The District currently maintains 90 Federal harbors and can focus significant experience to solve a wide range of complex coastal challenges. Our team of coastal engineers and scientists provide innovative solutions many coastal issues.
Complex Wave Modeling
State-of-the-art numerical models and 3-D physical models can be used in solving complex coastal problems.
The Physical Model shown below (Figure 1) was used to determine sediment flow patterns around a Coast Guard Station in Port Huron, MI. Results were used to help determine structural solutions to reduce accretion problems.
Figure 1 - Physical Model
CGWAVE (Figure 2) is a state-of-the-art wave agitation model used to describe wave climates in enclosed areas, such as harbors. It was utilized here to determine wave-focusing at Grand Haven Harbor to gain a better understanding of erosion within the harbor.
Figure 2 - CGWAVE Output
Harbor Circulation Modeling and Design
In-depth analyses using computer and physical modeling are used to improve and understand harbor interaction with waves and sediment flow within the the coastal region.
Recent studies at Saugatuck, MI, Michigan City, IN and St. Joseph, MI utilized a computer model called Hydrosed. This model is a 2-D hydrodynamic model comprised of three components:
Spectral Wave Transformation Model
Sediment Transport Model
All these modules comprise a state-of-the-art numerical model used to determine sediment transport pathways around harbor structures. Figure 3 shows sediment transport driven by a Northwestern storm at Saugatuck Harbor, MI. In-depth analyses using computer and physical modeling are used to improve and understand harbor interaction with waves and sediment flow within the the coastal region.
Figure 3 - Sediment Transport
Coastal Data Collection
Numerous data-sets are collected, ranging from survey data to satellite imagery to support decision making on coastal issues.
This imagery provides geographically rectified photography with exceptional resolution from orbiting satellites. This, along with geo-rectified aerial photography , is very useful in determining shoreline changes for large areas over various time periods. Figure 4 is a sample image of the St. Joseph, MI Water Treatment facility.
Figure 4 - Satellite Imagery
This source of data is used to determine sand thickness within the nearshore region. It is an invaluable data set when determining potential exposure of the underlying cohesive material. Figure 5 shows an example of the device used to collect the data
Figure 5 - Jet Probing
Bathymetric data is essential information when determining nearshore wave characteristics, such as refraction and shoaling. There are a number of various ways of obtaining this data. Figure 6 is SHOALS data along Michigan shoreline in Allegan County. It is high-resolution bathymetric data, akin to LIDAR data obtained on land (also available through the Corps). The Detroit District also collects conventional boat surveys.
Figure 6 - Bathymetric Data
Recession Rate Analyses
Accurate shoreline change rates covering large stretches of shoreline are important in establishing setback distances for environmentally safe construction.
Utilizing the FEPS (Flooding and Erosion Protection System), bluff recession over defined temporal periods can be calculated to determine proper location for structures. Figure 7 shows a stretch of shorleline in Allegan County Michigan. By analyzing wave energy during high water (wet) and low water (dry), we have been able to illustrate the diffent rates of recession associated with each. The figure shows the potential locations of the bluff tops 50-years into the future.
Figure 7 - Flood and Erosion Protection System
Beneficial Reuse of Dredged Material and Beach Nourishment
Utilizing a "system-based approach", dredged sediment is managed to gain maximum benefit from limited sand supplies. Placement of beach suitable material within the nearshore region helps in maintaining the health of beaches along our Great Lake shorelines. Figure 8 illustrates a typical method used in placing sediment dredged from a harbor along the shoreline. A sand/water slurry is hydraulically pumped from the lake bottom to the beach through a pipe. Once the material is allowed to dry, bulldozer are typically used to manicure the placed sediment so that the beach is usable (Figure 9). Placement of dredged sediment in the Great Lakes restablishes littoral transport around structures to help maintaing the health of the as opposed to engineering beaches.
Figure 8 - Typical Placement of Dredged Sediment
Figure 9 - Spreading Placed Sediment
Sediment Budget Analysis System (SBAS) is useful for determining sediment quantities within the nearshore system. Utilizing other tools, such as Hydrosed, eCoastal, and COSMOS, SBAS can provide invaluable data on beach placement of dredged sediment. Figure 10 show how SBAS is used to account for sediment within a sediment budget.
Figure 10 - Sediment Budget Analysis System (SBAS)