Caribbean District Science Plan SE Region August 23, 1999

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Caribbean District Overview Puerto Rico and the
U.S. Virgin Islands Matt Larsen, USGS Caribbean
District Chief
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St. Thomas
Culebra
Puerto Rico
St. John
U.S. Virgin Islands
Vieques
Mona
CARIBBEAN SEA
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30 KILOMETERS
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St. Croix
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30 MILES
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San Juan, Puerto Rico, 2001
Puertorican carnival costumes and masks
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Caribbean District program
Local cooperators PR Environmental Quality
Board PR Aqueduct and Sewer Authority PR Dept. of
Natural Environmental Resources PR Civil
Defense PR Dept. of Public Health PR
Environmental Quality Board PR Electric Power
Authority PR Infrastructure Authority VI Dept. of
Planning Natural Resources Municipal governments
District established in 1958 hydrologic data
collection and studies in PR and the USVI
current annual budget 6.3 million 40
employees
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Caribbean District home page
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USGS Rainfall data, Puerto Rico October 16, 2002
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Simplified geologic map of Puerto Rico
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Principal controls on the frequency and magnitude
of precipitation in the Caribbean basin
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Hydrologic cycle
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Caribbean islands are particularly vulnerable to
hydrologic extremes from hurricanes to drought
Peak flow, dam at Loíza reservoir, Hurricane
Hortense, September 1996
Hurricanes can deliver as much as 50 percent of
annual rainfall in 24 hours most of the runoff
is lost to the ocean
Satellite image of Hurricane Georges over Puerto
Rico, September 1998
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Historic North Atlantic hurricane tracks (Aug. 16
to Oct. 15, 1874-1944)
August 16 to 31
September 16 to 30
September 1 to 15
October 1 to 15
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Hurricane effects
Post-Hurricane Hugo, 1989 - fluvial sediment
plumes, north and west PR - defoliation, east PR
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Geography of Puerto Rico
Ponce
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Karst topography of the north coast
Annual precip 1,500 to 2,000 mm
Haystack hills
Caves
Sinkholes
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The south coastal plain of Puerto Rico lies
in a rain shadow MAP lt 1,000 mm Irrigated
agriculture, poultry, and cattle are the dominant
industry
Irrigation canal
water supply production well
Hilltop storage tank for water supply
Freshly plowed ñame (taro) field
Central mountains block moisture transport
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Eastern mountains Luquillo Experimental Forest
A 113 km² broad-leafed tropical evergreen
forest preserve in eastern Puerto Rico
administered by the U.S. Forest Service since
1917 previously was protected by Spanish crown
Site of the USGS WEBB project (Water, Energy,
and Biogeochemical Budgets) since 1991
LTER (Long-term Ecological Research) site since
1988
Quebrada Guabá, USGS streamflow station 50074950
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Integrated Surface-Water, Ground-Water, and
Water-Quality Networks Database management of
surface-water, ground-water, and water-quality
information
Data Collection
Data Management
Flow duration and flood frequency analysis
Real-time simulations of floods Ground-water
flow and solute transport simulations
Management Applications
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How are hydrologic data collected?
Local Terminals
pr.water.usgs.gov
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• 135 hydrologic data collection sites equipped
  with satellite telemetry
• 109 surface-water stations consisting of
• 91 Stream-flow stations
• 18 Reservoir elevation stations (lake stations)
• 121 rainfall stations
• 2 meteorological stations

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• 99 ground-water stations
• over 5,000 wells inventoried

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• 72 sampling stations
• 59 -- biological
• 60 -- chemical
• 7 -- pesticides
• 28 -- sediment

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List of constituents in standard sampling
protocol for QW stations.
 
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Surface-water, ground-water, and water-quality
network for the U.S. Virgin Islands

• 24 stations
• 5 ground-water stations (water level
  measurements)
• 6 partial ground-water stations
• 6 ground-water quality stations
• 4 surface-water stations
• 3 meteorological stations
• 0ver 1,000 wells inventoried

Surface-water station
Recording well
Water-quality well
Partial record well
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Hydrological problems Effects of land-cover
changes

• peak flow, baseflow, and water-quality
• quantity of potable water available at intakes
• high sedimentation rates in reservoirs
• minimum flows necessary for aquatic fauna and
  dilution of STP effluent

