Figure 28: Groups of variables.
The Bn is structured as an annual balance, subtracting water inputs from the requirements for the different uses. In this manner, it is possible to estimate the available volume for the following HU and the groundwater extracted from the aquifer.
Explaining the meaning of each individual variable would be arduous and descriptions are therefore limited to groups 4 and 5.
Group 4: 'Agricultural consumption'. This group is made up of five subgroups. The combination of these subgroups provides an estimate of the volume of water extracted from HU 08.29 to be consumed by irrigated crops.
Group 5: 'Result variables'. The output volume of the Unit is permitted to be higher than 500 hm3 year-1. This ensures its sustainability and sufficient water for the next unit, under current conditions. Environmental restrictions do not really affect the balance. The volume of water extracted from the aquifer must be lower than 320 hm3 year 1 (PHJ, 1999). These variables are the model outputs.
Once the variables were defined and grouped, a preliminary Bn was constructed using the information collected through questionnaires and data bases (historical series, statistical studies, etc.). Stakeholders' meetings were used to improve and validate the Bn.
The model has been used to evaluate different ways to obtain the sustainability of HU 08.29 (Figure 29).
The model offers the following conclusions (Martin de Santa Olalla et al., 2005):
• Bns support resource managers of the HU 08.29 in the decision-making process. The advantage of this tool is that it can predict the behaviour of the Unit, creating a model when we input one or several variables.
• Specific results offered by the model show, that although the current situation of the aquifer is not sustainable, the substitution of groundwater for the surface water volume established by the PHJ, in addition to proper actions on the part of authorities, can restore aquifer sustainability. It is necessary to increase the volume of replacement up to 115 hm3 year-1 (the current PHJ estimates that 80 hm3 year-1 is the required volume of surface water for reaching sustainability of the aquifer).
This tool shows the direction in which the main efforts should be directed and which should be considered as secondary priorities. Investment in infrastructure should be among the first objectives in order to expeditiously utilize the entire volume of surface water to replace groundwater. Second in priority, would be those efforts directed toward maintaining the price of surface water, improving irrigation efficiency, and the proper implementation of water exploitation plans.
3.3.3 Benchmarking Applied in Irrigation Community Management
In many economic activities, the improvement of management structures, production, etc., are possible via the comparison of different organizations and knowledge of their most effective practices. The objective is to detect the weak and strong points of these organizations, and then integrating changes to improve the management of each of them. In order to accomplish this, different methods exist. One procedure that is well defined is
"Benchmarking", which uses as its main tool, management indicators. The application of this methodology in the management of water resources is very innovative.
To date, there have been many authors who have proposed diverse indicators to measure the efficiency of an irrigation system (Rao, 1993), and applying them to a predetermined zone. However, to find examples of the application of these indicators, in which the efficiency of diverse irrigated land areas can be compared, is less feasible. More and more, management indicators are becoming indispensable tools in the management of irrigated land areas (Molden et al, 2001; van Koppen, 2002; Rodríguez et al, 2004; Malaño et al, 2004; Jayatillake, 2004; Ghazalli, 2004).
The general objective is to obtain a reasonable use of irrigation water, and promoting the sustainability of water resources, however, this can only be achieved by improving the management of water at the level of the user. The completion of the study that began in 2005, intended (Córcoles et al., 2006):
• To apply in 7 irrigation communities the process of "Benchmarking", as a system of comparison and the improvement of irrigation.
• To integrate users in the process of management.
• To expand the indicators of the International Programme for Technology and Research in Irrigation and Drainage (IPTRID) with respect to the service quality rendered to farmers, of the efficiency in productivity, environmental quality, etc., in agreement with the regulatory evolution (European Water Framework Directive 2000/60/CE).
• To analyze how improvement and modernization have augmented irrigation.
• Integration of "Benchmarking" as a tool of the IAS.
In order to carry out the study, it is necessary to collect information of a diverse nature related to the CCRR i.e. general aspects of each organization. From the information collected, a series of indicators are developed, and compiled into 2 groups (description and management).
