Keywords
Two-Stage Ditch, LiDAR
Presentation Type
Event
Research Abstract
Drainage ditches are a major pathway for sediment, nutrients, and pesticides to enter stream systems, which threaten environmental and human health. Unlike trapezoidal ditches, two-stage ditches have a vegetated bench that acts as a floodplain, which helps to prevent erosion and to increase the processing of nutrients to improve water quality. Converting a trapezoidal ditch to a two-stage ditch is expensive, due to the large volumes of soil that need to be excavated. Since ditch geometries vary significantly and surveying each potential site by hand would be time consuming and expensive, a tool based upon online Light Detection and Ranging (LiDAR) data would be useful to estimate the volume.
The excavation volume for two ditches was calculated using two methods: the LiDAR digital elevation model, gridded to 3 m resolution, and a ground survey using an RTK GPS unit. ArcGIS was used to create profiles of the trapezoidal streams. Hypothetical two-stage cross-sections were created by calculating the bankfull depth, based on the drainage area, and the width, using a three to one bench slope. OriginPro was used to find the difference between the area under the two-stage cross-section and the original trapezoidal cross-section.
The estimated volume differed between the two methods. While the LiDAR based volume of one ditch was within 16.9% of the RTK GPS based volume, the other ditch’s volumes varied by 22.5%. This suggests that using the LiDAR DEM may not provide sufficient accuracy for this estimate, although it could provide a rough cost estimate without time-consuming surveys.
Recommended Citation
Kirsten E. Paff, Jane Frankenberger, and Naime Celik,
"Estimation of Two-Stage Ditch Excavation Volume Using LiDAR Data Full Paper"
().
The Summer Undergraduate Research Fellowship (SURF) Symposium.
Paper 4.
https://docs.lib.purdue.edu/surf/2013/presentations/4
Estimation of Two-Stage Ditch Excavation Volume Using LiDAR Data Full Paper
Drainage ditches are a major pathway for sediment, nutrients, and pesticides to enter stream systems, which threaten environmental and human health. Unlike trapezoidal ditches, two-stage ditches have a vegetated bench that acts as a floodplain, which helps to prevent erosion and to increase the processing of nutrients to improve water quality. Converting a trapezoidal ditch to a two-stage ditch is expensive, due to the large volumes of soil that need to be excavated. Since ditch geometries vary significantly and surveying each potential site by hand would be time consuming and expensive, a tool based upon online Light Detection and Ranging (LiDAR) data would be useful to estimate the volume.
The excavation volume for two ditches was calculated using two methods: the LiDAR digital elevation model, gridded to 3 m resolution, and a ground survey using an RTK GPS unit. ArcGIS was used to create profiles of the trapezoidal streams. Hypothetical two-stage cross-sections were created by calculating the bankfull depth, based on the drainage area, and the width, using a three to one bench slope. OriginPro was used to find the difference between the area under the two-stage cross-section and the original trapezoidal cross-section.
The estimated volume differed between the two methods. While the LiDAR based volume of one ditch was within 16.9% of the RTK GPS based volume, the other ditch’s volumes varied by 22.5%. This suggests that using the LiDAR DEM may not provide sufficient accuracy for this estimate, although it could provide a rough cost estimate without time-consuming surveys.