IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2004 | Volume:57 | Issue:2|Papers Count:18

This research deals with a new method of harmonic application of environmental data from research area as well as input functions, (i.e. rainfall and floods as operating agents in basin system), to obtain a model for estimation of flooding potential in basins. Serious consideration was paid to understand relations between environmental factors and effect of input resources such as rainfall. In this relation, applied model made it possible to determine area with iso flooding potential in the region under consideration. Although using mathematical and statistical methods can answer many questions in this field, but what makes it different is that, environmental factors, their complicated relations along with their contribution to flood initiation in path with storms are treated from different points of view. Analysis of multiple environmental data led to moving from pure statistical definition of flood phenomenon to quantitative-and qualitative description of flood process to obtain special indexes according to available standards. Obtained model could be used to predict response of iso potential sites to different storms.I-Results and achievements of model can be further described as follows:-Precise understanding of operation system's response to different systems in micro conditions (Iso potential units) as well as macro conditions (hydrologic units) as a new method in understanding of flood initiation process.- Determination of CN could be possible with introducing of mathematical equations without referring to related tables and graphs.- Introducing four equations in relation to vegetation cover and land use as a direct parameter in estimation of CN in different hydrologic soil conditions in research area.- Introducing of four equations in relation to slope as an independent variable as related to vegetation cover on four different hydrologic conditions in research area.- Analysis of soils curve numbers in four different conditions on 855 Iso flood potential units.- Flood hydrograph simulation on hydrologic units and Saghez Chay basin.2- Applied results of model: - development and generalization of SCS method for its improvement as well as speed up of CN formation in four different soil conditions.- Strategic results of this research could be applied to improve sustainable management of water resources for evaluation of environmental resource as well as determination of flood potential at different times and conditions.  

Estimation of rainfall is indispensable in many natural resources and agricultural studies. There are several methods of estimating rainfall among which interpolation is helpful in this regard. In most cases, a method is selected and estimation is then made with unknown precision. In this study, 3 methods were used to estimate annual rainfall. These methods were: Thin Plate Smoothing Splines (TPSS), with and without covariable, Weighted Moving Average (WMA) and Kriging (ordinary, Cokriging, Log kriging). The data in 167 stations from south east of Iran with 22 years of record were used in this study. Elevation was used as covariable and its correlation with rainfall evaluated. Because of size of the area and dispersing stations, the correlation coefficient was low and unacceptable for all stations. Therefore, the study area was divided into subcatchments, based on watershed catchments. In cases where few stations existed in the catchment or regression coefficient (between elevation and rainfall) for two stations was the same, those subcatchments were combined. Finally, 3 units of subcatchment were obtained. Regression coefficient between rainfall and elevation was low in one of the subcatchments (R=0.12) while in the other two subcatchments was higher (0.7 and 0.8). The results show that regression coefficient (between rainfall and elevation) must be grater than 0.6 to improve interpolation accuracy when using elevation as covariable. The results also show that TPSS method with elevation as covariable is the most precise method in estimating annual rainfall (MAE=13-38 mm). Kriging (MAE= 29-50 mm) and WMA methods (26-57 mm) stood in second and third order, respectively.

Wind erosion is one of the main and important natural phenomena in arid and hyper-arid regions. Wind erosion is due to blow of erosive wind on dry, soft and erodible soil. Soil particles are transported in three mechanisms: creeping, saltation and suspension. Wind erosion causes serious damage to the environment. In this research, the investigators try to recognize soil physical and chemical properties as related to threshold velocity. Threshold velocity was measured in a natural soil surface condition by a portable wind tunnel (wind erosion meter). Soil samples were air dried. Desert pavement, mean diameter of soil particles, electrical conductivity, sodium adsorption rate, gypsum, organic matter and lime were determined. The relationship between desert pavement and mean diameter of soil particles is more significant than the relationship of other factors to threshold velocity. The mathematical function detected is presented in two models, on the basis of main physical properties and main physico-chemical properties.

