Water Management In Irrigated Agriculture Research Articles

Efficient Irrigation of Maize Through Soil Moisture Monitoring and Modeling

Agriculture is the major user of water resources, accounting for 70% of global freshwater demand. As the demand for clean water increases, so does the need to implement more efficient strategies for water management in irrigated agriculture. While the benefits of precision irrigation in high-value crops, such as cannabis, tomatoes, and potatoes, are fully recognized, there is still need to investigate and implement cheap and efficient irrigation strategies for widespread low-value crops such as maize. In this study, the soil moisture dynamics in a sprinkler-irrigated maize field in Veneto (Northeastern Italy) was monitored using six time domain reflectometry (TDR) probes for the entire growing season. The TDR sensors were positioned at different depths into two separate sites: an Uninformed Site irrigated based on the farmer's experience and an Informed Site in which a water balance irrigation strategy was applied based on soil moisture measurements. A parsimonious hydrological model was then implemented and calibrated to quantify the different water balance terms (precipitation, evapotranspiration, lateral fluxes, and deep percolation). The comparison between the water budget terms in the two sites highlights that soil moisture monitoring during agriculture activities leads to substantial savings in terms of irrigation water volumes requirements and cost, without compromising the productivity of the crop field. A simplified upscaling of the results at the regional scale, assuming average conditions as in this study site and growing season, reveals that potentially significant economic savings, compared to the total profits linked to maize crops, could be possible.

WATER EFFICIENCY INDICATORS FOR EVALUATION OF INSTITUTIONAL TRANSFORMATIONS IN IRRIGATION MANAGEMENT

The modern problems of irrigation sector and need of its reforms are presented as well as the importance of evaluation of reforms results via system of indicators that characterized efficiency of water use and effectiveness of water management. For this purpose, the methods of system analysis are used and the main economic and ecological factors influencing the efficiency of water use are determined. Based on the results of the system analysis an indicative assessment proposed for the following three spatial levels: for assessment of the efficiency of the irrigation sector at the national level; evaluation of water management efficiency at the level of main infrastructure and; at the level of non-state irrigation network. The efficiency of water use in irrigated agriculture at the national level is calculated as the added value in agriculture sector related to the amount of water taken for agricultural purpose. This indicator shows general productivity of water use in irrigated agriculture. Groups of ecological and economic indicators that proposed for assessing the efficiency of water use on the level of the main irrigation infrastructure allow to assess the quality of irrigation service under existing management model. For evaluation of efficiency of water use and management at the level of water users’ organizations and individual farms the following economic indicators are selected: land productivity; water productivity; irrigation area; volume of water used for irrigation; costs of irrigation and amount of production. The soil fertility and ecological state of the irrigated lands proposed as a main ecological indicator. In addition to the economic and ecological indicators the number of organizational and technological factors that provides reliability of water supply to the fields and show a effectiveness of water management should be evaluated also. The proposed integrated system of indicators can be used to evaluate the state of water use and water management in irrigated agriculture, as well as to assess the results of institutional reforms of the sector that approved by the state strategic documents.

ORGANIZATIONAL AND ECONOMIC MECHANISM OF IMPROVING THE EFFICIENCY OF WATER RESOURCE MANAGEMENT

The necessity of a fundamentally new approach to the formation of a water management system and state regulation of water use has been proved in order to achieve sustainable water use parameters in the agricultural sector of the economy. The principles of integrated water management in irrigated agriculture are defined. It is shown that the formation of the model of integrated management in the water management and reclamation complex requires the introduction of organizational and economic innovations, changes in the institutional environment, transformations in the organizational structure of agricultural enterprises and public authorities. The essence of transformations of the irrigated agriculture management system is disclosed, which involves the transfer of irrigation systems management from state structures to non-governmental organizations. In this case, the transfer of powers and responsibilities from state structures to non-governmental organizations can be carried out with the transition stage of joint management, which is the most rational in the current conditions. Found that the formation of effective management system is impossible without institutionalization of a wide spectrum of forms of partnership relations between different objects of functioning. It is shown that the reforming of irrigation systems management should be carried out on the basis of decentralization with the transfer of water management and water operations to water, this will ensure that water resources and irrigation system infrastructure are managed effectively at the lowest level. The basic directions of improvement of the economic mechanism of development of reclamation are offered.

