نشریه علوم و فنون منابع طبیعی
سال چهارم شماره 4 (زمستان 1388)

The optimal exploitation of water from a reservoir requires a comprehensive knowledge of future availability of water resources. In this case the amount of water that will be available in the future is important. Also, we need to examine the flows at the dam from a short-term perspective. The main aim of the shortterm estimation of the runoff is to evaluate the risk of floods. This is necessary to avoid overflowing and to minimize damage. In order to facilitate forecasting of the water resources, many different techniques have been developed through the years.
In this paper, using monthly data (since 1957 to 2003) obtained from Hydrometric station at Shaloo bridge (upstream of Shahid Abaspour reservoir), the Auto Regressive Integrated Moving Average (ARIMA) model and artificial neural networks (ANNs), prediction of monthly mean flow to shahid Abaspour reservoir was accomplished. On the basis of comparison of the results of the models with measured data and computation of standard deviation, variation coefficient, sum of square error, root mean square error and correlation coefficient of the results, the performance of ARIMA(0,1,1)´(1,1,1) model shows an improvement in comparison with the ANNs model.

Management of riparian zone vegetation is important because of its roles such as the increas of water quality, margin structure stabilization , suction and reservation of water, flood control, stream stabilization, wildlife habitat providing, recreational values, soil protection and decreas of loss of agriculture productions, protection of landscape and providing research site. Aras riparian zone is destroyed because of great vegetation losses. Thus assumption of proper design management methode is important. Analytical Hierarchy Process (AHP) was used for selection of different management methods in riparian natural vegetations. Results showed that the environmental criteria have the highest value (0.494), whereas social criteria are low from value point of view (0.093). Plantation using native species can be one of the objectives from environmental, politico- security and social viewpoints.

The nomination of california bearing ratio estimate in the estimation of forest machines traffic is one of the most basic variables in the planning of forest harvesting. In a forest harvesting planning, accessing to these variables is important and we have diverse methods to estimate that. Accordingly, in this project we use three diverse methods in california bearing ratio estimate: results of CBR test, using penetrometer for CBR evaluation and CBR classification in USCS system as a testifier for selecting the best way for CBR estimate. We conducted this project in parcel 22 of series 7 in Haraz watershed (Amol, Mazandaran, Iran) according to 5 groups of soil in FAO classification with 15 samples in the randomized complete-block and LSD test with %99 confident level. The results show that there are no significant differences between testbased CBR and the testifier. However, the results from CBR estimate with penetrometer and testifier in soil groups including sand and coarse texture loam show that there is no significant difference between those too; but in silt, fine texture loam and clay group one can witness significant differences.

This study was carried out to determination of withdrawal strength on wood dowel joint. Dowels were obtained from Hornbeam (carpinus betulus), which their diameter and length were 10 and 80 mm, respectively. T form joints were made from blocks of Beech (Fagus oreintalis). Samples were conditioned to 10 and 15% moisture content. Effects of joint plane (tangential or radial) and diameter of dowel embedment size (similar and 0.5 mm less than diameter of dowel) and conditioned moisture content (10 and 15 %) were investigated. Results indicated that in 15% conditioned moisture content withdrawal strength insensibly reduced. Also diameter of embedment has strongly affected on withdrawal strength as strength increased in 0.5 mm less than diameter of dowel. Plane of joint has significantly affected on withdrawal strength too.

The Samples of bagasse were collected from depithing bagasse (Wet method) from Pars pulp and paper Mill. The average fiber length, cell wall diameter and thickness measured were 1.596 mm, 20.961 and 9.719 μm respectively. The chemical components of bagasse including cellulose, lignin, ash and extractive were measured as 55.75%, 20.5%, 1.85% and 3.25% respectively. The optimum conditions of pulping regarding pulp yield (74.95%) were 20% Na2O load, on the basis of dry bagasse. The pulping temperature was 170ºC and temperature residence time was 30min. Pulp refining was carried out with PFI revolutions of 2600 and 5500 RPM up to freeness 345 and 433ml CSF respectively. Statistical analysis showed that mechanical properties of hand sheets with basis weight 127gr/m2 NSSC pulp made from bagasse with freeness 345 and 433ml CSF are better than mixed hardwood NSSC pulp.

