Environmental Erosion Research

fa بررسی کمی میزان فرسایش و رسوب جاده‌های جنگلی شهرستان لردگان با استفاده از مدل SEDMODL Quantitative investigation of erosion and sedimentation of forest roads in Lordegan County using SEDMODL مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی پژوهشي Research <div style="text-align: justify;">یکی از بزرگترین مشکلات ناشی از جادهسازیهای غیراصولی، وقوع اشکال مختلف فرسایش از قبیل فرسایش آبکندی و توده‌ای وتشدیدآن ها در اطراف جاده‌ها است. در پژوهش حاضر از مدل تحویل رسوب جاده (SEDMODL) و سیستم اطلاعات جغرافیایی برای تخمین میزان و درصد رسوب‌دهی متوسط سالانه ناشی از شبکه جاده‌های جنگلی در جنگل‌های بلوط غرب کشور در استان چهار محال و بختیاری استفاده شد. در این تحقیق از جاده‌های جنگلی بیدله واقع در شهرستان لردگان به طول 5828 متر که به صورت خاکی و عمدتا جهت سهولت دسترسی به مناطق جنگلی، مسکونی (روستا) ، عشایری و تفریحی در مناطق جنگلی استان چهار محال و بختیاری احداث شده است به عنوان منطقه مطالعاتی استفاده شد. ابتدا نقشه‌های مورد نیاز شامل زمین‌شناسی، مسیرجاده، شیب، بارندگی و تراکم زهکشی تهیه و در محیط نرم افزار Arc GIS 10.8 رقومی شد و همچنین طی بازدید‌های میدانی جنس، سن و ترافیک جاده‌های مطالعاتی تعیین گردید. فرمول‌های به‌کارگرفته شده در SEDMODL بر پایه روابط ریاضی و کمی بین عامل‌های فرسایش از قبیل نوع استفاده از جاده، ترافیک جاده، مواد مادری به کار گرفته شده در احداث جاده، وضعیت سطح جاده، شیب طولی جاده، پوشش گیاهی ترانشه خاک‌برداری، میزان بارش منطقه و میزان فاصله از آبراهه طراحی شده‌اند. همچنین در این تحقیق به منظور اندازه‌گیری میدانی میزان فرسایش و رسوب در قسمت‌های مختلف جاده‌های مطالعاتی 30 پیکه فرسایشی نصب و در طول یک سال میزان تغییرات آنها به کمک متر لیزری با دقت 02/0 میلیمتر اندازه‌گیری شد و میانگین فرسایش خاک بر اساس اندازه‌گیری صورت گرفته 4 میلیمتر در یک سال برآورد شد. میزان فرسایش بر اساس مدل SEDMODL در جاده بیدله 2068 تن در سال و میزان رسوب دهی کل بر اساس مدل SEDMODL 234 تن در سال است. همچنین آنالیز لکه‌های داغ نشان داد 8/39 درصد از جاده‌ها دارای تولید فرسایش بسیار زیاد می باشند.</div> <div style="text-align: justify;"> 1- Introduction The road sediment delivery model (SEDMODL) and geographic information system were used to estimate the amount of average annual sedimentation caused by the forest roads network in the oak forests of the west of the country in Chaharmahal and Bakhtiari provinces. In this research, Bideleh forest roads in Lordegan County with a length of 5828 meters selected. The area maps including geology, road networks, slope, and rainfall and drainage density were prepared and digitized in the Arc GIS 10.8 software, and also during field visits, the type, age and traffic of the study roads were determined. The formules used in SEDMODL are based on mathematical and quantitative relationships between erosion factors such as the type of road, road traffic, and parent materials used in road construction, road surface condition, road longitudinal slope, vegetation cover, excavation trench, the amount of rainfall in the area and the distance from the waterway. Also, in this research, in order to measure the amount of erosion and sediment in the field, 30 erosion markers were installed in different parts of the study roads, and during one year, their changes were measured with the help of a laser meter with an accuracy of 0.02 mm. The average soil erosion was estimated 4 mm per year based on the measurements. According to the SEDMODL model, the amount of erosion in Bidleh road is 2068 tons per year and the amount of sedimentation is 234 tons per year according to the SEDMODL model. Also, the analysis of hot spots showed that 39.8% of Bideleh forest roads have very high erosion. 2- Methodology Sediment production from a road is usually influenced by three types of water flow on the road surface, soil removal trench and roadside waterways. In fact, the model used in this research (SEDMODL) is based on these three factors (Akay et al. 2008). Therefore, the total precipitation in tons per year from each road section is calculated based on the equation 1. (Equation 1) Total Sediment (t/year) = (TS+CS)*Af In the above equation, TS is sediment production from road surface and roadside waterways, CS is sediment production caused by soil removal trench and Af is the age factor of the road. According to equation 2, TS is also affected by road length (Lr), road width (W), geological erosion rate (GEr), road surface material (Sf), traffic (Tf), road slope (Gf), rainfall. (Pf) and sediment delivery factor (Df). (equation 2) TS = Lr* Wr*GEr* Sf*Tf* Gf*Pf*Df Also, sediment production caused by soil removal trench CS according to equation 3, a function of geological erosion rate factors (GEr), vegetation and stone cover around the road (CSf), soil removal trench height (CSh), road length (Lr) and the sediment delivery factor (Df).   (equation 3) CS = GEr*CSf*CSh* Lr*Df Sediment production of the road during the first and secondry years of construction until the excavation trench and embankment pile is properly fixed by vegetation has its maximum amount. In SEDMODL, the effect of the road age factor (Af) is 10 in the first year of construction and 2 after two years. The values for other erosion factors was obtained from the provided tables of the model which were calculated based on previous researches (Akay et al. 2008; Naghdi et al. 2017). For field measurement of erosion on the forest road, 30 wooden rods were installed around the road. The wooden rods were installed in the sections perpendicular to the road in different conditions of geology, vegetation and the slope of the road and on both sides of the road at intervals of 5 meters, 15 meters and 25 meters. Then, the height of each rod was measured using a laser meter with an accuracy of 0.02 mm. The height of each rod was measured in 5 times and the average of these values was determined as the height of the rod in each stage. 3- Results Chaharmahal and Bakhtiari province with an area of about 1,632,835 hectares is located between 31◦ 9′ to 32◦ 48′ north latitude and 49◦ 28′ to 51◦ 25′ east longitude. Bidele road is located 30 kilometers west of Lordegan city and in the western part of Bideleh village of this city. The length of road study is 5828.6 meters. This road has the dirt and sand bed, with an average width of 4.5 meters and extends in a forested and mountainous area in order to access telecommunication towers and power transmission lines. In this research, the required maps including geology, road, slope, rainfall and waterway network were prepared by using topography, geology, satellite images and field visits related to relevant organizations. In the next stage, during field investigations, factors such as road surface, traffic, height of excavation trench were extracted. The digital layer of waterways was extracted from the existing topographical map in the area and possible errors were corrected by field controles. Also, the slope map of the area was determined using the digital elevation model prepared from the topographic layer. In order to prepare the precipitation map, the rainfall annual average near the roads was used and the annual precipitation layer was prepared for each region. In this way, the geological erosion rate factor GEr, the traffic factor Tf, the road slope factor Gf, the precipitation factor Pf, the sediment delivery factor Df, the vegetation and stone cover factor around the road CSf and the height factor of the excavation trench Chf for the study road of Bideleh were calculated as vectors and was determined numerically. Based on the prepared factors related to the model that was prepared digitally and on the study road, finally, the sediment production of the road surface and the sediment production of the excavation trench were determined and extracted separately (Table 1). Table 1: Total sedimentation estimation of SEDMODL sediment delivery model on Bidleh road <table class="TableGrid2" style="border-collapse:collapse; border:none"> <tbody> <tr> <td style="border-bottom:1px solid black; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">Road Name</td> <td style="border-bottom:1px solid black; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">Road length</td> <td style="border-bottom:1px solid black; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">Af</td> <td style="border-bottom:1px solid black; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">TS (ton/year)</td> <td style="border-bottom:1px solid black; width:93px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">CS (ton/year)</td> <td style="border-bottom:1px solid black; width:111px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">Total Sediment (ton/year)</td> </tr> <tr> <td style="border-bottom:none; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">Bidleh</td> <td style="border-bottom:none; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">5828</td> <td style="border-bottom:none; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">2</td> <td style="border-bottom:none; width:102px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">103.8</td> <td style="border-bottom:none; width:93px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">13.3</td> <td style="border-bottom:none; width:111px; padding:0cm 7px 0cm 7px; border-top:none; border-right:none; border-left:none" valign="top">234</td> </tr> </tbody> </table> 4- Discussion & Conclusions In order to study and investigate the role and influence of the measured parameters and input to the model on the rate of erosion, Pearson's correlation test was used and its results are presented in Table (2). As the results of the statistical correlation test show, there is the strongest significant correlation between the erosion rate of the whole road with geological factor, road width and precipitation factor. As it was mentioned, with the construction of the road, the vegetation and soil of the areas around the road will also change due to soil removal. To compensate these changes and return to the initial conditions, the ecosystem needs time. It is obvious that the longer the life of these changes, the closer the ecosystem is to a stable state, and the amount of soil erosion and destruction is less. Table 2: Pearson correlation analysis results <table