Keywords

5.1 Introduction

During the past two decades, water resources in Mexico have been under pressure due to extreme meteorological events like droughts , particularly in the northern part of Mexico . This situation has created several kind of problems among the users in the basins, particularly between the urban and agricultural water uses . Many national and international institutions and researchers have tried to develop strategies and methodologies to generate various scenarios to face this water-scarcity problem, but one of the main obstacles is related to the lack of reliable information from the irrigation districts or institutions who are in charge of measuring or generating the information needed to achieve a good analysis and to identify the kinds of alternatives. In hydrological study and analysis of watersheds, it is imperative to have data of various types, such as climatic data, land use, soil type and consumptive uses in quantity and quality, in order to carry out simulations that generate results for proposing adaptative measures to face extreme events, such as droughts and floods, as well as compliance with water demands for various purposes, generating public policies that guarantee the availability of water in the required quantity and quality. This production of basic information should be incorporated within a standard structure that enables its management in an efficient manner.

For many years, in the Mexican hydrological basins, a particular situation of having access to information related to water uses has been identified, in particular the updated water balance that enables knowing water availability for improving the content of the Mexican databases. Based on these updated data models , researchers could have access to all information needed to create water management models to generate scenarios for a better water allocation . Due to an increase in irrigation areas and population in big cities, the pressure on water resources is increasing to satisfy the water demand of the all users in the Mexican basins.

Binational watersheds, such as the binational basins of the Colorado River and the Rio Grande that are shared by Mexico and the US, represent a very special challenge due to their complexity. It is extremely important to establish protocols and joint mechanisms for the generation of hydrological, meteorological, and hydraulic information, among others, that allow the generation of data models in a joint manner that considers a standard structure to facilitate the exchange of information as established in various documents and international conventions for basins shared by more than two countries, such as the Helsinki Rules (ILA 1966) and the United Nations Economic Commission for Europe during the Convention in 1995 (UNECE 1995). Having the same data model for all the countries that share a hydrological basin will allow carrying out comparative analyses of various results produced by their respective simulation and management models, with the goal to propose measures that improve the distribution of water resources in these hydrological basins. These types of datasets are fundamental to generate water-management models for improving water allocation in the transboundary basins of Mexico , both in the north and in the south of the country.

As in many watersheds around the world, the information related to the physiographic characteristics in the Mexican hydrological basins are produced using traditional techniques and old or discontinued maps, field surveys and delineations of the watershed division created by hand using photogrammetry. Fortunately, computational techniques supported within geographic information systems have been developed in the past decades, which help hydrologists to make the parameterization of watersheds in a faster, systematic, and efficient way, reducing time in hydrological analysis and avoiding errors (Spence et al. 1995).

From the development of information in raster format, such as digital elevation models, it is possible to generate hydrographic networks or physiographic parameters of watersheds in places where the river system is not available, or where the quality of the hydrographic network is deficient (Jenson and Domingue 1988 ). The matrix arrangement in the structure of the raster format offers a great advantage for hydrological analysis and generates hydrological information that can be used in simulation models in basins of various sizes (Lacroix et al. 2002). In some hydrological regions of Mexico , hydrological parameters are being generated from digital elevation models, such as the calculation of the drainage area, transit time, and hydrographic network, among others, as established by Tribe in 1992.

Another significant change in the generation of hydrological parameters is the appearance of automated processes using remote sensing, which enables obtaining precipitation data automatically and transmitting them to a distributed hydrological simulation model, to estimate the corresponding runoff and thereby know the amount of water available.

Taking into account the need to have a standard structure for the management of water data, the Center for Research in Water Resources (CRWR) of the University of Texas at Austin developed a particular data model structure called ArcHydro . This will be used as a basic structure for managing all data related to water management , incorporating the spatial and temporal information contained in a relational geodatabase. This data model has the ability to assign attributes and establish relationships and connections through the creation of geometric networks between hydrological information , incorporating all elements in a geographic information system (Maidment 2002).

