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Showing 72 results for Drought

M. Mohammadi, M. Baum,
Volume 12, Issue 45 (10-2008)
Abstract

Improving the drought tolerance of barley varieties through the integrated efforts of plant biotechnology and conventional breeding is an important objective in barley breeding. One hundred and fifty eight doubled haploid lines of barley were mapped with 50 SSR and 93 AFLP markers. Agronomic traits such as early growth vigor, plant height, peduncle length, extrude of spike from flag leaf, spike length and kernel per spike were evaluated at ICARDA research stations, Tel Hadya and Breda, during 1382-1383. Genetic correlation between grain yield and considered traits suggested that important traits for high yield in both stations were rapid early growth, short plant height, more extrude of spike from flag leaf, and more kernel per spike. But peduncle length exhibited a different roles in both environments. For plant height, eight Atlas on chromosomes 2, 3, 4, 5, 6 and 7 were identified in Tel Hadya and Breda. Two of these QTLs were shown co-located with peduncle length QTLs. The QTLs which is linked with Bmag13 marker on chromosome 2, explained 42 percent of phenotypic variation for kernel per spike in Tel Hadya. Identification of these QTLs for agronomic traits is the first step to analyse and dissect more complex characters for barley adaptation to drought stress conditions.
M. Dehghanian, M. Madandoost,
Volume 12, Issue 45 (10-2008)
Abstract

In order to investigate the effect of zinc - chelate on drought tolerance of Azadi cross wheat, a randomized complete block design was conducted as split plot with three replicates in the Kherameh during 1383 - 1384. The main plot was four drought levels (control and drought stress in the stages of flowering, seed milk stage and two phases, together), and sub plot was zinc - chelate rates 0, 5, 10 & 15 kg per hectare. The results showed that zinc application under drought conditions increased spike per square meter significantly at the 5% level. Drought stress decreased 1000 - seed weight. Least of 1000 - grain weight was in two phases of flowering and seed milk stage together (29.78 g). The application of 15kg zinc -chelate fixed 1000 - seed weight. Treatments of drought stress decreased seed yield significantly (14.17% in the proportion of control), but zinc - chelate application increased wheat tolerance to seed yield decrease. Zinc - chelate application prevented from seed number decrease per wheat spike under drought conditions that was caused to tolerance of seed yield and harvest index decrease. The application of 15 kg zinc - chelate increased harvest index in comparison of control amount of 22%.
S.s. Pourdad, K. Alizadeh, R. Azizinegad, A. Shariati, M. Eskandari, M. Khiavi, E. Nabatee,
Volume 12, Issue 45 (10-2008)
Abstract

Safflower (Carthamus tinctoius L.) is an Iranian native crop that is adapted to different environmental conditions of this country. Sixteen safflower varieties/lines were spring-planted in 6 research stations including Sararood (Kermanshah), Maragheh, Ghamlo (Kordestan), Khodabandeh (Zanjan), Shirvan (North Khorasan)and Khohdasht (Lorestan) with and without drought stress conditions each in a RCBD with 3 replications. Some drought resistante indices including Mean of Productivity (MP), Geometric Mean of Productivity (GMP), Tolerance (TOL), Stress Tolerance Index (STI), Stress Susceptibility Index (SSI) for seed yield and genotypes Cell Membrane Stability (CMS) were calculated. Results showed that STI was the most appropriate index to identify drough resistant genotypes. Estimation of STI from mean of all stations revealed that Gila, CW-4440 and PI-537598 with high STI showed high seed yield in both stress and non-stress conditions. Caculation of STI standard deviation for these genotypes showed that Gila had less STI stability over the locations than other two genotypes so, CW-4440 and PI-537598 are more stable in drought stress resistance. Analysis of variance for cell membrane stability (CMS) of genotypes showed the significant differences in 1% level of probability between genotypes. S-541 had the highest and Kino-76 had the lowest CMS. There were significant and strong correlations between STI, MP and GMP with CMS namely, genotypes with more stable membrane having more drought resistance in field condition. So, cell membrance stability can be a useful and fast method to screen germplasm and identify drought resistant genotypes. Cluster analysis based on STI,MP,GMP, CMS and seed yield in both stress and non-stress conditions divided genotypes into 3 groupes. Results of clustering also identified S-541, Gila, CW-4440 and PI-537598 as 4 superior genotypes and confirmed the results of other methods.
A. Moradi, A. Ahmadi , A. Hossein Zadeh,
Volume 12, Issue 45 (10-2008)
Abstract

Drought is a major factor limiting growth and development of crops such as mung bean (Vigna radiate (L.) wilczek) in arid and semi-arid regions of the world. This study was conducted to investigate the effects of different timing and severity of drought stress on physiological traits of mung bean and its relation to grain yield. A field experiment was carried out during 2004 growing season at Experimental Farm of Agriculture College, University of Tehran, Karaj, Iran. The treatments were laid out in a Randomized Complete Block Design (RCBD) with three replications. Plants were exposed to moderate and severe water stresses at either vegetative (VS) or reproductive stages (RS). Physiological traits were measured at the end of vegetative and the middle of pod formation. Generally water stress reduced leaf net photosynthesis rate, stomatal conductance and leaf relative water content at different growth stages. The effects of RS treatments were more severe than that of VS one. Severe VS treatment increased photosynthetic water use efficiency, whereas RS treatments decreased it significantly. However, leaf area index and total dry matter were more responsive in VS compared to RS treatments. VS treatments did not affect harvest index, while RS treatments reduced it significantly. Drought stress also reduced grain yield by 9 and 49 % (relative to control plants) in severe VS and severe RS treatments, respectively. Therefore irrigation is critical during reproductive stage mainly because of the higher demand for photoassimilate. It is concluded that to maximize mung bean grain yield in arid and semi-arid areas, appropriate watering should be practiced across all phenological stages in general, and during reproductive stage in particular.
B. Hatami, J. Khajehali, M. R. Sabzalian,
Volume 12, Issue 45 (10-2008)
Abstract

Safflower having oil with high unsaturated fatty acids is a very valuable plant. However the sensitivity of safflower to some pests as safflower fly (Acanthiophilus helianthi), particularly in drought stress conditions has limited its production. In order to evaluate the effect of drought stress on population density and damage of important safflower pests, especially safflower fly, an experiment was conducted in the field using 5 irrigation treatments including 50, 70, 90, 110 and 130 mm evaporation from class A pan in a randomized complete block design with three replications. The local safflower variety used in this study was Isfahan land variety, Kooseh. In each irrigation regime, the half of one plot was locally sprayed by Chlorpyrifos in 2ml per liter of water to be compared with non-sprayed part. During 8 weeks of sampling, population of aphids, Uroleucon carthami, leafhopper, Empoasca decipiens and safflower fly, A. helianthi and also percentage of damaged heads by safflower fly were measured. The results showed that in non-sprayed conditions, the highest safflower fly (2.38 flies per net) and aphid population (165.57 aphids per plant) was observed at 130 mm evaporation regime. Drought stress also decreased (30.23 %) safflower seed yield. Severe drought stress together with non-spaying may increase safflower pests population particularly safflower fly and reduce seed yield. However low level of drought stress (70 mm evaporation from class A pan) may decrease relative number of insects and save irrigation water. Drought stress also decrease the population of leafhopper. In this study, 70 mm evaporation regime was the optimum irrigation treatment regarding lower aphid and fly damage (15.86% damaged heads in non-sprayed condition) and higher safflower seed yield (1687.5 kg/ha in sprayed condition).
S.mj Nazemosadat, H Ghaed Amini Asadabadi,
Volume 12, Issue 46 (1-2009)
Abstract

