Assessment of flood mitigation through riparian detention in response to a changing climate – a case study     

Kwan Tun Lee  Pin-Chun Huang 《Journal of Earth System Science》2018,127(6):83

Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to a changing climate in the Tou-Chien River basin of Taiwan. An integrated 1D–2D flow model was used to simulate the movement of flood wave in the main stream and the overbank flow inundating into the nearby lowlands. Based on the numerical simulation results, the flooding extents in the basin corresponding to different return periods of flood using existing flood prevention infrastructures were investigated. A detention strategy by lowering the levee along the riparian farmlands was proposed to avoid severe flooding in the densely populated urban areas of the basin. Research findings showed that the proposed detention measure can completely protect the downstream areas from overbank flooding when a flood having 20-yr period occurs, and can effectively alleviate the downstream flooding area from 27.4 to \(7.6\,\hbox {km}^{2}\) for a flood possessing 200-yr period.  相似文献   

Potential Orthopyroxene,Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination   总被引：1，自引：0，他引：1       下载免费PDF全文

Ben‐Xun Su  Xiao‐Yan Gu  Etienne Deloule  Hong‐Fu Zhang  Qiu‐Li Li  Xian‐Hua Li  Nathalie Vigier  Yan‐Jie Tang  Guo‐Qiang Tang  Yu Liu  Kwan‐Nang Pang  Aaron Brewer  Qian Mao  Yu‐Guang Ma 《Geostandards and Geoanalytical Research》2015,39(3):357-369

Over 1400 electron probe and 700 ion probe microanalyses were performed on eleven mineral separates to evaluate their potential as reference materials for in situ Li isotopic determination. Our results suggest the homogenous distributions of major elements, Li and its isotopes for each sample. Hence, these samples are suitable to be used as reference materials for in situ measurements of Li abundance and Li isotopes by secondary ion mass spectrometry (SIMS) or laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). These samples have the advantage of mitigating probable matrix effects during calibration owing to the wide range of compositions. The effect of composition on the δ⁷Li of olivine measured by SIMS is a linear function of composition, with δ⁷Li increasing by 1.0‰ for each mole per cent decrease in forsterite component.  相似文献   

Methods for ultimate limit state assessment of ships and ship-shaped offshore structures: Part II stiffened panels     

Jeom Kee Paik  Bong Ju Kim  Jung Kwan Seo 《Ocean Engineering》2008,35(2):271-280

The present paper is Part II of a series of three papers on methods useful for the ultimate limit state assessment of ships and ship-shaped offshore structures. In contrast to Part I [Paik et al., 2007a. Methods for ultimate limit state assessment of ships and ship-shaped offshore structures: Part I unstiffened plates, Ocean Engineering, doi:10.1016/j.oceaneng.2007.08.004] that deals with unstiffened plates, the present paper (Part II) is focused on methods for the ultimate limit state assessment of stiffened plate structures under combined biaxial compression and lateral pressure actions. The object structure is the bottom part of an AFRAMAX-class hypothetical double-hull oil tanker structure designed by IACS common structural rules (CSR) method, that is the same ship studied in Part I. Three candidate methods, namely ANSYS nonlinear finite element method, DNV PULS method, and ALPS/ULSAP method, are employed for the present study. The results and insights developed from the present study are summarized in terms of ultimate strength characteristics of bottom-stiffened plate structures.  相似文献   

Analysis of human spatial behavior in a GIS environment: Recent developments and future prospects   总被引：1，自引：0，他引：1  

Mei-Po Kwan 《Journal of Geographical Systems》2000,2(1):85-90

In recent years, comprehensive geographic data sets of metropolitan areas and individual-level, georeferenced data are becoming more available to social scientists. At the same time, tools for performing spatial analysis in a GIS environment have also become more available. These developments provide many new opportunities for the analysis and theoretical understanding of disaggregate human spatial behavior. This paper examines how these developments may enable the researcher to represent complex urban and cognitive environments more realistically, and to overcome the limitations of aggregate spatial data framework. It explores their implications for the theoretical and methodological development in geography and other social science disciplines.  相似文献   

