Objective Of The Services
Esteio was hired by Eletronorte to perform mapping services over approximately 600 square kilometers, as well as topobathimetric services along 120 linear kilometers, in the reservoir area of Samuel Hydroeletric Power Plant, using LIDAR technology.
The main objectives of this service are to define cross-sections of the reservoir botton, to satisfy ANEEL Resolution number 396 (1998, Article 20), as well as to define the reservoir area in the four municipalities affected, which are: Itapua do Oeste, Candeias do Jamari, Cujubim and Alto Paraíso.
Location
Service area is located in the basin of the Jamari river, in the state of Rondonia – Brazil, about 50km from the city of Porto Velho and 25km from city of Candeias do Jamari.
Flight Plan
Prior to commencement of services, a detailed flight plan was made for the LIDAR flight to be run over the area. The flight plan was made based on a graphic file containing the boundaries, provided by Eletronorte.
The flight was planned in order to obtain mapping products compatible to the service requirements. The flight plan was made providing starting and closing flight strip points coordinates, distance between the flight strip axes and flight height.
Flight Execution
The flight was executed according to the occurrence of favourable atmospheric conditions. We emphasize that, due to the occurrence of clouds during the day, some flight strips were performed during the night, during nebulosity free periods.
The flight crew worked together with the Survey Team, as this one occupied reference base stations during the LIDAR flights, with GPS equipments.
Flight crew used as base the Airport of Porto Velho (Aeroporto Governador Jorge Teixeira de Oliveira).
Topography
The topographic services were responsible for the location of the starting and closing benchmarks for the topobathimetric sections, as close as possible to the 90 meters elevation, as well as the determination of the reference base stations, for the LIDAR flight georeferencing.
Geodetic and topographic services were referred to the geodetic benchmarks of IBGE (national geodetic authority), also to the leveling line along the BR-354 road, between Porto Velho and Ariquemes.
LIDAR And DTM Processing
After the GPS post-processing, LIDAR data raw was processed. For this processing there was the insertion of equipment calibration parameters, information about relief and vegetation type, and equipment configuration.
DTM classification was performed with TerraScan LiDAR Data Processing package, based on classification parameters according to terrain inclination. Lidar above-ground points were separated according to geometric distribution, altitude and laser pulse return intensity.
Topobathymetry
The planned sections were performed by topography at the dry areas of the reservoir and by bathymetry at the wet areas.
The bathymetric survey through echobathymeter was performed to recognize the lake bottom where the level of the water does not allow its measurement by conventional topography.
22 sections were performed, the first 9 sections in the reservoir area and the others in the Jamari River. All the sections totalized 130 kilometers.
Bathymetry Processing
The sections measured in the field were processed at the Office. Topographic and bathymetric surveys were unified, in order to consolidate unique sections.
Using the Hypack software it’s possible, not only real-time navigation over planned sections, but also correlate measured depths to GPS obtained positions.
Final Maps
Lidar-generated composition maps were produced, which are hipsometric images aggregated to intensity values of each Lidar point.
This hipsometric image has a color scale starting blue, used to indicate lower elevation points, and finishing red, which indicates higher elevation points, according to map index.
Over such images the elevation contours were printed, according to Eletronorte concern.
Topobathymetric Section Profiles
To represent topo-bathymetric sections, georeferenced graphics were produced for each continuous profile, representing progressive distances, remarkable points, water level and others features of concern.
Fluvial parts and dry parts were highlighted, as well as water level and its date of acquisition.