Book excerpt: This book addresses most of the environmental impacts of sand mining from small rivers The problems and solutions addressed in this book are applicable to all rivers that drain through densely populated tropical coasts undergoing rapid economic growth. Many rivers in the world are drastically being altered to levels often beyond their natural resilience capability. Among the different types of human interventions, mining of sand and gravel is the most disastrous one, as the activity threatens the very existence of river ecosystem. A better understanding of sand budget is necessary if the problems of river and coastal environments are to be solved.