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.

Introduction

Given the expected population growth on Earth from the current 7 billion to 9.2 billion by the year 2050 (United Nations, 2007), there are major concerns in various parts of the world about the access of future generations to water in sufficient quantity and quality for subsistence food production. In the coming decades, humanity will face significant challenges not only to meet these basic needs, but also to ensure the sustainability of existing water uses and ecosystems (Oki & Kanae, 2006; Gerbens-Leenes et al., 2009).

As pointed out by Esteban & Albiac (2011), water degradation is widespread in many river basins worldwide due to increasing anthropogenic impacts. This problem is exacerbated in the case of river basins in arid and semi-arid climates, where water management is complicated because demand is usually higher than the resources available. All these aspects mean freshwater is an increasingly valuable, scarce resource (Llamas & Martínez-Santos 2005; López-Gunn et al., 2012).

In regions heavily affected by current droughts (e.g. the midwestern USA (California's Central Valley and High Plain Aquifer), western Mexico in north America, South Australia, northern Saudi Arabia and Iran in Asia, the upper Ganges in India and Pakistan, the northern China Plain, and southern Europe (aquifers in southern Spain and Italy)), agriculture accounts for over 80% of total groundwater withdrawals (Custodio, 2002; Gleeson et al., 2012). Over the past century, the emergence of technology such as drilling and submersible pumps has allowed individuals to transform large areas into irrigated croplands. In some parts of the world, individuals did not need permits in order to drill wells, and therefore the use of groundwater can be uncontrolled and unregulated. In fact, this situation of intensive groundwater use has been called by some a ‘silent revolution’: ‘A revolution because it is producing significant social and economic impacts. It is silent because it has been made without noise, without fanfare. Its principal authors were millions of individual farmers in the most arid and semi-arid regions of the world where millions of wells have been drilled’ (Llamas & Martínez-Santos 2005).

One of the most notable cases may be India, where economic development over the past 40 years has been due largely to the irrigation of over 400,000 km2 of land using groundwater, primarily funded by individuals or small municipalities (Shah, 2005). Unfortunately, this intensive groundwater exploitation has created new problems, such as decreases in groundwater levels, the disconnection of rivers and wetlands from aquifers, aquifer pollution, and other related management problems such as the monitoring and organization of irrigated areas (World Bank, 2010). A recent communication from the European Union to the EU parliament, the Blueprint to Safeguard Europe's Water Resources (COM/2012/673), identifies the over-abstraction of water, in particular for agricultural use, as the second most common pressure on the ecological status of EU water (in 16 member states).

This situation also impacts the long-term negative perspective of atmospheric prediction models on climate change: (a) average global temperatures will increase by approximately 5 °C by the year 2100 (this will mean increased evapotranspiration (ET) in crops and therefore increased irrigation needs), and (b) a decrease in rainfall (only in certain areas of the planet), increased droughts, floods, and desertification could be accentuated in areas that are already climatically variable (US EPA, 2010).

In this scenario, water management in irrigated agriculture faces new challenges in different areas, sectors, and scales, which are compounded in the case of intensive groundwater use, where the principles of classic regulating reservoirs and channels are not applicable. Indeed, most difficulties and mismanagement are mainly due to the attempted application of management tools based exclusively on surface water models. Traditional surface water management systems are difficult to integrate in the model of groundwater spatial distribution due to its own characteristics (large surface area, high number of pumping wells without flow meters, etc.). A new management model is necessary that will take into account the reality that, in these areas of the world, drought impacts first affect surface water, which represents, at best, about 20% of the available resources (Siebert et al., 2010), and as a result, it will put severe pressure on the groundwater resource affecting groundwater availability.

In addition to the scarcity of the resource and its management, groundwater spatial distribution is one of the elements of greatest conflict among territories. Although, theoretically, it could be structured by topographic boundaries, groundwater does not generally coincide with these limits. Irrigation schemes, watersheds, and groundwater bodies are different management areas that correspond to distinct spatial scales and to different users and administrative areas. Therefore, the spatial scale or, more specifically, the definition of the system and the degree of aggregation chosen are critical to the interpretation of water use and productivity.