For this reason, it is imperative to attend to the problem related to the availability of water data, both quantity and quality, to be used by the researchers to generate public policies for improving water management in the Mexican hydrological basins. All the water data need to be incorporated into a standard structure to enable easy access to the simulation models for various kinds of analysis across many sciences , such as the hydrological, environmental, economic, and social, and then to generate recommendations for the decision makers considering various scenarios.

5.2 Current Conditions of the Hydrological Basins in Mexico

For many years, the Mexican federal government has invested a lot of money to improve the hydraulic infrastructure in the hydrological watersheds, seeking to improve water management , without the desired results. This situation is the result of sporadic and isolated actions because the decision makers did not take into account other factors such as the opinion of society and local conditions and did not include the experience of researchers who have developed water management plans taking into account all these variables. These water management models have included data models and their relationship with the simulation models to produce results that could be used to establish public policies regarding Mexican water law. An increase in the population is expected in most of the Mexican hydrological regions , which will result in problems in the supply of drinking water and handling of sewerage. Currently, there are already serious problems in this type of infrastructure, so the three levels of government in Mexico must work together to find integral solutions that make it possible to deliver the required service. For this, the integral management of water resources in the Mexican basins is considered, which also enables satisfying the demand for the diverse uses of water, not only the water supply for urban areas. The development and implementation of data models that enable the provision of reliable information in the appropriate formats will be fundamental for the development of these water-resource management models. Due to the climatic variability in the Mexican hydrological basins, it is fundamental to analyze in detail the behavior of precipitation , for example, because in the northern part of the country it could be around 160 mm per year and in the southern more than 4000 mm per year, for example, in zones of Chiapas state. Another important topic to be considered is the migration of people from rural to urban areas, demanding more water for urban use in the megalopolis such as Monterrey, Guadalajara, Mexico City , and Puebla. Also, the main part of the gross domestic product is generated in zones of Mexico where there is not enough water to satisfy the demand for consumptive uses, generating big risks for the local economies. For these reasons, it is imperative to take into account many factors to establish public policies, such as who is creating more pressure in hydrological basins by demanding more and more water, which sectors are participating in the water distribution and how they could improve their processes to save or reuse water to satisfy the demands. Also, it is important to review the hydrological basins that have restrictive water-use rules and reconsider these restrictions using the information contained in the relational models and the results of the simulation models. Another important scenario to be reviewed is the participation of private companies in water distribution in the urban areas because this participation could make water management more efficient in these zones, improving the water quantity and quality for the population. There are some good examples in Mexico , such as the water company of Leon, Guanajuato or Monterrey, Nuevo Leon.

Unfortunately, in many of the Mexican basins, the spatial and temporal information related to hydrology are disconnected. For example, there are serious errors defining the physical boundaries, and in other cases, the time series related with flow rates, climatic information or water quality are not complete within their registration periods, leaving many gaps in the structure.

For the reason just mentioned, hydrological, meteorological, hydraulic, and all information related to water administration need to be public and supported on standard platforms by the Federal Government of Mexico , throughout the National Water Commission (CONAGUA) and the state agencies of Mexico . This information should include states covering the watersheds, the hydrographic network, lakes, dams, hydrometric and meteorological stations, and the polygon describing the watershed’s boundary of the Mexican hydrological basins, provided by the CONAGUA, research institutes as the Mexican Institute of Water Technology (IMTA), universities, international agencies such as the Mexican International Commission of Water and Boundaries (CILA), and the National Institute of Geography and Information (INEGI), among others.

As a first approach, Table 5.1 shows the main information that should be included to standardize the water information in Mexico .

Table 5.1 Summary of the main information in the Mexican hydrological regions
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According to the author’s experience, errors exist in some geographic information related to the hydrography data in the Mexican watersheds, which includes inaccurate positions of the gauging stations; bad editing processes to generate the hydrographic network producing disconections in the river system; and errors during the projection process that generate a wrong position of many of the geographic information, such as lakes and dams . Figure 5.1 shows some of the described errors so that users can see the wrong direction of some rivers in the Rio Conchos watershed.

