Historical maps and aerial photographs Sample Clauses

Historical maps and aerial photographs. An analysis of historical maps and aerial photographs will provide information on the position of the river channel in the past, the rates of channel migration, the impact of large floods, and human activities that have altered the channel. A preliminary analysis of topographic maps indicates that much of the channel was artificially straightened at some point in the past (possibly in the 1800s) and that the channel has reestablished meanders along certain sections during large floods. Straightened channels are typically unstable during large floods and are prone to the development of meanders along their length. The historical maps and aerial photographs can document this past straightening and in conjunction with the bank mapping can identify potential locations where future meanders might be likely to develop along these straightened channels. Identifying sections along the river where meanders could be encouraged to form could help create aquatic habitat in selected areas while reducing the threat of meander development in areas near highly valued infrastructure.