Gravel Mining in Rivers
In many areas, sand and gravel are mined from alluvial deposits (active channels and floodplains) to provide construction aggregate, for purposes such as concrete, asphalt, road base and sub-base, and drain rock.  Active channel deposits are often of suitable quality to be used in Portland Cement (PCC-grade) because the gravels are well-sorted, with unstable fragments having been  eliminated by abrasion in river transport.  Moreover, river deposits are often located near markets for the product, minimizing transport costs, which are the largest costs in the industry.  The scale of aggregate extraction is commonly not recognized.  In California, over 100 million tonnes are produced annually, virtually all from alluvial deposits, about ten times the amount of sand and gravel that is probably produced by erosion of the landscape.

Mining in active river channels typically results in incision upstream of the mine (by knickpoint migration) and downstream (by sediment starvation).  Incision may cause undermining of structures, lowering of alluvial water tables, channel destabilization and widening, and loss of aquatic and riparian habitat.  Floodplain gravel pits have the potential to become good wildlife habitat upon reclamation, provided that margins are appropriately contoured and water table fluctuations are not excessive.  During floods, the river channel may come to occupy a course through floodplain gravel pits, resulting in pit capture and the transformation of floodplain pits to in-channel pits.
 

SELECTED RELEVANT PUBLICATIONS

Kondolf, G.M., M. Smeltzer, and L. Kimball. 2001. Freshwater gravel mining and dredging issues.  White paper prepared for the Washington Departments of Fish and Wildlife, Ecology, and Transportation, Olympia. Report No. CEDR-R01-02, University of California, Berkeley. Available at: http://www.wdfw.wa.gov/hab/ahg/freshdrg.pdf

Kondolf, G.M. 1998. Environmental effects of aggregate extraction from river channels and floodplains. In P. Bobrowsky (ed.) Aggregate Resources: A Global Perspective (pp. 113-129). Balkema, Rotterdam.

Kondolf, G.M. 1998. Large-scale extraction of alluvial deposits from rivers in California: Geomorphic effects and regulatory strategies. In P. Klingeman et al. (eds.) Gravel-Bed Rivers in the Environment (Proceedings of the Fourth International Workshop on Gravel Bed Rivers) (pp. 455-470). Water Resources Publications, Highlands Ranch, Colorado.

Kondolf, G.M. 1997. Hungry water: Effects of dams and gravel mining on river channels. Environmental Management 21(4):533-551.

Kondolf, G.M., J.C. Vick, and T. Ramirez. 1996. Salmonid spawning habitat restoration in the San Joaquin River basin, California: An evaluation of project planning and success. Report No. 90, Centers for Water and Wildland Resources, University of California, Davis, June 1996.

Kondolf, G.M. 1995. Managing bedload sediments in regulated rivers: Examples from California, USA. Geophysical Monograph 89:165-176.

Kondolf, G.M. 1994. Environmental planning in the regulation and management of instream gravel mining in California. Landscape and Urban Planning 29:185-199.

Kondolf, G.M. 1994. Geomorphic and environmental effects of instream gravel mining. Landscape and Urban Planning 28:225-243.

Klein, R., and G.M. Kondolf. 1994. Lower Eel and Van Duzen Rivers: Description of necessary components for development and implementation of river management plan. Report to the County of Humboldt, Planning Department, Eureka, California.

Kondolf, G.M. 1994. Reclamation and instream gravel mining in California. In Western Wetlands: Selected Proceedings of the 1993 Conference of the Society of Wetland Scientists, Western Chapter (pp.136-142). Davis, California.

The California State Lands Commission. 1993. California's rivers: A status and trends report on public trust resources. California State Lands Commission, Sacramento. (Contributed text on channel geomorphology, hydrology, and impacts of dams, instream gravel mining, etc.)

Kondolf, G.M. 1993. The reclamation concept in regulation of gravel mining in California. Journal of Environmental Planning and Management 36:397-409.

Kondolf, G.M., and M.L. Swanson. 1993. Channel adjustments to reservoir construction and instream gravel mining, Stony Creek, California. Environmental Geology and Water Science 21:256-269.
Alameda Creek, Freemont, California, flanked by former gravel pits 
now used to recharge groundwater.  (photo by Kondolf)


In-channel gravel mining, Ningo, China  (Photo by Kondolf 1997)