Search

The purpose of the present study was to compare the prediction performances of three statistical methods, namely, information value (IV), weight of evidence (WoE) and frequency ratio (FR), for landslide susceptibility mapping (LSM) at the east of Constantine region. A detailed landslide inventory of the study area with a total of 81 landslide locations was compiled from aerial photographs, satellite images and field surveys. This landslide inventory was randomly split into a testing dataset (70%) for training the models, and the remaining (30%) was used for validation purpose. Nine landslide-related factors such as slope gradient, slope aspect, elevation, distance to streams, lithology, distance to lineaments, precipitation, Normalized Difference Vegetation Index (NDVI) and stream density were used in the landslide susceptibility analyses. The inventory was adopted to analyse the spatial relationship between these landslide factors and landslide occurrences. Based on IV, WoE and FR approaches, three landslide susceptibility zonation maps were categorized, namely, “very high, high, moderate, low, and very low”. The results were compared and validated by computing area under Road the receiver operating characteristic (ROC) curve (AUC). From the statistics, it is noted that prediction scores of the FR, IV and WoE models are relatively similar with 73.32%, 73.95% and 79.07%, respectively. However, the map, obtained using the WoE technique, was experienced to be more suitable for the study area. Based on the results, the produced LSM can serve as a reference for planning and decision-making regarding the general use of the land.

In this research, a climatic synthesis was built to assess the climatic parameters of the Oued Souf Valley through the meteorological data obtained from Guemar station (airport). It was revealed that the hydrological year of Oued Souf Valley is branded by the presence of a dry period and the total absence of a wet period over the year, even during January, when it was observed to have the lowest temperature and highest precipitation, which classified it as a Saharan climate (Hyper arid). The irregularity and the scarcity of precipitation, high temperatures and extremely high evapotranspiration had significant repercussions on surface runoff and infiltration which implies a high pressure on the water resources of Oued Souf valley and may disrupt the future socioeconomic project and increase the damage of natural drought and desertification. [ABSTRACT FROM AUTHOR]

The natural salinization of Souf sandy Terminal Complex groundwater notably Pontian and Mio-Pliocene has increased four times for the last 30 years, because of over pumping for drinking and irrigation. Application of the statistical modelling using multivariate analysis, and the Water Quality Index, to evaluate the groundwater variables have been done for groundwater management, by the investigation of water samples collected from 25 boreholes, in May 2018. Cluster analysis identified three main water types based on the major ionic contents. Factor Analysis and Principal Component Analysis methods confirmed the cluster analysis results. The water groups have sodi-potassic facies which dominate in the western part of Souf, compared to the eastern part and they have poor quality. An osmosis phenomenon allowed the homogenization of Pontian and Mio-Pliocene groundwater. The contact of Terminal Complex with the Eocene dolomite and Senonian evaporitic host rocks allows introducing a new preferential dissolution corridors concept in which an underground leaching front occurs with the increased pumping. Overlying sandy rocks subsidence can be produced gradually with a rise in the static groundwater level because of the leached underground Senonian evaporitic rocks. Closure of wells intersecting the evaporitic layers and minimizing of pumping from Terminal Complex groundwater in the Southwest part of Souf is strongly recommended, and the groundwater is requiring treatment before supply. [ABSTRACT FROM AUTHOR]