scholarly journals A Simple Application for Computing Reference Evapotranspiration with Various Levels of Data Availability—ETo Tool

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2203
Author(s):  
Gonçalo C. Rodrigues ◽  
Ricardo P. Braga
Keyword(s):  
Reference Evapotranspiration ◽  
Accurate Method ◽  
Data Availability ◽  
Estimation Methods ◽  
Weather Data ◽  
Irrigated Agriculture ◽  
Limited Data ◽  
Statistical Comparison ◽  
Single Temperature ◽  
Different Levels

Reference evapotranspiration (ETo) estimations may be used to improve the efficiency of irrigated agriculture. However, its computation can be complex and could require numerous weather data that are not always available for many locations. Different methods are available to estimate ETo when limited data are available, and the assessment of the most accurate one can be difficult and time consuming. There are some standalone softwares available for computing ETo but none of them allow for the comparison of different methods for the same or different datasets simultaneously. This paper aims to present an application for estimating ETo using several methods that require different levels of data availability, namely FAO-56 Penman–Monteith (PM), the Original and the three modified Hargreaves–Samani (HS and MHS1, MHS2 and MHS3), Trajkovic (TR) and the single temperature procedure (MaxTET). Also, it facilitates the comparison of the accuracy estimation of two selected methods. From an example case, for where the application was used to compute ETo for three different locations, results show that the application can easily and successfully estimate ETo using the proposed methods, allowing for statistical comparison of those estimations. HS proves to be the most accurate method for the studied locations; however, the accuracy of all methods tends to be lower for costal locations than for more continental sites. With this application, users can select the best ETo estimation methods for a specific location and use it for irrigation purposes.

scholarly journals Comparison of methods for estimation of reference evapotranspiration in North-Central Plateau zone of Odisha

2018 ◽  
Author(s):  
Rajashree Khatua ◽  
S. Pasupalak
Keyword(s):  
Water Management ◽  
Reference Evapotranspiration ◽  
Vital Role ◽  
Estimation Methods ◽  
Weather Data ◽  
Comparison Of Methods ◽  
Central Plateau ◽  
North Central ◽  
The North ◽  
Taylor Methods

Estimation of Evapotranspiration is vital role for proper water management and efficient farming activities. A decision support system (DSS_ET) was developed which supports 22 ET0 estimation methods with varied options for calculation of various intermediate parameters. The objective of the study is to estimate ET0 in the North central Plateau zone of Odisha, using weather data of the respective locality and screening of methods to estimate ET0 close to FAO-56 Penman Monteith method. The FAO-24 Penman(c=1) and Turc methods yielded the highest (5.605 mm/day) and the lowest mean ET0 (4.201 mm/day) respectively. For this zone, the highest ET0 values was found to be 10.32 mm/d for FAO-24 Penman(c=1) method followed by Businger-van Bavel (9.73 mm/d) and FAO-PPP-17-Penman (9.68 mm/d) in the month of May, whereas, lowest ET0 value was found in the month of December (2.54 mm/d) for the Priestly-Taylor method followed by 1982 Kimberly-Penman method (3.07 mm/d). Among all the methods, Penman-Monteith and Priestley-Taylor methods were ranked first and tenth respectively. For this zone, correction factor for Penman-Monteith and 1982 Kimberly-Penman methods approaches to one. The FAO-24 Penman (c=1) and Businger-van Bavel methods give more diversion from FAO-56 Penman-Monteith method.

scholarly journals Reference evapotranspiration during rainy and dry seasons in Mossoró, RN, Brazil

2020 ◽  
Vol 41 (1) ◽  
pp. 109
Author(s):  
Anna Kézia Soares de Oliveira ◽  
Isaac Alves da Silva Freitas ◽  
Tecla Ticiane Félix da Silva ◽  
José Espínola Sobrinho ◽  
Rudah Marques Maniçoba ◽  
...  
Keyword(s):  
Reference Evapotranspiration ◽  
Irrigation Management ◽  
Radiation Temperature ◽  
Estimation Methods ◽  
Irrigated Agriculture ◽  
Data Series ◽  
Climate Conditions ◽  
Daily Data ◽  
Rational Management ◽  
Semi Arid Region

Mossoró, RN, Brazil, is considered one of the fruit growing centers of the Northeast region. This municipality has a persistent water deficit, with the need to develop irrigated agriculture with efficient water use and rational management of irrigation. The objective of this study was to evaluate estimation methods of reference evapotranspiration (ETo) for different climate conditions of Mossoró, comparing them with the standard Penman-Monteith-FAO 56 method. A daily data series of two distinct years, a rainy (2011) and a dry year (2012), was used. The data were obtained from the weather station of the Federal Rural University of the Semi-Arid Region (UFERSA). An analysis was performed to identify methods that best fit those of Penman-Monteith-FAO 56, and for this, ten methods were evaluated using statistical indices. The Penman-Original, Radiation-Temperature, and Hargreaves-Original methods stood out and satisfactorily met ETo estimation for the rainy season, while the Jensen-Haise, Radiation-Temperature, and Hargreaves-Original methods achieved satisfactory performance for the dry season. The Hargreaves-Samani method did not demonstrate viability in the use of ETo estimation, as it was the worst method in both studied periods and is not recommended for irrigation management.

