• 한국농공학회지
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• 제30권3호
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• pp.51-57
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• 1988

The purpose of this paper is to know the effect of Adjustment factor (C) in Penman equation In the modified Penman equation by Doorenbos and Pruitt (1977), Potential Evapotranspiration(PET) was calculated in cases of (1) neglecting Adjustment factor (C=1, 0, A), (2) fixing Day/Night wind ratio (URATIO) to 2.0(B-l) and computing daily URATIO (B-2), and was compared with Actual Evapotranspiration (AET) for paddy fields in Suwon (1985-1986). The followings are a summary of this study results ; 1. Using 1985-1986 meteorological data, daily average PET in cases of A, B-i, B-2 were 4.61 mm/day, 4.81 mm/day and 5.36 mm/day respectively and daily average AET was 4.26 mm/day. The increment ratios of PET based on case A were 100%, 104.34% and 116.27% 2. The range of Adjustment factor (C) in cases of B-i, B-2 were 0.916-1.140 and 0.922-1.392 respectively. 3. The regression coefficient(r) between AET and PET in cases of A, B-i, B-2 were 0.928, 0.924 and 0.915 respectively.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.641-646
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• 2009

This study examines the effects of water shortage on agricultural wages in Northwest Bangladesh. For this study, meteorological data including information on the monthly temperature, precipitation, wind speed, hour of sunshine and humidity of six weather stations have been utilized during the monitoring period from 1985 to 2005. With the objective to analyze water surplus and water deficiency, a simple soil-water balance model and the modified Penman formula were applied to the Northwest Bangladesh. The seasonality of Mann-Kendell trend statistics has been used to identify the spatial variation of water surplus and deficiency throughout the region. For micro level verification of the result, a detailed field survey has been conducted within the study area. The results showed that the values of the potential evapotranspiration estimated by the modified Penmen equation were negative for certain periods. In this instance, the water deficiency of the district of Rajshahi was observed significantly in the period of pre-monsoon and post-monsoon. The field study also verified that because of such deficiency in water, the agricultural scenario of the area was widely influenced which lead to less agricultural production and less economic benefits.

• 한국농공학회논문집
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• 제49권3호
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• pp.11-20
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• 2007

Estimation of crop consumptive use is a key term of agricultural water resource systems design and operation. The 10-year return period drought has special aspects as a reference period in design process of irrigation systems in terms of agricultural water demand analysis so that crop evapotranspiration (ETc) about the return period also has to be analyzed to assist understanding of crop water requirement of paddy rice. In this study, The ETc of 10-year return period drought was computed using frequency analysis by 54 meteorological stations. To find an optimal probability distribution, 8 types of probability distribution function were tested by three the goodness of fit tests including ${\chi}^2$(Chi-Square), K-S (Kolmogorov-Smirnov) and PPCC (Probability Plot Correlation Coefficient). Optimal probability distribution function was selected the 2-parameter Log-Normal (LN2) distribution function among 8 distribution functions. Using the two selected distribution functions, the ETc of 10-year return period drought was estimated for 54 meteorological stations and compared with prior study results suggested by other researchers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권10호
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• pp.3275-3298
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• 2022

Cloud-based architectures for precision agriculture are domain-specific controlled and require remote access to process and analyze the collected data over third-party cloud computing platforms. Due to the dynamic changes in agricultural parameters and restrictions in terms of accessing cloud platforms, developing a locally controlled and real-time configured architecture is crucial for efficient water irrigation and farmers management in agricultural fields. Thus, we present a new implementation of an independent sensor-enabled architecture using variety of wireless-based sensors to capture soil moisture level, amount of supplied water, and compute the reference evapotranspiration (ETo). Both parameters of soil moisture content and ETo values was then used to manage the amount of irrigated water in a small-scale agriculture field for 356 days. We collected around 34,200 experimental data samples to evaluate the performance of the architecture under different agriculture parameters and conditions, which have significant influence on realizing real-time monitoring of agricultural fields. In a proof of concept, we provide empirical results that show that our architecture performs favorably against the cloud-based architecture, as evaluated on collected experimental data through different statistical performance models. Experimental results demonstrate that the architecture has potential practical application in a many of farming activities, including water irrigation management and agricultural condition control.

