DAMNATI BRAHIM

Restricted Boltzmann Machines are generative models which can be used as standalone feature extractors, or as a parameter initialization for deeper models. Typically, these models are trained using Contrastive Divergence algorithm, an approximation of the stochastic gradient descent method. In this paper, we aim at speeding up the convergence of the learning procedure by applying the momentum method and the Nesterov’s accelerated gradient technique. We evaluate these two techniques empirically using the image dataset MNIST.

Abstract The study area is located in Chott Baghdad (northern the Hedjira village) from the Wilaya of Ouargla, in the northeastern Algerian Sahara. The succession shows at the bottom an alternating of gypsiferous clay-sandstone layers, demonstrating some hydrodynamic sedimentary structures such across stratifications, escape structures, and continental trace fossils. The clay facies contains, some lacustrine microfossils specially foraminifera and ostracods. The uppermost of the succession is characterized by the presence of surrounded pebbles embedded in clay-sandstone matrix, overlain by gypseous-carbonate crust, showing on the top surface mud cracks. The granulometry and morphoscopy analysis evidence round-matt to lustrous blunt of quartz grain. Those data together with the fauna content and sedimentary structures indicate that the paleoenvironment should correspond to fluvio-lacustrine, under wind and torrential phases, linked to temporary climate change.

Lake level fluctuations are one of the most important sources of palaeohydrological and palaeoclimatic information for continental areas over the late Quaternary. We have compiled old and new published lake status data from North African basins, over tree periods: between 30,000 and 21,000 yr B.P, ca 9,000 yr B.P and ca 6,000 yr B.P. Between 30,000 and 21,000 yr B.P, one or two relatively humid episodes have been identified in northern hemisphere of Africa. However, at 21,000 yr B.P, Low or intermediate lake status was registered in the Sahara, in west and east Africa north equator. The scarcity of data in this period globally reflects severe desiccation, deflation and erosion in many basins. It's clear that the late glacial maximum was significantly dry in this area. At 9,000 yr B.P, many lakes began to rise. Some of them receded dramatically after 11,000 yr B.P. The majority of lakes with this initial amelioration was in north-east Africa in equatorial zone. The large perturba...

Abstract In the Moroccan Middle Atlas Mountains, three lakes were used to characterize climate variability in the late Holocene. The methodology is based on sedimentological, geochemical, and mineralogical analysis of lacustrine terraces. Lake Ifrah is a natural lake. Waters are calc-magnesian, relatively very alkaline and oxygenated. Lake Afourgagh is of karst origin, with maximum depth 1.5 m. Lake Iffer is a smaller lake, sub-circular and relatively deep. Its area is 3.5 ha. Its maximum depth is 6.5 m at the center of the lake. Seven terraces located in the borders of the lakes were sampled and studied. Seven radiocarbon dates were obtained on organic matter and shells. The time period concerned is between 2300 cal BP and 400 cal BP. The results show high lake levels at about 2300 cal BP related probably to the wetter Iberian – Roman period in northern Mediterranean. Lake Iffer was deeper by about 30 m from its current level. 1000 cal BP probably marks the beginning of the decline with a drop in lake level of 20 m, which is ongoing in connection with drier climate and the beginning of the medieval climate anomaly.

Soil erosion is becoming acute in northern Morocco. It recognized
as the most dangerous form of land degradation, which causes serious environmental
problems, for agriculture, for road infrastructure and for dams.
A quantitative identification of potentially most erodible areas, associated
with a spatial and temporal distribution of erosion rates remain a necessity, to
optimize the means implemented to combat this phenomenon. It is in this
context that the use of mathematical models and computer systems are of
growing importance.
The purpose of this research was to study the capabilities of SWAT to simulate
land losses in the watersheds of northwestern Morocco.
The land, on which the model is implemented, is El Hachef watershed.
SWAT model performance, as well as the dynamics and spatial disparities of
soil losses at the watershed scale are illustrated and discussed.
The simulation of the earth loss, at a daily time step, over the period from
1959 to 2011 shows that the average annual rate of soil erosion in the El Hachef
watershed is 26.65 t/ha/yr. It also made it possible to describe the spatial and
temporal variation of the quantities of sediments transported by runoff, at the
watershed level. The highest rates exceeding 50 t/ha/yr are recorded in the subwatersheds
located in the northeast part of the watershed.
This initiative makes it possible to accomplish a realistic soil loss modeling in
El Hachef watershed, and highlights the performance of the tool for different
processes.

