Water Management of Irrigated-Drained Fields in the Jordan Valley South of Lake Kinneret

The Jordan Valley is one of the primary regions for growing winter crops of fruit and vegetables in Israel and Jordan. Control of water management in these fields is obtained by solid-set irrigation systems and subsurface drainage. Detailed field observations were conducted at a location near the Jordan River, south of Lake Kinneret. Water table heights were measured by approximately 100?piezometers. An exiting wide spacing (160?m) subsurface drainage system was monitored and the total drainage discharge from this regional drainage system to Lake Kinneret was measured. Rainfall, irrigation, and evapotranspiration rates were measured and overall hydrological balance was conducted. The old irrigation method in the region was border irrigation with very high leaching fraction and poor irrigation efficiency. During the 1970s the irrigation method was changed to computer operated drip irrigation. The leaching fraction was reduced and irrigation efficiency increased. Reduction of the total drainage discharge to Lake Kinneret by a factor of about 10 was observed. Water table rise under hand moving sprinkler and soil-set drip irrigation methods were measured and compared for assessment of salinization of the root zone by upward movement of groundwater. The result indicates the strong effect of irrigation time interval on the extent of these rises. The effect of irrigation mode on the extent of water table rises was measured at the field by comparing that under hand moving sprinkler irrigation to that under water solid set drip method. This effect depends, among other variables, on the irrigation time interval, a fact which complicates prediction of water table rise under different irrigation practices. These field results support previous theoretical analysis by the writers and highlighted the interrelationship between irrigation practice and drainage design. The effect of water table drawdown towards the Jordan River was monitored and found to be about 4.6%. The strong influence of the Jordan River on water table height at the drained field is magnified by the existence of sandy layers in the soil profile. This observed gradient may be used for the estimation of lateral seepage flow from the irrigated agricultural field towards the adjacent Jordan River. This study provides a useful source of data for future studies in similar situations.     

Contribution of Evapotranspiration Reduction during Sprinkler Irrigation to Application Efficiency

The effect of reduced corn evapotranspiration (ET) during solid-set sprinkler irrigation on application efficiency was analyzed on two subplots. During each irrigation event, one subplot was irrigated (moist treatment) while the other was not (dry treatment). ET (weighing lysimeter) and transpiration (heat balance method) rates were determined at each subplot before, during, and after the irrigations. During daytime irrigations, there was a significant decrease in ET (32–55%) and transpiration (58%) for the moist treatment. After the irrigations (1–2?h), ET significantly increased (34%) and transpiration decreased (20%). Gross wind drift and evaporation losses (WDELg) were found to be 19.3% of the applied water. Taking into account the ET changes during and after the irrigations, net sprinkler evaporation losses (SELn) were 14.4–17.5% of the applied water. During nighttime irrigations, changes in ET and transpiration were almost negligible, and SELn were slightly greater than WDELg (9.5 and 8.1%, respectively, of applied water). SELn was mainly a function of wind speed. Reduced ET and transpiration during daytime irrigations moderately increased solid-set sprinkler application efficiency.     

Allocation of Flow to Plots in Pressurized Irrigation Distribution Networks: Analysis of the Clément and Galand Method and a New Proposal

This article reviews the method for allocating flow to irrigation plots proposed by Clément and Galand in (1979). Mention is made of its shortcomings, such as the lack of consideration given to the specific technical and economic factors governing current pressurized (drip or sprinkler) irrigation systems and how they provide water to plots. We propose a method for fixed irrigation systems, which takes into account the irrigation method on the plot and the existence of an optimum block area. The result is to allocate a constant flow of water to plots up to an established value of maximum surface area. From there on, we propose applying linear increases related to the total plot area. We also present a formula for calculating the maximum number of blocks based on variables that are easily obtainable during the project phase.     

SIMGRO, a GIS-Supported Regional Hydrologic Model in Irrigated Areas: Case Study in Mendoza, Argentina

The SIMGRO hydrologic simulation model was extended to include irrigation practice. It could then be used to evaluate the effect of hydrologic changes in an irrigated area in the province of Mendoza, Argentina where, given an average annual rainfall of approximately 200?mm, irrigation is crucial for agriculture. A storage dam was recently constructed in the Mendoza River to control the fluctuating river flow and to guarantee that the demand for water is met throughout the year. The dam will impact on parts of the irrigation system where groundwater levels are already high and salinization occurs. To evaluate these changes and possible mitigation measures, two performance indicators that consider groundwater and surface water were used: Relative evapotranspiration and the depleted fraction. Scenario runs revealed that the irrigation water losses from the canals affect the groundwater levels in the downstream part of the irrigated area; an increase in salinity was also revealed.     

