Water Management Under Severe Storm Conditions in Central and South Florida

Transcription

1 Water Management Under Severe Storm Conditions in Central and South Florida Chandra S. S. Pathak, Ph.D., P.E. Severe Storm Prediction and Global Climate Impact in the Gulf Coast Conference October 29 to 31, 2008

2 The South Florida Water Management District Covers 18,000 square miles Population more than 7 million FY 2008 Budget $1.3 Billion Oversees water resources in the southern half of the state Oldest and largest of Florida s s five water management districts Established by the legislature

3 The South Florida Water Management District Who we are and what we do: The SFWMD s mission is to manage and protect water resources of the region by balancing and improving water quality, flood control, natural systems and water supply. A key initiative is cleanup and restoration of the Everglades.

4 Topography

5 Topographic and Hydraulic Gradient 60 Lake Tohopekaliga 50 Lake Kissimmee Water surface elevation (ft NGVD) Lake Okeechobee EAA WCA 1 WCA 2 WCA 3 STAs ENP 0 FL Bay Distance in miles (Lake Tohopekaliga to Florida Bay)

6 The Upper Kissimmee Chain of Lakes form the headwaters of the Kissimmee- Okeechobee- Everglades watershed

7 Water Resource Modifications Historic Flow Current Flow

8 History Settlement in south Florida increased in the late 1800 s Navigation Improvements Everglades Drainage District Initial drainage works improved development opportunities Severe floods & droughts persisted

9 Water Resources Purpose Flood Control Water Supply Agriculture Urban Everglades National Park Saltwater Intrusion Navigation Protection of fish and wildlife

10 Upper Kissimmee Chain of Lakes Approximate Primary System Water Level Management Ranges (values in feet, NGVD) Note: Map ranges consider seasonal operating variation & generally represent a system of canals &/or storage areas. Map values are primarily intended to show the relative spatial variability of operating stages. Lake Istokpoga Indian Prairie Canals North Basin South Basin Kissimmee River Lake Okeechobee UEC Canals St. Lucie River 14.5 Caloosahatchee River 3.0 EAA WCA-3A WCA-2A WCA PB Co. Canals Brow Co. Can 3-6 SDCS Canals 2-6 Dade Co. Coastal Canals 1-2

11 Central and South Florida Project Central and Southern Florida Project for Flood Control and Other Purposes Initially authorized in 1948 Constructed between 1950 s and 1970 s Operated in accordance with USACE criteria USACE SFWMD

12 Major C&SF Project Components River Channelization Herbert Hoover Dike Water Conservation Areas Protective Levees Everglades Agricultural Area Lower East Coast Drainage Network Salinity Structures

13 Water Management System Components ~1,900 miles of canals and levees 160 major drainage basins 550+ major structures 200+ remotely operated 300+ manually operated or fixed structures About 50 pump stations Almost ½ with remote operation capability

14 Hydrologic Monitoring Network Rainfall Weather Stations 279 active rain gauges NEXRAD Radar rainfall 41 full and partial stations Surface Water Level 1195 active gauges Surface Water Flow 420 active flow sites Groundwater 975 active wells

15 Water Management The water management system is operated by SFWMD, USACE and in cooperation between them USACE regulates Lake Okeechobee water level in consultation with the SFWMD USACE operates inflow and outflow structures on the Caloosahatchee and St. Lucie Rivers USACE operates outflows from WCA 1, WCA 2 and WCA 3 SFWMD operates the rest of the system

16 Water Management Decision Making Environmental Advisory Team Weekly Meeting District Operation of Water Control Structures Continuous monitoring and decision making using water control manual Automated and remote controlled sites Automated sites Manually operated sites

17 Drainage Responsibilities

18 Primary System Operations - Drainage & Flood Control - Water Supply

19 Typical Coastal Canal Operations: Runoff conveyed away from developed areas mitigate flood impacts Structure operations coordinated from District headquarters Most critical structures remotely automated Manual operations coordinated with local field stations Drainage

20 Canal / Groundwater Interaction Normal Dry Season Operations Canals Canals serve serve two two primary purposes Flood Flood Control Water Water Supply Supply Canal stages held held high high to to facilitate groundwater recharge and and assist supplemental irrigation Groundwater Low Low groundwater levels levels due due to to low, low, dry dry season season rainfall rainfall

21 Canal / Groundwater Interaction Normal Wet Season Operations Canal stages low low to to facilitate surface drainage of of urban & ag ag lands Groundwater Long-term low low canal canal stages stages depress regional groundwater levels levels

22 Canal / Groundwater Interaction Pre-Storm Drawdown Operations Canal Canal stages stages lowered an an additional ~1 ~1 foot foot to to increase surface drainage of of urban urban & ag ag lands lands prior prior forecasts storms storms Groundwater Short-term Short-term lowering lowering of of canal canal stages stages does does not not significantly significantly decrease decrease regional regional groundwater groundwater levels levels

