scholarly journals Comparative evaluation of 24 reference evapotranspiration equations applied on an evergreen-broadleaved forest

2017 ◽  
Vol 49 (4) ◽  
pp. 1028-1041 ◽  
Author(s):  
Athanassios Bourletsikas ◽  
Ioannis Argyrokastritis ◽  
Nikolaos Proutsos
Keyword(s):  
Goodness Of Fit ◽  
Hydrological Cycle ◽  
Reference Evapotranspiration ◽  
Potential Evapotranspiration ◽  
Efficiency Index ◽  
Daily Basis ◽  
Forest Environment ◽  
Statistical Parameters ◽  
Model Efficiency

Abstract Reference evapotranspiration (ET0) is a major component of the hydrological cycle. Its use is essential both for the hydrological rainfall–runoff assessment models and determination of water requirements in agricultural and forest ecosystems. This study investigates the performance of 24 different methods, which produce ET0 or potential evapotranspiration estimates above a grass-covered ground in a Mediterranean forest environment in Greece and compares the derived results with those of the presumed most accurate and scientifically acceptable Penman–Monteith method (ETP-M). Their performance was evaluated on a daily basis for a period of 17 years, using 17 different statistical parameters of goodness of fit. The results showed that some empirical methods could serve as suitable alternatives. More specifically, Copais (ETCOP), Hargreaves original (ETHAR), and Valiantzas2 (ETVA2) methods, exhibited very good values of the model efficiency index, EF (0.934, 0.932, and 0.917, respectively) and the index of agreement, d (0.984, 0.982, and 0.977, respectively). Additionally, the differences of the estimated mean daily value against the respective ETP-M value (rt index) for all methods had a range of −27.8% (Penman – ETPEN) to +59.5% (Romanenko – ETROM), while Copais (ETCOP), Hargreaves–Samani modified1 (ETHS1), and STU (ETSTU) yielded the best values (−0.06%, +0.06%, and 0.22%, respectively).

scholarly journals COMPARAÇÃO ENTRE MEDIDAS EVAPOTRANSPIROMÉTRICAS E METODOLOGIA DA FAO, NA DETERMINAÇÃO DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA

Irriga ◽  
1999 ◽  
Vol 4 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Marco Antonio Lunardi ◽  
Dalva Martinelli Cury Lunardi ◽  
Nariaqui Cavaguti
Keyword(s):  
Standard Error ◽  
Reference Evapotranspiration ◽  
Potential Evapotranspiration ◽  
Moving Average ◽  
Sensible Heat Flux ◽  
Coefficient Of Determination ◽  
Sensible Heat ◽  
Class A ◽  
Class A Pan