scholarly journals Minimum weather data requirements for estimating reference evapotranspiration

2011 ◽  
Vol 9 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Slavisa Trajkovic ◽  
Vladimir Stojnic ◽  
Milan Gocic
Keyword(s):  
Reference Evapotranspiration ◽  
Data Availability ◽  
Weather Data ◽  
Data Sets ◽  
Southeast Europe ◽  
Humid Climate ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Data Requirements ◽  
Maximum Air Temperature

The International Commission for Irrigation and Drainage (ICID) and Food and Agriculture Organization of the United Nations (FAO) have proposed using the Penman-Monteith method as the standard method for estimating reference evapotranspiration (ET0), and for evaluating other methods. The FAO-56 Penman-Monteith (FAO-56 PM) method requires the numerous weather data that are not available in the most of the stations. The objectives of this study were: first, to estimate errors that can arise if some weather data are not available and have to be estimated; second, to compare the FAO-56 PM ET0 values computed under various levels of data availability; and third, to determine minimum weather data requirements for estimating ET0 without decreasing the acceptable accuracy. For this study, full weather data sets were collected from six humid weather stations from Serbia (Southeast Europe).The main conclusion is that the minimum and maximum air temperature and "local default" value of wind speed are the minimum data requirements necessary to apply the FAO-56 PM method in humid climate.

scholarly journals Estimation of Daily Reference Evapotranspiration from NASA POWER Reanalysis Products in a Hot Summer Mediterranean Climate

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2077
Author(s):  
Gonçalo C. Rodrigues ◽  
Ricardo P. Braga
Keyword(s):  
Bias Correction ◽  
Reference Evapotranspiration ◽  
Estimation Method ◽  
Accurate Method ◽  
Weather Data ◽  
Maximum Temperature ◽  
Weather Variables ◽  
Local Bias ◽  
Southern Portugal ◽  
Weather Stations

This study aims at assessing the accuracy of estimating daily reference evapotranspiration (ETo) computed with NASA POWER reanalysis products. Daily ETo estimated from local observations of weather variables in 14 weather stations distributed across Alentejo Region, Southern Portugal were compared with ETo derived from NASA POWER weather data, using raw and bias-corrected datasets. Three different methods were used to compute ETo: (a) FAO Penman-Monteith (PM); (b) Hargreaves-Samani (HS); and (c) MaxTET. Results show that, when using raw NASA POWER datasets, a good accuracy between the observed ETo and reanalysis ETo was observed in most locations (R2 > 0.70). PM shows a tendency to over-estimating ETo with an RMSE as high as 1.41 mm d−1, while using a temperature-based ET estimation method, an RMSE lower than 0.92 mm d−1 is obtained. If a local bias correction is adopted, the temperature-based methods show a small over or underestimation of ETo (–0.40 mm d−1≤ MBE < 0.40 mm d−1). As for PM, ETo is still underestimated for 13 locations (MBE < 0 mm d−1) but with an RMSE never higher than 0.77 mm d−1. When NASA POWER raw data is used to estimate ETo, HS_Rs proved the most accurate method, providing the lowest RMSE for half the locations. However, if a data regional bias correction is used, PM leads to the most accurate ETo estimation for half the locations; also, when a local bias correction is performed, PM proved the be the most accurate ETo estimation method for most locations. Nonetheless, MaxTET proved to be an accurate method; its simplicity may prove to be successful not only when only maximum temperature data is available but also due to the low data required for ETo estimation.

Flood estimation for ungauged catchments in the Philippines using multiple archival data records

2021 ◽  
Author(s):  
Trevor Hoey ◽  
Pamela Tolentino ◽  
Esmael Guardian ◽  
Richard Williams ◽  
Richard Boothroyd ◽  
...  
Keyword(s):  
Catchment Area ◽  
Daily Rainfall ◽  
The Philippines ◽  
Data Availability ◽  
Estimation Methods ◽  
Annual Maximum ◽  
Ungauged Catchments ◽  
Pearson Type ◽  
Flood Estimation ◽  
Best Fit

