• 제목/요약/키워드: Evapotranspiration index

검색결과 156건 처리시간 0.028초

기후학적 물수지에 의한 금강유역의 습윤/건조 상태 분석 (Analysis of Wetness/Dryness in Geum River Basin based on Climatic Water Balance)

  • 김주철;이상진
    • 한국물환경학회지
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    • 제26권2호
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    • pp.243-251
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    • 2010
  • Evapotranspiration and rainfall-runoff are the major components of hydrological cycle and thereby the changes of them can directly affect the wetness/dryness or runoff characteristics of basins. In this study the wetness/dryness in Geum river basin are classified by dint of cumulative probability density function of monthly moisture index and the long term changes of them are analyzed based on climatic water balance concept. The drought events in Geum river basin are selected through evaluation of monthly moisture index and the various hydrological properties of them are investigated in detail. Also the trends of time-series of climatic water balance components are examined by Seasonal Kendall test and the variability of hydrological cycle in Geum river basin during the recent decade is inquired. It is judged that the results of this study can be contributed to establishment of the counter plan against the future drought events as the fundamental information.

밭작물 소비수량에 관한 기초적 연구(III)-고추 및 가을 무우- (Basic Studies on the Consumptive Use of Water Required for Dry Field Crops (3) -Red Pepper and Radish-)

  • 김철기;김진한;정하우;최홍규;권영현
    • 한국농공학회지
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    • 제32권1호
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    • pp.55-71
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    • 1990
  • The purpose of this study is to find out the basic data for irrigation plans of red pepper and radish during the growing period, such as total amount of evapotranspiration, coefficent of evapotranspiration at each growth stage, the peak stage of evapotranspiration, the maximum ten day evapotranspiration , optimum irrigation point, total readily available moisture and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation point with pH1.7-2.0, pF2.1-2.4 and pF2.5-2.8, at soil texture of sandy soil, sandy loam and silty clay for both red pepper and radish, with two replications. The results obtained are summarized as follows. 1.1/10 exceedance probability values of maximum total pan evaporation during growing period for red peppr and radish were shown as 663.6 mm and 251.8 mm. respectively, and those of maximum ten day pan evaporation for red pepper and radish, 67.1 mm and 46.9 mm, respectively. 2.The time that annual maximum of ten day pan evaporation can he occurred, exists at any stage between the middle of May and the late of August for red pepper, and at any stage between the late of August and the late September for radish. 3.The magnitude of evapotranspiration and its coefficient for red pepper was occurred large in order of pF1.7-2.0 pF2.1-2.4 and pF2.5~2.8 in aspect of irrigation point and the difference in the magnitude of evapotranspiration and of its coefficient between levels of irrigation point was difficult to be found out due to the relative increase in water consumption resulted from large flourishing growth at the irrigation point in lower water content for radish. In aspect of soil texture they were appeared large in order of sandy loam, silty clay and sandy soil for both red pepper and radish. 4.The magnitude of leaf area index was shown large in order of pF2.1-2.4, pF2.5-2.8, and pFl.7-2.0, for red pepper and of pF2.5-2.8, pF2.1-2.4, pFl.7-2.0 for radish in aspect of irrigation point, and large in order of sandy loam, silty clay, sandy soil for both red pepper and radish in aspect of soil texture 5.1/10 exceedance probability value of evapotranspiration and its coefficient during the growing period for red pepper were shown as 683.5 mm and 1.03, respectively, while those of radish, 250.3 mm and 0, 99. respectively. 6.The time that the maximum evapotranspiration of red pepper can be occurred is in the middle of August around the date of ninetieth to hundredth after transplanting, and the time for radish is presumed to be in the late of September, around the date of thirtieth to fourtieth after sowing. At that time, 1/10 exceedance probability value of ten day evapotranspiration and its coefficient for red pepper is assumed to be 81.8 mm and 1.22, respectively, while those of radish, 49, 7 mm and 1, 06, respectively. 7.Optimum irrigation point for red pepper on the basis of the yield of raw matter is assumed to be pFl.7-2.0 for sandy soil, pF2.5-2.8 for sandy loam, and pF2.1-2.4 for silty clay. while that for radish is appeared to be pF2.5-2.8 in any soil texture used. 8.The soil moisture extraction patterns of red pepper and radish have shown that maximum extraction rates exist at 7 cm deep layer at the beginning stage of growth in any soil texture and that extraction rates of 21 cm to 35 cm deep layer are increased as getting closer to the late stage of growth. And especially the extraction rates have shown tendency to be greatest at 21cm deep layer from the most flourishing stage of growth for red pepper and at the last stage of growth for radish. 9.The total readily available moisture on the basic of the optimum irrigation point become 3.77-8.66 mm for sandy soil, 28.39-34.67 mm for sandy loam and 18.40-25.70 mm for silty clay for red pepper of each soil texture used but that of radish that has shown the optimum irrigation point of pF2.5-2.8 in any soil texture used. 12.49-15.27 mm for sandy soil, 23.03-28.13 mm for sandy loam, and 22.56~27.57 mm for silty clay. 10.On the basis of each optimum irrigation point. the intervals of irrigation date at the growth stage of maximum consumptive use of red pepper become l.4 days for sandy soil, 3.8 days for sandy loam and 2.6 days for silty clay, while those of radish, about 7.2 days.

