mohammad ekrami; Rasool Mahdavi Najaf abadi; Marzieh Rezai; hassan vagharfard; Jalal Barkhordari
Abstract
In recent decades, among natural disasters, the frequency of agricultural drought has been higher than other natural disasters. The best way to management of agricultural drought was to management drought-stricken society. The purpose of this study was to assess the vulnerability and spatial analysis ...
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In recent decades, among natural disasters, the frequency of agricultural drought has been higher than other natural disasters. The best way to management of agricultural drought was to management drought-stricken society. The purpose of this study was to assess the vulnerability and spatial analysis of drought in Pishkuh watershed in Yazd province. the effective parameters in the vulnerability of agricultural drought in the region became information layers, and after weighting the layers in terms of the importance of agricultural drought vulnerability in the framework of multi-criteria decision making (MCDM) Agricultural drought in the study area was prepared. In order to control, monitoring and evaluation the final map, field studies of the study area were also used. The results showed that the highest weight of the effective parameters in drought vulnerability was related to the precipitation parameter, the value of which is equal to 0.31, and the lowest weight was related to the slope parameter with a value of 0.05. According to the obtained results, the most vulnerable agricultural droughts were related to Sanich, Darashir, Darasir, Eshkaft, Morok, etc. Geomorphologically, these areas were considered to be high and mountainous, more severe than plain areas due to the low depth of sediments, coarse-grained soil texture and aquatic resources (Qanats), mainly their vulnerability to drought, and In terms of time, they suffer more quickly, in other words, they suffer a lot of damage in the short term. While areas such as Islamia, Nasrabad, Mazrea Akhund, Hemmatabad , etc. were in a lower degree of agricultural drought damage. The results indicate that the degree of damage to agricultural drought estimated in the final map is in line with the findings of field studies. Therefore, the map of agricultural drought vulnerability has acceptable and desirable accuracy.
Ahmad Nohegar; Mohammad Kazemi; Seyed Javad Ahmadi; Hamid Gholami; Rasool Mahdavi
Abstract
Efficiency of sediment fingerprinting by using tracers as a successful method to determine the sources of sediment has been proved. Selection of the suite subset of tracers, capable of discriminating sediment sources, is the first and the most important step in the sediment fingerprinting method. The ...
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Efficiency of sediment fingerprinting by using tracers as a successful method to determine the sources of sediment has been proved. Selection of the suite subset of tracers, capable of discriminating sediment sources, is the first and the most important step in the sediment fingerprinting method. The presence of outliers affects the selection of the suite subset and possibly prevents picking the important tracers and reducing the accuracy of classification. Therefore, the outliers must be detected in order to be corrected or omitted, if enough evidences were present. The present study aims to detect outliers in the subset of tracers, to identify the best combination. For detecting outliers, We used univariate methods such as Grubbs test, Gauss test, Dioxin test, box plot, the Median ± 3MAD, the mean ± 3standard deviation and also multivariate methods such as squared Mahalanobis distance, separate box plots of squared Mahalanobis distance for each of sediment sources, principal component analysis and plot of the squared Mahalanobis distances against the quantiles of the chi-square distribution. we consider an observation as the outlier that at least half of these methods have detected it as an outlier. The results showed that Median ± 3MAD method introduced a larger number of data as outliers Methods of multivariate outlier detection has low agreement with each other. Univariate methods to identify outliers show higher agreement with each other. To use univariate analysis techniques to detect outliers namely Median ± 3MAD, box plot, and Dioxin one can recommended to test their sensitivity. The results also showed that the maximum consensus for univariate analysis techniques is four samples (observations) and for multivariate methods is two samples (observations). In general, there is no observation that is identified as an outlier by half of the used methods.