Challenges for current water management occur at multiple scopes, therefore, the answers should also be diversified in area and spatial and temporal scales. To adequately respond to the new challenges, new technologies should include: (a) remote sensing, (b) geographic information systems (GIS), (c) mathematical modelling of hydrogeological systems, and (d) information and communications technology (ICT). Taken together, these tools can generate updated information for transmission at different spatial and temporal scales. We explain each of these technologies in turn.

As pointed out by Calera et al. (2005) and Castaño et al. (2010) regular images from Earth observation satellites are adequate for monitoring land cover since the use of irrigation water has an immediate result on the appearance of different vegetation covers. The analysis of digital satellite images allows the monitoring of ET, and as a result of such monitoring we can establish: (a) the optimal amount of water to be applied (irrigation), and (b) the water budget in the soil, by combining satellite information with data provided by agro-meteorological stations. This information can be shared by several stakeholders and verified using GIS tools. Via GIS, the evolution of land cover can be compared with the hydrogeological and administrative reality (land register or cadastre), thus linking management databases with fieldwork information.

The modelling of groundwater flow in aquifers and of its relationship with surface ecosystems is in line with the type of methodology proposed by the Water Framework Directive to define a groundwater management programme (Vàzquez-Suñé et al., 2006). In fact, modelling is generally one of the best ways to manage, integrate, validate, and quantify the hydrogeological information collected with remote sensing techniques and GIS. A key to the adequate planning and management of water resources is to have sufficient knowledge of the impacts that groundwater has on associated ecosystems and then to make predictions of the hydrogeological behaviour of an aquifer system under different operating scenarios.

Finally, ICT allows real-time access and sharing of all information regardless of its complexity. Its use can put that information and data needed for water management in agricultural parcels, irrigation systems and aquifers, in the hands of farmers and managers almost instantly, covering thousands of properties, and square kilometres (see Calera et al., 2005; Osann Jochum et al., 2006).

A series of conclusions and examples of the abilities of these new technologies is presented in this paper, pointing out elements that could help in both planning, management and improvement in efficiency of water use in sustainable agricultural irrigation. They are the result of over a decade of combined experience between researchers (Regional Development Institute of the University of Castilla–La Mancha, IDR-UCLM) and farmers and stakeholders of the Mancha Oriental Aquifer (JCRMO due to the Spanish acronym for Junta Central de Regantes de la Mancha Oriental), the regional government of Castilla–La Mancha (JCCM, Junta de Comunidades de Castilla–La Mancha), and the Júcar River Basin administrative district (CHJ, Confederación Hidrográfica del Júcar) in the implementation and development of new tools for water management in one of the largest aquifers in southern Europe (the Mancha Oriental Aquifer (MOA) in the Júcar Basin, Spain) (Figure 1). The CHJ's most relevant task is to administer the different aspects of planning and management based on participation and transparency to enable the cooperation of the various stakeholders involved.
Fig. 1.

Location of MOA. JRB: Júcar River basin; MOA: Mancha Oriental Aquifer.

Fig. 1.

Location of MOA. JRB: Júcar River basin; MOA: Mancha Oriental Aquifer.

Participation requires that the government, stakeholders, and other social actors share correct and updated information about irrigated areas, water sources, and the hydrogeological behaviour of aquifers and associated surface ecosystems. The information should be seen as community credible and defensible by scientists and water managers. Once all sectors affected by water management share the same information, then they truly participate in the decision-making processes (Baldwin et al., 2012). The information must be accessible and transparent to all stakeholders and must include not only a single watershed but also adjacent watersheds and/or transboundary aquifers. This transparency should have mechanisms to verify and generate the necessary confidence and security in the information available in addition to laying the groundwork for conflict resolution by potential agreements.

Certain basic questions must be answered accurately and in real-time:

  • What is the irrigated area?