To find the effect of important site variables on quantitative and qualitative changes in natural beech stands in Asalem, method of principle component analysis (PCA) was used. In this area ten sites consisting of 242 sample plots were investigated. Based upon and by employing Braun-Blanquet combined scale and TWINSPAN classification, 8 vegetation groups were distinguished. After determining vegetation groups, the groups were analyzed using principle component analysis (PCA). Twenty five variables in the 8 vegetation groups including: features of forest stand, physiographic factors and some soil characteristics were analyzed. The results showed that organic matter, nitrogen (in second and sixth groups) and altitude factor (in fifth and eighth groups) were important indices that affect the variations between groups. The features of the first axis were the most important factors on variations between groups. The obtained results also showed that the studied variations on the right of first axis were indices of productivity and the mentioned axis factors may affect the variations between groups. Finally, the results indicated that the most variations were at the sixth group which had the most egen vector and was situated on the productivity axis. Therefore, site variations on this axis exerted the most effect on the quantitative and qualitative characteristics of the sixth group. All studied sample plots in this group were situated toward north at 1000-1200 above sea level. The sites situated in this group consisted of deep soil, more moisture and high silt. The forest stands that were situated in this group enjoyed a more suitable condition as compared to other groups.

The objective in this study was to find out the effect of average groundwater depth on the qualitative and quantitative characteristics of bald cypress (Taxodium distichum) at the margin of Lapoo marshlands, in a northern province of Iran. The experimental design was a randomized complete block one with four treatments and four replications, conducted within twelve years. Differences between the average residual saplings (92, 65, 21, 8 Percent) and various degrees of average quality of saplings (best, suitable, weak, unsuitable) in relationship to treatments (average depth of ground water) were significant. Differences between the average of the diameter of collar (192.5, 134.8, 34.7, 19.2cm), diameter at breast height (88.9, 61.4, 12.4, 7.2cm) and height of saplings (490.4, 353.4, 118.1, 91.5 cm) in relationship with treatments (average depth of ground water) were significant. Comparison between the means of quantitative characteristics as well as various quality degrees (best, suitable, weak and not suitable) of bald cypress (Taxodium distichum) indicated, best place for planting is in those localities in which the average depth of ground water is 62 centimeters (minimun+23 cm, maximum- 149.12cm). The other treatments namely average groundwater depth of 85, 97 and 124cm were not suitable for planting Taxodium distichum.

A 3x3 factorial experiment was conducted for 60 days to determine the response of Indian white shrimp (Fenneropenaus indicus, H. Milne Edwardes) juvenile to diets containing various energy levels. Three semi-purified and isonitrogenic diets containing three levels of energy (3500, 3800 and 4100kcal/kg) with a constant protein content of 40 % were formulated, then prepared in this trial. Each diet was evaluated in three levels of salinity (25, 35 and 45 ppt). So the study was conducted with 9 treatments in triplicate random groups of20 shrimp (average weight of 3.22±0.19 g) per each 300-litre tank. Each tank was filled with 200 litres of water 50 percent of which was exchanged every day. The shrimp were fed their respective diets on a saturation basis with the feed divided into three parts to be fed at 08:00,14:00 and 20:00 hrs. daily.The results of the study indicated: with increase in energy and decrease in salinity, growth performances improved. Diet containing 4100kcal/kg energy and salinity of 25 ppt (4100 : 25) in view of weight gain, SGR,FCR,PER,NPU and yeild was significantly (p<0.05) better than other energy and salinity levels. Furthermore, the study showed that 25 ppt salinity was significantly (p<0.05) better than other salinities for this shrimp culture.Carcass analysis of shrimp (except for energy and lipid) was not significantly affected (p>0.05) by increasing levels of dietary energy. Increasing lipid and energy content tended to have an effect on carcass analysis proportional to the increase in dietary lipid and energy. Salinity interaction did have a significant effect (p>0.05) on an approximate analysis of shrimp carcass.

Waste is an inevitable final product in human societies. Life and environmental risks resulting from inadequate management of solid waste are a main problem in a country. However, to manage and analyze different spatial data, GIS is a useful tool that in the short run and with a little cost can fulfill the purpose with adequate accuracy. In this research, it is intended to determine the best range for prescribed factors (as a model) and then to find and select the best sites for solid waste disposal on a map.