The Madden–Julian Oscillation (MJO) known as the dominant mode of tropical and extratropical intraseasonal variability has an important role in the coupled ocean-atmosphere system. This study investigates the eastward propagation of the MJO and its impact on monthly (February-April) maximum and minimum precipitation in Fars Province. The positive and negative phases of MJO were categorized for the period 1979-2002. The maximum and minimum values of monthly precipitation was then determined for each phase as well as for the entire length of records. The given results have indicated that, in February, both maximum and minimum precipitation during negative phase were significantly greater than the corresponding values during the positive phase. This implies that the enhanced February precipitation and flood events are associated to the negative MJO phase. On the other hand, severe water shotage in February was linked with prevalence of the positive phase. The results for April were mostly found to be similar to February except that minimum precipitation was not significantly associated to the positive phase. In contrast to February, minimum monthly precipitation in March was found to coincide with the negative MJO phase. Maximum precipitation, however, could coincide with neither of extreme phases of MJO.
A Masjedi, A Shokohfar, M Alavi Fazel,
Volume 12, Issue 46 (1-2009)
Abstract

The increasing cultivation of corn in Ahwaz and the direct relation between the increase of the summer corn yield and its perfect irrigation in sowing period all together have made the research regarding this crop necessary. Deciding over the suitable irrigation scheduling of corn (hybrid SC.704) in summer by utilization of class A evaporation pan is the focal point of this research. Accordingly, a project was conducted in the form of stadistical perfect accidendal block in four repetitions and four treatments in 1383 on Ahwaz Azad university research land situated in Choneibeh. The irrigation treatment had four levels of T1,T2,T3 and T4 in class A evaporation pan containing of four levels of 50,75,100 and 150 mm, carried out in split plot. The suitable irrigation period was chosen according to the best treatment performance and its components, and the total amount of water in the taking period defines the depth of irrigation. The soil texture is clay lomy silty and the internal soil is silty clay. According to the amount of the accumulated evaporation from class A evaporation pan and taking the plant coefficient (Kc) into consideration, the amount of needed evapotrans piration was calculated and the amount of needed water for plot was measured by water counter. Then a comparison between the means by the use of Donken multi domains test was made and in this way the superior treatment was selected. Accordingly, the most suitable time for irrigation of summer corn in Ahwaz was after 50 mm of accumulated evaporation from class A evaporation pan which equals ten irrigation in the growing period. So in order to acquire 12 tons of seed yield in each hectare, at least 9600 m^3 of water for every hectar is needed. However, given the equal amount of water, with 3 times decrease in irrigation in treatment T2 in comparison with T1, a performance near 11 tons and with five times decrease in irrigation and ten tons in treatment T3 a performance near 10 tons can be attained.
Z Amini, R Hadad, F Moradi,
Volume 12, Issue 46 (1-2009)
Abstract

The effects of irrigation, dry farming and drought treatments on the activities of antioxidant enzymes including superoxide dismutase, ascorbate peroxidase, catalase and peroxidase in barley leaves at different generative growth stages under field conditions were investigated. Three senescence parameters including chlorophyll, total soluble protein and rubisco large subunit protein loss, were also studied in order to compare our results to those reported by other researchers. The results showed that leaf relative water content (RWC), chlorophyll and total soluble protein and rubisco large subunit protein content declined with leaf age and the effect of water deficit. The activity of superoxide dismutase declined with the progress of the leaf age on all treatments but ascorbate peroxidase activity declined with leaf age only in irrigated (control) plants. There were no significant differences among developmental stages in catalase activity in control plants, while catalase activity declined in the water dry farming and drought stress conditions. Peroxidase activity increased with the progress of senescence for all of treatments in such conditions. Water deficit stress triggered increases in antioxidant enzymes activities. Results showed that among all studied enzymes, peroxidase has a key role in increasing resistance to oxidative stress on both the senescence stages and drought stress condition in Hordeum vulgare.
A Ahmadi, M Jodi, A Tavakoli, M Ranjbar,
Volume 12, Issue 46 (1-2009)
Abstract

