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PROJECT EXPERIENCE
Tropical Storm Allison Recovery Project (TSARP) for Harris County, Texas - In the early
stages of this project, Chen-hua worked on the hydrologic modeling of the ‘Red’ region that
includes White Oak Bayou, Cypress Creek, Willow Creek, and Spring Creek watersheds. GIS
ArcView and Hec-GeoHMS were used for sub-basin delineation and to create the HEC-HMS
model input file frameworks. Later, Chen-hua was in charge of QA/QC and reviews for the
hydrology and hydraulic submittals from the project contractors. The submittals included HECHMS and HEC-RAS models as well as the corresponding LiDAR and GIS data for each of the
watersheds. Meanwhile, he also implemented the Rummel Creek Hydraulic Model Revision
using HEC-GeoRAS and LiDAR information. The Rummel Creek project was one of the
Additional Stream Modeling tasks connected to TSARP. Chen-hua served as the main force in
accomplishing these TSARP tasks described above.
Brazoria County Master Drainage Plan, Brazoria County, Texas - This project called for the
revision of complete hydrologic and hydraulic models for major watersheds including Chocolate
Bayou, Mustang Bayou, and the Brazos River, etc., the identification of existing flooding
problems, and the development of recommendations regarding cost-effective and long-term
solutions. As a project engineer, Chen-hua was in charge of data collection, modeling, and
analysis. He provided recommendations to detected problems, and composed the final report.
Regional Watershed Modeling System for The San Antonio River Basin, Martinez Creek
and Calaveras Creek Watersheds, Bexar County, Texas - This project involved the
development of hydrologic modeling for the eastern portion of Bexar County and vicinity for an
area of approximately 150 square miles. GIS ArcMap with the PrePro-2002 extension was used
to delineate the sub-basin boundaries based on the Digital Elevation Model (DEM) data
obtained from the USGS National Elevation Dataset (NED), and to generate the HEC-HMS
model input data framework. This model includes seven and six flood control dams in the
Martinez and Calaveras Creek watersheds, respectively. The as-built plans for the dams were
used to create the rating curves for the reservoirs. Chen-hua served as the primary engineer for
this project and prepared the data and parameters for the modeling.
Storm Water Drainage Plan for Proposed Commercial, Multi-Family, and Single-Family
Residential Developments in the Upper Clodine Ditch Watershed, Fort Bend County,
Texas - This project consisted of an analysis to a master drainage plan for a number of future
commercial and multi-family residential developments located within the upper Clodine Ditch
(Long Point Slough) watershed. In order to limit the outflow discharge rates to meet the LID
No.12’s criteria, two regional basins near the LID No.12/MUD No.50 outlet and an expansion to
the FM1093 detention basin were proposed. Via interactions between the HEC-HMS model and
the corresponding unsteady flow HEC-RAS model, it was proved that the proposed regional
basins will perform equivalently to multiple on-site detentions provided in each of the future
developments, and would limit the downstream peak discharge rates of Clodine Ditch to the
existing levels. Chen-hua was in charge of the dynamic analysis for this project.
Drainage Analysis for Proposed Alvin Apartment Developments, Alvin, Brazoria County,
Texas - The project is associated with an analysis of storm water drainage requirements for a
proposed 30-acre multi-family development and a 132-acre single-family residential and
commercial development within the Brazoria County Drainage District No. 3 (DD3) drainage
area. To establish a drainage system for the proposed developments and an off-site drainage
area, Chen-hua designed two connected regional basins along with an improved drainage ditch.
The hydrologic and hydraulic analyses results indicate that, with regional basins and improved
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ditch in place, the proposed developments have no impact to the existing DD3 drainage ditch
and Mustang Bayou flood hazard conditions
Use of Sand Pit Adjacent to South Mayde Creek as Regional Detention for Proposed
Developments, Harris County, Texas - The purpose of the analysis is to determine and
document how the sand pit might be used to provide regional detention for a number of
proposed developments and on-site basin removal sites in the vicinity of the sand pit. Most of
these tracts are proposed to drain to the pertinent outfall channels that lead to the sand pit basin
for detention before discharging to South Mayde Creek, and a few drain directly to South Mayde
Creek. Chen-hua developed unsteady flow HEC-RAS models for the system to evaluate the
feasibility of the regional detention plan. The result indicates that, as a regional basin, the
improved sand pit mitigates the potential impacts caused by the proposed developments, no onsite detention is required for each of the service areas, and no adverse impacts on existing
flooding conditions along the South Mayde Creek (U101-00-00) or Ditch U101-05-00 are
anticipated for storm events up to and including the 1% (100-year) event.
Hydrologic and Hydraulic Impact Analysis for Cypress-Rosehill Road Improvements,
Harris County, Texas - Chen-hua analyzed and evaluated the local impact, watershed impact,
and bridge hydraulic impact caused by the road project. A detention basin was proposed near
the northwest corner of the Little Cypress Creek and Cypress-Rosehill Road to mitigate such
that the peak discharge rates to the creek can be attenuated to the existing condition level. The
proposed multi-opening crossing structure was elevated and RCB culverts were proposed
immediately north of Little Cypress Creek maintain the existing condition 100-year flood level.
