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<br />e <br /> <br />II. Back!!round <br /> <br />'J <br /> <br />Considerable research and development has been completed within <br />the past few years on temporary lining materials and rock riprap. <br />Combining that information with the applicable past research on <br />vegetative linings results in methods which cover most types of <br />flexible linings being used at present. An exception is that <br />wire enclosed rock gabions are not covered herein because no <br />appropriate design criteria is known to exist at present, <br />possibly because they are a proprietary product. If such <br />information becomes available, it can easily be inserted into <br />this design circular. <br /> <br />; <br /> <br />A more detailed discussion of the development of the curves and <br />design methods of this circular is presented in Appendix C. <br /> <br />Temporary Linings <br /> <br />Temporary linings are flexible coverings used to protect a channel <br />until permanent vegetation can be established using seeding. For <br />the most part, the materials used are biodegradable. <br /> <br />e <br /> <br />Research was completed at Mississippi State University (MSU) in <br />1968 (3) on bare soil and a variety of temporary lining materials <br />for the Mississippi State Highway Department, under the Highway <br />Planning and Research (HP&R) Program. Both the erosion prevention <br />capability and hydraulic resistance of various linings were determined <br />from the tests. The materials for which design information was <br />produced were: <br /> <br />1. Bare soil - ten soils ranging from cohesive clays <br />to non-cohesive sands and gravels. <br /> <br />2. Erosionet 315 - a paper yarn with openings <br />approximately 7/8-inch by l/2-inch. Normally <br />used to hold other materials such as straw. <br />Secured with steel pins. <br /> <br />. <br /> <br />'; <br /> <br />3. Jute mesh - a woven mat of coarse jute yarn with <br />openings about 3/8-inch by 3/4-inch. Held in <br />place with steel pins. <br /> <br />4. Stranded fiber glass roving with Erosion 315 - fine <br />glass fibers blown onto the channel bed using <br />compressed air and a special nozzle, and held in <br />place with steel pins and Erosionet (See No.2 above). <br /> <br />e <br /> <br />5. 3/8-inch fiber glass mat - a fine glass fiber mat <br />similar to furnace air filter material held in <br />place with steel pins. <br /> <br />3 <br />