Economic progress and development of a country depends to a large extent on the appropriate operation of its different industries. Pulp and paper industry producing a product with high added value has an important role in this development. Different ways are available for operation evaluation of a productive unit. One is the assessment of productivity which refers to the way the production factors are used to make output. This study was performed in Iran Wood and Paper Industry (Chuka) which is one of the largest paper factories with a capacity of 150000 tons of paper – per year. The index approach was used for the assessment of productivities and the study covered a period often years from 1991 to 2000. Different economic as well as physical productivity factors evaluated and then with use of correlation, regression and principal component analysis the relationship between production factors and total productivity were investigated. Finally a comparison of factory performance in best and worst conditions was detected and the reasons for decrease or increase in each productivity index are expressed and the ways by which productivity can be increased are presented.Total productivity in 1992 amounting to 1.032 constituted the lowest quantity while in1994 at 1.518 was the highest. The following are some of the factors affecting the total productivity: direct material productivity, chip productivity, capital productivity physical energy productivity as well as fix assets.  

In this research, the effect of Kraft lignin content, temperature and time of hot press on some physical and mechanical properties of wet process hardboard (S1S) made from mixed fibers of various species of Iran Fiber Company was studied. The values of 1) Kraft lignin, precipitated from Kraft black liquor, at three levels of 0, 5 and 10 percent (based on ovendried weight), 2) press temperature at two levels of 190 and 200 degrees centigrade and 3) press time at two levels of 8 and 10 minutes were selected. Measurements of physical and mechanical properties of produced boards, including density, water absorption and thickness swelling after 24 hours of soaking, modulus of rupture, internal bond and tensile strength parallel to the surface of boards were made according to ASTM D1037, and then the results were analyzed statistically. The results in this research have indicated that the best treatment for increasing dimensional stability is using Kraft lignin content of 10%, press temperature of 200 degrees centigrade and a press time of 10 minutes. As concerns mechanical properties, the use of Kraft lignin content of 10% without increasing temperature and press time resulted in desired bending properties, whereas use of Kraft lignin content of 5% along with increasing temperature and press time resulted in improvements in internal bond and tensile strength parallel to surface of boards.

The service life of railway impregnated cross-ties in Iran is much lower than indicated in the International Standards. In this connection, some researchers believe that the moisture content of the timbers is not optimal prior to the treatment process. Therefore, the present study was conducted to study three different MC levels (12, 23, and 51%) to compare creosote retention as well as its penetration in impregnated samples, using Bethel method. Results show that there is no significant difference between 12 and %23 (below FSP) Moisture levels. Therefore that would be enough to decrease the MC to about %23 to insure the timbers would be properly impregnated with creosote, that is, there is no need to season the timber to as low as %12 MC. This would facilitate and simplify treatment process as well as increase the service life of the impregnated timbers, including those used in railway cross-ties.

To make a primary investigation of lignin content variation as related to content of peroxidase enzyme in different seasons and in different sites, samples were taken in four regions, and during two seasons, of eucalyptus (Eucalyptus camaldulensis) trees. Qualitative and quantitative survey was done by employing PAGE and spectrophotometry methods. The Content of Klason lignin was determined using extractive free wood sawdust.The results show that peroxidase isoenzyme patterns change depending upon region and season. This can be speculated as a part of tree physiological change, preparing to resist against cold. It was also observed that there are differences among ecological regions as well as among trees in the same region. Based upon the genetics of the trees, lignin content in Khuzistan region decreases in winter and so does enzyme activity. Lignin content was directly related to branch diameter as well as enzyme activity.  

Sort-term effects (one grazing season) of rotation and continuous grazing systems as well as heavy, medium and light grazing intensities on standing crop and vigor of Bromus tomentellus Pasture was studied in Homand Abesard Range Research Station. The treatments in each system were analysed while taking in to account a randomized complete block design. A comparison of the two systems was made using t-test. Sangesari race sheep was employed as the grazer animal. One handred stands were sampled in each grazing intensity for parameters of standing crop and vigor. The results showed that the rotation of grazing system had more negative effects on the parameters. In both grazing systems, the parameters decreased when the grazing intensities were increased. The standing crop and vigor in treatments and control differed significantly. The variations in plant height and stalk were the same as variations in standing crop. Except for differences of heavy and medium treatments in continuous system, the differences in treatments of grazing intensities and control in both systems were significant.