  • How much water is pumped from an aquifer?

  • How much water is used in irrigation (per plot, farm, water management unit, irrigation area, aquifer, and in a watershed)?

  • What is the amount of water resources available?

  • How do groundwater withdrawals affect associated ecosystems?

  • How do short- and long-term changes in hydrogeological behaviour affect the decision-making processes?

If the quality of water data is assured, then hydrological planning will be reliable, credible, and responsible.

Application of new techniques: Mancha Oriental, Spain

Irrigation surface control

Irrigation surface control (ISC) is one of the main elements in water management. If classic monitoring by field work (mapping, etc.) presents difficulties when water is stored in surficial reservoirs distributed by well-known and mapped channels and irrigation ditches, monitoring is impossible when the irrigation surface is supplied with groundwater or mixed groundwater and suface water. In such cases, a different focus in irrigation monitoring is required because experience in Spain and in other countries demonstrates that the amount of groundwater withdrawals cannot be assessed by classic methods (Castaño et al., 2010).

ISC quantification is probably one of the most interesting applications for remote sensing in water management. Satellite images can provide a digital thematic map with the spatial distribution of different land covers and/or land uses (especially irrigation crops) for any area of the Earth. GIS can integrate these digital thematic maps and distribute them to stakeholders, thus providing participation and transparency in water management. An agreement among the CHJ, JCCM, JCRMO, and UCLM has enabled a remote sensing monitoring model of the Mancha Oriental System Aquifer (Calera et al., 2007), in which the following goals can be highlighted:
  1. To generate an annual database in the form of maps showing the spatial distribution of crops and irrigated areas spread over an area of about 1 million hectares (10,000 km2). The analysed time series starts in 1982. Currently, a multi-temporal sequence of about 12–14 images per year distributed over the growing season is used to obtain the map of irrigated crops. Annual maps are placed on the website of the water authorities.

  2. To share that database with authorities and irrigators, each using this information for their own purposes and competencies. Database sharing has been shown to improve the management and therefore increase productivity. Also, authorities and irrigators can see the information of irrigation crops of any parcel or plot. Nobody doubts the veracity of the data, which is a crucial argument in conflict resolution.

  3. To create a technique of remote sensing aided inspection. The satellite data, obtained in real time, allows us to contrast what is appearing on the surface with the annual operating plan (AOP), previously agreed to by farmers (based on their planned crops), thereby making the field review more effective. Establishing an AOP and ensuring strict compliance is a key tool in water management.

  4. To regulate irrigation rights by using remote sensing data. In 95% of cases, the irrigation-management agreement is adhered to. These rights refer to irrigation prior to 19861 and after that date, saving a situation of lawlessness. Moreover, a recent judgment by the Spanish Supreme Court recognizes that remote sensing cropland maps are admissible as proof in court proceedings as they provide real-time results, reliability, reproducibility, and can be validated by other methods (the judgment can be viewed with these data: STS 3929/2012, Id Cendoj: 28079130052012100381, Tribunal Supremo. Sala de lo Contencioso, Madrid, Sección 5, No. de Recurso: 6539/2008).

  5. To develop and use a tool to display online the temporal evolution of a given property and crop throughout a growing season, and accumulate these data in successive years (Aquastar-ERMOT). An example of this tool, which can only be accessed by authorized entities, is shown in Figure 2.

Fig. 2.

Visual and numerical information provided by the Aquastar-Ermot system. The pointer gives information of any pixel of a plot showing the evolution of the normalized difference vegetation index (NDVI) derived from satellite imagery (e.g. 2011–2014). The NDVI is related empirically with the crop coefficient and therefore with the weekly water requirements resulting from this information. (Basic information to determine the type of crop involved). Source:http://www.teledeteccionysig.es.

Fig. 2.

Visual and numerical information provided by the Aquastar-Ermot system. The pointer gives information of any pixel of a plot showing the evolution of the normalized difference vegetation index (NDVI) derived from satellite imagery (e.g. 2011–2014). The NDVI is related empirically with the crop coefficient and therefore with the weekly water requirements resulting from this information. (Basic information to determine the type of crop involved). Source:http://www.teledeteccionysig.es.

