Variographic analysis of chemical and piezometric data from the sandstone aquifer of Ain Oussera, Algeria

The perturbation of piezometric level and the bad water quality in Ain Oussera plain represents a serious problem for local authorities and water resources managers. The spatial distribution of piezometric level and chemical data was analyzed by applying geostatistical methods, which provide an indication of the uncertainty of the estimation using the computer software VARIOWIN 2.2 (Pannatier 1996). In this paper, the evolution of the piezometric level and hydrochemical data by referring to other research campaigns was studied. Two campaigns were chosen; September 2001 and May 2008 for pizometric level and 1994 and 2004 for chemical data. In the beginning, elementary statistics has been carried out to understand the statistical distribution and performed an analysis of variance for comparison between two campaigns. Geostatistics for modeling and cartography were applied. The results showed that piezometric levels admit spherical model that the direction of groundwater flow is from southwest to northeast. High nugget effect characterizes piezometric data and chemical data, linked to the presence of microregions due to excessive pumping and local evaporitics formations. Anisotropy is observed in the northeast-southeast direction from which a spatial continuity in this direction can be deduced.     

An evaluation of various data pre-processing techniques with machine learning models for water level prediction

Natural Hazards - Floods are the most frequent type of natural disaster. It destroys wildlife habitat, damages bridges, railways, roads, properties, and puts millions of people at risk. As such,...     

The Tadjena Earthquake (Mw = 5.0) of December 16, 2006 in the Cheliff Region (Northern Algeria): Waveform Modelling,Regional Stresses,and Relation with the Boukadir Fault

The Cheliff region has experienced some significant earthquakes in the last century (1937, 1954, and 1980). The most destructive one is that of El Asnam on October 10, 1980, Ms = 7.3 (Io = IX), which destroyed the Chlef city (formerly El Asnam) and its surrounding villages. On December 16, 2006 a moderate earthquake (Mw = 5.0) hit the Cheliff region. The maximum observed intensity (Io = V: MSK-scale) was observed at Abou El Hassen, Benaria, Bouzghaïa and Tadjena. No damages or human losses were recorded. Nevertheless, minor cracks on walls of the old school at Tadjena were observed. The point source focal mechanism of the event was determined by inverting the waveforms of three regional broadband stations of the ADSN (Algerian Digital Seismic Network). It corresponds to thrust-reverse faulting with a strike-slip component. The stress tensor obtained by the inversion of the 15 focal mechanisms available in the Cheliff region exhibits a well constrained compression axis σ1 horizontal and trending N145°. The NW dipping nodal plane indicating a NE–SW thrust fault with a right-lateral component (strike, dip, rake = 249, 38, 137) is more compatible with the regional stress tensor than the steep dipping NNE-SSW nodal plane showing reverse faulting with a left-lateral component (strike, dip, rake = 15, 65, 60). Accordingly, the Tadjena moderate size earthquake can be related to the Boukadir active fault bordering the lower Cheliff basin to the north, a situation similar to that of the El Asnam fault bordering the middle Cheliff basin to the north.