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31.
32.
Evaluating proxies for estimating subaerial beach volume change across increasing time scales and various morphologies
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Proxies, such as changes in beach profiles and shoreline positions, are commonly used in management and research for estimating changes in subaerial beach volume; however, the accuracy of these proxies across increasing time scales and complex morphologies is unclear. Volume changes associated with along‐beach morphologic variability may not be captured well by changes in profiles, while volume changes associated with across‐beach morphologic variability may not be captured well by measuring shoreline change. This study assesses the impacts of morphologic variations, associated with beach cusps and nourishment material, on volume change estimates from profiles and shoreline change at 0.5 to 3.5 year time periods. Results indicate that profiles spaced ≥ 150 m apart and the shoreline‐change proxy will likely estimate volume change inaccurately over periods ≤ 1 year at beaches that are consistently eroding or accreting and contain cusps. However, over longer time periods (1–3.5 years), estimates of volume change from both proxies improved at those types of beaches. Volume changes at the edges of nourishment areas are not captured well by profiles. When the nourishment material is graded to a ramped morphology, which minimizes across‐beach morphologic variability, the shoreline‐change proxy does accurately estimate volume changes. Both proxies estimate volume changes inaccurately at beaches where volume changes oscillate between erosion and accretion on both short and long time scales because the magnitude of small‐scale changes in volume from the formation and erosion of morphologic features, such as cusps and berms, will always be similar to the longer‐term net volume change. This study suggests that decadal records of shoreline change, which are commonly developed using aerial photography, can be used to help identify the best proxy for estimating volume change; however, recent anthropogenic modifications that impact patterns of beach sedimentation, including nourishment, terminal groins, and inlet‐channel dredging, makes decadal records less useful. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
33.
E. Aghaarabi F. Aminravan R. Sadiq M. Hoorfar M. J. Rodriguez H. Najjaran 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(3):655-679
This paper presents the use of two multi-criteria decision-making (MCDM) frameworks based on hierarchical fuzzy inference engines for the purpose of assessing drinking water quality in distribution networks. Incommensurable and uncertain water quality parameters (WQPs) at various sampling locations of the water distribution network (WDN) are monitored. Two classes of WQPs including microbial and physicochemical parameters are considered. Partial, incomplete and subjective information on WQPs introduce uncertainty to the water quality assessment process. Likewise, conflicting WQPs result in a partially reliable assessment of the quality associated with drinking water. The proposed methodology is based on two hierarchical inference engines tuned using historical data on WQPs in the WDN and expert knowledge. Each inference engine acts as a decision-making agent specialized in assessing one aspect of quality associated with drinking water. The MCDM frameworks were developed to assess the microbial and physicochemical aspects of water quality assessment. The MCDM frameworks are based on either fuzzy evidential or fuzzy rule-based inference. Both frameworks can interpret and communicate the relative quality associated with drinking water, while the second is superior in capturing the nonlinear relationships between the WQPs and estimated water quality. More comprehensive rules will have to be generated prior to reliable water quality assessment in real-case situations. The examples presented here serve to demonstrate the proposed frameworks. Both frameworks were tested through historical data available for a WDN, and a comparison was made based on their performance in assessing levels of water quality at various sampling locations of the network. 相似文献
34.
Judith Hebelen Rodriguez Eduardo Daniel Wannaz María Luisa Pignata Andreas Fangmeier Jürgen Franzaring 《洁净——土壤、空气、水》2012,40(12):1315-1319
In order to study the pollution gradient in the vicinity of a large aluminium production facility in Patagonia (Argentina), a passive biomonitoring was performed employing foliage from three tree species. Primary scope was to identify pollution gradients and to select suitable tree species which can be used as biomonitor plants in the study area. Therefore, leaves of Eucalyptus rostrata, Populus hybridus and different needle ages of Pinus radiata were collected at different distances from the industry and the fluoride concentration was analysed in washed and unwashed samples in order to determine the amount of external fluoride. Washing reduced the F‐concentrations by 24, 39 and 51% on average in E. rostrata, P. hybridus and P. radiata, respectively, indicating that species‐specific characteristics determine the accumulation and wash‐off of dust‐associated fluorine. F‐concentrations varied from 6 to 3652 ppm F in unwashed samples indicating a steep pollution gradient in the study area. The influence of F‐emissions was discernible in all samples up to a distance of 3500 m from the smelter. E. rostrata accumulated more fluorine than the other species at equal distance from the emission source. The present study confirms that aluminium smelting results in high F deposition in the study area. Establishing a biomonitor network around large emitters is suitable and feasible to evaluate the efficiency of air control measures. 相似文献
35.
