(1) Estimate the peak runoff rate by the SCS TR-55 method from information provided above. Make reasonable assumptions, if any. (2) Follow the design guidelines for the vegetated waterways. After the design parameters are estimated, provide step by step method for construction until completion of the waterway installation with all recommendations for each item necessary for the contractor to build it.
Design a 4:1 trapezoidal shaped vegetated waterway for a field in Sangamon County, Illinois for the given condition. The highest rainfall occurs during growing season after several days of dry period (antecedent rainfall condition is I). Hydrologic soil group is B. The grass waterway is designed to carry peak runoff rate from a 100-ha watershed, which has row crops on terraced lands with poor hydrologic condition, maximum length of flow is 500 m, and average watershed slope is 3%. The soils are highly erodible, and the waterway slope is about 4.5%. The vegetation is usually mowed (retardance group D), but the waterway should have adequate capacity when the grass is tall (retardance group B). Design for both cases. Provide final dimensions of top width, depth, and bottom width of the waterway. If any data is missing, make reasonable assumptions. (1) Estimate the peak runoff rate by the SCS TR-55 method from information provided above. Make reasonable assumptions, if any. (2) Follow the design guidelines for the vegetated waterways. After the design parameters are estimated, provide step by step method for construction until completion of the waterway installation with all recommendations for each item necessary for the contractor to build it. What vegetation is used in your design
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