"Proceedings, Federal Interagency Workshop,
"Sediment Technology for the 21'st Century,"
St. Petersburg, FL, February 17-19, 1998"

Development of an Suspended Sediment Measurement System (SSMS)

By Dan Gooding

Pre-Proposal

Issue/Problem

A device has long been sought after to measure the full spectrum of suspended solids concentration and particle size and at the same time endure the hostile field environment. Ideally such a device should need little or no calibration and easily operated with limited instructions. With the recent advancements of high-resolutions digital cameras, PCI frame grabbers with filters, along with the increasing computing power of PCs, we can capture in-stream images at a faster rate and compute far greater amount of data for digital images as in the past. Digital signal processing with multiple images along with an established algorithm can instantly produce in-situ stream concentration and complete size distribution down to 4 microns.

The technology can be used for a variety of other reasons such as the investigation of stratified flows, sedimentation jets and plumes, velocity measurements, flow structures, concentration measurements, and particle size, just to name a few. For simplicity this proposal will focus on two by-products of this device, concentration and particle size.

Beneficiaries

Both government and private agencies interested in environmental concerns or anyone interested with sediment transportation/movement in riverine, estuarine, and marine ecosystems.

Objectives

There are four basic objectives for the development; 1. Minimize cost by using much off-the-shelf instrumentation as possible; 2. Package the technology in a way to simplify operation for the users; 3. Minimize equipment exposure from water hazards resulting in expensive replacement costs or repairs; The only components subject to weather and immersed in water will be the lens, a photo-optical chip and a portion of the cable; 4. Develop the means for remote monitoring to accomplish continuous realtime, single point monitoring of a 24 hour period.

Approach

A two stage approach is recommended. The basic components will include 1) progressive area scanning CCD (charge coupled device) camera 3) lens and CCD chip 4) a light source 5) PCI frame grabber and filtering software. These are all standard pieces of hardware and can be easily purchased commercially. The PCI frame grabber and filtering software may only be needed for the prototype to develop an algorithm. A prototype will be designed and tested for laboratory applications. Incorporating this technology in the laboratory will greatly increase the throughput. Discrete samples can be placed directly into a cylinder or tube to give instantaneous size and concentration readings. Not only the speed of producing results will be a benefit but also samples will be easily analyzed in native water. After successful evaluation as a laboratory instrument the second stage can commence with a high degree of confidence with the development of a field sampler.

The lens, light, and CCD chip will be assembled and installed into a sealed canister. The canister will have the size and dimension of a one liter sample bottle. The concept is to insert the canister into a depth integrated sampler such as the D-77. The sampler nozzle will line-up with the canister orifice that leads into the analyzing tube and exits through the exhaust port of the sampler. With little or no modification to the depth integrated sampler, the sampler will interchangeably work with both a sample bottle or this proposed electronic device.

Funding

Up-front funding for developing the imaging prototype for both laboratory and field applications will be < 20k for equipment purchases. Approximately man year is needed for development for the laboratory version and additional man year for a field prototype.

Principal Investigator

Dan Gooding, Cascades Volcano Observatory, Vancouver, Washington


upWorkshop Contributions


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