Diachronic analysis of salt-affected areas using remote sensing techniques: the case study of Biskra area, Algeria

Abstract

In the Wadi Biskra arid and semi-Arid area, sustainable development is limited by land degradation, such as secondary salinization of soils. As an important high quality date production region of Algeria, it needs continuous monitoring of desertification indicators, since the bio-physical setting defines it as highly exposed to climate-related risks. For this particular study, for which little ground truth data was possible to acquire, we set up an assessment of appropriate methods for the identification and change detection of salt-Affected areas, involving image interpretation and processing techniques employing Landsat imagery. After a first phase consisting of a visual interpretation study of the land cover types, two automated classification approaches were proposed and applied for this specific study: decision tree classification and principal components analysis (PCA) of Knepper ratios. Five of the indices employed in the Decision Tree construction were set up within the current study, among which we propose a salinity index (SMI) for the extraction of highly saline areas. The results of the 1984 to 2014 diachronic analysis of salt-affected areas variation were supported by the interpreted land cover map for accuracy estimation. Connecting the outputs with auxiliary bio-physical and socio-economic data, comprehensive results are discussed, which were indispensable for the understanding of land degradation dynamics and vulnerability to desertification. One aspect that emerged was the fact that the expansion of agricultural land in the last three decades may have led and continue to contribute to a secondary salinization of soils. This study is part of the WADIS-MAR Demonstration Project, funded by the European Commission through the Sustainable Water Integrated Management (SWIM) Program (www.wadismar.eu)

Improving Land Cover Mapping: A Mobile Application Based on Esa Sentinel 2 Imagery

“…As discussed in previous studies, changes in land use in the study areas are very quick as they are linked to local climate conditions. Moreover, as in other countries soil salinization, deforestation and forest fires are very common and can modify the land use of local communities (Afrasinei et al, 2015(Afrasinei et al, , 2018. Data collected by the FLOWERED GeoDBapp will be available for the scientific community through a specific and dedicated web portal based on SHARE-GeoNetwork architecture (Melis et al 2013;Melis et al 2014;Mattavelli et al 2016) with the sharing of knowledge based on open data philosophy.…”

Application of spatial- and diachronic-process analysis of landscape development in Central Lika, Croatia from 1980 to 2012

“…A diachronic analysis (López-Estébanez et al 2012;Afrasinei et al 2015), generally involves comparing data for two time points. Apart from in landscape research, diachronic analysis is also ski trend, u odnosu na ostala naselja administrativnog područja Grada Gospića (Čukman, 2018), kao i periferne dijelove regije.…”

Classification methods for detecting and evaluating changes in desertification-related features in arid and semiarid environments

“…Common and acknowledged digital image classification methods, such as supervised, unsupervised, or spectral mixture, have been widely applied for the delineation of salt features, but no agreed-upon and replicable technique has been acknowledged to be optimal. The stateof-art reports problems regarding misclassification and spectral mix-up of salty features with other land cover types, especially urban features, bare land, and areas that have a high content of carbonate minerals (Khan et al 2005;Fares and Philip 2008;Elnaggar and Noller 2010;Afrasinei et al 2015a).…”