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Herzig M.A.,University of Queensland | Herzig M.A.,Cooperative Research Center for Irrigation Futures | Barnes G.T.,University of Queensland | Gentle I.R.,University of Queensland
Journal of Colloid and Interface Science | Year: 2011

To be suitable for reducing water evaporation, monolayers need to be easy to apply and also spread quickly across the surface of water. However, the choice of monolayer often involves a compromise between spreading rate and evaporation resistance. Because emulsions of the monolayer material have been suggested as a way to improve spreading, emulsions were made with the long-chain alcohols hexadecanol, octadecanol and eicosanol using the non-ionic surfactants Brij 78 and Tween 60 as emulsifying agents. The emulsions of octadecanol and eicosanol spread faster than the corresponding powder. However there was no improvement in the spreading of hexadecanol emulsion due to a significant amount of the material dispersing into the bulk water instead of spreading at the interface. The choice of emulsifier to stabilise the emulsions is critical for effective evaporation resistance. Whereas the octadecanol emulsion made with Brij 78 showed improved evaporation resistance, the emulsion with Tween 60 had an appreciably lower evaporation resistance than powdered octadecanol. One limitation of the emulsion application method is the poor spreading on surfaces with an already high surface pressure. © 2011 Elsevier Inc.

Sikandar P.,University of Agriculture at Faisalabad | Sikandar P.,CSIRO | Bakhsh A.,University of Agriculture at Faisalabad | Arshad M.,University of Agriculture at Faisalabad | Rana T.,Cooperative Research Center for Irrigation Futures
Environmental Earth Sciences | Year: 2010

A geoelectrical resistivity survey using vertical electrical sounding (VES) was conducted at Chaj Doab (land between rivers Jhelum and Chenab, Pakistan) and Rachna Doab (land between rivers Chenab and Ravi, Pakistan), with the objective of investigating groundwater conditions. A total of 90 sites were selected with 43 sites in Chaj and 47 sites in Rachna Doabs. The resistivity meter (ABEM Terrameter SAS 4000, Sweden) was used to collect the VES data by employing a Schlumberger electrode configuration, with half current electrode spacings (AB/2) ranging from 2 to 180 m and the potential electrode (MN) from 1 to 40 m. The field data were interpreted using the Interpex IX1D computer software and the resistivity versus depth models for each location was estimated. The outputs of subsurface layers with resistivities and thickness presented in contour maps and 3-D views by using SURFER software were created. A total of 102 groundwater samples from nearby hydrowells at different depths were collected to develop a correlation between the aquifer resistivity of VES and the electrical conductivity (EC) of the groundwater and to confirm the resulted geophysical resistivity models. From the correlation developed, it was observed that the groundwater salinity in the aquifer may be considered low and so safe for irrigation if resistivity >45 Ω m, and marginally fit for irrigation having resistivity between 25 and 45 Ω m. The study area has resistivities from 3.9 to 2,222 Ω m at the top of the unsaturated layer, between 1.21 and 171 Ω m, in the shallow aquifers, and 0.14-152 Ω m in the deep aquifers of the study area. The results indicate that the quality of groundwater is better near the rivers and in the shallow layers compared to the deep layers. © 2009 Springer-Verlag.

Chen Y.,CSIRO | Chen Y.,Cooperative Research Center for Irrigation Futures | Yu J.,CSIRO | Yu J.,Shanghai Normal University | And 2 more authors.
Environmental Modelling and Software | Year: 2010

With growing interest in extending GIS to support multi-criteria decision-making (MCDM) methods, enhancing GIS-based MCDM with sensitivity analysis (SA) procedures is crucial to understand the model behavior and its limitations. This paper presents a novel approach of examining multi-criteria weight sensitivity of a GIS-based MCDM model. It explores the dependency of model output on the weights of input parameters, identifying criteria that are especially sensitive to weight changes and to show the impacts of changing criteria weights on the model outcomes in spatial dimension. A methodology was developed to perform simulations where the weights associated with all criteria used for suitability modelling were varied one-at-a-time (OAT) to investigate their relative impacts on the final evaluation results. A tool which incorporates the OAT method with the Analytical Hierarchy Process (AHP) within the ArcGIS environment was implemented. It permits a range of user defined simulations to be performed to quantitatively evaluate model dynamic changes, measures the stability of results with respect to the variation of different parameter weights, and displays spatial change dynamics. A case study of irrigated cropland suitability assessment addressing the application of the new GIS-based AHP-SA tool is described. It demonstrates that the tool is spatial, simple and flexible. © 2010.

