Desert
Volume:19 Issue: 2, Summer - Autumn 2014

Estimated Effective Precipitation (Pe) in dryland areas is an essential element of water resource management. It represents the amount of precipitation available in the crop root zone to meet the needs of evapotranspiration. The current study compared different approaches for estimating Pe in different climatic zones of Iran. A two-layer soil– water balance (SWB) model was adopted based on the proposed approach in which a portion of the previous day’s precipitation saved between the previous and current root-zone development is added to the Pe of the current day. To this end, we used three groups of data (meteorological, phenological, and soil characteristics data) related to 21 agrometeorological stations representing arid, semi-arid, semi-humid, and humid regions of the country. The results of this study indicated that, in spite of data limitations, the new procedure performed appropriately in estimating that part of the wheat yield which could be explained by Pe only. Coefficients of determination (R2) between annual precipitation and Pe ranged from 0.50 in the humid climatic zone to 0.82 in the arid climatic zone. Ultimately, using annual precipitation data collected from 181 Iranian synoptic stations and its correlation with Pe, the first annual Pe map of Iran was produced.

This study aims to evaluate effects of two downscaling methods; change-factor and statistical downscaling on the runoff of the Azam-Harat River located at Yazd province (with an arid climate) of Iran, under the A2 emission scenario for the period of 2010-2039. For this purpose, CGCM3-AR4 model; a rainfall-runoff conceptual model, IHACRES; two downscaling models, Change Factor and LARS-WG were applied. Results show 30% difference in runoff simulated by two downscaling methods. Also, according to the fact that Change Factor ignores climate fluctuations over the course of future period relative to base period, simulated runoff from the outputs of this downscaling method does not contain enough confidence and cannot represent the actual runoff of the basin in the future. Despite, fluctuations are modeled in the LARS-WG well. On the other hand, if the estimated runoff increase from the LARS WG is more than the capacity of the Azam-Harat River and Basin, the risk of flood and damage could figure in the future.

Freshwater resources represent around 3% of all water on Earth, and less than 1% of that is available. Considering current conditions, as well as future predictions of need, freshwater resources cannot meet human needs. Thus, sweetening of the brackish water can be performed to provide freshwater for human use. Solar energy, because of Iran''s climatic conditions, may be used for sweetening the brackish water. The objective of this study was to survey the lands using groundwater resources for the installation of solar desalinations. According to the goal, criteria and indicators were identified by the analyses of previous studies’ data, Delphi method and the internal structure of measurements and indicators determined using the DEMATEL technique. Then, indicators were weighted using the analytic network process (ANP) method, and indicators’ suitable membership functions were defined using fuzzy logic. Indicators have been combined by the means of minimum function. Eventually, the areas were classified into four classes. The results showed that among 250 scope studies, 20 scopes have been put in class one, and these are located in five provinces. The results also indicated that among the provinces of Iran, Yazd is located in an area with the highest percentage of class one, and is ranked first. Comparisons of the obtained results with the climatic conditions of Iran confirmed the results.

energy consumption in the residential sector is a complex socio-technical problem that can be explained using a combination of physical, demographic and behavioural characteristics of a house and its occupants. In this paper, by using the energy consumption data for the residential sector of Shiraz in Iran, the effect of built area (BA) and occupant number (Occ) on annual energy consumption (Ec) was investigated. Ten houses from the first modern period of the city were selected randomly from 1971 up to 1991. It was found that the built area and Occ did not have a direct impact on energy consumption in Shiraz’s residential buildings; however, the household behaviours and houses’ building construction directly affected energy saving. Houses with maximum BA or maximum annual energy consumption were not the same; the same held for Occ. The average annual energy consumption per capita of 1 m2 built area of the case studies was 0.087, and for each occupant it was 2.487.

The impact of air pollution and environmental issues on public health is one of the main topics studied in many cities around the world. Ozone is a greenhouse gas that contributes to global climate. This study was conducted to predict and model ozone of Yazd in the lower atmosphere by an adaptive neuro-fuzzy inference system (ANFIS). All the data were extracted from 721 samples collected daily over two successive years, from April 2012 to 29 March 2014. The concentration of pollutants and meteorological variables including NOX, temperature, wind speed and wind direction were considered as input and ozone (O3) as the output of model. The results showed that among five membership functions used in the model, the Gaussian membership function with R2 equal to 0.949, RMSE equal to 2.430 and correlation coefficient equal to 0.974 was obtained as the best model to predict the concentration of ozone in the lower atmosphere. This study showed that predicting and modelling ozone using an adaptive neuro-fuzzy inference system (ANFIS) is appropriate and, due to the expansion of the city of Yazd in the not too distant future, it is necessary to pay more attention to the permissible threshold values of pollutants such as ozone.

