Efektywnosc metody TAM [Time-Area Method] w symulacji zmiennosci czasowej wydatku rumowiska ze zlewni Chehelgazi, Iran

The proper prediction of temporal and spatial variation of sediment yield from the watershed is a need for sediment control, river engineering and soil and water conservation studies. The present study was therefore planned to simulate the sediment graphs for Chehelgazi watershed in Gheshlagh dam upstream in Kurdistan Province, Iran, by using Time-Area Method. Towards this attempt, the study watershed was divided into 7 time-area segments based on the time of concentration. The soil erosion in each segment was estimated using the USLE and then routed to the main outlet using sediment delivery ratio as a function of land slope in two adjacent time-areas. The temporal variation of sediment was ultimately predicted with the help of lag time of sediment arrival to the outlet and the concept of superposition for 11 storm events, which occurred during winter 2006 and spring 2007. The comparison between estimated sediment graphs with corresponding observed ones verifi ed the weak capability of the model in simulation of sediment graphs under consideration. The results also verifi ed the calibration necessity of the model to achieve appropriate estimation for important components of the sediment graphs. The results of the calibration fi nally proved the considerable capability of the model in predicting of total volume of sediment yield with respective estimation and verifi cation errors of 30.93 and 33.40%.W artykule przedstawiono zastosowanie metody TAM do symulacji zmienności czasowej wydatku rumowiska ze zlewni Chehelgazi, położonej w prowincji Kurdystan w Iranie. Zlewnię Chehelgazi podzielono na 7 zlewni cząstkowych, biorąc za podstawę czas koncentracji odpływu rumowiska. Do wyznaczenia masy rumowiska transportowanego w czasie wezbrania opadowego wykorzystano uniwersalne równanie strat glebowych USLE. Na podstawie sedymentogramów 11 zarejestrowanych wezbrań opadowych przeprowadzono weryfikację i kalibrację metody TAM. Błąd estymacji i weryfikacji całkowitej objętości wydatku rumowiska ze zlewni wyniósł odpowiednio 30.9 i 33.4%

The effects of watershed physical properties on bed load morphometric and sedimentologic characteristics along downstream: a case study from Ghalesar watershed in Mazandaran Province

Litnology and sedimentology factors affect on downstream changes in bed load shape and can be useful to detect watershed hydrological processes as they are very important to design hydraulic structures and reservoir management. This research was conducted in Qalesar River in Mazandaran Province with main river length of 24 Kilometers. After recognition of the study area, 11 sections were selected toward downstream for bed load sampling. Laboratory analysis were done using gravel meter and sieving method to measure and calculate some bed load shape characteristics. Also physical properties of each sub-watershed were extracted using Arc/GIS 9.2 software. Finally, in order to determine most effective physical characteristics on bed load shape, data were analyzed using SPSS 16. Results of statistical analysis indicate the best model between D50 and length of 1 order channel in bivariate regression equations and between D50 and distance from upstream in multi-variate regression equations