ASCE Manual of Practice No. 70

MOP 70 is a comprehensive reference to estimating the water quantities needed for irrigation of crops projects based upon the physics of evaporation and evapotranspiration (ET).

Sponsored by the Committee on Evapotranspiration in Irrigation and Hydrology of the Irrigation and Drainage Council of the Environmental and Water Resources Institute of ASCE

Evaporation, Evapotranspiration, and Irrigation Requirements is a comprehensive reference to estimating the water quantities needed for irrigation of crops based upon the physics of evaporation and evapotranspiration (ET). This new edition of MOP 70, which updates and expands the 1990 original, provides improved and standardized methods to estimate evaporation and ET and to apply and evaluate calculations. The methods, which have both a physical and practical basis, improve clarity, accuracy, and consistency for systems design and management. They are also useful in legal applications involving water agreements, water disputes, and water rights.

As competition for water increases and water resources are depleted, this book provides the critical tools to accurately quantify amounts of water consumed by irrigated agriculture. The first part covers basic concepts and physical principles, such as evaporation and ET processes, soil-water-plant systems, energy balance, surface energy-air mass interactions, and evaporation from water surfaces. The second part on ET from land surfaces explains components of measurement and details on estimation; reference crop ET; evaporation from soil; the crop coefficient method; the Penman-Monteith and energy-balance equations; and regional estimates. A third part discusses estimation of irrigation water requirements (IWR) and streamflow depletions. Thirteen appendixes provide tables of mean and basal crop coefficients and background information on concepts and equations used throughout the manual.

MOP 70 is intended for use by consulting engineers and scientists working on water issues and by instructors of agricultural and civil engineering, hydrology, and environmental and agricultural sciences.