scholarly journals Estimation of evapotranspiration using a simulation model

2012 ◽  
Vol 9 (2) ◽  
pp. 257-266
Author(s):  
MH Ali ◽  
H Paul ◽  
MR Haque
Keyword(s):  
Water Balance ◽  
Simulation Model ◽  
Standard Error ◽  
Coefficient Of Variation ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Accurate Estimation ◽  
Statistical Parameters ◽  
Budget Model ◽  
Simulation Performance

Practical methods for the accurate estimation of water requirement for irrigated agriculture are essential. Simulation  model is a useful tool to estimate water balance in the crop field. In this study, the BUDGET model was used to  evaluate its performance to simulate water balance in wheat field. The BUDGET model is composed of a set of  validated subroutines describing the various processes involved in water extraction by plant roots and soil water  movement in absence of a water table. The model was run to simulate evapotranspiration values with the actual  observed weather, crop and soil data for three years (2002-2005), obtained from experimental Station of Bangladesh  Institute of Nuclear Agricultural (BINA). The input data of model are separated into four stages and the value of Kc  and root depth are different for each stage. Evaluation of model performance is done with both graphical display and  statistical criteria. The simulated values fall close to 1:1 line, indicating better performance. The statistical parameters  such as standard deviation (SD), standard error (SE), coefficient of variation (CV) of simulated and actual  evapotranspiration values are found 21.07 and 29.23; 4.49 and 6.23; and 38.03 and 50.75, respectively. Both the  standard error and coefficient of variation for simulated values are found lower than the observed values indicating  stability of the model output. The coefficient of determination value (R2 =0.83) is high for this model, which indicates  good simulation performance. The relative error (RE) is 23.28 percent and model efficiency (EF) is 78.95 percent  which means that the simulation of actual evapotranspiration is satisfactory. The value of Index of agreement (IA) is  0.918 which indicates a very good performance of the model. The overall statistical parameters of simulation period  are in satisfactory level. Therefore, the BUDGET model is able to predict actual evapotranspiration for any level of  soil moisture with reasonable accuracy. The model can be used in planning, management and operation of an  irrigation project for judicious use of water with the limited inputs, especially suitable for countries where modeling of  crop yield is needed under water stress conditions.   DOI: http://dx.doi.org/10.3329/jbau.v9i2.11038   J. Bangladesh Agril. Univ. 9(2): 257–266, 2011

scholarly journals Assessing Annual Actual Evapotranspiration Based on Climate, Topography and Soil in Natural and Agricultural Ecosystems

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 20
Author(s):  
Kleoniki Demertzi ◽  
Vassilios Pisinaras ◽  
Emanuel Lekakis ◽  
Evangelos Tziritis ◽  
Konstantinos Babakos ◽  
...  
Keyword(s):  
Water Balance ◽  
Large Scale ◽  
Hydrological Model ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Climate Data ◽  
Natural Ecosystems ◽  
Loading Effects ◽  
Very High ◽  
Of Greece

Simple formulas for estimating annual actual evapotranspiration (AET) based on annual climate data are widely used in large scale applications. Such formulas do not have distinct compartments related to topography, soil and irrigation, and for this reason may be limited in basins with high slopes, where runoff is the dominant water balance component, and in basins where irrigated agriculture is dominant. Thus, a simplistic method for assessing AET in both natural ecosystems and agricultural systems considering the aforementioned elements is proposed in this study. The method solves AET through water balance based on a set of formulas that estimate runoff and percolation. These formulas are calibrated by the results of the deterministic hydrological model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) for a reference surface. The proposed methodology is applied to the country of Greece and compared with the widely used climate-based methods of Oldekop, Coutagne and Turk. The results show that the proposed methodology agrees very well with the method of Turk for the lowland regions but presents significant differences in places where runoff is expected to be very high (sloppy areas and areas of high rainfall, especially during December–February), suggesting that the proposed method performs better due to its runoff compartment. The method can also be applied in a single application considering irrigation only for the irrigated lands to more accurately estimate AET in basins with a high percentage of irrigated agriculture.

scholarly journals Comparative Analysis of METRIC Model and Atmometer Methods for Estimating Actual Evapotranspiration

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Arturo Reyes-González ◽  
Jeppe Kjaersgaard ◽  
Todd Trooien ◽  
Christopher Hay ◽  
Laurent Ahiablame
Keyword(s):  
Water Management ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Accurate Estimation ◽  
Landsat 8 ◽  
Irrigation Water Management ◽  
Clear Sky ◽  
Key Factor ◽  
Landsat 7 ◽  
Metric Model

Accurate estimation of crop evapotranspiration (ET) is a key factor in agricultural water management including irrigated agriculture. The objective of this study was to compare ET estimated from the satellite-based remote sensing METRIC model to in situ atmometer readings. Atmometer readings were recorded from three sites in eastern South Dakota every morning between 8:15 and 8:30 AM for the duration of the 2016 growing season. Seven corresponding clear sky images from Landsat 7 and Landsat 8 (Path 29, Row 29) were processed and used for comparison. Three corn fields in three sites were used to compare actual evapotranspiration (ETa). The results showed a good relationship between ETa estimated by the METRIC model (ETa-METRIC) and ETa estimated with atmometer (ETa-atm) (r2 = 0.87, index of agreement of 0.84, and RMSE = 0.65 mm day−1). However, ETa-atm values were consistently lower than ETa-METRIC values. The differences in daily ETa between the two methods increase with high wind speed values (>4 m s−1). Results from this study are useful for improving irrigation water management at local and field scales.

