Dalles Dam Survey

Introduction:

From 27 September through 11 October, NORBIT and SEAHORSE Geomatics performed system tests, modifications and finalisation of a “Release 2.0” software/firmware for the Wideband Bathymetric Multibeam System, WBMS.

During the test and validation, a survey of the Dalles Dam area was conducted to verify complex bottom conditions as well as range capabilities of the system

Sonar system

NORBIT began the evolution from their conformal array WBMS Forward Looking Sonar system into a “market game-changing” bathymetric multibeam sonar system in late 2011. This system offers the benefits of a conformal receiver array, which maintains the same narrow beam angle at nadir throughout the swath. NORBIT celebrates the first conformal array sonar system to be introduced to the industry in more than a decade.

Survey Results - Rervoir

Complex Bathymetry Detection Capability – The Dalles Dam Reservoir

A hole found just above the Dalles Dam is one of the deepest locations on the Columbia River near Portland. The vessel transited about 80 miles and went up two locks (Bonneville and The Dalles) to reach this place. The bathymetry of this area is complex, with smooth flat areas and sudden deep canyons.In addition, the lock chamber was also surveyed. This area is highly reflective due to the presence of concrete and steel materials below the water.

DTM of Dalles Dam — Depths below waterlevel are up to 95m deep. The old ship canal can be seen to the east – this was used prior to the building of the dam by vessels transiting around the waterfall.

Units: Meters Profile Slice Width: 50cm Profile shows generally very good agreement of multiple survey lines even along the steep walls of the former river before becoming a reservoir.

Units: Meters Profile Slice Width: 0.55m The Dalles Dam: Forebay. Fresh Water – Columbia River Columbia River has heaviest flow of any North American River draining into the Pacific Ocean. Processed Cleaned Data

Survey Results - Lock Chamber

The Dalles Dam – Lock Chamber – Acoustic Multipath Environment

Concrete walls, a mix of concrete, rock, and steel bottom. Clean articulation of the diffuser bars

Surveying inside Dalles Dam Canal — Surveying inside the Dalles Dam Canal

Left: Solid bottom detections even over steel plates - Right: Clean detection even at the bottom corners of the concrete walls.

Conclusion:

Sonar demonstrated excellent range capabilities, measuring areas more than 90m deep.
Excellent detection of a very complex bottom, notice deep canyons in the dam where the river originally was
Excellent performance against hard vertical structures in the more than 100-feet narrow lock, concrete/steel, very difficult environment