آسیب‌پذیری سکونتگاه‌های روستایی از ماسه ‌های روان بستر خشک تالاب بین‌المللی هامون در شهرستان هیرمند

Every year, natural hazards happen severely around the world. Iran is included in the first 10 countries in the world susceptible to natural hazards, and has experienced 30 hazards out of total 35 hitherto. In this connection, moving sands, as a natural hazard, creates changes to ecological conditions which cause a rupture in the lives of people. The aforementioned hazards leave adverse effects on human habitations and impose wide environmental and socio-economic damages upon societies. Moreover, the sand mass covers arable lands and residential areas, generates air pollution, brings in destruction of topsoil, harms animals, and brings about many losses. This eases desertification and causes damages. Therefore, taking areas subject to moving sand into consideration is very significant in rural planning. Hirmand township in north of Sistan and Balouchestan province is an area open to moving sand onrush. Unfortunately, due to Sistan drought and Hamoon international wetland dryness as a result of the dominant120-day winds in the area, moving sands have come to affect rural settlements. This has put the villagers of Hirmand township to so much trouble. Hence, an investigation and analysis of rural settlements vulnerability to moving sand damages in the villages of Hirmand township is of great significance as a step toward better control of the problem.       The present study is a descriptive-analytic survey containing documentary sources, field studies, as well as village and household questionnaires.  The statistical population consists 303 villages in Hirmand township, from which a total of 56 were selected as the sample of the study based on advice given by experts at Housing Foundation of Islamic Revolution, rural administrators and local council members. Analytic hierarchy process (AHP), statistical analyses, spatial analyses, and the software Expert Choice, SPSS, and ArcGIS were used in data analysis. This study, hence, attempts to identify vulnerable habitations and categorize them by employing 54 indexes and assessing and putting them together in different levels.       According to the findings of this study, from the total villages subject to moving sand problem, 55.35 % are found with low or very low vulnerability and 30.38 % are placed in high or very high vulnerability ranges. The investigation of distribution of the villages under study given the vulnerability intensity to moving sand storm revealed that the villages of low or very low vulnerability are situated in the central and western parts of the area under study. These villages enjoy low vulnerability due to water resources, Tamarix hispida trees planted by state-run entities in the moving sand paths, and being away from dry bed of Hamoun Wetlands. On the other hand, the villages of high and very high vulnerability are placed mostly in the northern part of the area under study and adjacent to Hamoun Wetlands.    There are several factors playing key roles in vulnerability of rural areas including environmental elements such as stopping of incoming water flow into Hamoun Wetlands, winds of 120 days, wide geomorphological functions of moving sands, and high reduction in the density of vegetation and trees around and in the villages due to drought. In addition to the above factors, inconsistency of physical context of villages with the movement direction of moving sands has caused accumulation of sands in villages which is effective in vulnerability intensification of many rural areas.     Ruin of houses and cut of communicative roads by moving sands cause disruption in normal lives within the aforementioned villages. In addition to taking damages by moving sands into consideration, the evident role of state services is very significant in decreasing of the damages in all parts of Hirmand. In this connection, belt-like flood preventives built around the international Hamoun Wetlands has made moving sands accumulated behind them and this has decreased intensification of the damages and probable threats from sand onrush to the lower latitude regions.         Accordingly, the results of affecting level comparison of different factors in appearance or intensification of the moving sand’s effects in the villages under study revealed that the effects of weather factors and water restrictions sprung from hydrological droughts in which the incoming flow of Hirmand River into the area under study is cut or decreased remarkably, along with summer winds (winds of 120-days) and severe winter winds are more clear and stronger in intensification of soil erosion and formation of moving sands than other factors.        On the other hand, the results of impressionability level comparison of different contextual-spatial factors in the villages under study demonstrated that sand affects arable lands and water supply networks more than other factors.      However, given that reduction or stop of incoming water flow of Hirmand River into Sistan region over the recent years has caused successive droughts, some factors like drying of Hamoun Wetlands, intensification of environmental dryness, reduction of vegetation and increase of soil erosion along with Sistan’s winds of 120-days have paved the way for increasing of dust storms and movement of sands toward the villages of the region.