High-Frequency Yarn Tension Variations in Spinning

1980 ◽  
Vol 102 (1) ◽  
pp. 45-50
Author(s):  
E. Dyson ◽  
G. Afshari
Keyword(s):  
Experimental Investigation ◽  
Periodic Structure ◽  
Coefficient Of Variation ◽  
Rotational Speed ◽  
High Frequency ◽  
Ring Spinning ◽  
Statistical Parameters ◽  
Yarn Tension ◽  
Rotor Spinning

A description of an experimental investigation of the variations in yarn tension during both ring and rotor open-end spinning which have frequencies equal to, or greater than, the rotational speed of the system is given. Typical results are illustrated and discussed both in terms of statistical parameters such as the coefficient of variation and in terms of their spectra. Tension variations during rotor spinning are shown to have, in general, a much less pronounced periodic structure then the corresponding variations during ring spinning.

Differential coding scheme based FSO channel for optical coherent DP-16 QAM transceiver systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shabana Urooj ◽  
Norah Muhammad Alwadai ◽  
Vishal Sorathiya ◽  
Sunil Lavadiya ◽  
Juveriya Parmar ◽  
...  
Keyword(s):  
Simulation Model ◽  
Channel Model ◽  
Optical Signal ◽  
Performance Parameters ◽  
Free Space Optical ◽  
Simulation Performance ◽  
Coding Scheme ◽  
Simulation Results ◽  
Systems Simulation ◽  
Differential Coding

Abstract This article has indicated optical coherent differential polarization (DP) 16 quadrature amplitude modulation (QAM) transceiver systems with free-space optical (FSO) channel in the presence of differential coding scheme. The optical coherent DP 16-QAM receiver executes the reverse process conversion of the optical signal into an electrical one that is detected to the users. The proposed optical coherent DP-16 QAM transceiver systems based FSO channel model with differential coding has been presented and compared with the previous model. However, the simulation results have confidence realization about the superiority of the proposed simulation model. Hence the proposed optical coherent DP-16 QAM transceiver systems simulation model with differential coding is verified and validated the enhancement performance based on simulation performance parameters.

scholarly journals GlobWat – a global water balance model to assess water use in irrigated agriculture

2015 ◽  
Vol 19 (9) ◽  
pp. 3829-3844 ◽  
Author(s):  
J. Hoogeveen ◽  
J.-M. Faurès ◽  
L. Peiser ◽  
J. Burke ◽  
N. van de Giesen
Keyword(s):  
Water Balance ◽  
Water Use ◽  
Open Water ◽  
Water Balance Model ◽  
Green Water ◽  
Balance Model ◽  
Irrigated Agriculture ◽  
High Resolution Data ◽  
Food And Agriculture ◽  
Global Water

Abstract. GlobWat is a freely distributed, global soil water balance model that is used by the Food and Agriculture Organization (FAO) to assess water use in irrigated agriculture, the main factor behind scarcity of freshwater in an increasing number of regions. The model is based on spatially distributed high-resolution data sets that are consistent at global level and calibrated against values for internal renewable water resources, as published in AQUASTAT, the FAO's global information system on water and agriculture. Validation of the model is done against mean annual river basin outflows. The water balance is calculated in two steps: first a "vertical" water balance is calculated that includes evaporation from in situ rainfall ("green" water) and incremental evaporation from irrigated crops. In a second stage, a "horizontal" water balance is calculated to determine discharges from river (sub-)basins, taking into account incremental evaporation from irrigation, open water and wetlands ("blue" water). The paper describes the methodology, input and output data, calibration and validation of the model. The model results are finally compared with other global water balance models to assess levels of accuracy and validity.

scholarly journals GlobWat – a global water balance model to assess water use in irrigated agriculture

2015 ◽  
Vol 12 (1) ◽  
pp. 801-838 ◽  
Author(s):  
J. Hoogeveen ◽  
J.-M. Faurès ◽  
L. Peiser ◽  
J. Burke ◽  
N. van de Giesen
Keyword(s):  
Water Balance ◽  
Water Use ◽  
Open Water ◽  
Water Balance Model ◽  
Green Water ◽  
Balance Model ◽  
Irrigated Agriculture ◽  
Global Soil ◽  
Spatially Distributed ◽  
Global Water

Abstract. GlobWat is a freely distributed, global soil water balance model that is used by FAO to assess water use in irrigated agriculture; the main factor behind scarcity of freshwater in an increasing number of regions. The model is based on spatially distributed high resolution datasets that are consistent at global level and calibrated against values for Internal Renewable Water Resources, as published in AQUASTAT, FAO's global information system on water and agriculture. Validation of the model is done against mean annual river basin outflows. The water balance is calculated in two steps: first a "vertical" water balance is calculated that includes evaporation from in situ rainfall ("green" water) and incremental evaporation from irrigated crops. In a second stage, a "horizontal" water balance is calculated to determine discharges from river (sub-)basins, taking into account incremental evaporation from irrigation, open water and wetlands ("blue" water). The paper describes methodology, input and output data, calibration and validation of the model. The model results are finally compared with other global water balance models.

