Showing papers in "Journal of Irrigation and Drainage Engineering-asce in 1996"
TL;DR: In this paper, a set of procedures and guidelines for assessing integrity, quality, and reasonableness of measured weather data and equipment calibration for automated and electronic agricultural weather stations are presented.
Abstract: Procedures and guidelines are recommended for assessing integrity, quality, and reasonableness of measured weather data and equipment calibration for automated and electronic agricultural weather stations. The procedures include calculation of hourly and 24-h clear sky envelopes for solar radiation, validation of net radiation measurements using calculation equations, and evaluation of expected trends and relationships between air vapor content and air temperature. The procedures for creating clear sky solar radiation envelopes include equations to account for the effects of atmospheric water vapor content and sun angle. Procedures for adjusting air temperature and air vapor content data are introduced to compensate for the aridity of the weather station environment. All of the guidelines are simple and straightforward, and can serve as preliminary “filters” by which to scrutinize weather measurements and as near real-time data flagging procedures for agricultural weather networks.
368 citations
TL;DR: In this article, a finite element method was used to analyze the hydraulics of a lateral and the golden section search was employed to find the operating pressure head of the lateral that can produce the required average emitter discharge along the lateral.
Abstract: A method was developed for the design of microirrigation laterals based on the required average emitter discharge and the required uniformity of water application. The finite-element method was used to analyze the hydraulics of a lateral. The golden section search was employed to find the operating pressure head of the lateral that can produce the required average emitter discharge along the lateral. Analytical results show that the lateral length for the required uniformity of water application may have three solutions and the diameter may have two solutions when laterals are laid on sloped fields. The design procedure was implemented. When the required average emitter discharge, the required uniformity of water application, one parameter—either the lateral length or diameter, and other conditions are given, then the unknown parameter, the best submain position (paired laterals), and the operating pressure head can be accurately obtained using personal computers. A flowchart of the computer program for design of the length of paired laterals is included.
87 citations
TL;DR: In this paper, the authors developed a device to measure simultaneously the pressure difference at the inlet and outlet of a subsurface emitter and the emitter discharge, and they found that discharge rate declines of 10-50% were measured for unplugged subsubsurface emitters.
Abstract: Subsurface drip irrigation has become a common method for the irrigation of field crops, trees, and landscaping. When the predetermined discharge of the emitter is larger than the soil infiltration capacity, water pressure at the dripper outlet increases and can become positive. This pressure buildup in the soil decreases the pressure difference across the dripper and, subsequently, decreases the trickle discharge in a manner that depends on the dripper characteristic curve. A device was developed to measure simultaneously the pressure difference at the inlet and outlet of a subsurface emitter and the emitter discharge. In a preliminary study, discharge rate declines of 10–50% were measured for unplugged subsurface emitters. The extent of the discharge decrease due to back pressure depends on: (1) the soil type (the lower the hydraulic properties the larger the decrease); (2) the dripper discharge (larger decreases occur for higher nominal discharge); (3) possible cavities near the dripper outlet (a larger cavity decreases the back pressure); and (4) the drip system hydraulic properties. The increase in back pressure is rapid at the beginning and then approaches a final value after several minutes, which allows the use of an analytical approximation that assumes steady-state conditions.
77 citations
62 citations
TL;DR: In this article, an empirical root-water uptake model in which the extraction rate varies nonlinearly with the root depth is proposed, and the proposed model performs better than the constant rate models and linearly varying rate models of rootwater uptake.
Abstract: Sound irrigation management requires information about root-water uptake patterns of different crops. In the existing literature, the extraction rate of soil moisture by the roots is assumed to be either constant or varying linearly with the root depth, during the crop period. However, both these models have limited application. With this in view, an empirical root-water uptake model in which the extraction rate varies nonlinearly with the root depth is proposed. Using experimentally obtained soil-moisture depletion values for nonlimiting soil-moisture conditions, it is found that the proposed model performs better than the constant rate models and linearly varying rate models of root-water uptake. Also, constant as well as linear extraction-rate models are found to be particular cases of the proposed model. Based on simulations for limited soil-moisture conditions, it is also found that the frequency of irrigation is sensitive to the use of root-water uptake models.
