انتخاب مناسب ترين نوع گونه گياهي نبكا براي تثبيت ماسه هاي روان با استفاده از مدل AHP (مطالعه موردي: منطقه صمدآباد شهرستان سرخس)

Identifying the most suitable plant species form Nebkhas to stabilize sand movement by application of AHP model (case study: Samad-Abad, Sarakhs, Iran)

گياهان نبكا نقش مهمي در جلوگيري از حركت شن و ماسه هاي روان دارند و همچنين باعث توسعه نبكاها مي شوند. منطقه صمدآباد شهرستان سرخس تحت تاثير هجوم ماسه هاي روان به مراكز سكونتي، راه هاي ارتباطي و تاسيسات زيربنايي است. نبكاها در اين منطقه به عنوان يك سيستم تعديل كننده فشار فرسايش بادي و در نتيجه كنترل حركت ماسه هاي روان عمل مي كنند؛ بنابراين توسعه نبكا مي تواند عاملي جهت كنترل اثرات تخريبي ماسه هاي روان بر اكوسيستم طبيعي و انساني منطقه باشد. در اين راستا شناسايي سازگارترين گونه ي گياهي نبكا از اهميت بالايي برخوردار است. هدف از اين پژوهش ارزيابي مقايسه اي نبكاهاي منطقه صمدآباد شهرستان سرخس با استفاده از مدل AHP و معرفي مناسب ترين گونه ي گياهي نبكا براي تثبيت ماسه هاي روان از طريق تحليل مولفه هاي مورفومتري آن است. به اين منظور ابتدا مهمترين مشخصه هاي مورفومتري 120 نبكا نظير ارتفاع، طول و حجم نبكا و ارتفاع، محيط، طول و حجم گياه، از گونه هاي سبط پا كوتاه، اسپند و خارشتر با روش استفاده از ترانسكت اندازه گيري ميداني شد. سپس با ارزيابي مقايسه اي آنها از طريق مدل AHP، مبادرت به اولويت بندي نبكاهاي مطالعاتي شد. نتايج نشان مي دهد كه نبكاي گونه ي اسپند با وزن 0/4875 بيشترين ارجحيت و بهره وري را براي تثبيت ماسه هاي روان دارد. نبكاي گونه ي خارشتر نيز با وزن 0/3161 نسبت به نبكاي گونه ي سبط پاكوتاه از ارجحيت بيشتري برخوردار است كه دليل آن را مي توان تفاوت در ساختار مورفولوژي اين گياهان عنوان كرد.

Environmental crisis and the consequence loss of natural resources are the main reasons in which force the managers to think of the ways to manage risks and solve environmental tensions. One of the most problematic environmental issues in saad-abad region located at Sarakhs city, IRI, is the moving sands which attack residential centers, roads and the infrastructures. Therefore, environmental systems respond to the moving sands by nebkhas which balance the imposed pressure caused by wind erosion. Thus, nebkhas are considered as a significant factor to maintain the equilibrium among the forces created from environmental resistance powers and degrading moving sands imposed on residential systems. However, the most suitable plant species must be identified in order to manage the nebkhas to gain the aforementioned goals. The aim of this study is to identify the most suitable plant species in nebkhas in order to evaluate the amount of moving sands fixed in the study area using AHP model through morphometric characteristics. Study area This study was conducted in Saad-Abad as a center of wind erosion located in south parts of Sarakhs region, Iran, near Turkmenistan boundary and Tajan River with 35’ 58” to 36’17” longitude and 61’3” to 61’12” latitude, 21523 ha of area, 750 meters of average height from sea level, 187.6 mm of mean annual precipitation, 14.4 mean annual temperature and NW to SE dominant wind direction. Stipagrostis, Alhaji and Peganum showed to be the most suitable species for nebkhas formation. Materials and Methods Proceeding field investigations and satellite imagery analysis, the study area was determined. Using 6 transects (3 upwind and 3 leeward) each 100 meters long, we measured nebkhas morphometric characteristics (including height, length & volume) and plant characteristics (including height, perimeter & volume). Fourteen nebkhas were analyzed for each species (Stipagrostis, Alhaji and Peganum). AHP model was used in order to compare and determine the most suitable species for stabilizing moving sands. Results The final weight was calculate as 0.1964, 0.4875 and 0.3161 for Stipagrosis, Peganum and Alhagi, respectively. Therefore, as it is clearly explained by AHP model, Peganum is introduced as the most suitable plant species for stabilizing moving particles in the region proceeding with Alhagi. Conclusion Regarding nebkhas morphometric characteristics and plant morphological features as the input criteria for AHP model, the results introduced Peganum as the most suitable species for stabilizing moving sands proceeding with Alhagi and Stipagrosis.