scholarly journals Reference Evapotranspiration Assessment Techniques for Estimating Crop Water Requirement

2019 ◽  
Vol 8 (4) ◽  
pp. 1094-1100

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.

2020 ◽  
Vol 8 (5) ◽  
pp. 5132-5138

The field study was conducted on Lysimeter by employing the soil water balance method to compute the water requirement and Crop coefficient of Maize in the temperate climatic zone of India. Non-weighing type lysimeters (drainage type) of 2 × 1.5 × 2 m was installed to compute the irrigation requirement, actual crop evapotranspiration (ETc) and actual crop coefficient of maize by water balance method. The water requirement of maize was found 410.4 mm using lysimeter data. The mean daily reference evapotranspiration (ETo) of maize ranged from 0.91 mm/day in the starting growth period to 5.29 mm/day at midseason. The peak ETo of Maize was found 6.3mm/day. The computed crop coefficient (Kc) values of Maize for diffrent crop growth stages were 0.53 for intial, 0.93 for development , 1.05 for mid-season, and 0.78 for late season .A Correlation was also established between Penman-Monteith (P-M) and four other reference Evapotranspiration methods.


2019 ◽  
Vol 13 (3-4) ◽  
pp. 39-50
Author(s):  
Mohannad Alobid ◽  
István Szűcs

Nowadays, nearly 90% of global water consumption is caused by irrigation activities, and more than 40% of the crops are produced under irrigated conditions. This study is an endeavour to estimate the irrigation water requirement (IWR) and crop water requirement (CWR) for some selected crops (Pepper, Eggplant, Potato, Soybean, Maize, Wheat Melon, Lettuce, Sunflower, Broadbean, Citrus, Cherry, Olive tree, Sugarbeet, Artichoke, Wine Grapes, Carrot...etc.) in Sothern Italy. The selected districts (Sant’ Arcangelo) have been taken as a case study area. Demanded meteorologically (rainfall, temperature, humidity, wind speed, sunshine hours) and crop data (crop coefficient and crop calendar) have been collected for 30 years period from 1981 to 2011. FAO CROPWATv8.0 software has been applied for requisite calculation of CWR and IWR along with the developing of cropping patterns. The FAO Penman-Monteith equation is used for estimating the reference evapotranspiration (ET0) by using meteorological data in the framework of CROPWAT model as it regarded as a good evaluator for a wide variety of climatic conditions. The analysis indicates that FAO Penman-Monteith suits very well for the study area and can be successfully used for the estimation of reference evapotranspiration. The important results in this study indicate that the IWR is very low from November to April (wintertime) due to higher rainfall intensity in these months and from month May to October a considerable amount of water is required for irrigation. JEL Classification: Q25, Q24,Q10


Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 172
Author(s):  
Yuan Xu ◽  
Jieming Chou ◽  
Fan Yang ◽  
Mingyang Sun ◽  
Weixing Zhao ◽  
...  

Quantitatively assessing the spatial divergence of the sensitivity of crop yield to climate change is of great significance for reducing the climate change risk to food production. We use socio-economic and climatic data from 1981 to 2015 to examine how climate variability led to variation in yield, as simulated by an economy–climate model (C-D-C). The sensitivity of crop yield to the impact of climate change refers to the change in yield caused by changing climatic factors under the condition of constant non-climatic factors. An ‘output elasticity of comprehensive climate factor (CCF)’ approach determines the sensitivity, using the yields per hectare for grain, rice, wheat and maize in China’s main grain-producing areas as a case study. The results show that the CCF has a negative trend at a rate of −0.84/(10a) in the North region, while a positive trend of 0.79/(10a) is observed for the South region. Climate change promotes the ensemble increase in yields, and the contribution of agricultural labor force and total mechanical power to yields are greater, indicating that the yield in major grain-producing areas mainly depends on labor resources and the level of mechanization. However, the sensitivities to climate change of different crop yields to climate change present obvious regional differences: the sensitivity to climate change of the yield per hectare for maize in the North region was stronger than that in the South region. Therefore, the increase in the yield per hectare for maize in the North region due to the positive impacts of climate change was greater than that in the South region. In contrast, the sensitivity to climate change of the yield per hectare for rice in the South region was stronger than that in the North region. Furthermore, the sensitivity to climate change of maize per hectare yield was stronger than that of rice and wheat in the North region, and that of rice was the highest of the three crop yields in the South region. Finally, the economy–climate sensitivity zones of different crops were determined by the output elasticity of the CCF to help adapt to climate change and prevent food production risks.


