مهندسی آبیاری و آب ایران
سال:1390 | دوره:1 | شماره:4 |تعداد مقالات:7

In hydrology, although we can not determine the time of flood occurrence, however, by analyzing previous events we can find out the probability of their average occurrences which will be the base for future environmental management programs such as flood control and river marginal planning. In this study several statistical distributions were applied to fit on 7 watershed peak flows at Bohshar province using Analytical Hierarchy (AHP) Process and SMADA software. AHP method and group decision making were used to select the best distribution model. The results indicated 3 parameters lognormal distribution was the best model for 5 watershed including Sarcanat, Jarebala, Sadabad, Ghantareh and Boshigan. The Gumbel and normal distribution was the best model for the watersheds of Kolal and Baghan, respectively. Also, the difference between observed and estimated peak values were lower for the low return periods (<50 years) and the highest differences were for the upper return periods (>50 years).

Kerman province due to special geographic features such as cross the desert and mountainous conditions has specific weather and climate variation and particularly good conditions for cultivation of crops and the garden. Considering the limited threshold of tolerance of plants to meteorological parameters, any abnormalities in these parameters including the occurrence of stress freezing and thaw cycles will be damage to agricultural production. In this research for locating freezing and thaw cycles in the Kerman province, the data of daily minimum and maximum temperatures of 9 synoptic stations was used over 20 statistic years (1989-2008). Also 4 distinct range of temperatures including: the minimum temperatures lesser and equal whit -2 and the maximum temperatures greater and equal whit 2 (A), the minimum temperatures lesser and equal whit -3 and the maximum temperatures greater and equal whit 3 (B), the minimum temperatures lesser and equal whit -4 and the maximum temperatures greater and equal whit 4 (C), the minimum temperatures lesser and equal whit -5 and the maximum temperatures greater and equal whit 5 (D), were presented. After data processing by a computer program into the FORTRAN space, the number of days with this phenomenon for each station was determined as monthly, seasonal and annual, also monthly and seasonal relative frequency are calculated and compared these values with the critical temperature of crops and garden plants, was identified risky areas on province. The investigation of annual graphs showed that Anar station has most days of freezing and thawing cycles during the year. Review of seasonal relative frequency offreezing and thaw cycles show that winter has the most abundance of this phenomenon than other seasons, and two city of Bam and Baft shows higher rate of freezing and thaw in this season. But despite of this topic, because of cold acclimation phenomenon, cold-season cereals and fruit trees have less damage than spring and autumn seasons. Review of monthly results also showed that early planting (in April) fruit trees and crops such as wheat, barley, millet and cotton in the cities including Shahrebabak, Kerman, Kahnuj and Sirjan is risky, while in the cities of Baft, Bam and Jiroft, this plant will not face with damage. Also, since the abundance of this phenomenon in regions such as Shahrebababak, Sirjan and is better be accomplished autumn cultivation (in November and December) of this plants by using of resistant cultivars.