جستجوی مقالات مرتبط با کلیدواژه « pearson correlation » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Studies on the biocultural diversity are important in complicated social-ecological systems of natural areas and especially in the biosphere reserves to understand the relationships between human society and natural environment. In this study, the Index of BioCultural Diversity (IBCD) was measured using ten cultural indicators of dialect, religion, customs, clothing, handicrafts, traditional architecture, food, livelihood, and beliefs, play and entertainment and three biodiversity indicators of birds, mammals, and plants in Hamoon biosphere reserve between 2020 and 2021. Indices of cultural diversity were calculated using Shannon-wiener based on the 30 questioners and their random distribution between people in nine villages next to the wetland areas of biosphere reserve.  Biodiversity indices were measured based on the determination of proportion of plants and animal species number to total species number and then calculation the average between them. With using average of biodiversity and cultural diversity, an index of biocultural diversity was calculated. With preparing maps of biodiversity scape, cultural diversity scape and their overlapping, bio-cultural landscape was provided. The rate of biocultural diversity (1.126) indicates the poor state of biosphere reserve. The correlation between cultural diversity and biodiversity shows that the indicators of diversity of beliefs and diversity of customs and diversity of traditional architecture did not have a significant correlation with any of the indicators of cultural diversity and biodiversity (P>0.05). In return, there was a significant positive correlation between the livelihood, food and handicrafts diversity with plants and animals’ diversity (P<0.05). In general, the assessment of the bio-cultural diversity of the Hamoon biosphere reserve showed that in the areas where the biodiversity had better conditions, the cultural diversity was parallel to it, which shows that the cultural and biological diversity are affected by each other. The results of the study are important for the managers of the protected areas and indicate that for environmental management, the approach should not be only the approach of biodiversity protection, but the management of these areas should be focused in a correct and sustainable manner with the attitude of biocultural diversity management.

This research has done to study the relationship between dust storms frequency and climatic factors included monthly rainfall data, monthly average temperature, monthly maximum temperature, maximum wind speed, frequency of dust occurrence from internal Sources and SPI in northern, Central and coastal part of Jarrahi watershed (cities of Ramhormoz, Omidieh and Mahshahr port) in Khouzestan province were investigated. First of all linear trend in time series using Mann-Kendall test was assessed. Then, using Pearson correlation, the dependence of the dust storm and climatic factors was studied and with path analysis beta weight or participation of each factor in explaining the variance of dependent factor. The results showed that, except in the occurrence of dust phenomena, linear trend is not observed with a gradient (Sen's Slope) of 2 days in 10 years and Pearson correlation confirmed the significance of the dependence of the occurrence of dust on climatic factors at 1% level. The results of the path analysis indicate that two factors of mean temperature and monthly maximum temperature, directly and indirectly, affect the maximum wind speed by more than 50% of explaining the variance of dust storms. The result of a partial correlation matrix showed with temperature effects control none of the climatic factors in storm dust except maximum wind velocity is significant. Thus, the average monthly temperature and maximum temperatures not only directly but indirectly cause changes in other climate factors. Totally climatic factors explain 15% of the variance in the frequency of storm dust.

Drought as a complex ecosystem crisis can affect vegetation density and health. Iran with an arid and semi-arid climate is exposed to this phenomenon. Therefore, it is necessary to evaluate the effect of drought on vegetation. The purpose of this study is to evaluate the effect of meteorological drought on vegetation dynamics in Iran. In this regard, using MATLAB software, SPEI index with time scales of 3, 6, 9, and 12 months years was calculated and zoned for 99 meteorological stations with a statistical length of 30 years in Arc GIS software. In the next step, the highest value of EVI index per month was obtained from MOD13Q1 MODIS sensor product for the period 2001-2019. Then, using Terrset software, the correlation and slope of EVI index changes were calculated based on SPEI index changes. The results showed that in 18.46, 22.63, 30.77, and 28.14% of the total area of Iran, the SPEI of 3, 6, 9, and 12 months have the highest correlation with vegetation, respectively. The results of linear regression analysis showed that in Lut plain and the heights of Alborz and Zagros mountain ranges, the sensitivity of vegetation to meteorological drought is much lower and the slope of the line has been negative. While the central, southwestern, southeastern, and coastal areas of the Persian Gulf have a positive line slope and vegetation has shown great sensitivity to meteorological drought. According to the obtained results, it can be concluded that climatic conditions, topography, type of vegetation, geographical location, and human management are effective in determining the relationship between the two indicators of vegetation and drought. As a result, it is suggested that in future studies on the effect of climate change on vegetation, factors such as topography, land use, etc. should be considered in modeling.

Drought and dust are some of the atmospheric hazards that have affected the western and southwestern regions of the country for many years due to various factors. The recent droughts have had a significant impact on the emergence and intensification of dust. Therefore, studies related to it are considered important. In the current study, temporal and spatial fluctuations of meteorological drought and dust in Khuzestan province were examined on a monthly, seasonal and annual time scale. Drought estimation was possible using standard precipitation-evapotranspiration index (SPEI) and estimation of dust occurrence based on phenomenon codes 07 and 09 with a field of view of less than one kilometer. To ensure the adaptation of drought to the abundance of dust, a Pearson correlation was established between the two phenomena. The results of correlation showed a direct and significant relationship between meteorological drought and the number of dusty days in the province. The most correlation is in February, July, June, August, and May. The highest level of significance is attributed to the winter and summer and then spring. Cross-correlation also showed that the events of the dust simultaneously and one month later are more affected by the drought.

