نشریه مهندسی اکوسیستم بیابان
پیاپی 6 (بهار 1394)

Temperature is an element of climate that it has changed during the time and affected other parameters with changing itself. So we can account it in category of the most affect of the climate parameter. The purpose of this study was analyzed trend of annual and seasonal maximum temperature during the past decades in the Daryache-e-Namak basin. So, the data of 14 Climatology stations that located in the study area during of 1969-2008 has been used. At first, the series were measured with using Joiner test for determine normal and abnormal distribution of the data then their homogeneity was assessed with using Run test. For choosing measurement's models and analyzing of the series trend was used Tr parametric test, Man Kendall nonparametric test and for prediction of tendency changes was used Holt method and Least square. The results of this study show that there was increasing trend in the most of the stations in the study area. So in the annual period, 8 stations follow increasing trend. Increase of the maximum temperature in Damaneh is more severe than elsewhere.

In order to river flow forecasting in catchments area in during many years are invented different methods that their efficiency is confirmed. One of these simulation models is neural network that it can draw the existence of truth together with considerable attention. In this research in order to Discharge simulation is investigated meteorological parameters effects on Ghare Aghaj river flow. For this reason it is used monthly discharge, precipitation and temperature data of present stations with statistical period of 23 years, in during 1981 to 2003. The existing data divided into two groups of train and test after normalization and then they were tested with 5 different types and 9 models and by using from multi layer perceptron neural network together with error back propagation law and also LM and Gdx learning functions. The best network arrangement using from LM learning function was prepared in the case of 9-21-1 with correlation coefficient quantities 1 and 1 for train and test data orderly and for Gdx learning function was prepared in the case of 7-13-1 with correlation coefficient quantities of 0.94 and 0.96. The result represents the meteorological parameters effect like temperature and precipitation is clear on output flow and also exist a inconsiderable difference between simulated and observed quantities. Also neural network shows a better efficiency in river flow simulation by LM learning function.

Desertification means Land degradation in arid, dry sub-humid due to various factors such as climate change and human activity which is one of the considerable problems. Soil Salinity also is one of the main causes of desertification. One of the dynamic properties of soil is the soil salinity; this characteristic is one of the main problems in arid and semi-arid areas which much of the territory of Iran is in these areas. Khuzestan is one of the provinces where the salinity problem is considered as the main problem for farming. Especially the southern part of the province, where the land has a heavy texture and underground water level is high, but they have capability to get reclamation. This study investigated changes in soil salinity in the area of about 11869.207 hectares of land in Khuzestan province, satellite images Landsat relating to the years of 1973, 1990 and 2000 were geometrically corrected and then were used as the main data. Images in the form of maps and tables were presented in four periods after correction of classification in GIS systems. Generally the results show a significant increase in the vast of saline soils in 28 years.

This study was carried out to investigate the effect of crown canopy of Pistacia atlantica, Amygdalus scoparia and A. eburnea species on seed bank density (size). Ten individuals of each species were selected and one plot under and another plot outside of the crown canopy of each species were established. In each plot, soil sampling was done from 0-5 and 5-10 cm depths. The soil seeds were identified in green house study through Germination Method. General linear model was used to clarify the effect of crown of woody plant and soil sampling depth on seed bank density (size). The results showed that the density (size) of seed bank under crown canopy of P. atlantica was significantly higher than other two species. The density of seed bank in 0-5 cm depths was significantly higher than 5-10 cm in all three woody species. It can be concluded from the results that crown canopy of trees in dry rangelands can play an important role in soil seed bank reservation. Therefore, the conservation of individual trees in these areas has to be concerned by managers.

Soil erosion is one of the fundamental issues in the fields of environmental, natural resources and agriculture. Nowadays having knowledge on this topic and related issues have to be considered more and more. It is essential to use new methods instead of traditional methods in order to understand and apply more appropriate planning. The aim of this study is to study erodibility of Boir Ahmad province using soil erodibility factor (K) in relation to some of its effective properties using geostatistical techniques. In this study, 42 soil samples was studied at a depth of 0 to 30 cm with spatial distribution for determining the amounts of fine sand, clay, silt and organic matter, and finally soil erodibility factor. According to the results of spatial distribution of fine sand, clay and organic matter, variogram with Exponential Model and for of silt, Gaussian variogram Model and soil erodibility factor, linear variogram model were the most appropriate variograms. The results of comparing the methods showed that for mapping fine sand, clay and factor of erodibility ordinary kriging and for mapping organic matter and silt simple kriging are the best ones with the minimum error (RMSE). The obtained map showed that the lowest soil erodibility factor was 0.086 in the Northeast and 0.53 in the southwest of the study area. Results of the correlation between the properties affecting erodibility and the soil erodibility factor showed that there is a negative correlation between the organic matter and clay with the erodibility factor (R2=-0/64, P<0/01) and (R2=-0/97, P<0/01) respectively and There is a significant positive correlation between the amount of clay and silt with soil erodibility factor (R2=-0/73, P<0/01) and (R2=-0/38, P<0/05), respectively. The results show that the correlation is very high amounts of clay and clay with increasing soil aggregate stability is important for reducing erosion and organic matter increased with increasing aggregate stability and water permeability directly and indirectly has a significant role in reducing soil erosion in the study area.

