Hydraulic and Particulate Matter Retention in a 3rd-Order Indiana Stream

Abstract

Retention of water and particulate organic matter (leaves and wood) was studied experimentally in Juday Creek, a 3rd-order woodland stream in northern Indiana. Fluorescein dye and 1500 Ginkgo leaves were released into each of nine 50-m reaches classified into three reach types based on the quantity and arrangement of large woody debris (LWD). Reaches with accumulations of LWD (debris dams) retained water, based on nominal transport times, 1.5-1.7× longer than the channelized (non-woody) reaches with minimal LWD. Reaches with LWD located only along channel margins (edge wood) were intermediate in hydraulic retention. Average leaf travel distances increased from 109 m (debris dam) to 125 m (edge wood) and 168 m (non-woody) as the amount of reach LWD decreased. Fifty wood dowels were released into debris dam reaches and non-woody reaches. Wood traveled an average of 14 m in debris dam reaches compared with 183 m in non-woody reaches. The most important retention structures for leaves and wood, besides debris dams, were stream margins, roots of riparian vegetation, sticks, and single LWD pieces. Although mid-western streams typically have much lower LWD loads than many coniferous forest streams, such LWD provides important sites for organic matter retention and processing.