In addition to these indicators, indicators related to energy efficiency are obtained in the test-sites, as well as the quality of electrical energy supply. This aspect, which has not been thoroughly studied before, permits an understanding of energy efficiency. It also allows for the proposal of different improvement solutions, from the comparison of results between the different irrigated land areas.
Initially, contact with managers of each of the irrigation community was made. This was done, in an effort to explain the project and to make an introductory exposition of the methodology of application, emphasizing necessary information in order to carry out the objectives presented. There has been a marked increase in the interest shown by irrigators to participate in the project.
Next, began the collection of required information for quantifying the descriptive indicators of the test-site. This information has been utilized to characterize the zones of study. Of the proposed descriptive indicators, the greatest difficulty was to obtain the cropping pattern and checking the existing systems of irrigation in the different zones. This information, obtained from field work and interviews with the staff of each irrigation community, was integrated into a Geographical Information System (GIS).
With the active participation of an optimum and diverse number of farmers, the completion of 21 evaluations of the irrigation systems in the different zones were completed, as well as, a survey of the implementation of irrigation recommendations made by the SAR (Montoro et al, 2004).
In this manner, it has been possible to understand the farmwork performed by a representative group of farmers in the zone, mainly the water applied, as well as knowledge of the yields and average market prices of the most representative crops of each zone.
The conclusions of the 2006 season are as follows:
• The initial results show elevated interest by managers of the irrigable areas in the application of this methodology, principally in the improvement obtained via energy indicators.
• The degree of participation of technicians and farmers has been satisfactory, with initial positive involvement that has remained throughout the entire season.
In this moment, the 2007 season is finishing. 3.4 Other Lines of Research
3.4.1 Agroclimatic Characterization and Water Consumption of Castilla-La Mancha
In the irrigable areas of CLM, the water available for irrigation is limited. Under these conditions, a valuable tool is the power to quantify, by zones, the water consumption of the crops, for farm management.
In order to obtain an understanding of water consumption, by means of empirical methods, it is necessary to know the values of crop Evapotranspiration (ETc) by multiplying the reference evapotranspiration (ETo) by the Kc (FAO Methodology) (Allen et al, 1998). Depending on the method used, the ETo estimation requires diverse climatic variables that are usually not registered in the agronomic scope (Jensen et al, 1997).
When a limited amount of data and number of climatic stations are available, it is necessary to estimate, and to represent spatially, the values of different variables for those zones in which data are not provided. It can be accomplished via various technical procedures such as: geostatistics, use of neuronal networks, Cluster analysis, etc.
However, when working with natural phenomena it is necessary to know the influence of the position of the sample in space and/or time. Thus, the geostatistics have as an objective the characterization of the space and/or temporal dispersion of the natural phenomena, to be able to model the natural resources and to operate them in a reasonable manner (Jiménez et al, 1993). Geostatistics are a technique used in the analysis of the spatial variability of climatic data, and are supported by numerous studies (Delhomme, 1978; Davis, 1986; Hashmi et al, 1994).
The main objective of this work is to create a climatic characterization of CLM, considering primarily the specific climatic variables utilized in irrigation. The specific objectives are as follows: To analyze and represent the spatial and temporal variability of the climatic variables that defines local climates (temperature, precipitation, etc.); To analyze and represent the spatial and temporal variability of the evaporative demand of the atmosphere
(ETP, ETo); Spatial and temporal distribution of the precipitation deficit; Obtaining the spatial and temporal distribution of the crop water requirements.
In order to achieve these objectives it is necessary to perform the following tasks:
• Inventory and collection of climatic data of the primary (only temperature and precipitation data) and complete stations of the region. The inventory of the primary stations (110) and complete stations (5) has been performed. The complete stations facilitate more precise information, but are very few in number. The primary stations are sufficient in number, but the data is less reliable. It is necessary to compile the available data, to analyze it and edit it, with the objective of obtaining homogenous series of 20 years (1981-2000). Only 10 stations have the complete 20 year series of data, in the stations lacking the necessary data augmentation techniques have been applied, such as: artificial neuronal networks (Nabney, 2001).