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산림식생에 따른 유역 물수지 영향 평가 (Assessment of Forest Vegetation Effect on Water Balance in a Watershed)

  • 김철겸;김남원
    • 한국수자원학회논문집
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    • 제37권9호
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    • pp.737-744
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    • 2004
  • 본 연구에서는 산림식생에 따른 장기적인 측면에서의 유역 물수지 영향을 살펴보기 위하여 보청천 유역을 대상유역으로 선정하고, 준분포형 매개변수 모형인 SWAT 모형을 적용하여, 침엽수와 활엽수에 따른 증발산, 지표유출, 중간유출, 기저유출, 총 유출의 차이를 검토하였다. 먼저 SWAT 모형내 식생 생장 알고리즘을 수정하여 연중 일정한 엽면적지수를 갖는 국내 침엽수림의 생장 특성을 반영할 수 있도록 하였으며, 대상유역을 하나의 토지피복을 갖는 가상의 유역으로 설정한 후, 수정된 SWAT 모형을 적용하여 각 물수지 요소 변화를 모의한 결과, 침엽수가 활엽수에 비해 증발산 증가 및 유출 감소에 더 영향을 미치는 것으로 나타났다. 그러나, 보다 정량적인 규명과 유출모형의 불확실성을 보완하기 위해서는 수종 외에 수령, 식재밀도, 식재위치, 토양특성자료 등 다양한 조건이 충분히 고려되어야 할 것이다.

수문기상가뭄지수 (HCDI) 개발 및 가뭄 예측 효율성 평가 (Development of Hydroclimate Drought Index (HCDI) and Evaluation of Drought Prediction in South Korea)

  • 류재현;김정진;이경도
    • 한국농공학회논문집
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    • 제61권1호
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    • pp.31-44
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    • 2019
  • The main objective of this research is to develop a hydroclimate drought index (HCDI) using the gridded climate data inputs in a Variable Infiltration Capacity (VIC) modeling platform. Typical drought indices, including, Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and Self-calibrated Palmer Drought Severity Index (SC-PDSI) in South Korea are also used and compared. Inverse Distance Weighting (IDW) method is applied to create the gridded climate data from 56 ground weather stations using topographic information between weather stations and the respective grid cell ($12km{\times}12km$). R statistical software packages are used to visualize HCDI in Google Earth. Skill score (SS) are computed to evaluate the drought predictability based on water information derived from the observed reservoir storage and the ground weather stations. The study indicates that the proposed HCDI with the gridded climate data input is promising in the sense that it can help us to predict potential drought extents and to mitigate its impacts in a changing climate. The longer term drought prediction (e.g., 9 and 12 month) capability, in particular, shows higher SS so that it can be used for climate-driven future droughts.