Irrigation water requirements estimation

The traditional system for measuring and controlling water used for irrigation is to place volumetric flowmeters or counters at each water source point. This is a widely used classic measure when distribution is provided from reservoirs through a network of irrigation ditches. However, in groundwater systems it is very hard to monitor tens of thousands of wells, taking into account that the wells are located on private properties accessed only with the owners' permission, quite different to the case of reservoirs and surface water distribution canals.

An example of the difficulty of implementing flowmeters in groundwater exploitation systems was a case in the upper basin of the Guadiana (Spain). To monitor and control groundwater extractions in overexploited aquifers in the Western Mancha and the Campo de Montiel, the water administration invested more than €6.5 million between 1994 and 1996 to install a network of 4,820 well flowmeters (Díaz-Mora, 1999). Once installed, it was necessary to put in place a system to ensure that the flowmeters were maintained and the measurements taken were collected. An economic evaluation of these aspects is complex. Díaz-Mora and managers of the Western Mancha and Campo de Montiel aquifers recognized that it is very difficult, if not impossible, to manage the water administration system by direct measurement flowmeters. In the final report of the Upper Guadiana Plan it is indicated that the total cost of implementing flowmeters amounts to an investment of €100 million, with a maintenance and monitoring cost of €6.5 million per year.

Furthermore, this methodology obviously lacks the capacity to obtain data on the evolution of extractions prior to the implementation of the counters, which makes it difficult to objectively legalize prior irrigation rights (other alternatives and/or complementary methods such as an analysis of electricity consumption are not considered here).

Remote sensing and GIS provide an alternative and/or a complementary approach to the flowmeter method. Satellite images from the 1970s to the present can be used to build picture of water use over time. The procedure is based on the classic method of assigning irrigation water requirements for each crop depending on rainfall, atmospheric demand, and irrigation system throughout its growth cycle (Castaño et al., 2010).

Obviously, if you have the map of crops for a given area, each crop can be assigned its irrigation needs and the requirements estimated at different spatial scales, all by a process of spatial aggregation typical of GIS tools. It can be difficult to acquire a map at this scale, but it is quite common for the classification by satellite images to provide a map with crop groups that have a similar temporal evolution. Each of these classes can be assigned irrigation needs (Martín de Santa Olalla et al., 2003). In this way, we can make an initial estimate of water consumption by plot size, farm, irrigation area, groundwater body, or watershed. To do so, one need only have the maps that delineate each of the spatial scales which will be aggregated (Castaño et al., 2010).

This methodology has been applied routinely by the CHJ and JCRMO in the MOA for monitoring the AOP. Around 1,400 Water Management Units (WMUs) have been established in this area, defined as the set of plots that use water in common, from one or more wells. Some of these are WMUs of a few hectares belonging to a single farmer and others contain hundreds of properties and owners. The crop classification maps are one of the goals of this agreement, and can be interactively viewed by all parties involved.

In AOP, stakeholders (JCRMO) set the volume authorized per hectare, and each one has to appropriately plan the crops and surface area according to the WMUs allocated in order to not exceed the total allocated volume. Monitoring the AOP requires integrating digital maps of irrigated areas with a spatial delineation of WMUs using the GIS spatial analysis tools to estimate the average volume consumed per WMU and compare it with the authorized amount. In the maps of irrigated areas, arable crops are grouped into four classes: spring irrigation, summer irrigation, spring-summer irrigation, and/or permanent. Each is assigned an irrigation water needs category; the maps also incorporate information from other sources such as field work, and so on, assigning other water requirements.

