مجله مخاطرات محیط طبیعی
پیاپی 22 (زمستان 1398)

Geographically, the studied region in Ilam dam watershed is between 46°16'36'' to 46°38'32'' eastern longitude and 33°23'27'' to 33°38'54'' northern latitude. The area of case study is476.5 km2 with the highest and lowest height as 2400 m and 640 m above sea level. In this study, in order to map the landslide hazard zonation of Ilam Cham Gordalan dam basin by weighting the main criteria and using fuzzy membership functions in Arc GIS and establishing the best relationship functions between the presence and absence of landslides, a set of parameters is used. Then, each of the factors affecting landslides in the under-study area such as slope, slope direction, elevation, geology, land use, distance from roads, distance from drainage network, distance from the fault, and rainfall map has been digitized in the software environment of ArcGIS and are used in the fuzzy analysis. Landslide hazard in the under-study area has been zoned using fuzzy operators (Gamma, Product, Sum, Or, And). After the fuzzy fiction phase, the effective measures in the landslide occurrences in the area have been prepared using the above-mentioned method through Gamma fuzzy operators with Lambda 0.2،0.5، 0.8and 0.9 and by comparing final maps, the ideal model for the landslide hazard zonation in the area has been selected. The results show that among the above-mentioned operators, the Gamma operator with Lambda 0.9 is considered to be the most appropriate method for zoning the landslides in this area due to its fine fuzzy fiction of each criterion based on the distribution maps of occurred landslides and the way of separating risk classes.

Occurrence of factors such as decreasing atmospheric precipitation, population growth and industry progress has increased the importance of paying attention to the proper quality management of water resources. Pollution sources are categorized in different aspects. In this research, controllable and uncontrollable pollutant management is considered. To manage and control the damages caused by each of these types of pollutants, a certain qualitative tool is employed. Assimilation capacity is suggested when the pollution source is controllable and dilution flow is the proposed tool of this investigation to uncontrollable pollution management. To analyze and calculate the above mentioned qualitative tools, the simulation process is used by analytical solution of the advection-diffusion equation. The case study considered in this research is an area with specific characteristics, which has been investigated by many previous researches. Efficient indices in determination of qualitative tools including mean area of unallowable concentration (¯(c_a)), affected distance (X) and duration of unallowable pollution concentration contact with river (T) were calculated in each simulation process loop. The results demonstrated that 94.1% variation of river-reservoir flow discharge can change the assimilation capacity up to 99.3%. Moreover, by applying a suitable dilution flow, 10 and 20 tons of sudden contaminants arrived at the permitted concentrations of 0.5 and 1 mg / l over the river. In this process, values of the crucial quality parameters of the river ((c_a) ، X و T) change up to 96.6%, 92.2% and 53.7%, respectively.

The progress in flood estimation techniques has enabled us to use rainfall-runoff models to evaluate the hydrographic properties of the flood in watersheds, thus lowering the risks of flooding. Accordingly, this study aimed to determine the peak flood discharge for Amuqin to reveal the impact of land use changes on peak flood discharge using a WMS model. Amuqin area stretches across approximately 78 km2 of land. The Curve Number (CN) of the basin was found by integrating land use maps with soil hydrologic group (B, C, D) obtained from analyzing Landsat 8 Images in IDRISI32 and overlaying the maps in ArcGIS and were estimated at 76.4 and 78.7 for 2000 and 2015, respectively. The model calibration (RE= 7.17، RMSE = 0.44) and validation results (RE%= 2.51, RMSE= 0.0042) with rainfall-runoff phenomena in the area, suggested consistency with observations. Given the high sensitivity of this method to rainfall distribution, an analysis of rainfall across the region is required to obtain reliable results. Further, the curve number of the basin showed a 3% increase between 2000 and 2015 due to the reduced quality of the rangelands and the change to agricultural land use in areas of the basin most prone to flooding and erosion, which increases the peak flood discharge by 22, 26 and 25.5% for return periods of 25,50 and 100 years, respectively. The management of land use seems in order to prevent future increases in the catchment CN.

Since the mid-20th century, alluvial plains in the south of Rey township, due to the vicinity to Tehran city and roads, has favored the establishment of giant plants such as Tehran oil refinery and its auxiliary that air and land pollutions are inevitably part of such industries. This study is provided to investigate the sources and spatial spreading of a contaminant in the air, soils, and plants of Baghershar town. The studied town locates in 4 km from Tehran and has an area of 551.5 hectares. The data obtained from the measurements had been done by Baghershahr municipality in 2016. Resource data were arranged within a GIS framework and it is used interpolation methods to produce zoning maps. Findings show that in half of the time, the concentration of particles in the air, exceeds the standard limit, and for soils, the average amount of 15362 mg/kg of TPHs indicate high contamination. Combined zoning maps showed that southeast of the city was more polluted. This zoning map is highly consistent with the zoning of pollutants in the soil and is more or less consistent with the zoning in plants, but does not conform to zoning map of air pollutants. Plants and industrial complexes, loading, and transferring fuels, and transportation were a source of atmospheric pollution. Penetration of contaminants into soils and plants is often from non-atmospheric origins, but passing the wastewater channel alongside the town, and green spaces irrigation with polluted water extracted from wells, affecting contaminants spreading.

Considering the vital importance of the ozone layer and the rising course of increasing its destructive factors in recent decades, the necessity of studying the ozone layer in order to know its state in the atmosphere of Iran has become more recent. In recent years, several techniques and techniques have been used to monitor this vital gas in the atmosphere of the planet. Meanwhile, the use of satellite data has become widespread because of the availability and availability of features such as spatial, temporal and spatial resolution. The study also uses ozone data collected by the AIRS based on the AQUA satellite, which provides an opportunity to study the process of Ozone changes in the atmosphere of all parts of the world, including Iran. The relevant data were extracted from the https://disc.gsfc.nasa.gov/datasets/AIRS3STM_006 website with the NetCDF format, with one-day and one-day temporal resolution and a 1° x 1° spatial resolution during the 15-year statistical period (2003 - 217) ArcGIS and Grads software was analyzed, visualized, analyzed. The results indicate that annual ozone has dropped in the atmosphere of Iran. Among the seasons, the highest and lowest ozone levels occurred in the spring and autumn seasons, and the highest and lowest monthly ozone levels were observed in March and October, respectively. In terms of location, moving from the south to the north, it is approximately uniformly increased by the amount of ozone, so that the maximum total ozone (TOC) in Pars Abad plain (318 Dobson) and its lowest value in an interconnected area Provinces of Hormozgan, Kerman and Fars, and part of Southeastern Iran (283 Dobson). The maximum ozone concentration (ozonosphere) is also evident at an altitude of 27-40 km.