River management and conservation issues on formerly braided river systems; the case of the River Tay, Scotland

Although the present-day River Tay, Scotland is generally confined to a single course and exhibits limited lateral mobility, historical maps (1747–53) reveal that during the eighteenth and nineteenth centuries a braided river channel pattern was more characteristic of a number of reaches on the piedmont valley floor. Possible explanations of the change in channel pattern include flood embankment construction, flow regulation by impoundment and possibly a change in flood magnitude and frequency, and alterations in sediment supply.
Areas of former braiding isolated from the main channel by embankments or incorporated into the floodplain sediments, exhibit a greater susceptibility to erosion and are prone to flood embankment breaches. In contrast, river channel reaches still exhibiting unconfined braiding tendencies have been designated areas of high conservational value due to large expanses of gravel at different stages of vegetation colonization and high plant species diversity.
It is suggested that the identification of areas of former braiding and reaches prone to braiding is useful for land use management both for improved flood protection and floodplain habitat conservation.