In this study, thermal analysis of biocomposites made of lignocellulosic fillers and polypropylene was investigated. to this end, Beech flour and wheat straw selected and separately mixed with polypropylene with different filler loading 0, 10, 20, 25 and 30 weight percent. Then the samples were manufactured with injection molding method. For thermal analysis of samples thermogravimetric analysis were used. Result showed that thermal stability of pure polypropylene is higher than lignocellulosic components and the lignocellulosic components decomposed thermally at temperature of 150-450Cú. Also, between two types of natural components, the beech flour had higher thermal stability and lower ash content than wheat straw. With increase of component loading, the thermal stability decreased and the ash content increased. Also, degradation temperature of the composites occurred between lignocellulosic fillers and polypropylene. This result clearly showed that the low thermal stability of the lignocellulosic fillers was compensated by matrix polymer. The composites includeing beech flour had higher thermal stability and lower ash in comparison with the composites including wheat straw.

In this study hybrid and non hybrid composites of lignocellulosic materials / polypropylene were mixed in an internal mixer at the five levels of 0 – 100, 25 – 75, 50 – 50, 75 – 25, 100 – 0% which consisted of 30% kenaf fiber / wood flour in weight as well as 3% maleic anhydride as coupling agent and 1% estearic acid as lubricant. The standard samples were prepared by the injection molding. Tensile and flexural properties (strength, modulus and elongation at break), unnotched impact strength, and water absorption were investigated as a function of lignocellulosic materials. Non hybrid composites of kenaf fiber and hybrid composites that consists of higher amount of kenaf fiber show better physical and mechanical properties. scanning electron microscopy (SEM) micrographs of composites show a continuous and homogenous texture by the application of 3% coupling agent which result in a decrease in the vision of kenaf fiber and wood flour out of the polymer texture and a better bond between fibers and polymer. Micrographs confirm the results of the physical and mechanical tests.

In this research, some chips of kiwi residues (Actinidia Spp.) from the west of mazandaran in north of Iran were randomly chosen. The samples were prepared to measure fiber biometrical, physical and anatomical properties by using franklin and ASTM standard test methods respectively. The results showed that kiwi residues had semi-ring porous wood, and group vessels with spiral thickening. The parenchymas were longitudinal and axial. There were a lot of rays in cross-section. The average of the fiber diameter, ray thickness, fiber length, runkel coefficient, dry density, basic density, shrinkage and porosity were 172 m , 17.6 m , 1371m , 116.6, 0.668gr/cm3, 0.564 gr/cm3,15.7 % and 55.1% percent, respectively. The results indicated that kiwi residues properties were as suitable as the hard woods. The results also pointed out that the wood from kiwi residues can replace some or all of the raw material for production of pulp and paper, fiber board , particle board, and other wood composition boards in the wood and paper industries.

Acacia sp (Subfamily of Mimosidea), a fast growing and drought-resistent species is suitable for agro forestry. In this research, in vitro seed germination of Acacia albida and Acacia salicina using various concentrations of TDZ hormone were surveyed. At first, after washing with water, collective seeds were soaked in concentrated HCL. After being sterilized with Hgcl2 0/5%. seeds were cultured in N6 medium supplemented with various amounts of TDZ hormones, 0/1μm,1μm,10μm. Analysis of variance showed that there are statistically significant differences in using various treatments (P>%5). The result of duncan comparison mean (P>%5) suggested that use of N6 medium supplemented with 1μm of TDZ is more suitable. The final results of in vitro seed culture of acacia sp from this survey indicated that propagation of Acacia albida has better performance using TDZ hormone. Thus, using concentrated HCL for sterilizing and acting 1μm of TDZ hormone in N6 cultured medium would be qualified for future experiments. More than 90 percent of cultured seeds sprouted in two weeks and were ready to be transferred to pot after 6 weeks.

Due to role that plays in determining rangeland capacity, production has been used in most assessment studies of rangeland. Clipping and weighing are the most precise and prevalent methods to estimate production, for which other methods have been replaced because it is time consuming and expensive. Estimating of production by area and diameter of canopy cover and volume and height of shrub is one of the appropriate methods to estimate production. The mentioned methods were used in about 50 bases of Atriplex lentiformis of different ages in. Chaparghoimeh, Ghonbad Kavoos. For each base we measured area, small and large diameter of canopy cover and volume and height. Result of this study shows that there is a suitable linear relationship between real weight, area and diameter of canopy cover and volume and estimation weight. Real weight has the highest correlation coefficient with area of canopy cover (R2 = 74%). But the real weight has the lowest correlation coefficient with estimated height (R2=42%).