Integrating historical topographic maps and SRTM data to derive the bathymetry of a tropical reservoir

Abstract

This paper proposes a cheap and fast method for est imating the bathymetry of hydroelectric reservoirs. Brazil has more than 30 l arge hydroelectric reservoirs with volume exceeding one billion cubic meters. The hydroelectric sector is responsible for 97% of energy generation being the largest hydroele ctric park in the world. These dams, however, cause a series of environmental, social an d economic impacts, which need to be monitored. Among the variables affecting the env ironmental impact posed by reservoirs, depth has a key role because it acts on the aquatic system hydrodynamics. Reservoir depth distribution, the bathymetry, is al so a fundamental factor controlling physical-chemical and biological properties of the system. In Brazil, the acquisition of bathymetric information for the large reservoirs, h owever, is not a simple task, because: 1) most of the topographic maps available in the ar ea covered by the lake have very small scale (1:100 000 and smaller); 2) larger char ts are property of the hydropower companies and are classified; 3) the size of the re servoirs prevent the use of bathymetric surveys due. The challenge therefore is how to comb ine the use of low precision topographic charts from the period previous to rese rvoir filling, SRTM data to obtain a bathymetric map which could be used for planning echo-bathymetric missions so as reducing both cost and time of data acquisition and processing.