Explain the Variable Conditions of River Flow and Health State?

The variable conditions of river flow and health state of structure demands constant supervision.  Although scour may occur at any time, it is significantly more intense during floods and storms when stronger currents are generated, allowing more sediment to be carried away down stream.  It is, therefore, necessary that structures with foundations that are subjected to erosion scour be inspected just after the storms that result in flooding and strong currents Bridge scour evaluation should be conducted for each bridge to determine whether it is scour critical.  Scour critical bridge is one with abutment or pier foundations which are rated as unstable due to

(1) observed scour at the bridge site, or

(2)  a scour potential as determined from a scour evaluation study.