Sand Mining

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.

Rivers are the corridors connecting the terrestrial environment to the ocean realm. They play an important role in the sustenance of life systems of nature. As a geological agent, rivers carve out distinct suite of geomorphic features on the surface of the Earth. But human interventions consequent to economic developments in the past few decades have imposed tremendous pressure on rivers. As a result, most of the rivers in the world, especially the small rivers, have been altered to levels, often beyond their natural resilience capability. The present chapter gives a brief presentation of the river environment with special reference to its ecological and geological functions. River sediment characteristics, channel processes, classifications of rivers, and some of the classic concepts in riverine studies are also given in the chapter.

Large-scale sand extraction from river environment for building constructions is a global phenomenon. Indiscriminate sand mining imposes a series of physical, ecological, and socio-environmental impacts on the river basins. Furthermore, the extraction of this granular material is unavoidable as the sustainability of construction industry depends heavily on it. In rivers, construction grade sand occurs in different sources—active channels, floodplains, and river terraces. Different mining methods (mechanical or manual) are adopted for the extraction of sand from these sources under dry (above water table) and/or wet (below water table) conditions. This chapter describes briefly the different sources, methods and hydrogeological bearings of sand and gravel extraction processes in river ecosystems.

Mining of sand manifold higher than natural replenishments leads to severe damages to river systems. The mining process not only intercepts movement of sediments along the river channels, but disturbs the sediment balance established in the system over the geological time periods. Indiscriminate sand mining imposes several adverse impacts on the various environmental subcomponents of river ecosystems like bed forms, sediment milieu, water quality and quantity, flora and fauna, and socio-economic conditions of the people in the long run. The magnitude of these impacts depends on several factors such as type and scale of sand extraction, channel morphology, sediment transport processes and induced alterations in watershed characteristics. A better understanding of these impacts is very essential for formulating appropriate strategies for ameliorating and negating the impacts of river sand mining.

River sand mining is widespread in most of the developing and developed countries. Of the different types of fluvial systems, small rivers (catchment area <10,000 km²) are the worst affected due to indiscriminate sand mining than large rivers as the area available for dissipation of negative externalities is low in small river basins. This chapter deals with a brief account of the environmental effects of river sand mining reported from different parts of the world like Arizona, Italy, Kenya, Jamaica and Costa Rica, Malaysia, China, Sri Lanka, Nepal, Maldives and India.

Kerala state in the southwestern coast of India is blessed with 41 west flowing rivers that debouch into the Arabian Sea. These rivers are small with limited river bed resources. Among the various human interventions that are threatening rivers, indiscriminate river sand mining is of paramount importance as the activity irreparably degrades rivers and its adjoining aquatic environments. Studies reveal that the river bed in their storage zones is lowering at a rate of 5–20 cm per year. In the present chapter, two case studies have been examined to disclose the severity of environmental problems of sand mining from the rivers draining the Western Ghats—an ecologically sensitive area in the Peninsular India.

Depending on the geological and geomorphological setting, the magnitude of the environmental impacts of river sand mining also varies. The activity imposes marked environmental impacts on land, water, atmosphere, and socioeconomic conditions of a river basin. Environmental impact Assessment (EIA) is an important tool to assess the positive (beneficial) and negative (adverse) impacts of the sand mining. Two different methods—Matrix method and Rapid Impact Assessment Matrix method are used here to assess the environmental impact of sand mining in the longest river of Kerala—the Periyar river. The study reveals that the activity is a major threat to the very existence of the Periyar river in particular and the small rivers of tropics in general. The rivers are reported to be degraded considerably due to uncontrolled sand mining over the past few decades. The impact assessment reveals that the adverse environmental impacts of sand mining dominate over the marginal and short-term benefits.

The exponential rise in the demand for construction grade sand resulted from economic growth and the liberal development policies over the years have aggravated indiscriminate scooping of sand and gravel from river beds and floodplains of most rivers in the world. The situation warrants scientific interventions for judicious management of the river bed resources by striking a balance between its demand for development and the environmental concerns. The present chapter reviews the existing regulatory procedures, and also environmental laws/policies that are in practice in different parts of the world. A set of guidelines have been put forth to update the existing sand and gravel extraction policies in India and elsewhere for achieving the goal of sustainability in the case of sand resource extraction and managements.

Mining of sand and gravel with little regard to natural replenishment processes have imposed marked changes on the biophysical environment of the small rivers of Kerala in the southwest India. Considering the importance of management of river bed resources, the Government of Kerala enacted the legislation “The Kerala Protection of Riverbanks and Removal of Sand Act, 2001” to protect the rivers from large scale sand mining. This act also envisages provisions for periodic sand auditing in order to evaluate the sand mining process and to protect the rivers from unscientific human interventions. This chapter deals with the various procedures employed in sand auditing of the small rivers of Kerala (southwest India), taking the case of Periyar river an example.

Aggregate materials like sand, gravel, and crushed stone occupy a substantial volume of concrete used in constructions. The demand for high quality aggregates that meet the specifications of civil engineers for construction activities is increasing year after year. A better understanding of the aggregate properties is essential for ensuring the construction processes economical and civil structures long lasting. This chapter deals with a brief description of the characteristics and usefulness of fine aggregates for different construction purposes. The precautions that are to be taken during transportation and storage of aggregates are also discussed in the chapter.

Construction grade sand is in short supply in many parts of the world. This has resulted in growing demand of sand to maintain the pace of infrastructure development and construction industry. Therefore, there is an immediate need to bridge the gap between demand and supply of aggregates by encouraging the use of low cost, easily available alternatives to river sand. Also measures are to be taken to reduce the use of natural sand to the barest minimum by adopting technologies with lowland—no sand content in construction sector. This chapter gives an overview of the different sources of sand and the environmental problems linked to it during their extraction with special reference to Kerala state in southwest India.