New study highlights impact of current and historic land use on stream incision in Maryland Piedmont headwaters
A new method was developed to remotely identify small, eroding streams and measure change over time.
Issue
Urban or agricultural land use can result in stream incision, a condition where streams have steep, exposed banks that often erode and contribute excess sediment to downstream waterways. Knowledge of the spatial extent of incised streams is helpful for prioritization of water resource management objectives. The increasing availability of more detailed landscape models derived from light detection and ranging (lidar) has expanded our ability to remotely detect the shape of small streams, which have traditionally been under-represented by existing methods.
USGS study
This study describes a new method to locate eroding streams using landscape openness, which characterizes how open or enclosed a specific area is relative to the surrounding landscape.
For this study, the channel bottom was used as the specific area and the adjacent stream bank was used as the surrounding landscape. This new application of landscape openness identifies incised streams as being more enclosed than non-incised streams and was then used to monitor changes in the relative degree of enclosure (i.e. incision) in an area experiencing rapid urban development. We were able to assess changes in stream incision in two urbanizing watersheds using this method and lidar data available for the study area from before and after development. We also included a nearby forested watershed for comparison that underwent little land use change during the study period from 2002 – 2018, but was previously used for agriculture and then reforested in the 1970s.
Primary Findings
- While the degree and pattern of incision varied across the stream network in all three watersheds, results showed increasing incision over time, suggesting extreme weather events may have influenced the degree of erosion as much as recent land use change (figures 1 and 2).
- One urbanizing watershed experienced moderate incision while the other experienced more severe incision, despite a similar increase in development in both watersheds.
- A variety of factors such as differences in the level of incision prior to the start of urbanization, timing of construction, and differences in stormwater structures used in the two watersheds may all have contributed to differences in stream incision patterns.
Management Implications
- This new approach can be especially useful for rapid screening of stream conditions to help identify potentially eroding streams or to help explain water quality and aquatic habitat conditions.
- Areas of each watershed were already severely incised in 2002, highlighting the impacts of prior agricultural land use on current stream conditions in areas that have since been urbanized or reforested.
- This study adds to a growing list of applications using lidar-derived elevation data to monitor streams and landforms, and highlights the value of repeated collections to quantify change over time.
Publication Details
Metes, M.J., Miller, A.J., Baker, M.E., Hopkins, K.G., & Jones, D.K. (2024). Remotely mapping gullying and incision in Maryland Piedmont headwater streams using repeat airborne lidar, Geomorphology, Volume 455. https://doi.org/10.1016/j.geomorph.2024.109205
Associated data
- Metes, M.J., 2024, Channel incision characteristics in Clarksburg, MD: U.S. Geological Survey data release, https://doi.org/10.5066/P94M3MJC.
- Metes, M.J. and Jones, D.K., 2021, Lidar-derived digital elevation models in Clarksburg, MD representing the years 2002, 2008, 2013, and 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9YQFR17.
A new method was developed to remotely identify small, eroding streams and measure change over time.
Issue
Urban or agricultural land use can result in stream incision, a condition where streams have steep, exposed banks that often erode and contribute excess sediment to downstream waterways. Knowledge of the spatial extent of incised streams is helpful for prioritization of water resource management objectives. The increasing availability of more detailed landscape models derived from light detection and ranging (lidar) has expanded our ability to remotely detect the shape of small streams, which have traditionally been under-represented by existing methods.
USGS study
This study describes a new method to locate eroding streams using landscape openness, which characterizes how open or enclosed a specific area is relative to the surrounding landscape.
For this study, the channel bottom was used as the specific area and the adjacent stream bank was used as the surrounding landscape. This new application of landscape openness identifies incised streams as being more enclosed than non-incised streams and was then used to monitor changes in the relative degree of enclosure (i.e. incision) in an area experiencing rapid urban development. We were able to assess changes in stream incision in two urbanizing watersheds using this method and lidar data available for the study area from before and after development. We also included a nearby forested watershed for comparison that underwent little land use change during the study period from 2002 – 2018, but was previously used for agriculture and then reforested in the 1970s.
Primary Findings
- While the degree and pattern of incision varied across the stream network in all three watersheds, results showed increasing incision over time, suggesting extreme weather events may have influenced the degree of erosion as much as recent land use change (figures 1 and 2).
- One urbanizing watershed experienced moderate incision while the other experienced more severe incision, despite a similar increase in development in both watersheds.
- A variety of factors such as differences in the level of incision prior to the start of urbanization, timing of construction, and differences in stormwater structures used in the two watersheds may all have contributed to differences in stream incision patterns.
Management Implications
- This new approach can be especially useful for rapid screening of stream conditions to help identify potentially eroding streams or to help explain water quality and aquatic habitat conditions.
- Areas of each watershed were already severely incised in 2002, highlighting the impacts of prior agricultural land use on current stream conditions in areas that have since been urbanized or reforested.
- This study adds to a growing list of applications using lidar-derived elevation data to monitor streams and landforms, and highlights the value of repeated collections to quantify change over time.
Publication Details
Metes, M.J., Miller, A.J., Baker, M.E., Hopkins, K.G., & Jones, D.K. (2024). Remotely mapping gullying and incision in Maryland Piedmont headwater streams using repeat airborne lidar, Geomorphology, Volume 455. https://doi.org/10.1016/j.geomorph.2024.109205
Associated data
- Metes, M.J., 2024, Channel incision characteristics in Clarksburg, MD: U.S. Geological Survey data release, https://doi.org/10.5066/P94M3MJC.
- Metes, M.J. and Jones, D.K., 2021, Lidar-derived digital elevation models in Clarksburg, MD representing the years 2002, 2008, 2013, and 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9YQFR17.