Signal of vegetation variability found in regional-scale evapotranspiration as revealed by NDVI and assimilated atmospheric data in Asia

  • Suzuki, Rikie;Masuda, Kooiti;Yasunari, Tetsuzo;Yatagai, Akiyo
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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    • pp.685-689
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    • 2002
  • This study focused the relationship between the Normalized Difference Vegetation Index (NDVI) and the evapotranspiration (ET) temporal changes. Especially, the interannual change of the NDVI and ET from 1982 to 2000 at regional to continental scales was highlighted mainly over Asia. Monthly global NDVI data were acquired from Pathfinder AVHRR Land (PAL) data (1$\times$1 degree resolution). The monthly ET was estimated from assimilated atmospheric data provided from National Centers for Environmental Prediction (NCEP) (2.5$\times$2.5 degree resolution), and gridded global precipitation data of CPC Merged Analysis of Precipitation (CMAP) (2.5$\times$2.5 degree resolution). Significant positive correlations were found between the NDVI and ET interannual changes in May and June over western Siberia. Moreover, it was revealed that the most of area in Asia has positive correlation coefficient in May and June. These results delineate that the vegetation activity significantly contributes to the ET interannual change over extensive areas.

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Intercomparison of interannual changes in NDVI from PAL and GIMMS in relation to evapotranspiration over northern Asia

  • Suzuki Rikie;Masuda Kooiti;Dye Dennis
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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    • pp.162-165
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    • 2004
  • The authors' previous study found an interannual covariability between actual evapotranspiration (ET) and the Normalized Difference Vegetation Index (NDVI) over northern Asia. This result suggested that vegetation controls interannual variation in ET. In this prior study, NDVI data from the Pathfinder AVHRR Land (PAL) dataset were analyzed. However, studies of NDVI interannual change are subject to uncertainty, because NDVI data often contain errors associated with sensor- and atmosphere-related effects. This study is aimed toward reducing this uncertainty by employing NDVI dataset, from the Global Inventory Monitoring and Modeling Studies (GIMMS) group, in addition to PAL. The analysis was carried out for the northern Asia region from 1982 to 2000. 19-year interannual change in PAL-NDVI and GIMMS-NDVI were both compared with interannual change in model-assimilated ET. Although the correlation coefficient between GIMMS-NDVI and ET is slightly less than for PAL-NDVI and ET, for both NDVI datasets the annual maximum correlation with ET occurs in June, which is near the central period of the growing season. A significant positive correlation between GIMMS-NDVI and ET was observed over most of the vegetated land area in June as well as PAL-NDVI and ET. These results reinforce the authors' prior research that indicates the control of interannual change in ET is dominated by interannual change in vegetation activity.

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Airborne Remote Sensing of Evapotranspiration over Rice Paddy

  • Chen, Y.Y.;Liou, Yuei-An
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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    • pp.351-353
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    • 2003
  • We present a retrieval scheme for the remote sensing of evapotranspiration (ET) over rice paddy. To perform the retrieval, high-resolution airborne imagery of multi-spectral visible and thermal infrared data, and ground-based meteorological measurements are utilized. Our ET retrieval scheme is based on the basic principal of surface energy budget, which is a result of balance in longwave and shortwave radiation, latent heat, sensible heat, and energy flux into the ground. To partition the latent and sensible heat fluxes of interest from the energy balance equation, three basic parameters are of most concern, including albedo, surface temperature, and normalized difference vegetation index (NDVI). The NDVI and albedo can be easily derived from the visible and near infrared spectral data, while the surface tem-perature can be determined through the analysis of the infrared data with the Stefan Boltzmann law. From the airborne imagery taken on 28 April 2003, we observe very good dry and wet pixels that can be easily corre-sponded to the radiation and evaporation controlled crite-ria, respectively, and, hence, for the further use in defin-ing the evaporative fraction needed to partition sensible and latent heat fluxes from the net energy flux. The de-rived ET is compared with the in situ measurements.

