September 30, 2010 -- The Brazilian National Water Agency (ANA) presented on December 9th 2009 the Atlas for Urban Water Supply for metropolitan areas, for regions NE and S Brazil. According to the Executive Abstract of the Project, distributed during the release event in Brasília and available on the site of the Agency, its result is the consolidation of a lengthy diagnosis and planning work in the sector of water resources and sanitation in Brazil, focused on the guarantee of water offer for all cities in the country.
The studies in the Atlas include population forecasts and demand estimates, evaluation of sources referring to water availability and quality, diagnosis of water producing systems and a proposition of technical alternatives for the water supply until year 2025.
GEOAMBIENTE was one of the companies under contract to execute this work. It was responsible to develop and implant at ANA the Atlas GIS, on Web and Desktop environments and supporting all phases of the studies performed.
For this work data were stored at an Enterprise Geodatabase, using ORACLE with the extension ORACLE SPATIAL and the spatial manager ESRI ArcSDE. The objects from ORACLE SPATIAL complied with the storing pattern Simple Features Specification (SFS) from Open Geospatial Consortium (OGC).
GEOAMBIENTE developed the Atlas Systems (Atlas South Brazil, Atlas Northeast Brazil and Atlas from Metropolitan Areas) within an ESRI environment, Microsoft.NET platform with NHibernate and Spring.Net, aiming modulation and ease of maintenance during its evolution.
The GIS ATLAS Desktop is a powerful tool to evaluate the availability and quality of surface and underground water resources. It is constituted by the following modules:
● Cadastre: it includes the cadastre of studies of demographic projections, demand estimate, percentage of urban population attended by treated water, and sewage systems, Sewage Treatment Stations (ETE), exploitable reserve of aquifers, superficial and underground sources and the water production systems.
● Diagnosis/Management actions: it allows the diagnosis of water sources related to the water availability and quality, as well as the evaluation of the capacity and adequacy of the treatment processes of water producing systems presently, in 2015 and 2025. This module also allows the proposition of management actions for the maintenance of systems and water sources in operation.
● Alternative: helps to propose alternatives to the choice of water sources, implantation of production systems or adequacy on the capacity of the existing systems, implantation of ETEs or improvement of already existing ones to remedy the deficiencies diagnosed on the water supply to populations.
At the evaluation of availability of superficial water sources, the GIS ATLAS Desktop has tools which calculate the effective superficial hydrous availability. This availability is calculated considering the imported and exported water flows (transposition among river basins), the granted use, the return flows of cities and the flows of urban demand from catchments of water producing systems upstream of the catchment. After the inclusion or change of a catchment, the GIS re-calculates automatically the availability of catchments which would suffer an impact downstream.
As for the evaluation of underground water sources, the exploitable reserve of each aquifer was distributed proportionally at the municipal territory, aiming to obtain the local water balance. The system got tools which calculate the effective exploitable flow, subtracting from this flow the granted uses of underground water, located within the municipality borders.
For the evaluation of the quality from water sources, the GIS Atlas Desktop uses pre-defined border parameters of gross water quality, at the section of water catchment for urban water supply. When the samples of these parameters are representative, they indicate how critical the quality of the water source is. If the samples are not representative, they are compared with the potential estimated loads, and those ones which are more critical define the vulnerability of the source.
As an alternative for the maintenance of the water sources and production systems with a vulnerable diagnosis, the GIS Atlas Desktop allows to propose management actions such as: reduction of losses in the water supply system, redistribution of flow among production systems, redistribution of flow among water sources, management of grants, use of reference flows with lower guarantees and review of the exploitable reserve.
The GIS Atlas Desktop allows to simulate the creation of new water sources for the supply, performing the calculus of the effective surface water and impact analysis on the water sources downstream. After the simulations the user can propose the use of a new source as well as the implantation of a new production system. The GIS Atlas Desktop calculates automatically the estimation of the cost from a work, considering regional price references, according to the State of the Brazilian Federation.
To improve the water quality of the potentially impaired water sources, the GIS Atlas Desktop allows to propose Sewage Treatment Stations, evaluating the impact of the reduction from potential loads estimated at the downstream catchments. In this case the system also allows the automatic estimation of the price from the work, according to a regional price reference.
Besides the Desktop system, GEOAMBIENTE also developed the GIS Atlas Web on the framework ESRI ArcIMS. The objective of the Atlas Web is to publish the results of the study in the Internet. It consists of cards from municipalities, water sources and production systems, as well as interactive maps and conclusive synthesis of the work. The GIS Atlas Web can be accessed at the site www.ana.gov.br/atlas.
The ATLAS systems are one of the most complete GIS already elaborated on the theme “Water resources and sanitation”, providing each municipality with the knowledge of its situation referring to urban water supply related to the availability of water sources (water quantity and quality) and on the size of the supply system, with technical proposals to supply its demands until 2025.
