INTEGRATION OF WATER INFORMATION AT A REGIONAL SCALE.

Transcription

1 INTEGRATION OF WATER INFORMATION AT A REGIONAL SCALE. Xabier Velasco Echeverría, Pablo Echamendi Lorente, Jesús Francés Iribarren. Trabajos Catastrales, S.A. Ctra del Sadar s/n - El Sario Building Pamplona (Spain) Tel: (+34) Fax: (+34) ABSTRACT To help on water management and decision-making, a hydrographic geodatabase of the Navarre water related features (SIAN) has been developed within a GIS. The features contained in the geodatabase are modeled as a geometric network that maintains connectivity between them. On the other hand, the water supply network of the region (SIAB) is also modeled as a geometric network, not to help on network management but to estimate further developments of the distribution network. Although both projects started with different purposes and criteria, the necessity to establish a relationship between the networks is pointed out in order to assure the quality and quantity of the water supply for civil, industrial and agricultural activities without over-exploiting the natural resources. Key Words: ArcHydro, Water Frame Directive, natural network, water supply networks. 1. INTRODUCTION During the last years a great enhancement in GI techniques applied to environmental sciences, and more specifically to hydrology and hydraulics has been carried out. For this reason, environmental authority at the region of Navarre (Dirección General de Medio Ambiente) is concerned about the application of the latest Information Technologies for environmental information management and is developing its own Geographical Information System (SIAN). At the moment, SIAN wishes not only to chart all the water related data but also to make a system capable of helping with water management and decision-making. This interest links with the necessity to implement the Water Frame Directive (WFD), which is now one of the main issues for the water authorities all across the European Union. At the same time, the water supply agency of the Navarre region (Dirección General de Administración Local) is also developing its water supply management system (SIAB), not to help on network management but to estimate further developments of the distribution network, also to assure the quality and quantity of the water supply for civil, industrial and agricultural activities without over-exploiting the natural resources. Yet SIAN and SIAB have different purposes, both systems wish to be integrated within the regional information system (SITNA), which stores tourist, cartographic, administrative, cadastral, street, health, urban planning, infrastructures, agricultural and environmental information. In practical terms, integration is not only a wish but also a necessity for the regional development.

2 2. PROJECT AREA The Navarre region occupies 10,421 km 2 and is located in the North of Spain. It shares a border of 163 Km with France in the upper area. A population of 578,210 lives in the region, half of them in the capital city, Pamplona. Three main basins exist in Navarre: one flowing to the Mediterranean Sea (Ebro), which occupies the 90% of the surface, and the others flowing to the Atlantic Ocean (Norte) through Spain and France. In total, Navarre has kilometers of rivers, distributed across the three main climatic areas: Alpine, Atlantic and Mediterranean (Navarre government, 2004). Finally, to get an overview about the complexity of the water management in the region, it is worthwhile to mention that in Navarre, three main agencies exist independently from each other: Ebro Hydrographic Confederation (CHE), North Hydrographic Confederation (CHN), and the Government of Navarre. 3. STATE-OF-THE-ART All the data the water supply agency owned, was in CAD format and outside of any reference system. Because the data came from seven different companies and agencies, there was not a common structure for the information. In some cases, there was not even a relationship between the geometry and attributes. The position of the environmental authority data was not much better, because all the information it had was in SPANS format, at different scales and with diverse quality depending on the layer theme. Concerning topology, the SIAB layers were geometrically connected and correctly digitized according to the flow direction because, prior to this project, there was an application (GADA system) using that information. On the other hand, the SIAN layers presented no connectivity and the digitizing procedure did not take into account the flow direction. Finally, no metadata for the SIAN layers was available. This made it necessary to research the information contained in the data before being able to carry out the project. 4. OBJECTIVES The aim of this phase of the project was to model and integrate, within a GIS, the different elements of the water cycle in the region of Navarre, taking into account the industry standard data models and the regional, national and European policies. In order for this aim to be achieved the following objectives were defined: - Generation of the hydrographic geodatabase (SIAN). - Generation of the water supply network geodatabase (SIAB). - Integration of data in both networks. - Compliance of the hydrographic geodatabase with the WFD requirements. - Development of the exploitation tools. - Diffusion in a Website of the information people are concerned about, according to the Århus Declaration. In this paper, attention is only paid to the first three objectives. Figure 1. Navarre in the world

