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Peak discharge of Crane Creek at the US 395 Culvert for a 100-year Precipitation Event.
CE 413 School of Civil and Construction Engineering Oregon State University 3/12/2021
Submitted by Ryan Giammona Full report can be accessed at:
https://sites.google.com/oregonstate.edu/ryan-giammona/home Giammona 2
Introduction: Oregon department of transportation requests that the water flow path through an existing culvert at the intersection of Crane Creek and US 395 be redesigned to prevent highway overtopping and to reduce the amount of sediment that clogs the existing flow path. The source of water flow through the site is Crane Creek, which collects water from the surrounding Crane Mountain watershed, and is a tributary to Goose Lake. The culvert redesign must address the given issues to help prevent the flooding of nearby private properties and the overtopping of the ODOT-owned highway 395. Possible considerations for this project include culvert size, layout and placement, sediment management, fish passage, temporary water and traffic control, construction staging, roadside safety, and roadway geometric design. Foreseeable challenges facing this project are that the site is located within a FEMA flood plain, sediment management, a shallow elevation of the existing highway with respect to the stream bed, and design restrictions due to budgetary restraints. The primary objective of this project is to protect Highway 395 from flooding by designing a new culvert crossing, accounting for sediment passage, and allowing for fish passage, all while limiting the flooding to nearby private property barnyard. The proposed design entails the retirement of the existing culvert, and addition of a culvert approximately 300ft north of the existing site running under US395. The approach to this design must be cost-effective, and consider environmental/safety challenges. The first stage of the project will require the determination of peak discharge for a 100-year discharge event per ODOT hydraulics manual. This report will detail the determination of the 100-year peak discharge based on the NRCS graphical method with information derived from publicly available raster data interpreted using ArcGIS pro.
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Site Description: The location of this site is on a stretch of US 395 (Fremont Highway), about 5 miles south of Lakeview, Oregon, as shown in the site map below in figure 1.
The crane mountain wateshed draining into the existising culvert is approximantly 8364 acres, located east of the existing culvert location. The forested portion of the watershed lies on the western slopes of Crane Mountain and the upper lopes of the Camas Creek drainage in the Warner Range. The eastern slopes of Crane Mountain are influenced by the rain shadow effects of the mountain's elevation; 8,456 feet at its highest point. The mountain is comprised a series of north to south running ridges separating Goose Lake Valley from the eastern Oregon high desert.The upper eastern slope of Crane Mountain above 8,000 feet is generally above tree line and subject to harsh winter conditions. Slopes just below 8,000 feet are generally subalpine consisting of open meadows and white barked pine. See Figure 2 below for view of watershed.
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Data: USGS NED n43w121 1/3 arc-second elevation model was downloaded for the USGS The National Map Downloader as a raster with 1/3 arc second resolution in with the NAD 1983 Geographic coordinate system The US soils hydraulic properties raster was downloaded from the ERSI live atlas. The projected coordinate system is WGS 1984 Web Mercator and has a 30M resolution. The US Vegetation land cover properties raster was downloaded from the ERSI live atlas. The projected coordinate system is North America Albers Equal Area Conic and has a 30M resolution The Nation Hydrology Dataset stream data was downloaded for the USGS The National Map Downloader as vector information with the NAD 1983 Geographic coordinate system.
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Methodology: ArcGIS pro was used to determine watershed area, and to determine hydraulic properties of the area. The first stage was to determine the watershed area. Once the DEM model was downloaded the first step was to run the run the fill tool on the DEM to smooth any sinks or irregulates that may have occurred within the DEM The next stage was to run the flow direction tool on the fill DEM to the direction of flow from each cell to its steepest downslope neighbor. Then the next stage was to run the Flow Accumulation tool, this calculates the accumulated flow to each cell, as determined by the accumulated weight of all cells that flow into each downslope cell. Then new layer with a single pour point at the culvert was created and placed directly on the cell where the flow accumulation was traced for crane creek. Then the watershed tool was used to determine all watershed stream of the pour point location. This raster was transformed into a polygon and determined to have an area of 8364 acres. The DEM raster was clipped to the size of the watershed polygon for future use,
The following information was needed for the NRCS graphical method peak flow equation. Average slope: The average slope was determined by using the slope function on the clipped DEM to determine slope, the statics of this raster showed a mean slope of 27 degrees.
