JWSS - Journal of Water and Soil Science

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An intense storm occurred on June 6, 1992 in Mashhad city and its suburb, which caused a flood in the residential areas of Najafi, Chahar-cheshmeh and Nodareh. As a consequence of the abnormally huge flood, 25 people lost their lives and many structures were destroyed. Three recording rain gages located in Mashhad city (airport, College of Agriculture, and Water Authority) and one in the suburbs (Toroq dam) recorded the temporal distribution of the storm. Twenty five other nearby rain gages in the region also recorded the event. The rainfall hyetographs and rainfall amounts were analyzed. The results of this survey showed that: a) maximum rainfall intensity over a 15-minute duration in the College of Agriculture station, one of the centers of the storm, was 112 mm/hr, b) temporal distribution of rainfall for all recording stations were nearly the same, c) these patterns were in close agreement with all historic storms, and d) a return period of 380 years was implied via comparing the maximum rainfall intensity with relevant IDF curves. As a consequence, although an intense storm had happened, it was simply an outlier.

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In order to determine the water production functions for winter wheat (Variety, C73,5), an experiment was conducted in through of a complete randomized block design with 9 treatments and 3 replications in Mashhad region. While the first treatment (as a control treatment) was selected on the basis of irrigation in all growth stages of growing season, six treatments were selected on the basis of an irrigation cut in the six stages of growth season and two remaining treatments were also selected on the basis of a constant reduction of irrigation to the amount of 20 and 60 percent. In general the water stress was caused that the amounts of depth percolation were calculated negatively which was an indication of the water uptake from below the root zone. According to results, models of the yield in per unit of area had a higher correlation coefficient of determination in relation to the models of the yield in per unit of water. The derived sensitivity coefficients indicated that the winter grain formation and flowering stages were respectively the most sensitive stages of the growth season stages to the water deficit. There are some differences between these computed sensitivity coefficients and the amounts reported by the other researchers. Probably the variety, degree of stress, the climatic conditions and some unknown factors may explain these differences.

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In this research, to locate and prioritize suitable areas for flood spreading in Mashhad plain, 10 criteria were used including land use, slope, alluvium thickness, distance to well, distance to subterranean, distance from the village, water table drawdown, permeability coefficient, electrical conductivity, and drainage density. Weighting process was done by Analytic Network Process (ANP) and fuzzy logic. After preparing and weighting the maps of all appropriate measures for locating suitable areas of flood spreading maps based on fuzzy logic and analytic network process model, the final map was prepared for prioritizing suitable areas for flood spreading. Then by applying the limiting layer that is a combination of three criteria of land use, slope and geomorphology, the final map of suitable areas for flood spreading was prepared and prioritized. The results showed that among the 10 factors influencing flood spreading, the thickness of alluvium criteria by weight of 0.27 was identified as the most effective layer in suitable areas for flood spreading. Most of the suitable regions located in slope less than 3% that represents its considerable impact in implementation of flood spreading. Mashhad plain potential for flood spreading, after removing exception areas (40.8% of total area), were defined in four inappropriate, relatively appropriate, appropriate and perfectly appropriate classes, that include 2.7, 25.9, 26.5 and 1.5% of the plain area, respectively.