• The division of CLM into distinct zones according to various criteria. This section attempts to classify the stations via a climatic point of view and to distinguish zones with different characteristics.
• Classification of the soils and distribution of the most important crops of CLM. Utilizing the available information and existing maps, the digitalization of such resources will be done in order to combine the information with the main climatic parameters. In addition, a compilation of the available information (MAP, JCCM, INE, etc.) regarding the most important crops and their geographical distribution will be performed.
• Estimation, by different methods of the potential and reference evapotranspiration. It is necessary to perform a thorough reference review of the different methods utilized in the determination of the ETo, with the purpose of determining which one best complies with the available climatic parameters. The alternative empirical methods, which are of easy applicability, will also be calculated (Hargreaves, Thornthwaite, Blaney Criddle, Turc, etc.).
• Application of geostatistics for the representation of the spatial variability of the studied climatic variables (GEO-EAS, GEOPACK). A reference review of geostatistics as a technique for the analysis of the spatial variability of climatic data will be performed. The election and application of the suitable techniques for the construction of maps that attain isolines for temperature, precipitation, evaporative demand, precipitation deficit, crop water requirements (mainly maize, garlic, alfalfa, grapevine, and olive trees, among others) and water balance, will be performed.
3.4.2 Improvement of Energy Efficiency in Irrigated Land Operations
In Spain, agricultural activities constitute 3% of total energy consumption. However, in the province of Albacete, where the most significant crops have high water requirements, and water is pumped from very deep wells, the rate of energy consumption is higher (17.4%).
In terms of irrigation, the regional government of CLM has focused its attention on the implementation of collective on-demand irrigation networks. These irrigation infrastructures insure efficient water use, reduce farmers' disputes and diminish the problems created by improper use of irrigation water.
Further studies are required to facilitate decision-making regarding the improvement of both water use and energy efficiency. A hydraulic and energy analysis of on-demand irrigation networks permits the obtainment of general results. With this objective, the following is proposed:
• An analysis of the mode in which farmers are managing and using water in the area studied.
• An analysis of the traditional prediction models of discharge flow in on-demand irrigation networks and a validation of the new models proposed through network measurements.
• The development of a hydraulic model of the network and its calibration, as a basic tool in improving the network operation and its management.
• Modelling of the pumping stations, and allowing an energy efficiency increase through regulation improvements.
• The development of a methodology able to define pressure and discharge more accurately.
• A study of the effect of energy supply quality and network harmonics generation, showing the problems this kind of disruptions lead to.
In order to administer this study, two on-demand irrigation networks have been analyzed (Sector I and Sector II), which form part of the "Sociedad Agraria de Transformación SOciedad de REgantes de TArazona" (SAT SORETA), located in Tarazona de La Mancha (Albacete). Sector I irrigates 550.2 ha and Sector II 494.1 ha. Water is obtained from the HU 08.29. Sprinkler irrigation is the most commonly used irrigation system when irrigating plots. However, it should be mentioned that drip irrigation systems are also utilized.
The hydraulic analysis of the irrigation network has been performed by obtaining accurate pressure and discharge measurements. In this case, the discharge data collecting system of the network has been utilized. Moreover, an ultrasonic flowmeter has been used to measure the head discharge. Pressure has been measured with pressure transducers, which have been located strategically along the two irrigation networks studied. The energy analysis has been carried out by using three electrical network analysers, which were installed at the Sector I pumping station. In addition, a series of technical visits were made in order to determine the cropping pattern and check the network topology.
The study related to water use and its management was completed by using "benchmarking" techniques, in collaboration with farmers.
Flow rates have been measured, so that the traditional methods to estimate water flow rate in each line can be validated. Furthermore, the new stochastic method proposed, based on the Daily Random Demand Curves, has been validated. Figure 30 shows the validation of the new proposed methodology and its comparison with the Clément methodology.
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