Spatiotemporal variability of reference evapotranspiration and contributing climatic factors in China during 1961–2013

Reference evapotranspiration (ET0) is a key component of hydrologic cycle and it is important for water resources management. Analysis of ET0 changes is particularly critical for understanding the impacts of climatic change on hydrology in ecologically fragile regions. In this study, using the Penman–Monteith method and the Mann–Kendall test, the variation characteristics of ET0 on the Tibetan Plateau (TP) from 1970 to 2018 was analyzed, and the dominant climatic factors controlling the change of ET0 was also explored. The result shows that in TP region: (1) there was an abrupt change in the trend of ET0 around 1997, and the ET0 declined at a rate of −25.9 mm/decade during 1970–1996 but increased by 31.1 mm/decade during 1997–2018; (2) ET0 is most sensitive to solar radiation, then relative humidity, wind speed and mean temperature; (3) the decrease of ET0 before 1997 was mainly due to the decline of wind speed and the increase of relative humidity, while the increase of ET0 after 1997 was mainly due to the decrease of relative humidity. The results of this study can provide data reference for the research of water balance on the TP.

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Spatiotemporal Variations of Reference Evapotranspiration and Its Determining Climatic Factors in the Taihang Mountains, China

Water ◽

10.3390/w13213145 ◽

2021 ◽

Vol 13 (21) ◽

pp. 3145

Author(s):

Tingting Kang ◽

Zeng Li ◽

Yanchun Gao

Keyword(s):

Climate Change ◽

Land Surface ◽

Reference Evapotranspiration ◽

Climatic Factors ◽

Sunshine Duration ◽

High Elevation ◽

Lower Sensitivity ◽

Effective Measure ◽

The Impact ◽

The Relationship

Reference evapotranspiration (ETo) is an effective measure of atmospheric water demand of the land surface. In-depth investigations of the relationship between ETo and primary climatic factors can facilitate the adaptable agriculture and optimize water management, especially in the ecologically fragile Taihang Mountains (THM). This work assessed the spatiotemporal dynamics of ETo and its driving climatic factors from 1973 to 2016 in THM. Results showed: (1) Annual ETo slightly increased during 1973–2016; relative humidity (RH) decreased more slowly, the temperature increased more rapidly, and wind speed (WS) decreased more rapidly at higher elevation than those at lower elevations; (2) two breakpoints occurred in ETo series at 1990 and 1997, and an “evaporation paradox” existed in 1973–1990; (3) ETo at higher elevations had greater sensitivity to changes in RH and lower sensitivity to changes in Tmax and WS. Sensitivity of ETo to minimum air temperature (Tmin) at middle elevations was lowest among three elevation bands; (4) RH and sunshine duration (SD) were the dominant climatic factors of ETo for most periods and stations. This study helps us understand the impact of climate change on ETo in mountainous areas and confirms reference evapotranspiration in high-elevation areas is particularly sensitive to climate change.

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Comparison of FAO Crop Reference Estimates and Radiation based Estimates for Daily Reference Evapotranspiration Estimation

10.5194/egusphere-egu21-14622 ◽

2021 ◽

Author(s):

Rouhin Mitra ◽

Mekonnen Gebremichael ◽

Isabel Franco Trigo ◽

Henk A.R. de Bruin

Keyword(s):

Water Demand ◽

Reference Evapotranspiration ◽

Climatic Factors ◽

Agricultural Practice ◽

Dry Land ◽

Dense Networks ◽

Irrigation Water Demand ◽

Evapotranspiration Estimation ◽

Monteith Equation

<p>Reference evapotranspiration (ETo), a hypothetical concept to estimate evapotranspiration from irrigated and large grass fields is crucial in finding the irrigation water demand in places with extensive agricultural practice. In general, the FAO method (based on the Penman-Monteith equation) is used to estimate ETo from stations that are placed in locations that violate the requirements for reference evapotranspiration. In this study we compare radiation-based methods used to estimate reference evapotranspiration such as ETo De Bruin and ETo Makkink with more conventional ETo approaches in FAO PM method and Priestley Taylor method using in-situ measurements from stations placed in two different settings: (1) Areas that are well-irrigated but surrounded by dry land, (2) Areas that are dry but extensive. We use two spatially dense networks of stations: 1) CIMIS stations of California located in irrigated and in-extensive fields, (2) MESONET stations of Oklahoma located on dry surfaces. &#160;We analyze the differences in the ETo estimates and hypothesize that the radiation-based estimates give more accurate results in the conditions given above for irrigation advisory. We also assess the spatial variability of the different ETo estimates and attempt to investigate the reason behind the differences in these estimates due to the climatic factors.</p>

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Spatiotemporal variability of sunshine duration and influential climatic factors in mainland China during 1959–2017

International Journal of Climatology ◽

10.1002/joc.6580 ◽

2020 ◽

Vol 40 (15) ◽

pp. 6282-6300

Author(s):

Jinghua Xiong ◽

Zhaoli Wang ◽

Chengguang Lai ◽

Yaoxing Liao ◽

Xushu Wu

Keyword(s):

Climatic Factors ◽

Sunshine Duration ◽

Mainland China ◽

Spatiotemporal Variability

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Evaluation of Water Provision Ecosystem Services Associated with Land Use/Cover and Climate Variability in the Winike Watershed, Omo Gibe Basin of Ethiopia

Environmental Management ◽

10.1007/s00267-021-01573-9 ◽

2021 ◽

Author(s):

Abreham Berta Aneseyee ◽

Teshome Soromessa ◽

Eyasu Elias ◽

Tomasz Noszczyk ◽

Gudina Legese Feyisa

Keyword(s):

