Flood Hazard Assessment on Cultural Heritage-Jungrimsa’s Pagoda, Buyeo, Korea

Joo Jaewon and Lee Hyosang

The Jungrimsa’s Pagoda (built in the 5th century) is one of the major heritages of the Baekje dynasty (BC18-AC660). In this study, the flood hazard of Jungrimsa’s pagoda is assessed based on the flood hazard assessment tools with flood hazard assessment scenarios. The flood hazard assessment tools are comprised of a rainfall runoff model (HEC-HMS), a river hydraulic model (HEC-RAS), a flood inundation model and a geographical information system. A flood hazard is indicated with the expected inundated map of 12 flood hazard scenarios. The most severe scenario is the case of a combination of a case of high tide in the estuary barrage on the West Sea and a case of maximum discharge from Daecheong Dam (which is located in the upper Geum River) and a case of breaking the embankment in Buyeo. The inundation risk was estimated based on the situation of a breaking of the embankment in the Geum River with these extreme scenarios. However, the results of this flood hazard assessment show that Jungrimsa’s Pagoda is safe from all flood hazard scenarios. This study suggests a direction for the flood hazard management of the architectural heritage site based on scenario analysis.

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Calibration of Blaney–Criddle equation for estimating reference evapotranspiration in semiarid and arid regions

Heydari Mohammad Mehdi and Heydari Morteza

Penman-Monteith (FAO-56 PM) equation is suggested as the standard method for estimating evapotranspiration by the International Irrigation and Drainage Committee and FAO. On the other hand, the Blaney–Criddle (BC) temperature-based equation is an alternative and simple method compared with the FAO-56 PM equation. In the present study, the original coefficients of BC equation (a and b) were calculated and were calibrated for spatial and temporal calibration at each station for each month based on the FAO-56 PM method for estimating reference evapotranspiration (ET0) from 15 meteorological stations in central Iran (about 170000 km2) under semi-arid and arid conditions. The values of a and b in BC equation were negative and positive for all months of any station. Highest and lowest a values were obtained in December and August respectively. December showed the lowest b values while August showed the highest. Therefore, the values of a and b were greater in cold and warm months of the year. After calibration, the root mean square error (RMSE), mean bias error (MBE) and percentage error (PE) values were obtained lower than 0.50 mm day-1, 0.015 mm day-1 and 10% for the whole stations and months respectively. The values of bcal were proportional and inversely to acal. The ET0 values based on the calibrated Blaney–Criddle equation (CBC) were better than the results of the BC equation when compared to the FAO-56 PM equation as the reference model.

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Quantitative assessment of landslide susceptibility on a regional scale using geotechnical databases developed from GIS-based maps

Park D.W., Lee S.R., Nikhil N.V., Yoon S. and Go G.H.

A practical application of a simple and economical solution to landslide susceptibility zonation using a geographic information system (GIS) was performed in Woomyeon Mountain, Seoul, Korea. The regional, physically based stability model of TRIGRS was used as the landslide susceptibility analysis. The accuracy of the model results depends primarily on a detailed knowledge of the study site and on the quality of the input parameters. However, the input data for the model is difficult to obtain because it not only requires test-based results but also spatial data. An alternative application method for a physically based model in wide area using either GIS-based soil textures or geology maps is proposed for landslide susceptibility zonation. From a spatial database, the input data for the TRIGRS model including the material strength and hydraulic properties were extracted. The validation results exhibited satisfactory agreement between the calculated susceptibility zonation using different input layers and the existing landslide location on the landslide inventory. The use of these types of spatial maps linked with suggested geotechnical information enables reasonable estimation of the regions susceptible to landslides. Although the accuracy of the proposed model needs improvement, this approach is very useful for preliminary spatio-temporal assessments over large areas.

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An Experimental Study on the Hydraulic Performance of Wharf Structure with Plain and Partially Perforated Walls

Lee Jong-In and Shin Sungwon

In the present study, the laboratory experiments were conducted in three-dimensional wave basin to investigate the applicability of a perforated wall structure to a wharf structure and the capabilities of wave reflection, stem wave evolution and wave overtopping controls. Four different random wave conditions were tested considering non-overtopping and overtopping cases. The perforated wall reduced reflection coefficients by 60% of those from the plain wall in non-overtopping cases. The perforated wall structure also reduced the stem wave evolution effectively in non-overtopping cases compared to the plain wall structure while there was no big difference between the two structures in overtopping cases. On the other hand, the performance of this structure in terms of wave height variation in normal direction to the wall was not as effective in overtopping cases as in non-overtopping cases. Unlike the results in terms of wave reflection and stem wave evolution, the perforated wall structure reduced the overtopping rates a lot more compared to the plain wall structure when the slit location was below the mean water level. Therefore, the perforated wall structure can be effective as a wharf structure for both non-overtopping and overtopping cases. This data set can contribute to the numerical model verifications.

