AN INTEGRATED INFORMATION SYSTEM FOR THE SASS/NWSAS

The component "data Bases - SIG", initially foreseen to gather the available information in the three countries and necessary to the realization of the numeric model, was made to settle a real structure of compilation, analysis and information management relative to the NWSAS basin evolving thus toward a concept of "integrated information system".

This approach was necessary because it permits:

• to capitalize collected information and thus to re-use them for future actualisation operation
• to homogenize procedures of management and data treatment through the three countries and make than possible information exchange
• to gradually prepare a technical and organisational system of consulted management of the shared aquifer system

The realisation was justified on four fundamental options :

• an efficient methodology conception that led to the setting up of an integrated information system, lasting and evolutionary based on the relational model as well as the technology, a thing permitting the integration of the GIS.
• an approach encouraging the active countries involvement in all realization phases of this system: conception and implementation, data collection and validation.
• a progressive setting up of a device permitting a regular information updating as well as data exchange between the three countries.
• a total control of the system by the qualified services of the three countries.

Its implementation required four stages:

• analysis of the existing information at the level of the three countries and choices of the organizational solution considering the project objectives, the countries specific needs and the present technological tendency (material and software);
• conception of the information system and description of the chosen computer solution in collaboration with countries: architecture of the common data base, identification of GIS layers, harmonization of the codification, definition of mode of treatment,
• implementation of the data base and the GIS: installation of equipments and software, implantation of the data base and the GIS, existing heterogeneous data transfer in the three countries. The three teams were initiated to the utilization of the acquired software (SGBD, GIS, utilitarian of spatial analysis);
• integration of the three components of the geographical information system in the BD, establishment of the links GIS-model, development of transfer modules DB-models, (historic by point or by grid)

Such an action permitted to gather a considerable mass of information (more than 7000 water points, an abstraction historic and a piezometrical historic that cover the period (1950-2000) regrouped within a homogeneous and coherent data base.

In the same way, tools of data analysis have been developed to criticize, to detect anomalies, incoherence and have been provided to the numeric model valid information. These tools regroup request, statistic treatment and spatial analysis with the help of the GIS.

The NWSAS information management system is made of three main component:

• a data base ACCESS stemmed from a data model (MCD) that integrates the necessary information to the NWSAS project as well that those specific to countries.
• a GIS achieved with the help of the software ARCVIEW grouping the whole layers necessary to the survey:
  • cartographic map
  • DTM
  • administrative limits and main agglomerations
  • geology
  • hydrogeology
  • hydraulic parameters

An original interfacing that permitted the establishment of the links DBS - GIS - numeric model whose main application is the automatic preparation of entrance files to the software of modelling "PM5"

The links DB - GIS are expressed by :

1. the integration of the descriptive data of the geographical layers in the DB in order to be able to use them in the same requests outside of the GIS. Redundancies are thus avoided, information being stocked to only one place;
   
2. the creation of GIS layers for the whole data susceptible to be mapped or to make the object of spatial requests: at the time of the conception of the DB, an inventory of these entities has been made (abstraction zone, aquifers, administrative units,…) so all request achieved on the DB can, without difficulty, make the object of a thematic cartography.

The basis unit being the water point, information managed by the DB are regrouped in five categories:

• identification - water points localisation
• Spatial Units (administrative and physical limits)
• historic (exploitation, piezometry, quality) , hydraulic parameters.
• geological and lithological Data
• information of link with the numeric model (grid, relation points water - grid).

It is possible to insert other information. It is sufficient for this to respect the elementary relational basis rules and to keep the core that constitutes the common data base: structure, codification,...

This opening possibility guarantees the system lasting and constitutes the main element of the consultation mechanism (data actualization and decisional tool).

Two modes of data entrance are possible:

• by application: where are achieved controls of validity and consistency

• by transfer of EXCEL files

This mode of data entrance used at the time of the initial collection operation is made according to precise canvases that permit their automatic transfer in the DB. This mode presents an advantage for certain users because of the capture easiness in a familiar environment. Every sheet of the Excel folder corresponds to a table of the common data base.

The data base is conceived to function in an environment multi - user. For that, the system includes a part "Data" to be shared and installed therefore on a server and a part "Programs" that is executed from the client stations.

The access to data is regulated: every DB user has an account and a password. Four groups of users have been created:

• administrators: they have authorizations permitting up date some tables "Systems" and to manage accounts users (creation, modification, suppression)
• entering data: this category possesses privileges to capture and modify data (actualization, possible mistake correction).
• models preparation: team in charge of the capture and updating of data serving to the calibration or simulations of the model PM5 (grid, layers PM5, feeding,…)
• consultation: this users category has only the authorizations to visualize a restrained information part in the DB

The whole collected geographical data through various sources has been homogenized and has been converted in one same projection that is the Lambert South Algeria.

Layers of the GIS so organized during the project are to the ARCVIEW format. The descriptive information connected to these layers are stocked in the DB tables in order to respect the principle of no redundancy of data in the global system.

In order to assure the DB - GIS links, shps files and the corresponding tables containing the descriptive data, possess the same identifying.

These links permitted to achieve the indispensable treatments for the control and the validation of data:

• filling the lacking data of the data basis (wilaya, basin,…). This could be viable only if coordinates are valid.
• calculation and thematic value affectation (sum, average, account,…) spatial unities.
• automatic synchronization between the water points table and the GIS layer "water points": there is automatic updating of the GIS layer to every coordinates modification or addition of new water points.

Developed tools during the project realization (calculation modules, statistical requests, crossing analysis requests,..) have been regrouped within an unique package baptized "SAGESSE" (System of help to the Management of the Septentrional Sahara Waters).

In addition to the fact that it constitutes an excellent instrument of visualization, of appropriate up to date and of data treatment, SAGESSE includes an original module of data preparation for the software PM5 freeing then the user from the hard task of manual historic constitution (abstraction, feeding) by model grid.

This functionality provides to the user more liberty to modify without constraint the grid's properties (size, orientation, number).

The architecture of SAGESSE has been conceived around specific developments in VBA permitting to facilitate the navigation in the DB with cartographic visualization possibility without leaving the ACCESS environment.

The interfacing of navigation that is at the same time the main menu, offers the possibility to visualize in a numeric or cartographic way.

The more known GIS functions (zoom, flap, layers control, labels display, selection by click,…) were clarified. What allows users not to leave the DB environment to achieve these tasks.

On the organizational plan, a mechanism of data update to the different steps of intervention (regional services, administrations head offices, NWSAS office) should be settled. This device, based on formalized procedures and tasks distribution between the NWSAS team and those of countries, will constitute an important stage for the future implementation of a consulted management cell to the scale of the basin. Three treatment levels have been defined:

1. the decentralized services, in charge of the existing data control, the proceeding to the complementary data collection, to collect and capture some new information;
2. the national services: that manage the NWSAS area data base and look after the general consistency of information;
3. the NWSAS team: that assures the cohesion of the data coming of the three countries and treatments on the whole basin, and guarantees the setting up of a common data base at the NWSAS level (that will be able to become the future DB of the consulted management structure).

Distribution of water point by countries and aquifers

Number of water points by type

Number of water points with hydrodynamic characteristic

Number of water with history

Setting up of local data bases

The realization of the local sub-models requires some compatible data structures with the common data base achieved during the project first phase and integrate the required new data by the scale and the resolution needed by this local level.

Some supplementary information have been integrated from the common BD to structures of this local data base. We can mention as an example:

• socio-economic data
• more precise data on users
• information on superficial waters

This survey also foresees the automatic passage of this local level toward the SASS regional level.

Table of incurred actions for the setting up of the IS