Water is the essential element that all life-forms on our planet are dependent on. It is impossible to assess its value because it is equal to the life itself. Humans realized this fact long time ago and they always endeavored to control and manage water resources as they were afflicted by the drought and flood events throughout history. Therefore, the engineering of water resources and hydraulic structures is as old as the human civilization. The earliest known engineered irrigation system was developed in ancient Mesopotamia (Iraq); an advanced system of dikes, dams and canals was built for the purpose of irrigation and flood control. The main water sources for this system were the rivers Euphrates and Tigris. During plant growing seasons, the flow of water was properly regulated. Each farmer was allowed a certain amount of water, which was diverted from the canal into an irrigation ditch. The oldest known engineering plan of such an irrigation system has been documented on some unique and ancient clay tablet which has been discovered in Babylonia (belonging to 1684-1647 BC). It shows a map of canals with cuneiform scripts providing details about names, lengths, widths and depths of the canals and the volume of sediment to be dredged. Mesopotamians have acquired the expertise of maintaining their irrigation system over thousands of years. This contribution was a major step toward the modernization of humanity. The Water Research Center (located in Iraq), which is dedicated to the exchange of knowledge and technology in the water sector, has been inspired by those ancient engineers, hence published this book series entitled "Progress in River Engineering & Hydraulic Structures." It is intended to be a worldwide platform for the contemporary research in this field. Chapters of this series demonstrate the stringent need for new solutions and technologies in the subject of river engineering and hydraulic structures. The chapters cover a wide range of problems related to river regime and training works, performance of different kinds of hydraulic structures and any related multidisciplinary research. We believe that through the collaboration of researchers, engineers and professionals, we can accelerate the development in these areas. The book is aimed to serve as a reference for both researchers and postgraduate students.