Field Observations and One-Dimensional Flow Modeling of Summit Creek in Mack Park, Smithfield, Utah

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1 Intermountain Center for River Rehabilitation and Restoration, Utah State University 31 July 2018 Field Observations and One-Dimensional Flow Modeling of Summit Creek in Mack Park, Smithfield, Utah I. Goals for learning and discussion: A. Learn to use HEC-RAS, by building a working steady state model B. Learn the relation among model inputs, model-derived outputs, and actual field conditions C. After this session, students will be able to construct a basic HEC model and will be ready to learn how to tackle more complicated modeling scenarios. II. Activity: After eating lunch, we will walk along the channel and identify the locations of channel crosssections and bed material counts. Your observations will be useful when you return to the class room and build the model. Background: Summit Creek is a small tributary of the Bear River that drains part of the Bear River Range. Mack Park is a 13-ac tract that was deeded to Smithfield city in Originally, the area was referred to as the Grove because of the trees, willows, and shrubbery (Smithfield Historical Society, 2001). The map of the park from 1934 depicted a heavily wooded area around the stream. The stream was shown approximately at the same location as it is today. The present landscape of the park was created in the late 1970s following numerous complaints about rowdy parties and misuse. Diseased and dead trees were removed. Unsightly underbrush and willows were cleared away from the creek banks. The city crews graded some of the areas and riprapped the banks of the creek. New trees and grass were planted where needed. The completed project cost about $10,000 (Smithfield Historical Society, 2001). Comparison of the location of today s channel with that of 1934 indicates that some degree of realignment occurred during these construction activities. Stream flow The USGS operated gaging station between 1961 and 1979 approximately 4 mi upstream from the park (Fig. 1) where the drainage basin area is 11.6 mi 2. The mean annual flow for this period was 19.8 ft 3 /s and varied over a three-fold range between 8.1 and 29.1 ft 3 /s (Fig. 2). The largest flood of the gaging period was 302 ft 3 /s and occurred May 23, This flood was approximately 15 times larger than the mean annual flow. The 2-yr recurrence flood is approximately 145 ft 3 /s, which is approximately 7 times larger than the mean annual flow. Flood frequency analysis indicates that the 1.5-yr recurrence flood at the gage is approximately 76 ft 3 /s and that the 2-yr recurrence flood is 149 ft 3 /s (Fig. 3).

2 Stream flow through the park has two origins: natural flood flows generated from the watershed and base flows derived from irrigation return flows from canals. There are three diversions of stream flow between the USGS gage and Mack Park (Photo 1), and most base flows are diverted from the stream. The base flows that you observe are primarily derived from water that is not diverted and flow that enters the stream from the Logan, Hyde Park, and Smithfield Canal originally diverted from the Logan River. In contrast, flood flows are typically derived from the Summit Creek watershed, because they occur at a time when diversions are minimal. There is no regular measurement of stream flow in the park. We have developed a stage-discharge rating relation. Over a stage range of approximately 1.8 ft, discharge varies between approximately 0 and 129 ft 3 /s (Fig. 4). Geomorphology The water surface slope through the park is between and , depending on the stage at which measurements are made (Fig. 5). The reach within 30 m upstream from the lower concrete bridge is the steepest part of the profile. The bed material of the channel is highly variable, because many blocks or rip rap have now fallen into the channel and contribute to hydraulic roughness. Thus, we completed two bed material counts (Fig. 6) that were isolated to specific bars in the park, located in Figure 7. In addition, we completed one surface material count that averaged bed material of the entire channel between cross-sections 8 and 18, one surface material count from Canyon Road to Middle Bridge (Fig.7), one surface material count that averaged the reach between the middle and downstream bridges, and one count that characterized the average bed material size upstream from Canyon Road. We also completed one subsurface bed material count at gravel bar 2 in the park. Since bed material size, bed material organization, bank material, and plan form all contribute to hydraulic roughness, you should observe channel conditions as you walk around. Examine the example cross-sections shown in Figure 8 and note the edges of the active bed, bank material, and the sloping grassy surfaces of the park. You will need to identify the edges of the bank when building your HEC-RAS model and so your field notes will be useful later today. HEC-RAS modeling exercise When you return to the classroom, you are to build a HEC-RAS model of Summit Creek between cross-sections 1 and 18. The cross-section data, including the distance between cross-sections, are included in an Excel file.

3 Summit Creek, Smithfield, Utah Photo 1. Diversion on Summit Creek, about 0.7miles upstream from Mack Park. July 8, 2008 (~ 2.62 ft 3 /s) June 8, 2009 (~ 130 ft 3 /s) August 4, 2009 Photo 2. Stream character upstream from Mack Park

4 Summit Creek, Smithfield, Utah June 8, 2009 (~ 130 ft 3 /s) August 4, 2009 July 8, 2008 (~ 2.62 ft 3 /s) Photo 3. Stream character in Mack Park. July 8, 2008 (~ 2.62 ft 3 /s) August 4, 2009 Photo 4. Change of river bed in Mack Park.

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12 Figure 8 Example cross-sections, Summit Creek at Mack Park 99 Summit Creek XS-1 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum a) 99 Summit Creek XS-2 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum b)

13 100 Summit Creek XS-11 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum c) 100 Summit Creek XS-12 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum d)

14 101 Summit Creek XS-17 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum e) 101 Summit Creek XS-18 Elevation, in meters, above an arbitrary datum Distance from left endpoint, in meters, from an arbitrary datum f)