One Harvey “before and after” aerial photo showed a golf course under water, while surrounding homes were relatively high and dry. That low-lying course functioned just as land planners envisioned, storing floodwaters to protect valuable real estate above. While great in urban planning theory, it’s not a great reality for courses in floodplains, who deal with irregularly scheduled revenue losses, and continually increased maintenance and repair costs.
While no design could withstand hurricanes like Harvey and Irma, they raise the question of how design can mitigate flood damage? Here are tips to deal with flood damage.
- When projecting rounds, revenues and expenses, include typical lost play days over the long term. You may not have the rounds potential of nearby courses.
- Keep all as built plans on second floor, store off site, and have digital copies.
- Check your insurance policy. I have seen some courses better insured for dining room theft than loss of golf course use, which is sometimes limited to tree loss only.
Understand Regional Hydrology – Hire an engineer or look at a USGS quad map to understand your watershed and flood potential, if not known already. Each course has unique hydrology and related problems.
In terms of golf course design:
Greens, Tees and Fairways – Raise as far as practical, ideally consistently elevating, if practical:
- Greens to 12 – 18 inches above the recorded 100-year flood elevation so all USGA method layers are protected. If not practical, attain at least 25 or 50-year levels.
- Tees to 10, 25 or 50-year levels.
- Fairways to 2, 5, or 10-year flood levels, while leaving (or lowering) roughs, lakes, and less critical areas to act as detention reservoirs.
- Where it’s not possible to raise fairways, re-grade them with 3 – 6% minimum slopes to drain quickly.
- Design irrigation and drainage systems with discharge values to allow lowering of lakes to increase storage capacity before a known rain.
Cart Paths – Your paths are your main access routes, and higher paths gets you back out there sooner. Consider raising them as high as feasibly and aesthetically possible, being sure to take care of resulting drainage issues. This also reduces future minor drainage additions as silt builds up along grade level paths.
Drainage – Many golf course drainage systems are undersized, with small pipe and catch basins, which tend to clog easily. Consider:
- Larger drain pipes, which provide/allow:
- More capacity, (surprisingly so….an 8-inch pipe has 4X the capacity of a 4-inch pipe)
- Flatter grades to achieve “self-cleansing velocity (3 feet per second). A handy rule of thumb for estimating minimum pipe slope is “5/pipe diameter” (i.e., 5/4” = 1.25% minimum slope, 5/10” = 0.5%, 5/12” = 0.4%, 5/15” = 0.33%, etc.)
- Larger catch basins, whether flood prone or not, since catch basins (not pipe size) are usually the limiting factor in drainage capacity, even before clippings clog them up.
- Use engineering formulas to size pipe - Turf can die within 3 days when flooded in hot weather, so I design all pipes to drain a 100-flood within 3 days, where practical.
- Add 48-inch manholes every 300-500 feet on long drainage trunk lines, which are big enough to allow man and roto rooter down to clean the system when required.
Slopes and Channels – Bare ground erodes when water flows exceed 1.5 – 3.5 feet per second, depending on soil type. Well turfed swales resist erosion when flow is twice as fast, depending on grass type. Armoring your channel banks with erosion control netting, or using rip rap or gabion walls, on fast flowing banks can reduce flow damage. These can be ongoing projects.
Slow Flood Waters Down –When designing Indian Creek in Carrollton, Texas, architect Dick Phelps realized the raised greens and tees formed the nucleus of a continuous dyke. He filled gaps with mounds and ridges, forming a “sneaky” and aesthetically pleasing flood control berm to control flood waters under a 10-year storm.
I have created berms that force fast flowing water from directly entering the golf course, but allow it to “back in slowly” from the low point, to reduce erosion damage while maintaining flood storage capacity.
Speedlood Waters up – Sometimes, creek bends cause water to back up. Without touching the stream we have created straighter “short cut” channels just above the fast flow line that keep water flowing away from critical areas.
Irrigation System – When installing any new system:
- Elevate pump station and controllers on earth fill above flood levels.
- Put computer system on second floor of maintenance building
- Use 2-wire decoder system to minimize wires and controllers.
- Use 18-inch swing joints instead of 12-inch to make periodically raising sprinkler heads above new silt caused grades easier.