Introduction

Abstract

Rivers, the most important life sustaining systems in tropics and subtropics, are under immense pressure due to various kinds of human interventions. Among these, indiscriminate sand and gravel mining from the active channels and floodplains are the most disastrous one as the activity threatens the very existence of the river ecosystem. The problem is acute in small rivers that have limited catchment area (<10,000 km2) and river sand and gravel resources. Lack of adequate information on the adverse impacts of river bed resource extraction is a major setback challenging regulatory systems for the wise-use and management of the rivers and its finite resources. This chapter deals with the historical perspectives, environmental issues and ecological significance of the small rivers of the world that are more responsive to uncontrolled sand and gravel extractions.