The objective of this study was to evaluate some morphological characteristics associated with grain yield potential on 20 bread wheat cultivars under two irrigation and drought stress conditions. The experiments were conducted at Research Farm of Agriculture College, University of Tehran, Karaj during 2001-2003. Twenty bread wheat cultivars were planted as subplots within each irrigation main plots in randomized complete block design with 3 replications. Drought stress was imposed at the end of flowering, and plants were re-watered when they showed signs of wilting, particularly during the morning. The results showed that the interactions between cultivars × year and cultivars × irrigation were significant for the grain yield. The cultivars showed significant differences in grain yield under drought stress condition in 2001-2003. Roshan, M-79-4 and Alvand in 2001-2002 and Azadi, Marvdasht and M-79-17 in 2002-2003 were most productive under drought stress condition, whereas C-79-12, MV-17 and Shahpasand in 2001-2002 and M-79-4, Roshan and Nicknajad in 2002-2003 performed visa versa. Correlation between grain yield and measured traits under irrigation condition was different from drought stress condition, suggesting that grain yield controlling mechanisms operate differently under these conditions. Drought stress caused a reduction in 1000 seed weight of cultivars. High 1000 seed weight and high grain number per ear were accompanied by high grain yield in drought stress and irrigation conditions, respectively. In the present study, clear relationship between grain yield and ear length was not observed.
Gh Dehghani, F Malek Shhi, B Alizadeh,
Volume 13, Issue 48 (7-2009)
Abstract

Canola (Brassica napus L.) as one of the oilseed crops has recently received lots of attention due to its suitable oil quality and high oil percentage. To evaluate the effect of water deficit stress on canola genotypes with regard to yield, drought tolerance quantitative indices and identify drought tolerant genotypes, an experiment was conducted in research farm of seed and plant improvement Institute (Karaj) using completely randomized block design with four replications, and 25 genotypes under two stress and non stress conditions. Genotypes were evaluated regarding drought tolerance. Drought tolerance quantitative indices include MP, GMP, STI, SSI and TOL. Result of variance analysis showed significant differences among genotypes as regards all indices and seed yield of genotypes in both conditions at 1% probability level. MP, GMP and STI indices were selected as the best indices for selection of tolerant genotypes in regard to analysis of correlation between seed yield in two stress and non stress conditions and drought tolerance indices. Results indicated that Genotype Vectra was the best genotype, because of its proper mean yield in both stress and non stress conditions. Multivariate biplot figure display showed that MP, GMP and STI indices had high correlation coefficient with each other, and tolerant genotypes were located near tolerance indices. Also results of three dimensional scatter plot and cluster analysis indicated that genotypes Modena, Jura, Eshydromel, Vectra, Dante, Zarfam, Esbetty and Olano were tolerant to drought stress, and genotypes Olpop, GKHelena, RG4504 and Olphi were sensitive genotypes.
M. Karimi Kakhaki , A. Sepehri,
Volume 13, Issue 50 (1-2010)
Abstract

In order to study the effect of deficit irrigation at reproductive growth stages on water use efficiency and drought tolerance of four sunflower cultivars, including Azargol, Allstar, Alison and Euroflor, an experiment was conducted during 2007 growing season at experimental field of Agricultural Faculty of Bu-Ali Sina University, Hamadan, Iran. The experiment was a split plot based on randomized complete block design with three replications. The irrigation levels included full irrigation, deficit irrigation at heading, deficit irrigation at flowering, deficit irrigation at seed filling, deficit irrigation at heading and seed filling and deficit irrigation at flowering and seed filling stages. The biological and economic yield (BY and EY), harvest index (HI), water used, water use efficiency (WUE) and water stress indexes were measured. The results indicated that the highest BY (11681.7 kg.ha-1), EY (4854.0 kg.ha-1) and HI (42%) were obtained from full irrigation treatment. The lowest negative effects in cultivars belonged to deficit irrigation at seed filling stage. Euroflor obtained the highest of these parameters with 10127.1 Kg.ha-1, 4081.5 Kg.ha-1 and 40% respectively. Highest WUE was related to twice cutoff of irrigation in flowering and seed formation stages and then without irrigation in seed formation stage by 1.09 and 0.96 Kg.m-3. Allstar and then Euroflor had highest WUE among sunflower cultivars by 1.01 and 0.94 Kg.m-3 respectively. Results also indicated that Euroflor was a tolerant cultivar and STI (Stress Tolerant Index) and GMP (Geometric Mean Productivity) were acceptable indexes for selection. Finally, deficit irrigation at seed formation stage had the lowest negative effect on yield and HI with suitable WUE. In addition, Euroflor showed the highest yield, drought tolerance and HI with suitable WUE.
Afkhami, Dastorani, Malekinejad , Mobin,
Volume 14, Issue 51 (4-2010)
Abstract