Groundwater flow and radioactivity in Namaqualand, South Africa     

Tamiru A. Abiye  Joyce T. Leshomo 《Environmental Earth Sciences》2013,70(1):281-293

The Namaqualand area is located in the Northern Cape Province of South Africa which is characterised by arid climate where groundwater is the only source of water supply for local communities. Extensive groundwater sampling was carried out in the area and the physico-chemical parameters, inorganic constituents, stable isotopes and trace metals were measured. The hydrochemistry of the area indicates dissimilar groundwater composition due to complex geochemical processes where groundwater flow takes place from catchment F30A to the catchment D82B, and the chemistry is controlled primarily by Redox reaction, dissolution and mixing processes. The Br^?/Cl^? ratio revealed that the salinity in the area is derived from seawater mixing, halite dissolution and atmospheric deposition/sea aerosol spray. Under excessive evaporative condition due to climatic aridity, groundwater salinity shows increasing trend. Isotope results show the presence of shallow-weathered zone and deep-fracture controlled circulating groundwater in the crystalline basement aquifer of the area. In comparison to the South African water quality standard, the results obtained for gross alpha activity which could be derived from uranium isotopes show that 41 % of the reported data in the area fall above the drinking water limit.  相似文献   

Temporal variations of reservoir sediment sources in a small mountainous catchment in Korea   总被引：1，自引：0，他引：1  

Jin Kwan Kim  Yuichi Onda  Dong‐Yoon Yang  Min Seok Kim 《地球表面变化过程与地形》2013,38(12):1380-1392

An understanding of the temporal variation in reservoir sedimentation and identification of the main sources of sediment are necessary for the maintenance of sustainable reservoirs. For this purpose, field measurements, sampling, and fingerprinting of reservoir sediment were undertaken from July 2005 to November 2007. Source fingerprinting of reservoir sediment was conducted using cesium‐137 (¹³⁷Cs). The relative contributions of gully bank and forest road, and forest floor material to reservoir sediment were calculated using a mixing model. Bank and forest road material, estimated to make up about 96% of the reservoir sediment, was the dominant source. Enormous reservoir sedimentation, which amounted to about 60% of the total reservoir sedimentation during the observation period, occurred during a heavy rainstorm with an 80‐year recurrence time. To maintain the sustainability of the reservoir in this study, therefore, temporal and spatial preparation strategies for heavy rainstorms and bank and forest road erosion should be considered. However, spatial information on sediment sources from ¹³⁷Cs fingerprinting is limited. To better identify the sediment sources spatially and temporally, further studies applying soil erosion models and more detailed field studies are needed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Influences of spatial distribution of soil thickness on shallow landslide prediction     

Jui-Yi Ho  Kwan Tun Lee  Tung-Chiung Chang  Zhao-Yin Wang  Yu-Hsun Liao 《Engineering Geology》2012

Shallow landslides usually occur during hevy rainfall and result in casualties and property losses. Thus, the possible locations where landslides are likely to occur must be identified in advance in order to avoid or reduce the harm they cause. When performing a slope-instability analysis, soil thickness is an important factor; however, soil thickness information from landslide-prone areas is rarely obtained. The objective of this study is to realize the influences of spatial distribution of soil thickness on shallow landslide prediction. Three different spatial soil-thickness distributions were applied to perform a slope-instability analysis, and uniform-distributed soil thicknesses from 0.4 m to 2.0 m were also applied for comparison. Geomorphologic information and hydrological records from a landslide-prone area in southern Taiwan were collected. Results show that the spatial distribution of soil thickness related to wetness index provides a reasonable estimation in order to avoid an over-prediction for landslide-prone areas or an under-prediction for stable areas. The analytical procedure used in this study is a simple way for assessing hillslope instability for shallow landslide prediction.  相似文献   