Reading L.P.,University of Queensland | Reading L.P.,Cooperative Research Center for Irrigation Futures | Reading L.P.,Khan Research Laboratories | Baumgartl T.,University of Queensland | And 2 more authors.
Soil Science | Year: 2012

Amelioration of sodic soils is commonly achieved by applying gypsum, which increases soil hydraulic conductivity by altering soil chemistry. The magnitude of hydraulic conductivity increases expected in response to gypsum applications depends on soil properties including clay content, clay mineralogy, and bulk density.The soil analyzed in this study was a kaolinite rich sodic clay soil from an irrigated area of the Lower Burdekin coastal floodplain in tropical North Queensland, Australia. The impact of gypsum amelioration was investigated by continuously leaching soil columns with a saturated gypsum solution, until the hydraulic conductivity and leachate chemistry stabilized. Extended leaching enabled the full impacts of electrolyte effects and cation exchange to be determined.For the columns packed to 1.4 g/cm, exchangeable sodium concentrations were reduced from 5.0 ± 0.5 mEq/100 g to 0.41 ± 0.06 mEq/100 g, exchangeable magnesium concentrations were reduced from 13.9 ± 0.3 mEq/100 g to 4.3 ± 2.12 mEq/100 g, and hydraulic conductivity increased to 0.15 ± 0.04 cm/d. For the columns packed to 1.3 g/cm, exchangeable sodium concentrations were reduced from 5.0 ± 0.5 mEq/100 g to 0.51 ± 0.03 mEq/100 g, exchangeable magnesium concentrations were reduced from 13.9 ± 0.3 mEq/100 g to 0.55 ± 0.36 mEq/100 g, and hydraulic conductivity increased to 0.96 ± 0.53 cm/d.The results of this study highlight that both sodium and magnesium need to be taken into account when determining the suitability of water quality for irrigation of sodic soils and that soil bulk density plays a major role in controlling the extent of reclamation that can be achieved using gypsum applications. Copyright © 2012 by Lippincott Williams & Wilkins.

Abbas A.,Cooperative Research Center for Irrigation Futures | Hanjra M.A.,Charles Sturt University | Akbar S.,Industry and Investment NSW
Physics and Chemistry of the Earth | Year: 2013

Managing salinity in irrigated agriculture is crucial for minimising its negative environmental impacts and for ensuring the long-term sustainability of irrigated agriculture. It demands establishing rapid monitoring systems that help develop sustainable management plans. Remote sensing offers several advantages over the conventional proximal methods to map and predict areas at salinity risk. This paper presents an integrated approach to characterize soil salinity using remotely-sensed data in the District Faisalabad, Punjab, Pakistan. The IRS-1B LISS-II digital data was acquired and analysed in combination with field data and topographical maps. Remotely-sensed data based salinity indices or band combinations were developed to monitor the occurrence pattern of salt-affected soils. Using supervised maximum likelihood classification, the images were classified into eight land use classes with an overall accuracy of around 90%. The classified images showed that 22.2% of the total area was under salt-affected soils in 1992. The occurrence pattern of salt-affected soils varied with positive and negative trends during 1992-1995 to a minimum of 10.6%. The delineation analysis into levels of saline soils revealed three types based on USDA classification (USDA, 1954). The slightly saline, moderately saline and strongly saline soils during 1992 were in the order of 15%, 3%, and 1% respectively. The interactive behaviour of salinity and sodicity and their combinations showed that saline-sodic soils occurred predominantly ranging from 6.9% to 17.3% of the salt-affected soils. The shallow watertable was found to be of hazardous quality in 28% of the study area. The relationship between salt-affected soils, waterlogged soils and groundwater quality revealed that 60-70% of the salt-affected soils occurred in shallow watertable areas during 1992-1995. The reuse of poor quality groundwater for irrigation and the failure of tile drainage system in the area are likely to further increase the risk of salinisation in the Indus Basin of Pakistan. © 2010 Elsevier Ltd.

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