• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.424-424
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• 2017

Several studies of the world have analyzed the regional rainfall trends in large data sets. However, it reported that the long-term behavior of rainfall was different on spatial and temporal scales. The objective of this study is to determine the local trends of rainfall indices in the Yom River Basin, Thailand. The rainfall indices consist of the annual total precipitation (PRCTPOP), number of heavy rainfall days ($R_{10}$), number of very heavy rainfall days ($R_{20}$), consecutive of dry days (CDD), consecutive of wet days (CWD), daily maximum rainfall ($R_{x1}$), five-days maximum rainfall ($R_{x5}$), and total of annual rainy day ($R_{annual}$). The rainfall data from twelve hydrological stations during the period 1965-2015 were used to analysis rainfall trend. The Mann-Kendall test, which is non-parametric test was adopted to detect trend at 95 percent confident level. The results of these data were found that there is only one station an increasing significantly trend in PRCTPOP index. CWD, which the index is expresses longest annual wet days, was exhibited significant negative trend in three locations. Meanwhile, the significant positive trend of CDD that represents longest annual dry spell was exhibited four locations. Three out of thirteen stations had significant decreasing trend in $R_{annual}$ index. In contrast, there is a station statistically significant increasing trend. The analysis of $R_{x1}$ was showed a station significant decreasing trend at located in the middle of basin, while the $R_{x5}$ of the most locations an insignificant decreasing trend. The heavy rainfall index indicated significant decreasing trend in two rainfall stations, whereas was not notice the increase or decrease trends in very heavy rainfall index. The results of this study suggest that the trend signal in the Yom River Basin in the half twentieth century showed the decreasing tendency in both of intensity and frequency of rainfall.

• 해양환경안전학회지
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• 제26권3호
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• pp.233-241
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• 2020

We examined long-term variations in sea surface temperature (SST) and annual amplitudes of SST around the Korean Peninsula. Two SST data sets with data periods of approximately 51 years and longer than 100 years, respectively, were obtained from the National Institute of Fisheries Science and Japan Meteorological Agency. SST of Korean waters clearly increased during last 51 years (1968-2018), which was 2.5 times higher than the global trend. This significant increasing trend was caused by the dominant increasing SST trend during winter. However, a negative and positive SST anomaly frequently appeared during winter and summer, respectively, in a recent decade. These features of seasonal SST variation have changed the annual amplitude of SST, and resulted in a drastically increasing trend after 2009. Using the longer SST data set, it was revealed that the decreasing SST trend in winter began in the 2000s and the increasing SST trend in summer bagan in the 1990s. During a recent decade, there was a distinctive SST increase in summer, whereas a clear decrease in winter. In summary, the annual amplitude of SST around the Korean Peninsula significantly changed from a decreasing trend to an increasing trend during a recent decade.

• 한국수자원학회논문집
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• 제43권4호
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• pp.409-419
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• 2010

본 연구에서는 국내 기상관측소 중 관측년수가 30년 이상인 관측소 63개 지점을 대상으로 9개의 수문기상수문인자 즉, 연강수량, 연강수일수, 연평균기온, 연평균상대습도, 연일조시간, 연증발량, 연강수계속시간, 연적설일수, 연신적설일수 자료를 각 지점별로 수집하고, 수문기상인자에 대한 기본통계량, 선형회귀분석, 이동평균법을 통해 수문기상인자의 기본적인 특성을 알아보았다. 또한 통계학적기법인 Hotelling-Pabst 검정과 Mann-Kendall 검정을 통해 경향성을 분석하였다. 기본통계량 분석결과 우리나라의 기후특성상 여름철에 강우가 집중되며, 계절별 강수량의 편차가 큰 전형적인 특성을 확인할 수 있었다. 선형회귀 분석과 5년 이동평균법을 통해서는 시간이 경과함에 따라 연강수량과 연평균기온은 증가, 연평균상대습도와 연일조시간은 감소, 연강수일수는 지점별로 증가 또는 감소하는 추세를 보였다. Hotelling-Pabst 검정과 Mann-Kendall 검정을 통한 경향성분석에서는 연평균상대습도, 연평균기온에서 공통적으로 경향성이 나타났으며, 연강수량, 연강수일수, 연일조시간은 지역에 따라 상이한 결과를 보였다.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.658-659
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• 2015

GCM and scenario uncertainties are first investigated for 5 major watersheds (Han River, Paldang dam, Namhan River, Bukhan River and Imjin River watersheds). As a result of this study, it is found that CCSM3-based annual precipitation increases linearly with respect to the 10-year moving average values while CSIRO-based precipitation does not show much of trend. The results from annual DJF mean precipitation show a similar trend with respect to their 10-year moving average values. Both CCSM3- and CSIRO-based annual JJA mean precipitation do not show much of trend toward 21^st century. In general, CCSM3-based precipitation values are slightly higher than CSIRO-based values with respect to their annual and annual JJA mean precipitation values, but CSIRO-based annual DJF mean precipitation values are slightly higher than CCSM3-based values. In case of mean air temperature between CCSM3 and CSIRO during 21^st century, all of results show a clear trend in warming with the passage of time for 5 watersheds. However the upward trends from CCSM3-based values slow down toward end of 21^stcentury while CSRIO-based values increases almost linearly.