COMPARAÇÃO ENTRE MEDIDAS EVAPOTRANSPIROMÉTRICAS E METODOLOGIA DA FAO, NA DETERMINAÇÃO DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA   Marco Antônio LunardiFaculdade de Ciências Agronômicas - UNESP - Campus de Botucatu - Botucatu, SP  CEP 18603-110Dalva Martinelli Cury LunardiDepartamento de Ciências Ambientais - Faculdade de Ciências Agronômicas - UNESP Campus de Botucatu – Botucatu, SP – CEP 18603-110Nariaqui CavagutiDepartamento de Engenharia e Tecnologia Civil - Faculdade de Engenharia Civil UNESP - Campus de Bauru – Bauru, SP – CEP 17033-360   1 RESUMO   Este estudo foi conduzido na área experimental do Departamento de Ciências Ambientais da Faculdade de  Ciências Agronômicas - UNESP, Botucatu -  S.P. (latitude 22o 51’ S, longitude 48o 26’ W, altitude 786 m), no período de 01 de outubro de 1994 a 30 de setembro de 1995.As estimativas diárias da evapotranspiração potencial (ETo), através dos métodos de Penman-Monteith, Penman-FAO, Radiação Solar FAO e Tanque Classe A, foram comparadas com os valores de ETo medidos com 5 (cinco) evapotranspirômetros de lençol freático de nível constante, mantidos a 60 cm de profundidade, em intervalos de 1, 3, 5 e  10 dias nas 04 estações do ano.Os resultados indicaram que esses equipamentos são adequados para a medida da evapotranspiração de referência, não só pela facilidade operacional, mas também por sua precisão. O emprego dos métodos demonstrou ser dependente da estação do ano, da redução do erro padrão de estimativa e do aumento do coeficiente de determinação, como função do intervalo de  tempo  considerado.Todos os métodos indicaram sensibilidade, sempre que a energia  foi utilizada essencialmente na forma de calor sensível, superestimando a evapotranspi- ração nas condições experimentais.O intervalo de 5 a 10 dias apresentou os menores valores de erro padrão e os maiores valores do coeficiente  de determinação, sendo a diferença entre os métodos atribuída aos dados climáticos considerados por cada um.Finalmente os resultados indicaram que os métodos de Penman-Monteith e Penman-FAO determinam com maior precisão a evapotranspiração.   UNITERMOS: evapotranspirômetro, evapotranspiração de referência, métodos de estimativa.   LUNARDI, M.A., LUNARDI, D.M.C., CAVAGUTI, N. COMPARISON BETWEEN EVAPOTRANSPIROMETRIC MEASUREMENT AND FAO METHODOLOGIES IN DETERMINATION OF THE POTENTIAL EVAPOTRANSPIRATION   2 ABSTRACT   In the present work daily potential evapotranspiration values was calculated for Botucatu - S.P. (22o 51’ S, 48o 26’ W, 786m) using Penman Monteith, FAO Penman, FAO Solar Radiation and Class A Pan methods between october, 1984 and september, 1995.The estimating methods was compared with grass reference evapotranspiration obtained with five evapotranspirometers of constant ground water at 60 cm depth, using a moving average of 1 - 10 days on spring, summer, autumn and winter.The study indicates that the equipaments are appropriate for the  evaluation of reference evapotranspiration not only by the operational facilities  but also by the accuracy.The results indicate that the methods applicability is a function of the season of the year, reduction of standard error and  increasing of determination coefficient in the considered intervals.Several estimating methods  showed sensitive even when litlle energy was  utilized in sensible heat flux and overestimated the evapotranspiration in the experimental condition.The 5 -10  days moving average can reduce the standard error of estimate and increase the coefficient of determination significantly between estimated and measured reference evapotranspiration for several estimating methods.Finally, the results indicated that FAO Penman and Penman - Monteith methods are the most realible indication of evapotranspiration.   KEYWORDS: Evapotranspirometer, reference evapotranpiration, estimative methods.

Authenticity of sugar – Identification of plant source and determination of geographical origin of sucrose

2015 ◽  
pp. 40-43 ◽  
Author(s):  
Andreas G. Degenhardt
Keyword(s):  
Metabolic Pathways ◽  
Isotope Ratio ◽  
Geographical Origin ◽  
Hydrological Cycle ◽  
Isotope Ratios ◽  
Saccharum Officinarum ◽  
Mass Spectrometric ◽  
C3 And C4 Plants ◽  
Plant Source

The isotope ratios of water, organic matter and micronutrients from food are dependent on the circumstances and sites of their origin and production. Analytical methods, based on mass spectrometry, are established for routine determination of isotopes. Differentiation between metabolic pathways of C3 and C4 plants is realizable by determination 13C/12C ratios which can distinguish and identify sucrose from pure beet (Beta vulgaris) and pure cane (Saccharum officinarum). Influenced by the worldwide hydrological cycle the isotope ratios of 2H/1H and 18O/16O vary systematically, the variations give information about geographical origin. The exemplarily determination of authenticity is demonstrated by using mass spectrometric isotope ratio evaluation for identification of plant source and geographical origin with the help of selected sugar samples with known origin.