The AOP verification is made possible through a combination of these technologies. System operation is performed in real-time to obtain as much information and transparency as possible, incorporating the latest information obtained by satellite. In the sanctions regime, the JCRMO and CHJ act together, agreeing on a principle of self-regulation, with the JCRMO, through the irrigation jury (see section 2.5 below), punishing violators with fines and the return of the water consumed in excess the following season. Recidivism, or severe cases such as increasing the irrigated area without authorization, involve heavy penalties imposed by the CHJ. Figure 3(a) shows the evolution of records, indicating a high degree of compliance with the AOP, while Figure 3(b) shows non-compliance with agreed irrigation volumes.
Fig. 3.

(a) Comparison of proceedings of the irrigation jury. (b) Groundwater returns jury irrigation. Since 2005, all AOP compliance failures carry with them, in addition to the monetary penalty, a repayment obligation of the water volumes consumed in excess, by not using an equivalent amount plus a 10% surcharge on the next season's irrigation. Source:http://www.jcrmo.org.

Fig. 3.

(a) Comparison of proceedings of the irrigation jury. (b) Groundwater returns jury irrigation. Since 2005, all AOP compliance failures carry with them, in addition to the monetary penalty, a repayment obligation of the water volumes consumed in excess, by not using an equivalent amount plus a 10% surcharge on the next season's irrigation. Source:http://www.jcrmo.org.

Remote sensing allows another, more direct methodology (in transition from research to applicability) to estimate water used. It is based on the ability to obtain the evolution of a given sequence of vegetation cover from satellite imagery, specifically to derive the so-called crop coefficient (Gilabert et al., 2010). Combining this information with the evaporative demand of the atmosphere – the ET reference ET0 (obtained from agrometeorological stations) – serves to estimate the actual ET of irrigated crop (Torres, 2010). An example of this calculation is shown in Figure 4 with the weekly total water needs. The integral along the curve provides the cumulative water needs throughout the growth cycle.
Fig. 4.

Consumption of groundwater flow observed and estimated by remote sensing in an experimental plot of irrigated summer crop such as corn (4.07 × 105 m2 (40.7 ha)) in the year 2014.

Fig. 4.

Consumption of groundwater flow observed and estimated by remote sensing in an experimental plot of irrigated summer crop such as corn (4.07 × 105 m2 (40.7 ha)) in the year 2014.

The consistency and robustness of this method have been studied by many authors such as Bastiaanssen et al. (2000), Martín de Santa Olalla et al. (2003), Tasumi & Allen (2007), and Castaño et al. (2010). The operational limitations of its application is the availability of a suitable sequence of satellite images in the growth cycle, both in frequency and spatial resolution.

In the cases analysed, the combination of remote sensing and GIS techniques allows water data to be shared among the social actors involved and makes inspection and monitoring in the field more effective. The described methodology allows the estimation of water needs to the pixel scale and (using classic GIS tools or GIS tools online) the estimation of the water needs throughout the growth cycle for a given crop. It also allows determination of the spatial aggregation at plot level, WMU, irrigation area, aquifer, and watershed. Based on this method and the experience gained over 10 years, we have been able to establish the budget for this work. So we can estimate a cost type by year campaign of around €150,000 for a typical area of 150 km × 150 km, that is, €6.60/km2.

Groundwater infiltration recharge estimation

Groundwater recharge by infiltration is the process by which water that infiltrates into the ground exceeds ET needs of the root zone and continues to flow downward through the unsaturated zone to the water table where it increases or replenishes the groundwater reservoir or aquifer (Gee & Hillel, 1988). At a given time (typically 1 year), groundwater recharge by infiltration should equal the output volume of groundwater volume plus changes in aquifer storage. This budget is based on the concept that all water inputs (inflow) in a space and time are equal to the sum of all water outputs (outflow) and changes in water storage in the same space and time. In semi-arid climates, groundwater recharge of regional aquifers can vary more than 50% between wet and dry year sequences. Therefore, the suitability of establishing a long-term annual recharge value to assess the quantitative status of a hydrogeological system is questioned. Indeed, interannual climate variability may affect the representativeness of the estimated available resources, especially in semi-arid areas, where annual rainfall can drop dramatically for several consecutive years. For example, rainfall in the city of Albacete for the hydrological year of 2004/2005 was 120 mm, while for the year 2009/2010 it was 450 mm. A single fixed value for the available resource can therefore be quite misleading in semi-arid areas (Directive, 2006). Consequently, it is necessary to know in near real-time the value of the resources available. An example is the management adopted by the California Department of Water Resources, where there are two values for the available resource, one for normal years and one for years within a drought sequence (CDWR, 1994).

