• Title/Summary/Keyword: Continuous Rainfall

Search Result 216, Processing Time 0.029 seconds

Numerical Analysis of the Seepage from and Stability of a Mine Waste-dump Slope during Rainfall (강우시 광산폐기물 적치사면의 침투 및 안정성에 대한 수치해석)

  • Song, Young-Suk
    • The Journal of Engineering Geology
    • /
    • v.25 no.1
    • /
    • pp.57-66
    • /
    • 2015
  • A numerical analysis was performed of the seepage from and stability of a mine waste-dump slope in Imgi, Busan, considering rainfall intensity. The 40-45° slope angle of the waste dump is relatively steep, and the depth of the waste dump down to bedrock is 7-8 m. The groundwater level was 6.6 m below the surface. Various laboratory tests on samples obtained from the waste dump were performed to determine the input data for seepage and stability analyses of the waste-dump slope during rainfall. The results of seepage analysis for various rainfall intensities using the SEEP/W program show that the wetting front moved down with increasing rainfall duration. When the rainfall intensity was > 50 mm/ hour and the duration was > 24 hours, the waste dump became fully saturated because the wetting front reached the groundwater level. The results of slope stability analysis coupled with seepage analysis using the SLOPE/W program show that the safety factor of the slope decreased as the wetting front moved down due to rainfall infiltration. After continuous rainfall for 5-6 hours, the safety factor of the slope suddenly decreased but then recovered and converged. The sudden decrease was induced by an increase in pore-water pressure and a decrease in matric suction down to a certain depth as the wetting front approached the potential sliding surface.

A correlation analysis between state variables of rainfall-runoff model and hydrometeorological variables (강우-유출 모형의 상태변수와 수문기상변량과의 상관성 분석)

  • Shim, Eunjeung;Uranchimeg, Sumiya;Lee, Yearin;Moon, Young-Il;Lee, Joo-Heon;Kwon, Hyun-Han
    • Journal of Korea Water Resources Association
    • /
    • v.54 no.12
    • /
    • pp.1295-1304
    • /
    • 2021
  • For the efficient use and management of water resources, a reliable rainfall-runoff analysis is necessary. Still, continuous hydrological data and rainfall-runoff data are insufficient to secure through measurements and models. In particular, as part of the reasonable improvement of a rainfall-runoff model in the case of an ungauged watershed, regionalization is being used to transfer the parameters necessary for the model application to the ungauged watershed. In this study, the GR4J model was selected, and the SCEM-UA method was used to optimize parameters. The rainfall-runoff model for the analysis of the correlation between watershed characteristics and parameters obtained through the model was regionalized by the Copula function, and rainfall-runoff analysis with the regionalized parameters was performed on the ungauged watershed. In the process, the intermediate state variables of the rainfall-runoff model were extracted, and the correlation analysis between water level and the ground water level was investigated. Furthermore, in the process of rainfall-runoff analysis, the Standardized State variable Drought Index (SSDI) was calculated by calculating and indexing the state variables of the GR4J model. and the calculated SSDI was compared with the standardized Precipitation index (SPI), and the hydrological suitability evaluation of the drought index was performed to confirm the possibility of drought monitoring and application in the ungauged watershed.

Development of daily spatio-temporal downscaling model with conditional Copula based bias-correction of GloSea5 monthly ensemble forecasts (조건부 Copula 함수 기반의 월단위 GloSea5 앙상블 예측정보 편의보정 기법과 연계한 일단위 시공간적 상세화 모델 개발)

  • Kim, Yong-Tak;Kim, Min Ji;Kwon, Hyun-Han
    • Journal of Korea Water Resources Association
    • /
    • v.54 no.12
    • /
    • pp.1317-1328
    • /
    • 2021
  • This study aims to provide a predictive model based on climate models for simulating continuous daily rainfall sequences by combining bias-correction and spatio-temporal downscaling approaches. For these purposes, this study proposes a combined modeling system by applying conditional Copula and Multisite Non-stationary Hidden Markov Model (MNHMM). The GloSea5 system releases the monthly rainfall prediction on the same day every week, however, there are noticeable differences in the updated prediction. It was confirmed that the monthly rainfall forecasts are effectively updated with the use of the Copula-based bias-correction approach. More specifically, the proposed bias-correction approach was validated for the period from 1991 to 2010 under the LOOCV scheme. Several rainfall statistics, such as rainfall amounts, consecutive rainfall frequency, consecutive zero rainfall frequency, and wet days, are well reproduced, which is expected to be highly effective as input data of the hydrological model. The difference in spatial coherence between the observed and simulated rainfall sequences over the entire weather stations was estimated in the range of -0.02~0.10, and the interdependence between rainfall stations in the watershed was effectively reproduced. Therefore, it is expected that the hydrological response of the watershed will be more realistically simulated when used as input data for the hydrological model.

