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31.
Use of an artificial neural network for analysis of the susceptibility to landslides at Boun,Korea 总被引:13,自引:0,他引:13
Saro?LeeEmail author Joo-Hyung?Ryu Moung-Jin?Lee Joong-Sun?Won 《Environmental Geology》2003,44(7):820-833
The purpose of this study was to develop landslide susceptibility analysis techniques using artificial neural networks and to apply the resulting techniques to the study area of Boun in Korea. Landslide locations were identified in the study area from interpretation of aerial photographs and field survey data. A spatial database of the topography, soil type, timber cover, geology, and land cover was constructed and the landslide-related factors were extracted from the spatial database. Using these factors, the susceptibility to landslides was analyzed by artificial neural network methods. The results of the landslide susceptibility maps were compared and verified using known landslide locations at another area, Yongin, in Korea. A Geographic Information System (GIS) was used to analyze efficiently the vast amount of data and an artificial neural network turned out to be an effective tool to analyze the landslide susceptibility. 相似文献
32.
A.?Kunnath-PoovakkaEmail author D.?Ryu L.?J.?Renzullo B.?George 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(7):1973-1992
An efficient calibration with remotely sensed (RS) data is important for accurate predictions at ungauged catchments. This study investigates the advantages of streamflow-sensitive regionalization on calibration with RS evapotranspiration (ET). Regionalization experiments are performed at 28 catchments in Australia. The catchments are classified into three groups based on annual rainfall and runoff coefficients. Streamflow, RS ET, and a multi-objective RS ET-streamflow calibration are performed using the DiffeRential Evolution Adaptive Metropolis algorithm in each catchment. Simplified Australian Water Resource Assessment-Landscape model is calibrated for a selection of five parameters. Posterior probability distributions of parameters from three calibrations performed at donor catchments in each group are inspected to find the parameter for regionalization in the individual group. In group 1 of wetter catchments, regionalization of parameter FsoilEmax (soil evaporation scaling factor) helps to simplify the calibration without any deterioration in ET, soil moisture (SM) and streamflow predictions. Regionalization of parameter Beta (coefficient describing rate of hydraulic conductivity increase with water content) in group 2 assists to improve the streamflow predictions with no decrement in ET and SM predictions. However, regionalization is not able to provide satisfactory results in group 3. Group 3 includes low-yielding catchments, with average annual rainfall below 1000 mm/year and runoff coefficient less than 0.1, where traditional streamflow calibration also fails to produce accurate results. This study concludes that streamflow-sensitive regionalization is effective for improving the efficacy of RS ET calibration in wetter catchments. 相似文献
33.
A finite-volume method (FVM) using a multi-block grid technique has been applied to investigate the hydrodynamic coefficients and to categorize the two-dimensional flow pattern around a pair of adjacent cylinders (known here after as double cylinders). Matching grids were used at the interface between blocks (cylinders), and the boundary conditions are imposed around the periphery to exchange physical values across the interface. To validate the developed numerical method, a case with laminar viscous flow around a single cylinder was carried out, the results showed good agreement compared to previously published data. Hydrodynamic coefficients, Strouhal number, and stagnation point change were thoroughly investigated as a function of the separation between the two cylinders. It is found that the changes of hydrodynamic coefficients due to variations in separation are well characterized by the five different vortex flow patterns, which can also be used to explain the flow and vortex pattern around the double cylinders. 相似文献
34.