• 한국토양비료학회지
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• 제43권6호
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• pp.812-822
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• 2010

1. 우리나라 전국을 45개 지역으로 구분하여 최근 30년간의 기상자료 분석에 의한 5월~6월의 일평균 PET는 2.99 mm $day^{-1}$ 이었다. 2. 토성별 유효토양수분보유량 (AWS)은 사양토 16.0%~미사질양토 24.7% 범위이었다. 3. 봄배추의 45개 지역별, 3개 토성 및 5개 순별, 총 675경우의 재배여건에 적합한 물 절약형 적정 관개간격 및 1회 관개량을 산정하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.178-178
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• 2023

Drought and flooding have historically coexisted in Korea, occurring at different times and with varying cycles and trends. The drought indicators measured were (PDSI), (SPI), and (SPEI) in order to statistically analyze the annual or periodic drought occurrence and objectively evaluate statistical characteristics such as the periodicity, tendency, and frequency of occurrence of droughts in the Doam watershed. To compute potential evapotranspiration (PET), both Thornthwaite (Thor) and Penman-Monteith (PM) parameterizations were considered, and the differences between the two PET estimators were analyzed. Hence, SPIs 3 and SPIs 6 revealed a tendency to worsen drought in the spring and winter and a tendency to alleviate drought in the summer in the study area. The seasonal variability trend did not occur in the SPIs 12 and PDSI, as it did in the drought index over a short period. As a result of the drought trend study, the drought from winter to spring gets more severe, in addition to the duration of the drought, although the periodicity of the recurrence of the drought ranged from 3 years to 6 years at the longest, indicating that SPIs 3 showed a brief time of around 1 year. SPIs 6 and SPIs 12 had a term of 4 to 6 years, and PDSI had a period of roughly 6 years. Based on the indicators of the PDSI, SPI, and SPEI, the drought severity increases under climate change conditions with the decrease in precipitation and increased water demand as a consequence of the temperature increase. Therefore, our findings show that national and practical measures are needed for both winter and spring droughts, which happen every year, as well as large-scale and extreme droughts, which happen every six years.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.32-32
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• 2023

Incidences of urban flood and extreme heat waves (due to the urban heat island effect) are expected to increase in New Zealand under future climate change (IPCC 2022; MfE 2020). Increasingly, the mitigation of such events will depend on the resilience of a range Nature-Based Solutions (NBS) used in Sustainable Urban Drainage Schemes (SUDS), or Water Sensitive Urban Design (WSUD) (Jamei and Tapper 2019; Johnson et al 2021). Understanding the impact of changing precipitation and temperature regimes due climate change is therefore critical to the long-term resilience of such urban infrastructure and design. Cuthbert et al (2022) have assessed the trade-offs between the water retention and cooling benefits of different urban greening methods (such as WSUD) relative to global location and climate. Using the Budyko water-energy balance framework (Budyko 1974), they demonstrated that the potential for water infiltration and storage (thus flood mitigation) was greater where potential evaporation is high relative to precipitation. Similarly, they found that the potential for mitigation of drought conditions was greater in cooler environments. Subsequently, Jaramillo et al. (2022) have illustrated the locations worldwide that will deviate from their current Budyko curve characteristic under climate change scenarios, as the relationship between actual evapotranspiration (AET) and potential evapotranspiration (PET) changes relative to precipitation. Using the above approach we assess the impact of future climate change on the urban water-energy balance in three contrasting New Zealand cities (Auckland, Wellington, Christchurch and Invercargill). The variation in Budyko curve characteristics is then used to describe expected changes in water storage and cooling potential in each urban area as a result of climate change. The implications of the results are then considered with respect to existing WSUD guidelines according to both the current and future climate in each location. It was concluded that calculation of Budyko curve deviation due to climate change could be calculated for any location and land-use type combination in New Zealand and could therefore be used to advance the general understanding of climate change impacts. Moreover, the approach could be used to better define the concept of urban infrastructure resilience and contribute to a better understanding of Budyko curve dynamics under climate change (questions raised by Berghuijs et al 2020)). Whilst this knowledge will assist in implementation of national climate change adaptation (MfE, 2022; UNEP, 2022) and improve climate resilience in urban areas in New Zealand, the approach could be repeated for any global location for which present and future mean precipitation and temperature conditions are known.