3 4. METHODOLOGY 4.1. Generation of the hydrographic geodatabase (SIAN) To structure the information contained in the hydrographic layers, the ArcHydro data model, developed by a consortium integrated by ESRI and the University of Texas was chosen. This model uses the capabilities of a geometric network to integrate layers containing information about natural water systems (Maidment, 2003). Despite the fact that it is scalable and flexible, it has no references to groundwater features. ArcHydro models streams as edges and point features as junctions, and allows navigating through connected elements. Moreover, connection to existing hydrological and hydraulic models such as HECs and DHIs is feasible (Maidment & Djokic, 2000). Figure 2. Components of the model (Maidment, 2003) Every feature in the SIAN geodatabase (which includes rivers, springs, basins, stream and rainfall gauges, water quality monitoring sites, water bodies, dams, bridges and other structures) owns a unique identifier, just one of the concepts the WFD wishes to implement (Vogt, 2002). This identifier helps to maintain the relationship between time series and the spatial data. As a resume, the ArcHydro data model consists of five components: - Network - Drainage - Hydrography - Channel - Time series Concerning SIAN, most of the layers containing information suitable for the project were not of high enough quality to be directly integrated in the model, thus making a correction of the layers necessary. The following steps were carried out: - Correction of the streams feature class, in order to remove dangle and pseudo nodes. - Assignment of stream attributes, including stream name. - Correction of the digitizing direction, to better represent flow direction. - Assignment of the measure (M) coordinates, to help on linear referencing and avoid redundancy in the geodatabase. - Generation of the junction s feature class. - Generation of the geometric network.

4 Figure 3. Overview of the SIAN network over the DEM after correction procedures Generation of the water supply network geodatabase (SIAB) A great effort has been invested in developing a data model suitable for the purposes the water supply network had. After some brainstorming, it was decided to define a new data model based on previous experiences (GADA system) and the ArcHydro data model. Moreover, the data model takes into account that for budget purposes, the current and future networks exist at the same time within the geodatabase. The network includes features such as pipes, fittings, pumps, treatment plants, tanks, electric devices, telecontrols, water uptake, pressure head breaking casings, vents, outlets, meters and sampling stations. Figure 4. Overview of the SIAB network over the city of Pamplona (capital city of Navarre). As a resume, the SIAB data model consists of four components: - Planning - Budget - Network - Schemas

5 4.3. Integration between SIAN and SIAB Yet as both networks were generated in different projects with different purposes and criteria, the necessity to establish a relationship between them has been pointed out in the present work. From a user point of view, SIAN and SIAB integration looks quite intuitive and in a conceptual way it is (Velasco, 2003). On the one hand, SIAN includes spring and stream feature classes. On the other hand, SIAB includes water uptake (springs and streams) and outlet (return to streams) feature classes. Yet as integration looks immediate through a relationship class, it is necessary to first establish a maintenance protocol via Workflow techniques or even the use of an ArcSDE working environment. This is necessary because maintenance of the networks is carried out by different agencies, thus making communication between them necessary. 5. CONCLUSIONS Although both networks view water from a different perspective, the capabilities derived from their data models are similar: SIAN allows to trace features and carry out spatial analysis, whilst SIAB allows to trace features and carry out spatial analysis, also to carry out network schemas, network planning and budget. After this effort to determine location and integration of water related features, further development of the project includes time series changes on water quality and quantity - and modeling of water channels, in such a way that hydraulic analysis is allowed within SIAN. Moreover, once the communicational issues between SIAN and SIAB are resolved, the information of quantity and quality of water in the natural network and the same information in the distribution network can be integrated in order to assure civil, industrial and agricultural activities without over-exploiting the natural resources. As a conclusion of this document, the suggested aim of the water agencies in Navarre should be to model the whole cycle of water -including rainfall, groundwater, urban distribution and treatment networks - in order to better manage the growing demand of fresh water with the high enough quality that the European population asks for, also to allow for hydrological (i.e. rainfall-runoff transformation) and hydraulic (i.e. flood areas) modeling. In order for this to be achieved, further research and consultancy tasks are needed to solve technical obstacles and communication issues between different agencies. REFERENCES Booth, B.; Crosier, S.; Clark, J.; McDonald, A. (2002): Building a geodatabase, ESRI, Redlands, USA, 460 p. Burrough, P. A.; McDonnell, R. A. (2000): Principles of Geographical Information Systems, Oxford University Press, New York, USA, 333 p. Heywood, I.; Cornelius, S.; Carver, S. (1999): An introduction to Geographical Information Systems, Pearson Education Limited, Harlow, UK, 279 p. Kraak, M. J.; Ormeling, F. J. (1999): Cartography: Visualization of spatial data, Pearson Education Limited, Harlow, UK, 222 p. Maidment, D. R. (2003): ArcHydro: GIS for Water Resources, ESRI Press, Redlands, USA, 203 p. Maidment, D. R.; Djokic, D. (2000): Hydrologic and Hydraulic Modeling support, ESRI Press, Redlands, USA, 216 p. Navarre government, (2004), Stanczyk, S.; Champion, B.; Leyton, R. (2001): Theory and Practice of Relational Databases, Taylor & Francis, London, UK, 253 p. Velasco, X. (2003): Gestión integral del agua en Navarra, draft of Trabajos Catastrales S.A. Vogt, J. (2002): Implementing the GIS elements of the Water Framework Directive, Institute for Environment and Sustainability, Ispra, Italy, 172 p. Zeiler, M. (1999): Modeling our world: the ESRI guide to geodatabase design, ESRI Press, Redlands, USA, 199 p.