Download or read book Modeling and Forecasting Evapotranspiration for Better Management of Irrigation Command Areas written by Roula Bachour and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It has become very crucial to manage water resources to meet the needs of the growing population. In irrigation command areas, and in order to build a better plan to manage service delivery from canals and reservoirs, it is important to build appropriate knowledge of water needs on a field basis. There is often a lag between the order and delivery of water to the field. Knowledge of the crop water requirement at the field level helps the decision maker to make the right choices leading to more efficient handling of the available water. The purpose of this study was to develop methodologies and tools that allow better management of irrigation water and water delivery systems, such as machine learning models that can be used as tools for decision support systems of water management. To achieve better modeling and prediction, wavelet decompositions were explored for their ability to give information about time and frequency changes in the data. Remote sensing approaches were also used for their ability to quantify water requirements at the spatial level. Therefore, this dissertation explored the use of the above-mentioned data tools and techniques to address water management problems. The framework of this dissertation consisted of three components that provide tools to support irrigation system operational decisions. In general, the results for each of the methods developed were satisfactory, relevant, and encouraging. They provided significant potential for improving decision making for real-time applications in irrigation command areas and better management of the water resources.
Download or read book Evapotranspiration written by Megh R Goyal and published by CRC Press. This book was released on 2013-09-26 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers topics on the basic models, assessments, and techniques to calculate evapotranspiration (ET) for practical applications in agriculture, forestry, and urban science. This simple and thorough guide provides the information and techniques necessary to develop, manage, interpret, and apply evapotranspiration ET data to practical applic
Download or read book Water Management Under Uncertain Conditions written by Tahir Hameed and published by . This book was released on 1994 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comparing Estimates of Actual Evapotranspiration from Satellites Hydrological Models and Field Data written by G. W. Kite and published by IWMI. This book was released on 2000 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of an experiment in which 8 different methods of estimating actual evaporation and transpiration were compared using a common database. Methods based on field data, hydrological models, and satellite data were used and the objectives were to compare results and to assess the utility of each method for various applications.
Download or read book Soil and Water Engineering written by Balram Panigrahi and published by CRC Press. This book was released on 2017-03-03 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling aspects have added a new dimension in research innovations in all branches of engineering. In the field of soil and water engineering, they are increasingly used for planning, development, and management of land and water resources, including analysis of quantity and quality parameters of surface and ground water, flood forecasting and control measures, optimum allocation and utilization of irrigation water. The application of these models saves considerable time in decision support systems and helps in conservation and optimum allocations of scarce precious natural resources.
Download or read book Evapotranspiration Over Heterogeneous Vegetated Surfaces written by Yuting Yang and published by Springer. This book was released on 2015-02-03 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this work is the development of models to estimate evapotranspiration (ET), investigating the partitioning between soil evaporation and plant transpiration at field and regional scales, and calculating ET over heterogeneous vegetated surfaces. Different algorithms with varying complexities as well as spatial and temporal resolutions are developed to estimate evapotranspiration from different data inputs. The author proposes a novel approach to estimate ET from remote sensing by exploiting the linkage between water and carbon cycles. At the field scale, a hybrid dual source model (H-D model) is proposed. It is verified with field observations over four different ecosystems and coupled with a soil water and heat transfer model, to simulate water and heat transfer in the soil-plant-atmosphere continuum. At the regional scale, a hybrid dual source scheme and trapezoid framework based ET model (HTEM), using remote sensing images is developed. This model is verified with data from the USA and China and the impact of agricultural water-saving on ET of different land use types is analyzed, in these chapters. The author discusses the potential of using a remote sensing ET model in the real management of water resources in a large irrigation district. This work would be of particular interest to any hydrologist or micro-meteorologist who works on ET estimation and it will also appeal to the ecologist who works on the coupled water and carbon cycles. Land evapotranspiration is an important research topic in hydrology, meteorology, ecology and agricultural sciences. Dr. Yuting Yang works at the CSIRO Land and Water, Canberra, Australia.