Authenticity of speciality sugars – Determination of carbohydrate source and geographical origin of invert sugar syrup and burnt sugar syrup

2017 ◽  
pp. 87-91
Author(s):  
Andreas G. Degenhardt ◽  
Elke Jansen ◽  
Timo, J. Koch
Keyword(s):  
Geographical Origin ◽  
Hydrological Cycle ◽  
Isotope Ratios ◽  
Saccharum Officinarum ◽  
Invert Sugar ◽  
C4 Plants ◽  
Yeast Fermentation ◽  
Carbohydrate Source ◽  
Sugar Syrup

Modern instrumental analytical methods for the determination of 13C/12C ratios are established to differentiate between metabolic products of C3 and C4 plants. Differentiation and identification of sucrose from pure beet (Beta vulgaris) and pure cane (Saccharum officinarum) are possible without doubt. Influenced by the worldwide hydrological cycle the determination of the isotope ratios of 2H/1H and 18O/16O as well as their variations provide information about geographical origin. Using samples of selected crystal cane sugar (CCS) with known origin, invert sugar syrups (ISS) as well as burnt sugar syrups (BSS) produced therefrom, the authenticity was determined. The speciality sugars ISS and BSS which were made from CCS could be identified as carbohydrates of C4 plants by using 13C/12C Isotope-Ratio Mass Spectrometry (IRMS). In combination with yeast fermentation of ISS and sugar separation from BSS and fermentation into ethanol as well as knowledge about production water, the C2-H/O isotope ratios of ethanol can theoretically determine the geographical origin of the sugars.

scholarly journals Hydrological response to different time scales of climatological drought: an evaluation of the Standardized Precipitation Index in a mountainous Mediterranean basin

2005 ◽  
Vol 9 (5) ◽  
pp. 523-533 ◽  
Author(s):  
S. M. Vicente-Serrano ◽  
J. I. López-Moreno
Keyword(s):  
Time Scales ◽  
Hydrological Cycle ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Drought Indices ◽  
Long Time ◽  
The Standardized Precipitation Index ◽  
Hydrological Droughts ◽  
Different Time Scales

Abstract. At present, the Standardized Precipitation Index (SPI) is the most widely used drought index to provide good estimations about the intensity, magnitude and spatial extent of droughts. The main advantage of the SPI in comparison with other indices is the fact that the SPI enables both determination of drought conditions at different time scales and monitoring of different drought types. It is widely accepted that SPI time scales affect different sub-systems in the hydrological cycle due to the fact that the response of the different water usable sources to precipitation shortages can be very different. The long time scales of SPI are related to hydrological droughts (river flows and reservoir storages). Nevertheless, few analyses empirically verify these statements or the usefulness of the SPI time scales to monitor drought. In this paper, the SPI at different time scales is compared with surface hydrological variables in a big closed basin located in the central Spanish Pyrenees. We provide evidence about the way in which the longer (>12 months) SPI time scales may not be useful for drought quantification in this area. In general, the surface flows respond to short SPI time scales whereas the reservoir storages respond to longer time scales (7–10 months). Nevertheless, important seasonal differences can be identified in the SPI-usable water sources relationships. This suggests that it is necessary to test the drought indices and time scales in relation to their usefulness for monitoring different drought types under different environmental conditions and water demand situations.

Method for the simultaneous quantification of n-hexane metabolites: application to n-hexane metabolism determination

1996 ◽  
Vol 15 (6) ◽  
pp. 497-503 ◽  
Author(s):  
T. Soriano ◽  
M. Menéndez ◽  
P. Sanz ◽  
M. Repetto
Keyword(s):  
Similar Pattern ◽  
Analytical Procedure ◽  
Daily Basis ◽  
Practical Application ◽  
Simultaneous Quantification ◽  
Exposed Workers ◽  
Before And After ◽  
Time Requirements ◽  
The Difference

1 The described analytical procedure permits the simultaneous determination of the main n-hexane meta bolites in urine. 2-Hexanone, 2-hexanol, 2, 5-hexanediol and 2, 5-hexanedione, were chosen to dose the rats used in this study. All urine samples were collected and analysed on a daily basis, before and after acidic hydrolysis (pH 0.1) by GC/MS. 2-Hexanone, 2, 5-dimethylfurane, γ-valerolac tone and 2, 5-hexanedione were determined before hydro lysis ; 2-hexanol and 2, 5-hexanediol, after hydrolysis; and 5-hydroxy-2-hexanone and 4, 5-dihydroxy-2-hexanone were calculated by the difference between γ-valerolactone and 2, 5-hexanedione with and without hydrolysis, respectively. 2 A metabolic scheme was proposed reflecting the biotransformations undergone by the four compounds assayed. We consider 2, 5-dimethylfurane as a 'true metabolite' because the quantities detected were always greater before hydrolysis. 3 It has been reported that human and rat n-hexane metabolism follow a similar pattern. Therefore, as a practical application and without increasing either sample or time requirements, the simultaneous quantifi cation of the different metabolites and their excretion profile could provide better information about the metabolic situation of exposed workers than the determi nation of 2, 5-hexanedione alone. According to our experimental results, 4, 5-dihydroxy-2-hexanone itself would be a good toxicity indicator.