EFFECT OF SAMPLE RE-SATURATION ON SOIL-WATER CHARACTERISTIC CURVE

ABSTRACT Soil-water characteristic curve (SWCC) is an important tool for water management in irrigated agriculture. However, factors such as texture and structure of soils influence SWCC behavior. According to the literature, wetting and drying cycles alter SWCC. A similar process of re-saturation and drying occurs during SWCC obtainment under laboratory conditions. Based on the hypothesis that re-saturation process alters SWCC due to clay loss in the sample, this study aimed to obtain the SWCC, S index, and pore size distribution from samples submitted to re-saturation cycles, as well as from not re-saturated samples but under higher matric potentials (-2, -4, -6, -8, and -10 kPa). For this, disturbed and undisturbed soil samples, collected from the A (sandy texture) and Btg (sandy clay loam texture) horizons of a Argissolo Acizentado, were used. After obtaining SWCC, each air-dried soil sample was submitted to particle size and clay dispersed in water analyses to verify whether the soil lost clay. The experimental design was a completely randomized design with two methods of SWCC constructing (with and without re-saturation) and eight replications. The re-saturation process generates a loss of clay in the sample, not causing significant changes in SWCC considering the assessed textural soil classes. In addition, sandy soil samples are more sensitive to changes in pore size distribution when submitted to re-saturation.

Satellite-based ET estimation using Landsat 8 images and SEBAL model

Estimation of evapotranspiration is a key factor to achieve sustainable water management in irrigated agriculture because it represents water use of crops. Satellite-based estimations provide advantages compared to direct methods as lysimeters especially when the objective is to calculate evapotranspiration at a regional scale. The present study aimed to estimate the actual evapotranspiration (ET) at a regional scale, using Landsat 8 - OLI/TIRS images and complementary data collected from a weather station. SEBAL model was used in South-West Parana, region composed of irrigated and dry agricultural areas, native vegetation and urban areas. Five Landsat 8 images, row 223 and path 78, DOY 336/2013, 19/2014, 35/2014, 131/2014 and 195/2014 were used, from which ET at daily scale was estimated as a residual of the surface energy balance to produce ET maps. The steps for obtain ET using SEBAL include radiometric calibration, calculation of the reflectance, surface albedo, vegetation indexes (NDVI, SAVI and LAI) and emissivity. These parameters were obtained based on the reflective bands of the orbital sensor with temperature surface estimated from thermal band. The estimated ET values in agricultural areas, native vegetation and urban areas using SEBAL algorithm were compatible with those shown in the literature and ET errors between the ET estimates from SEBAL model and Penman Monteith FAO 56 equation were less than or equal to 1.00 mm day-1.

Water availability to soybean crop as a function of the least limiting water range and evapotranspiration1

ABSTRACT Irrigation management aimed at optimal production has been based only on the water factor. However, in addition to the water potential of the soil, factors such as soil penetration resistance and soil O2 diffusion rate also affect plant growth and interfere with water absorption, even if moisture is within the available water range. This study aimed at quantifying the least limiting water range and demonstrating its potential in soil and water management in irrigated agriculture. In order to determine the least limiting water range, soil water retention curves and soil resistance to penetration were determined from undisturbed soil samples. The sequential water balance and the reference, crop and real evapotranspiration were determined for a soybean crop season. Soil aeration was the least limiting water range upper limit for soils with bulk density greater than 1.33 Mg m-3, whereas soil resistance to penetration was the lower limit for bulk density higher than 1.43 Mg m-3. The bulk density of the soil studied was 1.35 Mg m-3, indicating 0.37 m3 m-3 of water availability, based on the least limiting water range, which is sufficient to supply the crop evapotranspiration. Irrigation management based on the least limiting water range is more efficient and complete than that based only on available water.

Knowledge, participation and transparency in groundwater management

Water in sufficient amounts and quality is essential for meeting both human and ecological needs. Most water used by mankind is destined for agriculture, and demand is steadily growing. Under this pressure, water management faces significant environmental problems. In the case of groundwater, these difficulties are exacerbated by intensive, unregulated exploitation, and the spatial distribution of wells. Challenges to current water management therefore encompass multiple levels (environmental, technological, social, economic, and political), and their solution requires focus and a range of spatial and temporal scales to ensure integrated water resource management. Knowledge, participation and transparency are all crucial to help in conflict prevention and resolution. New challenges require new technologies that can help to resolve them. This paper analyses how the coordinated use of new technologies provides important results to support decision-making in planning and water management in irrigated agriculture. This case study is especially applicable to groundwater management in large areas where conventional planning, monitoring and control methods are extremely expensive and imprecise. The specific case of the Mancha Oriental Aquifer (SE Spain) is examined as it is an area where such conventional methods have proven to be inadequate.

Optimization of cropping pattern using goal programming approach

Irrigation planning and scheduling are essential components of water management in irrigated agriculture. For this purpose, optimal use of land and water is required for optimization of cropping pattern under a set of limitations. Number of approaches like benefit-cost, functional, programming, and simulation are commonly used for optimization of cropping pattern. The paper presents three different cropping plans of goal programming (GP) approach, which was considered for maximization of net return, protein and calorie values with minimum land and water for Barna command area. The factors like amount of net return, utilization of surface and ground water by different plans were considered for the selection of best cropping plan of GP for optimization of cropping pattern for the command area under study. The paper gives the methodology adopted in optimizing the cropping pattern using GP approach and the results obtained from the study.

Optimization of multi-objective cropping pattern using linear and goal programming approaches

Irrigation planning and scheduling are essential components of water management in irrigated agriculture. For this purpose, optimal allocation of land and water is required for optimization of cropping pattern under a set of limitations. In this paper, an attempt was made to optimize the cropping pattern for Barna irrigation project using Linear and Goal Programming (LP and GP) approaches. Three different objectives such as maximization of net return, protein and calorie values were considered for optimization of cropping pattern. The factors like amount of net return, values of protein and calorie, and quantum of water utilized for irrigation by LP and GP were considered for selection of best approach for optimization of cropping pattern for the project. The paper presents the methodology adopted in optimizing the cropping pattern using LP and GP approaches and the results obtained from the study. GP approach was found to be best for optimization of cropping pattern for the project.

Sustainable conjunctive water management in irrigated agriculture: Model formulation and application to the Yaqui Valley, Mexico

This paper investigates strategies to alleviate the effects of droughts on the profitability and sustainability of irrigated agriculture. These strategies include conjunctive management of surface water and groundwater resources, and engineered improvements such as lining of irrigation canals and addition of regional pumping well capacity. A spatially distributed simulation‐optimization model was developed for an irrigated system consisting of multiple surface water reservoirs and an alluvial aquifer. The simulation model consists of an agronomic component and simulators describing the hydrologic system. The physical models account for storage and flow through the reservoirs, routing through the irrigation canals, and regional groundwater flow. The agronomic model describes crop productivity as a function of irrigation quantity and salinity, and determines agricultural profit. A profit maximization problem was formulated and solved using large‐scale constrained gradient‐based optimization. The model was applied to a real‐world conjunctive surface water/groundwater management problem in the Yaqui Valley, an irrigated agricultural region in Sonora, Mexico. The model reproduces recorded reductions in agricultural production during a historical drought. These reductions were caused by a decline in surface water availability and limited installed pumping capacity. Results indicate that the impact of the historical 8‐year drought could have been significantly reduced without affecting profit in wet years by better managing surface water and groundwater resources. Namely, groundwater could have been more heavily relied upon and surface water allocation capped at a sustainable level as an operating rule. Lining the irrigation canals would have resulted in water savings of 30% of historical reservoir releases during wet years, which could have been used in subsequent drier years to increase agricultural production. The benefits of a greater reliance on groundwater pumping by installing additional wells are limited due to pumping restrictions near the coast to avoid seawater intrusion and due to increased pumping costs.

Controlled drainage for improved water management in arid regions irrigated agriculture

In arid regions, controlled drainage is the next logical step towards improving water management in irrigated agriculture and reducing the environmental impacts of subsurface drainage flow. Controlled drainage has been practiced in humid areas for a long time. In this paper traditional subsurface drainage system design procedures are described, followed by alternative design criteria for arid regions and suggestions for system design to include control structures that enable better drain system management. The suggested changes include reducing the installation depth of laterals, accounting for crop water use from shallow ground water in the design, and relaxing the mid-point water depth requirement. Active control of drainage systems in arid irrigated regions is a developing concept that is currently being evaluated around the world. Research in the U.S. and Australia has demonstrated that water tables in irrigated areas can be effectively controlled with various types of structures. Control has resulted in reduced volumes of drainage water and total salt loads discharged. Salt accumulation in the root zone is a consideration in adopting controlled drainage, but other research has demonstrated that it is possible to manage salt accumulation through careful water management.

Lessons learned from the change from supply to demand water management in irrigated agriculture: a case study from Pakistan

Scarcity of good quality water has led many countries to introduce demand-based water management in the irrigated agriculture section in place of the existing supply-based water management. This transition requires institutional changes, including the formation of Water User Associations (WUAs). The paper reviews the constraints of irrigated agriculture in Pakistan and discusses the conditions for success in the formation of farmers’ organizations. This paper seeks to show that the development of WUAs is a vital step in the development of integrated water resource management. It is argued that IWRM is a prerequisite for a sustainable society in water-dependent countries that are increasingly water-scarce—like the paternalistic and bureaucratic societies of South Asia.

Crop ecology: productivity and management in agricultural systems

Preface Part I. Farming Systems and Their Biological Components: 1. Agricultural systems 2. Trophic chains 3. Community concepts 4. Genetic resources 5. Development Part II. Physical and Chemical Environments: 6. Aerial environment 7. Soil resources Part III. Production Processes: 8. Nitrogen processes 9. Water relations 10. Photosynthesis 11. Respiration and partitioning Part IV. Resource Management: 12. Soil management 13. Strategies and tactics for rainfed agriculture 14. Water management in irrigated agriculture 15. Energy and labor Part V. Farming, Then, Now and in the Future: 16. Evolution of wheat farming systems in southern Australia 17. Technological change in high-yield agriculture 18. The future of agriculture Species list Conversions and constants useful in crop ecology Index.

Rectangular Measuring Flumes for Lined and Earthen Channels

Good water management in irrigated agriculture requires that irrigation water be accurately measured. Presented herein are design procedures and rating tables for modified broad‐crested weirs (which act hydraulically as long‐throated flumes) that have rectangular control sections. The ratings are presented in terms of discharge per unit width so that rectangular broad‐crested weirs of a variety of sizes can be used. This makes it easier for the designer to adapt the flume to the site rather than vice versa. These weirs or flumes can be placed in lined and unlined canals of any shape. The rating tables are presented for rectangular lined canals with given values of sill or crest height. An adjustment procedure is given to develop rating tables for other approach area and sill height combinations. The head loss across the weir required to maintain a unique head discharge relationship is also presented. Finally, a design example is given for a rectangular lined canal. With this information, a rectangular measuring flume can be designed for a wide variety of site conditions.