Drought is a natural feature of the climate condition, and its recurrence is inevitable. The main purpose of this research is to evaluate the effects of climatic factors on prediction of drought in different areas of Yazd based on artificial neural networks technique. In most of the meteorological stations located in Yazd area, precipitation is the only measured factor while generally in synoptic meteorological stations in addition to precipitation some other variables including maximum and mean temperature, relative humidity, wind speed, dominant wind direction and the amount of evaporation are also available. In this research it was tried to evaluate the role of the type and number of meteorological factor (as inputs of ANN model) on accuracy of ANN based drought prediction. Research area is a part of Yazd province containing only one synoptic and 13 non-synoptic meteorological stations. Three-year moving average of monthly precipitation was the main input of the models in all stations. The type of ANN used in this study was time lag recurrent network (TLRN), a dynamic architecture which was selected by evaluation of different types of ANN in this research. What was predicted is the three-year moving average of monthly precipitation of the next year, which is the main factor to evaluate drought condition one year before it occurs. For the Yazd synoptic meteorological station, several combinations of input variables was evaluated and tested to find the most relevant type of input variables for prediction of drought. However, for other 13 stations precipitation data was the only variable to use in ANN models for this purpose. Results in all stations were satisfactory, even where only one input (precipitation) was used to the models, although the level prediction accuracy was different from station to station. Result taken from this research, indicates high flexibility of ANN to cope with poor data condition where it is difficult to get acceptable results by most of the methods.
R Mohsen Pour, M Zibaei,
Volume 14, Issue 52 (7-2010)
Abstract

Drought is among the most costly weather-related events and Iran is highly vulnerable to the economic, social and environmental impacts of drought In this study expected profit maximization model and utility efficient programming were applied to determine optimal crop pattern, expected gross margin and water use with and without, drought condition at representative farms of homogenous groups. This study was based on two databases. A sample of 180 farmers was selected for interview and collected necessary farm level data in 2007. The sample farms were drawn using two-stage stratified random sampling method. Results indicated that the largest reduction in expected profit is directed toward farmers who use surface water from river or canal. These groups of farms ultimately suffered a severe reduction in expected income (53%-64%) as a consequence of the drought, largely because their access to water was cut substantially. The least quantity of damage is directed toward homogenous groups of farms that use groundwater or conjunctive use of groundwater and surface water. Reduction in expected income of these groups is equal to 7 and 32 percent of expected income in the normal year, respectively. Finally, the results showed that the pattern of release water from gate of Drodzan have not been optimal in the planting years 2001-2002 and 2006-2007 based on the calculated shadow price of each cubic meter water in different deciles of year.
Sh. Javanmardi , R. Fotovat , J. Saba,
Volume 14, Issue 53 (10-2010)
Abstract

Osmotic adjustment is generally regarded as an important adaptation of wheat to drought. Because it helps to maintain turgor and cell volume, osmotic adjustment is often thought to promote growth, yield, or survival, of plants in dry soils. However, a physiological rationale for such views is lacking. This study was conducted to determine the effect of osmotic adjustment and some of its components on the wheat yield. Ten bread wheat cultivars were grown in pots under different watering levels using a split plot design. During grain filling stage, RWC, leaf sugar content, proline content and osmotic regulation were estimated by sampling flag leaf under normal and stress conditions. Main stem was used for measuring sugar content of different parts of stem. Although there were some differences in osmotic regulation in wheat lines, there were no relationships between yield and osmotic regulation. It was shown that these components probably have a little share in wheat osmotic regulation.
M. Gholamzadeh, S. Morid, M. Delavar,
Volume 15, Issue 56 (7-2011)
Abstract

Application of drought early warning system is an important strategy for drought management. It is more pronounced in the arid regions where dams have vital role to overcome water shortages. This papers aims to develop and apply such a system that includes three main components, which are 1) drought monitoring, 2) forecasting inflows and water demands and 3) calculation of a warning index for decision about drought management. The system is presented for the Zayanderud Dam. For this, the future six months river inflows and demands are forecasted at different probabilistic levels using the artificial neural networks and considering respected uncertainties. Also, five drought levels are indicated based on the historical records of dam’s storage and the self organizing feature map technique. Furthermore, a drought alert index (DAI) is defined using current storage of dam and the forecasted flows and demands. Finally, the different alert levels are estimated, which vary from normal to sever water scarcity. The results showed that application of the designed warning system can have effective role in the dam’s operation, rationing policy and reducing drought losses.
H. Nadian,
Volume 15, Issue 57 (10-2011)
Abstract

Effect of drought stress and mycorrhizal symbiosis on growth and phosphorus (P) uptake by two sorghum cultivars different in root morphology was studied in a pot experiment. A factorial experiment with a randomized complete block design was performed. In this study, sorghum speed feed cultivar with high root proliferation and branching and sorghum KFS2 cultivar with low root proliferation and branching were colonized by Glomus intraradices. All plants were watered equally in the first three weeks to establish them. Drought stress was applied from the week four and the plants were watered when 40% (T1), 60% (T2) and 80% (T3) of the available water was consumed. Results showed that in both sorghum cultivars, plant dry weight decreased as drought stress was increased. However, dry weight of mycorrhizal plants was higher than that of non-mycorrhizal plants at all levels of drought stress. This increase for speed feed cultivar was greater than for KFS2 cultivar. Phosphorus concentration and total P uptake in shoot of both mycorrhizal plants were greater than those of non-mycorrhizal plants. P accumulation in both cultivars decreased by increasing drought stress due to the decline in plant biomass. However, P accumulation per unit length of colonized root increased by increasing drought stress. The greater percentage of root colonization and the increased total length of external hyphae per unit length of colonized root of KFS2 cultivar led to an increase in mycorrhizal growth response and improved P nutrition of KFS2 cultivar compared to those of speed feed cultivar.
E. Shayegh, S. Soltani ,
Volume 15, Issue 57 (10-2011)
Abstract

In this research, 5 percent of normal Precipitation Index (PNPI),Deciles of Precipitation(DPI),Rainfall Anomaly Index (RAI), Bahlme & Mooley Drought Index (BMDI) and standardized Precipitation Index (SPI) were used in order to investigate drought in Yazd synoptic station and 31 non synoptic stations all around this province. For this purpose, the present statistical errors were reconstructed via correlation between the stations, after raining data collection from the considered stations. Then, calculation of PNPI, DPI, RAI, BMDI and SPI indexes were calculated on monthly and annual scales. Situation of drought was determined based on the obtained values from calculation of each index according to tables related to the considered indexes in different classes of drought during the statistical period. Then indexes were compared to each other, considering drought given situation for each station. The difference and similarity of each index with other 4 indexes were calculated and investigated. Also after determination of drought situation in each station, given percentage of drought different situations via each Index was determined on annual scales, in 33 study stations. After passing the above mentioned stages, it was found that there was the highest percentage value of similarity between the two indexes RAI & DPI, as both indexes indicated similar situation of hard drought in the stations. These two indexes are considered most efficient to investigate aerology drought. But considering that static indexes are faced with problem on monthly scales and in stations located in drought regions, it is recommended to use‌ SPI & BMDI dynamic indexes whose similarity percentages are acceptable.
S. S. Eslamian, M. Ghasemi, S. Soltani Gerdefaramarzi,
Volume 16, Issue 59 (4-2012)
Abstract

