Field-scale assessment of deep drainage risk.

Book Title: NA
Year Published: 2002
Month Published: NA
Author: Triantafilis, J. ; Huckel, A. I. ; Odeh, I. O. A.
Book Group Author: NA

Improving irrigation efficiency is of primary importance in arid and semi-arid regions of the world as a consequence of increasing incidences of soil and water salinisation. In the cotton-growing regions of Australia salinisation is generally a result of inefficient irrigation practices, which lead to excessive deep drainage (DD). There is therefore the need to apply a relatively inexpensive approach to assessing where inefficiencies occur and make prediction of suitability of existing and new water storage sites. However, physical methods of measuring DD, such as flux meters and lysimeters, are time-consuming and site-specific. In this paper we apply a rapid method for determining the spatial distribution of soil in an irrigated cotton field in the lower Gwydir valley. First, ECa data (using EM38 and EM31) were used to determine a soil-sampling scheme for determining soil information such as clay content and exchangeable cations to a depth of 1.2 m. The soil data and water quality information were input into the SaLF (salt and leaching fraction) model to estimate DD rate (mm/year). In developing the relationship between ECa and estimated DD, three exponential models (two-, three- and four-parameter) were compared and evaluated using the Aikakie information criteria (AIC). The three-parameter exponential model was found to be best and was used for further analysis. Using the geostatistical approach of multiple indicator kriging (MIK), maps of conditional probability of DD exceeding a critical cut-off value (i.e. 50, 75, 100 mm) were produced for various rates of irrigation (I=300, 600, 1©200 and 1 500 mm/year). The areas of highest risk were consistent with where water-use efficiency was problematic and thus leading to the creation of perched water tables. The advantage of this approach is that it is quick and is applicable to situations where efficient use of water is required. The results can be used for irrigation planning, particularly in the location of large irrigation infrastructure such as water reservoirs.

Pages: 183 - 192
Volume: 21
Number: 4
Journal: Irrigation Science
Journal ISO: NA
Organization: NA
Publisher: NA
ISSN: 0342-7188

clay fraction, cotton, drainage, electrical conductivity,exchangeable cations, irrigated farming, irrigation water, leaching,risk assessment, salinization, salts, spatial distribution, waterquality, water use efficiency, Australia, New South Wales, Gossypium,Malvaceae, Malvales, dicotyledons, angiosperms, Spermatophyta, plants,eukaryotes, Australasia, Oceania, Developed Countries, Commonwealth ofNations, OECD Countries, Australia, water composition and quality, FieldCrops (FF005) (New March 2000), Soil Chemistry and Mineralogy (JJ200),Soil Physics (JJ300), Soil Water Management (Irrigation and Drainage)(JJ800) (Revised June 2002) [formerly Soil Water Management]

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