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21.
Landslide susceptibility assessment in the İzmir (West Anatolia,Turkey) city center and its near vicinity by the logistic regression method 总被引:1,自引:1,他引:0
A landslide susceptibility assessment for İzmir city (Western Turkey), which is the third biggest city of Turkey, was performed
by a logistic regression method. A database of landslide characteristics was prepared using detailed field surveys. The major
landslides in the study area are generally observed in the field, dominated by weathered volcanics, and 39.63% of the total
landslide area is in this unit. The parameters of lithology, slope gradient, slope aspect, distance to drainage, distance
to roads and distance to fault lines were used as variables in the logistic regression analysis. The effect of each parameter
on landslide occurrence was assessed from the corresponding coefficients that appear in the logistic regression function.
On the basis of the obtained coefficients, lithology plays the most important role in determining landslide occurrence and
distribution. Slope gradient has a more significant effect than the other geomorphological parameters, such as slope aspect
and distance to drainage. Using a predicted map of probability, the study area was classified into five categories of landslide
susceptibility: very low, low, moderate, high and very high. Whereas 49.65% of the total study area has very low susceptibility,
very high susceptibility zones make up 11.69% of the area. 相似文献
22.
23.
A solid waste disposal site selection procedure based on groundwater vulnerability mapping 总被引:2,自引:0,他引:2
In this study, a new, GIS-based solid waste site selection tool (DUPIT) is introduced to obtain a systematic and unbiased
methodology during the evaluation phases of alternative solid waste disposal areas with regards to vulnerability to groundwater
pollution. The proposed tool is an index technique based on the linear combination of five different hydrogeological parameters
including Depth to groundwater table, Upper layer lithology, Permeability of the unsaturated zone, Impermeable layer thickness and Topographic slope. Five different categories are developed to classify each alternative based on the suitability of the site
for a solid waste disposal area. As a result, each site is ranked according to the contamination risks for groundwater resources.
The proposed technique is applied to the District of Torbali near Izmir, Turkey to determine the most appropriate solid waste
disposal site location. The Torbali application is implemented by using a GIS database developed for the area. Based on the
results of this application, the best alternative solid waste disposal site for Torbali is selected to be located in the northern
portions of the city where the groundwater table is deep, the permeability is low and the topographic slope is mild. 相似文献
24.
S?cak Çermik (Sivas) is an important geothermal and recent travertine formation area in Central Anatolia. The majority of travertines found in the region comprise fissure-ridge type travertines according to morphological classification. At the location called Tepe Çermik within the travertine area, fill containing fossil bone fragments of Equus sp., Bovidae and other abundant animals formed within the fracture axis of a N–S striking fissure-ridge travertine developed under control of tectonic forces. The finds of these fossils in fissure-ridge travertines linked to tectonic forces indicates formation of a unique fossil environment created under the control of these forces. The Accelerator Mass Spectrometry Radiocarbon Dating analyses of fossils from the study area determined the fills were older than 43,000 years. The U/Th age of a sample from the most recently-formed banded travertine in the axis of the fracture was identified as 278,540 ± 18,436 years. As a result, the ages of fossils found within this fill are thought to be between 43,000 and 278,540 ± 18,436 years old. The high amount of perissodactyla and artiodactyla fossils found within fill in the axis of the fissure-ridge travertine probably indicates the presence of hominids who chose the region for hunting or settlement. The Equus sp. and Bovidae fossil samples found in the axis of the fracture indicate that in the dry and cold glacial period the paleogeography in a large portion of Anatolia comprised desert-like steppe. 相似文献
25.
A two‐phase research program has been undertaken to investigate fundamental natural periods of concentrically braced frames (CBFs) designed according to Eurocode 8 (EC8). In the first phase of the program, over 83,700 buildings were designed, and the accuracy of the lower bound expressions given in well‐known design specifications was evaluated. The results indicated that the lower bound expressions given in EC8 and National Building Code of Canada (NBCC) are acceptable. Although all structures had periods longer than the ones estimated by the EC8 expression, a few structures had shorter periods than the ones estimated by the NBCC expression. In general, the lower bound expressions given in EC8 and NBCC were found to provide over conservative estimates for most cases. In the second phase of the program, a simple hand method was developed to estimate the fundamental natural periods of CBFs designed to EC8. This method requires the use of inelastic top story drift ratio as a parameter to quantify stiffness characteristics. The drift ratios were extracted from the design pool developed as a part of the first phase and represented by simple mathematical relationships. Evaluation of the proposed method indicated that the method is accurate in providing estimates of the fundamental period. To safeguard against providing unconservative estimates, the method was modified to arrive at a new lower bound expression, which significantly improves the estimates compared with the ones provided by the existing expressions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
26.
