical modeling approaches. In part, this is due to the variety of mangrove fisheries, which range from small-scale subsistence fishing for mollusks and crabs to large-scale industrialized prawn trawling. This is compounded by the broad range of reporting methods and metrics encountered in the literature. We make a number of recommendations to guide the future reporting of mangrove fisheries to allow for better quantification and comparison of fisheries values at large spatial scales.

Characteristic Spatial Scales of Particle Clusters Formed in Gas-Solid Flow

2007 ◽  
Author(s):  
T. Tsuji ◽  
A. Ito ◽  
T. Tanaka
Keyword(s):  
Spatial Scale ◽  
Large Scale ◽  
Deterministic Model ◽  
Spatial Scales ◽  
Direct Simulation Monte Carlo ◽  
Domain Size ◽  
Three Dimensions ◽  
Wave Number ◽  
Particle Collision ◽  
Study Results

Spatial scale characteristics of particle clusters are investigated by directly performing Fourier transform of spatial particle concentration distributions. Flow field data are obtained by large-scale Eulerian / Lagrangian simulations. All calculations are performed in three-dimensions and more than sixteen million particles are tracked in the maximum case. The inter-particle collision plays an important role for the development of particle clusters. In this study, results obtained by using the stochastic model based on direct simulation Monte Carlo (DSMC) are compared with that by the deterministic model. The results obtained by DSMC method agree quantitatively with deterministic model. Particle clusters consist of multiple-spatial scale components and the low wave-number, hence large-scale structure, is dominant. Dependency on the domain size and resolution is also investigated in detail.

scholarly journals On Drawing Conclusions Nine Years After the Exxon Valdez Oil Spill

The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 886-892 ◽  
Author(s):  
John A. Wiens ◽  
Robert H. Day ◽  
Stephen M. Murphy ◽  
Keith R. Parker
Keyword(s):  
Oil Spill ◽  
Large Scale ◽  
Spatial Scales ◽  
Prince William Sound ◽  
Exxon Valdez ◽  
Causal Explanations ◽  
Exxon Valdez Oil Spill ◽  
Environmental Perturbations ◽  
Study Results ◽  
The Status

Abstract We comment on the paper of Irons et al. (2000), which evaluated the status of several marine bird taxa in Prince William Sound, Alaska, nine years after the Exxon Valdez oil spill. We discuss concerns about the effects on the study design of inherent differences between the oiled and unoiled areas; about interpretations of results that use inconsistent criteria to define the spatial scales of analysis; and about explanations of underlying causes that are not empirically founded. These comments highlight general difficulties in assessing the effects of large-scale environmental perturbations. It is important to draw conclusions about the effects of such events, but the conclusions must be founded on accuracy in reporting study results, caution in interpreting the results, and adequate consideration of alternative causal explanations for the observed results. Acerca de Inferir Conclusiones Nueve Años después del Derrame de Petróleo del Exxon Valdez Resumen. Comentamos el artículo de Irons et al. (2000), que evaluó el estado de varios taxa de aves marinas en Prince William Sound, Alaska, nueve años después del derrame de petróleo del Exxon Valdez. Discutimos inquietudes acerca de los efectos del diseño del estudio en relación a diferencias inherentes entre las áreas afectadas y no afectadas por el petróleo; sobre las interpretaciones de los resultados que usan criterios incosistentes para definir las escalas espaciales del análisis; y sobre explicaciones de causas subyacentes que no están empíricamente fundamentadas. Estos comentarios resaltan las dificultades generales en establecer los efectos de grandes perturbaciones ambientales. Es importante inferir conclusiones sobre los efectos de dichos eventos, pero estas conclusiones deben considerar la presición de los resultados presentados, ser precavidas al interpretar los resultados, y considerar adecuadamente explicaciones causales alternativas para los resultados observados.

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