Water resources play an essential role in all aspects of human life and activities. All living organisms need water for survival. Due to increased demand for water, appropriate water resources management should be established. This book covers various aspects of water resources management, including their use for different purposes and impacts of natural factors and anthropogenic pressures on water resources. Climate changes affect water resources, causing floods and droughts. All human activities such as water supply, irrigation, navigation, hydropower, tourism and recreation use water resources. The natural and anthropogenic impacts cause a decline in water quantity and the degradation of water quality. Water resources are especially important in protected areas and management of them in these areas is a specific challenge. Adequate water resources management should address all water related issues, to establish an institutional and legal framework, as well as the cooperation of all relevant actors in this field at national and international level. Water reuse, such as wastewater management is also an important challenge. This book provides some models and methods which are used for water resources estimation, their vulnerability and exposure to natural and anthropogenic influences. Taking into account various aspects of water related topics, application of diverse models and methods in different geographical areas, the book Water Resources Management: Methods, Applications and Challenges could help policy and decision makers as well as other stakeholders in finding the solutions of some water related problems.