Quantitative description of infiltration process is crucial for modeling soil water status as well as many other applications related to surface-subsurface hydrology. The importance of infiltration process has lead to develop several theoretical and empirical infiltration models. However, the applicability of these models is strongly subjected to soil spatial variability. In this study, the performance of Kostiakov, Mezencev, Horton and Philip infiltration models under different study sites were evaluated. For this purpose, the infiltration data of 123 sites with different soil series were obtained. The parameters of these models were then obtained, using sum of least squares error method. To quantify prediction accuracy of the models, the mean error (ME), root mean square error (RMSE), mean absolute of mean error (MAME) and Pearson correlation coefficient (r) were calculated. The results indicated that the performance of Kostiakov, Horton and Philip models were highly related to the location in which the data were collected. While the performance of Mezencev model was not site-dependent, the performances of all other models were varied with different soil textures. It was then concluded that Mezencev model can provide the best site-independent performance compares to Kostiakov and Philip models.

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In this study, the performance of rainwater harvesting (RWH) was assessed in terms of potential applicability for rainwater saving and non-potable water supply. Rainwater collecting from roofs of buildings was simulated in two cities with cold and semi-arid climate, namely Qazvin and Sanandaj.Rainfall statistics, information on the storage tank size, building roof areas and water demand (non-potable) were obtained. Buildings with roof areas of 100 m 2 to 300 m 2 were considered for the present study. It can be concluded that for cities located in cold and semi-arid climates, at least 60% of non-potable water can be supplied from roofs with a large area, a minimum 16% and maximum 70% for a low roof area, a minimum 8% and maximum 44% of the days per year from harvested rainwater. It is also found that for cities located in cold and semi-arid climates, it is possible to achieve at least 70% of non-potable water from large surface roofs. For the studied cities, with increasing tank size (1,000 to 5,000 L) rainwater saving was tangible for the same roof areas. Key words | cold and semi-arid climate, non-potable water, rainwater harvesting, roof area Palla et al. () examined the performance of domestic RWHs in different European climate zones. Their analysis demonstrated a strong correlation between the performance indexes and the antecedent dry weather period. Jing et al. () assessed the efficiency of RWHs formeeting non-potable water demands in four climatic conditions of China. They found that higher water supply reliability (time reliability) and water storage efficiency were possible for RWHs with a larger storage capacity for lower water demands, while a higher RWH efficiency was in relation to higher water demand, larger saving capacity

The behavior and treatment of a clay soil deposited in natural and saline (sodium chloride) water is studied through experimental tests. A clay soil was deposited in natural water and water with different concentrations of sodium chloride (40, 80 and 150 g/L) in a reservoir at lab. The samples were taken from dry deposited soil and they were treated with 5, 8 and 10% cement. Atterberg limits, compaction and unconfined compression tests were carried out on the deposited soil and treated soil samples. The results show that the physical and mechanical behaviors of soil deposited in natural water and salinity water are not the same and they are function of salt concentration. The results also indicate that cement can improve the strength of the deposited soil in saline water but this improvement is not a direct function of salt concentration. In addition, for a constant salt concentration the strength of treated soil is function of percent of cement and curing time.Based on SEM (Scanning Electron Microscopy) analysis, it was found that salt concentrations of 80 and 150 g/L may have prevented the interaction between soil and cement in the deposited soil.