Year:2005 | Volume:18 | Issue:2 (67 IN NATURAL RESOURCES)|Papers Count:13

A karyological study of six taxa (eight populations) of the genus Artemisia L. from different geographic origins in west Azarbaijan province is presented. The work deals with chromosome number and their morphometry. We found the two usual basic numbers in the genus: x=9, the most common one (in two diploid and three tetraploid populations) and x=8 (in three diploid populations).Through ocular micrometry, five metaphase cells were studied from each population for several karyotype parameters, including long and short arm length. Using several estimating formula, karyotype asymmetry of the populations were investigated. Detailed karyotype analyses allowed us to group the different populations to investigate their relationship and evolutionary trends.

Wave reflection is one of the important parameters in design of a marine wall. Higher amount of reflection from a marine wall increases the wave height of wall and therefore the cost of the project. To reduce the wave reflection from a marine wall, special shapes of the wall facing should be used. One of the most efficient types, which seriously dissipates.wave energy and reduces the wave reflection, is caisson wall. This paper evaluates the wave reflection coefficient from caisson walls with different porosity (different dimensions and layout for caisson blocks). This study was done by using some experimental tests on a small-scale model wall. The results from the tests clearly show a relationship between wave reflection coefficient and the wall porosity and the wave parameters.

Descriptive mangrove plants structure (zonation) is one of the sustainable utilization of ecological management tools in coastal plants formation for the determination of Avicannia marina (Harra) forest structure in Harra biosphere reserve of Persian Gulf, Hormozgan Provice coastal regions, using line transect block-random design and quadrate plot random-systematic design. By the formation of 68 sampling plots parameters of 421 individual Harra trees were considered for statistical use. Mangrove vegetation in this region extending in an area of 9206 hectares with average individul's density of 859 trees per hectare (tr./hect.) having an estimated average height of 261.1 com and average trunk diameter from soil intersection of 17.8 cm. Crown average height and diameter of these trees were 220.9 and 230.1 cm respectively with existing average estimated aerial breathing roots number of 243.8/ m2 of substratum with an average length 13.4 cm. Average number of shed leaves for the same extension of substratum is estimated at 51.6 in Spring and 107.5 leaves in Autumn; seasons with significance difference of foliage between seasons. The average area of each individual leaves shed in both season being at 7.4 to 8.2 cm2 were not significantly different. Statistical analysis in this plantations showed that mangrove communities of this region cannot be segregated into independent integrates and they can be regarded as homogenous cover stand. Statistical association of considered parameters showed that by using regression line equations of crown area extend that is estimated aerial photography can be used to estimate other alternative parameters of trees within this region.

This study has done to determine the origin of dust storm and spreading of dust using satellite image processing. Since dust storms occur in large area and can transport a lot of dusts in long distances, large-scale repeatable images were needed. Besides the above-mentioned specification, the MODIS sensor from TERRA satellite receives long wavelengths of electromagnetic, which can be used to meet the purposes of this study. Five images of MODIS taken in 2001 were used in this project to meet the above purposes. An image of Landsat taken in 2001 was also used to prepare NDVL The measurements on the images of dust storm showed that the directions of dominant winds in Sistan's dust storm are between 339 to 346 degrees. These directions coincided with the directions of erosive winds in Zabol synoptic meteorological station. Visual interpretation on the origin and the storm ways, of dust storm showed that the dust storm starts over Hamoon Sabory Lake, and long passageways with heavy dust are separated from light dust, and to continue owards Iran, Afghanistan and Pakistan. These passageways seem like cones the head of which is at the origin and the bases towards the opposite direction. On the other hand, the extracted Nonnalized Difference Vegetation Index (NDVI) with its high values (0.24) of it was showed condensed vegetation in southern shores area of Sabory Lake. The comparison between the spectral signature of samples with heavy and light dust showed that, it had a little variation with each other. But afterwards, the passageways with heavy and light dust were formed.