Author(s):  
Nikolaj Dobrzinskij ◽  
Algimantas Fedaravicius ◽  
Kestutis Pilkauskas ◽  
Egidijus Slizys

Relevance of the article is based on participation of armed forces in various operations and exercises, where reliability of machinery is one of the most important factors. Transportation of soldiers as well as completion of variety of tasks is ensured by properly functioning technical equipment. Reliability of military vehicles – armoured SISU E13TP Finnish built and HMMWV M1025 USA built were selected as the object of the article. Impact of climatic conditions on reliability of the vehicles exploited in southwestern part of the Atlantic continental forest area is researched by a case study of the vehicles exploitation under conditions of the climate of Lithuania. Reliability of military vehicles depends on a number of factors such as properties of the vehicles and external conditions of their operation. Their systems and mechanisms are influenced by a number of factors that cause different failures. Climatic conditions represent one of the factors of operating load which is directly dependent on the climate zone. Therefore, assessment of the reliability is started with the analysis of climatic factors affecting operating conditions of the vehicles. Relationship between the impact of climatic factors and failure flow of the vehicles is presented and discussed.


2020 ◽  
Vol 148 ◽  
Author(s):  
B. Tinto ◽  
S. Salinas ◽  
A. Dicko ◽  
T. S. Kagone ◽  
I. Traore ◽  
...  

Abstract Although the African continent is, for the moment, less impacted than the rest of the world, it still faces the risk of a spread of COVID-19. In this study, we have conducted a systematic review of the information available in the literature in order to provide an overview of the epidemiological and clinical features of COVID-19 pandemic in West Africa and of the impact of risk factors such as comorbidities, climatic conditions and demography on the pandemic. Burkina Faso is used as a case study to better describe the situation in West Africa. The epidemiological situation of COVID-19 in West Africa is marked by a continuous increase in the numbers of confirmed cases. This geographic area had on 29 July 2020, 131 049 confirmed cases by polymerase chain reaction, 88 305 recoveries and 2102 deaths. Several factors may influence the SARS-CoV-2 circulation in Africa: (i) comorbidities: diabetes mellitus and high blood pressure could lead to an increase in the number of severe cases of SARS-CoV-2; (ii) climatic factors: the high temperatures could be a factor contributing to slow the spread of the virus and (iii) demography: the West Africa population is very young and this could be a factor limiting the occurrence of severe forms of SARS-CoV-2 infection. Although the spread of the SARS-CoV-2 epidemic in West Africa is relatively slow compared to European countries, vigilance must remain. Difficulties in access to diagnostic tests, lack of hospital equipment, but also the large number of people working in the informal sector (such as trading, businesses, transport and restoration) makes it difficult to apply preventive measures, namely physical distancing and containment.


2013 ◽  
Vol 742 ◽  
pp. 331-336
Author(s):  
Ning Yang ◽  
Zhan Xiang Sun ◽  
Jia Ming Zheng ◽  
Dao Cai Chi

Historical characteristics of crop evapotranspiration and irrigation requirement were the bases for determining the irrigation quota in local areas. Based on the trials of two years, crop evapotranspiration and crop coefficient of corn at monthly growth stages were determined and tested by soil water balance method in Fuxin of the southern kerqin sandy land. Using the weather data in Fuxin and Chaoyang from 1953 to 2009, estimated the coupling degree between crop water requirement of λ and apply irrigation water (ETaw) in growing season under three hydrologic years (P=25%,50%and75%).Under the humid year (25%),λ (0.756) in Fuxin was more suitable than Chaoyang (0.694),ETaw(95.5mm) in Fuxin was lower than Chaoyang (148.7mm);under the normal year (50%),λ(0.622) in Fuxin was close to Chaoyang (0.647),ETaw(180.4mm) in Fuxin was higher than Chaoyang (154mm); under droughty year (75%), λ (0.574) in Fuxin was also more suitable than Chaoyang (0.523),ETaw (204.8mm) in Fuxin was also lower than Chaoyang (245mm). The monthly change of λ and ETaw were sharping and influenced irrigation frequency in the growing season of humid and droughty year. The method and results can be further applied to agricultural water management study and guide irrigation in other same regions.


