Temporal sampling and discharge asymmetry in salt marsh creeks

Abstract

Studies of tidal flows in salt marsh creeks have shown velocity pulses on certain tides, although these have often been overlooked in considering temporal sampling designs for the measurement of discharge asymmetry. Velocity measurements for both spring and neap tides were taken at 5-min intervals at Bridge Creek in south-east Essex. The importance of temporal sampling interval in determining measured discharge asymmetry is examined using these data, integrating at intervals of between 5 and 30 min. The results indicate that sampling at 30-min intervals can underestimate discharge when velocity pulses on spring tides are not accurately monitored. Both under- and over-estimation of discharge on neap tides suggests that temporal sampling is also an important consideration when velocity pulses do not occur.