Nowadays, increase in population and their needs to food and enough primary row materials, cause in degradation of natural resources in most of the countries in the world such as Iran, that due to geographic and climate conditions is different. Therefore suitable utilization of water resources especially floodwater can play important role in reduction of degradation and helping to food supply and improving environmental conditions. This paper is attempting to evaluate the impacts of floodwater spreading on changes of ground covers (vegetation, litter and bare soil) and standing crop production in a flood spreading area in Sohrain-Gharecharian plain of Zanjan. This plain is located in northwest of Zanjan and included rainfed, follow and released area. For these purposes, the data of diverted floodwater to the experimental area were collected during five hydrological years from October 1998 to June 2003. In order to evaluate the ground cover changes in four sites in spreading area, totally 16 permanent transects (14 in spreading area and 2 as control) were established. Then during a five-years period (1999 - 2003), by Line Intercept Method, the percentage of canopy cover of vegetation, litter and bare soil was noted. Also, for evaluating the standing crop production, 50 plats of 3x3 m (39 in floodwater spreading area and 11 in control area) were established and the standing crop of 1m2 fromeach of them were randomly cut and weighted each year. The results showed that the mean canopy cover in the spreading area increased from 22.22 to 56.18 %. The mean bare soil cover also decreased from 56.18 to 33.4 % during study period. The standing crop production in the last year increased 315 % related to first year and 208 % related to control site. Data analyzing by T-Test method showed that the differences of vegetation cover in 2 sites of spreading area were significant at 5 % level, and one site at 1% relate to control site. In totally, The differences of mean vegetation cover in spreading area with control site were significant at 1% level. For bare soil three sites had significant differences with control site at 1% level. For the production, the statistical analyzing showed that in the two first years, the changes of standing crop production was not significant related to control, but in last three years these differences became significant at 5 and 1 % level.

Flood spreading is one of the techniques to supply of water in the arid and semi arid regions in order to use of flash floods. Soil properties can influence floodwater quality and have an important role on the success of flood spreading systems. Because developing of flood-spreading schemes in the unsuitable areas from viewpoint of the soil and flood qualities may lead to some differences in soil properties in such areas. So, to find out the suitable methods to inhibit of soil degradation, it is needed to study of the soil physico-chemical characteristics of flood spreading systems. In this research, some soil qualities of Poldasht flood spreading station were studied during 4 years. The treatments were:Control; without flood spreading and seedling.Flood spreading with seedling.Flood spreading without seedling Some soil properties that in this research measured and analyzed were included of infiltration rate, soil texture fractions, pH, EC, TNV, soluble Ca, Mg2+ and Na+, SP%, OC% and Bulk Density. The means of measures were compared using LSD (Lowest Significant Difference) test. The results showed there are significant differences among some soil properties during 4 years of examinations. In comparison with the first year, some parameters such as EC, SP%, OC% and clay percent were increased whereas pH, Sand and Infiltration rate decreased. This means that flood spreading has had some positive and negative effects on the soil properties in Poldasht flood spreading station but the rate and trend of differences are very slow. So it is expected there will some difficulties in the future due to the differing in soil texture, decreasing of infiltration rate and increasing of soil salinity.

Desert is the biggest bioclimatic area in the world. Saxaoul (Haloxylon spp) is one of the most important stabilizing of sand dunes for biological combating desertification. For improving and development of Saxaoullands, 40 genotypes of 3 Saxaoul species (Haoxylon persicum, H. aphyllum, H. ammodendron) were collected from different areas of Iran and planted in a replicated experiment. Several characters such as height, crown cover, trunk perimeter, branch height, branch number, powdery mildew intensity and vigority were investigated. This research was carried out in Bajestan desert plants research station from 1998-2002. The results showed, the Largest crown cover, the biggest trunk perimeter and the largest branch belong to Haoxylon persicum and H. aphyllum and the lowest powdery mildew intensity and vigority belong to H. ammodendron. Powdery mildew on H. aphyllum was more intensive than that on H. persicum. Vigority of H. persicum was better than that of H. aphyllum. There was a significant difference between Haoxylon persicum, H. aphyllum, and H. ammodendron for branch number.

