River engineering works are aimed at the control of the water and sediment discharges, bank erosion, channel depth, floodplain area and water quality. This control can be achieved by the use of various structures, used alone or in a combined way, such as check dams, reservoirs, levees and floodwalls, locks, bank revetments, channel contraction and other control works. The choice of the most adequate river engineering work is not straightforward and can then be made only after careful hydraulic, economic, social and environmental analyses. The river engineering structures, if not properly designed and built, can cause opposite effects to those expected during the design phase. Infact, structures are often selected and installed without an understanding of the sediment transport processes, thus violating the dimension, pattern and profile of the stable river. This book reports the results of a research work, aimed at the study of the check dam operation, with particular emphasis to the filling process.