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Responses of vegetation yield to precipitation and reference evapotranspiration in a desert steppe in Inner Mongolia,China

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Journal of Arid Land 2023年第4期15卷 477-490页

作者： LI Hongfang WANG Jian LIU Hu MIAO Henglu LIU Jianfeng Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station China Institute of Water Resources and Hydropower ResearchBeijing 100038China Institute of Water Resources for Pastoral Area Ministry of Water ResourcesHohhot 010020China Inner Mongolia Hydraulic Research Institute Hohhot 010020China

Drought,which restricts the sustainable development of agriculture,ecological health,and social economy,is affected by a variety of *** is widely accepted that a single variable cannot fully reflect the characteristics of drought *** precipitation,reference evapotranspiration(ET_(0)),and vegetation yield can derive information to help conserve water resources in grassland ecosystems in arid and semi-arid *** this study,the interactions of precipitation,ET_(0),and vegetation yield in Darhan Muminggan Joint Banner(DMJB),a desert steppe in Inner Mongolia Autonomous Region,China were explored using two-dimensional(2D)and three-dimensional(3D)joint distribution *** types of Copula functions were applied to quantitatively analyze the joint distribution probability of different combinations of precipitation,ET_(0),and vegetation *** the precipitation–ET_(0)dry–wet type,the 2D joint distribution probability with precipitation≤245.69 mm/a or ET_(0)≥959.20 mm/a in DMJB was approximately 0.60,while the joint distribution probability with precipitation≤245.69 mm/a and ET_(0)≥959.20 mm/a was approximately ***,the joint return period that at least one of the two events(precipitation was dry or ET_(0)was wet)occurred was 2 a,and the co-occurrence return period that both events(precipitation was dry and ET_(0)was wet)occurred was 5 *** this condition,the interval between dry and wet events would be short,the water supply and demand were unbalanced,and the water demand of vegetation would not be *** addition,when precipitation remained stable and ET_(0)increased,the 3D joint distribution probability that vegetation yield would decrease due to water shortage in the precipitation–ET_(0)dry–wet years could reach up to 0.60–*** future work,irrigation activities and water allocation criteria need to be implemented to increase vegetation yield and the safety of water resources in the desert steppe of Inner Mongolia.

关键词： precipitation reference evapotranspiration vegetation yield Copula functions desert steppe dry and wet events Inner Mongolia

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Modelling reference evapotranspiration using gene expression programming and artificial neural network at Pantnagar,India

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Information Processing in Agriculture 2023年第4期10卷 547-563页

作者： Pangam Heramb Pramod Kumar Singh K.V.Ramana Rao A.Subeesh Division of Irrigation and Drainage Engineering ICAR-Central Institute of Agricultural EngineeringBhopal 462038India Department of Irrigation and Drainage Engineering G.B.Pant University of Agriculture and TechnologyPantnagar 263145India Division of Agricultural Mechanization ICAR-Central Institute of Agricultural EngineeringBhopal 462038India

evapotranspiration is an essential component of the hydrological cycle that is of particular interest for water resource *** quantification is helpful in irrigation scheduling,water balance studies,water allocation,*** of reference evapotranspiration(ET0)using both gene expression programming(GEP)and artificial neural network(ANN)techniques was done using the daily meteorological data of the Pantnagar region,India,from 2010 to 2019.A total of 15 combinations of inputs were used in developing the ET0 *** model with the least number of inputs consisted of maximum and minimum air temperatures,whereas the model with the highest number of inputs consisted of maximum air temperature,minimum air temperature,mean relative humidity,number of sunshine hours,wind speed at 2mheight and extra-terrestrial radiation as inputs and with ET0 as the output for all the *** the GEP models were developed for a single functional set and pre-defined genetic operator values,while the best structure in each ANN model was found based on the performance during the testing *** was found that ANN models were superior to GEP models for the estimation *** was evident from the reduction in RMSE values ranging from 2%to 56%during training and testing phases in all the ANN models compared with GEP *** ANN models showed an increase of about 0.96%to 9.72%of R2 value compared to the respective GEP *** comparative study of these models with multiple linear regression(MLR)depicted that the ANN and GEP models were superior to MLR models.

