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<br />From TSARP models flow at Spencer Bridge is 2,730 (cfs) and increases to 3,264 (cfs), <br />an increase of 437 (cfs), between Bandridge Road and the confluence with BIl2-02-00 <br />due to full development contributing runoff to the channel. Downstream of the <br />confluence with BI12-02-00 flow increases to 3,429 (cfs), an increase of 165 (cfs). <br />Within the reach between Spencer Highway and Bl12-02-00, Willow Springs Gully is at <br />bank: full conditions, causing flooding in Brookglen for the 100-year even. <br /> <br />Channel velocities from north of Spencer Road to just north of Bandridge bridge are <br />approximately 5.9 fps and consistent from one cross section to the next within the reach <br />which indicates the channel is at normal depth. The cross section north of the confluence <br />indicates an increase in the velocity to 8.5 fps associated with the increase of 437 (cfs) in <br />flows for a total flow of 3,264 (cfs). The cross section remains unchanged until this area. <br />Differences between the energy grade and water surface in this reach ranges between <br />0.52 ft and 1.12 ft. <br /> <br />Downstream of the confluence, flows in the channel increases to 3,429 (cfs) in the larger <br />cross sectional area of the 20-foot wide low flow section with a velocity of 6.5 fps. Just <br />down stream velocities drop between 3.7 fps and 4.4 fps with additional increases in flow <br />through the grass lined channel section. Differences between the energy grade and water <br />surface in the grass lined section average 0.25 ft and 0.66 ft in the concrete section down <br />stream of the confluence. <br /> <br />4.3 Confluence of B112-00-00 with B112-02-00 <br /> <br />Flow upstream and downstream of the confluence is close to normal depth or about 12.5- <br />feet for the 100-year event. The normal depth discharge in BIl2-00-00 upstream and <br />downstream of the confluence is similar for the same normal depth of l2.5-feet. With <br />this logic, flows were calculated for 4-feet to measure the effects of the confluence <br />configuration on tributary BIl2-02-00 using empirical formulas. The 4-foot depth was <br /> <br />4-2 <br /> <br />Klotz Associates Project No. 0127.009.000 <br />May 2009 <br /> <br />Fairmont Park East & Brookglen Drainage Study <br />City of La Porte <br />