ساختار فيزيكي رودخانه مادرسو پارك ملي گلستان

Physical structure of the Madar-Sou stream in Golestan National Park

Understanding ecological processes and associated complexities of river systems play an important part in defining their role and value as a unique ecosystem. Structural assessment of rivers helps to gain such an understanding, and ultimately is useful in interpreting relationships between abiotic and biotic components of the system. In the present study, scientific methods were used to assess the physical structure of the Madar-sou stream over the years 2000 - 2001. The length of Madar-Sou stream in Golestan National Park was measured as 19,913 m., 84/6 % of which were riffles and the remaining was recognised as pools. These charateristics increased the biological and physical diversity of the stream. The number, length and width of pools were varied from headwater (Sar-Cheshmeh) to downstream (Tangerah). A maximum number of 29 pools were sited along the 16th - 17 th km from the headwater and a minimum of 2 pools were recorded in the headwater up to a length of 1 km. The maximum and minimum width of pools were 3.75 and 1.86 m respectively. The maximum depth of pools was 120 cm. Gravel was the dominant bed structure. Overall, 370 pools were detected in the stream. The variation in the width of stream showed an irregular pattern and the medium width was about 5-6 m. The maximum height from sea level was 760 m in headwater and the minimum was 420 m in Tangerah. The direction of water flow in the stream was very varied but the dominant direction was from east to west. Madar-sou stream has a lot of variation in water level in different months and has many tributaries (convergent and divergent). The slope of stream ranged between % 1.5 - 2. The Information gathered in this study makes it possible to provide physical map of the stream at scales of 1:1000 to 1:50 000. The maps and the information can be used in studies of interrelationship between the abiotic and biotic components of the stream and thus upgrade the ecological management of the system.