Y= 27.1 Degrees
Average Soil type: The US hydraulic soils map clipped to the watershed size showed 5 soil types within the watershed. The count is the number of cells to provide an estimate of average soil type to be used to find the curve number.
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Vegetation Cover: The US vegetation land cover map clipped to the watershed siz and showed 2 vegetation types within the watershed. The count is the number of cells to provide an estimate of average vegetation type to be used to find the curve number.
The Resulting data can be used to determine the watersheds curve number based on the NRCS graphical method:
(79 ∗ (69%) + 73 ∗ (30%)) + (32(69%) + 35(30%)) 퐶푁 = = 54.5 2
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Precipitation: Precipitation data for this areas was acquired through the ODOT REGIONAL PRECIPITATION-FREQUENCY ANALYSIS as seen in figure 3.
Figure 3. Oregon 24-hour, 100 year Precipitation map(ODOT REGIONAL PRECIPITATION FREQUENCY ANALYSIS) The value was determined to be P= 3.25 inches Based on the NRCS map 2-1, crane creek classifies as Type: II rainfall
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Figure 4. NRCS Rainfall type Area: The area was calculated to be approximately 8364 acres in the watershed polygon.
Am=8364 acres= 13.1 square miles
Watershed Length: watershed length was calculated using the measure tool to determine the distance from the furthest extend to the culvert. L= 295276 feet
The resulting information was used to determine the time of concentration
0.7 1000 (2952760.8 ∗ ( − 9)) 54.5 푇푐 = = 0.932 1140(27.06)0.5
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Using Table 4-1 from NCRS Ia is calculated based on curve number
퐼푎 = 1.636 퐼푎 1.636 = = 0.501 푃 3.25 𝑖푛푐ℎ푒푠
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Ia/P and Tc values are then used in the NRCS Peak Unit discharge graph to determine qu .
퐶퐹푀 푞푢 = 160 𝑖푛푐ℎ Giammona 12
Precipitation value and the Curve number are then used the runoff equation grao to determine direct runoff values.
푄 = 0.2 𝑖푛푐ℎ푒푠 Giammona 13
Peak Discharge qp can then be determined using the following information. qu= 160 CFM/inches
Am=13.1 square miles Q= 0.2 Inches
Pond/swamp factor Fp = 1.0 (since there are no swamps or ponds located within the watershed)
퐶퐹푀 푞 = (160 ) (13.1 푚𝑖2)(0.2 𝑖푛푐ℎ푒푠) = 419 퐶퐹푆 푝 퐼푛푐ℎ푒푠 The peak discharge of Crane creek at the US 395 culvert is approximately 419 Cubic Feet per second per the NRCS Graphical Peak Discharge Method.
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Flowchart:
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Results: The results of this report demonstrated a estimated peak discharge during a 100 year precipitation event to be 419 cubic feet per second according to the NRCS graphical method. USGS stream gauge # 11341200 approximately is 2.25 miles upstream (figure 4) has determined the 100-year flood flow to be 346 CFS. This verifies the estimation of 419 cubic feet per second is reasonable and slightly than the USGS gauge report due to the fact that there is roughly 1.3 square miles of catchment area between the USGS stream gauge and the US 395 culvert.
Figure 4. Illustrating location of USGS stream Gauge #11341200 This Report does not account for potential effects of snow on steam flow and assumes all precipitation fall in the form of rain. With much of the area receiving snowfall during the winter months, snow accumulation likely has a large effect on steam flows weather it be freeze/thaw cycles or large thaw events for areas above the tree line which likely cause heavy flows into crane creek A further study may analyze the effects of snow accumulation and rapid snow melt and take those effects into consideration. The culvert also lies within the FEMA 100-year flood zone and may be affected by stream bank overtopping during large storm event as shown in the small dark green section fig 5. These events may cause overtopping of the stream banks and effect stream properties but should not affect the flow of Crane creek.
Figure 5. FEMA 100-year flood zone Giammona 16
Appendix:
“Module 206 A - Time of Concentration .” National Resource Conservation Service, USDA,
“Module 206 B Peak Discharge (Graphical Method, TR-55) .” National Resource Conservation Service USDA,
Oregon Department of Transportation Research Unit. (2008). “REGIONAL PRECIPITATION- FREQUENCY ANALYSIS AND SPATIAL MAPPING OF 24- HOUR PRECIPITATION FOR OREGON Final Report .” Oregon Department of Transportation (Mar. 11, 2021).
“USGS Maps.” Overview - Maps US Geological Service, USGS,