River Hydrograph Retransmission Functions of Irrigated Valley Surface Water–Groundwater Interactions

Storage and release functions of western U.S. traditional river valley irrigation systems may counteract early and rapid spring river runoff associated with climate variation. Along the Rio Grande in northern New Mexico, we instrumented a 20-km-long irrigated valley to measure water balance components from 2005 to 2007. Hydrologic processes of the system were incorporated into a system dynamics model to test scenarios of changed water use. Of river water diverted into an earthen irrigation canal system, some was consumed by crop evapotranspiration (7.4%), the rest returned to the river as surface return flow (59.3%) and shallow groundwater return flow that originated as seepage from canals (12.1%) and fields (21.2%). The modeled simulations showed that the coupled surface water irrigation system and shallow aquifer act together to store water underground and then release it to the river, effectively retransmitting river flow until later in the year. Water use conversion to nonirrigation purposes and reduced seepage from canals and fields will likely result in higher spring runoff and lower fall and winter river flow.     

Modified Hazen–Williams and Darcy–Weisbach Equations for Friction and Local Head Losses along Irrigation Laterals

In previous analytical approaches, the direct calculation of friction loss along a lateral is usually based on empirical power-form flow resistance equations, such as the Hazen–Williams and Blasius equations. The more generalized Darcy–Weisbach resistance equation is not usually applied since its friction coefficient varies along the lateral. In this paper, initially, the Darcy–Weisbach and Hazen–Williams equations are systematically compared, leading to a correction form for the Hazen–Williams coefficient. In addition, a more accurate procedure assuming a power function form for the Darcy–Weisbach equation along irrigation laterals is also proposed. The systematic analysis of various typical flow pipe irrigation situations (e.g., sprinkler irrigation laterals of linear or radial-center pivot displacement, trickle irrigation laterals, and manifolds) indicates that the friction loss along laterals calculated using the Darcy–Weisbach equation closely follows a discharge-power form function. The two empirical parameters of the power function depend on the specific pipe characteristics as well as the specific range of discharge values along the lateral. The proposed analytical solution is extended to incorporate the local head loss, the velocity head variation, and the outflow nonuniformity along sprinkler and trickle irrigation laterals. The suggested direct computation solution is demonstrated in two application examples of sprinkler and trickle irrigation laterals and compared with accurate numerical solutions.     

Groundwater Classification Using Multivariate Statistical Methods: Birimian Basin, Ghana

Groundwater from the aquifers of Birimian system in the northern and southern sections of the country was sampled for the concentrations of the major ions in the area. The objective was to determine the spatial groundwater associations which will in turn be used to infer the position of each groundwater group in the flow system. In addition, this study intended to determine the major sources of variation in the hydrochemistry and the suitability of groundwater from aquifers of the Birimian system for irrigation activities. R-mode factor and Q-mode hierarchical cluster analyses were used together with conventional graphical techniques. This study revealed four groundwater associations (clusters) representing three major groundwater types in the Birimian System: the Ca–HCO3 water types which make up Clusters (groups) 1 and 2 members; the Na-K-Cl water types comprising cluster 3 members, and Mg–HCO3 water types comprising Cluster 4 members. Cluster 2 has the lowest average electrical conductivity of 194 mS/m with total dissolved solids (TDS) ranging between 50 and 250 mg/L. This is the freshest groundwater type in the area and is typical of groundwater in recharge areas of the groundwater flow system. Cluster 1 members range in salinity between 50 and 500 mg/L. The highest average salinity is contained in Cluster 3, with TDS in the range of 300 to 1,000 mg/L, which is characteristic of groundwaters in discharge areas of the groundwater flow system. Members of this group are also characterized by high fluoride concentrations; average fluoride concentration in this group is 4.60 mg/L. Cluster 3 is the least desirable of the four clusters, for domestic water supply. Cluster 4 has TDS in the range of 300 and 1,000 mg/L, with low fluoride content. This study finds that the hydrochemistry of groundwater in the terrain is controlled by three major factors: silicate mineral weathering and cation exchange, carbonate mineral weathering, and chemical fertilizers from farms in the area. All the groundwater clusters have low sodium content and will not pose the sodium hazard when used for irrigation. However, as a result of high permeability indices, all but one of the Cluster 2 members plot within the class III region of the Doneen’s chart and are therefore unsuitable for irrigation on these grounds. Clusters 3 and 4 members are the best water types, while Cluster 1 members are equally distributed between Classes II and III categories.     

