Sediment balance and flushing flow analysis: Trinity River case study

Abstract

The use of sediment yield as one aspect of a flushing flow analysis is explored in a case study of the Trinity River in northwestern California. Understanding sediment balance can help in the development of a flushing flow need, but hydraulic analysis must also be done. The most important flushing flow need for the Trinity River is to increase the Trinity River flows when flows in Grass Valley Creek and other tributaries draining the Shasta Bally Batholith are high. The goal is preventing deposition of sand and fines. These flows should be followed by clear-water flushing (i.e., flushing flows when the tributaries are not high) to remove fines and sand from the stream bed.