• 대한토목학회논문집
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• 제30권3B호
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• pp.243-255
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• 2010

본 연구에서는 pan 증발량 분포와 추세를 분석하였다. 이를 위하여 전국 56개 기후관측지점에서 1973년부터 1990년까지 의 pan 증발량 자료를 수집하여 분석을 실시하였다. 분석을 위하여 계절적 영향을 고려하여 1월, 4월, 7월 그리고 10월의 월평균 일별과 연평균 일별 pan 증발량 추세를 분석하였다. 연구결과 연평균 일별 pan 증발량은 56개 연구지역 중에서 38개 연구지역에서 감소추세를 보이고 있고, 1월 평균 일별 pan 증발량의 경우 33개 연구지역에서 pan 증발량 감소추세를 보이고 있다. 4월의 경우 38개 지역에서 증가추세를 보이고, 7월의 경우 47개 지역에서 감소추세를 보여서, 전반적으로 감소추세를 보이고 있다. 10월의 경우 35개 지역에서 증가추세를 보여서 전반적으로 증가추세를 보이고 있다. 따라서 전반적으로 연별과 1월, 7월은 pan 증발량이 감소추세를 보이고, 4월과 10월은 증가추세를 보이고 있다. 또한 인근에 위치한 권역별로도 다른 추세를 보이는 것으로 나타나서 지리지형적 요인이 pan 증발량 추세에 영향을 미치는 것으로 판단된다. 11개 기후관측지점에서 1973년부터 2006년까지의 pan 증발량 자료와 기후요소자료를 수집하여 추세분석을 실시한 결과, 기온, 상대습도 그리고 풍속추세는 연별이나 월별 pan 증발량 추세와 서로 같거나 또는 상이한 경향을 보이나, 일사량 추세는 연 및 월별 모두에서 pan 증발량 추세와 동일한 경향을 보이고, 강수량 추세는 연 및 월별 모두에서 pan 증발량 추세와 상반된 경향을 보였다.

• 한국해안·해양공학회논문집
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• 제28권2호
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• pp.109-115
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• 2016

우리나라 동해안 6개 관측점에서 장기간 관측된 파랑자료를 이용하여 폭풍파의 출현 추세를 검토하였다. 한국해양과학기술원의 4개 정점(속초, 묵호, 후포, 진하)에서는 관측기간 동안 유의파고의 연별 평균값과 최대값의 주목할 만한 추세가 나타나지 않았다. 또한, 폭풍파의 연별 출현 횟수는 진하에서만 완만한 증가 추세가 나타났고 나머지 세 정점에서는 감소 추세를 보였다. 그러나 기상청 동해부이의 경우 유의파고의 연별 평균값과 최대값 및 폭풍파 연별 출현횟수가 2009년 이후로 매우 급격하게 증가하는 경향이 나타났으며 해당 자료의 연속성이 확보되지 않은 것으로 확인되었다.

• 한국수산과학회지
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• 제3권1호
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• pp.45-51
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• 1970

1926년~1967년의 42년간의 년간 총어획고를 자료로 하여 Periodogram 분석 방법에 의한 어황 보간과 어황 예측을 한 결과 다음을 얻었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.27-27
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• 2023

To analyze the evolution of water resources in Qiandao Lake Basin under the condition of climate change, a WEP-L distributed hydrological model was established to simulate the water cycle process in the basin during 1960-2020. The Mann-Kendall non-parametric test method and Hurst index method were used to analyze the inter-annual variation and annual distribution characteristics of the total water resources in the basin. The multi-scale temporal and spatial distribution and evolution trend of water resources in Qiandao Lake Basin were evaluated. The results show that: (1) The WEP-L model has good simulation results in the Qiandao Lake basin, and the Nash coefficient rate is above 0.83 in the periodic period and above 0.85 in the verification period. (2) The water yield coefficient of the whole basin ranges from 0.436 to 0.630. The annual average total water resource is 12.25 billion m³, equivalent to 1176.4mm of water depth. The annual distribution process shows a unimodal structure, and the water depth of each sub-basin ranges from 742 mm to 1266 mm, and the spatial distribution is higher in the west and lower in the east. (3) The annual water resources series in the basin showed an insignificant upward trend, and the Hurst index was 0.86, indicating a continuous upward trend. From the perspective of monthly water resources, January and February increased significantly, the other months were not significant changes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.581-585
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• 2010

This study introduced a Bayesian based frequency analysis in which the statistical trend seasonal analysis for hydrologic extreme series is incorporated. The proposed model employed Gumbel and GEV extreme distribution to characterize extreme events and a fully coupled bayesian frequency model was finally utilized to estimate design rainfalls in Seoul. Posterior distributions of the model parameters in both trend and seasonal analysis were updated through Markov Chain Monte Carlo Simulation mainly utilizing Gibbs sampler. This study proposed a way to make use of nonstationary frequency model for dynamic risk analysis, and showed an increase of hydrologic risk with time varying probability density functions. In addition, full annual cycle of the design rainfall through seasonal model could be applied to annual control such as dam operation, flood control, irrigation water management, and so on. The proposed study showed advantage in assessing statistical significance of parameters associated with trend analysis through statistical inference utilizing derived posterior distributions.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.193-193
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• 2017

Trend analysis can enhance our knowledge of the dominant processes in the area and contribute to the analysis of future climate projections. The results of previous studies in South Korea showed that southeast regions of Korea had the highest value of evapotranspiration. Thereby, it is of interest to determine the trend analysis in hydrological variables in this area. In this study, the recent 35 year trends of precipitation, reference evapotranspiration, and aridity index in monthly and annual time scale will be analyzed over three stations (Pohang, Daegu, and Pusan) of southeast Korea. After removing the significant Lag-1 serial correlation effect by pre-whitening, non-parametric statistical Mann-Kendall test was used to detect the trends. Also, the slope of trend of the Mann-Kendall test was determined by using Theil-Sen's estimator. The results of the trend analysis of reference evapotranspiration on the annual scale showed the increasing trend for the three mentioned stations, with significant increasing trend for Pusan station. The results obtained from this research can guide development if water management practices and cropping systems in the area that rely on this weather stations. The approaches use and the models fitted in this study can serve as a demonstration of how a time series trend can be analyzed.