نوع مقاله : مقاله پژوهشی
1 دانش اموخته دکتری رشته ژئومورفولوژی، دانشگاه خوارزمی
2 دانشیار دانشکده جغرافیا، دانشگاه خوارزمی.
3 دانشیار گروه جغرافیا، دانشگاه تربیت مدرس.
عنوان مقاله [English]
Climate geomorphology examines the effects of climate on earth surface processes and forms. Current landforms are shaped by different natural processes. External processes under the influence of climatic conditions of each region cause changes in the primary forms and create certain shapes. Morpho-climatic regions are the areas of the planet in which certain shapes and special patterns are formed under the influence of climate condition. Climate change is one of the main factors in shifting the boundaries of morpho-climatic areas. In recent decades, as a result of the increase in greenhouse gas emissions, it has affected different parts of the natural environment and made drastic changes in climatic conditions. These trends can lead to changes in morpho-climatic zones, including glacial areas, adjacent glaciers, temperate, arid, and semi-arid regions.
In this study, the effect of climate change for the year 2100 in Alborz province has been investigated. This province is very important in terms of nature as well as social and economic conditions. Naturally, it has a high morphological diversity. four morpho-climatic regions including the semi-glacier, temperate, semi-arid, and arid areas are developed in the province. These morpho-climatic regions depend on climatic conditions, and climate change can alter these territories. Therefore, it is assumed that the morphological conditions and geomorphic processes prevailing in the study area until 2100 due to climate change will change the boundary of morpho-climatic areas. As the result of the changes, arid and semi-arid morpho-climatic areas would be replaced by semi-glacial and temperate morpho-climatic areas.
In this study, meteorological data of 8 synoptic stations around Alborz province have been selected as study area. They have been used in different scenarios to reconstruct these parameters. Other information and maps have been extracted and prepared from topographic maps, satellite images, and Digital Elevation Model (DEM) of the study area.
Morpho-climatic zoning is based on the Peltier method using average annual temperature and precipitation. In order to reconstruct the temperature and rainfall values of these areas and estimate them for the year 2100, we have used CanESM2 model. The information has been reconstructed as a raster layer based on correlation relations with DEM. One of the most widely used micro-scale models based on multiple regressions is the SDSM model for creating conditional data. In this model, regression predictor variables are initially selected as independent variables. Then, after calibrating the model, the model is evaluated to predict future scenarios. The morpho-climatic zones are determined according to the Peltier model using the average temperature and annual precipitation layers with the help of Python scripting based on a spatial application in ArcGIS10.7.1 software. Finally, precipitation and temperature data have been prepared for the period 2070 to 2100, and based on these data, a morpho-climatic zoning map have been prepared for 2100 in the study area.
Results and discussion
Using total annual rainfall maps and average annual temperature, we initially developed the current state of the morpho-climatic areas, based on this map in Alborz province. Then, in the next step, the distribution maps of the total annual rainfall and the average annual temperature were prepared based on the climatic data reconstructed in the SDSM model for the year 2100 and based on three scenarios. Finally, we have made a zoning according to Peltier diagram based on spatial conditions in the region. The method helped determine the boundary of arid, semi-arid, temperate, semi-glacial and glacial morpho-climatic regions. In the three scenarios, in 2100, the area semi-arid and arid regions will be increased. The areas semi-glacier and temperate regions will be reduced respectively, in favor of expansion of the arid and semiarid areas. In three optimistic, moderate and pessimistic scenarios, 36, 47 and 49% of the area of the semi-glacier mopho-climatic zone and 2, 25 and 30% of the area of the moderate mopho-climatic zone have been reduced, respectively. In contrast, according to the optimistic, moderate and pessimistic scenarios, 1, 5 and 5% of the area of semi-arid mopho-climatic zone and 2, 5 and 7% of the area of arid mopho-climatic zone increased, respectively.
In the current situation, the area of the morpho-climatic zone of the glacier is less than one percent of the total area in the moderate and pessimistic scenarios have significantly decreased. The largest change in the province is related to the temperate morpho-climatic zone, which is mainly accompanied by an increase in arid and semi-arid regions. According to the presented results, it is possible to predict the reduction of the morpho-climatic areas of the glacier and adjacent glaciers in favor of temperate areas for the desired time. In particular, it should be noted that the occurrence of scenario 8.5 is more likely. Therefore, the continuation of the existing conditions can cause remarkable natural damages.
In this study, using a microscale model, it has been determined that the annual temperature and precipitation trends will be more developed towards drought and decrease in rainfall and change in the zones. Based on two moderate and pessimistic scenarios, three morphoclimatic zones of semi-glacier, glacier, and temperate regions are mainly located in the Alborz highlands. The areas will be reduced by 2010 in favor of arid and semi-arid zones. Found. Therefore, in general, it can be stated that in Alborz province, arid and semi-arid areas are increasing and glacial areas and adjacent glaciers and temperate areas are decreasing. This trend could change the shape of the effective morpho-climatic zones in this province until 2100, according to the current trend. The findings of this study show that the climatic conditions of the natural environment of Alborz province in the next hundred years will be accompanied by further expansion of arid and semi-arid regions. These changes will lead to changes in the surface conditions of the earth, including the intensity and weakness of vegetation and erosion. This will be a factor in the need for change in human activities in agriculture and industry.