Fig. 5.1
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Common errors in the Mexican hydrography

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The Mexican agencies use the Geographic Coordinate System and Lambert geographic projection to create their geographic information. This is the INEGI, the agency in charge of producing this information in collaboration with other institutions.

5.3 Methodology

5.3.1 Developing the Scheme of the Hydrological Data Models

As the first step to create a data model , known as a geodatabase in GIS jargon, it is necessary to create a framework, perhaps using the Visio software, to serve as a standard framework that incorporates specialized structure such as a UML file . This framework follows a specific and predefined data-model philosophy, incorporating changes in the structure of the attribute tables to add as many fields as required by the simulation models, or to satisfy the specific information required by the decision makers, primarily in the Mexican federal government.

To generate a personal geodatabase for the Mexican watersheds following the predefined structure of the UML file, an Access version of the UML can be applied to an empty geodatabase to recreate the feature datasets, feature classes, tables, and all the relationships among them (Fig. 5.2).

Fig. 5.2
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Standard data model structure proposed for the Mexican basins

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5.3.2 Mexican Hydrological Basins: How to Improve Their Temporal and Geographic Information Format

It is fundamental and very important to create hydrological and water management models in the Mexican watersheds that would provide the required information to avoid flooding problems, to mitigate the negative effects of droughts or to improve the water quality in the hydrological basins (Patino-Gomez 2005). However, the data models must incorporate all the elements related to the water resource , such as sources of availability, climatological variables, orographic characteristics of the hydrological basins, type and use of land, and economic activities, among others. All this interrelated information must establish the necessary arrangements and structures to generate a first simple model of water management .

In Mexico , various efforts have been made to create or improve, in a more efficient way, databases related to water resources , but these datasets incorporate water quantity and quality information separately. Another problem is the quality of the available information because, while there is sufficient information for some Mexican hydrological basins, sometimes the quality of this information is not correct, presenting gaps in the historical series and geographic positions, or including nonsense data that affect the result of simulation models. Unfortunately, the hydrological regions of Mexico do not have a standard structure that could store water quality and quantity information to establish a relationship among the various elements and thus would enable identifying actions to improve or make more efficient the water allocation in the entire hydrological watershed. Also, it is necessary to incorporate climate-change information in these databases since it is a phenomenon that will significantly affect the water availability and the water quality in the Mexican basins, putting at risk meeting the demands allocated for various uses.

A communication structure and protocols should also be proposed for sending and receiving information between the data models and the simulation models in the hydrological basins. This sequence in the simulation will enable an integrated simulation system to make decisions in the presence of an extreme event, such as a hurricane , for example.

The ArcHydro data model seems to be one option because this is a standard structure that allows very easy access to water information required by simulation models in a very efficient way. Indeed, the most recent version developed at the Universidad de las Americas Puebla can establish the required communication with climate change scenarios to analyze precipitation and temperature anomalies. This special structure is based on the geodatabase concept contained in the GIS platform, which incorporates hydrological, geomorphological, hydraulic, and all the spatial and temporal information related to the water resources of the Mexican hydrological watersheds, as shown in Fig. 5.3.

Fig. 5.3
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Integration of water related data for the Mexican basins

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As the first part of the process to harmonize the water data in the Mexican hydrological watersheds, it is fundamental to create the standard structure of a data model or the ArcHydro data model for each of the 13 administrative hydrological regions following the division used by CONAGUA, using Geographic Information System technology that includes spatial and temporal information from various sources. These geodatabases should preserve the names used by CONAGUA to maintain the institutional identifiers.

