مجله ترویج و توسعه آبخیزداری
پیاپی 6 (پاییز 1393)

The problem of reservoirs dam sedimentation have been serious in the recent years and after other reservoir dam establishment will be more importance. On the other hand, the estimation of suspended sediment load that is main part of sediment input to reservoirs dam major amuse mind of sediment scientists. The precise estimation of sediment rate has been need in the problems such as reservoirs design, sediment transportation, lake pollutant estimation, channels design and digging sediment after floods, estimation of sedimentation hazards to environment and watershed management effects determination. In this research, the daily discharge data of Lar-Poloor station from 1968-1969 to 1999-2000 were used. Whereas Lar dam was constructed in 1980, maximum, mean and minimum discharge and sediment rate was compared for two period, before and after of dam construction. The results of this research showed that totally maximum, mean and minimum sediment in before construction of dam had been more than compare with after dam construction. These results show that the main portion of river sediment trapped in dam reservoir that will be caused dam reservoir utilize age decrease.

Organic byproducts with the lowest content of heavy metals, without organic and industrial pollutants are as an alternative to mineral and organic fertilizers for agriculture. The final residue of sugarcane agro-industry (Vinasse) is among the residues that are produced in large amounts in Iran. Vinasse is rich in organic matter and can be considered for improving soil fertility and to reducing runoff and soil loss. Nonetheless, there has been less attention to determine the appropriate amount of Vinasse in soil and water resources management. According to the references, the amount of Vinasse more than 100 ton ha-1 will cause pollution of surface and groundwater. The aim of this paper is to review the use of the Vinasse and the appropriate amounts in soil and water resources management in available references and documents.

Careful monitoring of spatial and temporal change of ground level complications to understand the relationships and interactions between human and natural phenomena in order to better decision-making is very important. Remote sensing data are the primary sources that are widely have been used to monitor changes in recent decades. In this study, the land cover changes using three time satellite images i.e. 1988, 2001 and 2010 in Ilam Arkavaz watershed has been studied. Therefore, each of the images were classified using maximum likelihood method. The main identified classes are residential, agricultural, garden, forest, pasture and land without vegetative cover. Area of this land use classes for each year is determined and compared. Analysis of temporal changes of images shows the percentage changes over the 22 years studied in land use classes were as Residential 56.03, agriculture 24.85, garden 65.93, forest 27.4, pasture - 15.3 and no vegetation cover 27.45. The results indicate that the forest and pasture areas of have been facing with reducing the area and the annual rate of decline forest area in this watershed is 0.97 % that is higher than the global average (0.2 %). This situation indicates a worrying decline in forest cover in the region.

Nowadays, the soil erosion and its associated impacts, is one of the most important environmental problems. The forest road system is a primary area of concern related to runoff and sediment production by removing of tree cover and forest floor cover. However, there is a lack of information documenting the effectiveness of different levels of land cover in reducing sediment loads from back slope of forest road systems. The purpose of this study was the better understanding of vegetation role in runoff and soil loss control in forest roads using rainfall simulator at Azadshahr Kohmian. Therefore, four levels of landcover including 0-20%, 20-40%, 40-60% and > 60%, were used to assess forest road cutslopes in control runoff and sediment by rainfall similator at an intensity of 80 mm h-1 for 30 min. The results indicated that, the first and four classes had maximum and minimum amount of runoff and sediment yield, respectively. The amount of and less effect on with the rates of in control runoff and sediment in cut slopes of forest road by using rainfall simulation at an intensity of 80 mm h - 1 for 30 min. The results showed that different landcover classes resulted in runoff volume and sediment yield ranging from 4.37 lit to 28.35 lit and 6.29 gr to 28.35 gr, respectively. The lowest sediment yield rate and runoff volume were found on the fourth class with 6.29 gr and 4.37 lit, respectively. Moreover, runoff initiation threshold were shown to be a bivariate function of land cover percentage. Runoff initiation threshold was increased from 29 s to 53 s from first class to fourth class, respectively. The results indicated that sediment rates and runoff volumes were significantly influenced by landcover percentage.

Estimation of runoff resulted from precipitation is the basis of studies in many plans of development and utilization of water resource. Therefore, its measurement and calculation always has plenty problems due to the environmental limitations. Consequently, considering the importance of output runoff and flood volume estimation in watersheds to advance integrated watershed management of Iran, in this study, it has been attempted to implement nine empirical methods of runoff estimation in Banadak Sadat watershed. The achieved results are evaluated by the measured runoff at a hydrometric station located at the watershed outlet, using paired t-test, MD, BIAS, RE and RMSE tests. Then, the best model was selected to estimate runoff elevation having the maximum accuracy and efficiency in the studied watershed. After preparation of the required maps using GIS software and statistical tests implementation by SPSS software, the results showed that LACEY method was determined as the most appropriate empirical method for runoff estimation in the studied area, with MD, BIAS, RE and RMSE values by 0.016, 0.007, 4.36 , 0.026 respectively, and also no significant difference with the observed data at 95% confidence level, runoff elevation by 1.53 cm, runoff volume by 2.29 million m3, and runoff coefficient by 18.79%. Then, the sensitivity analysis was conducted using Excel software for LACEY model to determine the most effective reaches. According to the achieved results, the parameter F/Z has the maximum impact on the model output at reaches 6-8, 8-10 and 18-20.

One of the major issues in the construction of drainage structures should be protected in proportion with the river type. The design flow is based on the useful life period and also takes risks plays a very important role in selecting the location and type of structures and its design, ultimately. In this study, the spatial distribution of watershed management structures based on river order in 13 the study watershed is located in the province of Khorasan. Results expressed that in useful 5 year, With an acceptable hazard risk of 25% for straw dam and Rocky dam structures, in useful 10 year with hazard risk of 20% for the gabion, in useful 15 year with hazard risk of 15% for the cement dams and in useful 20 year with hazard risk of 10% for earth dams Based on the analytic hierarchy process had the highest scores. While The rate of return on plan acceptable straw dam structures Rocky dam and gabion structure to the 2x and for cement dams and earth dams 4x values is also used in the design is¬ implemented.

In rangeland watersheds, drought and salinity are the two preventive factors for production. So one of the obstacles to the development of plants that is salinity and drought during seed germination. in this study we evaluated the effects of salinity stress on Helichrysum globiferom and Helichrysum aucheri germination properties based on a In the form of a factorial experimental design with four replications and four salinity levels (0-50-100-150 mM sodium chloride) in seed Ecology laboratory of Sari Natural Resource Faculty. Seeds of two species were collected of Qushchy pastures in 70 kilometers of the old road of Urmia-Karabakh. Results showed that salinity stress had a significant reducer effect on percentage and speed of germination, growth of root and shoot length in two Species. Amount of reduction in the total in all traits species of Helichrysum globiferom species of Helichrysum aucheri. The amount of this reduction in all traits in Helichrysum globiferom was less than Helichrysum aucheri species. The ratio of Root to shoot length (allometric coefficient) also was the highest in Helichrysum globiferom. So we conclude that this species is more resistant than other species. So the highest decrease in both species was observed in germination percentage, germination speed, and root, shoot and plant length, in treatment 150 mM.