Treatment of soils contaminated with heavy metals using plant species is a method which has been widely used in the past. This method, which is known as phytoremediation, has been applied for pollution treatment using different plant species worldwide. The method has been used for remediation of various types of pollutants in laboratory, pilot and industrial scales. The aim of this study was to compare the capability of heavy metal accumulation in Artemisia aucheri and Astragalus gummifer in the Darre Zereshk deserts located in Taft, Iran. Plant and soil samples were collected from eight stations. After acid digestion, concentration of heavy metals was measured in plant tissues and rhizosphere soil using an ICP-OES instrument. The bioconcentration factors (BCF) and translocation factors (TF) were calculated for each plant species. The BCF and TF in A. aucheri were higher than in A. gummifer. Therefore, it is suggested that A. aucheri has higher capabilities in removing metals from polluted soils and hence is a better option for phytoremediation purposes.

The assessment of de-desertification alternatives can be effective in controlling the reclamation of disturbed land and avoiding destruction of areas at risk. Until now, there has been no method to consider different criteria and alternatives, or to present the optimum alternatives based on systematic structures and experts’ perspectives. Desertification is a complex process resulting from various factors, including anthropogenic activities; the selection of optimum alternatives is a very difficult task. This paper attempts to represent the optimum alternatives based on the Multiple Attribute Decision-Making Model (MADM). For this purpose, the initial priorities for alternatives were determined by Expert Choice (EC) software via Elimination and Choice Translating Reality (known as ELECTRE). Then, the final priorities for alternatives were assessed using the Analytical Hierarchy Process (AHP). This model was tested in the Khezr Abad region, Yazd Province, to evaluate the determination of optimum alternatives. The results indicated that prevention of unsuitable land use changes, vegetation cover development and reclamation, and changes in groundwater harvesting, with weight averages of 22.9, 21.8 and 19.1 %, respectively, are the most important desertification alternatives in the study area.

Drought detecting is a necessary aspect of drought risk management. It is generally performed using different drought indices that are effectively continuous functions of rainfall and other hydro- meteorological variables. A number of drought indices have been introduced and used in various countries to date. In the current research, four meteorological drought indices including the standardized precipitation index (SPI), China-Z index (CZI), modified CZI (MCZI) and Z-Score (Z) are compared and evaluated for monitoring droughts in Salt Lake Basin in Iran. The comparison of indices was carried out based on drought classes that were monitored in the study area using 40 years of data. The results indicated that SPI, CZI and Z-Score performed similarly with regard to drought identification and responded slowly to drought onset. DI appeared to be very sensitive to precipitation rates, but had unsteady spatial and temporal variation. Additionally, by considering the advantages and disadvantages of the mentioned drought predictors in Iran, the CZI and ZScore could be used as good meteorological drought predictors.

Arid and semi-arid lands cover around one-third of the world''s terrestrial expanse and their widespread plant distributions provide these areas with a high potential for sequestering carbon. Vegetation management for developing shrub or tree species in arid and semi-arid regions is one inexpensive and multi-purpose approach for decreasing CO2. This study assessed the potential of carbon sequestration in the soil and biomass of a Nitraria schoberi L. stand in central Iran. Samples were taken from in N. schoberi L. stand and the adjacent native vegetation (Halocnemum strobilaceum M. B. and Seidlitzia rosmarinus (Ehrh.) Bge.) as control area at Hoze Soltan desert region. In both areas, the amounts of aboveground and underground biomass of plant samples were calculated by cutting and weighing the aerial parts (leaves, stem) and roots. The ash method was used to determine the carbon sequestration coefficients of all samples and soil organic carbon (SOC) was measured using Walkley and Black''s methods. A comparison between the SOC of planted and control areas showed no difference regarding the ability of carbon sequestration between the two areas. The results indicated that the total carbon sequestration of the N. schoberi L. stand (28.06 Mg/ha) was significantly higher (p<0.01) than the control area (18.64 Mg/ha) in the Hoze Soltan region.

Land suitability analysis, commonly known as land evaluation, is considered an interface between land resource survey and land use planning and management. Land evaluation be carried out to estimate the suitability of land for a specific use such as arable farming or irrigated agriculture. There are several established techniques for generating land suitability evaluation. This research was carried out to evaluate the capability of a combined fuzzy AHP method for land suitability evaluation for barley crops in the southwest of Iran, and to compare the results with the standard method of the FAO framework. Eight soil parameters were chosen for cropland suitability analysis and thematic maps were developed with Kriging method for each of these parameters. Different fuzzy membership functions obtained from the literature were employed and weights for each parameter were calculated according to AHP. Landscape and soil requirements for barley were determined based on the FAO method. Finally, land suitability classes were provided for each land unit. Comparing the results with expert judgments shows that the fuzzy AHP method has a higher accuracy than the standard FAO method. Further development of the fuzzy AHP method would be advantageous for improving the accuracy of land suitability analysis.