|Ayars, James - Jim|
Submitted to: Proceedings of the USCID Wetlands Seminar
Publication Type: Proceedings
Publication Acceptance Date: 2/10/2002
Publication Date: 10/23/2002
Citation: Ayars, J.E., Christen, E.W. 2002. Best management practices for subsurface drainage and system design and management for irrigated agriculture. Proceedings of the USCID Wetlands Seminar. No Vol., pg. 187-196. Interpretive Summary: The total maximum daily load (TMDL) of many pollutants is being quantified for water being discharged into surface water supplies in an effort to clean up the nations water resources. Agriculture is a contributor of sediment, nitrate, and pesticides in surface water return flows that are being discharged to rivers and streams. However, some of the water being discharged to surface comes from subsurface drainage systems. These waters often contain toxic trace elements as well as nitrate and salt. Best management practices (BMP's) have been developed for irrigated agriculture to control erosion from surface irrigation, and nitrate losses to ground water. However, no BMP's have been developed to minimize the flow of drainage water and help reduce the load of pollutants attributable to subsurface drainage. This paper describes the development of BMP's for the design and management of subsurface drainage systems. Implementation of these BMP's will result in reduced drainage flow and contribute to reaching the TMDL goals for rivers and streams receiving subsurface drainage water.
Technical Abstract: Drainage water disposal is the one of the most vexing problems facing irrigated agriculture in arid and semi-arid areas of the world. This effluent may carry salt, toxic elements, pesticides, and fertilizers and thus represent a pollution source that contaminates the receiving water body. The use of TMDL's is an attempt to control pollution and minimize the impact of drainage on water quality. Best management practices (BMP's) have been developed for irrigated agriculture to address problems related to nitrate losses in irrigation, and erosion losses from irrigated areas. Prior to this time there were no BMP's developed for managing drainage effluent in irrigated agriculture. Drainage effluent was not considered a resource to be managed only a waste product to be discharged and little thought was given to managing a drainage system to increase crop water use from shallow ground water. No thought was given to managing irrigation and drainage systems as an integrated water management system. It is no longer acceptable to design and manage irrigation and drainage systems without regard to the environmental consequences. This paper presents BMP's that were developed for designing and managing subsurface drainage systems used in arid and semi-arid irrigated areas.