Analysis of the Failure Mode in a Homogeneous Sandy Slope Using Model Test (모형실험을 이용한 균질한 사질토 사면의 붕괴형상 분석)

  • Song, Young-Suk;Park, Joon-Young;Kim, Kyeong-Su
    • The Journal of Engineering Geology
    • /
    • v.32 no.2
    • /
    • pp.209-219
    • /
    • 2022
  • To experimentally investigate the variation of soil characteristics in slope during rainfall and the shape of slope failure, the model test was performed using soil box and artificial rainfall simulator. The model test of slope formed by the homogenous sand was performed, and the saturation pattern in the model slope due to rainfall infiltration was observed. The slope model with the inclination of 35° was set up on the slope of 30°, and the rainfall intensity of 50 mm/hr was applied in the test. The soil depth of 35 cm was selected by considering the size of soil box, and the TDR (time domain reflectometry) sensors were installed at various depths to investigate the change of soil characteristics with time. As the result of model test, the slope model during rainfall was saturated from the soil surface to the subsurface, and from the toe part to the crest part due to rainfall infiltration. That is, the toe part of slope was firstly saturated by rainfall infiltration, and then due to continuous rainfall the saturation range was enlarged from the toe part to the crest part in the slope model. The failure of slope model was started at the toe part of slope and then enlarged to the crest part, which is called as the retrogressive failure. At the end of slope failure, the collapsed area increased rapidly. Also, the mode of slope failure was rotational. Meanwhile, the slope failure was occurred when the matric suction in the slope was reached to the air entry value (AEV) estimated in soil-water characteristic curve (SWCC).

A Programming of Hydrologic Analysis Procedure for the Probable Isohyetal Chart in Korea (한국 확률강우량도 작성을 위한 수문해석방법 개발)

  • 이원환
    • Water for future
    • /
    • v.20 no.2
    • /
    • pp.139-150
    • /
    • 1987
  • The present study is to develop the hydrologic analysis procedure for the purpose of drawing the probable isohyetal charts in Korea. In the establishment of optimal distribution types, the eleven continuous probability distribution types included the transformed variable normal distribution (Y-k method) is applied to the annual maximum rainfall depth series in each duration. The optimal selection of distribution is done by Chi-square test and Kolmogorov-Smirnov test in the eui-class interval. The application of probability distribution is checked by the fitting on four durations of annual maximum rainfall data(10 min., 60 min., 6 hrs., and 24hrs.) at four meteorological stations in Korea (Seoul, In Cheon, Bu san, and Kwang Ju). The properties in hydrologic application of the considered distribution and the hydrologic characteristics of the applied rainfall data groups are investigated from the results of this study.

  • PDF

Climate change effect on storm drainage networks by storm water management model

  • Hassan, Waqed Hammed;Nile, Basim Khalil;Al-Masody, Batul Abdullah
    • Environmental Engineering Research
    • /
    • v.22 no.4
    • /
    • pp.393-400
    • /
    • 2017
  • One of the big problems facing municipalities is the management and control of urban flooding where urban drainage systems are under growing pressure due to increases in urbanization, population and changes in the climate. Urban flooding causes environmental and infrastructure damage, especially to roads, this damage increasing maintenance costs. The aim of the present study is to develop a decision support tool to identify the performance of storm networks to address future risks associated with climate change in the Middle East region and specifically, illegal sewer connections in the storm networks of Karbala city, Iraq. The storm water management model has been used to simulate Karbala's storm drainage network using continuous hourly rainfall intensity data from 2008 to 2016. The results indicate that the system is sufficient as designed before consideration of extra sewage due to an illegal sewer connection. Due to climate changes in recent years, rainfall intensity has increased reaching 33.54 mm/h, this change led to flooding in 47% of manholes. Illegal sewage will increase flooding in the storm system at this rainfall intensity from between 39% to 52%.

