1. Desertification simulation using wavelet and box-jenkins time series analysis based on TGSI and albedo remote sensing indices.
- Author
-
Hashem Geloogerdi, Sareh, Vali, Abbasali, and Sharifi, Mohammad Reza
- Subjects
- *
DESERTIFICATION , *AUTOCORRELATION (Statistics) , *TIME series analysis , *REMOTE sensing , *ALBEDO , *BOX-Jenkins forecasting , *ARID regions - Abstract
Desertification has been listed as one of the most critical global environmental issues, posing a significant threat to life, particularly in arid and semiarid regions. Therefore, gaining a comprehensive understanding of the present and future desertification trends becomes imperative. This study employs a feature space model, which effectively captures land surface changes related to desertification, enabling the extraction of pertinent information. Subsequently, time series models are used to determine the most accurate desertification simulation. Twenty-one ETM + sensor images were utilized to calculate the Topsoil Grain Size (TGSI) and Albedo remotely sensed indexes. Constructing the Albedo-TGSI feature space, the Desertification Degree Index (DDI) was extracted for each year. Different levels of desertification were identified by applying a natural break classification on the DDI values, and corresponding break values were obtained. The representative desertification degree for each year was determined by calculating the average of the minimum and maximum break values, resulting in the generation of five distinct time series for five desertification degrees. Different ARIMA models and wavelet transforms were selected to simulate the various desertification degrees based on the analysis of autocorrelation and partial autocorrelation functions and trial and error, respectively. The most suitable ARIMA models with the lowest errors were identified as follows: ARIMA (1,0,7) for severe desertification, ARIMA (0,1,6) for high desertification, ARIMA (0,0,7) for moderate desertification, and ARIMA (3,0,6) for non-desertification degrees. Among the various wavelet transform families tested, the Symlet family proved to be the most effective, except for the low desertification degree. The following wavelet transforms yielded the best results for each degree of desertification: Symlet3 for severe desertification, Symlet7 for high desertification, Symlet7 for moderate desertification, Daubechies 5 (db5) for low desertification, and Symlet7 for non-desertification degree simulations, all exhibiting the minimum error rates. • For 21 images (1994–2019 ETM + remotely sensed images): • Topsoil grain size and Albedo indexes were calculated and extracted; Then Desertification Degree Index was calculated each year. • A natural break classification was applied to divide DDI into five desertification degrees. • DDI time series were generated using the average break values of each degree. • The best ARIMA models based on autocorrelation and autocorrelation functions and the most suitable wavelet transforms were identified through trial and error. • The best ARIMA models and wavelet transforms were chosen for desertification simulation through the validation step. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF