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A methodology to assess performance of pressurized irrigation distribution networks is presented, which is based on generation of flow configurations from simulated delivery scenarios, and on subsequent analysis of network operation and delivery achievements. The rationale of the methodology entails simulating the peak-demand flow configurations in the pipe network through a deterministic-stochastic combined agro-hydrological model, and forecasting the delivery performance by means of a hydraulic simulation model and of some specific performance indicators. The agro-hydrological model generates disaggregated information on soil water deficits for all the cropped fields downstream from the delivery hydrants, and forecasts the demand flow hydrographs and irrigation deliveries for the entire service area during peak-demand periods. The simulated-demand flow configurations are then passed on to the hydraulic simulation model, which evaluates the hydraulic performance achievable by the pipe network. The performance analysis is then refined using additional indicators specifically adapted to pressurized irrigation networks. The proposed methodology was applied to a large-scale pressurized irrigation system of southern Italy that is in need of modernization. Results proved the usefulness of the combined use of simulation tools as components of an analytical framework to address modernization and re-engineering of existing irrigation delivery networks, on the basis of targeted delivery performance. [ABSTRACT FROM AUTHOR]

This study describes a model named HydroGEN that was conceived for simulating hydrographs of daily volumes and hourly flow rates during peak-demand periods in pressurized irrigation delivery networks with on-demand operation. The model is based on a methodology consisting of deterministic and stochastic components and is composed of a set of input parameters to reproduce the crop irrigation management practices followed by farmers and of computational procedures enabling to simulate the soil water balance and the irrigation events for all cropped fields supplied by each delivery hydrant in a distribution network. The input data include values of weather, crop, and soil parameters, as well as information on irrigation practices followed by local farmers. The resulting model outputs are generated flow hydrographs during the peak-demand period, which allow the subsequent analysis of performance achievable under different delivery scenarios. The model can be applied either for system design or re-design, as well as for analysis of operation and evaluation of performance achievements of on-demand pressurized irrigation delivery networks. Results from application of HydroGEN to a real pressurized irrigation system at different scales are presented in a companion paper (Part II: model applications). [ABSTRACT FROM AUTHOR]

Subsurface drip irrigation (SDI) offers several advantages over alternative irrigation systems when it is designed and installed correctly and when best management practices are adopted. These advantages include the ability to apply water and nutrients directly and efficiently within the crop root zone. Disadvantages of SDI in commercial agriculture relative to alternative irrigation systems include greater capital cost per unit land area (except for small land parcels), unfamiliar management and maintenance protocols that can exacerbate the potential for emitter clogging, the visibility of system attributes (components and design characteristics) and performance, and the susceptibility to damage (i.e., rodents and tillage) of the subsurface driplines. Despite these disadvantages, SDI continues to be adopted in commercial agriculture in the U.S., and research efforts to evaluate and develop SDI systems continue as well. This article summarizes recent progress in research (2010 to 2020) and the status of commercial adoption of SDI, along with a discussion of current challenges and future opportunities. [ABSTRACT FROM AUTHOR]