Genoa-Red Bluff Road and Bridge Improvement Impact Analysis, Harris County, Texas Chen-hua revised the 100-year peak flow rates along Armand Bayou by considering the as-built
and approved regional detention basins within the upstream watershed and then developed the
proposed conditions HEC-HMS and HEC-RAS models, which included proposed road profile,
bridge geometry, and mitigation basins, to show that the proposed roadway will avoid flooding
during a 100-year storm event.
TxDOT Grand Parkway Hydraulic Modeling for Proposed Brazos River and Oyster Creek
Crossing Bridges, Fort Bend County, Texas - As the Brazos River and Oyster Creek
watersheds used to encounter flooding problems during flood season, for this project, Chen-hua
proposed three alternatives for the crossing bridges over Brazos River and Oyster Creek, which
have low chord elevations above the 100-year flood levels, and encoded the structure
geometries in the HEC-2 model for hydraulic analysis. Pros and cons were analyzed for each of
the alternatives.
TxDOT US 59 Culvert and Drainage Analysis, Harris County, Texas - The TxDOT design
tools “Culvert” software and MicroStation were used to develop the highway drainage analysis
for US 59 from McClesky Road to Fostoria Lane. The culvert styles and dimensions were
proposed for each roadway segment based on the hydrology and hydraulic analysis results.
TxDOT FM 2100 Drainage Design and Bridge Analysis, Harris County, Texas – Three tasks
were included in this project. Chen-hua designed the roadside ditch system and outfall channel
to drain the northern segment westward to East Fork San Jacinto River. He also proposed and
modeled the southern segment road side ditches in HEC-RAS models to prove that the 100year flows can be conveyed by the proposed ditches without flooding. In addition, Chen-hua
showed based on the HEC-RAS model outputs that the proposed Luce Bayou crossing bridge
has no adverse impact to the San Jacinto River flood hazard conditions.
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Use of XP-SWMM to Assess Detention and Trunk Storm System for the Parkway Lakes
Subdivision, Fort Bend County, Texas - The XP-SWMM computer software has been used
by Chen-hua to analyze the proposed detention and trunk storm system on the “Shops at
Parkway Lakes” site. The SWMM model developed for this analysis consists of three on-site
detention basins linked by culverts and a long trunk storm sewer that follows a roughly semicircular path as connections to the detention facilities. Sites of major stores were assumed to
drain directly to the detention facilities and the pad sites will drain to the trunk storm system.
Runoff hydrographs are input to the SWMM model at the detention basins and at a number of
approximate manhole locations at which pad sites are assumed to tie into the trunk storm sewer
system. The results of the XP-SWMM analysis indicate that 72-inch reinforced concrete pipes
are required for the trunk storm sewer system. The pipe system provides an additional 2.1
acre-feet of detention storage, bringing the total available detention storage to 44.8 acre-feet.
Terravista Lakes Development Drainage Impact Analysis, Fort Bend County, Texas - A
linear detention system was designed for the proposed subdivision located immediately south of
the Long Point Slough (Clodine Ditch) downstream segment. The detention capacities and the
storm sewer facilities were designed and evaluated to mitigate the impact to the Long Point
Slough peak flows and maximum flood elevations downstream of the subdivision outfall channel
conjunction.
Sprint Fort Bend County Landfill LOMR and CLOMR Requests and Drainage System
Design for Permit Application - This project redefined the Red Gully floodplain and floodway
limits within the Sprint Fort Bend County Landfill property based on improved topographic data.
As a result, an existing sand pit and the planned sand pits may be removed from the floodplain
and used for future landfill operations. Chen-hua performed the flood study and designed a
peripheral drainage system for the landfill according to the proposed future topography. The
drainage system includes collection swales, chutes, surrounding ditches, and four detention
ponds. Storage mitigation for floodplain and wetland losses were also accounted for.
Colorado River Decision Support System – Chen-hua developed the SAMS (Stochastic
Analysis, Modeling, and Simulation) software package by using the Microsoft Visual C++ and
Fortran Powerstation, which was then used to generate the multivariate monthly flow sequences
for the Colorado River system to detect the optimized water use and distribution policy.
Brickhouse Gully Channel Improvement/Restoration Impact Analysis, Harris County,
Texas - This project evaluated three alternatives for the proposed Brickhouse Gully channel
improvement from the BNSF Railroad Bridge near Watonga Blvd. to Costa Rica Road with
consideration of a proposed regional basin located at the confluence of Brickhouse Gully and
the Tributary E115-04-00, immediately upstream of US 290. The three alternatives include (1)
repair and retain the existing channel section, (2) replace the existing section with a standard
trapezoidal section consisting of a 20-foot bottom width and 2:1 side slopes, and (3) replace the
existing channel with a trapezoidal section consisting of an 8-foot bottom width and 2:1 side
slopes. Chen-hua used the modified TSARP White Oak Bayou HEC-HMS and Brickhouse
Gully HEC-RAS models to evaluate these alternatives. The analysis results indicate that the
regional basin has no significant effect on the White Oak Bayou flood hazard conditions, and
that restoration of the original channel section is recommended.