Each of these geodatabases just mentioned would be a particular data structure to include georeferenced geographic information, as well as historical information from the hydrometric and meteorological stations located in the watersheds. One advantage of the use of relational databases is related to the creation of geometric networks. This network establishes the connection between the rivers and the gauging stations, for example, and enables finding any errors or disconections in the hydrographic network. The connectivity in the network makes possible tracing the contaminants in the rivers and provides the required information to calculate the concentration of contaminants in the water. Summarizing, the Mexican data models would contain all the information related to water resources in a systematic and standard structure, which makes it possible to modify the framework for specific conditions, depending on the zone of the country where the watershed is located.

5.3.3 Data Collection

As was mentioned, information created by different agencies or institutions in Mexico does not follow the same criteria or structures, so it is usually produced and published in different formats. This is a big problem for the users because, before they can incorporate this water data into simulation models, a preprocessing step to correct errors or to prepare the information in an efficient way is required. It is important to mention that all the official water information in Mexico is produced and disseminated usually by the INEGI and CONAGUA. In some cases, users could find information from other water projects developed by companies, universities, or research institutions, but it is neccesary to review and analyze it to check if it is appropriate and does not contain the original errors. Part of the original geographic information for one of the Mexican hydrological regions is shown in Fig. 5.4.

Fig. 5.4
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Original water data in the Mexican hydrological regions

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Temporal information in the hydrological basins of Mexico comes from various institutions, who report it in different structures and in many cases with several gaps in it. It would be more useful to have all the historical data related to gauging stations in one place, following a predefined structure that makes possible its topological connection with the spatial georeferenced information. This is another important advantage of using relational database to have all water-related data interacting among their elements in a dynamic way and within a standard structure. Figure 5.5 shows a specific structure for handling the historical information related to the gauging stations located in the Mexican hydrological basins. It would enable knowing from where that information is coming and what kind of variable has been incorporated into the relational database.

Fig. 5.5
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Proposed structure for the historical data in the Mexican basins

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The FeatureID field describes the public identifier assigned for the official agency, and the TSTypeID includes the kind of variable. Another important field is the GroupID that describes who is publishing the information. The TSDateTime and the TSValue field correspond to the collection date and its corresponding value.

5.3.4 Raster-Network Regionalization for the Mexican Basins

In some projects in small watersheds around the world, the use of a Digital Elevation Model (DEM) with high resolution to determine hydrological parameters is very common. Recently, the studies on bigger watersheds have generated a particular interest in new models and methodologies (Kite 1995). In particular, some Mexican hydrological basins are too big to be processed as one huge raster, which could be a DEM or a climate-change raster. The raster-network regionalization technique proposed by Patino-Gomez (2005) could be used to analyze these kinds of huge basins. This procedure consists basically in dividing a very big hydrological watershed into smaller watersheds to avoid technical or computing problems during the geoprocessing of a DEM. The raster information about the Mexican hydrological basins is not common, and INEGI has published the whole DEM for the country, but there is no methodology reported to generate one DEM or another kind of raster for a specific hydrological region. In this direction, the authors have been proposing to implement this kind of methodology in various projects to facilitate access to this information. Figure 5.6 shows the DEM for the whole country and the result for a specific Mexican hydrological region , including also a climate-change scenario that could be very useful for vulnerability analysis in the climate-change context.

Fig. 5.6
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DEM the Papalopan basin in Mexico

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5.3.5 Development of the Mexican Geospatial Database

As was mentioned and as is common in many watersheds around the world, knowledge and hydrological information available in some Mexican basins is not enough or contains some errors and is of poor quality. For this reason, it is important to have a data model to compile, analyze, and make corrections, the geospatial database format being an excellent option. This kind of structure can handle the information in an efficient way and put all the water data in the appropriate structure required by the simulation models. Creation of Mexican geodatabases for the whole country is imperative. These geodatabases would manage all the water data in the corresponding watershed, incorporating the hydrographic networks, states covering the watersheds, lakes, dams, and the historical information from the gauging stations. Also, this kind of structure will make possible establishing relationships among georeferenced information and the time-series data (Fig. 5.7). Another important advantage of using this relational structure is the feasibility to link the geographic information with the time series of hydrometric or water-quality stations, so it would be possible to establish a topological relationship in the same data model for the 13 Mexican hydrological regions .