A Trace of Landcover Change in a Landslide Vulnerable Area (산사태 취약지에서의 토지피복상태 변화 추적)

  • Yang, In-Tae;Chun, Ki-Sun;Park, Jae-Kook;Lee, Sang-Yun
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
    • /
    • 2007.04a
    • /
    • pp.375-378
    • /
    • 2007
  • Kangwondo area is mountainous and landslide happens easily during the rainy period in summer time. Especially, when there is torrential downpour caused by the unusual weather change, there will be greater possibility to see landslide. Another reason behind landslide is the continuous forest fire in these several years. Since the surface of the earth has been changed by the fire, when rainfall comes, landslide just happens easily. Also, it is reported that landcover condition, excepted rainfall condition, is the most effect for determining landslide susceptibility area. In this study, it is determined a landslide vulnerable area and landcover information is extracted from four satellite image(Landsat TM), about the landslide vulnerable area, which is pictured for each year. And which distribution change is analyzed.

  • PDF

Bund Collapse in Sloping Paddy Area by a Heavy Rainfall -Case Study for Dongrim-ri in Chungbuk Province- (집중호우에 의한 경사지논의 논둑붕괴 -충북 청원군 옥산면 동림리의 사례-)

  • 김진수
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.38 no.5
    • /
    • pp.55-63
    • /
    • 1996
  • The situation and cause of bund collapse in steep sloping paddy area by a heavy rainfall of Chungbuk Province were investigated by field surveys. Shapes of paddy plots are irregular and average size of them is 12.6a. Surface, groundwater and plot-to-plot irrigations are being carried out in the study plots. The type of bund collapse can be divided as follows: overflow type and inundation type. The overflow type generally occurs at the bund with slope lacking the design standard. The inundation type damages paddy plots more seriously than the overflow type. It induces continuous bund collapse from a inflow-plot to a outflow-plot and includes lots of type (inside paddy) collapse, which results in much subsoil erosion. The installation of mountain stream weir and maintenance of mountain stream are proposed to prevent the inundation type collapse.

  • PDF

Combining Four Elements of Precipitation Loss in a Watershed (유역내 네가지 강수손실 성분들의 합성)

  • Yoo, Ju-Hwan
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2012.05a
    • /
    • pp.200-204
    • /
    • 2012
  • In engineering hydrology, an estimation of precipitation loss is one of the most important issues for successful modeling to forecast flooding or evaluate water resources for both surface and subsurface flows in a watershed. An accurate estimation of precipitation loss is required for successful implementation of rainfall-runoff models. Precipitation loss or hydrological abstraction may be defined as the portion of the precipitation that does not contribute to the direct runoff. It may consist of several loss elements or abstractions of precipitation such as infiltration, depression storage, evaporation or evapotranspiration, and interception. A composite loss rate model that combines four loss rates over time is derived as a lumped form of a continuous time function for a storm event. The composite loss rate model developed is an exponential model similar to Horton's infiltration model, but its parameters have different meanings. In this model, the initial loss rate is related to antecedent precipitation amounts prior to a storm event, and the decay factor of the loss rate is a composite decay of four losses.

  • PDF

Development of Daily Rainfall Simulation Model Using Piecewise Kernel-Pareto Continuous Distribution (불연속 Kernel-Pareto 분포를 이용한 일강수량 모의 기법 개발)

  • Kwon, Hyun-Han;So, Byung Jin
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.31 no.3B
    • /
    • pp.277-284
    • /
    • 2011
  • The limitations of existing Markov chain model for reproducing extreme rainfalls are a known problem, and the problems have increased the uncertainties in establishing water resources plans. Especially, it is very difficult to secure reliability of water resources structures because the design rainfall through the existing Markov chain model are significantly underestimated. In this regard, aims of this study were to develop a new daily rainfall simulation model which is able to reproduce both mean and high order moments such as variance and skewness using a piecewise Kernel-Pareto distribution. The proposed methods were applied to summer and fall season rainfall at three stations in Han river watershed in Korea. The proposed Kernel-Pareto distribution based Markov chain model has been shown to perform well at reproducing most of statistics such as mean, standard deviation and skewness while the existing Gamma distribution based Markov chain model generally fails to reproduce high order moments. It was also confirmed that the proposed model can more effectively reproduce low order moments such as mean and median as well as underlying distribution of daily rainfall series by modeling extreme rainfall separately.