POSSIBILITY OP HELICOPTER USE IN SOUNDING SURVEY FOR HYDROGRAPHIC PLANS OP MOUTHS NAUTICALLY UNKNOWN

Reference is made to the method that it was necessary to resort to for the first complete hydrographic survey of the Cuama mouth on the Zambezi delta,where the plans for the economic development of the Zambezi Valley foresee the need for the establishment of a fluviomaritime harbour. Thi3 corresponds to the execution of sounding by means of a direct intersection method (shore controlled survey), using helicopters for the transportation of the echo sounder. The operational techniques for sounding with helicopters and localization of the points sounded are described, indicating also the equipment and personnel required for such operations. The results obtained through two hydrographic surveys carried out in 1962 and 1963 are indicated and analyzed, examining the technical worth of the method, its efficiency, costs and safety, as compared to the classical sounding methods. Further, reference is made to the possibilities for improvement offered by the method being described and to the circumstances under which it has been applied, taking into consideration the results obtained during the trial sounding operation.