Fig. 5.7
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Integration of water related data for the Mexican basins

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All the geographic information from the Mexican basins usually is created as a shapefile format, but this format does not allow establishing the rules and topology among the various elements that describe the hydrology in the basins, so these shapefiles would be incorporated into a feature dataset assigning and standardizing automatically the official projection parameters. Also, the personal geodatabase could have as many feature datasets as required by users or decision makers, and all information would be in just one access file.

The principal features of the proposed relational geodatabases are mentioned below:

  • Monitoring points: Monitoring points are gauging stations, such as hydrometric and climatological stations, located in the appropriate position where it is important to measure the water or climatic variables.

  • Waterbodies: These features include all dams, lakes, and lagoons, among others. Also, very wide rivers could be considered as a waterbody for the hydrological analysis of the watersheds.

  • Watersheds: This component corresponds to the drainage area flowing into the river system as part of the surface streamflow. If it is necessary to divide Mexican watersheds for specific purposes, these new drainage areas could be generated from the DEM.

To have the most robust data model for the Mexican basins, the authors propose establishing several relationships among the components just described and to link the time-series data to these elements (Fig. 5.8).

Fig. 5.8
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Relational data model components

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To complete the data models for the Mexican hydrological regions , it is necessary to incorporate all the shapefiles related to the water data into the feature datasets, which are one of the most important components of the relational database. These feature datasets should have projection parameters and extent properties. One of the main recommendations is to add the largest geographic feature class into the feature dataset first, when a geodatabase is created; otherwise, some errors could be reported when new larger georeferenced information is added to this feature dataset.

Usually, the Mexican water data has a public identifier, but it is imperative to have an internal identifier within the data model for all the geographic features. These internal identifiers would be used to establish the relationships and interconnections among all the geographic feature classes contained in the geodatabase and enable communication with the simulation models in order to generate useful information, such as floodplains or alert systems, for decision makers.

Another important advantage of using relational database for the hydrological regions in Mexico is the creation of a schematic network that would enable connectivity among the hydrography and the gauging stations, as is shown is Figs. 5.9, 5.10, and 5.11, and from which hydrologic or water management models can read the water-related data.

Fig. 5.9
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Schematic network proposed for a Mexican sub-basin

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Fig. 5.10
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Political division of the rio Bravo/Grande basin

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Fig. 5.11
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Primary tributaries of the rio Bravo basin

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5.4 A Case Study: The Rio Bravo/Grande Basin

The río Grande/Bravo basin, one of the most important binational basins, covers parts of five states in Mexico (Chihuahua, Coahuila, Durango, Tamaulipas, and Nuevo Leon) and three states in the US (Colorado, New Mexico , and Texas).

In general, the hydrological basins located in northern Mexico are characterized by having precipitation below the national average. This is a determining factor given that the main irrigation districts are located in these regions. In addition, the droughts that occur are more intense and recurrent, affecting the local economy of this basin because it affects the agricultural and livestock sector significantly. The other problem is the migration to urban areas, which generate a greater water demand to satisfy the needs of the population. Given the exposed conditions and association with the phenomenon of climate change, decision makers need to rely on integral studies that incorporate all the variables through the use of technology and automated systems, to improve water management in Mexico , and thus to guarantee the conservation of the ecosystems and sustainability in the watersheds.

The federal government of Mexico is aware of the importance of having water-management plans to allocate water resources in an efficient way under various scenarios of water scarcity or under a specific hydrometeorological event. This is so, in particular, due to the importance of the economic, social, political, and environmental aspects, in the transboundary basins. As part of the process to improve water management in the hydrological basins in Mexico , it is fundamental to generate or to improve the data models containing all the water resources data and climate-change scenarios in a standard structure, from which users can get the data for the simulation models in an appropriate format. This work is one of the main goals of a project financed by the Mexican National Science and Technology Council (CONACYT) that considers the development of a huge relational data model that could be the example for the rest of the Mexican hydrological regions .

