WHEN TO DREDGE?

1
WHEN TO DREDGE?
2
RECOMMENDED

• WHEN THE THROAT OF THE PASS FALLS BELOW 200
  SQUARE FEET IN CROSS-SECTION

3
PROBLEMS

• DOES NOT TAKE INTO CONSIDERATION HEALTH (NEEDS)
  OF THE MANGROVES
• IS A SNAPSHOT ONE EVENT
• WHO DECIDES WHEN TO TAKE SNAPSHOT BASED ON WHAT
  CRITERIA?
• EFFECT OF LUNAR CYCLE
• WIND DIRECTION SPEED
• VOLUME OF WATER FLOWING THROUGH THE THROAT
• SEASONAL WEATHER PATTERNS

4
PROBLEMS(CONTINUED)

• DAMAGES CAUSED BY DREDGING
• TO SEA-GRASSES
• TO BENTHIC COMMUNITIES
• TO EBB-SHOAL WHEN BRINGING IN THE DREDGE
  EQUIPMENT
• DISTURBING EXISTING SEA-LIFE
• BLOCKING ACCESS TO GULF FOR SEAGATE RESIDENTS,
  WHILE DREDGE ON LOCATION

5
PROBLEMS(CONTINUED)

• RECOMMENDATION DOES NOT MEASURE THE EFFECT OF
• RAINFALL IN THE MANGROVES
• WATER ENTERING FROM NEIGHBORING PROPERTIES
• FRESH WATER UP-WELLING THROUGH-OUT THE SYSTEM
• THE ADDITIONAL BENEFIT THESE CREATE IN THE
  FLUSHING OF THE THROAT
• DOES NOT ADDRESS SEASONAL DIFFERENCES IN
  RAINFALL/DROUGHT

6
SUGGESTION

• WE NEED TO MEASURE THE EFFECTIVENESS OF THE
  THROAT
• THIS CAN EASILY BE ACCOMPLISHED
• IT HAS BEEN DONE SINCE 1998
• MEASURE THE QUANTITY OF WATER ENTERING THE BAYS
• MEASURE THE EFFECT FLOOD AND EBB TIDES HAVE ON
  THE BAYS
• MEASURE HOW LONG WATER REMAINS
• THIS CAN BE DONE ON A DAILY BASIS, NOT ON A
  SNAPSHOT BASIS

7
CONCLUSION

• DREDGING SHOULD ONLY BE CONSIDERED IN CONJUNCTION
  WITH THE HEALTH OF THE MANGROVES
• USE TIDAL FLOW DATA TO MEASURE THE EFFECTIVENESS
  OF THE THROAT.