While the paleofire activity of the Late Glacial Maximum is well defined in different records from most part of the both hemispheres, paleofire activity in North Africa and its connections with past climatic changes still remains poorly documented. A multiproxy analysis using organic and inorganic matter, geochemistry, magnetic susceptibility, microcharcoal and pollen data from Lake Ifrah (Middle Atlas - Morocco) provides new insights for better understanding paleofire occurrence during the Late Glacial Maximum and Holocene periods. The comparison between microcharcoal distribution and lacustrine multiproxy data highlights the variability of paleofire activity that is interpreted in term of long-term climate-driven changes. The early- to mid-Holocene (between 10.2 and 5.0 k yr BP) marked a significant increase in microcharcoal abundance which likely testifies regional emissions from forest fires. Such biomass burning events were associated to prolonged periods of drought, as inferre...

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract The study area is located in Chott Baghdad (northern the Hedjira village) from the Wilaya of Ouargla, in the northeastern Algerian Sahara. The succession shows at the bottom an alternating of gypsiferous clay-sandstone layers, demonstrating some hydrodynamic sedimentary structures such across stratifications, escape structures, and continental trace fossils. The clay facies contains, some lacustrine microfossils specially foraminifera and ostracods. The uppermost of the succession is characterized by the presence of surrounded pebbles embedded in clay-sandstone matrix, overlain by gypseous-carbonate crust, showing on the top surface mud cracks. The granulometry and morphoscopy analysis evidence round-matt to lustrous blunt of quartz grain. Those data together with the fauna content and sedimentary structures indicate that the paleoenvironment should correspond to fluvio-lacustrine, under wind and torrential phases, linked to temporary climate change. Abstract The study area is located in Chott Baghdad (northern the Hedjira village) from the Wilaya of Ouargla, in the northeastern Algerian Sahara. The succession shows at the bottom an alternating of gypsiferous clay-sandstone layers, demonstrating some hydrodynamic sedimentary structures such across stratifications, escape structures, and continental trace fossils. The clay facies contains, some lacustrine microfossils specially foraminifera and ostracods. The uppermost of the succession is characterized by the presence of surrounded pebbles embedded in clay-sandstone matrix, overlain by gypseous-carbonate crust, showing on the top surface mud cracks. The granulometry and morphoscopy analysis evidence round-matt to lustrous blunt of quartz grain. Those data together with the fauna content and sedimentary structures indicate that the paleoenvironment should correspond to fluvio-lacustrine, under wind and torrential phases, linked to temporary climate change.

A B S T R A C T The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. Deserts and marine aerosols combine with combustion aerosols from maritime traffic, large urban centers, and at a larger scale from populated industrialized regions in Europe. From Tetouan city located in the North of Morocco, we attempted to better figure out the main aerosol transport pathways and their respective aerosol load and chemical profile by examining air mass back trajectory patterns and aerosol chemical compositions from May 2011 to April 2012. The back trajectory analysis throughout the sampling period led to four clusters, for which meteorological conditions and aerosol chemical characteristics have been investigated. The most frequent cluster (CL3: 39%) corresponds to polluted air masses coming from the Mediterranean Basin, characterized by urban and marine vessels emissions out of Spain and of Northern Africa. Two other polluted clusters were characterized. One is of local origin (CL1: 22%), with a marked contribution from urban aerosols (Rabat, Casablanca) and from biomass burning aerosols. The second (CL2: 32%) defines air masses from the near Atlantic Ocean, affected by pollutants emitted from the Iberian coast. A fourth cluster (CL4: 7%) is characterized by rather clean, fast and rainy oceanic air masses, influenced during their last 24 h before reaching Tetouan by similar sources with those affecting CL2, but to a lesser extent. The chemical data show that carbonaceous species are found in the fine aerosols fraction and are generally from local primary sources (low OC/EC) rather than long-range transported. In addition to fresh traffic and maritime vessel aerosols, our results suggest the contribution of local biomass burning.