• 한국농공학회지
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• 제41권6호
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• pp.25-32
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• 1999

The purpose of this study is to analyse the accuracy of weather forecasts of temperature, precipitation probability , and sky condition and to evaluate the applicability of weather forecasts for the estimation of potential evapotranspiration for irrigation scheduling. Five weather station s were selected to compare forecasted and measured climatcal data. The error between forecasted and measured temperature was calculated and discussed. The accuracy of temperature forecast using relative frequency of the error was calculated . The temperature forecasting showed considerably high accuracy. Average sunshine hours for forecasted sky conditions were calculated and showed reasonable quality. From the reliability graphs, the forecasting precipation probabililty was reliable. Potential evapotranspirations were calculated and compared using forecast and measured temperatures. The weather forecast is considered usable for irrigation scheculing.

• 한국환경복원기술학회지
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• 제16권3호
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• pp.41-53
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• 2013

The study for the estimation potential natural vegetation was estimated the occurrence probability distribution using geographic information system(GIS) in Bukhansan National Park. Correlation and factor analysis were analyzed to estimate probability distribution. Coefficients were calculated by logistic regression analysis. Correlation coefficients were significantly at the 0.01 level. Commonality of elevation, annual mean temperature, warmth index and potential evapotranspiration were high value, but topographic index was low value. Communities of over the 0.3 points distribution probability, Quercus mogolica communities were the largest area, 76,940,900 $m^2$, Pinus densiflora communities area was 860,800 $m^2$, Quercus acutissima communities area was 500,100 $m^2$ and Quercus variabilis communities area was 1,000 $m^2$, but Q. aliena, Q. serrata, Carpinus laxiflora and Zelcova serrata communities was not appeared. Therefore, potential national vegetation of Bukhansan national park was likely to be Q. mongolica community, P. densiflora community, Q. acutissima community and Q. variabilis community.

• 한국토양비료학회지
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• 제45권6호
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• pp.1153-1156
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• 2012

대관령 지역의 과거 38년간 (1972-2009)의 기상자료를 수집하여 최저한계온도를 추정하였다. 최저한계온도 출현 빈도 추정은 Gumbel의 극한치 확률분포이론을 도입하여 기온자료의 확률분포함수를 도출하여 이루어졌다. 그 결과 저온 출현일 빈도는 작물의 생산안정성과 밀접한 관계가 있기 때문에 조사하였으며, 저온 출현일이 앞당겨질수록 작물을 일찍 심어 안정된 생육을 유지할 수 있어 그 만큼 수량을 높일 수 있을 것으로 판단되었다. 대관령 지역에서 한계 저온 $5^{\circ}C$ 이상이 5일 이상 지속되는 날짜를 보면 4월 3일, 4월 10일, 4월 20일, 4월 28일, 5월 8일로 나타났으며, 한계저온이 나타나는 시기가 앞으로 당겨질수록 그 시기 (한계저온 $5^{\circ}C$ 출현일)가 출현할 확률이 작아지고 재현되는 기간이 길어져, 작물을 재배할 기회가 줄어들어 작물 파종 및 정식이 어렵게 된다. 따라서 재현기간을 순서대로 보면 50, 25, 10, 5, 2년 이었다. 기온 $5^{\circ}C$에 적응하는 저온성 작물 (배추, 샐러리, 토마토, 딸기 등)은 5월 8일 이후에 파종 또는 정식하면 대관령 지역에서 안정된 수량을 얻을 수 있을 것으로 판단되었다.