抚河南昌段水化学特征及影响分析

于2019年12月和2020年6月在抚河南昌段分别采集了地表水样31个和地下水样11个，对水体中的9种离子(K⁺、Ca²⁺、Na⁺、Mg²⁺、Cl^-、SO₄^2-、HCO₃^-、CO₃^2-、NO₃^-)、pH及TDS进行了测定，运用统计分析、Piper三线图、Gibbs图及水质评价进行水化学特征、控制因素及灌溉适宜性分析。结果表明：各离子含量和pH受季节影响明显，枯水期和丰水期阴、阳离子分别以HCO₃^-和Ca²⁺为主；枯水期各离子变异系数较大，空间差异性大于丰水期；水化学类型主要为Ca·Na-HCO₃^-,地表水和地下水之间水力联系密切且转化频繁；水化学控制因素以岩石风化为主，但在丰水期具有向大气降水控制...     

LEPA and Spray Irrigation for Grain Crops

Two low energy precision application (LEPA) sprinkler methods (double-ended socks and bubblers) and two spray sprinkler methods (low-elevation spray application and overhead spray) were used to irrigate corn, grain sorghum, and winter wheat in the Southern High Plains. For full or 100% irrigation, sufficient 25-mm applications were applied to maintain soil water at non-yield-limiting levels determined in earlier research with the three crops. Deficit-irrigated treatments were irrigated on the same days as the control treatment in 25 or 33% increments of the fully irrigated amount. Irrigation water was applied to or above alternate furrows with a three-span lateral move irrigation system. Corn and sorghum were grown on beds and furrows with all furrows diked, and wheat was flat-planted without basin tillage. Grain yields increased significantly with irrigation amount (p ≤ 0.05) for all crops during all years. With full irrigation, grain yields varied little among the sprinkler methods, and yields averaged 13.5, 8.9, and 4.6 Mg∕ha for corn, sorghum, and wheat, respectively. With the 25 and 50% deficit irrigation amounts, sorghum yields with LEPA irrigation were 1.1 Mg∕ha larger than with the two spray methods. For 75% irrigation of sorghum and for deficit irrigation of the other two crops, there was little yield difference between the LEPA and spray sprinkler methods. Grain yields were significantly correlated with seasonal water use with regression coefficients of 2.89, 1.84, and 0.915 kg∕m3 for corn, sorghum, and wheat, respectively.     

Quantifying Rainfall and Flooding Impacts on Groundwater Levels in Irrigation Areas: GIS Approach

Landscapes continuously irrigated without proper drainage for a long period of time frequently experience a rise in water-table levels. Waterlogging and salinization of irrigated areas are immediate impacts of this situation in arid areas, especially when groundwater salinity is high. Flooding and heavy rainfall further recharge groundwater and accelerate these impacts. An understanding of regional groundwater dynamics is required to implement land and water management strategies. The purpose of this study is to quantify the impact of flood and rain events on spatial scales using a geographic information system (GIS). This paper presents a case study of shallow water-table levels and salinity problems in the Wakool irrigation district located in the Murray irrigation area with groundwater average electrical conductivity greater than 25,000?μS/cm. This area has experienced several large flood events during the past several decades. Piezometric data are interpolated to generate a water-table surface for each event by applying the Kriging method of spatial interpolation using the linear variogram model. Spatial and temporal analysis of major flood events over the last four decades is conducted using calculated water-table surfaces to quantify the change in groundwater storage and shallow water-table levels. The drainage impact of a subsurface drainage scheme partially covering the area has also been quantified in this paper. The results show that flooding and local rainfall have a significant impact on shallow groundwater. The study also found that postflood climatic conditions (evaporation and rainfall) play a significant role in the groundwater dynamics of the area. The spatial net average groundwater recharge during the flooding events ranges from 0.19 to 0.52?ML/ha. The GIS-based techniques described in this paper can be used for net recharge estimation in semiarid regions where it is important to quantify net recharge impacts of regional flooding and local rainfall. The spatial visualization of the net recharge in a GIS environment can help prioritize management actions by local communities.     