In the Mancha Oriental System, more than 50% of the available water resources come from rainfall infiltration. The processes of direct recharge by rainfall infiltration are well known, but not its spatio-temporal quantification based on precipitation, temperature, soil characteristics, vegetation, and slope. Our experience has led us to develop a water budget model in the soil in which all these variables are distributed in space and time. The result was the Hidromore model, which estimates ET and recharge by rainfall infiltration over large areas using remote sensing and GIS. It runs on a daily basis and determines the ETc (crop evapotranspiration) through the implementation of the FAO-56 dual methodology coefficient under standard conditions and water stress (Torres, 2010).

Hidromore considers soil to be a storage medium that allows homogeneous water inputs by rainfall and irrigation and outputs by ET, runoff, and percolation. The daily water budget in the soil layer is calculated as a raster based on daily precipitation, ET, runoff maps, and infiltration, which together provide the potential of aquifer recharge on which the simulation is based. In irrigated plots where optimal moisture and nutrients remain in the soil to ensure proper phenological development of the crop, it is assumed that it is equal to ETc irrigation needs. However, in non-irrigated areas, where these optimal conditions of soil moisture are not achieved (as occurs in semi-arid climates), the ETc only provides an estimate of the maximum value of the actual ET of the vegetation cover.

Mathematical modelling of the hydrogeological system

Groundwater mathematical modelling is any method of calculation that represents an approximation of a groundwater system (Anderson & Woessner, 1992). Although mathematical modelling of groundwater is, by definition, a simplification of a more complex reality, it has proven useful to provide information on the complex behaviour of hydrogeological systems to address a number of groundwater problems and to support decision-making (Barnett et al., 2012). In addition, groundwater models are ideal for integrating all hydrogeological databases for the simulation of hydrogeological behaviour against different management scenarios and plans to modify the same inputs and outputs. The spatial and temporal assessment, quantification, and prediction of hydrogeological systems are necessarily performed using numerical models due to their ability to represent the complexity of hydrogeological systems (Sophocleous, 2002; Pisinaras et al., 2007).

Regional aquifer modelling has proven to be the best tool for water planning and for the management of large areas. The availability of powerful processors and GIS tools has spurred exponential growth in regional groundwater modelling. Large-scale groundwater models have been built to analyse regional flow systems, simulate water budget components, and optimize groundwater development scenarios. There are examples ranging from groundwater systems consisting of hundreds of thousands of square kilometres (e.g. Death Valley and the Great Artesian Basin in the USA; Zhou & Li (2011)) to systems of dozens or thousands of square kilometres such as the High Plain Aquifer (USA) (Gaisheng et al., 2012) and the Beijing Plain (China) (Wang et al., 2009).

The MOA is one of the most extensive carbonate aquifers in Spain, extending over 7,000 km2. (Figure 1). In the interests of conducting a groundwater flow model of the aquifers in the MOA and their relations with the Júcar River, this model was prepared through an agreement among the CHJ and JCRMO, the Polytechnic University of Valencia (UPV), and the University of Castilla–La Mancha (UCLM) (these two universities belong to the Júcar River Basin area). The middle-term objective of this model was to produce a useful tool for the sustainable management of water resources in the MOA that can also be used for decision-making by both the water management authorities and stakeholders interested in its direct use.