Land Use ◽

Ecosystem Services ◽

Water Resource Management ◽

Reference Evapotranspiration ◽

Climatic Factors ◽

Spatial And Temporal Variation ◽

Water Yield ◽

Forest Land ◽

Input Parameters ◽

Water Provision

AbstractThe provision of freshwater is essential for sustaining human life. Understanding the water provision modelling associated with the Land Use/Cover (LUC) change and climatic factors is vital for landscape water resource management. The Winike watershed is the largest tributary in the upper Omo Gibe basin of Ethiopia. This research aims to analyze the spatial and temporal change in the water yield to investigate the water yield contribution from the watershed based on the variation in input parameters. The Integrated Valuation of Ecosystem Services and Tradeoffs Tool (InVEST) water yield model was used to evaluate the spatial and temporal variation of the water yield in different years (1988, 1998, 2008 and 2018). The data required for this model include LUC data from satellite images, reference evapotranspiration, root depth, plant available water, precipitation, season factor (Z), and a biophysical table. The analysis of LUC change shows a rapid conversion of grazing land, shrubland, and forest land into cultivated land. There has been a significant variation in water provision, which increased from 1.83 × 109 m3 in 1988 to 3.35 × 109 m3 in 2018. Sub-watersheds 31, 32, and 39 in the eastern part of the watershed contributed more water due to higher precipitation and lower reference evapotranspiration. The major increase in the contribution of water yield was in built-up land by 207.4%, followed by bare land, 148.54%, and forest land by 63%. Precipitation had a greater impact on water yield estimation compared with the other input parameters. Hence, this research helps decision-makers to make informed decisions regarding new policies for LUC change improvement to maintain the water resources in the Winike watershed.

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Reference Evapotranspiration Assessment Techniques for Estimating Crop Water Requirement

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d6738.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 1094-1100

Keyword(s):

Reference Evapotranspiration ◽

Climatic Factors ◽

Crop Coefficient ◽

Climatic Conditions ◽

Water Requirement ◽

Growth Stages ◽

Climatic Data ◽

Water Demands ◽

Conventional Methods ◽

The Impact

Water scarcity is a serious issue that has to be addressed in order to face the increasing water demands. Due to this issue, agricultural crops do not receive the required amount of water. So, it is necessary to have a proper technique to determine the water requirement for a particular crop. Evapotranspiration (ET), a process which is reliant on numerous climatic conditions, quantifies the loss of water from soil and crops through evaporation and transpiration processes respectively. Reference evapotranspiration ET is a concept of estimating ET from the reference surface which resembles an in-depth surface of green grass of stable height, actively growing, fully shading the surface with sufficient water. The amount of water required for a crop is thus determined by multiplying ETo with the crop coefficient (Kc) which depends on the growth stages and duration of a crop. So, evapotranspiration is considered to be one of the successful approaches to optimize the usage of water for crops. A literature survey is carried out on the popular methods of estimating ETo and their merits, demerits are discussed in this paper. Also, the impact of various climatic factors on ETo is presented. From the survey, it is known that ETo is estimated using conventional and non-conventional methods like Penman-Monteith, Blaney-Criddle, Hargreaves, ANN and WNN, regression and fuzzy logic. Humidity, temperature, wind speed, and solar radiation are the factors that have a major impact on estimating ETo. Generally, conventional methods are tedious since it requires experimental setups and more climatic data to determine ETo which are not available in many under developing countries. Thus, in this case, non-conventional methods are found to yield better results from the survey.

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Spatiotemporal variation in reference evapotranspiration and its contributing climatic factors in China under future scenarios

International Journal of Climatology ◽

10.1002/joc.6429 ◽

2020 ◽

Vol 40 (8) ◽

pp. 3813-3831 ◽

Cited By ~ 2

Author(s):

Jincai Zhao ◽

Haibin Xia ◽

Qun Yue ◽

Zheng Wang

Keyword(s):

Reference Evapotranspiration ◽

Climatic Factors ◽

Spatiotemporal Variation ◽

Future Scenarios

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Assessing the Impact of Climate on Actual Crop Water Use over Irrigated Rice and Rape in East China Plain over Four Decades

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.256-259.2557 ◽

2012 ◽

Vol 256-259 ◽

pp. 2557-2564

Author(s):

Mohamed Khaled Salahou ◽

Xiu Ju Zhang

Keyword(s):

Water Use ◽

Management Practices ◽

Reference Evapotranspiration ◽

Water Cycle ◽

Climatic Factors ◽

East China ◽

Crop Water ◽

Irrigated Rice ◽

Crop Water Use ◽

The Impact

Evapotranspiration (ET) is an important component of the water cycle at field, regional and global scales. This study used measured data from a 40-year (1970–2009) in the East China plain on Rape and Rice to analyze the impacts of climatic factors on actual crop water use and crop yield. The results showed that grass reference evapotranspiration (ET0, calculated by FAO Penmen Monteith method) was relatively constant from 1970 to 2009. Average seasonal crop water use was 250 mm and 154 mm for Rice and Rape, respectively, over the four decades. The seasonal decrease in crop water use was around 1.4 mm per season for Rice, and 0.08 mm per season for Rape. Average seasonal effective rain was 456 mm and 120 mm for Rice and Rape, respectively, over the four decades. The seasonal increase in effective rain was around 0.7 mm per season for Rice, and 0.03 mm per season for Rape. The result showed that over the four decades actual crop water use decrease much greater than the increase in effective rainfall. The results also showed that with new cultivars and improved management practices it was possible to further increase grain production without much increase in water use.

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