58 citations
TL;DR: In this article, a univariate analysis based on the concept of relative sensitivity was used to quantify the sensitivity of seven dependent irrigation parameters to variations in field, design, and management variables to save a considerable amount of cost, time, and effort spent in field data collection.
Abstract: Knowledge of the sensitivity of performance and other related dependent furrow-irrigation parameters, in quantitative terms, to variations in field, design, and management variables can help save a considerable amount of cost, time, and effort spent in field data collection. A univariate analysis, based on the concept of relative sensitivity, was used to quantify the sensitivity of seven dependent irrigation parameters (\IE\N\Da\N, \IE\N\Dr\N, \IR\N\Dr\N, \ID\N\Dr\N, \IU\N\Dco\N, l\Idr\N, and \It\N\Da\N) to 13 variables (\It\N\Dco\N, \IS\N\D0\N, σ\D1\N, σ\D2N, ρ\D1\N, ρ\D2\N, \In\N, \Ik\N, \IaN, \Ic\N, l, \Iq\N\Dd0\N, and \IZ\N\Dr\N. Three different data sets, representative of a wide range of irrigation conditions, have been used in the analysis. The response of each dependent parameter to variations in a variable has been evaluated using a zero-inertia model. It was found that no general conclusion can be drawn regarding the relative significance of variables in terms of their effect on each of the dependent parameters, since the interaction between variables is significant enough to weaken or strengthen the effect of changes in a given variable on a dependent parameter. Nevertheless, based on observed relative sensitivity values, a qualitative categorization of variables into five sensitivity classes, with respect to each dependent parameter, was made.
57 citations
TL;DR: In this paper, an analysis was developed showing the relationship between discharge versus the design discharge as a function of emitter characteristics and the soil hydraulic properties and the subsequent effect on irrigation uniformity was examined using soil data from a field in the Arava Valley, Israel.
Abstract: Soil variability can affect the flow rate of water from subsurface trickle emitters. This is because of a buildup of pressure in the soil when water cannot be easily transmitted away from the emitter. In this paper, an analysis was developed showing the relationship between discharge versus the design discharge as a function of emitter characteristics and the soil hydraulic properties. When the design flow volume increases or the hydraulic conductivity of the soil decreases, the pressure head of the soil next to the emitter increases, which reduces the flow rate (other factors remaining equal). The subsequent effect on irrigation uniformity was examined using soil data from a field in the Arava Valley, Israel. The average of the calculated ratio of the actual discharge to the designed discharge was 0.905, 0.825, and 0.704 for designed discharges of 1, 2, and 4 L/h, respectively. Corresponding coefficients of variability were 0.072, 0.124, and 0.193, respectively; likewise Christiansen's uniformities were ...
56 citations
TL;DR: In this article, an extension of a flat bed two-dimensional basin irrigation model to the simulation of irrigation events in basins with micro-topography is presented, which incorporates the local surface slopes in the x and y directions to the governing set of partial differential equations.
Abstract: Microtopography has long been regarded as a key variable affecting basin irrigation performance. This paper reports on the extension of a flat bed two-dimensional basin irrigation model to the simulation of irrigation events in basins with microtopography. The model incorporates the local surface slopes in the x and y directions to the governing set of partial differential equations. Three field experiments were used to validate the extended model. Elevation was measured over irregular grids, and geostatistical techniques were applied to estimate the nodal elevation of the computational grids. Results indicate that inclusion of microtopography improves the estimation of the advance and recession processes and produces lower, more realistic estimates of irrigation performance. To further explore this phenomenon, two numerical experiments were devised consisting of a series of simulations on a level basin with gradually growing microtopography. The times of advance and recession and the irrigation performan...