This model is updated annually based on our hydrogeological knowledge of the system (Sanz et al., 2009, 2011): (a) the geometry of the hydrogeologic system, (b) parameterization of the aquifer units, (c) the establishment of initial conditions, (d) determining boundary conditions such as side inputs, rivers, and recharge by rainfall (results obtained by the Hidromore recharge model), and (e) quantification of external actions (determination of groundwater withdrawals for irrigation by multi-temporal analysis and multispectral satellite imagery following the methodology of Castaño et al. (2010) (points 2.1 and 2.2 of this paper)). The following features can be highlighted:

  1. Performing mass balances for assessing system behaviour. Representation of the real situation, both in the flow through the different river sections and the groundwater heads as recorded in the field.

  2. The results allow us to obtain detailed behaviour for the MOA and its spatio-temporal relations with the Júcar River.

  3. Estimating and performing pumping scenarios used to predict long-term system behaviour.

  4. Simulation of urgent measures such as replacing pumps and/or public offerings to acquire water rights in the face of severe drought conditions.

Participation and transparency in MAO

One of the fundamental principles of good groundwater management is transparency and participation of all stakeholders in the decision-making process. The availability of clear and credible information is absolutely necessary for a transparent governance environment. In Spain the management and control of groundwater abstractions has been a difficult task at government level since the introduction, in 1985, of a new Water Act. Management was further complicated by the lack of administrative resources of the water authorities, especially at a critical period (1985–1988) when groundwater exploitation was more widely developed due to the implementation of agricultural expansion policies. The lack of control and organization of the intensive use of water led to overexploitation of aquifers. In Spain, overexploitation is defined on the basis of the negative balance between abstractions and recharge that affects holdings and associated ecosystems (Article 171.2 of the Public Water Regulations). The water authorities have the legitimacy to declare an aquifer as overexploited (López-Gunn & Rica, 2013).

In Spain, the MOA is an example of land use transformation due to the expansion of irrigated crops. The MOA was the main resource of groundwater to supply irrigation surfaces during the 1990s, where there was an almost total lack of control and management of wells constructed for irrigation purposes. This process led to the appearance of a number of problems: (a) general decline in groundwater levels linked to, (b) social and environmental pressures, (c) pressure from other adjacent operating systems that share resources and, (d) the lawless state of certain wells. In addition, the severe drought in the mid-1990s triggered the creation of a stakeholders association called JCRMO to address these problems which had not been previously raised due to the fact that farmers faced the task of land management as individual irrigators. The JCRMO was created as a public corporation based on the provisions of the Spanish water law and participated with the water authority developing the AOPs and sanctioning, via an irrigation jury, any breach of agreements (Gutierrez Visier, 2013). An irrigation jury consists of a group of farmers, water authorities and water managers that oversees and can sanction the breach of an agreement (irrigation surfaces and water applied).

However, as pointed out by Baldwin et al. (2012), for any decision-making process it is essential to have robust information (ISC, irrigation water requirements, groundwater recharge, and relationships between surface and groundwater), which is credible/trustworthy for stakeholders, managers and society in general, and defensible by scientists and independent reviewers. But the JCRMO has not the human and technical resources necessary to handle the necessary work to obtain such information. For this reason, the JCRMO promotes collaboration agreements with both water authorities and the regional university in order to obtain the necessary information. The agreements assure the involvement and participation of the parties and that the results are accepted and validated.

Thus, the information obtained in the agreements (see sections 2.1–2.4) is shared among stakeholders, water managers, and scientists with constant feedback. Several technical sessions organized by the JCRMO are held throughout the year, in which farmers are promptly informed about the progress of the studies. Among other questions, in accordance with the AOP, the area a farmer claims to have irrigated is verified by remote sensing techniques. The AOP is agreed every year in a general meeting in accordance with the state of the aquifer. Time series of satellite images are used regularly in the proceedings of the irrigation jury in order to verify the irrigation surfaces and water applied, increasing the efficiency of field inspection and withdrawals control. The evolution of crops and maps that identify the areas and crops irrigated are derived from a time series of images. This information is accessible via the internet by farmers, water authorities, and technicians/scientists through webGIS tools (see ERMOT, 2015). These tools and the groundwater modelling generate trust in the parties and allow a participatory and transparent management, though obviously not without tensions and conflicts. The university offers training courses and workshops for technicians and farmers to handle the new technologies developed by the university.

