Study of Bioclimatic Condition of the Qahvand Plain in Hamedan Province, and its Role in Desertification

Qahavand plain is a natural sedimentary stretch of subsiding land with gentle slopes located between steep slopes of Alvand mountain, Shazand and Vassal heights and and semi – mountainous areas in east of Hamedan Province. The area is probably a continuation of the Massileh of Qom. The Qahavand region was first delineated using Topography maps at 1:50,000 and 1:25000 scales and soil sampling points were determined using aerial photographs at 1:20000 scale, while in the process the software ArcGIS9 and Excel, were used. Observations were recorded for bioclimatic features of the area with regards to geological, hydrologic and soil characteristics. We found that the present pedimont has been developed and extended in the region under geomorphologic and morphodynamic conditions along with bioclimatic characteristics specially under dry and semi – dry regional conditions . It seems that the plain has been under influence from successive processes of destruction and erosion and under climate conditions of the past and present. These processes have caused the creation of this dry region similarly to those that have shaped the central regions of Iran like Kavir playa. It seems that in creation of a dry region like Qahavand, the time and location of currents and streams and its vicinity to the central region of Qom, intense evaporation and shortage of water and negative balance of water, and in general natural factors like regional hydrologic, geomorphologic, pedologic and plant conditions and human factors like farming, extensive grazing and other factors are the effective factors. These factors have caused the creation of a special bioclimatic environment with characteristics of desert regions.