Method for Measurement of Canopy Interception under Sprinkler Irrigation

A procedure called water wiping is developed to measure the amount of water intercepted by the canopy of winter wheat under sprinkler irrigation. Macromolecule bibulous materials with high water absorption is used to collect sprinkler water intercepted by winter wheat canopy by wiping water from leaves, sheathes, heads, and stems. A procedure is developed for application and verified using field experiments. The results show that this method is rational and applicable. This method could be used to measure canopy interception of other crops with small leaves and short heights.     

Coupled Crop and Solid Set Sprinkler Simulation Model. II: Model Application

In this work, applications of the coupled solid set sprinkler irrigation and crop model AdorSim introduced in the companion paper are presented. The sprinkler irrigation model is based on ballistic theory, while the crop model is based on CropWat. AdorSim was used to evaluate the effect of sprinkler spacing on seasonal irrigation water use (WU) and crop yield. The most relevant results were related to the characterization of advanced irrigation scheduling strategies. The differences in crop yield and WU derived from irrigating at different times of the day were estimated for two locations strongly differing in wind speed. Irrigation guidelines were established in these locations to relate gross water use and water stress induced yield reductions. Simulations were also applied to estimate adequate wind speed thresholds for irrigation operation. In the experimental conditions, thresholds of 2.0–2.5?m?s?1 proved effective to control yield reductions and to minimize WU.     

Experimental Assessment of the Sprinkler Application Rate for Steep Sloping Fields

The Programa para el Manejo del Agua y del Suelo (PROMAS) assists the local farming community in introducing new types of locally available irrigation equipment that are both inexpensive and water efficient. Field experiments enabled determining the maximum application rates that cause zero runoff for slopes above 16% for low-cost sprinkler systems.     

Evaluation of Closed-Loop Site-Specific Irrigation with Wireless Sensor Network

Automated site-specific sprinkler irrigation system can save water and maximize productivity, but implementing automated irrigation is challenging in system integration and decision making. A controllable irrigation system was integrated into a closed-loop control with a distributed wireless in-field sensor network for automated variable-rate irrigation. An experimental field was configured into five soil zones based on soil electrical conductivity. In-field soil water sensors were installed on each zone of the distributed wireless sensor network and remotely monitored by a base station for decision making. The soil water sensors were calibrated with a neutron probe and individually identified for their response ranges at each zone. Irrigation decisions were site-specifically made based on feedback of soil water conditions from distributed in-field sensor stations. Variable-rate water application was remotely controlled by the base station to actuate solenoids to regulate the amount of time an individual group of sprinkler nozzles was irrigating in a 60-s time period. The performance of the system was evaluated with the measurement of water usage and soil water status throughout the growing season. Variable water distribution collected in catch cans highly matched to the rate assigned by computer with r2 = 0.96. User-friendly software provided real-time wireless irrigation control and monitoring during the irrigation operation without interruptions in wireless radio communication.     

Evaluating Regional Solutions to Salinization and Waterlogging in an Irrigated River Valley

Potential solutions to high soil salinity levels and waterlogging problems are investigated on a regional scale using calibrated finite-difference flow and mass transport modeling for a portion of the Lower Arkansas River Valley in Colorado. A total of 38 alternatives incorporating varying degrees of recharge reduction, canal seepage reduction, subsurface drainage installation, and pumping volume increases are modeled over three irrigation seasons (1999–2001). Six performance indicators are used to evaluate the effectiveness of these alternatives in improving agroecological conditions, compared to existing conditions. Predicted average regional decrease in water table elevation (as great as 1.93 m over the irrigation season) is presented for selected alternatives, as well as the spatial mapping of results. Decrease in soil salinity concentration (with regional and seasonal average reduction as high as 950 mg/L) is also predicted and mapped. Estimated groundwater salinity changes, reduction in total salt loading to the river, increase in average regional crop yield, and changes in net water consumption indicate the potential for marked regional-scale enhancements to the irrigation-stream-aquifer system.     