Summary and conclusions

Water management in agriculture faces many challenges in different areas, sectors, and scales, which are amplified in the case of intensive groundwater use, in which the principles of classic regulation of surface reservoirs and ditches are not applicable. One of the essential features of an efficient and sustainable system of collective management of common resource is an adequate monitoring and control structure of withdrawals, recharge, and aquifer system evolution. Such a monitoring and control system requires instruments capable of establishing the powerful management, regulation, and control of water use. All parties need to agree that these management tools must be prioritized over traditional policies of greater resource supply (either from desalination and/or from transfers) as well as over restrictive policies that might be adopted (e.g. limiting supply). Repeated experience shows that without knowledge, participation, and transparency in management and control, demand expands uncontrollably, and policy restrictions unleash ‘hydrological lawlessness’.

In addition, a system of differentiated and graduated sanctions is also needed, with sanctions that are understood by users and seen as fair in the hydrogeological simulation of the effects produced. To that end, a new feature of emerging water management is the need to rely on the basic principles of participation and transparency to reflect the multiple regional, technical, economic, environmental, social, and political aspects that allows the cooperation of the different social actors involved.

Participation requires that both administrations and stakeholders share adequate and updated basic information on irrigated areas, water origin and evolution of the aquifer system, and its relationship with surface ecosystems. Users also have to participate in decision making, establishing access to that information transparently for other stakeholders. Transparency must be applicable within a given territory, but should also include other areas within a watershed and a few other basins. This transparency should have mechanisms that are verifiable and generate trust and confidence, plus lay the basis for conflict resolution by agreement. Earth observation technologies have reached a point of maturity and development in the generation of products that allows their integration with GIS and ICT to establish tools to help solve these challenges for the integrated management of water resources.

The experience described in this paper shows the operational application of these tools to irrigation advisory services by means of the detection of irrigated areas and the estimation of water consumption, and hydrogeological simulation behaviour in space and time. The tools are essential for efficient water management. They are also shown to be powerful tools that facilitate participation and transparency by allowing interactive information sharing, facilitating decision-making, and aiding conflict prevention and resolution. As shown, internet-based platforms (based on GIS technology) provide access to spatial information on irrigated land and water consumption at different spatial and temporal scales, under agreed-to criteria and restrictions.

The installation cost of these new technologies is very small, almost negligible when compared with the costs of agricultural production, including the costs of water and energy as well as the costs of irrigation modernization or simply maintenance costs, without even considering the investment needs of classic control systems such as flow meters.

So far, the argument for delay in the implementation of these new technologies has been their experimental nature. The operational nature of the experiments described shows the maturity and development achieved, whereby the application is ready and requires a decision to be accompanied by a process of learning and familiarity with the products and communication channels for different social actors, technicians, and managers. In this regard, the overall progress that our information-based society is achieving in all areas is driven in the direction of incorporating these technologies for the participatory and transparent management of water resources.

Acknowledgements

Special thanks go to the Júcar Water Authority (CHJ) and stakeholders (JCRMO) in the Mancha Oriental System for providing the necessary information. The contents of this paper do not represent the views of the CHJ and JCRMO.

1

Until 1985, groundwater rights in Spain were governed by the Water Act of 1879, which stated that groundwater resources were privately owned. In 1985, a new Water Act was introduced and stated that groundwater is public property. While this seems to be a distinct change in groundwater rights, not much has changed, as it only really applies to a minority of wells (those drilled since 1986). The rest could choose to keep groundwater on private property or waive their rights to the state, receiving administrative state protection and the ability to continue using their wells under similar conditions for a period of 50 years. It is estimated that in the whole of Spain only 10–20% of the wells drilled prior to 1985 were enrolled in either, and that many new wells and boreholes have been constructed since 1986, without presenting any application for administrative approval.

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