RÉSUMÉ Les paléofeux en relation avec les changements climatiques passés en Afrique du Nord restent encore mal documentés. Une étude multidisciplinaire utilisant la minéralogie, la géochimie et les traces du feu (microcharbon) sur des sédiments du lac Ifrah (Moyen Atlas, Maroc) offre de nouvelles perspectives pour une meilleure compréhension des variations climatiques depuis le dernier maximum glaciaire à nos jours. Depuis 24 000 jusqu'à 13 000 ans cal. BP, la concentration des sédiments en microcharbons était très faible, en lien avec une faible activité de feu et un climat froid. La phase comprise entre 13 000 et 10 800 ans cal. BP est une période de transition. Le début de l'Holocène moyen (entre 10 800 et 4 500 ans cal. BP) se caractérise par une forte augmentation de la concentration de particules de microcharbons. Un pic de ces particules est observé à 107 cm (soit 8 200 ans cal. BP). Cette phase est marquée par une forte activité des feux au cours d'une période sèche. L'Holocène supérieur (entre 4 500 et 1 700 ans cal. BP) marque le retour à des conditions climatiques humides manifestées essentiellement par une baisse modérée de la concentration de particules de microcharbons. ABSTRACT MICROCHARCOAL IN MIDDLE ATLAS IFRAH LAKE SEDIMENTS (MOROCCO) : CLIMATE SIGNIFICANCE FOR THE LAST 24,000 CAL. YRS BP The microcharcoal study related to past climate change in North Africa remains poorly documented. A multidisciplinary study using mineralogy, geochemistry and traces of fire (microcharcoal) at Ifrah lake sediments (Middle Atlas, Morocco) offers new perspectives for a better understanding of climate change since the last glacial maximum to the present. From 24,000 to 13,000 cal. yrs BP, the microcharcoal concentration was very low in conjunction with a low fire activity and a cold climate. The phase between 13,000 and 10,800 cal. yrs BP is a period of transition. The beginning of the middle Holocene (between 10,800 and 4500 cal. yrs BP) is characterized by an increase in the concentration of microcharcoal particles. A peak of the particles is observed at 107 cm (ca 8200 cal. yrs BP). This phase is marked by a strong fire activity during a dry period. The upper Holocene (between 4500 and 1700 cal. yrs BP) marks the return of wet climatic conditions showed by a moderate decrease in the concentration of microcharcoal particles.

In the Moroccan Middle Atlas Mountains, three lakes were used to characterize climate variability in the late Holocene. The methodology is based on sedimentological, geochemical, and mineralogical analysis of lacustrine terraces. Lake Ifrah is a natural lake. Waters are calc-magnesian, relatively very alkaline and oxygenated. Lake Afourgagh is of karst origin, with maximum depth 1.5 m. Lake Iffer is a smaller lake, sub-circular and relatively deep. Its area is 3.5 ha. Its maximum depth is 6.5 m at the center of the lake. Seven terraces located in the borders of the lakes were sampled and studied. Seven radiocarbon dates were obtained on organic matter and shells. The time period concerned is between 2300 cal BP and 400 cal BP. The results show high lake levels at about 2300 cal BP related probably to the wetter Iberian e Roman period in northern Mediterranean. Lake Iffer was deeper by about 30 m from its current level. 1000 cal BP probably marks the beginning of the decline with a drop in lake level of 20 m, which is ongoing in connection with drier climate and the beginning of the medieval climate anomaly.