51 citations
TL;DR: In this article, a vertically integrated, two-dimensional, sharp interface model based on the Galerkin weighted-residual technique was proposed for control of seawater intrusion through a series of injection-extraction wells.
Abstract: Control of seawater intrusion through a series of injection-extraction wells is studied using a vertically integrated, two-dimensional, sharp interface model. The model is based on the Galerkin weighted-residual technique and has been tested against the existing analytical solutions. The model is then cast in terms of the nondimensional parameters, and a series of parametric studies are conducted to obtain the characteristic curves for the cases of a seawater extraction barrier alone and its combination with the freshwater injection barrier. These curves could be used to assess the effect of variations in the input parameters on the position of the seawater-freshwater interface toe position.
48 citations
TL;DR: In this paper, field measurements of water and solute distribution from a point source were made using the gravimetric method and the variables affecting water and Solute distribution, including application rate (1.5, 2.0, and 2.5 L/h), applied volume (15, 20, and 25 L), and input concentration (100, 300, 500 mg/L), were studied and their effects are presented.
Abstract: Field measurements of water and solute distribution from a point source were made using the gravimetric method. The variables affecting water and solute distribution, including application rate (1.5, 2.0, and 2.5 L/h), applied volume (15, 20, and 25 L), and input concentration (100, 300, 500 mg/L) were studied and their effects are presented. There was an increased soil water content both with a higher application rate and applied volume up to about 25 cm depth and 30 cm radial distance, beyond which the difference was not significant. There was a clear relationship between application rate and shape of the wetted soil zone. An increase in rate resulted in an increase in the wetted horizontal area and decrease in the wetted soil depth for the same application volume. Solute concentration increased with higher input concentration, applied volume, and application rate up to about the same depth and radial distance as for soil water content. The wetted and chemigated soil volume was larger for higher volumes applied. This information is useful in the design, operation, and management of a chemigation system with microirrigation.
45 citations
TL;DR: In this paper, simple calendars are described that express best dates of irrigation based on long-term weather data, and the calendars are intended to promote ease and ready adaption of improved water management practices by farmers in both developed and developing countries by presenting simplified, non-technical scheduling guidance.
Abstract: Simple calendars are described that express best dates of irrigation based on long-term weather data. The calendars are intended to promote ease and ready adaption of improved water management practices by farmers in both developed and developing countries by presenting simplified, nontechnical scheduling guidance. The calendars are developed using a daily soil-water balance-crop yield model. Once developed, the calendars require no updating and no further input by technical personnel. Calendars are developed for several planting dates, soil types and initial water contents. Developed calendars graphically show recommended irrigation occurrences expressed in days or weeks after sowing that correspond with the type of irrigation water delivery schedule utilized. The calendars are generalized as much as possible to promote widespread public usability. The graphical nature of the calendars encourages use by illiterate or semiliterate farmers. The methodology demonstrated is transferable to any site where sufficient weather data are available.
TL;DR: In this article, a model to estimate crop evapotranspiration (ETc) by crisphead lettuce using only daily reference ETo data as an input parameter was developed, which calculates crop transpiration and soil evaporation, and also ground cover development and daily radiation interception by the canopy.
Abstract: Crop evapotranspiration ( ETc ) by crisphead lettuce varies considerably with weather conditions and irrigation management Accurate estimates of ETc will enable irrigation applications to be matched more closely to crop requirements, which will reduce excessive applications of irrigation water This is important in the Salinas Valley, Calif, where overpumping of ground water is associated with seawater intrusion and nitrate contamination of local aquifers Accurate assessments of ETc are difficult in crisphead lettuce because of high soil evaporation due to frequent irrigation and slow canopy development A model to estimate ETc for crisphead lettuce using only daily reference evapotranspiration ( ETo ) data as an input parameter was developed The model calculates crop transpiration and soil evaporation, and also ground cover development and daily radiation interception by the canopy The ETc model showed good agreement when compared with field measurements of ETc taken at four different locations in t
TL;DR: In this article, a continuous simulation technique based on the Soil Conservation Service (SCS) method was used to determine annual storm runoff coefficients (ASRCs) for Orlando, Florida using 13 years of daily rainfall data.
