ECOPERSIA
Year:2016 | Volume:4 | Issue:4 |Papers Count:7

The moisture flux convergence (MFC) and relative humidity in dusty days at different times and levels over the Alvand Mountain was investigated. The required basic data for the years 2009-2012, including relative humidity, visibility and synoptic codes, were gathered from Hamadan synoptic station, while sea level pressure, uwind, vwind and specific humidity data were gathered from NCER/NCAR site. The dusty days were categorized into four groups, according to WMO protocol. Sea level pressure (SLP) patterns were classified using cluster analysis (CA). MFC function, jet stream and omega maps were computed using special moisture and horizontal and vertical components of wind, SLP and omega data in various levels and times for each sea level pressure pattern. The results showed 6 categorized patterns of sea level pressure. The highest values of MFC were observed at 1000, 925 and 850 hPa levels and at 12: 00 and 18: 00 UTC. MFC value strongly decreased in dusty days at the 700, 600 and 500 hPa and at 06: 00 UTC. The relative humidity significantly decreased at 12: 00, while the maximum increase was recorded at 18: 00 and 00: 00 UTC.

The effect of drought indices on hydrostatic variations and qualitative parameters of the Zahedan Plain's aquifer was investigated. For this purpose, 12-year statistics from observational and piezometry wells in the plain, the drought index of percentage normal) PN), standardized precipitation index) SPI (, and 30-year precipitation statistics of Zahedan station were used. Results revealed that the PN index had a greater variety than SPI. The aquifer hydrograph showed a rise of 1.37 m in water level from the year 2002-2003 to 2013-2014. Considering the drought conditions in the plain, this rise in the water level can be attributed to the reduced water extraction from the aquifer, because the water requirement of Zahedan city was supplied from other sources, viz. Chah-nimehs. Also, there was a significant correlation between the parameters of anion, TDS, and Na+with SPI. However, PN index did not have any significant relationship with the quality parameters. There was a significant correlation between water level balance and SPI only at the level of 1%.

The optimal cropping pattern for Sistan water resources management was determined through a goal programming technique within the GAMS programming environment. Results showed that the optimum cultivation area and net profit of the agricultural sector in the Sistan region could increase up to 18.1 and 39.8%, respectively, compared to the current status. An increase in the farm irrigation efficiency from the current 35 to 55% would increase the net profit of the agricultural sector by 49.7% despite 6.4% reduction in water consumption. At the same time, 20% increase in the efficiency of water delivery system to farmlands would lead to 8.2 and 17.2% increases in the cultivation area and net profit, respectively. The results of combining these two management scenarios indicated that farming net profit would increase by 64.3%, while total water consumption in agricultural sector would decrease by 2.3%. Under wet condition, cultivated area and net profit would respectively increase about 32 and 44%. However, upon drought years, the cultivated area and net profit would experience 86.9 and 87.3% loss, respectively.

The impact of meteorological and hydrological drought on groundwater resources in coastal deserts in the south of Iran was investigated during 1991-2011, using Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), and Groundwater Resources Index (GRI). The results indicated that wet and drought spells governed the area in the first and second decades, respectively, which was similarly reflected by the three indices; GRI had a good correlation with SPI and SRI in 48-month time scale. This correlation was simultaneously in the eastern and western coasts and with a 6 months delay in the central plains. The findings can help to provide reasonable managerial strategy in relation to water resources management in the coastal plains.

Based on SPI and RDI indices, changes in droughts in the semi-arid areas of west Golestan Province was assessed in the GIS environment by incorporating data from Hashemabad synoptic station and 11 climatic stations. After evaluating the ability of LARS-WG5 in the simulation period (1984-2010), downscaling of HadCM3, IPCM, and GFC models was done as a group under scenarios of A1B, A2 and B1 to evaluate changes in meteorological values of precipitation, Tmax, Tmin, and evapotranspiration during 2011-2030.Model accuracy was studied using the coefficient of determination, index of agreement (D) and the mean error. The results showed that the highest mean values of Tmax and Tmin were related to the B1 and A2scenarios, with an increasing trend of 0.81and 0.91oC, respectively. The highest mean evapotranspiration (1.34 mm) changes were under group model of B1 and A2. For precipitation, these were related to B1 (1.49 mm) and A1B (1.36 mm) scenarios. Based on the regional interpretation of drought, the central, northern and eastern parts, in spite of the current droughts, are predicted to be hit harder in the upcoming period and for more prolonged period. In this study, performance of group models to simulate climate data and use of drought indices were shown.

The occurrence of dust storms and their sources in the southern and central parts of Iran during the period of 2002 to 2009 was investigated. For this purpose, the meteorological and synoptic data, data from the middle and upper atmosphere, and wind flow tracking model were used. Dust storms and NDDI were traced using satellite imagery from Fasa, Shiraz, and Bushehr stations. Analysis of the ground data indicated that one of the strongest storms occurred in 2008 and the most intense dusty day was June 10, 2008. The results of tracing wind flow in the fiercest dusty day using HYSPLIT model indicated that dust masses originated from the western parts of Iraq and eastern Syria and transported by the northwest winds in the region. The results indicated that west winds are caused by the presence of the low pressure air mass in the center of Iran and the high pressure air mass in the northeast of Africa. It is concluded that terrestrial measurements, weather patterns, tracing wind flow model and NDDI index have suitable capability to detect the movement of dust storms.

The phytoremediation capability in Pb removal from the contaminated soils by three native seedlings species (Acer cappadocicum, Fraxinus excelsior and Thuja orientalis) and one exotic species (Cupressus arizonica) were compared. The seedlings were grown in Pb contaminated soils at 0, 100, 200, 300, 400 and 500 mg kg-1 concentrations for 6 months (Mar 21 to Sept.22, 2015), after which the biomass allocation and Pb accumulation in tissues of root, stem, and leaf were assessed. The results showed that the higher Pb levels (400 and 500 mg kg-1 soil) caused significant reduction in growth in all species, but this inhibition was less marked in the two conifer (T. orientalis and C. arizonica) compared to the two broad-leaf seedlings (A. cappadocicum and F. excelsior). Pb concentration in different tissues of seedlings increased with its increase in the soil. Further, Pb accumulation in the conifers was twice higher than that of the broad-leave species. Therefore, this study suggests that the two conifer species (P. orientalis and C. arizonica) can be used for phytoremediation, although further research is needed to make a final decision.