Journal of Spatial Analysis

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Nowadays, the adaptation of urban crisis management with  urban development plans is considered as an efficient way of cutting back on damages and it is essential to predict economic and physical susceptibility of families and communities. Therefore, considering the urban crisis index can play a significant role in urban planning. Tehran city thanks to geographic location, climate conditions and geological conditions is among risky cities so that the presence of seismic faults has made this city potentially seismic and in need of comprehensive crisis management; it needs to be confirmed that despite the earthquake potential in the region and the quality of the buildings especially in old and organic texture and other parameters such as access network and buildings and skeletal disorder the occurrence of a large scale earthquake and other natural disasters would be very catastrophic. For this purpose and given the high susceptibility of the region such as the impression by the North and South Rey fault, hazardous industries and fundamental establishments on the one hand and the presence of worn-out texture on the other hand were the reasons behind choosing this region to do the research.

     This research is descriptive-analytic in terms of data collection and practical concerning the function. The location of study is 20^th municipal district of Tehran. The area is about 23 square kilometer and by including the range  about 200 square kilometers. The research population consists of 500 experts and administrators engaged in preparation and practice of detailed municipal plan of Tehran city and crisis management organization of Tehran city. The research mass was selected at 217 persons by the use of Cochran’s formula. The sampling method was random classification method. Data collection instrument was the use of author-prepared questionnaire which consisted of four parts. Measurement instrument validity by facial method and its reliability was examined using  Chronbach Alpha. Therefore, after providing the required acceptable reliability among 20 persons of the subjects the personal attendance method of distribution was applied.

     The research findings show that among research variables, locating crisis management uses within detailed plans received more attention (Mean:82/36) and the knowledge of crisis management within detailed plan management process received less attention (Mean: 24/08). Also the study of distribution indices using  standard error deviation and variance reveals that the type of responses to the variable of attention to risky use policies (standard deviation: 4/08) has low distribution and attention to crisis management uses (8/49) has high distribution. For ranking variable conditions Freedman test was implemented. The results obtained from this test showed that the variable of attention to crisis management uses with the mean of 3/81 ranked first and attention to crisis management knowledge within detailed management process with the rank mean of 1/00 stands fourth on the list. The obtained results from the Pearson test also show that among all variables there is a significant relation with a confidence level of 99% and the correlation among them was  positive. Also the highest correlation coefficient was attention to the crisis management uses and attention to crisis management knowledge at the rate of 0/898 and the least correlation is about the relation between the variable of attention to knowledge of crisis management and the reflection of crisis management indexes on detailed project plans at the rate of 0/423.

     Considering the obtained results can conclude  that crisis management indexes through the process of preparation, approval and the administration of detailed projects of Tehran city and 20^th municipal district have not been attended sufficiently. For instance, skeletal features determination and operational properties at each urban scale were given the rate of susceptibility and the natural place limitations to enhance escape possibilities and people refuge (apposite building type, low building density, use of paths as the getaway and refuge spaces etc.) have not been estimated and their impacts have not been included in development plans.

     Also neighborhood was expected to be observed in urban lands use determination and avoid incongruous uses next to each other and provide quick exit but such cases have not been attended in detailed Tehran city project and 20^th municipal district or that the intended issues have been briefly listed and practically had no use in administration stage. In fact, the bad condition of the skeletal elements location and inapposite uses of the urban lands, deficient urban network, compact urban texture high urban density, improper location of fundamental establishments and shortage and improper distribution of urban open spaces etc. which have critical role in boosting up the rate of inflicted damages to Tehran city against crisis on the basis of the experts’ vantage point has received insufficient attention and while discussing the issue there is no coordination among related organizations concerning a serious attention to such indexes.

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The correct management in natural ecosystems is not possible without knowledge of the health in its sectors. Vegetation is the most significant sector in ecosystem that has important role in its health. Resilience is one of the defining features of health vegetation The term resilience was first introduced in the study of ecological systems and demonstrates the ability of the ecosystem to maintain its performance in the face of environmental disorders. A resilience-based system is not only equipped with a disorder adjustment mechanism but also has the potential to benefit from changes in a way that lead to creating an opportunity for development, innovation, and updating. Therefore, when a change occurs, the resilience provides the needed conditions for restarting and reorganization. If this goes beyond disturbing forces, the system will have the power to return to the maximum vegetation density with the least erosion effects, otherwise the system will be vulnerable to the change that was created and could already be controlled.
This research was done in part of North east of South Khorasan province (arid climate) with the aim of quantifying vegetative resilience on behalf of ecosystem health in response to drought occurrences and long-term precipitation changes, as environmental disturbances. Therefore first, using daily precipitation data from 15 meteorological stations around the study area, their annual precipitation was extracted and was standardized by Standard Precipitation Index (SPI) over the course of thirty years (1986 - 2015). Then, the SPI index data in 15 stations were interpolated by ArcGIS software based on Inverse Distance Weighted (IDW) method and dry, wet and normal years was estimated in the study region for each year. On the other hand, from archive of satellite images of Landsat 5 and Landsat 7, an image was created for each year in study period, between 15 June and 15 July, with permanent coverage at the best of growth. Following the necessary corrections for satellite images, the average Transformed Normalized Difference Vegetation Index (TNDVI) was obtained of each image by ENVI software. Finally, effected of precipitation changes on mean TNDVI was assessed and vegetation resilience was stabilized whit selected of sever time period samples based on four effective parameters (Amplitude, Malleability, Damping and Hysteresis).

