Modeled Impacts of Surface Coal Mining on Dissolved Solids in the Tongue River, Southeastern Montana

摘要

A computer model has been developed for assessing potential increases in dissolved solids of streams as a result of leaching of overburden materials used to backfill pits in surface coal-mining operations in southeastern Montana. The model allows spatial and temporal simulation of streamflow and dissolved-solids loads and concentrations for user-defined plans of surface coal mining and agricultural development. The model specifically addresses the Tongue River from the Tongue River Dam to Miles City, Montana and its three major tributaries. Provision is made to simulate releases from the present Tongue River Reservoir or the increased releases expected from a larger dam and reservoir proposed as a replacement for the present Tongue River Reservoir. The model routes an input quantity of streamflow and dissolved solids from the upstream end to the downstream end of a stream reach while algebraically accounting for gains and losses of streamflow and dissolved solids within the stream reach.