ABSTRACT
Water quality impacts from floodplain gravel mining are a subject of public controversy. Specifically, the nature of thermal impacts from off-channel operations are poorly understood. This paper describes the characterization of surface water and groundwater heat flow in a large off-channel floodplain gravel mining operation in the Pacific Northwest. The final project data set was analyzed with methods ranging from simple empirical calculations to geostatistical modeling. Regional characteristics of the surface water environment were evaluated using simple calculations of downstream thermal gradient. Variography of temperature records from pond thermal strata demonstrated the pond’s response to thermal characteristics of the regional surface water system Selective two-dimensional variography of the surface water heat flow system exhibited consistent semi-variogram forms across widely different temperatures and conditions. Advances in monitoring and analysis, such as variography in a Bayesian framework, could be implemented for future monitoring programs.