Assessment of metals absorbed to suspended solids in urban floods, allows managers to take measures to improve the quality of the urban environment. This article examines the changes in the concentration of heavy metals such as lead, zinc and copper in suspended load of runoff from the Bojnourd urban watershed in autumn and spring seasons. For this reason, 52 samples were collected. After preparing the samples, separation of suspended sediment using the Whatman filter paper and then weighing the amount of sediment in runoff, using atomic absorption, the amount of heavy metals dissolved in runoff and heavy metals absorbed to suspended solids in runoff were measured in terms of ppb. The results showed that the amount of suspended sediment weight is higher in spring than autumn. Results indicated that the maximum concentration of insoluble heavy metals and attached to sediments is more than soluble heavy metals in runoff. On the other hand, the results revealed that the mean maximum concentration of zinc and copper, except lead attached to sediments, is higher in the spring than autumn and the spatial concentration of zinc and copper in samples of runoff suspended sediments from Sandalabad Stream (FC3S) is higher. While on the lead, concentration for the samples taken from the runoff pathways and drainage network (FB2S) was higher. However, the difference in location of data for heavy metals absorbed to suspended sediments is not statistically significant. The Pearson correlation test results showed that there is a positive but low correlation between lead and zinc (r =0.166) in the autumn and the lead and copper (r=0.271) in the spring. Significance of this correlation is certified using hierarchical cluster analysis method.

Drought is one of the known environmental phenomenon and impartible part of change climate that occurs in each geographic region. In this study was used Standardized Precipitation Index (SPI) and streamflow drought index (SDI) for assessment and analysis of droughts incidence temporal. For this purpose, were used monthly statistics of 10 rain gauge and 5 hydrometric stations in Karkheh watershed and indicators investigated in 3 timeframes (12, 24, 48 months). At the first, relationship of precipitation and runoff investigated for drought effect study on surface water resources. Then the standardized data rate (SDI) with SPI time series at varies temporal interval using Pearson correlation was studied in the whole of basin and sub basin also compared separately. The results showed that temporal relationship of hydrological and meteorological drought occurrence is meaningful in level of 99 % with together and this correlation is maximum in 48 months. Drought occurrence in case study showed its effect on surface water resources with a delay of 2 months or 1 month that due to the karstic region.

Dust is one of the drought consequences which during recent years has been emerged as one of the important factors affecting wheat growth and its production yield beside other climatic fluxions. In this research, the drought intensity has been studied at nine synoptic stations of Lorestan province, during a ten years period of 2000-2009 and its dominant effects on dust frequency rate and its effects during seasons on the wheat cultivation performance rate, as one of the most important agricultural products sensitive to climatic variations,. The drought intensity analysis has been conducted by SPI index, for a six months’ time scales led to January and its relation with dusty day’s frequency distribution has been examined in horizontal sight less than 2000 m at the province stations. Also, the mutual correlation rates have been analysed using Pearson correlation test and multiple regression method with SPSS software and clustering was studied using Ward method in S-plus software. Results demonstrated that even during normal wet-spell, dust days happen and wheat performance in drylands falls below1000 kg ha-1 (2004, 2005 and 2007). Whereas, the dust days reached to zero and the wheat performance exceeded kg ha-1 (2006), when the wet-spell exceeds its normal rate and reaches to reduced domain. The frequency of dust days and wheat performance are directly correlated in most stations like Khoramabad, Koohdasht and Broojerd with a rate of 0.784, 0.626 and 0.933, respectively and completely adverse in Azna with a rate of -0.926.

Drought is a natural and recurring phenomenon which causes water scarcity in various sectors. In comparison with other natural hazards and disasters, drought is more important considering intensity and frequency as well as spatial extent and total damage. In the current research, the Standardized Precipitation Index (SPI) and Standardized Discharge Index (SDI) were used to analyze the temporal characteristics of droughts. To this end, monthly precipitation time series of 23 raingauge stations and 7 hydrometry stations across the Atrak River basin were used and SPI and SDI for six time intervals (3, 6, 9, 12, 24 and 48 months) were calculated and analyzed. For assessment of drought impact on surface water resources, first the correlation between rain and discharge time series of different lag times were calculated within the study area. Then, the Pearson correlation method was applied to calculate the correlation between SDI and SPI series for different time intervals at each individual subwatershed and whole watershed of the Atrak River. The results showed that the correlation between meteorological and hydrological droughts was significant at 99 percent confidence level. The maximum correlation was found for SPI and SDI of 3 months time intervals. This indicates that droughts cause decrease in surface flows and this impact is remarkably observed in the discharge values of the same month or one month later. The highest Pearson correlation was found for the Shirabad station and the Darband subwatershed.