PARENT SESSION
Poster Session 39: Late Breaking and Newsworthy Posters
Friday, August 12, 8:30 AM - 10:30 AM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Turbidity as a surrogate for estimating suspended sediment loads.

Balbach, Harold^*,1, Sharif, Muhammad¹, Engel, Bernard², ¹ US Army ERDC, Champaign, IL, USA² USDA-ARS, West Lafayette, IN

ABSTRACT- Numerous land-disturbing activities result in elevated concentrations of suspended sediments in streams as a result of accelerated erosion. These suspended sediments can compromise biotic integrity, degrade water quality, decrease habitat quality, and result in downstream sedimentation. Development and construction projects are the most obvious sources, and ones which both regulatory agencies and community groups wish to monitor. In the Army installation context, these are often the result of training and testing activities. Nevertheless, there is currently no practical method for directly measuring either suspended sediment concentration (C_sed) or the transported sediments in such water bodies. In our study, turbidity (T_NTU) and C_sed data were analyzed in the laboratory for representative soils of Fort Benning, Georgia. Samples were collected to represent a wide range of land uses including firing ranges, training areas, and riparian buffer zones. Results showed highly significant correlations between C_sed and T_NTU with linear regression equations of the form {C_sed = f (T_NTU)}. A network of sediment-turbidity monitoring stations has been established on the installations major streams to calibrate the empirical model derived under laboratory-controlled conditions. These results strongly suggest that turbidity can be used as a surrogate to estimate suspended sediment concentrations in instances where water quality conditions must be evaluated, such as the development of sediment TMDLs and their control effectiveness. This is also important where logistical and/or financial constraints make a program of continuous stream sediment monitoring impractical. Since turbidity can be easily and inexpensively measured, such measurements may be used with confidence to estimate real-time continuous concentrations and loads of transported sediments in streams and creeks on Army training lands as well as in relation to any type of construction and development activities.

Key words: sediment load, turbidity, soil loss, monitoring soil loss