Abstract: A continuous simulation technique, based on the Soil Conservation Service (SCS) method, is used to determine annual storm runoff coefficients (ASRCs) for Orlando, Florida using 13 years of daily rainfall data. The ASRC, which is defined as the ratio of annual runoff to annual precipitation, is used to determine annual runoff volume (or depth) and annual pollutant loads in storm-water models under wet conditions. Although simulated ASRC values are very similar to values measured in other studies, they are significantly lower than the values predicted by other existing models. Estimating ASRC values by the continuous modeling approach has several advantages over existing models; relevant watershed characteristics such as soil type, cover, hydrologic condition of the soil, and antecedent moisture conditions neglected in existing models are taken into consideration, and the annual precipitation that does not produce runoff is determined precisely. Meaningful statistical comparisons can be made between the annual pollutant loads estimated using simulated ASRCs. The technique is cost-effective since continuous simulations can be done on spreadsheets, and require easily available daily rainfall data from a nearby climatological station.
TL;DR: In this paper, a sensitivity analysis of potential evapotranspiration (PET) rates under both CO 2 and air temperature changes was conducted, and an additive crop yield model and an optimal irrigation scheduling model were used to maximize agricultural benefits by maximizing crop yield and minimizing irrigation costs.
Abstract: A sensitivity analysis of potential evapotranspiration (PET) rates under both CO\d2 and air temperature changes was conducted. PET was modeled with the Penman-Monteith equation so that the effects of atmospheric CO\d2 concentrations on plant stomatal resistance, and the effects of temperature on land-surface–atmosphere water vapor exchanges were explicitly taken into account. A root-zone soil-water balance was performed using a physically based soil-crop-climate model to analyze the sensitivity of soil moisture to changes in atmospheric temperature and CO\d2 concentrations, and the effects of CO\d2 fertilization on plant photosynthesis and crop yield. A wide spectrum of directional climate change scenarios were analyzed, including both a 3°C increase and a 3°C decrease in air temperature, and both a 50 and a 100% increase in atmospheric CO\d2 concentrations. An additive crop yield model and an optimal irrigation scheduling model were used to maximize agricultural benefits by maximizing crop yield and minimizing irrigation costs. The model was applied to an irrigated potato crop in the San Luis Valley of Colorado.
TL;DR: In this paper, a hydrodynamic model is presented for simulating all the phases of borderstrip irrigation, where the explicit second-order accurate MacCormack scheme is used for solving the governing equations of surface irrigation.
Abstract: In this study, a hydrodynamic model is presented for simulating all the phases of border-strip irrigation. The explicit, second-order accurate MacCormack scheme is used for solving the governing equations of surface irrigation. In this method, the advance and recession fronts need not be considered explicitly and any infiltration equation can be coupled to the surface flow equations easily. The empirical Kostiakov equation (Model 1DKO) and the analytical Parlange equation (Model 1DPA) for infiltration are considered in this study. The implicit Parlange equation is solved using the Newton-Raphson technique. The models are validated using the experimental data available in literature. The present results are also compared with the earlier numerical results based on the characteristic method. A simple subgrid technique is introduced in order to obtain a high grid resolution near the advancing front and at the same time achieve a minimum computational cost. This is based on using two different grid sizes for computation. An equation for the optimum grid size ratio is presented and is validated using numerical experimentation.
TL;DR: In this article, a time of concentration formula for overland flow over a series of planes is derived based on the kinematic-wave equations, which is applicable to a cascade of planes.
