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Coastal Engineering in Guyana
Amar Nayegandhi, Associate Vice President, Dewberry
Dewberry’s International Experience
• Through Dewberry International, Inc.
• Working with reliable sources of funding like the
World Bank, IDB
• Partnered with several firms on many international
pursuits
• International market (especially in developing
countries) has a lot of potential:
• Technology
• Expertise
• Experience
• Currently exploring other international markets
LiDAR, Imagery, Geodesy, and
Engineering Modeling QA/QC and
Review – Guyana Conservancy
Adaptation Program
Guyana
• Guyana officially the Cooperative Republic of
Guyana, is a sovereign state
on the northern coast of
South America.
• It is a Caribbean country but
not an island (part of
CARICOM)
Demographics
44% Indo-Guyanese
31% Afro-Guyanese
Population: 800,000
Source: Wikipedia
Guyana CAP Project History
• Narrow and fertile marshy, low-lying coastal
plain along the Atlantic coast is where most of
the population lives.
• The East Demerara Water Conservancy
(EDWC) and east coast drainage and
irrigation systems provide water storage and
flood control mechanisms for Guyana’s most
populous region, including the capital city of
Georgetown.
• In 2005, extreme rainfall caused devastating
flooding along these coastal lowlands, with
many areas remaining inundated for up to
three weeks.
• In 2008, World Bank sponsored the
Conservancy Adaptation Project (CAP)
• Funded by: Global Environment Facility (GEF)
Special Climate Change Fund (SCCF) grant
of US$ 3.8 million.
•
Published by Isabella Bovolo for the World Bank
Dates: January 2008 to August 2013.
CAP Objectives
• To strengthen understanding of the EDWC and the
coastal drainage systems through the development
of a hydraulic engineering foundation critical for flood
control management
• To identify strategic interventions for follow on
investments to reduce flood risk
• To implement selected infrastructure investments
aimed at increasing the drainage relief capacity of
the EDWC
• To strengthen institutional capacity to manage water
levels in the EDWC
Guyana CAP LiDAR and Imagery
survey
• Approximately 1,100 Square Kilometers
• 1,166 Tiles (1Km X 1Km)
• LiDAR data acquired in April 2011
• Hydro Flattened, bare earth model- 1m DEM
• Ortho Rectified RGB imagery
• Ground-based bathymetry surveys were also
conducted in the region
7
LiDAR data
LiDAR data
Geodesy issues
• Guyana has no GEOID model in
place
• Georgetown vertical datum is
offset by 15.505 m from EGM96.
• One survey monument on the
wall of a lighthouse is the gold
standard for the vertical datum.
Hydrologic and Hydraulic Modeling
• Computer models of the EDWC system and east
coast drainage areas were set up to help
understand how the hydrological system varies
under extreme weather scenarios and for testing
the impact of various proposed interventions.
Model Results
• Results of the models indicated that in 2005, even a
50-year rainfall event would have meant that water
levels throughout most of the conservancy would
have been above the safe operating level of the
dam.
• New Hope-Dochfur canal being built will reduce
water levels and improve drainage from the
conservancy for an extreme 10,000 year rainfall
event.
• Increasing discharge capacity to Demerara river at
the Land of Canaan (shallowest location in the
conservancy) will help lower water levels
significantly.
Dewberry’s role in CAP Project
• Dewberry assisted the Government of Guyana in the negotiations of the
engineering services contract for the pre-investment study for engineering
design of works with respect to the geodesy and mapping task.
• Also assisted the GoG in reviewing contractor approach and technology at
the start of the mapping and surveying component and provided expert
assistance in reviewing contractor QA/QC procedures, equipment and work
plan.
• Provided expert review and QA/QC observations for the GoG to assure the
data collection and analysis were consistent with the contract requirements.
This process reviewed procedures at key performance milestones and a
report was derived from these findings.
• LiDAR and orthophotography data were extensively reviewed (including
accuracy verification).
• Dewberry also reviewed several model runs that were conducted for the
CAP program. These included a rainfall-runoff model, 3 hydrodynamic
(unsteady state) models (both 1-d and pseudo 2-D models), a water supply
model, and climate change analysis on sea level and climate variability.
Dewberry provided several recommendations during the entire modeling
process that were incorporated by the contractor to better estimate the
parameters that were used in the models.
H&H Model review and comparisons
“A more detailed assessment of
the Land Of Canaan Gate
operation using an unsteady
state HEC-RAS with the gate
modeled as a structure ( with
gate closing and opening
times based on Land of
Canaan Upstream and
Downstream Water Levels)
resulted in discharges
inconsistent with the HYDRO1D modeling for this
structure.”
Institution Strengthening
• Dewberry was tasked
in March 2014 to
conduct training in
LiDAR products and
services.
• Tasked directly by the
world bank.
• How-to videos were
created
Lessons Learned
• Building trust is #1 priority
• Engage with the locals
• Learn a little about their
culture prior to visit and
ask lots of questions
• Build relationships
• Be sensitive
Thank you!
Questions?
Amar Nayegandhi
Associate Vice President
Dewberry
[email protected]
Ph: +1 813 421 8642
Mobile: +1 727 967 5005