Alan Kasprak - Background

In 2010, I completed a Master of Science degree at Dartmouth College in Hanover, New Hampshire. During this
time I was a member of Dartmouth's Earth Sciences Department, and I worked with Frank Magilligan. My research
focused on the interaction between anthropogenic land use and stream morphology at spatial scales ranging from
individual stream reaches to entire watersheds.

1. Remote Sensing of Large Woody Debris Sources and Recruitment Mechanisms
In-channel large woody debris promotes quality aquatic habitat through sediment sorting, pool scouring, and in-stream nutrient retention and transport. LWD recruitment can occur by numerous ecological and geomorphic mechanisms including channel migration, mass wasting, and natural tree fall, yet LWD sourcing on the watershed scale remains poorly understood. We have developed a rapid and spatially extensive method for using high-resolution light detection and ranging (lidar) elevation data to (1) constrain tree height throughout a watershed, (2) determine the likelihood for streams to recruit channel-spanning trees at reach scales, (3) establish whether adjacent tree fall, mass wasting, or channel migration may be the dominant mechanism for delivery of LWD, and (4) understand the past and future role of LWD at the watershed scale. We utilized this method on the 78 km long Narraguagus River in coastal Maine.
Collaborators: Frank Magilligan (Dartmouth College), Noah Snyder (Boston College),
Keith Nislow (US Forest Service)

2. Impact of Timber Harvest on Fine Sediment Delivery to Channels
Increased fine (< 2 mm) sediment in streams has been attributed to numerous factors, including anthropogenic activities. In this case, fine sediment production and delivery is believed to result from a loss of soil cohesion stemming from deforestation for timber harvest or road construction. Increases in fine sediments are particularly detrimental to spawning salmonids, and a great deal of research has been performed in high-gradient mountain streams of the Pacific Northwest. Comparatively less is known about the impact of timber harvest on fine sediment delivery to the lower-gradient streams of coastal Maine. We utilized field-based stream surveys (pebble counts, embeddedness measurements, shelter space surveys) augmented with isotopic analysis (210Pb and 7Be) to measure the quantity and temporal flux of fine sediment at various sites in the Narraguagus River basin in coastal Maine. These measurements were then correlated with the amount of area harvested upstream from each field site to determine the influence of timber harvest on fine sediment delivery.
Collaborators: Frank Magilligan (Dartmouth College), Noah Snyder (Boston College),
Keith Nislow (US Forest Service)

3. Estimating Sediment Accumulation Rates in a Flood-Control Impoundment
Dams have been constructed in the United States for numerous purposes, and their impact on biologic communities, riparian connectivity, substrate morphology, and flood regime have been well documented. Additionally, dams trap sediment in upstream impoundments, resulting in the potential accumulation of contaminants and reducing the ability of dams to serve their primary purpose of water storage. We utilized ground penetrating radar (GPR) surveys and digital elevation model (DEM) differencing to estimate the volume of sediment stored behind Ball Mountain Dam, a 50-year-old flood control facility constructed in Jamaica Vermont.
Collaborators: Frank Magilligan, W. Brian Dade, Carl Renshaw (Dartmouth College), Steve Arcone,
Dave Finnegan (US Army Corps of Engineers)

4. Quantifying Sedimentation Rates from Inlet Delta Stratigraphy
We performed a stratigraphic survey on the inlet delta of Beddington Lake, a mainstem pond on the Narraguagus River in coastal Maine. Traditional soil pits, sediment cores, and ground penetrating radar surveys were utilized. Beddington Lake underwent a water level transgression due to the installation of a dam on the lake in ~1850. When the dam was removed in 1951, a subsequent water level regression occurred. Deltaic stratigraphy revealed differences in sediment physical characteristics (grain size, bulk density, loss-on-ignition) between pre-dam, dam-influenced, and post-dam sedimentary packages. Sedimentation rates over each historic period were also quantified.
Collaborators: Noah Snyder (Boston College), Ilya Buynevich (Temple University),
Elizabeth Johnson (Boston College)