scholarly journals Hydro-Meteorological Trends in an Austrian Low-Mountain Catchment

Climate ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 122
Author(s):  
Gerald Krebs ◽  
David Camhy ◽  
Dirk Muschalla
Keyword(s):  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Remote Sensing Data ◽  
Kendall Test ◽  
Adaptation Measures ◽  
Mitigation And Adaptation ◽  
Regional Impacts ◽  
Long Term Trends ◽  
Annual Scale

While ongoing climate change is well documented, the impacts exhibit a substantial variability, both in direction and magnitude, visible even at regional and local scales. However, the knowledge of regional impacts is crucial for the design of mitigation and adaptation measures, particularly when changes in the hydrological cycle are concerned. In this paper, we present hydro-meteorological trends based on observations from a hydrological research basin in Eastern Austria between 1979 and 2019. The analyzed variables include air temperature, precipitation, and catchment runoff. Additionally, the number of wet days, trends for catchment evapotranspiration, and computed potential evapotranspiration were derived. Long-term trends were computed using a non-parametric Mann–Kendall test. The analysis shows that while mean annual temperatures were decreasing and annual temperature minima remained constant, annual maxima were rising. Long-term trends indicate a shift of precipitation to the summer, with minor variations observed for the remaining seasons and at an annual scale. Observed precipitation intensities mainly increased in spring and summer between 1979 and 2019. Catchment actual evapotranspiration, computed based on catchment precipitation and outflow, showed no significant trend for the observed time period, while potential evapotranspiration rates based on remote sensing data increased between 1981 and 2019.

Climate and land use change impacts on water resources in Sardinia (Italy)

2021 ◽  
Author(s):  
Dario Ruggiu ◽  
Salvatore Urru ◽  
Roberto Deidda ◽  
Francesco Viola
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Land Use Change ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Regional Scale ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Land Use Scenarios ◽  
Near Future

<p>The assessment of climate change and land use modifications effects on hydrological cycle is challenging. We propose an approach based on Budyko theory to investigate the relative importance of natural and anthropogenic drivers on water resources availability. As an example of application, the proposed approach is implemented in the island of Sardinia (Italy), which is affected by important processes of both climate and land use modifications. In details, the proposed methodology assumes the Fu’s equation to describe the mechanisms of water partitioning at regional scale and uses the probability distributions of annual runoff (Q) in a closed form. The latter is parametrized by considering simple long-term climatic info (namely first orders statistics of annual rainfall and potential evapotranspiration) and land use properties of basins.</p><p>In order to investigate the possible near future water availability of Sardinia, several climate and land use scenarios have been considered, referring to 2006-2050 and 2051-2100 periods. Climate scenarios have been generated considering fourteen bias corrected outputs of climatic models from EUROCORDEX’s project (RCP 8.5), while three land use scenarios have been created following the last century tendencies.</p><p>Results show that the distribution of annual runoff in Sardinia could be significantly affected by both climate and land use change. The near future distribution of Q generally displayed a decrease in mean and variance compared to the baseline.   </p><p>The reduction of  Q is more critical moving from 2006-2050 to 2051-2100 period, according with climatic trends, namely due to the reduction of annual rainfall and the increase of potential evapotranspiration. The effect of LU change on Q distribution is weaker than the climatic one, but not negligible.</p>

Spatio-temporal variability of temperature and potential evapotranspiration over India

2016 ◽  
Vol 7 (4) ◽  
pp. 810-822 ◽  
Author(s):  
P. Sonali ◽  
D. Nagesh Kumar
Keyword(s):  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Grid Point ◽  
Rank Correlation ◽  
Trend Detection ◽  
Detection Analysis ◽  
Change Impact ◽  
Spatio Temporal ◽  
Grid Points ◽  
Significant Factors