Abstract: Based on the kinematic-wave equations, a time of concentration formula for overland flow over a series of planes is derived. The formula is applicable to a cascade of planes, to planes of different roughnesses, to planes of different flow regimes, to planes of different soil types and infiltration rates resulting in different net intensities, to planes subject to different rainfall intensities, and to planes with a combination of all these variables. For practical applications, the formula is developed in terms of the Manning resistance coefficient that is applicable to turbulent or near turbulent flow only. For the series of planes subject to uniform rainfall excess, under the full-area contribution, the corresponding peak discharge formula in terms of the Manning resistance coefficient is derived. This formula can also be used to estimate the peak discharge under the partial-area contribution. The derived formulas are all consistent with the published formulas for a single plane.
TL;DR: In this paper, the authors present a method for determining crop water needs and implement irrigation scheduling programs using an accurate estimate of water use by the crop owners, based on a water usage model.
Abstract: Effective use of water supplies via irrigation requires good methods for determining crop water needs. To implement irrigation scheduling programs requires an accurate estimate of water use by the ...
TL;DR: In this article, three nonstructural management models have been developed and linked together to aid in planning the optimum allocation of land and water resources to achieve the objective of maximizing return in the command area of a canal distributary.
Abstract: Irrigation system planning and management of a semiarid region in Indian Punjab is imperative for sustainable agriculture. For the management of soil and water resources of these regions, three nonstructural management models have been developed and linked together to aid in planning the optimum allocation of land and water resources to achieve the objective of maximizing return in the command area of a canal distributary. A ground-water simulation model uses the mass-balance approach to simulate water-table depths. The seasonal crop water response models are developed to compute crop yields. Interseasonal irrigation system planning models maximize net annual return through conjunctive use of surface water and gypsum-treated sodic ground water to achieve an optimal cropping pattern using a linear programming algorithm. The linear programming models are operated at five water mixing indexes (mixing of surface water and poor quality ground water in different proportions) and seven probability of exceedence levels where rainfall, crop water requirement, and canal water supply are assumed as random variables. These random variables are fitted well to gamma probability density function.
TL;DR: In this article, a finite element method was employed to analyze the pressure head and discharge distributions along laterals and submain, and the golden section search was applied to find the operating pressure heads of the lateral and sub-main corresponding to the required average emitter discharge.
Abstract: A method was developed for designing microirrigation submain units. The lateral discharge equation was used to express the relationship between the discharge and pressure head at the inlet of a lateral to allow a submain unit to be considered as a lateral and a lateral as an emitter. The finite-element method was employed to analyze the pressure head and discharge distributions along laterals and submain. The golden section search was applied to find the operating pressure heads of the lateral and submain corresponding to the required average emitter discharge. When the required average emitter discharge, the required uniformity of water application, one parameter—either the lateral length or diameter, one parameter—either the submain length or diameter, and the field conditions are given, then the unknown parameters, the best submain position (paired laterals), and the operating pressure head of the submain unit can be accurately designed using a personal computer.
TL;DR: In this paper, a variable frequency drive for electric motors has been used to adjust the pump performance to match operating conditions by reducing motor and pump RPMs, which can reasonably match the throttled conditions at a reduced horsepower demand.
Abstract: The constant revolutions per minute (RPM) of electric motors prevents adjusting the pump performance to match variable operating conditions, and thus the pump output is usually reduced or throttled with a valve in the discharge pipe. Variable frequency drives for electric motors have the potential to adjust the pump performance to match operating conditions by reducing motor and pump RPM. Field tests at five sites showed that the pump performance at the reduced RPM could reasonably match the throttled conditions at a reduced horsepower demand. However, pumping plants using a variable frequency drive should be operated at least 500–1,000 h per year to recoup costs.
TL;DR: In this paper, the authors used a sharp interface finite element model to obtain steady-state solutions for the motion of the freshwater-seawater interface due to series of injection wells.
Abstract: Steady-state solutions for the motion of the freshwater-seawater interface due to series of injection wells were obtained using a sharp interface finite element model. The performance of the numerical model was tested with the existing analytical solution. The model was then used to perform the parametric studies on the effects of the location of the series of injection wells, spacing of the wells, and the freshwater injection rate on the seawater intrusion into coastal confined aquifers. The performances of the injection wells in single and double series along the coast were studied and compared. The key variables were grouped into nondimensional parameters, and the relationship between them was presented as a set of characteristic curves. Results indicate that the reduction of seawater intrusion (up to 60–90%) can be achieved through proper selection of the injection rate and spacing between the wells.