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AMSR2 위성영상 기반 토양수분을 이용한 우리나라 월별 FDSI 산정 및 공간 분포 특성 분석 (Estimation and Spatial Distribution of Monthly FDSI Using AMSR2 Satellite Image-based Soil Moisture in South Korea)

  • 천범석;이태화;정광준;신용철
    • 한국농공학회논문집
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    • 제64권4호
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    • pp.31-43
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    • 2022
  • In this study, we estimated the monthly FDSI (Flash Drought Stress Index) for assessing flash drought on South Korea using AMSR2(Advanced Microwave Scanning Radiometer 2) satellite-based soil moisture footprints. We collected the AMSR2 soil moisture and climate-land surface data from April to November 2018 for analyzing the monthly FDSI values. We confirmed that the FDSI values were high at the regions with the high temperature/evapotranspiration while the precipitation is relatively low. Especially, the regions which satisfied an onset of flash drought (FDSI≧0.71) were increased from June. Then, the most of regions suffered by flash drought during the periods (July to August) with the high temperature and evapotranspiration. Additionally, the impacts of landuse and slope degree were evaluated on the monthly FDSI changes. The forest regions that have the steep slope degree showed the relatively higher FDSI values than the others. Thus, our results indicated that the the slope degree has the relatively higher impact on the onset and increasing of flash drought compared to the others.

Influence of climate change on crop water requirements to improve water management and maize crop productivity

  • Adeola, Adeyemi Khalid;Adelodun, Bashir;Odey, Golden;Choi, Kyung Sook
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2022년도 학술발표회
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    • pp.126-126
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    • 2022
  • Climate change has continued to impact meteorological factors like rainfall in many countries including Nigeria. Thus, altering the rainfall patterns which subsequently affect the crop yield. Maize is an important cereal grown in northern Nigeria, along with sorghum, rice, and millet. Due to the challenge of water scarcity during the dry season, it has become critical to design appropriate strategies for planning, developing, and management of the limited available water resources to increase the maize yield. This study, therefore, determines the quantity of water required to produce maize from planting to harvesting and the impact of drought on maize during different growth stages in the region. Rainfall data from six rain gauge stations for a period of 36 years (1979-2014) was considered for the analysis. The standardized precipitation and evapotranspiration index (SPEI) is used to evaluate the severity of drought. Using the CROPWAT model, the evapotranspiration was calculated using the Penman-Monteith method, while the crop water requirements (CWRs) and irrigation scheduling for the maize crop was also determined. Irrigation was considered for 100% of critical soil moisture loss. At different phases of maize crop growth, the model predicted daily and monthly crop water requirements. The crop water requirement was found to be 319.0 mm and the irrigation requirement was 15.5 mm. The CROPWAT 8.0 model adequately estimated the yield reduction caused by water stress and climatic impacts, which makes this model appropriate for determining the crop water requirements, irrigation planning, and management.

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MODIS 영상을 활용한 한반도의 시공간적 물 이용효율 변동 및 가뭄과의 연관성 분석 (Spatial and Temporal Variations in the Water Use Efficiency and its Drought Signal on the Korean Peninsula using MODIS-derived Products)

  • 김정빈;호현주;엄명진;김연주
    • 대한원격탐사학회지
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    • 제34권3호
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    • pp.553-564
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    • 2018
  • 최근 대두되고 있는 기후변화는 물과 탄소의 순환으로 이뤄진 생태계 간의 상호작용으로 인해 발생한다. 이를 분석하기 위해 물 이용효율(Water Use Efficiency, WUE)이 사용되는데, 이는 광합성 시 사용되는 수분 대비 흡수되는 탄소의 비율이다. 물 이용효율은 주변 환경의 기상 및 지표 조건에 영향을 받으며, 생태계의 변화를 반영하는 지표다. 본 연구에서는 한반도의 시공간적 물 이용효율을 분석하며, 나아가 가뭄과의 연관성을 가뭄 지수를 통해 보고자 한다. 물 이용효율과 가뭄 지수를 측정하기 위해서 Moderate Resolution Imaging Spectroradiometer(MODIS) 영상으로부터 Gross Primary Production(GPP, 총일차생산량)과 Evapotranspiration(ET, 증발산량) 자료를 산정하였다. 이를 통해 계산한 물 이용효율은 한반도의 전 지역과 모든 식생 종류에 대해 여름 우기철에 감소하는 것으로 밝혀졌다. 나아가 연간 물 이용효율은 가뭄 지수와 음의 상관관계를 보이며 한반도의 남쪽 지역으로 갈수록 그 상관계수가 증가하였다.