آنتروپوژئومورفولوژي: نقش انسان در تغيير چهره زمين

Antropogeomorphology: The Role of Human in Modifying the Face of the Earth

آنتروپوژئومورفولوژي، شاخه تقريباً جديدي از علم ژئومورفولوژي است كه به بررسي نقش انسان در تغيير چهره لندفرم ها و اصلاح عملكرد فرايندهاي ژئومورفولوژيكي مانند هوازدگي، فرسايش، حمل و نهشته گذاري مي پردازد. افزايش ميزان فرسايش خاك در نتيجه تغيير كاربري اراضي، نمونه ايي از تاثيرات غير مستقيم انسان بر فرايندها و لندفرم ها است. با توجه به اينكه نرخ رشد جمعيت، شاخص مناسبي براي ارزيابي كيفي و كمي فرايندهاي متاثر از عملكرد انسان، نخواهد بود، معادله پتانسيل آنتروپوژئومورفولوژيكي معرفي شده كه دو عنصر اساسي آن درجه توسعه يافتگي(ميزان دخالت در محيط) و ميزان درك و آگاهي مردم) فرسايش ناشي از عملكرد انسان) است. بر اين اساس، هرچه درجه توسعه يافتگي و ميزان آگاهي هاي زيست محيطي مردم كمتر باشد، پتانسيل فرسايش ناشي از عملكرد انسان، افزايش خواهد يافت. براي ارزيابي پتانسيل آنتروپوژئومورفولوژيكي با استفاده از روش نير، 31 كشور از قاره هاي متفاوت انتخاب و مورد بررسي قرار گرفت و شاخصI آن ها بين 0-1، محاسبه شد. بر اساس نتايج به دست آمده، كشورها در سه گروه با پتانسيل آنتروپوژئومورفولوژيكي كم(I<0/03)، متوسط (0/03 ≤ I ≤ 0/49) و زياد(I ≥ 0/05) تقسيم بندي شدند. كشورهاي مجارستان، ايران و شيلي به ترتيب در گروه پتانسيل آنتروپوژئومورفولوژيكي كم، متوسط و زياد، قرار مي گيرند. بر همين اساس، اقدامات مقتضي مديريتي و مهندسي بايد انجام شود.

Antropogeomorphology is a new branch of geomorphology which investigates the role of human in changing landforms and the process of geomorphologic modification such as weathering، transport and deposition. Management and engineering related activities result in widespread changes in landscapes. Some landscapes such as terraces in arable lands، which are formed in farmlands and have completely different shapes، are the direct result of anthropogenic processes. Landforms produced by indirect anthropogenic process are not easily recognizable unless they are involved in the formation of natural processes. Such landforms are the result of environmental changes، which are brought about by human activities. One of the examples of such activities is the escalation in the rate of soil erosion due to over exploitation from forests. The main works done in this area include: Man and Nature(physical geography as modified by human action) by Marsh(1864)، Man as a Geological Agent(1922)، by Sherlock، The Human Impact(1981) by Goudie and Man as a Geological Agent by Nir(1983). Based on many studies about antropogeomorphology، the main fields are: mining، agriculture، settlements، water management، traffic، tourism، sports and industrial impacts on landforms. Material and Methods: The methods used in antropogeomorphology include: historical، socioeconomic and geomorphological approaches. In this paper socioeconomic behavior، Degree of Development (DD) and Degree of Perception (DP) on rate of geomorphological process investigated. On this basis، in Index of Potential Anthropic Geomorphology (I)، the percentage of urban population and percentage of illiteracies indicates degree of development and perception of people resp. The required data can be obtained from international statistical yearbooks. To calculate of effects of climate and topography، the constants Kc and Kr are used. Values of these constants may range from 0.4 to 0.8، (climate) and from 0.2 to 0.8، (topography). (Table 2). According to equation 3، I index 31 selected countries calculated and presented in table 3.Then، I index of selected countries divided into three groups. The final map (fig 5) was drowning on this basis and finally analyzed. Easy of access to data is one of the benefits of Nir method. Results and Discussions: Considering the fact that the rate of population growth is not a suitable factor in quantitative and qualitative assessments of human activities; therefore، antropo-geomorphologic potential equation (eq، 3) is introduced. Two important factors such as the degree of development (rate of human interface in environment) and human perception (human induced erosion) form this equation. Based on this formula، there is a direct relationship between the degree of development and environmental perception on the one hand and the rate of erosion on the other. For assessing the potentiality of antropogeomorphology، 31 countries from different continents were analyzed. The I index have a values between 0-1(Table 3). Conclusions: Based on Nir (1983)، classification of Index of Potential Anthropic Geomorphology (I)، the results of calculations are presented in table 3. The potentiality of antropogeomorphology in developed and poor countries are different. Moreover، these calculations indicate in three interval times. In some countries for example Iran، Turkey، India and Greece، trend of I index were regressive. - In countries such as Hungary، Thailand and Poland، I<0.30، the risk of human geomorphologic activities is low. - In some countries for example USA، South Korea، Philippines، Bulgaria، United Kingdom and Iran، 0.30 ≤ I ≤ 0.49، the risk is not negligible and some management activities should be taken. - Countries such as Algeria، Morocco، Chile and Nepal have the highest I index، (I ≥ 0.50)، considerable damage followed by antropogeomorphological process. Engineering appropriate and immediate should be taken in these countries.