Detecting the intertidal morphologic change using satellite data 总被引:3,自引:0,他引:3
Joo-Hyung Ryu Chang-Hwan Kim Yoon-Kyung Lee Joong-Sun Won Seung-Soo Chun Saro Lee 《Estuarine, Coastal and Shelf Science》2008,78(4):623-632
Previous research has suggested that competitive bottlenecks may exist for the Mediterranean grey mullets (Osteichthyes, Mugilidae) at the fry stage with the exotic Cyprinus carpio (Osteichthyes, Cyprinidae) playing a central role. As a consequence, the structure of grey mullet assemblages at later stages is thought to reflect previous competition as well as differences in osmoregulatory skills. This paper tests that hypothesis by examining four predictions about the relative abundance of five grey mullet species in 42 Western Mediterranean estuary sites from three areas (Aiguamolls de l'Empordà, Ebro Delta and Minorca) differing in the salinity level and occurrence of C. carpio. Field data confirmed the predictions as: (1) Liza aurata and Mugil cephalus were scarce everywhere and never dominated the assemblage; (2) Liza saliens dominated the assemblage where the salinity level was higher than 13; (3) Liza ramado always dominated the assemblage where the salinity level was lower than 13 and C. carpio was present; and (4) Chelon labrosus dominated the assemblage only where the salinity level was lower than 13 and C. carpio was absent. The catch per unit effort of C. labrosus of any size was smaller in the presence of C. carpio than where it had not been introduced, which is in agreement with the juvenile competitive bottleneck hypothesis. Discriminant analysis confirmed that the assemblage structure was linked to the salinity level and the occurrence of C. carpio for both early juveniles and late juveniles as well as adults. The data reported here reveal that the structure of grey mullet assemblages inhabiting Mediterranean estuaries is determined by salinity and competitive interactions at the fry stage. 相似文献
35.
Examining the relationship between wetland alteration and watershed flooding in Texas and Florida 总被引:1,自引:0,他引:1
Samuel D. Brody Wesley E. Highfield Hyung-Cheal Ryu Laura Spanel-Weber 《Natural Hazards》2007,40(2):413-428
Inland flooding remains one of the greatest threats to the safety of human population in the United States (US). While few
large-scale studies exist, the potential role of naturally occurring wetlands in mitigating flood duration and intensity has
been widely discussed. This study examines the relationship between wetland alteration and coastal watershed flooding in Texas
and Florida over a 12-year period. Specifically, we geo-reference wetland alteration permits required under Section 404 of
the US Clean Water Act and correlate the number of granted permits with the degree of flooding measured by stream gauge data.
Results indicate that specific types of federal permits exacerbate flooding events in coastal watersheds while controlling
for various environmental and socioeconomic characteristics. 相似文献
36.
The likelihood ratio, logistic regression, and artificial neural networks models are applied and verified for analysis of
landslide susceptibility in Youngin, Korea, using the geographic information system. From a spatial database containing such
data as landslide location, topography, soil, forest, geology, and land use, the 14 landslide-related factors were calculated
or extracted. Using these factors, landslide susceptibility indexes were calculated by likelihood ratio, logistic regression,
and artificial neural network models. Before the calculation, the study area was divided into two sides (west and east) of
equal area, for verification of the models. Thus, the west side was used to assess the landslide susceptibility, and the east
side was used to verify the derived susceptibility. The results of the landslide susceptibility analysis were verified using
success and prediction rates. The verification results showed satisfactory agreement between the susceptibility map and the
existing data on landslide locations. 相似文献
37.
Characteristics of biomass burning aerosol and its impact on regional air quality in the summer of 2003 at Gwangju, Korea 总被引:1,自引:0,他引:1
The main objective of this study is to investigate the chemical characteristics of biomass burning aerosol and its impact on regional air quality during an agricultural waste burning period in early summer in the rural areas of Korea. A 12-h integrated intensive sampling of biomass burning aerosol in the fine and coarse modes was conducted on 2–20 June 2003 in Gwangju, Korea. The collected samples were analyzed for concentrations of mass, ionic, elemental, and carbonaceous species. Average concentrations of fine and coarse mass were measured to be 67.9 and 18.7 μg m− 3 during the biomass burning period, 41.9 and 18.8 μg m− 3 during the haze period, and 35.6 and 13.3 μg m− 3 during the normal period, respectively. An exceptionally high PM2.5 concentration of 110.3 μg m− 3 with a PM2.5/PM10 ratio of 0.79 was observed on 6 June 2003 during the biomass burning period. The potassium ratio method was used to identify biomass burning samples. The average ratio of potassium in the fine mode to the coarse mode (FK/CK) was 23.8 during the biomass burning period, 6.0 during the haze period, and 4.7 during the normal period, respectively. A FK/CK ratio above 9.2 was considered a criterion for biomass burning event in this study. Particulate matter from the open field burning of agricultural waste has an adverse impact on visibility, human health, and regional air quality. 相似文献
38.