2001 Forest cover 30. Urban cover 18
Forest cover dominated pre-Columbian Puerto Rico
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History of land-cover changes 1825 to 1995
Larsen, M.C. and Santiago-Román, Abigail , 2001,
Mass wasting and sediment storage in a small
montane watershed an extreme case of
anthropogenic disturbance in the humid tropics in
Dorava, J. M., Palcsak, B.B., Fitzpatrick, F. and
Montgomery, D.eds., American Geophysical Union
Water Science Application Volume 4, Geomorphic
Processes and Riverine Habitat, p. 119-138.
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Ground water resource problems
Most important aquifers in Puerto Rico
and the U.S. Virgin Islands are vulnerable
because they are in coastal areas. The
shallow-coastal aquifer systems have been
negatively impacted by agricultural land
reclamation and malaria control projects.
Aquifer overdraft has caused saline-water
intrusion. Recharge of the south coastal
plain aquifer system in Puerto Rico is decreasing
due to the changes in irrigation practices
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Main concerns
Ecological Health of watersheds

• Sedimentation
• Eutrophication
• Hydraulic modifications
• dredging and channelization
• Oil and untreated sewer discharges
• Coral reef degradation impact on tourism and
  coastal erosion
• Sand and gravel mining within river channels

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Aquatic water quality is highly variable
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Natural hydrologic geomorphic processes we
inherited Frequent tropical disturbances
Dynamic, flashy rivers Landslide disturbance
(dominant control on river sediment loads, after
humans)
Landslides in the Luquillo mountains are the
source of more than half of the annual fluvial
sediment load (200 to 800 metric tonnes/km²/year)
Streams draining the Luquillo mountains are
flashy and are usually at baseflow high flows
rarely last more than a few hours because of
steep gradients and small contributing area
Larsen, M.C., and Torres Sanchez, A.J., 1998, The
Frequency and Distribution of Recent Landslides
in three MontaneTropical Regions of Puerto Rico
Geomorphology, v. 24, p. 309-331.
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Natural hydrologic geomorphic processes we
inherited
Debris avalanches caused by tropical disturbances
in 1970, 1989 (Hurricane Hugo), Luquillo
Mountains, Puerto Rico
from October 1970 Tropical depression
from H. Hugo, 1989
Abandoned two-lane highway (191)
Note defoliation and blowdown from Hurricane
Hugo Hurricanes are the dominant control of
forest ecology in the West Indies
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Rainfall intensity, mm per hour
Rainfall duration, hours
Larsen, M.C., and Simon, Andrew, 1993,
Rainfall-threshold conditions for landslides in a
humid-tropical system, Puerto Rico Geografiska
Annaler, v. 75A (1-2), p. 13-23.
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Natural hydrologic geomorphic processes we
inherited
Puerto Rico has no natural lakes potable water
storage is a major problem for the island
Lago Dos Bocas, south of Arecibo
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Hydrologic hazards
Flood map, Bayamon, PR
Landslide susceptibility map, Comerio, PR
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Hydrologic hazards

• Floods, droughts, and landslides
• Hurricanes 1.9 billion in damages, last decade
• Landslides--worst disaster in U.S. history
  Barrio Mameyes, Ponce, Puerto Rico with 100
  fatalities
• Droughts severely affect public water-supply
  sources gt6 months of rationing to gt1 million
  people in 1994-1995

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Water supply in Puerto Rico What is the problem?
high per capita consumption 534 liters/day in
1998 (consumption increased at 4.3 per year
between 1959 and 1998)
high wastage rates 40 of water produced is
lost (U.S. rate is 10)
high population growth rate 1.1 per year
between 1959 and 1998
high rates of reservoir storage loss 1.3 per
year at Lago Loíza
below average rainfall during the 1990s
Satellite image of Caribbean at night
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The drought of 1994-1995 was the worst in the
history of Puerto Rico rainfall deficit
anthropogenic factors
Water distribution point, Carolina, 1995
40 years of sedimentation had eliminated about
half of the storage capacity of the Loíza
reservoir by 1994
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Mean annual rainfall at the 12 longest-running
stations in PR
Y (-2.4X) 6451
Y (-2.4X) 6451
Mean, 1900-1929 1735 mm Mean, 20th century
1660 mm Mean, 1990s 1481 mm 1990s
mean/century mean 89 Decline 254 mm (15)
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Whats going on with our water?
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What happens to reservoirs in a drought?
Larsen, M.C., 2000, Analysis of 20th century
rainfall and streamflow to characterize drought
and water resources in Puerto Rico Physical
Geography, v. 21, p. 494-521.
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THANK YOU Find us on the web pr.water.usgs.gov
Matt Larsen USGS Caribbean District
Chief mclarsen_at_usgs.gov