ارزیابی میزان اثرگذاری عناصر ساختاری سطح زمین بر تناسب اراضی برای کاربری‌ها مختلف (مطالعه موردی: شهرستان ارومیه)

از دیدگاه آمایشی، توسعه فعالیت‌های اقتصادی بدون توجه به توانمندی‌ها و میزان ظرفیت تولیدی منابع طبیعی موجود منطقه، مشکلات متعدد زیست‌محیطی، اجتماعی و اقتصادی را به‌وجود می‌آورد؛ از این‌رو در هر منطقه‌ای، به‌ویژه مناطق کوهستانی مانند ارومیه، شناخت و مدیریت صحیح پارامترها و منابع محیطی برای حفظ پایداری زمین و منابع امری مهم و اجتناب‌ناپذیر است. هدف پژوهش حاضر بررسی و شناسایی میزان اثرگذاری عناصر ساختاری زمین بر تناسب کاربری‌هاست که با بهره‌گیری از سیستم اطلاعات جغرافیایی و روش mce برای ارزیابی و مطالعه بیشتر زمین در شهرستان ارومیه انجام شده است. نتایج این پژوهش نشان می‌دهد عناصر توپوگرافی و لندفرم‌ها نقشی برجسته‌ در غربال‌گری تناسب زمین برای توسعه فعالیت‌ها دارند. براساس نتایج این مطالعه، درمجموع تنها حدود 33 درصد کل مساحت شهرستان ارومیه برای توسعه فعالیت‌های مختلف در پهنه‌های بسیار متناسب و متناسب قرار دارد. در فرایند مطالعه، نتیجه هم‌پوشانی لایه شیب بر پهنه‌بندی پیشنهادی نشان می‌دهد پهنه‌های تناسب محدود، تناسب بسیار پایین و نامتناسبی با میانگین شیب‌های 18/20 درصد، 69/28 درصد و 42 درصد مشتمل بر 67 درصد مساحت شهرستان دارد، اما توانمندی لازم برای توسعه فعالیت‌ها را ندارد و عملاً محدودیت‌های شدید محیطی ناشی از توپوگرافی و لندفرم‌ها، مانع اصلی توسعه فعالیت‌ها در این محدوده‌هاست. براساس این نتایج می‌توان به‌خوبی دریافت که در منطقه ارومیه، نیل به توسعه در هر فعالیتی مستلزم توجه و اولویت ملاحظات محیطی و مدیریت پایدار منابع طبیعی منطقه است.

Evaluation the Effects of Terrain Basic Components on Land Suitability for Developing Activities in Urmia County

IntroductionIn the contemporary era, vital environmental resources such as water and soil have degraded resulting from increasing population, development of environmentally harmful activities, inappropriate management and so on. Today, development beyond ecological thresholds and degrading the main factors of development and human survival has turned into one of the major challenges of human society. If this trend continues, the world society will face with various problems such as food security, environmental conservation and preservation of natural heritage. From perspective of land use planning, development of economic activities without taking into account the potentials and the degree of production capacity of land resources can bring about various environmental, social and economic problems in a specific region. Therefore, at any region, especially mountainous areas like Urmia, understanding and appropriate management of land resources and its parameters is necessary and unenviable for land sustainabilityConsidering the physical conditions of land such as topography and landforms in Urmia region, which making sever limitations for development, it seems that analyzing of land characteristics and identifying limitations and potentials of this region can be used as an effective tool for land users in terms of developing activities. The present study is aimed at answering this critical question that: how much topographic and landform conditions can affect on land suitability for developing activities in Urmia County. The result of this study will lead a base map which can make a background for further evaluation of the land for determining various land uses in the region. MethodologyIn order to identify suitable classes for developing activities, the Multi Criteria Method was used. MCE is a method for combining data according to their importance in making a given decision. At a conceptual level, MCE methods involve qualitative or quantitative weighting, scoring or ranking of criteria to reflect their importance to either a single or a multiple set of objectives (Heywood and et al., 2006: 239). Over the last decade or so, a number of multiattribute (or multicriteria) evaluation methods have been implemented in the GIS environment including WLC and its variants, ideal point methods, concordance analysis, and analytic hierarchy process (Malczewski, 2004: 34). Among these procedures, the WLC and Boolean overlay operations are considered the most straightforward and the most often employed (Chen & et al., 2001: 387; Malczewski & Rinner, 2005: 250; Malczewski, 2006: 270; Lafortezza & et al., 2008: 194; Boroushaki & Malczewski, 2008: 399; JelokhaniNiaraki & Malczewski, 2015: 493). WLC (or simple additive weighting) is based on the concept of a weighted average. The decision maker directly assigns the weights of ‘relative importance’ to each attribute map layer. A total score is then obtained for each alternative by multiplying the importance weight assigned for each attribute by the scaled value given to the alternative on that attribute, and summing the products over all attributes. When the overall scores are calculated for all of the alternatives, the alternative with the highest overall score is chosen (Malczewski, 2004: 34).Results and discussionOperations of overlaying layers1. Producing Map AIn order to produce map A, at first stage, slope and elevation parameters were compared. The Statistics results of this map show that the highly suitable and suitable classes cover 31.66 and 30.31% of the total area, respectively. The results also show that the combination of the slope and elevation layers has placed approximately 40% of the total areas in limited and not suitable classes. 2. Map BIn order to produce map B, the standardized layer of aspect is overlaid with map A. The results of the topographic map indicate that only 21 percent of the total area is highly suitable for developing activities. In the second class, i.e. suitable, which cover 22 percent of the total area, the lands are suitable for some activities. 3. Map CBy overlaying land type and map B and producing map C, more filtering was applied in structural land layers for developing activities. This phase can be regarded as the milestone of the layers overlaying process. In other words, in this step, by adding land type layer, main characteristics of land combined and the geomorphology map the region was completed. By producing geomorphology map, the area of the highly suitable was decreased, significantly. Therefore, the area of the highly suitable decreased to 13.02 percent, which indicate the highly effeteness of the land type in filtering among natural parameters for developing activities. Producing Final Land SuitabilityIn final map, the drainage layer as an effective parameter was used in the analysis. The drainage map generated from river density and line density function. The results of this map show that approximately 11 and 21 percent of the total area is highly suitable and suitable, respectively. By adding drainage layer to geomorphology map, the areas of the two mentioned classes were significantly decreased. According to final land suitability map, 33 percent of the total area is highly suitable and suitable, 28 percent marginally suitable and 38 percent not suitable.ConclusionThe results of parameters overlay showed that in all of the steps topographic elements have significant role in filtering of land suitability for developing activities. The results of the overlaying land evaluation map and slope with proposed land suitability demonstrate that the classes of marginally, very low and not suitable, with slope of 20.18, 28.69 and 42 percent, respectively, have severe natural limitations and the possibility of developing activities is not practical in approximately 67 percent of the total area. Therefore, topographic and landform characteristics of the region are the main constraints in developing of the activities in Urmia County. Based on these results, achieving to any activity development in Urmia requires to prioritize and take into consideration environmental issues and sustainable management of natural resources. Keywords: Topography, Landform, Urmia County, Geographic Information System, MCE Method