23 Upper Kissimmee Chain of Lakes Operations 6 major lake pools Kissimmee, Hatchineha & Cypress Toho East Toho Hart & Mary Jane Myrtle, etc. Alligator, etc. 7 major water control structures Lake Toho S-61 S-61 Lake Hatchineha S-59 S-59 S-62 S-62 L. Hart / Mary Jane East Lake Toho L. Gentry Lake Cypress Lake Kissimmee S-60 S-60 S-58 S-58 L. Alligator S-60 S-60 S-63 S-63 S-63A S-63A S-65 S-65

24 Basic Lake Operations. Regulation Schedules Conceptual Profile

25 What is a Regulation Schedule? Tool for managing/regulating water levels in a reservoir/lake Triggers regulatory discharges (aka flood control discharges) Does not trigger water supply deliveries Designed to balance multiple & competing objectives

26 Regulation Schedules Represents seasonal & monthly storage limits Considers varying & often conflicting purposes Flood Control: Designed for no damages up to 30% SPF (~1 in 10 yr.) Water Supply: Runoff in wet season is stored for use in dry season 1 year Typical Annual Schedule

27 Flood Control Ops: Discharge Normal Ops: No Discharge

28 Winter Water Supply Pool Stage Pre-Hurricane Season Low Stage Transition to to Low Stage Transition to to Peak of of the Hurricane Season Summer Pool Stage

29 Lake Okeechobee Lake Okeechobee covers over 730 square miles, with a contributing basin of over 5,000 square miles Water levels driven largely by climatic conditions

30 Herbert Hoover Levee Issues The levee protects communities surrounding the lake from storm surge flooding High stages place tremendous pressure on the levee which could effect stability Lake Okeechobee Hydrostatic Pressure Levee Schematic Herbert Hoover Levee Typical Seepage Site Underlying Limestone

31 Herbert Hoover Dike (U.S. Army Corps of Engineers)

32 Lake Okeechobee Major Water Control Structures Lake Okeechobee S-77 S-308 S-352 S-3 & S-354 S-2 & S-351

33 Typical Lake Okeechobee & Estuary Flows During Wet Periods Lake Inflows S80 Discharge to St. Lucie Estuary C-43 Basin Runoff Lake Release at S-308 C-44 Basin Runoff S79 Discharge to Caloosahatchee Estuary Lake Release at S-77 EAA Runoff Lake Release through EAA to WCAs (via STAs) &/or to tide

34 Lake Okeechobee Design Discharge Capacities Inflows to the lake frequently exceed total outflow capacity Outflow capacity to the St. Lucie & Caloosahatchee far exceeds outflow capacity to the Water Conservation Areas East & West 86% Design Cap (cfs) Lake Okeechobee Structure Capacity INFLOW Lake Okeechobee Outflow Capacity South 14% OUTFLOW

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37 C&SF Project Strengths & Weaknesses Provides significant benefits to developed areas Flood control Water supply Unintended ecological impacts associated with C&SF construction and operation

38 The 2005 Hurricane Season in South Florida Hurricane Dennis (July 8-10, 2005) Hurricane Katrina (August 24-27, 2005) Hurricane Rita (September 19-21, 2005) Hurricane Wilma (October 22-25, 2005)

39 Hurricane Wilma (October 22-25, 2005)

40 Hurricane Wilma October 2005

41 Rainfall from Hurricane Wilma Rainfall from Hurricane Wilma Upper Kissimmee E Caloosahatchee Lower Kissimmee Southwest Coast Lake Okeechobee West EAA Martin-St. Lucie Big Cypress Basin East EAA Broward WCA-3 WCA-1&2 Rainfall (inces) Palm Beach Miami-Dade ENP Rainfall Areas

42 10/24/2005 0:00 10/24/2005 1:00 10/24/2005 2:00 10/24/ :00 10/24/2005 3:00 10/24/2005 4:00 10/24/2005 5:00 10/24/2005 6:00 10/24/2005 7:00 10/24/2005 8:00 10/24/2005 9:00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/24/ :00 10/25/2005 0: Wind Speed at Belle Glade Weather Station 15-minute average wind speed 15-minute maximum wind gust Hour of the day (October 24, 2005) Wind speed (mph)

43 S131 S4 S133 10/24 11:00 AM 105 mph NE ~25 mph S135 S352 10/24 9:00 AM 110 mph NE ~25 mph

44 Lake Okeechobee Water Level Fluctuation during Hurricane Wilma S-191 at the North S2 at the South Time of day (October 24, 2005) Water level (ft NGVD) 0:06 1:06 21:20 2:06 3:06 4:07 5:07 6:07 7:07 8:07 9:07 10:07 11:07 12:07 13:07 14:07 15:07 16:07 17:07 18:07 19:07 20:07 21:22 22:22 23:22 0:00 0:40 1:20 2:05 2:55 3:40 4:20 5:00 5:40 6:20 7:01 7:42 8:22 9:02 12:14 13:24 14:15 14:55 15:35 16:15 17:05 17:45 18:25 19:20 20:00 20:40 22:00 22:40 23:20 maximum recorder reading exceeded Water level (ft NGVD) Time of day (October 24, 2005)

45 Damage to Herbert Hoover Levee at Lake Okeechobee

46 Vegetation and Water Quality Impacts

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48 South Florida Water Resource Management Challenges Florida s climate is one of extremes System stressed by population & land use BALANCE Multiple water resource objectives Objectives often conflict

49 Questions?

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