Environmental Erosion Research
پژوهش هاي فرسايش محيطي
E.E.R.
Literature & Humanities
http://magazine.hormozgan.ac.ir
1
admin
2251-7812
2717-3968
10.52547/jeer
6561
8888
45855/11/3/90
fa
jalali
1396
2
1
gregorian
2017
5
1
7
1
online
1
fulltext
fa
مدلسازی پتانسیل رخداد فرسایشهای آبکندی در منطقهی سیمره با استفاده از مدلهای آنتروپیشانون و شاخص آماری
Modeling the Potential of Gully Erosion Occurrence Applying Shannon Entropy and Statistical Index Models in Seymareh Region
روشهای نوین و دقیق در تهیّه نقشه فرسایش (سنجش از دور و سیستمهای اطلاعات جغرافیایی)
پژوهشي
Research
<p><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">وقوع فرسایش­های آبکندی به دلیل تولید رسوب بالا در حوضه­های آبخیز، یکی از مشکلات منابع طبیعی در زمینه­ی مدیریت و حفاظت خاک تلقی می­شود. در این تحقیق، پتانسیل وقوع فرسایش آبکندی براساس مدل­های آنتروپی شانون و شاخص آماری در منطقه­ی سیمره استان لرستان ارزیابی شد. ابتدا لایههای رقومی عوامل مؤثر در پتانسیل مناطق حساس به فرسایش شامل ارتفاع، سنگشناسی، شیب، جهت شیب، کاربری اراضی، فاصله از رودخانه، رده خاکشناسی، شاخص رطوبت توپوگرافی و شاخص توان جریان در محیط نرمافزار </span></span></strong><strong><span dir="LTR"><span style="font-size:12.0pt;">ArcGIS 10.2</span></span></strong> <strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">تهیه شد. از </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:11.0pt;">100</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> آبکند موجود، گروه آموزشی (</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:11.0pt;">70</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> درصد) و اعتبارسنجی (</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:11.0pt;">30</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> درصد) به صورت تصادفی تفکیک شد. سپس وزن کلاسهای هر یک از عوامل مؤثر، براساس تجزیهوتحلیل احتمالاتی مدل­های شاخص آماری (</span></span></strong><strong><span dir="LTR">SI</span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">) و آنتروپی­شانون تعیین گردید. نقشه­ی حساسیت به فرسایش آبکندی نیز براساس این مدل­ها تهیه شد. در نهایت، اعتبارسنجی نقشه­ی نهایی براساس دادههای گروه اعتبارسنجی و روش منحنی مشخصه­ی عامل گیرنده (</span></span></strong><strong><span dir="LTR">ROC</span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">) انجام شد. نتایج نشان داد نقشه­ی حساسیت به فرسایش آبکندی که براساس مدل­های آنتروپی­شانون و شاخص آماری تهیهشده، به ترتیب دارای میزان اعتبار </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:11.0pt;">3/77 </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">درصد و </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:11.0pt;">8/79</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> درصد است؛ این امر بیانگر قابلیت بالای این مدل­ها در شناسایی مناطق حساس به فرسایش آبکندی است. علاوه بر آن براساس نتایج مدل آنتروپی­شانون، عوامل سنگ­شناسی، ارتفاع و کاربری اراضی بیشترین تأثیر را در وقوع فرسایش­های آبکندی داشتند. تعیین میزان حساسیت مناطق مختلف نسبت به فرسایش آبکندی برای اجرای برنامه­های حفاظتی ضروری است که تحقیق حاضر این مهم را فراهم می­کند.</span></span></strong></p>
<p><strong>1- Introduction</strong><br>
The gully erosion occurrence, due to the high rate of sediment production in the watershed, is one of the problems of natural resources management in the context of soil management and protection. It is known as an important signature of land degradation and forming as well as a source of sediment in a range of environments. Gully erosion often has severe environmental and economic ramifications worldwide such as destroying soil, damaging agricultural fields<span dir="RTL">,</span> undermining infrastructure, altering transportation corridors, and degrading surface water quality, which can be difficult to reverse. In this study, the potential of gully erosion occurrence was evaluated using Shannon entropy and statistical index models in the Seymareh region of Lorestan province. Firstly, digital layers of gully conditioning factors including altitude, lithology, slope angle, slope aspect, land use, distance from river, soil, topographic wetness index and stream power index were produced using ArcGIS 10.2. In modeling the gully erosion occurrence, the mentioned factors were regarded as independent variables and gully erosion occurrence was considered as dependent variable, whose interrelations will be determined based on Statistical Index and Shannon's entropy models.<br>
<br>
<strong>2- Methodology</strong><br>
Initially, a gully erosion inventory was prepared through a field survey. An inventory of 100 gullies was randomly divided into training group (70 %) and validation group (30 %). The weight of each conditioning factor was determined through the probability analysis of Statistical Index and Shannon's entropy models. The weights of gully conditioning factors were specified in each model based on the frequency and density of gullies. These weights were associated to each class of conditioning factors in GIS environment. Then, the map of gully-prone areas was produced using both models. Subsequently, the produced maps were validated using receiver operating characteristic (ROC) curve method and validation group. The area under this curve (AUC) was calculated for the quantitative comparison of models performances. Finally, the gully erosion potential values were reclassified into four levels, including ‘low’, ‘medium’, ‘high’, and ‘very high’ susceptibility, using the natural breaks.<br>
<br>
<br>
<strong>3- Results </strong><br>
The results showed that the generated maps based on Statistical Index and Shannon's entropy models have the prediction accuracy rate of 77.3 % and 79.8 %, respectively, implying that these models are capable of detecting gully-erosion-prone areas. In addition, according to the Shannon entropy results, lithology, elevation, and land use were represented as having significant effects on the gully erosion occurrences. Visually, the highest gully erosion susceptibility of the Seymareh region was located on the center, eastern and western parts of the study area where the lithology and land use are Quaternary deposits and agriculture, respectively. From a geomorphological point of view, the areas with gentle slopes, located in high TWI and near the streams show a high gully erosion susceptibility.<br>
<strong>4- Discussion and </strong><strong>Conclusions</strong><br>
These models exhibited acceptable cases of accuracy for the area under study<span dir="RTL">,</span> indicating that they are highly appropriate for gully erosion susceptibility mapping. This study, not only analyzed the relationship between the gully erosion inventory and geo-environmental variables, but also illustrated susceptibility to gully erosion based on statistical analysis of conditional probability technique. Determining the susceptibility level of different regions in terms of gully erosion occurrence in order to measure the soil erosion protection is necessary, which was provided in the current study. The results of the study can provide useful information to understand gully erosion mechanisms and scientific policy-planning and decision-making in the semi-arid regions. </p>
اعتبارسنجی, پیشبینی مکانی, مدیریت و حفاظت خاک, متغیرهای زمین- محیطی
management and protection of soil, validation, geo-environmental variables, spatial prediction
69
89
http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-450-1&slc_lang=fa&sid=1
سمیرا
قربانی
samiraghorbani.897@gmail.com
10031947532846003683
10031947532846003683
Yes
گروه مرتع و آبخیزداری، دانشکدهی کشاورزی و منابع طبیعی، دانشگاه لرستان
امید
رحمتی
orahmati68@gmail.com
10031947532846003684
10031947532846003684
No
گروه مرتع و آبخیزداری، دانشکدهی کشاورزی و منابع طبیعی، دانشگاه لرستان
فرهاد
نورمحمدی
fnoormohamadi@gmail.com
10031947532846003685
10031947532846003685
No
گروه مرتع و آبخیزداری، دانشکدهی کشاورزی و منابع طبیعی، دانشگاه لرستان