Download or read book Evapotranspiration written by Leszek Labedzki and published by BoD – Books on Demand. This book was released on 2011-03-16 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evapotranspiration is a very complex phenomenon, comprising different aspects and processes (hydrological, meteorological, physiological, soil, plant and others). Farmers, agriculture advisers, extension services, hydrologists, agrometeorologists, water management specialists and many others are facing the problem of evapotranspiration. This book is dedicated to further understanding of the evapotranspiration problems, presenting a broad body of experience, by reporting different views of the authors and the results of their studies. It covers aspects from understandings and concepts of evapotranspiration, through methodology of calculating and measuring, to applications in different fields, in which evapotranspiration is an important factor. The book will be of benefit to scientists, engineers and managers involved in problems related to meteorology, climatology, hydrology, geography, agronomy and agricultural water management. We hope they will find useful material in this collection of papers.
Download or read book Irrigation Scheduling written by Food and Agriculture Organization of the United Nations and published by International Commission. This book was released on 1996 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evapotranspiration written by Stavros Alexandris and published by BoD – Books on Demand. This book was released on 2013-04-30 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evapotranspiration - An Overview contains recent advances in the physics of evaporation and transpiration from a typical experimental site to large scale areas. It incorporates many years of authors experience with the latest research on the methods and the models used worldwide, engaging advanced technology and modern instrumentation. The reader benefits from the in-depth analysis and the diverse sites and settings, where the models, applications and methods are tested. Weather conditions, soil moisture, geology, climatic systems are examined for their role and influence on the theoretical and actual water demand by the atmosphere in the earth's ecosystem. This book not only provides students and scientists with the information to improve the procedures for estimating evapotranspiration, but will also help them to manage and evaluate the observed data.
Download or read book Evapotranspiration written by Salah Er-Raki and published by Nova Science Publishers. This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evapotranspiration (ET) is the total amount of water lost by plant transpiration and soil evaporation. Since about 90% of precipitation received in semi-arid and sub-humid climates is lost to the atmosphere through evapotranspiration, accurate estimations of ET are of crucial need for climate studies, weather forecasts, hydrological surveys, ecological monitoring, and water resource management. This book reviews research on new developments in all areas of evapotranspiration application. It examines the evapotranspiration processes under different environmental and climatic conditions as well as the different methods for modeling and measurement of evapotranspiration at both local and regional scales.
Download or read book Airborne based Evapotranspiration Using MASTER Imagery and the METRIC Model written by Jenna Marie Rodriguez and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved estimates of evapotranspiration (ET) are needed for water resource management and irrigation scheduling. We review the use of imaging spectroscopy to capture estimates of water vapor flux and biophysical components of ET. Remote sensing has long attempted to quantify and predict ET, with most applications relying only on green vegetation indexes from multispectral imagers combined with thermal radiance and weather data. In contrast, imaging spectrometry is an advanced remote sensing technology that measures hundreds of spectral bands in the solar spectrum. Plant pigments, water, and dry matter have unique spectral signatures that can advance estimates of ET and detection of drought stress. This allows analyses based on the physics of spectroscopy and avoids a requirement for continual empirical calibration. These spectral components provide unprecedented information about plant physiological processes, which improve understanding of the regulation of water fluxes and the energy budget. Laboratory, field, and airborne studies of spectral properties in the near- and shortwave-infrared show strong relationships with plant water relations like water content, relative water content, and water potential. Because water absorption features are spectrally independent of pigment absorptions in the visible, they provide a new source of information about environmental conditions. These new observations from imaging spectroscopy will lead to better understanding of ecological and hydrological processes. California agriculture is an invaluable resource to state economic prowess and state food exports across the globe. The almond industry is of special interest as the majority of global almond production is from California, a $2 billion industry. Competing water demands and changing climate trends can exacerbate limited water resources, threatening agricultural productivity and food security at state and global levels. Remote sensing technologies can improve irrigation water management through use of imagery scene-based models to estimate crop evapotranspiration (ETc). This paper addresses the complications of hot and cold pixel selection to calibrate on such model, METRIC (Mapping Evapo-Transpiration with high Resolution and Internalized Calibration), using MASTER imagery in almond orchards. This study does not attempt to validate METRIC results, but instead explores anchor pixel parameters (APPs) by which to calibrate METRIC and improve almond orchard ET estimates.