An experiment was carried out to investigate the effect of progressing water deficit stress on leaf water relation parameters and compatible solutes at different phenological stages. Completely randomized design including four phenological stages (as drought stress treatments) was used. Each treatment had four replicates. Variables measured were osmotic potential (ΨS), relative water content (θL), total osmotic adjustment (TOA), proline and total soluble sugar (TSS) content. Data collected were analyzed using analysis of variance (ANOVA) at significance level of P<0.5%, followed by the Duncan multiple range test. The results obtained show that improving drought stress during phenological stages ΨS declined from -6.01 MPa (in FS) to -6.67 MPa (in SFS), respectively, for a decrease in θL of 20.24%. Coupled with improving water deficit stress, a 55.5% increase was observed in TOA. For both proline and TSS content, among phenological stages (concomitant with water deficit stress), the lowest and highest levels were obtained in VS and SFS, respectively.

Yazd – Ardakan Plain is located in the center of Iran. That most of the population in Yazd Province are concentrated in this plain. So Temporal and spatial study of Groundwater Quality is necessary. In this research, 30 wells with suitable distribution were investigated and quality zoning was done using simple kriging method analyzed for indexes of EC, TDS and SAR during 2002 -2010 statistical period. According to the obtained results in this research,, Groundwater Quality in Yazd – Ardakan Plain has been decreased from South West and West to North, North East and East. reason of for this subject is Neogene formations in the East and Salt Desert around SIAH KOH desert in the North And also the direction of groundwater flow to the outlet area in the north of the basin, which also helps. And reduce the quality of groundwater. Maximum average for indicators of EC, TDS and SAR were occurred in years of 2002, 2007 and 2002, respectively and Minimum average for indicators of EC, TDS and SAR were occurred in years of 2003, 2003 and 2009, respectively. It seems that the trend of the three indicators follows from groundwater fluctuation pattern and drought. The three studied parameters studied have upward between the years 2005 to 2007 Upward and then to have downward.

Lack of precipitation and it`s result water deficit is one of the most important problems in arid and semi-arid regions. Developing of (RWH) can be used as a method of increasing cultivation, play a significant role. (RWH) methods obviate water requirement and due to its properties can decrease flood risk and control sediments. In this article during a statistical analysis, determine effect of (RWH) methods to reduce flood and runoff in watersheds that have been implemented in their upstream Rainwater harvesting treatments this study were carried out the in 9 sub-catchment that all in Semi-arid and sub-humid climate in Isfahan province Watershed in terms of vegetation, soil and geology are almost homogeneous in terms of these conditions are the same period. Rain water harvesting treatments were carried out in all watersheds. Due to the variety of treatments, several hydrological response of runoff and flooding can be seen in each of the basins. Three types of treatment including pitting, planting on contours and terraces counter at this area is implemented And their effect on the amount of runoff and flood volume In a randomized complete block design with three replications of three treatments (for each region) were examined. Results show that, (RWH) methods affect on flood control and decrease runoff obviously. Duncan Test classifies different (RWH) treatments in 3 statistical groups.

Infiltration of water into the soil accounts as a phenomenon in which most of researchers and scientists are interested so it acts a prominent role in the water cycling. Owing to temporal and spatial variation of infiltration, measuring of it in a direct way requires a long time and high cost. Thus, using a method for measuring the soil infiltration in an indirect way instead of direct way for achieving to an appropriate estimation of infiltration rate will be so valuable. The present research has been done for determining the best Artificial Neural Network (ANN) model based on the parameters of two models SCS and Kostiakov. According to two applied infiltration models, two ANN models developed so called ANN-1 and ANN-2 respectively. In this research, rain and runoff data were used as the inputting layers to the ANN then two models ANN-1 and ANN-2 were developed. Afterward the best model was selected by some criteria of error assessment, such as percentage of relative error (RE), root mean square error (RMSE), modeling efficiency coefficient (EF) and coefficient of descriptive (R2). After several trial and error runs, optimum structures for two ANN models have been created with 4 and 9 hidden layers respectively. The results showed that ANN-1 developed by SCS infiltration model could estimate the infiltration rate with higher accuracy than ANN-2 crated by Kostiakov infiltration model.

The main objective of current study was application of direct gradient analysis, to identify the most important environmental factors affecting the Morphological characteristics in plant medicinal Verbascum songaricum.In this study species were collected from Rangeland, Howz Vally, Gahiz, Semeiroom intrance and Ghadam places in Isfahan province as well as Dena in Kohgiloye and Boyer Ahmad province. ‌All locations are in the range of morphological, climatic, physiographic and soil physic-chemical properties were investigated. To investigate the plant index and environmental factors were processed and ordination was done using redundancy analyses (RDA). The result show Acidity of the soil, limestone soil and southern longitude first axis order species - environment has a strong correlation (respectively r = 0/87, r = 0/80, r = 0/86) are. Sandy loam of the second axis - the moderate correlation (r = 0/54) is. The average annual rainfall, the average annual number of frost days, damping coefficient and the average height above sea level of the core, Emberger Humidity Index correlation (r = 0/90) are. Clay content and cation exchange capacity of the fourth axis - medium (respectively r = 0/74 and r = 0/54) and moderate to strong correlations. In the current study the result of RDA show the relationship among plant indices of the species with ecological circumstances of the area Overall the survey results showed there are a significant positive correlation between plant indices and environmental factors. Awareness of the relationship between environmental factors and indicators of rangeland vegetation to help us to apply these findings, in the management, restoration and development of pharmaceutical and industrial crops, in endangered species.