spatial modeling
در نشریات گروه اکولوژی-
Aims
This study modeled sensitive areas to dust storms in Isfahan province, which is sensitive to successive droughts, and dust storms because of its climatic condition, and proximity to the desert, using meteorological codes related to dust, AOD values, and Maximum Entropy model (MaxEnt).
Materials & methods200 occurrence points of dust were determined using dust meteorological codes and AOD values of MODIS sensor, Terra satellite, (2011-2022). Ten parameters including temperature, rainfall, albedo, altitude, slope, land use, enhanced vegetation index (EVI), normalized difference moisture index (NDMI), normalized difference salinity index (NDSI), and frequency percentage of erosive wind seed were considered dust-predictive factors. Finally, the MaxEnt model was utilized for modeling dust susceptibility. The performance of the model was specified using the AUC value and the importance of each influential factor was identified utilizing the Jackknife test.
FindingsThe findings indicated that areas susceptible to dust are mainly bare lands, salt lands, and poor rangeland located mostly in the north, northeast to parts of the east and southeast of the Province, and also the central parts towards the southwest of Isfahan Province. According to the results, the MaxEnt model, with AUC=0.72, had a good efficiency in modeling susceptible areas to dust storms in Isfahan Province.
ConclusionThe major conclusion of this study is that the MaxEnt model had good performance in mapping susceptible areas to dust in Isfahan Province. The results of this research can be useful for decision-makers in identifying the areas prone to dust storms.
Keywords: AOD, dust storm, MaxEnt, spatial modeling, susceptibility -
Aims
In the present study, random forest (RF) and support vector machine (SVM) were used to assess the applicability of ensemble modeling in landslide susceptibility assessment across the Kolijan Rostaq Watershed in Mazandaran Province, Iran.
Materials & MethodsBoth models were used in two modeling modes: 1) A solitary use (i.e., SVM and RF) and 2) Their ensemble with a bivariate statistical model named the weights of evidence (WofE) which then generated two more models, namely SVM-WofE and RF-WofE. Further, the resulting maps of each stage were dually coupled using the weighted arithmetic mean operation and an intermodal blending of the previous stages.
FindingsAccuracy of the models was assessed via the receiver operating characteristic (ROC) curves based on which the goodness-of-fit of the SVM and the SVM-WofE models were 0.817 and 0.841, respectively, while their respective prediction accuracy values were found to be 0.848 and 0.825. The goodness-of-fit of the RF and the RF-WofE models respectively was 0.9 and 0.823, while their respective prediction accuracy values were found to be 0.886 and 0.823. The goodness-of-fit and prediction power of SVM and SVM-WofE ensemble were respectively 0.859 and 0.873. The same increasing pattern was evident for the ensemble of RF and RF-WofE where their goodness-of-fit and prediction power increased, respectively, up to 0.928 and 0.873. Moreover, the goodness-of-fit and prediction power of RF-SVM ensemble were increased up to 0.932 and 0.899, respectively. The results of the averaged Kappa values throughout a 10-fold cross-validation test as an auxiliary accuracy assessment attested to the same results obtained from the ROC curves.
ConclusionSuccessive intermodal ensembling approach is a simple and self-explanatory method so far as the context of many data mining techniques with a highly complex structure has been simply benefitted from the weighted averaging technique.
Keywords: Random Forest, Support Vector Machine, Spatial Modeling, Weights of Evidence -
بررسی تغییرات مکانی رسوب و عواملی که بر آن تاثیر می گذارد، برای کنترل آن امری ضروری است. در این پژوهش تغییرات مکانی ویژگی های تولید و غلظت رسوب طی آبراهه فصلی واقع در تیپ دشتسر فرسایشی بررسی شد. مکانیابی کرتها در فواصل 50 متری انجام و آزمایشها در 10 نقطه (با سه تکرار) اجرا شد. برای بررسی مقادیر رسوب تولیدی و غلظت آن، بارشی با شدت 4/1 میلیمتر در دقیقه و دوام 10 دقیقه توسط شبیهساز باران ایجاد و از مجاورت هر کرت، نمونه خاک سطحی برداشت شد. پس از انجام تحلیلهای آماری، با استفاده از روش کوکریجینگ، نقشه توزیع مکانی متغیرها تهیه شد. نتایج نشان داد بین غلظت رسوب 10 نقطه نمونهبرداری شده تفاوت معناداری وجود نداشت، اما بین مقادیر بار رسوب نقاط تفاوت معنادار مشاهده شد. نتایج برازش مدلهای تجربی بر نیمتغییرنماها نشان داد بهترین مدل برای ساختار مکانی غلظت رسوب، مدل گوسین و برای بار رسوب، مدل نمایی است و هر دو متغیر، ساختار مکانی خوبی دارند. نتایج اعتبارسنجی مدلها نیز نشان داد روش کوکریجینگ نقطهای، دقت کمی برای تخمین غلظت رسوب دارد، اما برای تخمین بار رسوبی، از دقت بیشتری برخوردار است.کلید واژگان: دانه بندی، درون یابی، دشت سر فرسایشی، مدل سازی مکانیStudy of the spatial variations of sediment and its influencing factors, is essential to control it. In this study, the spatial variations of production characteristics and sediment concentration in a seasonal stream located in an erosional pediment, studied. The location of plots at the 50 meters intervals selected and experiments done in 10 locations (with 3 replications). Then a rainfall with rainfall intensity of 1.4 mm/min and duration of 10 minutes, created using rainfall simulator and in the vicinity of each plot, surface soil samples were taken. The statistical analysis performed then using the cokriging method, the spatial distribution of characteristics prepared. The results showed that for sediment concentration variable among 10 locations, was no significant difference, but for the sediment load variable it was significant. The results of fitting experimental models on semivariograms, showed that the best fitted model to the spatial pattern of sediment concentration was gaussian and for sediment load was exponential model, respectively. Also two mentioned variables had strong spatial patterns. The results of the validation of applied model showed that the point-cokriging method has low accuracy to estimate sediment concentration, but for estimation of sediment load, the method has higher accuracy.Keywords: Erosional pediment, Granulometry, Interpolation, Spatial modeling
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