Use of genetic algorithm in new approach to modeling of flood routing

The hydrological models and simpli?ed methods of Saint-venant equations are used extensively in hydrological modeling, in particular for the simulation of the ?ood routing. These models require speci?c and extensive data that usually makes the study of ?ood propagation an arduous practice. We present in this work a new model, based on a transfer function, this function is a function of parametric probability density, having a physical meaning with respect to the propagation of a hydrological signal. The inversion of the model is carried out by an optimization technique called Genetic Algorithm. It consists of evolving a population of parameters based primarily on genetic recombination operators and natural selection to?nd the minimum of an objective function that measures the distance between observed and simulated data. The precision of the simulations of the proposed model is compared with the response of the Hayami model and the applicability of the model is tested on a real case, the N'Fis basin river, located in the High Atlas Occidental, which presents elements that appear favorable to the study of the propagation. The results obtained are very satisfactory and the simulation of the proposed model is very close to the response of the Hayami model.     

The paranthurid isopod crustacean Paranthura nigropunctata (Lucas, 1846): first record from the Atlantic coast of Morocco

The littoral paranthurid isopod crustacean Paranthura nigropunctata (Lucas, 1846) is recorded for the first time from the littoral of El Jadida located on the Atlantic northwest coast of Morocco. Specimens were obtained from the invasive brown seaweed Sargassum muticum and the natives Bifurcaria bifurcata and Cystoseira tamariscifolia in January 2015. This new record further confirms a significant southward distribution of P. nigropunctata and contributes to the knowledge of the biogeography of this isopod. Heretofore, the species was only known from the western and eastern Mediterranean and some Atlantic coasts. The present finding is the first of the species from Moroccan Atlantic shores, and suggests that the species may also be present in other coastal localities from Morocco and Africa. Some data on morphology, ecology and spatial distribution of the species are provided.     

Optimizing the dataset size of a topo-bathymetric survey for Hammam Debagh Dam,Algeria

The capacity of water reservoirs may be considerably reduced by sediment transport and accumulation. This phenomenon may occur quickly in regions prone to erosion, such as Hammam Debagh Dam region in Algeria. For better management of water resources, it is important to estimate the volume of a reservoir by regular and frequent topo-bathymetric surveys. Topo-bathymetric surveys with a high point measurement density are expensive and time-consuming. To reduce this expense and to increase the frequency of topo-bathymetric surveys, it is required to optimize their size and density. The complete survey of the reservoir created by the Hammam Debagh Dam in Algeria was examined in comparison with 19 reduction subsets using geostatistics. The study showed that the complete dataset of 32,164 points, corresponding to a density of 42 points ha^-1 could be reduced to 10,000 points, i.e. 13 points ha^-1, without affecting the estimation of the water volume in the reservoir. This reduction could considerably simplify the work load, reduce the expenses to do these surveys, and, therefore, allow for an increased frequency of topo-bathymetric surveys.     

Proposal of an empirical site classification method based on target simulated horizontal over vertical spectral ratio

Nowadays, most of the site classifications schemes are based on the predominant period of the site as determined from the average horizontal to vertical spectral ratios of seismic motion or microtremor. However, the difficulty lies in the identification of the predominant period in particular if the observed average response spectral ratio does not present a clear peak but rather a broadband amplification or multiple peaks. In this work, based on the Eurocode-8 (2004) site classification, and assuming bounded random fields for both shear and compression waves-velocities, damping coefficient, natural period and depth of soil profile, one propose a new site-classification approach, based on “target” simulated average \( H/V \) spectral ratios, defined for each soil class. Taking advantage of the relationship of Kawase et al. (Bull Seismol Soc Am 101:2001–2014, 2011), which link the \( H/V \) spectral ratio to the horizontal (\( HTF \)) over the vertical (\( VTF \)) transfer functions, statistics of \( H/V \) spectral ratio via deterministic visco-elastic seismic analysis using the wave propagation theory are computed for the 4 soil classes. The obtained results show that \( H/V \) and \( HTF \) have amplitudes and shapes remarkably different among the four soil classes and exhibit fundamental peaks in the period ranges remarkably similar. Moreover, the “target” simulated average \( H/V \) spectral ratios for the 4 soil classes are in good agreement with the experimental ones obtained by Zhao et al. (Bull Seismol Soc Am 96:914–925, 2006) from the abundant and reliable Japanese strong motions database Kik-net, Ghasemi et al. (Soil Dyn Earthq Eng 29:121–132, 2009) from the Iranian strong motion data, and Di Alessandro et al. (Bull Sesismol Soc Am 106:2, 2011.  https://doi.org/10.1785/0120110084) from the Italian strong motion data. In addition to the 4 EC-8 standard soil classes (A, B, C and D), the superposition of the 4 target \( H/V \) reveals 3 new boundary site classes; AB, BC and CD, for overlapping \( V_{s,30} \) ranges when the predominant peak is not clearly consistent with any of the 4 proposed classes. Finally, one proposes a site classification index based on the ratio between the cross-correlation and the mean quadratic error between the in situ \( H/V \) spectral ratio and the “target” one. In order to test the reliability of the proposed approach, data from 139 sites were used, 132 collected from the Kik-net network database from Japan and 7 from Algeria. The site classification success rate per site class are around 93, 82, 89 and 100% for rock, hard soil, medium soil and soft soil, respectively. Zhao et al. (2006) found an average success for the 4 classes of soil close to 60%, similar to what one found in the present study (63%) without considering the new soil classes, but much smaller if one considers them (86%). In the absence of \( V_{s,30} \) data, the proposed approach can be an alternative to site classification.     

Etude de l’évaporation de la nappe phréatique des zones arides: cas de Ouargla (Algérie)

La majorité des surfaces mises en valeur dans les zones arides et semi-arides de l’Algérie reposent sur des nappes phréatiques très minéralisées dont le niveau est proche de la surface du sol (0–1,5 m). En présence de conditions climatiques très sévères, le processus d’évaporation de ces nappes contribue en grande partie à la salinisation des terres et la dégradation du milieu. Les résultats de l’étude de l’évaporation de la nappe phréatique de la région de Ouargla montre que l’évaporation diminue au fur et à mesure que le niveau de la nappe s’éloigne de la surface du sol. L’évaporation de la nappe est maximale et égale à l’évaporation du plan d’eau lorsque le niveau de cette nappe est situé dans la couche 0–0,6 m et devient minimale au dessous de 1,7 m. Pour une meilleure mise en valeur des terres et une production agricole élevée, il est nécessaire de connaître la profondeur critique de la nappe phréatique, profondeur pour laquelle l’évaporation est faible et par conséquent le dépôt de sels est faible dans les sols à texture sableuse de la région aride de Ouargla.     

Application of structural equation modeling for assessing relationships between organic carbon and soil properties in semiarid Mediterranean region

Restoration of atmospheric carbon in soils has principal many good effects. Arid lands cover more than 40 % of the global earth area, but only stock 16 % from the global carbon stock. It seems to be a suitable solution for this environmental issue, but still all variables controlling organic carbon in such kinds of soil, was ignored. This study aims to develop two models of organic carbon under clayey and sandy soils in semi-arid Mediterranean zones basing on physical and chemical soil properties. For establishing both models, structural equation modeling was used. For modeling organic carbon, two Tunisian soil databases composed from clayey and sandy soils made respectively, of 450 and 602 soil horizons were used. Using the two databases for all properties, the principal component analysis shows two components for clayey soil; (i) chemical properties and bulk density and (ii) physical properties. For the sandy soil it reveals two components; (i) chemical properties and (ii) physical properties. According to the derived components for each soil category, two models have been built. Structural equation modeling results show that clayey model has proved that organic carbon was controlled by chemical properties and bulk density more than physical properties and sandy model has proved that organic carbon was controlled by chemical properties more than physical properties. The root mean square errors of approximation were 0.079 and 0.050 for the clayey and sandy models, respectively. Then these two models were validated with two other databases from Tunisian dryland soils.     

A laboratory study of the initial structure and the overconsolidation effects on the undrained monotonic behavior of sandy soil from Chlef region in northern Algeria

The effects of initial state of the samples and the overconsolidation ratio (OCR) on the behavior of Chlef sand were studied in this article. For this purpose, the results of two series of undrained monotonic triaxial compression tests on medium dense sand are presented. In the first test series, the influence of the specimen's fabric and confining pressure has been studied. The tests were conducted at initial confining pressure of 50, 100, and 200 kPa. Two methods of sample preparation, which included the dry funnel pluviation and the wet deposition, were utilized. All the samples were subjected to a monotonic loading after consolidation phase. The results of the tests demonstrate that an increase in initial confining pressure leads to an increase in the resistance to liquefaction. The results also show that the samples prepared with the dry funnel pluviation method exhibit a greater resistance to liquefaction than those prepared with the wet deposition method. In the second series of tests, the overconsolidation influence on the resistance to the sand liquefaction has been realized on samples at an effective stress of 100 kPa for OCR varying between 1 and 8. The tests show that the increase of OCR improves the stiffness of sand and accelerates the appearance of dilatancy.     

Delineation of potential recharge area using a hybrid model,case of Djelfa Hadjia watershed

Groundwater potential map is important for environmental assessment and water resources management. In this work, a groundwater recharge potential map was established for the watershed of Oued Djelfa Hadjia in Algeria, based on new multiparameters hybrid model. The model has hydroclimatic parameters, geological settings, slope factor, and stream network density factor as inputs. The groundwater recharge estimated by the model range from 0.71 to 14 mm. The model allows delineation of potential area of recharge. The total water abstraction in Djelfa city is about of 14 hm³; however, the calculated groundwater recharge is about 3 mm/year (min 0.71 mm and max 14 mm), which correspond to an average recharge volume of 3.9 hm³ which mean that the aquifer is under over exploitation.     

Factors driving the seasonal distribution of planktonic and epiphytic ciliates in a eutrophicated Mediterranean Lagoon

We studied the distribution of planktonic and epiphytic ciliates coupled with environmental factors and microalgae abundance at five stations in Ghar El Melh Lagoon (Tunisia). Planktonic ciliates were monitored for a year and epiphytic ciliates were sampled during summer 2011 in concordance with the proliferation of the seagrass Ruppia cirrhosa. Ciliate assemblage was largely dominated by Spirotrichea followed respectively by Tintinnida of and Strombidiida. No significant difference was found in the distribution of ciliate species among the stations. Redundancy analysis indicates that abiotic factors (temperature and nutriments) have a significant effect on the dynamics of certain ciliates. For epiphytic ciliates, 4 species were identified: Tintinnopsis campanula, Aspidisca sp., Strombidium acutum and Amphorides amphora. Based on PERMANOVA analyses, ciliates exhibit significant correlations among months and stations. According to ACP, epiphyte distribution follows roughly those of R. cirrhosa and pH. Significant correlations were found between harmful dinoflagellates and both planktonic and epiphytic ciliates.