Mauricio Herrera Rodriguez 《GeoJournal》2012,77(5):633-649
This paper argues that the changing land tenure legislation in Mexico is a concrete reflection of generalized societal attitudes towards indigenous and traditional peasants. It contends that the 1992 neoliberal land-reform mimics the progress-oriented liberal project of the ninettenth century and continues a market-centered modernization process underway since the 1940s, which has been legitimized by an overt institutional disdain and discrimination against indigenous people, peasants and their ways of life. It concludes that this process of assimilation or eradication of traditional agro-ecosystems, cultural diversity and social organization will further increase the vulnerability of Mexican peasants to economic and cultural change. As peasants engage in market-controlled business ventures in the rural areas, migrate to cities, rent or sell their lands, they simultaneously adapt to new values and envision new strategies for subsistence that are increasingly mediated by political-economic forces largely beyond their sphere of influence. 相似文献
36.
David Washington Daniel Rodriguez Vincent Ogunro 《Geotechnical and Geological Engineering》2011,29(1):13-17
The monitoring operation of an older impoundment (such as dams and waste barrier materials) during the service life of the
structure cannot be overemphasized. Since older infrastructures seem to be more susceptible to piping and seepage failure,
their construction design should be analyzed and monitored at places where a potential problem could occur. Once an impoundment
is constructed without adequate filters layers and foundation treatments, then the prevention of piping or seepage may require
an effective approach to constructing a cut-off wall to prevent eventual failure. In order to identify and understand theses
failure modes, it is important to identify the physical parameters of the impoundment system, such as the zones of various
soil gradations, the compaction of these zones, the hydraulic conductivity, the compatibility of the soil formations within
and beneath the core or liner, as well as the cohesive and dispersive properties of soils at various location within the structure.
Once these parameters are known and quantified, an adequate assessment of the structure’s susceptibility to piping or contaminant
transport can be established. This type of an analysis will enable the proper design of a cut-off wall and predetermine the
effectiveness of its long-term performance. The Vermont Waterbury Dam (built in 1938) is example of seepage related problem
that implemented a cut-off wall design to prevent piping paths from undermining the structure. In this case, some forensic
sampling had to be performed and the parameters of the soils as just mentioned were key factors in determining the wall design.
In this paper, the Waterbury dam rehabilitation is investigated as case studies, in order to better understand how older designs
and poor construction of impoundments can lead to piping condition in dams as well as failures in waste barrier systems. The
Secant Cut-off wall (constructed at Waterbury Dam) is mentioned as a corrective measure taken for this dam and there is a
brief discussion as to how this construction rehabilitation technique can be applied to waste barrier impoundments. 相似文献
37.
38.
P. López de Coca A. Rolland R. Garrido E. Rodriguez 《Astrophysics and Space Science》1990,169(1-2):211-213
Empirical period-luminosity-colour (P-L-C) relations are obtained for the four lowest modes corresponding to radial pulsations. Agreement with predicted values indicates that, in general, both Strömgren photometric calibration and pulsation theory work well for these stars.Paper presented at the 11 th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
39.
40.
Precipitation records from Salamanca (Spain) are being analyzed to detect temporal oscillations. This paper shows a method to identify these signals in order to determine the behaviour of the precipitation time series in this region. 相似文献