Download or read book Spatial Variation of Reference Evapotranspiration and its Influence on the Hydrology of Luvuvhu River Catchment Limpopo Province South Africa written by L.R. Singo and published by GRIN Verlag. This book was released on 2016-08-02 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific Study from the year 2016 in the subject Geography / Earth Science - Meteorology, Aeronomy, Climatology, , language: English, abstract: Evapotranspiration (ET) is regarded as the largest mode of water loss in arid and semi-arid areas and is critical for accurate predictions of water exchange and crop productivity. Analysis of spatial and temporal fluctuations of evapotranspiration is therefore crucial to understand the coupled water and energy cycles in arid and semi-arid environments. This study estimated reference evapotranspiration (ETo) to study its influence on the hydrology of Luvuvhu River Catchment using a physically based model. The ETo plays a key role in irrigation systems design, water management under irrigated and rainfed production. The Penman-Monteith equation which is widely used in water resource management and planning was used to estimate ETo. Simulation of ETo was performed using CROPWAT 8.0 software. This algorithm is useful in simulating water resource management scenarios at different spatial and temporal scales under a wide range of environmental conditions. To understand the impact of climatic characteristics in the formulation of evapotranspiration model, seasonal variation of different meteorological parameters such as wind speed, solar radiation, temperature and humidity was analysed. Results showed the spatial and temporal distribution of ETo for different climatic stations in the study area with peaks in summer months. Minimum values of ETo were observed during the dry months. Results from the simulations showed that the areas with higher ETo values were near rivers and streams, which generally have more abundant vegetation. Areas with low ETo values were relatively dry, where pasture and grasslands dominated the landscape. Correlation results showed that no relationship exists between stream flow and ETo (r = 0.36) in the study area, hence, a significant relationship exists between rainfall and ETo (r = 0.86). The study recommends the use of CROPWAT model for computing ETo under arid and semi-arid climatic conditions for water resource management and planning.
Download or read book Irrigation Scheduling written by Food and Agriculture Organization of the United Nations and published by International Commission. This book was released on 1996 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating Crop Evapotranspiration Using a Satellite Remote Sensing Based Energy Balance Model written by Charles Scarborough and published by . This book was released on 2020 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evapotranspiration (ET) is the combination of transpiration from plants and evaporation from land surface sources of water. Accurate accounting of actual crop ET is critical in agricultural water management, especially in areas with intensive irrigation. Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC) is a useful tool to spatially estimate actual evapotranspiration (ETa) using satellite imagery. Although METRIC has been a documented success in estimating ETa in regions around the world, especially the semi-arid regions of the western United States, it has not been applied in the Mid-Atlantic region of the United States or examined under different irrigation regimes like subsurface drip (SDI) and central pivot irrigation (CPI). This study compares cumulative ETa from corn and soybean crops under CPI and SDI crop fields and provides cumulative ETa images of the fields in southern Delaware. METRIC modeled land surface energy balance data and daily ETa (ETMETRIC) were compared to in-situ observations of incoming solar radiation (RS6́3), surface temperature (Ts), net radiation (R℗Ơn), soil heat flux (G), sensible heat flux (H), latent heat flux (LE), Eddy Covariance ETa (ETEC), and atmometer ETa (ETatm). Turbulent fluxes (H and LE) were adjusted to force energy balance closure using the Bowen ratio method. In-situ data measurements were fixed to a Delaware Environmental Observing System (DEOS) station bordering the SDI field in Warrington Farm, a University of Delaware owned irrigation research farm. METRIC analysis and validation were performed over various dates within the 2015, 2016, and 2017 growing seasons. Modeled values of RS6́3, T℗Ơs, G, and LE agreed reasonably well with observations, while Rn and H yielded large biases. Biases in H are in part due to the internal design of METRIC of internal calibration, which absorb all other energy balance biases to yield accurate values of ETa. Daily time series of ETMETRIC from the 2016 study period agreed well with ETEC, indicated by moderate correlation (R2 = 0.63) and low RMSE (0.75 mm day-1). Results from the 2017 study period were unfavorable (R2 = 0.33, RMSE of 1.13 mm day-1). Less than optimal Landsat coverage over the study area contributed to deviations from observations. Cumulative ETMETRIC was 1.5% and 2.9% greater than ETEC for the 2016 and 2017 study periods, respectively. METRIC analysis was able to detect differences in cumulative ETa℗Ơ of corn and soybean under the CPI system and SDI system. Results indicate that METRIC is a useful tool to create spatial estimates of ETa in an agriculturally intensive area of the mid-Atlantic region.