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Experimental Study on Remolded Saturated Loess Liquefaction by Shear Wave Velocity

Zhou Yun-dong

Currently, there is an increasing trend of seismic activities all over the world and earthquake-induced liquefaction occurs frequently. Loess covers about 9.3% of the land area around the world. Based on long-term field investigation and laboratory tests by some scholars, loess liquefaction can occur under certain conditions. However, the existing research results are limited to sand liquefaction and the results of loess liquefaction are seldom. Shear wave velocity of soil is directly in connection with dynamic shear modulus and the corresponding damping characteristics. In this paper, GDS bidirectional cyclic triaxial system equipped with piezoelectric bend elements is adopted and undrained cyclic triaxial tests are conducted on remolded saturated Xi'an loess by shear wave velocity. The liquefaction characteristic of loess during the process of cyclic loading is analyzed and different test parameters are controlled to investigate the influence of seismic loading on shear wave velocity. Based on the test results, the formula of critical shear wave velocity is obtained and the relation between the shear modulus and the liquefaction resistance is established. Moreover, a method of evaluation of saturated loess liquefaction by shear wave velocity is proposed. The derived method is of much importance to evaluate liquefaction of loess site in practical applications.

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Monsoon driven seasonal variations of nearshore waters of Palk Bay, Bay of Bengal, India

Kathiravan K., Usha Natesan and Vishnunath R.

Rameswaram Island, located on the southeast coast of India in Tamil Nadu, is the main pilgrimage site influenced by anthropogenic intercessions. Assessment of physico-chemical characteristics of nearshore water quality was carried out during April 2011 – March 2012 to explicate its quality variations. Principal component analysis was applied to extract the total variability and to obtain interrelationships between physico-chemical parameters. High loadings of pH, temperature, SPM, salinity, DO, BOD, nutrient species of nitrogen, phosphorus and chlorophyll were acquired through PCA. High deterioration of the water quality is observed during summer.

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A study on Rainfall Variability and its pattern in a Semi Arid Basin, Tamil Nadu, India

Shimola K. and Krishnaveni M.

In most of semi arid basins whose economy mainly depends on rainfed agriculture, inter-annual and seasonal rainfall variability is high and droughts are frequent in this region. This paper examines the rainfall characteristics of Vaippar basin using standard rainfall statistical descriptors for 10 rainguage stations with 35 years of monthly rainfall data. The spatial distribution of annual rainfall was varied from 970 to 550 mm where northeast monsoon contributes more than 75% of annual rainfall with high to very high monthly concentration. Annual rainfall has shown negative anomalies for 1950’s and ends around early 1970’s which correspond to severe droughts in northeast parts of the basin. The standardized anomaly indices of annual rainfalls for each rainfall station exhibited that the basin rainfall was more fluctuating in character. An analysis of excessive and deficient rainfall years based on the departure from normal showed 66% basin average rainfalls are within the normal range. The seasonality index which is a measure of distribution of rainfall is used to classify the rainfall regime while markedly seasonal with a long dry season rainfall regime was pronounced in this basin. The onset and end date of the northeast monsoon seasons plotted using the box and whiskers techniques showed a shift in onset and end date with the contraction of the length of growing period due to early cessation of rainfall events. However, a decrease in number of rainy days is observed in most of the stations. Studying the rainfall characteristics and pattern has strong implications for managing water resources and drought management under climate change scenario.

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Rock slope fracture process using a combined block theory and discontinuous deformation analysis approach based on the strength reduction method

Wang Shuhong, Ni Yong, Viete Daniel Ricardo and Gamage Ranjith Pathegama

Blocky rock masses are commonly seen in engineering as undesirable. The geometrical characteristics of such blocky rocks are irregular and the use of only one method to simulate and analyze the rock mass can lead to inaccuracy in understanding stability behavior. Methods for stability analysis of blocky rock masses are increasingly using combinations of analytical approaches. Geotechnical problems involving blocky rock masses must consider the nature of the discontinuities that form the rock blocks and a tendency toward large deformation along these. New software for simulation and analysis of blocky rock (based on block theory),GeoSMA-3D is presented for stability analysis in three dimensions. The software is partnered with discontinuous deformation analysis (DDA), to identify all potential slip failure surfaces and obtain safety factors for them. The method first discretizes the model by addition of a large amount of ‘invented’ joints. These virtual joints cut the rock mass into many small block units for which the mechanical parameters of the virtual joints are the same as the intact rock. Secondly, the cohesion and friction coefficient for the real (and not the invented) joints are systematically varied during trial calculations which use DDA to stimulate the failure process. After some amount of trial, the structure comes to a critical (failed) state from which the critical slip failure surface and deformation mode can be identified and the reduction coefficient (the safety factor) can be obtained.

