y. zanganeh

Flood forecasting is considered through land use and building density in most urban designs, whereas this method has not been very successful based on the experiences. This study aimed to propose a proper method for flood forecasting in Sabzevar city, emphasizing the relationship between the parameters of hydrological models, urban development, and the scenarios considered in the comprehensive plan of 2005-2006 in Sabzevar city.

This research is applied and descriptive-analytical in terms of the aim and method, respectively. The data were collected using documentary and field methods. The flood susceptibility map of Sabzevar city was prepared using the SVM model. The model was validated using the ROC curve. The basin’s hydrology was studied using the Sabzevar Synoptic Meteorological Station data from 1358 to 1398. Urban hydrological models and Geographic Information System were used to predict the runoff during different urban development scenarios in the return periods of 2, 5, 10, and 25 years.

Due to the higher building density, the susceptibility to flooding risk vulnerabilities is higher in districts 1, 2, and 3 of Sabzevar city ROC showed the acceptable validity of the SVM model (AUC=0.9123). Surface runoff forecasts for the return periods and different scenarios indicate that the channels are not proper for runoff transmission.

It is very important to pay attention to the ratio of permeable and impermeable surfaces in comprehensive plans in order to prevent flooding. The SVM method is sufficiently compatible with Iranian conditions and can be used in similar conditions.

A dust storm is a phenomenon caused by particular conditions such as harsh wind, dry air and bare soil that is prone to erosion. The Sistan region in the southeast of Iran is one of the most affected areas by dust storms. This study was conducted to analyze the relationship between dust and rural population changes in the Sistan region (including 5 cities: Zabol, Helmand, Zahak, Nimroz and Hamoon) over the past 25 years (1991-2016).

This is a descriptive-analytical study and the required data are collected through desk studies using demographic statistics and satellite images. The collected data were analyzed using descriptive and inferential statistical analyzes including correlation coefficient tests.

The results of comparing the rate of rural population growth in the studied area in Sistan and Baluchestan province showed that in all 4 time periods (1991- 1996, 1996-2006, 2006-2011, and 2011-2016) the annual rate of rural population growth in the studied area had been significantly less than the annual rate of the provincechr('39')s rural population growth. Furthermore, the results of the study showed that there is a significant negative relationship between the average number of dusty days in the region in all four studied periods and the average annual rate of rural population growth in rural areas.

according to the findings of the current study, it can be concluded that the villageschr('39') potential to keep the population is highly dependent on natural conditions, especially sand and dust storms as a result of successive droughts in this region.