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[1] Reference crop evapotranspiration (ET o ) estimation is of importance in irrigation water management for the calculation of crop water requirements and its scheduling, in rainfallrunoff modeling and in numerous other water resources studies. Due to its importance, several direct and indirect methods have been employed to determine the reference crop evapotranspiration but success has been limited because the direct measurement methods lack in precision and accuracy due to scale issues and other problems, while some of the more accurate indirect methods, e.g., the Penman-Monteith benchmark model, are timeconsuming and require weather input data that are not routinely monitored. This paper has used the Kohonen self-organizing map (KSOM), unsupervised artificial neural networks, to predict the ET o. based on observed daily weather data at two climatically diverse basins: a small experimental catchment in temperate Edinburgh, UK and a semiarid lake basin in Udaipur, India. This was achieved by using the powerful clustering capability of the KSOM to analyze the multidimensional data array comprising the estimated ET o (based on the Food and Agricultural Organization (FAO) Penman-Monteith model) and different subsets of climatic variables known to affect it. The findings indicate that the KSOM-based ET o estimates even with fewer input variables were in good agreement with those obtained using the conventional FAO Penman-Monteith formulation employing the full complement of weather data at the two locations. More crucially, the KSOM-based estimates were also found to be significantly superior to those estimated using currently recommended empirical ET o methods for data scarce situations such as those in developing countries.

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Abstract. This literature review was conducted on the physical and rheological properties of animal manure slurries and their applications. The review revealed the importance of these properties in the design of anaerobic treatment plants, pipe systems to transport slurries to treatment and storage units, and other applications and management of raw and treated slurries. The selection of pumping and mixing equipment and their power requirements, the flow behavior, mass, and heat transfer, the quality of mixing, pressure head loss, and other applications of manure slurries are affected by the physical and rheological properties. The review shows that manure slurries generally exhibit non-Newtonian pseudoplastic fluid behavior with a decreasing apparent viscosity as the shear rate increases and that the power law equation can successfully be used to describe the relationship between shear stress and shear rate, especially for low total solids concentrations. Keywords: Animal manure slurries, Apparent viscosity, Non-Newtonian pseudoplastic fluids, Power law equation, Rheological properties.