Analysis of the geomorphological characteristics of the units and the formation of settlements in the North West province

the establishment and emergence of a city, more than anything else, principally depends on the natural environment and geographical location because the natural effects and phenomena have strong effect in localization, distribution, influence, physical and morphological development of urban areas. Most natural phenomena are plateaus, mountains, craters, valleys, plains and beaches, alluvial fans, slopes, rivers, seas, lakes, etc. (Zomorrodian, 8: 1995). Therefore, one of the most important studies in basic planning of settlements is identifying geomorphological phenomena and displaying them on a map of the same title (geomorphology). In fact, geomorphic and topographic features of a geographic place are not only effective in the dispersion or concentration of human activities, but also, eventually, it is one the factors influencing the shape and physical appearance spatial structures. (Ramesht, 102: 2005)
the purpose of preparing geomorphologic maps is recording information about the forms of surface, materials (soils and rocks), surface processes, and, in some cases, the age of land on these maps. The most successful approach to prepare such maps is the combination of field studies with the aerial photographs (Hosseinzadeh, 37: 2007). The first geomorphologic map of Iran, in a scale of 1:2500000, is among a set of maps of the near East in the University of Tubingen in Germany in 1990, which was produced and released by Servati, in collaboration with Bausch and Grounret; of course, some maps have been prepared by some colleagues of Tehran University, with the scale of 1:250000 and 1:50000. (JamshidJedariEivazi, FarajollahMahmoudi). The point which must be mentioned in this section is that this is the first large-scale geomorphologic map (1:25000) prepared in the vast eastern part of Guilan province (sarvar, 2002: 1-79). This article is part of a research project conducted by the author in the West of Gilan. (Shahmari, 2002: 1-45)
this study is a descriptive-analytical study which, based on the purpose, can be functional. Overall, the research process is as follows: the readiness and interest, experience and knowledge about the area, collecting large-scale topographic maps (1:25000) as the base maps, field visits and the observation of objects and phenomena on earth, drawing and producing primary map of land forms, geology and slope maps, analyzing data, aerial and satellite image analysis, and, finally, the analysis of results and producing the final geomorphologic map.
The study area is in the West of Guilan province and starts from the zero point of the border between Iran and Azerbaijan (the town of Astara) and includes the southern parts of Astara city, Talesh, Rezvanshahr, and Masal. It is located between ˝00 ´15 °37 to ˝00 ´27 °38 north latitude of the equator and ˝00 ´35 °48 to ˝00 ´14 °49 east longitude (topographic map 1:25000) and has 6/3839 square kilometers. The area under study is composed of two distinct morphology sections including:Mountainous Areas: an average altitude of 1500 meters above sea level, steep slopes, deep valleys and different streams on the slopes, existence of fault cliffs across the highlands of Talesh and other issues can be some of the restrictive geomorphologic factors in the development of settlements in the area of the study. Geomorphologic map of the mountainous area shows that the distribution of settlements of Aq Masjid (White Mosque), BaskemChal, Chamlar, Haji Amir, Vonabin, Heiran, Degarmankshi, Damiroughlikesh, Giladeh, Mashand, Dash Dibi, Baharestan, Latoun is influenced by the geomorphology (shape of the land). The things which are clearly visible in most areas are lack of flat land for the development and expansion of settlements.
Foothill Areas: have lower elevation than the surrounding mountainous areas, but, compared to the plain areas, have higher elevation and include from 100 to 500 meters, and, with a relatively gentle slope, extend a distance from mountains and connect to the plain. The main geomorphic elements of foothills region can be alluvial fan, concave and convex slopes, valleys and streams, cliffs, and the water path. Physical expansion of settlements usually encounters an obstacle while developing from one side. In the top of plains, the existence of mountain, high steep, rocks and boulder debris, and, overall, sediments are the major obstacles for spatial development.
The diversity of natural features and geographical positions has caused the heterogeneity and inconsistency in the creation, distribution, and density of urban and rural settlements in the study area so that, at the first glance, it is likely that the number of settlements in the East (toward the sea) region to the West (toward the mountains) is more; but studying the topographic maps of 1:25000, and analyzing the statistical data of the number of villages at different levels (Organization of Management and Planning, 2005, 37) suggests that, according to the increase in the height from the East to the West, the number of urban and rural settlements will increase in a way that, from among the total villages of 692 in the study area, 179 villages are on the shore (height of below zero meters), 115 villages in the plains (height of zero to 100 meters ); the total number of 294 villages which compose 48/42 per cent of the villages in the East of study area, and the rest of the 398 villages are in the West of study area from among which 109 villages are in the foothills (100-500), 294 villages in the mountain (above 500 maters), which, in sum, include 57.51 % of the whole villages in the west of Guilan province;in other words, the number of villages in the foothills and the mountains (toward the West) is more than the coast and the plains (toward the East) in a way that, from among the total number of 692 villages, 57.51 %, approximately 398 villages, are in areas of the foothills and mountains. Yet, despite a long record of residential issues in elevations (foothills and mountains), compared to the coastal areas and plains, due to the conditions of using this section, the number of population and density are high and the number and density of the population decreases from ....