فهرست مطالب omid ghafarzadeh

The production of a coating agent based on the extracted lignin from black liquor of bagasse soda pulping was investigated. The crude lignin was modified via sulfomethylation method to increase its solubility. Both unmodified and sulfomethylated lignins were applied on the testliner papers with and without starch and physical, surface and mechanical properties of the coated testliners were evaluated. The viscosity of coated solution containing 100 percent of crude lignin was very low and similar as that of water. Addition of starch to coating solution resulted in increasing of the viscosity of formulation. Evaluation of hydrophobicity of coated testliners showed that compared to papers treated with unmodified lignin and starch, the papers treated with sulfomethylated lignin had significantly lower water absorption, wetting rate, absorption rate of water droplet, which resulted in hydrophobicity of papers. Colorimetric analyses showed a decrease in lightness (L*) of the coated testliners with only unmodified lignin compared with untreated control ones. In contrast, the lightness of testliners coated with sulfomethylated lignin was significantly improved and was almost as high as control samples and samples, which coated by the starch solution without lignins. Air permeability of the coated testliners with only lignin was significantly lower than that of lignin-starch coated samples. The results also showed that the tensile indices of samples coated with unmodified and modified lignins were significantly higher than that of control ones. The tensile index of testliners coated with starch-lignins solutions was almost near to that of samples treated with only starch solution.

The hydrological regime of a river is the main influencing factor on the dynamics of river ecosystem and damming operations have a significant impact on river flow discharge. Therefore, the main objective of this research was to investigate the combined effects of  changing climate variables and the Yamchi Dam construction on the discharge flow of the Balkhlu-Chai River in Ardebil using IHA Software 7.1 during the pre and after dam construction period (1973-2003) and (2004-2014). Toward this, the trend in the amounts of precipitation, temperature and evapotranspiration variables were evaluated using MAKESENS software. Then, the changes to 33 hydrological parameters and Range of Variability Approach (RVA) were firstly estimated. Subsequently, changes in the parameters of the flow rate in the periods before and after dam construction were investigated in the magnitude, duration, timing, frequency and rate of change categories. According to the results of trend analysis the precipitation had a significant decreasing trend, while, the temperature has been increased during the available time period. Based on the results, about 92% of the minimum flow discharge was attributed to that after the dam construction, while 25% of the maximum discharge belongs to this period, which indicates a decrease in the magnitude of discharge flow due to the dam construction and decreasing trend of rainfall. Also, the number of high flow pulses during the period of before dam construction was 38% higher than the period of after dam construction, while the number of low pulses in the period after dam construction was reduced by 60.7% compared to the period pre-dam construction. The value of Rise Rate index in the after-dam construction period is 0.11, but in the period before the dam construction is 0.3, which indicates a notable decrease in the mentioned indicator. Generally, based on the Magnitude group parameters, it can be concluded that the average amount of river flow during the period after the construction of the dam decreased by 52% compared with the period before the dam construction which lead to considerable environmental issue regarding the river ecosystem and flow condition. It should be noted that the variation in the hydrologic indicators is mainly influenced by the dam construction and also the change of climate variables has also been influential in this regard, and the separation of affecting factors need to be considered in further studies.

Sustaining environmental flows to preserve biodiversity of aquatic plant and animal species, as well as constancy of water for human communities, is essential in many river ecosystems. On the other hand, hydrological changes caused by the dam and its related environmental problems have provoked many concerns for hydrologists, ecologists and policymakers. Therefore, the main aim of this research was to study the rate of change in the Environmental Flow Components (EFCs) caused by the construction of Sabalan Dam in the Qarehsou River of Ardebil at stations of Arbabkandi and Dostbeiglou (before and after Dam) using IHA Software7.1 during the time period of 2005-2014. For this purpose, the values of 34 environmental flow parameters were estimated at each hydrometric station. Consequently, changes in the parameters of the environmental flow discharge were investigated in four groups of Extreme Low Flows, Low Flows (Base flow), High Flow pulses, and Floods events. The diagram below shows the parameters of minimum flow, peak flow and small flood. Based on the results, the frequency of Extreme Low Flows at the Dostbeiglou station had a 59% increase with respect to Arbabkandi station. On the other hand, the peak flow component showed more balanced nature in Dostbeiglou station after the dam, which can be related to the regulating effect of dam on high flow and balancing outflow in downstream reaches. The Peak flow, Duration, Timing and Frequency of small flood events had decreased in Dostbeiglu Station compared to the Arbabkandi with amount of 27, 78, 68 and 17 percent, respectively. Also, the peak and frequency of large floods had decreased at Dostbeiglu station with amount of 26 and 50%, compared with the observed flood events at the Arbabkandi station which located before the Sabalan dam.