TL;DR: In this article, the authors evaluated electroreclamation utilizing subsurface horizontal drainage tubing and parallel electrodes to concentrate and remove nitrates from soil, and found that the concentration in saturated soil tended to increase from anode to cathode after the application of a small direct-current electrical field as the nitrate solution moved toward the cathode.
Abstract: Migration of chemicals in soils to surface or ground water has become a serious threat in many agricultural regions, with nitrates affecting the broadest area due to intensive fertilization and nitrate solubility. This project evaluated electroreclamation utilizing subsurface horizontal drainage tubing and parallel electrodes to concentrate and remove nitrates from soil. Nitrate concentration in saturated soil tended to increase from anode to cathode after the application of a small direct-current electrical field as the nitrate solution moved toward the cathode. When soil moisture content dropped below the saturation level, the nitrate began to migrate toward the anode. Research is recommended to evaluate the effect of a broader range of electrical parameters and analyze the feasibility of commercial application.
TL;DR: The authors in this paper presented the results of the 1994 Advanced Research Workshop on "Sustainability of Irrigated Agri-Agriculture" (Sustainableability of Water Resources Utilization in Agriculture), which was held in Vimeiro, Portugal between 21 and 26 March 1994.
Abstract: The materials presented in this paper are the result of a North Atlantic Treaty Organization (NATO) Advanced Research Workshop on “Sustainability of Irrigated Agriculture (Sustainability of Water Resources Utilization in Agriculture),” which was held in Vimeiro, Portugal between 21 and 26 March 1994. The workshop was cosponsored by the Science and Technology for Development (STD) program of the European Union, Centre International de Hautes Etudes Agronomiques Mediterraneennes (IHEAM), Centre Technique de Cooperation Agricole et Rurale (CTA), Institut Francais de Recherche pour L’ingenierie de L’agriculture et de L’environnement (CEMAGREF) and Junta Nacional de Investigacao cienifica e tecnologica (JNICT). The purpose of that workshop was to provide in-depth discussion on irrigated agriculture among researchers and professionals of different disciplines coming from both developed and developing countries. The workshop objective was to integrate existing science and technology into improved irrigation system performance and agricultural water management, and to provide recommendations for future research directed toward sustainability of water use in agriculture. A total of 43 papers were presented and discussed under the following topics: (1) Sustainability of world irrigation systems; (2) water management and water policies; (3) sustainability of indigenous water and soil conservation systems; (4) irrigation water management and scheduling; (5) on-farm irrigation systems; (6) irrigation scheme management; (7) sustainability and environmental concerns; and (8) technological transfer. The research priorities presented in this paper evolved from group discussions and are based on a common understanding of the challenges that our generation faces to ensure sustainable agricultural development, both in developed and developing countries. The priorities were established by voting of the workshop participants.
TL;DR: In this article, a nonlinear model for the optimum design and operation of drip irrigation systems on flat terrain is presented based on dividing a field into subunits and evaluating various shift patterns and the corresponding pipe and pump sizes in order to identify a minimum cost solution.
Abstract: A nonlinear model for the optimum design and operation of drip irrigation systems on flat terrain is presented in this paper. The analysis is based on dividing a field into subunits and evaluating various shift patterns and the corresponding pipe and pump sizes in order to identify a minimum cost solution. The decision variables are the lengths of two given pipe sizes for the laterals, the diameters of all other pipes, the size of pump, the area and dimensions of subunits, as well as the shift patterns and the irrigation time for each shift and set of subunits irrigated simultaneously. The optimization procedure involves a complete enumeration approach, which minimizes the sum of the capital cost of the system and the present value of operating costs. The model is applied to a case study of a level rectangular field supplied from a ground-water source at its center. The results obtained indicate that one shift operation is the most cost-effective provided the emitter flow rate is above a defined minimum level.