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Spatial distribution of scatterers in the crust of Kachchh region, Western India by inversion analysis of coda envelopes

Sharma Babita and Rastogi B. K.

The three-dimensional spatial distribution of relative scattering coefficients is estimated in the Kachchh region, western India, by means of an inversion technique applied to coda wave envelopes. Data used consisted of selected vertical-component, broad band recordings from 438 earthquakes with moment magnitudes Mw ranging from 1.6 to 4.2 and epicentral distances up to 235 km recorded by the Institute of Seismological Research (ISR) seismic network. The results of the inversion analysis yield relative scattering coefficient estimates between ~1.3 and ~0.8. Most of the analyzed region reveals small spatial perturbations of the scattering coefficient of the order of ±16%, thus suggesting a uniform distribution of scattering coefficients in the lithosphere beneath Kachchh region for the scale length of the analyzed frequencies between 1 and 2 Hz. This uniformity is broken by the presence of some strong scattering areas distributed in several clusters throughout the region. Moho discontinuity in this region is imaged at average depths between 32 and 42 km. Also it is clear that in the Kachchh region the Moho discontinuity is highly disturbed which may be due to the high velocity body in the lower crust and upper mantle which is consistent with similar studies in the area.

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Research on the relevance between flood disaster and fractal characteristics of river networks- A Case Study of Hangzhou, CHINA

Zhang Shi-xia , Wang Zi-wen , Zhang Shi-min and Yi Zu-hong

Flooding is a product of the combination with climate and watershed geomorphology. And the geomorphic feature of river networks played a role for the formation of the flood. The aim of this paper is to explore the relevance between morphological characteristics of different drainage and the density of flood-happens and to predict the impact of change of river networks on flood disasters. For such purposes, Hangzhou (Zhejiang, China) was selected being a site that suffers from severe flooding. The fractal dimension was computed for the eight sub rivers by using the box-counting method based on the river network map. Then relevance-based a model was built by the correlation analysis within the fractal dimension and floods. Study found that good negative correlation exits between drainage fractal dimension and the density of floods disaster. That is to say, smaller the fractal dimension is, more floods happen and vice versa. Then, by using the model, the influence of network changing caused by rapid urbanization to flooding was analyzed in two typical regions. Results showed that the factors such as precipitation, vegetation under the condition of little change, change in morphological characteristics of rive network, reduction of fractal dimension are the important causes leading to flood-happens.

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Effects of moisture on characteristics of coal-bed methane seepage

Liu Zhen, Li Zenghua and Yang Yongliang

Gas extraction from water-injected-boreholes of coal seam has been widely applied for the prevention of coal and gas outburst in China. It includes injecting water into boreholes and extracting gas from the water-injected boreholes. In the water-injection process, water is pressed into the cleat around boreholes and then seep into the pores around the cleat under the action of capillary forces. In the gas extraction process, methane initially adsorbed on the coal matrix is desorbed and diffused into cleat and then spread into boreholes driven by pressure. Although it is well known that the injected water could affect gas adsorption, desorption, diffusion and seepage, the mechanisms that moisture affects the characteristics of methane seepage in coal are rarely reported. In this study, we presented a method studying the impact of moisture on gas seepage in coal seam, established an experimental system for steady radial seepage flow and used it to investigate the effects of water on the capacity of CH4 adsorption and the characteristics of gas seepage in coals from Huaibei Coal Mine, China. The results showed that 1) water content in coal significantly impacts CH4 adsorption capacity and permeability. At constant adsorption pressure, CH4 adsorption capacity gradually decreases with moisture content increasing; based on which a mathematical model for the relationship of the adsorption capacity to the pressure and the moisture content is presented; 2) affected by the water-induced coal swelling and the competitive adsorption between water and CH4, water content will impact CH4 permeability in coal-bed. CH4 permeability decreases with moisture content increasing especially at low gas pressure; based on which a CH4 permeability-predicting model is established.

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