This book draws on the author’s professional experience and expertise in humid and arid regions to familiarize readers with the basic scientific philosophy and methods regarding floods and their impacts on human life and property. The basis of each model, algorithm and calculation methodology is presented, together with logical and analytical strategies. Global warming and climate change trends are addressed, while flood risk assessments, vulnerability, preventive and mitigation procedures are explained systematically, helping readers apply them in a rational and effective manner. Lastly, real-world project applications are highlighted in each section, ensuring readers grasp not only the theoretical aspects but also their concrete implementation.