2021 ◽  
Author(s):  
Philip Kuriachen ◽  
Asha Devi ◽  
Anu Susan Sam ◽  
Suresh Kumar ◽  
Jyoti Kumari ◽  
...  

Abstract Climate change and consequent variations in temperature pose a significant challenge for sustaining wheat production systems globally. In this study, the potential impact of rising temperature on wheat yield in the north Indian plains, India's major wheat growing region, was analyzed using panel data from the year 1981 to 2009. This study deviates from the majority of the previous studies by including non-climatic factors in estimating the impact of climate change. Two temperature measures were used for fitting the function, viz., Growing Season Temperature (GST) and Terminal Stage Temperature (TST), to find out the differential impact of increased temperature at various growth stages. Analysis revealed that there was a significant rise in both GST as well as TST during the study period. The magnitude of the annual increment in TST was twice that of GST. Wheat yield growth in the region was driven primarily by increased input resources such as fertilizer application and technological development like improved varieties and management practices. Most importantly, the study found that the extent of yield reduction was more significant for an increase in temperature at terminal crop growth stages. The yield reduction due to unit increase in TST was estimated to be 2.26 % while rise in GST by 1◦C resulted in yield reduction of 2.03%.


2020 ◽  
Vol 2020 (2) ◽  
pp. 21-26
Author(s):  
Sergey Vladimirovich Golovko ◽  
Dmitry Anatolyevich Zadorkin

The article outlines the problem of the influence of climatic factors on the efficiency of solar panels operation. Not long ago the idea of free electricity seemed incredible. However, the development of technologies rapidly progresses, and the alternative energy captures more and more supporters every day. The popularity of solar panels is growing quite rapidly, since photovoltaic converters are an efficient source of electricity. But for more efficient operation of solar cells it is necessary to create the specific conditions, taking into account the location of the unit. There have been considered the factors of more efficient operation of the photovoltaic converters: the hash climatic conditions and the intensity of solar radiation depending on the angle of reducing the impact of the solar rays onto the solar cell surface.


Author(s):  
Jesiele S. Divincula ◽  
Cinara B. da Silva ◽  
Marcio A. L. dos Santos ◽  
Daniella P. dos Santos ◽  
Luan W. dos Santos

ABSTRACT Prickly pear cultivation has played an important role in the Brazilian livestock farming, being used as forage for animals in the Northeast region, especially during the drying season, because it is an excellent source of water. Thus, the objective of this study was to estimate the crop coefficient and water requirement of prickly pear in the Agreste region of Alagoas state, Brazil. Prickly pear crop evapotranspiration (ETc) was determined using five drainage lysimeters, made of polyethylene with dimensions of 0.35 x 0.40 m (side and depth). Four soil layers were separated and put into the lysimeters in the opposite sequence, in order to maintain it as close as possible to the initial soil structure. The reference evapotranspiration (ETo) was estimated by the Penman-Monteith, Hargreaves-Samani and FAO-Radiation methods, using climatic data from the meteorological station of the Instituto Nacional de Meteorologia (INMET) in the city of Arapiraca, AL, Brazil. Crop coefficient (kc) was calculated by the ratio between ETc and ETo. The average kc obtained was 0.72, 0.84 and 0.48 for the Penman-Monteith, Hargreaves-Samani and FAO-Radiation methods, respectively. Keeping the soil under field capacity during the experimental period, the total crop evapotranspiration was 637.84 mm, with daily value equal to 4.22 mm d-1.


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