class="Table" style="width:99.0%; margin-left:1px; border-collapse:collapse" width="99%"> <tbody> <tr> <td colspan="2" style="border-bottom:1px solid black; width:18%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none"></td> <td style="border-bottom:1px solid black; width:7%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">TotalE</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none"> GEr</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">CSh</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">CSf</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Pf</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Gf</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Tf</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Sf</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">W</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Lr</td> </tr> <tr> <td rowspan="3" style="border-bottom:none; width:7%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none" valign="top">TotalE</td> <td style="border-bottom:1px solid black; width:10%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Pearson Correlation</td> <td style="border-bottom:1px solid black; width:7%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">1</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.882**</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.250**</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.079</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.393**</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.269**</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.328**</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.247**</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.493**</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">-.080</td> </tr> <tr> <td style="border-bottom:1px solid black; width:10%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">Sig.</td> <td style="border-bottom:1px solid black; width:7%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none"></td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">-.064</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">.000</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">  -.062</td> </tr> <tr> <td style="border-bottom:1px solid black; width:10%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">N</td> <td style="border-bottom:1px solid black; width:7%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:8%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> <td style="border-bottom:1px solid black; width:6%; padding:0cm 0cm 0cm 0cm; background-color:white; border-top:none; border-right:none; border-left:none">370</td> </tr> <tr> <td colspan="12" style="width:100%; padding:0cm 0cm 0cm 0cm; background-color:white" valign="top">**. Correlation is significant at the 0.01 level </td> </tr> <tr> <td colspan="12" style="width:100%; padding:0cm 0cm 0cm 0cm; height:5px; background-color:white" valign="top">*. Correlation is significant at the 0.05 level </td> </tr> </tbody> </table> This tool is used for points that have a numerical characteristic (such as the rate of soil erosion or sedimentation) or the weight of complications. The result will be a map that shows hot and cold spots that have significant statistical characteristics. Analyzes are based on Getis ord GI statistics. In this research, this analysis was used to identify areas with high erosion rates (hot spots of road erosion). Also, the results of this part of the research showed that with a confidence level >95%, 39.8% (2321 meters) of the road is identified as areas with high erosion production and as hot spots. Based on the prepared maps in this part of the work, it was found that the soil erosion rate is higher in the areas with high slope and geologically sensitive, and these parts play the biggest role in the production of sediment in the area.</div> <div dir="rtl"></div> تلفات خاک, جنگل‌های زاگرس, راه‌سازی, مدل ریاضی Soil loss, Zagros forests, Road construction, Mathematical model. 41 57 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-1003-1&slc_lang=fa&sid=1 Sayed Naeim Emami سیدنعیم امامی emami1348@yahoo.com 10031947532846008824 10031947532846008824 Yes Soil Conservation and Watershed Management Research Department, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Centre, AREEO, Shahrekord, Iran. خش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی چهارمحال و بختیاری، شهرکرد، ایران. Saleh Yousefi صالح یوسفی ssaleh.yousefi@yahoo.com 10031947532846008825 10031947532846008825 No Soil Conservation and Watershed Management Research Department, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Centre, AREEO, Shahrekord, Iran. بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی چهارمحال و بختیاری، شهرکرد، ایران. mohammad Nekooeimehr محمد نکوئی مهر m_nekooeimehr@yahoo.com 10031947532846008826 10031947532846008826 No Soil Conservation and Watershed Management Research Department Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Centre, AREEO, Shahrekord, Iran. بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی چهارمحال و بختیاری، شهرکرد، ایران.