4 <strong>Stream</strong>-<strong>Profile</strong> <strong>Analyses</strong> <strong>Using</strong> a <strong>Step</strong>-<strong>Backwater</strong> <strong>Model</strong> <strong>for</strong> Selected Reaches in the Chippewa Creek Basin in Ohio The Chippewa Subdistrict is concerned about the impact that existing and future development and channel conditions will have on the hydraulic and hydrologic characteristics within the watershed. To aid in the assessment of these impacts and to assist communities making land-use and development decisions, the Chippewa Subdistrict requested that the U.S. Geological Survey (<strong>USGS</strong>) develop a step-backwater model <strong>for</strong> selected reaches of Chippewa Creek, Little Chippewa Creek, and River Styx. Description of Study Area The Chippewa Creek basin (fig. 1) is located in northeast Ohio, largely in Medina and Wayne Counties but also in small portions of Summit and Stark Counties. The Inlet, which is the headwaters of Chippewa Creek, is a roughly 2-mi reach of stream located west of the city of Medina, and it flows into Chippewa Lake. Chippewa Creek flows out of Chippewa Lake, the largest natural lake in Ohio. Chippewa Creek generally flows south through south-central Medina County, through the village of Seville, and into Wayne County. After flowing through Sterling, Chippewa Creek flows east, passing through the southern edge of the city of Rittman, and eventually flows into the Tuscarawas River in southwestern Summit County (fig. 4). Near the outlet of Chippewa Lake, some of the flow in Chippewa Creek escapes into the headwaters of Westfield Ditch, a tributary of Chippewa Creek, and so Westfield Ditch was modeled as well. Little Chippewa Creek starts in Wayne County near the city of Orrville and generally flows north to join Chippewa Creek at the south side of the city of Rittman (fig. 4). River Styx begins in Medina County near Wadsworth and generally flows south into Wayne county, along the eastern edge of the city of Rittman, and joins Chippewa Creek at the southeastern side of Rittman (fig. 4). The entire Chippewa Creek basin covers 188 mi 2 , with Little Chippewa Creek covering 32.2 mi 2 and River Styx covering 29.6 mi 2 . The Chippewa Creek basin is largely agricultural, and a majority of the basin is used <strong>for</strong> cultivated crops, pastures, and hay. In cities and villages, a majority of the development is of low intensity or is considered open space (U.S. Geological Survey, 2001). The 2009 population estimates, according to the U.S. Census Bureau, are 174,035 in Medina County and 114,222 in Wayne County. The <strong>USGS</strong> currently operates one streamflow-gaging station in the Chippewa Creek basin (fig. 1). That station, Chippewa Creek at Miller Road at Sterling, Ohio (<strong>USGS</strong> 03116077; fig. 4), was installed in 2002, and data collected by it was used to calibrate the model <strong>for</strong> Chippewa Creek. Two other streamflow-gaging stations were operated in the Chippewa Creek basin but have been discontinued: Chippewa Creek at Easton, Ohio (03116200), operated from 1959 to 1981, and Little Chippewa Creek near Smithville, Ohio (03116100), operated from 1957 to 1972 (fig.1). Data from these stations were not used to calibrate the model because the stage-discharge relationships have changed over the years. Flood-Control Modifications The SCS built structures and modified channels to mitigate the effects of flood flows, as listed in the Chippewa Subdistrict’s Official Plan (Muskingum Watershed Conservancy District, 1961). Sections of Chippewa Creek, Westfield Ditch, Little Chippewa Creek, and River Styx were modified to increase conveyance of flood flows by straightening and modifying the channels. The modifications called <strong>for</strong> a trapezoidal cross section, and the dredged materials were removed from the channel and distributed along the tops of the banks. The embankments <strong>for</strong>med from the dredged materials increased the main-channel cross-sectional area to convey greater flood flows and provided small impoundments behind the embankments <strong>for</strong> temporary storage. Any water storage behind the embankments drained back into the channel through small culverts or infiltration through the soil. All of the embankments and structures are within the MWCD jurisdiction. The plan also called <strong>for</strong> the construction of eight floodretention structures. All eight of the SCS flood-retention structures are located on tributaries to Chippewa Creek (fig. 1; table 1). Chippewa Lake is not considered one of the floodcontrol structures, although it provides some natural storage and flood attenuation. Structures II–A, III–A, IV–A, and V–D have conservation pools above the dam, but VIII–C, VIII–D, V–C, and VII–C are dry dams. The combined flood-storage capacity of all eight flood-control structures, not including the conservation pool storage up to the emergency crest, is 4,987 acre-feet (table 1). Purpose and Scope This report presents the methods used <strong>for</strong> and results of a study to analyze the hydrology and hydraulics of flow within channels of the Chippewa Creek basin to aid in an assessment of various flood-mitigation alternatives. The <strong>USGS</strong> used the Hydrologic Engineers Center’s River Analysis System (HEC-RAS; U.S. Army Corps of Engineers, 2008 a–c) stepbackwater model to develop water-surface profiles within selected streams in the basin (table 2) and the reach containing Chippewa Lake (fig. 4). <strong>Stream</strong>flows determined by use of the <strong>USGS</strong> Ohio <strong>Stream</strong>Stats program (U.S. Geological Survey, 2008) were used as estimates of bankfull flows in the models; cross-sectional elevation data, hydraulic structure geometries, roughness coefficients (Manning’s n), and peakdischarge estimates also were used as model inputs. Potential modifications to the channel were evaluated to determine their effects on water-surface elevations. The roughness coefficients (Manning’s n) of the main channel were then reduced by 5, 10, 15, and 20 percent to simulate potential effects of channel clearing and/or modifications on the water-surface profiles.
82°0'0"W 41°15'0"N 41°10'0"N 41°5'0"N 41°0'0"N 40°55'0"N 40°50'0"N 40°45'0"N Chippewa Rd Kennard Rd SR 604 / Buffham Rd MEDINA Westfield The Inlet Ditch MEDINA Chippewa Lake SR 224 SR 224 / I - 76 Greenwich Rd I - 71 Easton Rd EXPLANATION Chippewa Creek basin Municipal area Selected lake County boundary Selected stream Modified reach 81°55'0"W Wedgewood Rd SR 3 Chippewa Selected interstate or state route Selected county or township road Steiner Rd U.S. Geological Survey streamflow-gaging station and identifier Base from U.S. Geological Survey digital data, variously scaled State Plane Ohio North SR 3 SEVILLE 03116077 I - 71 STERLING Miller Rd 81°50'0"W Frick Rd Blake Rd Shorle Rd Little RITTMAN Chippewa Medina Wayne River Styx ORRVILLE WAYNE S Main St Creek 81°45'0"W Summit Creek Stark WADSWORTH 81°40'0"W SUMMIT SR 224 / I - 76 Greenwich Rd Introduction 5 Tuscarawas River STARK 0 5 10 MILES 0 5 10 KILOMETERS Figure 4. Map depicting selected features pertaining to the models of the Chippewa Creek basin in Medina, Wayne, Stark, and Summit Counties, Ohio.
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