TL;DR: A nonlinear optimization model based on genetic algorithms is developed for land grading design of irregular fields that eliminates the need for parallel shifting of an optimal graded surface by trial and error to adjust the cut-to-fill ratio to a desired value.
Abstract: Design of a successful and efficient surface irrigation system involves land grading as its first step. Land grading is also an effective method for efficient surface drainage. In this research, a nonlinear optimization model based on genetic algorithms is developed for land grading design of irregular fields. The model can be used to obtain plane as well as curved surfaces. In contrast to the available models, the proposed optimization model employs an objective function in which the total volume of earth in cut is minimized. The proposed formulation eliminates the need for parallel shifting of an optimal graded surface by trial and error to adjust the cut-to-fill ratio to a desired value. This is achieved by imposing a constraint on the cut-to-fill ratio. By eliminating the need for such parallel shifting, the optimality of the graded surface is kept undisturbed. Constraints may also be imposed on the shape of the graded surface, slopes of the surface in either direction, elevation of the surface at tur...
TL;DR: In this article, a seasonal furrow irrigation model consisting of submodels to predict irrigation schedule (water balance), irrigation design (surface irrigation hydraulics), and crop yield (yield function) under spatially and temporally variable conditions was developed and verified with the field data.
Abstract: A seasonal furrow irrigation model consisting of submodels to predict irrigation schedule (water balance), irrigation design (surface irrigation hydraulics), and crop yield (yield function) under spatially and temporally variable conditions was developed and verified with the field data. The model was used to predict irrigation performance for each irrigation event during the season, soil moisture before each irrigation, seasonal evapotranspiration (ET), and bean yield along the furrow at 10-m intervals. In addition, measured inputs along the furrow, including heterogeneous infiltration, soil moisture, and yield were used in conjunction with the model to estimate mean (17.3%) and variation in available water-holding capacity (AWC) (15.4%–19.8%). Variation in crop yield represents an integrated effect of variability in infiltration, soil water characteristics, root depth, soil fertility, microclimate, fertilizer and pesticide applications, plants, and disease. Using the calibrated model, nearly 88% of the ...
TL;DR: In this paper, a simulation study of water balance of the cropped area as well as the tank has been done to determine the catchment command area ratio and size of the tank for a five year return period.
Abstract: Design of a runoff-recycling-based irrigation system to provide irrigation for rice in monsoon season is a complex problem. The irrigation requirement, as well as the water availability in the form of runoff, vary both in amount and time. The design of an irrigation system based on the irrigation requirement obtained from short-period experiments may lead to faulty design. To overcome this, a simulation study of water balance of the cropped area as well as the tank has been done to determine the catchment command area ratio and size of the tank for a five year return period. It has been found that for transplanting within optimum period, the catchment command ratio should be 5.0 or more and a tank of storage capacity of 132.6 mm will be sufficient at a return period of five years for the U.P. midhills of India. It has also been found that a short-duration variety will be more suitable for such an irrigation system.
TL;DR: A statewide survey was conducted during 1992 to determine which methods growers used to irrigate their crops in 1991 as discussed by the authors, and the results showed that the amount of land irrigated by surface methods has declined, while the amount irrigation by sprinkler and drip methods has increased.
Abstract: A statewide survey was conducted during 1992 to determine which methods growers used to irrigate their crops in 1991 A questionnaire was distributed to 10,000 of the estimated 80,000 growers in California Respondents represent nearly 6 of the total 1991 irrigated crop land in California A comparison with studies done during 1972 and 1980 showed that the amount of land irrigated by surface methods has declined, while the amount of land irrigated by sprinkler and drip methods has increased The area planted to field crops has declined, while that planted to permanent crops such as fruit and nut trees and grapevines has increased A rapid increase in the use of drip irrigation in vineyards is the most significant change