Download or read book Evapotranspiration and Its Role in Water Resources Management written by and published by . This book was released on 1966 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Field Scale Estimation of Evapotranspiration written by Jerry Moorhead and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evapotranspiration (ET) is a major component of the water cycle, which makes it an integral part of water resources management, especially in arid and semiarid environments. ET data are used for water management, irrigation scheduling, various modeling activities, and much more. Some areas of scarce water resources place limitations on water use, which are typically determined from various modeling approaches. As many models use ET as an input, or for validation, accurate ET data is essential to ensure accurate model outputs. In addition, most water management practices are done at the field scale; ET data of a similar scale is needed. Many ET measurement or estimation methods exist and vary widely in approach, instrumentation, complexity, and purpose. A lysimeter is considered the standard for ET measurement and is the most accurate. Other, more portable options are available, such as eddy covariance, scintillometer, Bowen ratio, and remote sensing, all capable of estimating actual field ET within approximately 30% of actual values. Although other methods may not be as accurate as a lysimeter, each has benefits in certain situations. Depending on the purpose, the level of accuracy may be suitable. ET estimation methods are constantly evolving, and accuracy should continually improve further.
Download or read book Modeling the Uncertainty of Evapotranspiration Estimates written by Laureine El Khoury and published by . This book was released on 2011 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Under today's environmental conditions and with the increasing worldwide competition for water, errors in irrigation management decisions can be costly. Therefore, providing both accurate evapotranspiration estimation on a daily basis and estimation of the magnitude of error associated with this estimate is vital for informed water management decisions that allow irrigation managers to account for the associated uncertainties and risks. The present research focuses on the hypothesis, the analytical approach, and the results of a study formulated to quantify the various components of uncertainty in daily and cumulative reference (ET0) and crop (ET[subscript c]) evapotranspiration estimates with and without accounting for serial correlation. These analyses were carried out using nine years of daily (24-h sum) standardized Penman-Monteith values of ET0 downloaded from three CIMIS weather stations in the Sacramento Valley, one year of grass lysimeter data at Five Points, California and measured K[subscript c] using surface renewal, eddy covariance and lysimeter data in our area of interest. Moreover, strategies were developed, based on this study, to reduce the uncertainty in ET estimates. Random and systematic errors associated with CIMIS weather station data and with the Penman-Monteith model itself include: spatial variability of the weather parameters between the farm and the weather station; variations in weather station instrument accuracy; and the intrinsic errors of the daily (24-h sum) standardized PM ET0 model. These sources of error were modeled using Monte Carlo simulation, and the simulated errors were used to modify daily ET0 data for a specific case study in the Sacramento Valley. Modeling of errors in the crop coefficient was not possible given the limited data available; however an estimate of mid-season bias of the crop coefficient for the specific circumstances of the case study was derived from surface renewal data. The mean and standard deviation of simulated ET0 estimates (including the embedded simulated errors) were used to characterize the errors in irrigation scheduling that would result from random, systematic and total errors in ET0 and ET[subscript c] for different irrigation scenarios. The three alternative scenarios considered were represented as three different allowable depletions, 50 mm, 100 mm and 150 mm, between irrigations. Key elements of this research explored the importance of serial correlation in random errors and compared the errors associated with weather station factors with the intrinsic error of the Penman-Monteith model. The research also showed that observed biases in the CIMIS crop coefficient (K[subscript c]) produced a substantially greater effect than errors associated with weather station factors or intrinsic errors in the PM model. The research also found that local measurements of wind speed could considerably increase the accuracy of ET0 estimates.