scholarly journals Hydrodynamic changes of the soil-cactus interface, effective actual evapotranspiration and its water efficiency under irrigation

2017 ◽  
Vol 21 (4) ◽  
pp. 273-278 ◽  
Author(s):  
José E. F. de Morais ◽  
Thieres G. F. da Silva ◽  
Maria G. de Queiroz ◽  
Gherman G. L. de Araújo ◽  
Magna S. B. Moura ◽  
...  
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Water Dynamics ◽  
Soil Water Balance ◽  
Actual Evapotranspiration ◽  
Water Efficiency ◽  
Economic Returns ◽  
Soil Water Dynamics ◽  
Irrigation Depth ◽  
Efficiency Indicators

ABSTRACT The knowledge on soil water dynamics is the basis of crop water management. The soil water balance (SWB) method is used for this purpose. However, its application in cactus may lead to misinterpretation in water efficiency analysis, since it does not consider the amount of water retained in the plant (WRP). This study aimed to evaluate SWB applicability, hydrodynamic changes and water efficiency of forage cactus clones under irrigation. The clones ‘Orelha de Elefante Mexicana’ (OEM), ‘IPA Sertânia’ (IPA) and ‘Miúda’ (MIU) were submitted to irrigation depths (2.5, 5.0 and 7.5 mm) and frequencies (7, 14 and 28 days), in Serra Talhada, PE, Brazil, between March 2012 and August 2013. The SWB was applied, by adding the WRP in the estimate of the effective actual evapotranspiration (ETrEF). The water efficiency indicators were calculated. The actual evapotranspiration on SWB (ETrSWB) overestimated ETrEF and, like other SWB components, it was affected by the factors irrigation depth, frequency and clone. The clone OEM is the most efficient, due to the use of the WRP, while MIU leads to highest gross economic returns for sale of cladodes as seed. As conclusion, the application of the soil water balance method in areas cultivated with cactus species must be accompanied by WRP.

scholarly journals Potential Water Use Conflicts Generated by Irrigated Agriculture in Rhode Island

1988 ◽  
Vol 17 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Arthur Gold ◽  
Thomas Weaver ◽  
Edwin Porter ◽  
James Opaluch
Keyword(s):  
Simulation Model ◽  
Rhode Island ◽  
Water Use ◽  
Irrigation Water ◽  
Economic Value ◽  
Irrigated Agriculture ◽  
Residential Water Use ◽  
Value Of Irrigation Water ◽  
Rates Of Growth ◽  
Residential Water

This study constructs a simulation model to evaluate the potential for conflict among residential and agricultural users of water in southern Rhode Island. The model estimates the profitability of irrigation of turf farms and projects the total use and the economic value of irrigation water. The results indicate that the economic value of irrigation water compares favorably with current residential water prices in the area. In addition, substantial demand for irrigation water is projected. Given current rates of growth in turf acreage and residential water use, there appears to be a significant potential for conflict, particularly given the absence of well developed institutions for allocating water among users.

scholarly journals A new approach to estimating Mean Flow in the UK

2002 ◽  
Vol 6 (4) ◽  
pp. 709-720 ◽  
Author(s):  
M. G. R. Holmes ◽  
A. R. Young ◽  
A. Gustard ◽  
R. Grew
Keyword(s):  
Soil Moisture ◽  
Water Balance ◽  
Accurate Estimation ◽  
Mean Flow ◽  
Time Step ◽  
Runoff Water ◽  
Data Set ◽  
Water Balance Models ◽  
The Uk ◽  
Drying Curve

Abstract. Traditionally, the estimation of Mean Flow (MF) in ungauged catchments has been approached using conceptual water balance models or empirical formulae relating climatic inputs to stream flow. In the UK, these types of models have difficulty in predicting MF in low rainfall areas because the conceptualisation of soil moisture behaviour and its relationship with evaporation rates used is rather simplistic. However, it is in these dry regions where the accurate estimation of flows is most critical to effective management of a scarce resource. A novel approach to estimating MF, specifically designed to improve estimation of runoff in dry catchments, has been developed using a regionalisation of the Penman drying curve theory. The dynamic water balance style Daily Soil Moisture Accounting (DSMA) model operates at a daily time step, using inputs of precipitation and potential evaporation and simulates the development of soil moisture deficits explicitly. The model has been calibrated using measured MFs from a large data set of catchments in the United Kingdom. The performance of the DSMA model is superior to existing established steady state and dynamic water-balance models over the entire data set considered and the largest improvement is observed in very low rainfall catchments. It is concluded that the performance of all models in high rainfall areas is likely to be limited by the spatial representation of rainfall. Keywords: hydrological models, regionalisation, water resources, mean flow, runoff, water balance, Penman drying curve, soil moisture model

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