During this project, it was possible to explore the possibility to incorporate hydrological information not just from the Mexican agencies, but also from the US agencies who use different formats and structures for handling this kind of information. All information coming from both countries were incorporated into a relational data model using the ArcHydro structure. This geodatabase could assist reinforcing the negotiation process between Mexico and the US for the water allocation in this important binational watershed, providing the information required by the decision makers.

As occurs in most of the Mexican hydrological regions , the original information from the Rio Bravo basin was found to be in various different scales and structures. One of the most common structures to manage the geographic information by the CONAGUA is the shapefile. However, this particular structure has many limitations, so it was converted as a feature class and incorporated into a relational database created for the whole basin. Regarding historical data, the collection of temporal information began identifying the climatic, hydrometric, and water-quality stations located in this basin. The information was collected from governmental agencies and other research projects in progress that are available for the case study area. Following the ArcHydro structure, it was possible to have and relate georeferenced and time-series data in just one structure. The result is shown in Fig. 5.12.

Fig. 5.12
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Final relational data model for the rio Bravo hydrological region

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Another advantage of using this relational data model is that regionalized climate-change scenarios can be projected and incorporated within the same geodatabase, thus providing the opportunity for decision makers to analyze, in space and time, anomalies of temperature and precipitation supported by a GIS platform (Fig. 5.13).

Fig. 5.13
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Temperature anomaly projected to 2030 in the rio Bravo basin

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Finally, the connection of this kind of data model with simulation platforms is feasible and very useful. The authors propose an integration of hydrological processes as part of the water management plans in the Rio Bravo basin, distinguished by its approach to managing supply and demand, working on the water-balance principle. Based on the relational data contained in the geodatabase, it is possible to develop scenarios to improve water management under various hydrological conditions, taking advantage of the use of the hydrographic network created in this basin as is shown in Fig. 5.14. This network was created among 1.5 million reaches in the countries.

Fig. 5.14
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Hydrographic network in a binational hydrological region

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5.5 Conclusions and Recommendations

The Mexican hydrological basins suffer from a deficit of hydrological information and an adequate structure to carry out the studies of water availability necessary to determine the volumes of water for the various uses, as well as to face extreme events such as drought . It is essential to have the appropriate information and modeling systems to generate scenarios that make possible generating alternatives concerning the distribution of water. These proposed alternatives are fundamental mainly in the zones where water resources are over-allocated.

Climate change or extreme hydrometeorological events in Mexico , such as droughts , have caused conflicts among the various users due to the demand for water. Aware of this situation, the Mexican government has recognized the importance and urgency of the development and use of new technologies and simulation models to enable establishing public policies for improving water management in the Mexican watersheds. Unfortunately, water-related data from the Mexican hydrological regions have been produced and published in different structures, including errors and poor quality, so this original information needs to be analyzed to identify the errors and then fixed.

The development of structured data models containing georeferenced and historical data, such as hydrological, meteorological, and water-related data for the hydrologic administrative regions of Mexico is proposed by the authors to manage the water data in a more efficient manner in Mexico . These integral relational geodatabases, one for each Mexican hydrological region , should compile, integrate, and relate all the geographic information and its corresponding time-series data. They would enable finding in one place all the water resources data, which will provide the required information in the appropriate structure for the simulation models, generating various scenarios. This is particularly relevant for negotiating among the various levels of governments in Mexico for sharing water resources within the country. Another important advantage of using this kind of relational database is the application of an appropriate and useful methodology for the automatic hydrological analysis of very large to huge Mexican watersheds, making possible the use of computational tools to create systematic processes as part of the hydrological modeling in the watersheds.