2014 Progress Report: Role of land use and BMPs in reducing the effect of extreme magnitude events on sediment and pollutant transport in the SE US Coastal Plain and Mississippi Alluvial ValleyEPA Grant Number: R835186
Title: Role of land use and BMPs in reducing the effect of extreme magnitude events on sediment and pollutant transport in the SE US Coastal Plain and Mississippi Alluvial Valley
Investigators: Hatten, Jeffery A
Institution: Oregon State University
EPA Project Officer: Hiscock, Michael
Project Period: April 1, 2012 through March 31, 2017
Project Period Covered by this Report: April 1, 2014 through September 28,2015
Project Amount: $363,258
RFA: Extreme Event Impacts on Air Quality and Water Quality with a Changing Global Climate (2011) RFA Text | Recipients Lists
Research Category: Global Climate Change , Air Quality and Air Toxics , Water and Watersheds , Climate Change , Air , Water
The overall objective of this research is to determine the role of best management practices (BMPs) and land use decisions in affecting water quality in the face of extreme events and climate change. Two objectives have been developed to guide this research:
Objective #1: Determine the capacity of BMPs to reduce large event-caused delivery of sediment in a lake with a small agricultural watershed in the Mississippi Alluvial Valley (MAV). Our working hypothesis is that the efficiency of BMPs at reducing sediment and pollutant yield will decrease with increasing storm magnitude.
Objective #2: Determine the role that BMP development and land use decisions have had on event-associated sedimentation rates in a lake with a large watershed. We hypothesize that in a large watershed (Loon Lake watershed in the Oregon Coast Range), the response of sedimentation to BMP and/or Oregon Forest Practices Act implantation will be much slower as a result of large stores of sediment deposited as a result of historical land use in locations proximal to the river. The flux of sediment from these sources is likely to be affected by a change in river discharge as a result of climate change.
The planned objectives for this period were to focus on sampling, processing, and analysis: This objective included collecting cores and processing samples for both the small and large watersheds. In September (2013) we collected 16 cores from several locations within Loon Lake. We chose to focus our analytical efforts on cores collected from the deepest part of the lake. This location included two 6+ meter long Nesje cores (3-inch diameter) and one 2 m long gravity core (4" diameter). We used the Nesje cores to characterize the long-term sedimentation patterns and sediment characteristics in this watershed. We will be able to compare presettlement, post-settlement/pre-regulation, and post-settlement/post-Oregon Forest Practices Act (OFPA). We have analyzed the Nesje and gravity cores for radio isotopes (210Pb and 137Cs), C&N abundance, particle size distribution, stable isotopes (13C and 15N), and dated materials in the deeper sections using 14C.
To accomplish this work, we have employed an MS student (Kris Richardson) who did a remarkable job coordinating the coring, processing, and data analysis. Kris will defend her MS thesis this December (2015). In addition, Francisco Guerrero-Bolano, a Colciensas fellow from Columbia, is working to take the lead on the biomarker and stable isotope analysis. Kris, Franco, and Dr. Hatten (PI) have made several presentations to local and national audiences. We also have included an Honors College undergraduate student on the project – Emily Day.
We have received a core collected from Beasley Lake (small watershed) in the MAV from Daniel Wren, a scientist at the USDA-ARS National Sedimentation Lab. This core has been CT scanned and analyzed using Geotek MSCL-S and Gamma Density sensor. This core has been sub-sampled and we have completed all particle size analysis, radio isotope (137Cs and 210Pb), and stable isotope (13C and 15N) analysis.
Progress Summary:We currently are analyzing the sedimentation rates, elemental distributions, and particle size distributions. Preliminary results include:
- We analyzed the sediment accumulation rate in the recent portion of our sediment cores (1939-2013) and found evidence that the Oregon Forest Practices Act (OFPA) was significantly (p=0.0028) associated with lower sedimentation rates (Figure 1). Pre-OFPA sediment accumulation rates were 0.70-0.93 g cm-2 yr-1 (95% CI) and post-OFPA rates were 0.52- 0.71 g cm-2 yr-1 after accounting for climate. This suggests that OFPA was effective at reducing sediment influx from the surrounding watersheds.&
- We compared the pre- and post-OFPA period to the pre-settlement period (550-1780 AD) and found that the pre-settlement period had a lower sedimentation rate (0.41-0.44 g cm-2 yr-1) (Figure 2). The differences in sedimentation rate suggest that there may be other factors resulting in high sedimentation rates in the post-OFPA period. In the coming months, we will examine several working hypotheses that may explain the differences in sediment accumulation between the pre-settlement and post-OFPA period. This line of questioning will have us digging deeper into the structure of the sediment within the cores as well as using stable isotopes and biomarkers.
- Kris Richardson will defend her thesis this December (2015) examining the sedimentation rates pre-settlement, pre-OFPA, and post-OFPA. In addition to the Key Findings above, she will:
- Examine sediment accumulation rate in more detail in the pre-settlement portion of the core to determine if there were any periods of sedimentation equivalent to that of the most recent 74 years.
- Quantify harvest pressure on the sedimentation rates in Loon Lake. We are working with a major landowner to acquire historical harvest records.
- Examine the event layers to determine how extreme magnitude events have been influenced by land use practices.
- Determine the CuO oxidation products (e.g., lignin and cutin products) of whole sediment samples in order to examine the mobilization and transport of sediment in the watershed.
- Begin data analysis of sedimentation rates in relation to BMP implementation in the Beasley Lake watershed.
- Examine the source of sediment using elemental and stable isotopic composition of sediment within the core.
- Attend the fall meeting of the American Geophysical Union in order to present the current results from this project.
- Pursue additional funding to examine the other cores collected from Loon Lake and connect lake-wide sedimentation rates to a watershed scale water and sediment budget.