Summary
  The new challenges proposed by the Water Framework Directive in Europe mean a deep change in all levels of irrigation water management, where cost recovery is imposed as a measure for efficient water use and environmental sustainability of the activity.
  The construction of new infrastructures to improve the overall efficiency of irrigation must be accompanied by proper management; otherwise large investments undertaken are not justified. The agronomic management and hydraulic of irrigation pressurised networks leads to the satisfaction of the water crops requirements in the most efficient way, adjusting the volumes supplied to the needs. Due to the pressurized irrigation requests the input of energy, the ideal way is performing irrigation using the least amount of energy possible. Finally, if it is practised collective fertigation, it is desirable to know the fertilizer requirements of crops, to meet adequately the scheduling of the irrigation fertigation.
  In order to optimize the use of all inputs involved in irrigation, water, energy and fertilizers, it is necessary to keep track of all the processes that are involved, in order to detect weaknesses in management and improve them. Given the large amount of information required to do so, it is advisable to develop a Decision Support System (DSS), which feeds the processes with different alternatives, and assessing the results in each case. Since most of the information used is spatial, Geographic Information Systems (GIS) are shown as the best working tool for this purpose.
  At work developed is described the methodology followed for the development of a DSS-oriented to manage pressurised irrigation networks, called HuraGIS (Tools for Rational Use of Water with the support of a GIS). It has been implemented tools capable of simulating all processes involved in agronomic management and hydraulic. At the same time it is possible to generate new management scenarios, allowing each to calculate a set of indicators to assess each scenario.
  For that purpose a relational database model has been designed, linked at the same time with spatial information. For its implementation, a series of modules have been developed that allow the capture, editing and debugging of data. Other modules allow HuraGIS simulating all agronomic irrigation processes. In addition, in order to reproduce the hydraulic processes has been integrated EPANET, a program widely spread to perform extended period simulations of hydraulic behaviour and water quality in pressurized networks. Finally, as optimization tools have been incorporated linear programming libraries and optimization heuristics, such as genetic algorithms.
  The methodology has been applied to a study case, the Water Users Association of Senyera (Valencia, Spain). The required datafield were collected and implemented in HuraGIS. In a first phase, a diagnosis on the management carried out during the irrigation season 2006 took place, by calculating a series of indicators reflecting the application efficiency of irrigation water, distribution of fertilizers by the network, energy consumption and economic cost. As a result there was an overall water application efficiency of 92.2%. At intake level the average efficiency was 97.74%, but with a standard deviation of 45.59%, which came to confirm the need to manage networks also at the level of irrigation subunit.
  It was subsequently made use of optimization tools to simulate new scenarios, to study possible improvements in management. Firstly the hydraulic network was modelled and calibrated by means of field measures. The analysis of new scenarios came to show the potential of the combination of GIS, hydraulic models and optimization tools to obtain significant energy savings and for improving fertilizers distribution. The reduction of energy consumption ranged between 36.04% and 15.32%, and reduced the associated costs between 64,17% and 43,41%, depending on the grouping intakes in irrigation sectors and other kinds of practical constraints. Also, the application of fertilizer could be improved in a 6.73% on average, measured in terms of efficiency in the distribution of fertilizer. The development of a real case came to demonstrate that the results are conditioned by the strategies adopted by managers, and also by the demands of users that limit possible strategies. Even so, savings can be considerable.
  In conclusion can be said that how best to proceed to improve the water application efficiency in an overall way is to set irrigation scheduling to the strictly necessary. Moreover, if efficiency has to be improved at intake level there are two ways to proceed: either by changing the flow of subunits to standardize the times of irrigation, or adjusting the irrigation time of each intake to the theoretical, assuming that the automation system and Control Unit allows it. With regard to energy saving, often based on improving the working conditions of pumping equipment, often conditioned by the flow demand, which can be adjusted by an adequate sectorization of the network. Finally, the distribution of fertilizers can be improved through proper rotation of different irrigation sectors in different turns.
  Keywords: irrigation management, irrigation modernization, irrigation networks, drip irrigation, pressurised irrigation, water users association, collective fertigation, Geographic Information System, hydraulics simulation, optimization, energetic saving, genetic algorithms, EPANET.