The Anatomy of a Storm Pulse: An Example from the Clear Creek, IA Site of the Intensively Managed Landscape - Critical Zone Observatory (IML-CZO)
Abstract
Streams and rivers are conduits for the transport of sediment and organic carbon (OC) eroded from landscapes. A large portion of the transport occurs during short-lived (hours-days) storm events, especially in small to moderate sized watersheds in temperate climates. There are multiple potential sources of sediment and OC to the fluvial system and they are expected to vary through an event. The goal of this project was to deconvolute a storm pulse in terms of changing sources as a function of time within a small agricultural stream network in the NSF-sponsored IML-CZO (EAR-1331906). The Clear Creek watershed is 270 km2 and is dominated by corn-soybean agriculture. Water samples were collected prior to, during and after 6 storm events during the 2014-2016 period at up to three stations on the creek and at two tile drain outlets. The suspended particulate load was isolated via filtration and characterized by C, N elemental and stable isotope analyses.
Sources of fluvial material include in-channel primary and secondary production, surface soils, banks, and tile drains. Storm pulses of sediment could be resolved into relatively sharp peaks preceding or superimposed over broader peaks. The sharper peaks were associated with heavy precipitation in some situations. They are hypothesized to have been derived from a local surface source. The broader peaks coincided with the rise and fall of the hydrograph and likely contained a bank erosion component. The broad peaks are inferred to be the result of the integration of distal upstream sources as the pulse moves downstream. Algal debris was most evident pre-storm when turbidity was low. Tile drains had the potential to be important contributors of particulates during the return to base flow after the event. Peak deconvolution revealed that the complexity of the storm pulse increased with travel downstream as tributaries fed the main stem with their own temporal sequences of materials.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMEP32B..05B
- Keywords:
-
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCESDE: 1815 Erosion;
- HYDROLOGYDE: 1862 Sediment transport;
- HYDROLOGYDE: 1879 Watershed;
- HYDROLOGY