关键词： Artificial Neural Networks Evolutionary algorithms Gene Expression Programming Machine Learning Regression Analysis reference evapotranspiration models

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Temporal variations of reference evapotranspiration and controlling factors:Implications for climatic drought in karst areas

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Journal of Groundwater Science and Engineering 2022年第3期10卷 267-284页

作者： Xiao-jiao Guo Wen-zhong Wang Cheng-xi Li Wei Wang Jian-sheng Shi Ying Miao Xing-bo Hao Dao-xian Yuan Key Laboratory of Groundwater Sciences and Engineering Ministry of Natural ResourcesInstitute of Hydrogeology and Environmental GeologyChinese Academy of Geological SciencesShijiazhuang 050061China Ecogeological Survey Center of China Geological Survey China Aero Geophysical Survey and Remote Sensing Center for Natural ResourcesBeijing 100083China China University of Geosciences(Wuhan) Wuhan 430074China Key Laboratory of Karst Dynamics Institute of Karst GeologyChinese Academy of Geological SciencesGuilin 541004GuangxiChina Geological Exploration Institute of Shandong Zhengyuan China Metallurgical Geology BureauJinan 250101China Hebei Coal Geology Bureau fourth Geological Brigade Zhangjiakou 075100HebeiChina.

Variations in reference evapotranspiration(ET_(0)) and drought characteristics play a key role in the effect of climate change on water cycle and associated ecohydrological *** accurate estimation of ET_(0) is still a challenge due to the lack of meteorological data and the heterogeneity of hydrological *** there is an increasing trend in extreme drought events with global climate change,the relationship between ET_(0) and aridity index in karst areas has been poorly *** this study,we used the Penman-Monteith method based on a long time series of meteorological data from 1951 to 2015 to calculate ET_(0)in a typical karst area,Guilin,Southwest *** temporal variations in climate variables,ET_(0)and aridity index(AI)were analyzed with the Mann-Kendall trend test and linear regression to determine the climatic characteristics,associated controlling factors of ET_(0) variations,and further to estimate the relationship between ET_(0) and *** found that the mean,maximum and minimum temperatures had increased significantly during the 65-year study period,while sunshine duration,wind speed and relative humidity exhibited significant decreasing *** annual ET_(0) showed a significant decreasing trend at the rate of−8.02 mm/***,significant increase in air temperature should have contributed to the enhancement of ET_(0),indicating an“evaporation paradox”.In comparison,AI showed a slightly declining trend of−0.0005/a during *** change in sunshine duration was the major factor causing the decrease in ET_(0),followed by wind *** had a higher correlation with precipitation amount,indicating that the variations of AI was more dependent on precipitation,but not substantially dependent on the ET_(0).Although AI was not directly related to ET_(0),ET_(0)had a major contribution to seasonal AI *** seasonal variations of ET_(0)played a critical role in dryness/wetness changes to regulate water and energy supply,which

关键词： reference evapotranspiration Aridity index Penman-Monteith method Sunshine duration Guilin

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Climate change trend and its effects on reference evapotranspiration at Linhe Station, Hetao Irrigation District

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Water Science and Engineering 2014年第3期7卷 250-266页

作者： Xu-ming WANG Hai-jun LIU Li-wei ZHANG Rui-hao ZHANG College of Water Sciences Beijing Normal University

Linhe National Meteorological Station, a representative weather station in the Hetao Irrigation District of China, was selected as the research site for the present study. Changes in climatic variables and reference evapotranspiration （ET0 ）（estimated by the Penman-Monteith method） were detected using Mann-Kendall tests and Sen＇s slope estimator, respectively. The authors analyzed the relationship between the ET0 change and each climatic variable＇s change. From 1954 to 2012, the air temperature showed a significant increasing trend, whereas relative humidity and wind speed decreased dramatically. These changes resulted in a slight increase in ETo. The radiative component of total ET0 increased from 50% to 57%, indicating that this component made a greater contribution to the increase in total ETo than the aerodynamic component, especially during the crop growing season （from April to October）. The sensitivity analysis showed that ETo in Hetao is most sensitive to mean daily air temperature （11.8%）, followed by wind speed （-7.3%） and relative humidity （4.8%）. Changes in sunshine duration had only a minor effect on ET0 over the past 59 years.

关键词： climatic variables reference evapotranspiration change trend Mann-Kendall test sensitivity analysis

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Forecasting Multi-Step Ahead Monthly reference evapotranspiration Using Hybrid Extreme Gradient Boosting with Grey Wolf Optimization Algorithm

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Computer Modeling in Engineering & Sciences 2020年第11期125卷 699-723页

作者： Xianghui Lu Junliang Fan Lifeng Wu Jianhua Dong School of Hydraulic and Ecological Engineering Nanchang Institute of TechnologyNanchang330099China Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education Northwest A&F UniversityYangling712100China Faculty of Agriculture and Food Kunming University of Science and TechnologyKunming650500China