Worldwide, major changes in the climate are expected due to global warming, which leads to temperature variations. To assess the climate change impact on the hydrological cycle, a spatio-temporal change detection study of potential evapotranspiration (PET) along with maximum and minimum temperatures (Tmax and Tmin) over India have been performed for the second half of the 20th century (1950–2005) both at monthly and seasonal scale. From the observed monthly climatology of PET over India, high values of PET are envisioned during the months of March, April, May and June. Temperature is one of the significant factors in explaining changes in PET. Hence seasonal correlations of PET with Tmax and Tmin were analyzed using Spearman rank correlation. Correlation of PET with Tmax was found to be higher compared to that with Tmin. Seasonal variability of trend at each grid point over India was studied for Tmax, Tmin and PET separately. Trend Free Pre-Whitening and Modified Mann Kendall approaches, which consider the effect of serial correlation, were employed for the trend detection analysis. A significant trend was observed in Tmin compared to Tmax and PET. Significant upward trends in Tmax, Tmin and PET were observed over most of the grid points in the interior peninsular region.

scholarly journals Determination of factor Xa inhibition doses of low-molecular heparin, nadroparin and reviparin in urological patients

2007 ◽  
Vol 64 (8) ◽  
pp. 538-542
Author(s):  
Svetlana Pavlovic ◽  
Sladjana Zivkovic ◽  
Goran Koracevic
Keyword(s):  
Factor Xa ◽  
Surgical Operation ◽  
Moderate Risk ◽  
Statistical Parameters ◽  
Nadroparin Calcium ◽  
The People ◽  
Factor Xa Inhibition ◽  
Significant Difference ◽  
Higher Doses

Background/Aim. The inhibition of factor Xa (FX) by the use of low-molecular heparin (LMH) is important clinical procedure in patients with moderate and high risk for the developament of venous thromboembolism (VTE) and pulmonary embolism (PE). The aim of this study was to determine the level of inhibition of FXa by the use of prophylactic doses of LMH nadroparin-calcium and reviparine-sodium which were applied in urological patients with moderate risk for VTE and PE. Methods. The examination included 80 urological patients divided into 4 groups after urological, uroradiological and anesthesiological preoperative preparation and categorization of anesthesiological risk according to the ASA III classification. The first two groups, of 20 patients each, received the recommended doses of LMH in accordance with the preoperative risk, and an inhibition of FXa 48 hours after the surgical operation and four hours after the administration of LMH was determined. Heptest and homogenous anti-Xa test were used for monitoring of FXa inhibition. Since the obtained anti-Xa values were not satisfactory, two more groups were formed and given double the recommended doses. In these new groups, inhibition of FXa was in recommended range. Standard descriptive statistical parameters were used for describing the charateristics of the people from the formed groups. Results. All the patients examined were clinically estimated as patients of moderate risk, for VTE and PE. There were no statistically singificant difference in body weight of the patients who received nadroparin-calcium 0.3 ml and reviparine-sodium 0.25 ml and those who received their double doses, respectively. The level of FXa inhibition in the group in which the dose of nadroparin-calcium of 0.6 ml was applied was statistically significantly higher than in the group which received the dose of 0.3 ml (Mann-Whitney U test: Z = 5.416; p < 0.0001). The level of FXa in the group given reviparine-sodium 0.5 ml was significantly higher than in the group which received the half of this dose (Mann-Whitney U test: Z = 5.416; p < 0.0001). This research did not confirm a statistically significant difference in the levels of FXa inhibition in patients who received nadroparincalcium as VTE and PE prophilaxis in the dose of 0.6 ml and those who received reviparin-sodium 0.5 ml (in two doses of 0.25 ml) (Mann-Whitney U test: Z = 0.163; p > 0.05). Conclusion. According to biochemical monitoring, the recommended doses of LMH are insufficient for the prophylactic inhibition of FXa in urological pateints with moderate risk for VTE and PE, so the higher doses which inhibit FXa are recommended. .

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