NECESSITY FOR MODIFICATION OF MANAGEMENT PARAMETERS WHEN USING LOW-QUALITY WATER

The research assessed the necessity for modification of management var iables when treated wastewater (TW) is used for an existing border irr igation in lieu of normal water (NW). The infiltration parameters, cha racterized by Kostiakov equation, for normal water and treated wastewa ter were firstly obtained utilizing the double-cylinder infiltrometer. Secondly, the performance parameters considering the low quarter conc ept were computed through simulations for certain ranges of input data which included three roughness coefficients; three field slopes; thre e applied depths; and two field lengths. The zero inertia model was ut ilized to simulate flow along free outflow borders with longitudinal s lope. The infiltration rate and consequently its amount were found to decrease with application of treated wastewater. The declined infiltra tion led to a decrease in the application efficiency equal to nearly 1 5% as a contrast to an increase in the runoff ratio from 7% for normal water to 31% for treated water. Moreover, the low quarter depths were 150 and 125 mm for normal water and treated water, respectively, indi cating that there was less water stored in the field low quarter. It w as ultimately evident that the management parameters, application rate and time, need to be modified when treated wastewater is alternativel y used in lieu of normal water for which the system was supposedly des igned to obtain maximum efficiency. (C) 1998 Elsevier Science B.V.