Oya Algan M. Nam?k Yalç?n Yücel Y?lmaz Elmas K?rc?-Elmas Özlem Bulkan Cem Gazio?lu Mehmet Ali Polat 《Quaternary Research》2011,76(1):30-45
An extensive rescue excavation has been conducted in the ancient harbor of ?stanbul (Yenikap?) by the Sea of Marmara, revealing a depositional sequence displaying clear evidence of transgression and coastal progradation during the Holocene. The basal layer of this sequence lies at 6 m below the present sea level and contains remains of a Neolithic settlement known to have been present in the area, indicating that the sea level at ~ 8-9 cal ka BP was lower than 6 m below present. Sea level advanced to its maximum at ~ 6.8-7 cal ka BP, drowning Lykos Stream and forming an inlet at its mouth. After ~ 3 cal ka BP, coastal progradation became evident. Subsequent construction of the Byzantine Harbor (Theodosius; 4th century AD) created a restricted small basin and accumulation of fine-grained sediments. The sedimentation rate was increased due to coastal progradation and anthropogenic factors during the deposition of coarse-grained sediments at the upper parts of the sequence (7th-9th centuries AD). The harbor was probably abandoned after the 11th century AD by filling up with Lykos Stream detritus and continued seaward migration of the coastline. 相似文献
27.
Purification of diatomite powder by acid leaching for use in fabrication of porous ceramics 总被引:1,自引:0,他引:1
This study presents an investigation of the purification of a raw diatomite by acid leaching conducted in hot solution (75 °C and 5 M HCl) for long periods up to 240 h, evaluates the use of these purified powders in the fabrication of porous materials, and examines their porosities. The treatment for 1 h increased the specific surface area of diatomite from 189 m2/g to 222 m2/g, but the SiO2 content of 78.66% was still low. Material leached for a relatively short time shows an amorphous phase with quartz and plagioclase phases and the plagioclase is removable at longer leaching times during which no disruptive effect on the fine microscopic pores of the particles was observed. Thus, the diatomite based powders have potential use in the fabrication of porous coating as a membrane-separating layer: sintering at a relatively high temperature (1300 °C) still showed a significantly high apparent porosity of 48%. 相似文献
28.
A new analysis technique has been proposed for interpreting transient step-drawdown test data. The proposed method is based on taking the derivative of the drawdown with respect to time for the entire pumping test period to eliminate the time-independent well-loss terms. The derivative function is subsequently integrated to obtain the time-dependent aquifer drawdown as a continuous function. The well-loss parameters are then obtained with higher accuracy once the aquifer behavior is identified. The proposed method is applicable for analyzing data obtained not only from ideal confined aquifers but also from other aquifer types (i.e. unconfined) and non-ideal aquifers (i.e. heterogeneous). The technique was tested for synthetically generated and field data; the proposed approach was noted to provide accurate aquifer and well-loss parameter estimates. The results of the proposed method were compared with those of some of the existing methods for analyzing step-drawdown test data and were found to be more reliable and robust. 相似文献
29.
Parameter Estimation for Step-Drawdown Tests 总被引:1,自引:0,他引:1
Cem B. Avci 《Ground water》1992,30(3):338-342
30.
Dev K. Niyogi Janet M. Bandeff Cem Selman Drew E. Menke 《Aquatic Sciences - Research Across Boundaries》2010,72(2):203-212
We examined nutrient flux, uptake, and transformation along a spring-fed stream in the Ozark region of Missouri, USA, over
the year 2006. Water in Mill Creek originates from several springs, with a single spring contributing over 90% of the stream
discharge during much of the year of study. Soluble reactive phosphate concentrations were usually low (<10 μg L−1) along Mill Creek, but peaked during high discharge. Concentrations of dissolved inorganic nitrogen (DIN) were relatively
high in the spring water, mainly as nitrate, but usually declined across a small pond and the 10-km length of Mill Creek.
During low flows in summer and early autumn, the stream removed over 300 μg L−1 of DIN over its 10-km length, or about 80% of the initial amount. DIN retention along the stream, as a percentage of the
DIN upstream, was related mainly to discharge, with higher flows having much higher DIN concentrations. The net uptake rate
of DIN uptake was 0.91 μg m−2 s−1 in the stream during summer baseflow. The uptake rate declined downstream for different reaches and was closely related to
DIN concentration. In experimental channels, uptake by epilithic algae was one significant sink for nitrate-N in Mill Creek.
In 2006, inorganic nutrient export during a single day after a spring storm was similar to export during 40–100 days of low
flow conditions in summer and early autumn. Our results suggest that significant nutrient retention can occur during baseflow
periods via biological uptake, whereas substantial export occurs during high flow conditions. 相似文献