The Hashtad-Pahlu region with an area of 3000 hectars is located at SW of Khorramabad, the lowest and the highest of its height are 1000 and 2800 meters. Flora of this region includes 205 plant species that belong to 155 genera and 49 families, the important families are Labiatae, Compositae, Graminae and Liliaceae with 10.73%, 9.2%, 8.9% and 7.8% respectively. Life forms of the plant species of Hashtad - pahlu area include: The rophytes 29.26%, Geophytes 38/52%, Chamaephytes 16.58%, Hemichryptophytes 6.84% and Phanerophytes 8.78% form the view point regional elements plants of this region include: 69.27% lrano- Touranean, 24.39% Mediterranean and Irano-Touranean 1.95% Europe - Siberean and Irano-Touranean and 4.39% Cosmopolitan.

Proper stream network mapping is highly needed for any hydrological studies particularly for automatic flow routing in GIS based raster models. Generally, one of the disadvantages of making use of digitized stream network, based on topographic maps is incompatibility of stream features with flow direction vectors. In an uncertainty condition, making use of this stream network will terminate routing program before normal ending. An algorithm was designed, making use of Avenue program in Arcview GIS. Designing this algorithm was based on D8 method, which is one of the pixel to- pixel flow conduction methods. Points lying on digitized stream network can get elevation in a vector domain. Then, these points can be used in determining stream flows, which produces new stream network of catchments. The new generated stream network, in spite of having vector property, exactly coincides with flow direction patterns. One of the most important specifications of this algorithm is reallocation of stream network without generating extra features.

Recent developments in using unprotected roller compacted concrete (RCC) in hydraulic structures necessitates a trough investigation of the parameters affecting its abrasion resistance, particularly within the spillways. This paper covers deterministic aspects of RCC's abrasion resistance by means of the more influencing parameters such as specimens age, cement content and aggregates gradation, specific surface, compactness - which could be defined by a representative factor that can be called mean hydraulic radius. To ease laboratory observation on abrasion/erosion phenomena and for the sake of generalization, the water-sand blasting technique was employed in this investigation. Findings ofa statistical analysis of the experimental data indicate that: A- RCC's abrasion resistance is a direct function of the compressive strength; B- by increasing aggregates' mean hydraulic radius, abrasion resistance can be improved; C- the higher the cement content and age of specimens, the better will be abrasion resistance of RCC.

The research studies in Iran have shown that the MPSIAC model for estimating erosion and sediment yield in watershed level, is one of the most common empirical models which has been widespreadly used in comparison to the other models on ungauged watersheds of Iran. A reason for use of this model is only because of the accuracy of the obtained result. In this study, erosion and sediment yield rates was estimated by MPSIAC model using geographic information system (GIS) in the Nojian watershed basin. In order to run the model, the watershed area was divided to 527 homogenous units and the nine factors used in model, were assist in each unit. The results of this study indicate that amount of sediment yield in the study area is about 489372 Tn y-1. Considering the amount of the observed sediment yield of the watershed, which is about 812410 Tn y-1, the amount of estimated sediment yield is significantly differs by 323038 Tn y-1. The observed difference can not consider as this mean that the model should or should not be employed in watershed projects. It seems that there must be a rational reason (s) for difference between the observed and estimated amount of sediment yield. The results of the evaluation on the observed difference were shown that it should has the root in structure of the model as well as its related tables for rating and weighting of the factors included in the model. Because it appears that, the tables of the model used for rating and weighting of the included factors are not complete and can not be used in areas were the characteristics of given watershed are not similar to the development area of the model. It can be concluded that in order to accept or reject the result of the sediment yield estimation using the MPSIAC model with high confidence, the model first should be calibrated based on the existing condition of the Iran's watershed.