High-altitude regions offer several challenges for the management of surface and subsurface water resources, due to their unique weather patterns, geology and topography. In this survey of mountain region hydrology, the assessment, dynamics and modeling of glaciers, rivers and lakes is explained in detail, and the impact of climate change and anthropogenic activities on the mountain ecosystem is analyzed. Challenges for the sustainable management of water resources are discussed, focusing on water yield, water quality and the risk of flash floods. Numerous case studies from the Himalayas are included, which serve as a model region for both medium-high and very high altitude water resources. The final section of the book looks at traditional methods of water resource management and conservation, and their importance for 21st century strategies.