The origin and evolution of mineralizing fluids in the Cretaceous Gyeongsang Basin, Southeastern Korea 总被引:1,自引:0,他引:1
S.-G. Choi S.J. Pak C.S. Kim I.-C. Ryu S.-M. Wee 《Journal of Geochemical Exploration》2006,89(1-3):61
Ferroalloy, base-metal and precious-metal deposits in or around the Gyeongsang Basin, which is located in the Cretaceous volcano-sedimentary terrain at the southeastern Korea, displays a genetic relationship with subvolcanic activities of Late Cretaceous to Tertiary age. Diverse mineralization, which occurs as vein, breccia-pipe, porphyry-style and skarn deposits, took place from 108 to 45 Ma that overlapped with polyphase episodes of igneous activity. Based on the mineralogy, host rock, fluid inclusion and stable isotope data of the deposits, the systematic variation of physicochemical conditions is thought to be due to their relative positions with respect to a magma source that is genetically related to a low to intermediate-sulfidation porphyry system. There appears to be a systematic decrease towards δ18OH2O values from copper (-gold) and ferroalloy deposits through polymetallic to precious-metal ones. However, Cu (-Au) or Fe–Mo–W deposits are proximal to a magmatic source, whereas polymetallic or precious-metal deposits are more distal to transitional. 相似文献
39.
Groundwater and sediment samples (∼ 1 m depth) at sites representative of different groundwater pathways were collected to determine the aqueous speciation of sulfur and the fractionation of sulfur isotopes in aqueous and solid phases. In addition, selected sediment samples at 5 depths (from oxic to anoxic layers) were collected to investigate the processes controlling sulfur biogeochemistry in sedimentary layers. Pyrite was the dominant sulfur-bearing phase in the capillary fringe and groundwater zones where anoxic conditions are found. Low concentrations of pyrite (< 5.9 g kg− 1) coupled with high concentrations of dissolved sulfide (4.81 to 134.7 mg L− 1) and low concentrations of dissolved Fe (generally < 1 mg L− 1) and reducible solid-phase Fe indicate that availability of reactive Fe limits pyrite formation. The relative uniformity of down-core isotopic trends for sulfur-bearing mineral phases in the sedimentary layers suggests that sulfate reduction does not result in significant sulfate depletion in the sediment. Sulfate availability in the deeper sediments may be enhanced by convective vertical mixing between upper and lower sedimentary layers due to evaporative concentration. The large isotope fractionation between dissolved sulfate and sedimentary sulfides at Owens Lake provides evidence for initial fractionation from bacterial sulfate reduction and additional fractionation generated by sulfide oxidation followed by disproportionation of intermediate oxidation state sulfur compounds. The high salinity in the Owens Lake brines may be a factor controlling sulfate reduction and disproportionation in hypersaline conditions and results in relatively constant values for isotope fractionation between dissolved sulfate and total reduced sulfur. 相似文献
40.
Geospatial blending to improve spatial mapping of precipitation with high spatial resolution by merging satellite‐based and ground‐based data
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Estimating accurate spatial distribution of precipitation is important for understanding the hydrologic cycle and various hydro‐environmental applications. Satellite‐based precipitation data have been widely used to measure the spatial distribution of precipitation over large extents, but an improvement in accuracy is still needed. In this study, three different merging techniques (Conditional Merging, Geographical Differential Analysis and Geographical Ratio Analysis) were used to merge precipitation estimations from Communication, Ocean and Meteorological Satellite (COMS) Rainfall Intensity data and ground‐based measurements. Merged products were evaluated with varying rain‐gauge network densities and accumulation times. The results confirmed that accuracy of detecting quantitative rainfall was improved as the accumulation time and network density increased. Also, the impact of spatial heterogeneity of precipitation on the merged estimates was investigated. Our merging techniques reproduced accurate spatial distribution of rainfall by adopting the advantages of both gauge and COMS estimates. The efficacy of the merging techniques was particularly pronounced when the spatial heterogeneity of hourly rainfall, quantified by variance of rainfall, was greater than 10 mm2/accumulation time2. Among the techniques analysed, Conditional Merging performed the best, especially when the gauge density was low. This study demonstrates the utility of the COMS Rainfall Intensity product, which has a shorter latency time (1 h) and higher spatio‐temporal resolution (hourly, 4 km by 4 km) than other widely used satellite precipitation products in estimating precipitation using merging techniques with ground‐based point measurements. The outcome has important implications for various hydrologic modelling approaches, especially for producing near real‐time products. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献