In this study, in order to determe low flow conditions in Karkhe watershed, 5 indices of Q7,10, Q7,20, Q30,10, Q4,3 and Q95 were used for analyzing 12 hydrometric station data in the years of 1345-46 to 1380-81. Discharge data homogeneity was performed by Run Test. The Q95 index was determined by flow duration curve (FDC) and other indices were determined using 4, 7 and 30-day low flow frequency analysis. After calculating the indices, periods of low flows were determined. The indices were regionalized by Kriging method. The results showed that for the most stations, low stream flows happened in the years of 1345-46, 1377-78, 1378-79, 1379-80 and 1380-81 and the percentages of stations having low flows in these years were 68, 92, 84, 75 and 59, respectively. According to the regional maps of low flows in Karkhe watershed, maximum low flows are located in central and southern areas and all of the mentioned indices decrease from south to the north of this watershed.
M. Khodagholi, R. Saboohi, Z. Eskandari,
Volume 18, Issue 67 (6-2014)
Abstract

The geographical location of Isfahan province has led the province to be at risk of drought. One of the ways to mitigate drought is evaluation and monitoring of drought based on indices that can determine its intensity and permanence in each region. In this research, for drought and trend analysis standard precipitation index and Mann-Kendall test were used, respectively. Also, monthly precipitation time series of Isfahan province was applied to forecast drought from 1970 to 2009. For this purpose, Box and Jenkins modeling approach (1976) was used which has three main steps, namely model identification, parameter estimation, goodness of fit test or time independency and normal test of residual. The results showed that most of the stations in Isfahan province were faced with severe drought in the year 2000 and this situation was repeated one more time in 2008. Also, the results brought forth multiplicative models in all the stations. ARIMA (1,0,0) (0,1,1) showed the highest correlations between control and forecast data in Isfahan, Meime and Ardestan stations, and the model ARIMA (0,0,1) (0,1,1) displayed the highest correlation between control and forecasted data in Naein, Freydoonshahr, Khansar and Natanz. These models were selected as the best models through which the amount of precipitation was predicted till 2015. The trend of forecast data across Isfahan province showed that in most months the trend is not significant.
S. Ghaseminejad, S. Soltani, A. Soffianian,
Volume 18, Issue 68 (9-2014)
Abstract

Drought is a one of the most important natural disasters that have high socio-economic and environmental impacts. However, drought is more than a physical phenomenon or natural event. Its impact results from the relation between a natural event and demands on the water supply, and it is often exacerbated by human activities. The traditional approach to drought management has been reactive, relying on crisis management. Due to the drawbacks of crisis management, employing proper risk management techniques has been suggested. In order to move from crisis management to risk management, in this study, risk of drought in Isfahan province was evaluated. Drought hazard index and vulnerability index are components of the drought risk management. Standardized Precipitation Index (SPI) was used as the index of drought hazard. For the calculation of SPI, the monthly rainfall data in 47 meteorological stations during the period of 1975-2007 were collected. The time series of rainfall data were prepared and for calculation of the standardized precipitation index in a 12 month timescale they were imported to SPI program. Percentage of drought occurrence in each severity was calculated and then the drought index map was obtained. Vulnerability index was calculated through socio-economic indicators (population density and percentage of people involved in agriculture), and physical indicators (available water capacity of soil and land use). Weighted Linear Combination (WLC) technique was applied for combination of vulnerability indicators. To assign weights to the criteria, an Analytical Hierarchy Process (AHP) was used. After providing the maps, fuzzy membership functions for every criterion were used for their standardization. For the weighting of the criteria, a questionnaire was prepared and criteria comparison was done using the participatory approach by a group of experts. Finally, the drought risk index was calculated by multiplying the drought hazard index and vulnerability index. The results showed that hazard of very severe drought is mainly concentrated in the central part of province. The North and North East of Isfahan province could experience condition of severe drought. South West of Isfahan province is under moderate drought condition compared to the other parts of the province. Map of drought vulnerability index showed that the most vulnerability is in the West, South and North-East of province. Map of drought risk index showed that the Northern Province demonstrated high risk. To reduce the drought risk in Isfahan province, improving monitoring, early warning, increasing environmental awareness, and promoting water resource management practices should be considered.

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