Comparison of annual precipitation variations in the thirty-year time series (1986 -2015) indicated two approximate wet and dry periods in study area. The wet period is related to the first fourteen years of the time series (1986-1999) and the dry period is related to the last sixteen years (2000-2015). In this term, severe precipitation incidents with different intensities were occurred in the study area including one case of very intense precipitation (1986), one case of intense precipitation (1991) and two cases of moderate precipitation (1996 and 1992). Also, four drought incidents were occurred including one case of intense drought (2001) and three cases of moderate drought (1987, 2006 and 2008). All precipitations (wet years) are related to the first half and most droughts are related to the second half of the studied period. In this study for fixing of vegetation resilience in study area and for calculating of its parameters, In addition to the thirty-year time series selected sever time sections. in the whole study series (1986 - 2015), maximum of mean TNDVI (49.37 %) was in 1986 (reference), the lowest mean TNDVI (43.58%) was in 2010, The year effect of the decrease precipitation and drought, and mean TNDVI in 2015 was 44.28 %. Amount of parameters amplitude, malleability and damping are respectively 5.79, 0.7 and 5.09, and hysteresis was zero (%). The result of this case showed that the vegetation has moved towards the reference state (Resilience) but has not reached to amount of reference vegetation. The most specific cases for vegetation resilience happened from 1986 to 1996 (wet period) and 2003- 2009 time sector (dry period). In the first time section amount of amplitude and malleability were 0.64 %, damping was zero and hysteresis was 0.25%. The result of this case showed that not only the vegetation was returned to the reference state but also was increased to the reference (Cross reference).So despite the reduced rainfall and occurrence of sever occurrences of drought in dry period, hysteresis parameter (0.05 %) observed in 2003- 2009 time sector too that confirmed clearly vegetation health in study area whit dry climate. 

Awareness of the health status of the vegetation and its response to long-term precipitation changes and environmental disorders, such as drought occurrence, ensure the success of the managerial plans for renewable natural resources. The present study is the second study on quantifying the vegetation resilience and the first study under dry climatic conditions in Asia (an average annual precipitation of 160 mm) conducted in Iran by calculating four factors related to resilience, and is the first study that has presented the factor hysteresis in the calculations. Despite continuous of difficult condition, the native vegetation of the study area has been able to return the reference state not only by resolving the disorder relatively, but also it has experienced hysteresis stage. A set of quantitative calculations showed despite reduced annual precipitation and drought events, vegetation has been able to maintain its resilience, which indicates the health of the vegetation in the studied ecosystem. With the presence of such amazing protective and consistent mechanisms in the vegetation of arid regions, it is possible to maintain and restore these regions by proper managerial plans.

 

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Introduction
Dust storms as one of the environmental hazards of the arid regions of the globe, including the southern, southwestern, eastern and central parts of Iran, has caused many environmental problems that confirm the need for studying and crisis managing its in scientific and executive congresses. Therefore, the present study attempts to evaluate the effects of climate elements on temperature, precipitation, humidity, evapotranspiration and vegetation index on the frequency of dust storms in Yazd province during the period of 5 years (2009-2014).
 
Data and Methodology
So, after determining the synoptic stations of the area, the dust data were extracted based on the code of the present weather phenomena and the values of the climatic elements. In the next step, their spatial zonation was determined through the interpolation method. Then, using the MODIS images, EVI index data were calculated according to the principle of time matching. Finally, a variety of simple and multiple regression models were fitted to estimate the occurrence frequency of dust, and the most appropriate relationships with higher preference values were reported.
 
Findings and Conclusions
The results showed that there was a significant relationship between the total dust with evapotranspiration and relative humidity with a R square of 0.973 and 0.614 and the standard deviation of 24.104 and 92.477 at sig. level of 99% and 95%. Also, there is the maximum significant relation between external dust with evapotranspiration and relative humidity with a R square 0.968 and 0.621, and the standard deviation was estimated to be 0.173 and 75.427 at sig. level of 99% and 95%, respectively. Internal dusts with evapotranspiration and maximum temperature with a R square of 0.770 and 0.377 and standard deviation of 15.1751 and 64.22 have a significant relationship with sig. level of 95%. The results of the total, external and internal dust storms with climatic elements and vegetation cover showed a significant correlation with the R square of 0.994, 0.988 and 0.956 and the standard error of estimation of 18.13713, 24.2555551 and 10.49989 at sig. level of 99% and 95%, respectively, which indicates the systematic function of climatic elements and vegetation cover in the occurrence of dust.