&lt;p&gt;Assessment of flood and drought risks, and changes to these risks under climate change, is a critical issue worldwide. Statistical methods are commonly used in data-rich regions to estimate the magnitudes of river floods of specified return period at ungauged sites. However, data availability can be a major constraint on reliable estimation of flood and drought magnitudes, particularly in the Global South. Statistical flood and drought magnitude estimation methods rely on the availability of sufficiently long data records from sites that are representative of the hydrological region of interest. In the Philippines, although over 1000 locations have been identified where flow records have been collected at some time, very few records exist of over 20 years duration and only a limited number of sites are currently being gauged. We collated data from three archival sources: (1) Division of Irrigation, Surface Water Supply (SWS) (1908-22; 257 sites in total); (2) Japan International Cooperation Agency (JICA) (1955-91; 90 sites); and, (3) Bureau of Research and Standards (BRS) (1957-2018; 181 sites). From these data sets, 176 contained sufficiently long and high quality records to be analysed. Series of annual maximum floods were fit using L-moments with Weibull, Log-Pearson Type III and Generalised Logistic Distributions, the best-fit of these being used to estimate 2-, 10- and 100-year flood events, Q&lt;sub&gt;2&lt;/sub&gt;, Q&lt;sub&gt;10&lt;/sub&gt; and Q&lt;sub&gt;100&lt;/sub&gt;. Predictive equations were developed using catchment area, several measures of annual and extreme precipitation, catchment geometry and land-use. Analysis took place nationally, and also for groups of hydrologically similar regions, based on similar flood growth curve shapes, across the Philippines. Overall, the best fit equations use a combination of two predictor variables, catchment area and the median annual maximum daily rainfall. The national equations have R&lt;sup&gt;2&lt;/sup&gt; of 0.55-0.65, being higher for shorter return periods, and regional groupings R&lt;sup&gt;2&lt;/sup&gt; are 0.60-0.77 for Q&lt;sub&gt;10&lt;/sub&gt;. These coefficients of determination, R&lt;sup&gt;2&lt;/sup&gt;, are lower than in some comprehensive studies worldwide reflecting in part the short individual flow records. Standard errors of residuals for the equations are between 0.19 and 0.51 (log&lt;sub&gt;10&lt;/sub&gt; units), which lead to significant uncertainty in flood estimation for water resource and flood risk management purposes. Improving the predictions requires further analysis of hydrograph shape across the different climate types, defined by seasonal rainfall distributions, in the Philippines and between catchments of different size. The results here represent the most comprehensive study to date of flood magnitudes in the Philippines and are being incorporated into guidance for river managers alongside new assessments of river channel change across the country. The analysis illustrates the potential, and the limitations, for combining information from multiple data sources and short individual records to generate reliable estimates of flow extremes.&lt;/p&gt;

Regional Bicycle Network Evaluation and Strategic Planning: A Quantitative Methodological Approach Despite Limited Data Sources for Cycling

2021 ◽  
pp. 036119812110288
Author(s):  
Alex van Dulmen ◽  
Martin Fellendorf
Keyword(s):  
Travel Demand ◽  
Choice Model ◽  
Methodological Approach ◽  
Data Availability ◽  
Data Sources ◽  
Test Case ◽  
Demand Model ◽  
Limited Data ◽  
Demand Models ◽  
Bicycle Infrastructure

In cases where budgets and space are limited, the realization of new bicycle infrastructure is often hard, as an evaluation of the existing network or the benefits of new investments is rarely possible. Travel demand models can offer a tool to support decision makers, but because of limited data availability for cycling, the validity of the demand estimation and trip assignment are often questionable. This paper presents a quantitative method to evaluate a bicycle network and plan strategic improvements, despite limited data sources for cycling. The proposed method is based on a multimodal aggregate travel demand model. Instead of evaluating the effects of network improvements on the modal split as well as link and flow volumes, this method works the other way around. A desired modal share for cycling is set, and the resulting link and flow volumes are the basis for a hypothetical bicycle network that is able to satisfy this demand. The current bicycle network is compared with the hypothetical network, resulting in preferable actions and a ranking based on the importance and potentials to improve the modal share for cycling. Necessary accompanying measures for other transport modes can also be derived using this method. For example, our test case, a city in Austria with 300,000 inhabitants, showed that a shift of short trips in the inner city toward cycling would, without countermeasures, provide capacity for new longer car trips. The proposed method can be applied to existing travel models that already contain a mode choice model.

scholarly journals Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2363
Author(s):  
Rodrigo Dlugosz da Silva ◽  
Marcelo Augusto de Aguiar e Silva ◽  
Marcelo Giovanetti Canteri ◽  
Juliandra Rodrigues Rosisca ◽  
Nilson Aparecido Vieira Junior
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Global Radiation ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Performance Indices ◽  
Excellent Performance ◽  
Study Region ◽  
Temperature Radiation ◽  
And Performance

Aiming at assessing the performance of alternative methods to Penman-Monteith FAO56 for estimating the reference evapotranspiration (ETo) for Londrina, Paraná, Brazil, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tanner-Pelton, Jensen-Haise, Makkink, modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, Linacre, Blaney-Morin, Romanenko, Hargreaves (1974), McCloud, Camargo, Hamon, Kharrufa, McGuiness-Bordne, and Blaney-Criddle were compared to that standard method recommended by FAO. The estimations were correlated by linear regression and assessed by using the Person’s correlation coefficient (r), concordance index (d), and performance index (c) using a set of meteorological data of approximately 40 years. The methods modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, and Linacre should be avoided, as they did not present excellent results. The methods McCloud, Camargo, Hamon, Kharrufa, McGuinness-Bordne, Blaney-Criddle, Hargreaves (1974), Romanenko, and Blaney-Morin were classified as very bad, not being recommended. In contrast, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tenner-Pelton, Jensen-Haise, and Makkink presented excellent performance indices and can be applied in the study region.

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