River Engineering and Flood Protection

Streams passing through seƩlements oŌen cause flooding, as a result of rapid urbanization in our country. The main reasons are; the growth of surface flow coefficients due to increasing urbanization and concretion and creating larger surface flows by rains of the same intensity, the occupation of river floodplain due to illegal construction and the change in river morphology by increasing the water level.

There are similar problems in rural rivers. Significant changes in river morphology due to rapid destruction of forests, inaccurate farming applies, removal of sand from river beds prepare the ground for floods.

Suddenly changing of high flow or water level, which may cause damage to property and life, can be called flood. Flood damages are direct or indirect damages, caused by flood waters and their solids, in life, goods and services. Flood control is a set of activities in order to reduce or completely prevent flood damages. In doing so, the design of the structures provides protection against the flood that is most likely to occur, provided that it is within acceptable costs.

Several measures are available in order to reduce or prevent flood damages. Flood damages can be avoided by measures such as preventing and allowing only certain activities in the flood area, planning rescue and evacuation activities, temporarily evacuating or isolating the flood area, lowering the bed base by stream arrangement or increasing cross section speed, flood delaying pools, dividing flood waters by flood canals, to reduce flood peak flows by holding back some of the flood water with deposition facilities such as flood detention dams and dams, with the help of berms, flood walls or closed mediums keeping flood areas in a certain flood bed.

Stream reclamation projects are the projects that should be carried out in order to collect all rain water in the regions where storm drainage systems have been completed and transport them to the sea. However, the wastewater in the seƩlements is unfortunately discharged to the streams and the streams cause pollution of the environment.

For this reason, it has been a necessity of modern engineering to plan the green areas and service roads on both sides of the stream as sewer lines that will collect the waste water on both sides of the stream and the breathing areas of the city as well as the stream that will drain the rain water.