The objective of this research is to survey the capability of ETM+ dedector s data in estimating vegetation cover and phytomass production in the semi arid rangeland of Hanna Research Station in Isfahan Province. Initially the percentage of total vegetation, grass, forb cover and phytomass were estimated using 450 plots (1 × 1m) in 45 randomly chosenclusters. Global Positioning System (OPS) was employed to determine and adjust the sampling unit positions in corresponding unit characters in the image. After georefrencing the Thematic Mapper Image, dated June 2001, by 1:25000 digital topographic maps (dgn), developed by National Cartographic Center with RMS error of less than 0.5 pixel size, the ordinary vegetation indexes and soil line vegetation indexes as well as hybrid bands were evaluated through HIS and SR methods. Then by vector layer of sampling clusters, the digital number of indexes as well as origin bands in each cluster was extracted. The results of simple linear regression analysis between indexes (as independent variable) and biophysical parameters (as dependent variable) through SPSS software show that there is a significant relation ship between vegetation indexes and biophysical parameters. According to these results, the fourth original band of ETM+ has the highest correlation coefficient (r = 0.66 and SE=4) with total vegetation cover.Likewise, ETM4 and VNIR2 indices with r= 0.56, SE=1.8 and 3.2 show highest relations with forb cover, while the fifth original band ofETM5 with r = 0.6 and SE=2.2 show the highest correlation with grass cover. As regards production the fourth band of fusion exhibits the highest r (0.52) with SE (6.3). According to the results in this research vegetation cover and production could be estimated through ETM4, VNIR2 index and HYB4.  

The most prevalent way of rangeland utilization in Iran is sheep and goat grazing. Rangeland utilization has been performed in 3 forms; nomadic, seminomadic and rural type. Each form affects rangelands in a particular way. Increase in sheep-farmer population and decrease in Farmer's income on the one hand and the poor conditions of the rangelands on the other hand have caused severe disturbances to the balance among livestock, rangelands and the beneficiaries. This has caused a shortage of forage on the rangelands, therefore, through force of circumstances the sheep farmers have to use other sources of forage. In order to improve the situation, the government considered a plan to settle the nomads in some suitable areas as from 1993. This plan aimed at persuading the nomads to settle in a permanent ecosystem to have their life conditions improved. One of the sites selected by the government for this purpose is a summer quarter named Bakan Plain located on the north of the Fars Province. A group of nomads including 4 tribes was persuaded by government to settle in this area (Planned Settlement). Two other groups of nomads, the volunteer setteleres (Unplanned Settlement) including 2 tribes, and the migrants including I tribe used to live in this area from many years ago. This research which was commenced in 2001 and ended in 2003 aimed at studying forage production and exploitation as well as a comparison of the three mentioned groups as regards their effects on the rangeland. Using the previous studies, field visits, filling up questionnaires, as well as interview with the nomads, the indices of production and exploitation of the rangeland were assessed. The obtained data were analyzed statistically using Excel and Spss softwares. The results showed that not only there is a significant difference in production and exploitation effects on rangeland for the 3 groups but also there is a significant difference among the tribes within each group. The results also showed that the condition of production and exploitation of the rangeland is better in the volunteered settler nomad ones than the other two groups; the migrants and the planned settlers. It seems this is due to decrease in number of livestock, supplementary feeding of the herds with crop remains as well as long duration of the volunteered settlement.

This research was conducted to study the phenological stages of four important range species in the Dehbid enclosure during three years from 1998 to 2001.Factors of seasonal variations, morphological differences and plant development stages were studied. The aim of the research was to determine the proper grazing time in rangelands based upon range readiness and to recommend the best grazing systems.The studies were conducted on three perennial grasses (Stipa barbata, Bromus tomentellus and Oryzopsis molinioides ) as well as one perennial forb (Onobrychis melanotricha). Nine individual plants of each species were selected. Growth development stages during a three years period (once every week at active growth stages and an extra time every month) were recorded. The climatic data, including daily air moisture and temperature, were also recorded. On the basis of phenological stages and ombero-thermique curves, the best grazing time for longevity as well as optimum seed harvesting time was determined.The results indicated that the growth period of Stipa barbata, Bromus tomentellus and Oryzopsis molinioides is longer than that of Onobrychis melanotricha. All four species have autumnal regrowth, if the environmental conditions such as moisture and temperature are favorable.