Climate Change Impact on the Hydrology of Spencer Creek Watershed
Use of Watershed Hydrology to Estimate ... - dig.erdc.dren.mil
1
Use of Watershed Hydrology to Estimate Deep-Draft Dredging Requirements Elissa Yeates*, Ahmad Tavakoly, Greg Dreaper, Kenneth Mitchell (all U.S. Army Corps of Engineers, Engineering Research and Development Center, Coastal and Hydraulics Library), and Shahab Afshari (City College of New York, Department of Civil Engineering). *POC: [email protected] On average, the United States Army Corps of Engineers (USACE) contracts nearly a billion dollars per year for navigation channel maintenance dredging. Due to limited funding amounts Corps-wide, USACE dredging managers must determine the extent to which navigation channels are to be maintained in a given budget year. Anecdotally and through experiential knowledge, Corps Navigation project managers know that dredging requirements will increase in the years following one or more major precipitation events in the associated watershed. This study uses the Streamflow Prediction Tool (SPT), a runoff routing model based on global weather forecast ensembles, to estimate dredging requirements by channel segment. Regression relationships between historical streamflow volumes and resulting dredged sediment volumes are used to estimate the relationship between these quantities for each watershed. Results in the test cases of the Houston Ship Channel and the Sabine and Port Arthur Harbor waterways in Texas indicate positive correlation between the calculated streamflows and subsequent dredging requirements. Inland hydrology impact on channels Texas coastal sites For this analysis, we took advantage of several USACE data sets and tools. Our streamflow time series for selected reaches was downloaded from the SPT. The historic dredging data came from the USACE Galveston District, and was plotted spatially using the USACE National Channel Framework GIS database. We processed these inputs via R scripting to match streamflow time series with dredged volume time series at the river reach level. We performed regression analysis of dredged volumes as a function of precipitation-driven streamflow in R, and created an online mapping tool to store the results spatially. For initial investigation of the link between cumulative streamflow and dredging volumes, we selected three study areas in Texas Gulf Coast Regions: Sabine and Port Arthur Harbor, the Houston, Galveston, and Texas City Harbor system, and Corpus Christi Harbor. We selected these test sites to represent a wide range of Texas coastal riverine systems, and to take advantage of available dredging records and calculated stream flow time series. Within these study areas, specific channels were chosen for analysis. Methodology Results – Sabine Neches Results – Houston Ship Channel Study Area Stream ID Drainage Area, square km Number of dredging events R-squared value Sabine Neches 1112455 25,931 11 0.42 1115825 26,058 9 0.36 1477515 26,064 15 0.00 1477595 26,220 15 0.26 1477713 26,204 12 0.48 1477589 26,215 16 0.29 1477725 26,201 11 0.55 1481563 27,705 23 0.17 24719331 53,730 12 0.02 Houston Ship Channel 1440485 1,192 8 0.14 1440511 2,012 8 0.32 1440521 2,578 6 0.10 1440525 1,205 9 0.93 1440539 1,578 10 0.33 Corpus Christi Harbor 1432855 15 2 NA - 2 events 1636549 2 2 NA - 2 events 3172512 43,334 4 0.00 The average R squared value for the examined Houston Ship Channel reaches is 0.36, slightly higher than the average R-squared value for the Sabine Neches reaches, 0.28. Stream reaches that performed best when comparing dredged volumes to cumulative flow were generally upstream of bays and lakes. This is likely due to coastal effects on sediment deposition, which are not addressed in the flow rates generated by the SPT. Results – Summary of test sites
Transcript of Use of Watershed Hydrology to Estimate ... - dig.erdc.dren.mil
Use of Watershed Hydrology to Estimate Deep-Draft Dredging Requirements
Elissa Yeates*, Ahmad Tavakoly, Greg Dreaper, Kenneth Mitchell (all U.S. Army Corps of Engineers, Engineering Research and Development Center,Coastal and Hydraulics Library), and Shahab Afshari (City College of New York, Department of Civil Engineering). *POC: [email protected]
On average, the United States Army Corps of Engineers (USACE) contractsnearly a billion dollars per year for navigation channel maintenancedredging. Due to limited funding amounts Corps-wide, USACE dredgingmanagers must determine the extent to which navigation channels are tobe maintained in a given budget year. Anecdotally and throughexperiential knowledge, Corps Navigation project managers know thatdredging requirements will increase in the years following one or moremajor precipitation events in the associated watershed. This study usesthe Streamflow Prediction Tool (SPT), a runoff routing model based onglobal weather forecast ensembles, to estimate dredging requirementsby channel segment. Regression relationships between historicalstreamflow volumes and resulting dredged sediment volumes are usedto estimate the relationship between these quantities for eachwatershed. Results in the test cases of the Houston Ship Channel and theSabine and Port Arthur Harbor waterways in Texas indicate positivecorrelation between the calculated streamflows and subsequentdredging requirements.
Inland hydrology impact on channels
Texas coastal sites
For this analysis, we took advantage ofseveral USACE data sets and tools. Ourstreamflow time series for selectedreaches was downloaded from the SPT.The historic dredging data came from theUSACE Galveston District, and was plottedspatially using the USACE NationalChannel Framework GIS database. Weprocessed these inputs via R scripting tomatch streamflow time series withdredged volume time series at the riverreach level. We performed regressionanalysis of dredged volumes as a functionof precipitation-driven streamflow in R,and created an online mapping tool tostore the results spatially.
For initial investigation of the linkbetween cumulative streamflow anddredging volumes, we selected threestudy areas in Texas Gulf CoastRegions: Sabine and Port ArthurHarbor, the Houston, Galveston, andTexas City Harbor system, andCorpus Christi Harbor. We selectedthese test sites to represent a widerange of Texas coastal riverinesystems, and to take advantage ofavailable dredging records andcalculated stream flow time series.Within these study areas, specificchannels were chosen for analysis.
Methodology
Results – Sabine Neches
Results – Houston Ship Channel
Study Area Stream IDDrainage
Area, square km
Number of dredging
events
R-squared value
Sabine Neches
1112455 25,931 11 0.421115825 26,058 9 0.361477515 26,064 15 0.001477595 26,220 15 0.26
1477713 26,204 12 0.48
1477589 26,215 16 0.29
1477725 26,201 11 0.55
1481563 27,705 23 0.1724719331 53,730 12 0.02
Houston Ship
Channel
1440485 1,192 8 0.141440511 2,012 8 0.321440521 2,578 6 0.101440525 1,205 9 0.931440539 1,578 10 0.33
Corpus Christi Harbor
1432855 15 2 NA - 2 events
1636549 2 2 NA - 2 events
3172512 43,334 4 0.00
The average R squared valuefor the examined HoustonShip Channel reaches is 0.36,slightly higher than theaverage R-squared value forthe Sabine Neches reaches,0.28. Stream reaches thatperformed best whencomparing dredged volumesto cumulative flow weregenerally upstream of baysand lakes. This is likely dueto coastal effects onsediment deposition, whichare not addressed in the flowrates generated by the SPT.
Results – Summary of test sites