Nonlinear analysis of rainfall dynamics in California's Sacramento Valley   总被引：1，自引：0，他引：1  

Bellie Sivakumar  Wesley W. Wallender  William R. Horwath  Jeffrey P. Mitchell  Samuel E. Prentice  Brian A. Joyce 《水文研究》2006,20(8):1723-1736

This study investigates the dynamic nature of rainfall observed at the Sustainable Agriculture Farming Systems (SAFS) site in California's Sacramento Valley, which was established to study the benefits of winter cover cropping in Mediterranean irrigated‐arid systems. Rainfall data of four different temporal scales (i.e. daily, weekly, biweekly, and monthly) are analysed to determine the dynamic nature of precipitation in time. In an arid climate with seasonal precipitation this has large implications for land and water management, both in the short term and in the long term. A nonlinear dynamic technique (correlation dimension method) that uses the phase‐space reconstruction and dimension concepts is employed. Bearing in mind the possible effects of the presence of zeros (i.e. no rain) on the outcomes of this analysis, an attempt is also made to compare the dynamic nature of all‐year rainfall and winter rainfall. Analysis of 15 years of data suggests that rainfall dynamics at this site are dominated by a large number of variables, regardless of the scales and seasons studied. The dimension results also suggest that: (1) rainfall dynamics at coarser resolutions are more irregular than that at finer resolutions; (2) winter rainfall has a higher variability than all‐year rainfall. These results are indeed useful to gain information about the complexity of the rainfall process at this site with respect to (temporal) scales and seasons and, hence, the appropriate model (high‐dimensional) type. However, in view of the potential effects of certain rainfall data characteristics (e.g. zeros, measurement errors, scale effects) on the correlation dimension analysis, the discussion also emphasizes the need for further verification, and possibly confirmation, of these results. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Climate change, ambient ozone, and health in 50 US cities   总被引：2，自引：1，他引：2  

Michelle L. Bell  Richard Goldberg  Christian Hogrefe  Patrick L. Kinney  Kim Knowlton  Barry Lynn  Joyce Rosenthal  Cynthia Rosenzweig  Jonathan A. Patz 《Climatic change》2007,82(1-2):61-76

We investigated how climate change could affect ambient ozone concentrations and the subsequent human health impacts. Hourly concentrations were estimated for 50 eastern US cities for five representative summers each in the 1990s and 2050s, reflecting current and projected future climates, respectively. Estimates of future concentrations were based on the IPCC A2 scenario using global climate, regional climate, and regional air quality models. This work does not explore the effects of future changes in anthropogenic emissions, but isolates the impact of altered climate on ozone and health. The cities’ ozone levels are estimated to increase under predicted future climatic conditions, with the largest increases in cities with present-day high pollution. On average across the 50 cities, the summertime daily 1-h maximum increased 4.8 ppb, with the largest increase at 9.6 ppb. The average number of days/summer exceeding the 8-h regulatory standard increased 68%. Elevated ozone levels correspond to approximately a 0.11% to 0.27% increase in daily total mortality. While actual future ozone concentrations depend on climate and other influences such as changes in emissions of anthropogenic precursors, the results presented here indicate that with other factors constant, climate change could detrimentally affect air quality and thereby harm human health.  相似文献   

Policy at the margins: developing community capacity in a rural Health Action Zone     

Joyce Halliday  Sheena Asthana 《Area》2005,37(2):180-188

The imperative to engage with communities and employ a community development approach is an integral part of the national agenda under New Labour. However, a large part of the literature and experience that informs contemporary policy and practice draws on the urban realm. This paper draws on the evaluation of a rural Health Action Zone to explore the extent to which national policy can facilitate local approaches to community health development within a rural context. Despite avowed support for innovation and evidence-based learning, it finds a continued emphasis on consensual tactics, low-cost solutions and traditional methods of ranking deprivation.  相似文献