Sprinkler Technologies, Soil Infiltration, and Runoff

Previous simulation studies dealing with surface runoff use mathematical models based on a single soil infiltration relationship to estimate the influence of irrigation application depths and rates on surface runoff depths. Soil infiltration is influenced by such parameters as soil type, tillage practices, and soil water content. Surface runoff data from a field study with a continuous-move irrigation lateral indicate that Green and Ampt soil infiltration parameter values may also be influenced by sprinkler technologies. Soil infiltration parameter values derived from a sprinkler test with a low application rate may produce results that overestimate runoff values for sprinklers with higher application rates. Likewise, parameter values derived from a sprinkler with a high application rate can produce results that underestimate surface runoff for sprinkler technologies with lower application rates.     

Model for the Simulation of Water Flows in Irrigation Districts. I: Description

Significant improvements in the profitability and sustainability of irrigated areas can be obtained by the application of new technologies. In this work, a model for the simulation of water flows in irrigation districts is presented. The model is based on the combination of a number of modules specialized on surface irrigation, open channel distribution networks, crop growth modeling, irrigation decision making, and hydrosaline balances. These modules are executed in parallel, and are connected by a series of variables. The surface irrigation module is based on a numerical hydrodynamic routine solving the Saint Venant equations, including the heterogeneity of soil physical properties. The simulation of water conveyance is performed on the basis of the capacity of the elements of the conveyance network. Crop growth is simulated using a scheme derived from the well-known model CropWat. The irrigation decision making module satisfies water orders considering water stress, yield sensitivity to stress, multiple water sources, and the network capacity. Finally, the hydrosaline module is based on a steady state approach, and provides estimations of the volume and salinity of the irrigation return flows for the whole irrigation season. The application of the model to district irrigation management and modernization studies may be limited by the volume of data required. In a companion paper, the model is calibrated, validated, and applied to a real irrigation district.     

Coupled Surface-Subsurface Flow Model for Improved Basin Irrigation Management

The availability of a process-based coupled surface-subsurface model can lead to improved surface irrigation/fertigation management practices. In this study, a one-dimensional zero-inertia model is coupled with a one-dimensional unsaturated zone water-flow model: HYDRUS-1D. A driver program is used to effect internal iterative coupling of the surface and subsurface flow models. Flow depths calculated using the surface-flow model are used as Dirichlet boundary conditions for the subsurface-flow model, and infiltration amounts calculated by the subsurface model are in turn used in surface-flow mass balance calculations. The model was tested by using field data collected at the University of Arizona, Yuma Mesa, research farm. The maximum mean absolute difference between field-observed and model-predicted advance is 2?min. Applications of the coupled model in improved irrigation management are highlighted. In addition, the significance of the effects of soil moisture redistribution on irrigation water availability to crops and the capability of the coupled model in tracking those changes in soil water status over time are discussed using examples.     

Sprinkler Head Maintenance Effects on Water Application Uniformity

The effects of wear on the ability of hand-move and side-roll sprinkler irrigation systems to maintain the designed water application rate and uniformity are of concern with regards to crop performance, water use efficiency, and environmental impact. Six hand-move and six side-roll sprinkler irrigation systems used under commercial crop production in Lane County, Oreg., were evaluated for equipment wear and performance. Individual sprinkler nozzle size and discharge rates were measured for each system and used in a computer model to estimate field application rate and uniformity. New nozzles were installed on six systems to compare potential application rate and uniformity with existing performance. Despite reducing the coefficient of variation in discharge between sprinklers from 10 to 2%, little increase in water application uniformity was attained. A 13% decrease in mean water application rate was documented after nozzle replacement. Ignored overapplication due to worn or mismatched nozzles results in overirrigation in both rate and total amount, which gives rise to the potential for increased surface redistribution and deep percolation, resulting in water and nutrient losses.     

Coupled Crop and Solid Set Sprinkler Simulation Model. I: Model Development

The development of a coupled crop model (Ador-Crop) and solid set sprinkler irrigation model (Ador-Sprinkler) is reported in this work. The crop model incorporates many of the features developed in the well-known CropWat model. Improvements include the use of thermal time and the input of daily ET0. The solid set sprinkler model applies ballistic theory to determine water distribution resulting from water droplets subjected to a wind vector. Regarding the validation of the coupled model (AdorSim), the plot of soil available water versus measured and simulated yield reduction resulted in similar features. AdorSim explained 25% of the variability in measured yield reduction. Most of the unexplained variability is due to the effect of nonwater-related factors affecting crop yield. In a companion paper, AdorSim is used to investigate optimum water management options in the middle Ebro basin in the NE of Spain.