Author(s): Shivansh Shrivastava; Michael Stewardson; Meenakshi Arora

Linked Author(s):

Keywords: No Keywords

Abstract: The water and nutrient exchange at sediment-water interface (SWI) also known as hyporheic exchange (HE) is a key process that underpins stream ecosystem functioning. However, there is only a limited understanding on influence of other environmental processes on HE. In this work, we show that physical clogging and bioturbation are crucial processes which can alter hyporheic flows across SWI, thus altering the residence times of water and solute in hyporheic zones (HZ). Fine sediment clogging in coarse streambeds can substantially reduce the exchange process while bioturbation can potentially lead to enhanced exchange. We performed dye tracer experiments in laboratory flumes to simulate hyporheic upwelling and downwelling using sand as bed material, clay as fine particles and, Lumbriculus variegatus (also known as blackworm) as sample bioturbators. We monitored exchange by measuring change in dye concentration in water column over time with four different experimental flume conditions-a) sand alone b) sand& clay c) sand, clay& worms and d) sand& worms. The results indicate that fine sediments and bioturbation can significantly influence the exchange rates. The alteration of hyporheic exchange flows and residence times in sub-surface sediments can affect overall stream water quality.

DOI:

Year: 2018