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61.
Short-term geomorphic and hydrologic effects of subsidence induced by longwall mining under Burnout Creek, Utah were evaluated.
During the year after longwall mining, 0.3–1.5 m of subsidence was measured near impacted reaches of the mountain stream channel.
The major channel changes that occurred in a 700-m reach of Burnout Creek that was subsided from 1992 to 1993 were: (1) increase
in lengths of cascades and to a lesser extent glides; (2) increases in pool length, numbers and volumes; (3) increase in median
particle diameter of bed sediment in pools; and (4) some constriction in channel geometry. Most of the changes appeared short-lived,
with channel recovery approaching pre-mining conditions by 1994. In a 300-m reach of the South Fork that was subsided from
1993 to 1994, only channel constriction was observed, although any impacts on pool morphology may have been confounded by
heavy grazing in the riparian reaches during the dry summer of 1994. Similar near-channel sedimentation and loss of pool volume
between 1993 and 1994 were noted throughout Burnout Creek and in adjacent, unmined James Creek. Subsidence during the 3-year
period had no effect on baseflows or near-channel landslides.
Received: 10 April 1998 · Accepted: 21 September 1998 相似文献
62.
The purpose of this work is to select the optimal spectral decomposition (SD) method for channel detection in the Miocene strata of the Carpathian Fordeep, SE Poland. For analysis, two spectral decomposition algorithms were tested on 3D seismic data: the first, based on Fast Fourier Transform (FFT), and second, on Complete Ensemble Empirical Mode Decomposition (CEEMD). Additionally the results of instantaneous frequency (IF) were compared with the results of peak frequency (PF) computed after the CEEMD. Both algorithms of SD enabled us to interpret channels, but the results are marginally different, i.e. the FFT shows more coarse, linear structures, that are desirable for channel interpretation, whereas the CEEMD does not highlight these structures as clearly and shows more, what the authors believe to be, noise. 相似文献
63.
Barbora Topinkova Kamil Nesetril Josef Datel Ondrej Nol Petr Hosl 《Hydrogeology Journal》2007,15(5):961-976
The geochemical processes, water–rock interactions and stable isotopes distribution (δ13C of DIC and δ18O and δ34S of \({\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}} \)) were investigated in the gasoline-contaminated aquifer at the Hnevice site, 50 km northwest of Prague, Czech Republic. Diesel, gasoline and oil leaks originate from a large fuel storage area causing heavy contamination of the saturated and unsaturated zones in an area of about 0.7 km2. Groundwater investigations were conducted using five multilevel sampler wells with emphasis on redox parameters and degradation by-products and a solid-phase study focused on iron speciation and determination of principal and secondary minerals. Based on the study of groundwater and solid-phase geochemistry, four different geochemical zones were described. Zone I is thought to be background consisting of an aerobic aquifer and the absence of reduced species in significant concentrations. Zone II is situated in the plume core with methanogenic, sulphate and iron-reducing conditions accompanied by ankerite and kutnahorite precipitates and significant depletion of the oxidation capacity of the aquifer. Zone III is a mixing (corona) zone, situated at the fringe of the plume with high biodegradation rates and Fe(III)-precipitants. In zone IV, reoxidation of Fe(II) minerals (with e.g. the occurrence of psilomelane and cornelite) is typical. 相似文献