Expansion Plan
The Hydroelectric potential of a Hydrographic basin corresponds to the technical, economical and environmental potential that can be benefited from, in relation to a specific and determined configuration of an electric system, taking into consideration the operational power plants, the ones under construction or planned, and considering the multiple water applications scenarios.
The good quality of expansion plans depends on the accomplishment of coherent and homogeneous inventory studies, compatible in between, even when elaborated by several project companies or energy concession companies.
One of the attributions of ELETROBRÁS and ENEEL is to carry out the Brazilian electric system expansion plan.
This plan is developed in three levels: long term (25 to 30 years – Stating priority basins), medium term (15 years – feasibility studies) and short term (10 years – basic projects).
Inventory Planning
The planning aims at the scheduling of the later stages of the Inventory Study. The information to be gathered at this stage includes cartographic, geological, geotechnical, hydrometeorologic, sedimentometric, environmental and cost data, of regional and local nature.
The analysis of these data generates parameters, restrictions and factors, which allows the selection of the probable places for obstructions, the proposition of alternatives for fall splitting, the estimation of the energetic potential and the formulation of the work plan with its schedule and cost.
Rivers Surveyed
In order to meet the requirements for the obtaining of cartographic data, ESTEIO S.A. made use of the LASER scanning technology, using the ALTM – Airborne Laser Terrain Mapper from Optech Inc.
With such technology, surveys were carried out in Curuá and Maicuru Rivers in the state of Pará, and Arinos, Parecis, Claro and Patos Rivers in the state of Mato Grosso.
Around 1,200 km of LASER scanning strips were produced in the Curuá and Maicuru Rivers, resulting in hypsometric plans at the 1:5.000 scale and contour lines with a 5 m equidistance, adding up to a coverage of more than 840 km².
Around 1,000 km of LASER scanning strips were produced in the Arinos River. Alongside the Parecis Rivers about 465 km, Claro River with 370 km and Patos River with 195 km, adding up to 1.030 km of LASER scanning strips. In the same way, hypsometric plans were formed at the 1:5.000 scale and contour lines with 5 m equidistance adding up to a coverage of more than 1.400 km².
Characteristics
The region worked presented very dense vegetation coverage, not to mention the access difficulty by land, mainly in the state of Pará.
The installation of GPS points to act in the differential correction of the LASER data in the region of Pará was hindered by this reason, besides the local restrictions about the opening of clearings.
In Mato Grosso, in the Arinos River basin, the accesses were better and the choice of the points was facilitated, allowing good distribution of GPS bases.
The flight altitude for the LASER scanning varied between 1500 and 1800 m with a respective LASER sweeping width between 800 and 950 m. This survey was planned in order to allow a spacing of points in the terrain of the order of 1,5 m.
With the processing of the data, a penetration rate of 20% of the LASER beams could be observed in the blank areas of the vegetation, but there is no guarantee that these beams have reached the ground because of the vegetation density in these regions.
With the information of the processed data (E,N,h coordinates) of the points obtained and making use of the ERMAPPER software and of its tool GRIDING WIZARD, hypsometric images were formed; images in which the elevation difference is presented as a tonality difference.
These images are characterized by the representation of the topography and of the vegetal coverage in a graphic way which facilitates the visual interpretation, mainly regarding the identification of water bodies, since the LASER beam used is not reflected by water.
With the terrain points file (DTM – Digital Terrain Model) and with the Socet Set Software and its importation and manipulation tool of digital models and smoothing algorithms, the contour lines with 5 meters equidistance were obtained within the area of interest for the service.
The approximate tracing of the streams was done based on the interpretation of the hypsometric images, which represent in a very clear way the presence of water bodies.
These products represent the demand for cartographic information to assist the Inventory of Hydroelectric Potential. They describe an important stage of the Inventory, since they bring precious information about places of difficult access, lack of information, with environmental restrictions in a slender time.
Products
The results of the LASER scanning allowed the making of the following cartographic products: