جانمایی پهنه های مستعد ذخیره سیلاب با تاکید بر ویژگی های فرمی زمین و روش های تصمیمگیری چندمعیاره مکانی در حوضه ی آبخیز قمرود

انحراف و ذخیره سازی سیلاب روشی شناخته شده برای مقابله با مخاطرات و آسیب های سیل می باشد و از طرف دیگر سبب بهبود وضعیت کیفی و کمّی آب های زیرزمینی می شود و در واقع مهار سیلاب و تغذیه ی مصنوعی آبخوان ها از نتایج مهّم آن به شمار می رود. هدف این پژوهش جانمایی پهنه های مناسب ذخیره ی سیلاب حوضه ی آبخیز قمرود با استفاده از تکنیک تصمیم گیری چندمعیاره می باشد. در این پژوهش از متغیرهای شیب، خاک، کاربری اراضی، عمق آب های زیرزمینی، لندفرم، قابلیت نفوذپذیری سطحی، زبری، شاخص تجمعی جریان، لیتولوژی، ارتفاع و تراکم زهکشی به عنوان عوامل موثر در جانمایی جهت انحراف و ذخیره سازی سیلاب استفاده شده است. از مدل مجموع ادغامی مجموع حاصل ضرب (waspas) که یکی از جدید ترین مدل های تصمیم گیری چند معیاره می باشد برای تحلیل هم پوشانی و رتبه بندی گزینه ها و تهیه ی نقشه ی نهایی استفاده گردید. نتایج حاصل از مدل واسپاس نشان می دهد به لحاظ پتانسیل ذخیره ی سیلاب، حوضه ی آبخیز مورد مطالعه به پنج کلاس خیلی زیاد با 24 درصد، زیاد 28.2 درصد، متوسط 24.9 درصد، کم 15.2 درصد و خیلی کم 7.7 درصد تقسیم می شود. بدین ترتیب نه پهنه بسیار مناسب جهت انحراف و ذخیره سازی سیلاب در قسمت های مرکزی، جنوبی، شمال غربی و شرق حوضه شناسایی شد که این مناطق در بازدید میدانی نیز جهت اهداف مذکور مناسب تشخیص داده شدند.

The Selection of Susceptible Reservoirs to Flood Storage with an Emphasis on Landform Characteristics and Spatial MultiCriteria DecisionMaking Methods in Qomroud Watershed.

IntroductionA flood is an exceptional stream that may be flooded from the natural bed of the river. Usually, the maximum observed discharge during a year is named a flood or an annual flood. It is one of the natural disasters which has the highest damage in the world, after an earthquake. Losing life, land, and property, especially along the river, are among its most perilous environmental hazards. A comprehensive flood management seeks to use structural and nonstructural methods to prevent flood intensity and minimize its human and financial losses. Although we can minimize their damage, there is not any possibility of controlling floods. Qomroud Basin with an area of 3563 km2 (356300 hectares), is located in provinces of  Markazi and Qom and in a geographical position of  50°  2 33 to 50°  54 29 East and 33° 57  37 to 34°  39 28 north latitude. Its minimum and maximum heights are respectively 964 m and 3145 m and its average slope is 13.6 %.  The perimeter of the basin is 452.7 km and is part of the main catchment area of Iran’s central plateau. After several destructive floods with significant damage in recent years, especially after the huge flood of April 2009, the  need  for  desirable flood management in the Qomroud   River basin is very urgent.MethodologyThe purpose of this research was to control the floodwaters of the Qomroud Basin by determining the appropriate flood conservation areas using a multicriteria decisionmaking technique. Flood diversion and storage is a wellknown method for dealing with the risks and damage of a flood.  It can also improve the quality and quantity of underground water. In fact, flood control and artificial feeding of aquifers are among its important results. The Weighted Aggregates Sum Product Assessment (WASPAS) model is a new multicriteria decisionmaking technique (MCDM) that was introduced in 2012 and can be effective in complex decisionmaking issues. It is based on the combination of two models of multicriteria decision making WSM (weight aggregate model) and WPS (weighted production model) and is more accurate and has the ability to rank. Its application has four stages. In this hybrid model, it has been attempted to use a combined benchmark to determine the final importance of each option, which combines the parity contribution from WSM and WPS for the final evaluation of the options. In this study, the variables of gradient, soil, land use, groundwater depth, landform, surface permeability, roughness, accumulation flow index, lithology, elevation, and drainage density as effective factors in location for diversion and flood storage were used. The model (WASPAS) which is one of the most recent multicriteria decisionmaking models was used to calculate the indicators’ weights and rank the options and prepare the final map.ResultThe results obtained through this model have identified the areas susceptible to flood storage, with high accuracy and in the least possible time. Scoring each criterion is based on their relative importance. After determining the score of each criterion, a multicriteria evaluation of the GIS was obtained using the overlapping operation, WASPAS model, and the final map (synthesis) of land potential relative to the flood reserve. The relative heights of slope and land use were respectively 0.136, 0.12.  The relative weights of the height and the density of drainage were respectively 0.06 and 0.04, with the least importance for zoning susceptible flood reservoirs.Discussion and conclusionBy combining their results with the WASPAS model, it was possible to identify the susceptible areas to stormstoring with high precision and in the least possible time. The results showed that the Qomroud basin was divided into five classes including very high with 24 percent, high with 28.2 percent, moderate with 24.9 percent, low with 15.2 percent, and very low with 7.7 percent. Thus, there were nine very suitable areas found in the central, south, northwest and eastern parts of the basin for flood diversion and storage. The aforementioned areas were also recognized for field purposes for the desired purposes.