Lake level fluctuations are one of the most important sources of palaeohydrological and palaeoclimatic information for
continental areas over the late Quaternary. We have compiled old and new published lake status data from North African
basins, over tree periods: between 30,000 and 21,000 yr B.P, ca 9,000 yr B.P and ca 6,000 yr B.P.
Between 30,000 and 21,000 yr B.P, one or two relatively humid episodes have been identified in northern hemisphere of
Africa. However, at 21,000 yr B.P, Low or intermediate lake status was registered in the Sahara, in west and east Africa
north equator. The scarcity of data in this period globally reflects severe desiccation, deflation and erosion in many basins.
It’s clear that the late glacial maximum was significantly dry in this area.
At 9,000 yr B.P, many lakes began to rise. Some of them receded dramatically after 11,000 yr B.P. The majority of lakes
with this initial amelioration was in north-east Africa in equatorial zone. The large perturbation is occurred in northern
Africa. Between 0° and 22°N, nearly all lakes were high. The water status responded first near the equator (between 0° and
10°N) and subsequently rises progressively in Sahara and Sahel. The main period of positive hydrological conditions was
recorded simultaneously in lacustrine systems in interdunal depression and in Sebkhas in Mauritania, Mali, Eastern Niger
and Sudan.
At 6,000 yr B.P, the lakes show a more positive water balance over northern Africa. The southern margin of the zone of
wetter conditions is unchanged relative to 9,000 yr B.P, but evidence from two sites in the Libyan desert suggests that the
northern boundary may have been slightly further north. There is a suggestion that conditions became wetter than 9,000 yr
B.P (and today) in the Maghreb.
Keywords: Climate, Lakes, data, Africa northern Hemisphere, last glacial maximum, Holocene

Measurements of soil erosion on the Moroccan landscape using classical erosion methods
have been the main objective of several research studies. These classical methods are very difficult,
time consuming and very expensive. The quantitative estimation of soil loss remains insufficient
particularly in the North of Morocco. In this study, we present results showing the quantification of
the soil erosion using 137Cs and 212Pb in two dam catchments: Raouz and Nakhla.
In the Raouz catchment, the inventories of 137Cs vary between 574 Bq/m2 and 3422 Bq/m2
and of 210Pbexc vary between 274 Bq/m² and 2704 Bq/m². In the second study area situated in the
drainage basin of the Nakhla dam the mean inventories of 137Cs consist between 426 and 777 Bq/m2,
while the mean inventories of 210Pbexc vary between 580 and 891 Bq/m².
The conversion of the inventories in terms of erosion rate and/or accumulation has been done using
a mass balance model (1 and 2) and the 210Pbexc model. The mean erosion rates are respectively
between 8 and 14 t.ha-1.yr-1 and between 18 and 41 t.ha-1.yr-1 using 137Cs models. Using 210Pbexc
model, the mean erosion rate it’s about 20 t.ha-1.yr-1.
These results show the severity of erosion in North West Morocco and the necessity to seek for
urgent and appropriate solutions to stop this problem

L’étude du climat ancien permet de comprendre les mécanismes des changements naturels du climat planétaire et d’en déduire les principales rétroactions.
Le climat marocain variait naturellement au cours de l’histoire de la Terre. Il a fait très froid il y a plus de 21000 ans avant le présent et il a fait chaud pendant l’Holocène et surtout vers 8000 ans avant le présent. Ces changements climatiques qu’a connus le Maroc étaient relativement synchrones avec les changements climatiques globaux. Pendant les trois derniers siècles, plusieurs périodes de sécheresse ont été mises en évidence par l’étude des cernes d’arbre et des documents historiques.
Actuellement le climat se réchauffe. Les scientifiques sont unanimes, les activités humaines sont responsables de cet emballement du climat. Au Maroc, comme dans plusieurs pays du monde, les impacts de ces changements climatiques seront plus au moins catastrophiques. Une vigilance s’impose pour une meilleure adaptation.
Ce livre est destiné aux enseignants chercheurs, aux décideurs, aux étudiants et à ceux qui s’intéressent aux changements climatiques dans le monde et particulièrement au Maroc. Il s’agit d’une étude synthétique des travaux de recherche inédits ou publiés récemment dans ce domaine.