It is important for regional water resources management to know the agricultural water consumption information several months in *** reference evapotranspiration(ET_(0))in the next few months is important for irrigation and reservoir *** on forecasting of multiple-month ahead ET_(0) using machine learning models have not been reported ***,machine learning models such as the XGBoost model has multiple parameters that need to be tuned,and traditional methods can get stuck in a regional optimal solution and fail to obtain a global optimal *** study investigated the performance of the hybrid extreme gradient boosting(XGBoost)model coupled with the Grey Wolf Optimizer(GWO)algorithm for forecasting multi-step ahead ET_(0)(1-3 months ahead),compared with three conventional machine learning models,i.e.,standalone XGBoost,multi-layer perceptron(MLP)and M5 model tree(M5)models in the subtropical zone of *** results showed that theGWO-XGB model generally performed better than the other three machine learning models in forecasting 1-3 months ahead ET_(0),followed by the XGB,M5 and MLP models with very small differences among the three *** GWO-XGB model performed best in autumn,while the MLP model performed slightly better than the other three models in *** is thus suggested to apply the MLP model for ET_(0) forecasting in summer but use the GWO-XGB model in other seasons.

关键词： reference evapotranspiration extreme gradient boosting Grey Wolf Optimizer multi-layer perceptron M5 model tree

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Temporal variations of reference evapotranspiration and its sensitivity to meteorological factors in Heihe River Basin, China

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Water Science and Engineering 2015年第1期8卷 1-8页

作者： Jie Zhao Zong-xue Xu De-peng Zuo Xu-ming Wang College of Water Sciences Beijing Normal University

On the basis of daily meteorological data from 15 meteorological stations in the Heihe River Basin （HRB） during the period from 1959 to 2012, long-term trends of reference evapotranspiration （ET0） and key meteorological factors that affect ET0 were analyzed using the Mann- Kendall test. The evaporation paradox was also investigated at 15 meteorological stations. In order to explore the contribution of key meteo- rological factors to the temporal variation of ET0, a sensitivity coefficient method was employed in this study. The results show that：（1） mean annual air temperature significantly increased at all 15 meteorological stations, while the mean annual ET0 decreased at most of sites; （2） the evaporation paradox did exist in the HRB, while the evaporation paradox was not continuous in space and time; and （3） relative humidity was the most sensitive meteorological factor with regard to the temporal variation of ET0 in the HRB, followed by wind speed, air temperature, and solar radiation. Air temperature and solar radiation contributed most to the temporal variation of ETo in the upper reaches; solar radiation and wind speed were the determining factors for the temporal variation of ET0 in the middle-lower reaches.

关键词： reference evapotranspiration Evaporation paradox Meteorological factor Heihe River Basin

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Effects of ENSO and Climate Change on reference evapotranspiration in Southern Vietnam

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Journal of Meteorological Research 2021年第5期35卷 868-881页

作者： Van Viet LUONG Industrial University of Ho Chi Minh City Ho Chi Minh City 71408Vietnam

This study aims to evaluate the effects of climate change and El Nino-Southern Oscillation(ENSO)on reference evapotranspiration(ET_(o))in the climate sub-regions of South Vietnam(SVN)and the role of the related meteorological *** trend analysis shows that ET_(o) has been increasing quite clearly,especially during the rainy *** examining the contribution of meteorological variables to the increase of ET_(o),it is indicated that temperature is the main *** the meteorological variables that are related to ET_(o),temperature is also the factor that has gained the most significant *** of variance reveals that there is no difference in the increase of ET_(o) among the climate sub-regions of *** effect of ENSO on ET_(o) is assessed based on the difference in the mean value of ET_(o) between the El Nino and La Nina *** results show that this difference is most obvious from October to May,and the main factor contributing to the increase is not temperature but sunshine *** difference in sunshine hours between the warm and cold phases in these months is around one hour per day,contributing about58%-86%to the ET_(o) *** analysis of variance shows that ENSO has different levels of influences on ET_(o) in the climate *** to the increase in ET_(o) due to climate change over the past 40 years,the ET_(o) difference between El Nino and La Nina phases is many times *** addition,since the effect of ENSO on ET_(o) is most obvious in the study area during the dry season,it is much *** order to mitigate the effect of ENSO on drought in this area,monitoring and forecasting meteorological variables that have the main contribution to the variation of ET_(o),including the number of sunshine hours,should be promoted.

