In order to take advantage of pressurized irrigation, drip irrigation is being introduced in extensive crops formerly irrigated by surface or sprinkler irrigation, searching for reduce the pressure requirements as low as possible, and therefore the energy cost if pumping is involved. Turbulent emitters (with pressure dependent emission) rather than self compensating drippers are frequently found in these applications to minimize the coverture cost. Small farmers with low income trends also to use turbulent emitters for the same economical reason. Often, if they live in mountainous areas, they have adopted drip irrigation techniques because is the most suitable alternative in highly stepped plots.

 In these two conditions, and some others, the proper hydraulic design is critical. Advance, but seamless to use, design methods and tools are required. They must really consider the local emitter pressure-dependent flow rate, in presence of quite irregular plots with uneven altitudes and working at the lowest pressure limits. Not much intuitive and affordable design tools exist for these purpose, where accurate modelling is mandatory. GESTAR platform, an integrated software for irrigation hydraulics design and management, has recently incorporated the necessary resources for this purposes.

GESTAR, (www.gestarcad.com), a code in continuous developing at Universidad de Zaragoza (Spain) since 1995 under the auspices of the Aragon Regional Government, offers a complete software package for engineering of pressurised irrigation systems (collective distribution networks and systems for use in irrigation on plots). Its tools and modules, specifically designed for pressurised irrigation and tested over the long term, enable optimum design, execution and management, integrating a wide range of resources, many of them available exclusively in this programme, and a long history of innovations and application to large and small systems. The main performances of GESTAR´s new drip irrigation module are presented in the contribution and compared with traditional “Christiansen rule type” calculation criteria, with emphasis in the capability to predict hydraulic performances in simple or complex conditions. The sizing of components and hydraulic and energy analysis, uses specialized numerical engines for optimum sizing and simulation, obtaining economical designs and reliable predictions of all hydraulic parameters, even in plots with very irregular plans and topography. The hydraulic modelling of individual or distributed emitters, with emitted flow rate depending on pressure gives precise, provide interactive and context-sensitive results, gives answer to the above mentioned challenges searching for low cost and low pressure drip irrigation