关键词： climate change climate variability El Nino-Southern Oscillation(ENSO) reference evapotranspiration trend analysis sensitivity analysis

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Determination of reference evapotranspiration Using Penman-Monteith Method in Case of Missing Wind Speed Data under Subhumid Climatic Condition in Hungary

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Atmospheric and Climate Sciences 2022年第2期12卷 235-245页

作者： Zoltán Varga-Haszonits Éva Szalka Tamás Szakál Department of Water and Environmental Sciences Széchenyi István University of Gy&#337 r Mosonmagyaróvár Hungary

The reference evapotranspiration was calculated using Penman-Monteith method proposed. This method was evaluated on data measured by lysimeter in Szarvas experimental station in Hungary. The results of the two methods were in good agreement. However, this method requires an amount of data which is not available at all sites of meteorological measurement. Therefore it was necessary to investigate which elements influencing evapotranspiration are important and which elements are less important. With the help of investigation was indicated that radiation and vapor pressure deficit play important role in determination of reference evapotranspiration. Taking into account this there was two possibilities to calculate evapotranspiration. One of these is to use Penman-Monteith formula with constant wind speed as advised by Allen. Another one is to neglect wind speed data. Both methods were investigated and the method with constant wind speed was found better in a subhumid climatic condition of Hungary.

关键词： reference evapotranspiration Global Radiation Vapor Pressure Deficit Sub Humid Climate Irrigation Requirements of Crops

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Decreasing reference evapotranspiration in a Warming Climate-A Case of Changjiang (Yangtze) River Catchment During 1970-2000

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Advances in Atmospheric Sciences 2006年第4期23卷 513-520页

作者：许崇育龚乐冰姜彤陈德亮 Department of Geosciences University of Oslo P. O Box 1047 BlindernNO-0316 OsloNorway Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008 Department of Earth Sciences Uppsala University Villavagen 16S-75236 UppsalaSweden Department of Earth SciencesGothenburg UniversitySweden Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Department of Earth Sciences Gothenburg University Sweden Laboratory for Climate Studies/National Climate CenterChina Meteorological AdministrationBeijing 100081

This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during 1970-2000 in the Yangtze River catchment. Relative contributions of the four meteorological variables to changes in the reference evapotranspiration are quantified. The results show that both the reference evapotranspiration and the pan evaporation have significant decreasing trends in the upper, the middle as well as in the whole Changjiang （Yangtze） River catchment at the 5% significance level, while the air temperature shows a significant increasing trend. The decreasing trend detected in the reference evapotranspiration can be attributed to the significant decreasing trends in the net radiation and the wind speed.

关键词： reference evapotranspiration Penman-Monteith method temporal trend Changjiang(Yangtze) River catchment China

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Validation and calibration of various reference evapotranspiration alternative methods under the climate conditions of Bosnia and Herzegovina

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International Soil and Water Conservation Research 2017年第4期5卷 309-324页

作者： SabrijaČadro Mirza Uzunović JasminkaŽurovec OgnjenŽurovec Faculty of Agriculture and Food Sciences(PPF) University of Sarajevo(UNSA)Bosnia and Herzegovina Norwegian University of Life Sciences(NMBU) Norway

In Bosnia and Herzegovina(BiH),the number of weather stations(WS)that are monitoring all climatic parameters required for FAO-56 Penman-Monteith(FAO-PM)equation is *** fact,it is of great need and importance to achieve the possibility of calculating reference evapotranspiration(ET_(0))for every WS in BiH(around 150),regardless of the number of climate parameters which they *** this problem is possible by using alternative equations that require less climatological data for reliable estimation of daily and monthly *** main objective of this study was to validate and determine,compared to the FAO-PM method,a suitable and reliable alternative ET0 equations that are requiring less input data and have a simple calculation procedure,with a special focus on Thornthwaite and Turc as methods previously often used in *** fulfill this objective,12 alternative ET0 calculation methods and 21 locally adjusted versions of same equations were validated against FAO-PM ET0 *** climatic data,recorded at sixteen WS,including mean maximum and minimum air temperature(°C),precipitation(mm),minimum and maximum relative humidity(%),wind speed(m s^(−1))and sunshine hours(h)for the period 1961–2015(55 years)were collected and averaged over each *** types of statistical indicators:the determination coefficient(R^(2)),mean bias error(MBE),the variance of the distribution of differences(sd^(2)),the root mean square difference(RMSD)and the mean absolute error(MAE)were used to assess alternative ET_(0) equation *** results,confirmed by various statistical indicators,shows that the most suitable and reliable alternative equation for monthly ET0 calculation in BiH is the locally adjusted Trajkovic *** Hargreaves-Samani method was the second best performing *** two most frequently used ET_(0) calculation methods in BiH until now,Thornthwaite and Turc,were ranked low.

关键词： reference evapotranspiration Limited data FAO-56 Penman-Monteith Calibration Thornthwaite

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