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Le nord-ouest du Togo, est caracterise par une forte pression sur les sols, entrainant une regression de parcs agroforestiers et une diminution rendements agricoles. Dans un tel milieu, l’appreciation des producteurs de ces changements ainsi que les methodes qu’ils adoptent pour y faire face restent moins connus. C’est pour cet objectif qu’une enquete socio-economique a ete menee aupres des producteurs pour evaluer leurs perceptions sur la degradation des sols et les changements climatiques afin d’identifier puis retenir les pratiques originales d’adaptation pouvant faire objet de diffusion. L’enquete menee sur un echantillon raisonne de 216 producteurs des deux sexes a montre que : 98,10% des enquetes sont conscients de la degradation de leurs sols tandis que 99,50% ressentent les effets des changements climatiques qui se manifestent en termes de longues secheresses, de retards de pluies, de pluies violentes, abondantes et variable et d’augmentation de temperature. Les causes des changements evoquees par les producteurs sont : les pluies diluviennes (26,85%), les mauvaises pratiques culturales (62,50%), l’intensification agricole (46,76%), le surpâturage (2,78%), l’usage abusif de pesticides (20,37%), l’augmentation de la population (12,96%), la deforestation (21,76%) et les feux de brousse (6,48%). Globalement, les 98,6% des enquetes ont abandonne 63 ha de sol devenus irrecuperables. Les producteurs adoptent des mesures d’adaptation telles que l’apport de fumure organique, les rotations et associations culturales, la construction de bandes enherbees, de cordons pierreux et de diguettes, et le reboisement pour proteger et restaurer leurs champs. Plusieurs especes de plantes desirees par les producteurs pour leur vertu sont en voie de disparition. La perception par les paysans des cas de longue secheresse sont expliques par les variables « âge du paysan », « la pratique de l’elevage », « l’acces aux services de vulgarisation » et « la pratique de l’agriculture ». Il est necessaire de prendre ces variables en compte dans les projets et programmes de luttes contre la secheresse dans le milieu. Les variables « âge du paysan », « mauvaises pratiques culturales », et « deforestation » influencant egalement la perception des paysans de degradation des sols, doivent etre egalement consideres dans les programmes et projets de restauration des sols degrades dans le milieu. Il est important d’etudier les effets The north-west of Togo is characterized by strong pressure on the soil, leading to a decline in agroforestry parks and a reduction in agricultural yields. In such an environment, producers' appreciation of these changes and the methods they adopt to deal with them remain less well known. It is for this purpose that a socioeconomic survey was conducted among producers to assess their perceptions of soil degradation and climate change to identify and then retain original adaptation practices that can be disseminated. The survey carried out on a purposely selected sample of 216 producers from both sexes. The results showed that: 98, 10% of respondents are aware of the degradation of their soils while 99,50% feel the effects of climate change which are manifested as long droughts, delayed rains, heavy rains and temperature rise. The causes of the changes mentioned by the producers are: torrential rains (26,85%), bad cultivation practices (62,50%), agricultural intensification (46,76%), overgrazing (2,78%) , the abusive use of pesticides (20,37%), the increase in population (12,96%), deforestation (21,76%) and bush fires (6,48%). Globally, 98,6% of those surveyed abandoned 63 ha of land that had become irrecoverable. Producers adopt resilience measures such as providing organic manure, crop rotations and associations, the establishment of grass strips and stone bunds, bunds and reforestation to protect and restore their plots. Producers adopt adaptation measures such as adding organic manure, crop rotations and associations, construction of grass strips, stone bunds, bunds, and reforestation to protect and restore their fields. Several species of plants desired by producers for their virtue are endangered. The farmers' perception of cases of long drought are explained by the variables "age of the farmer", "the practice of animal husbandry", "access to extension services" and "the practice of agriculture". It is necessary to take these variables into account in projects and programs to fight against drought in the area. The variables "farmer's age «,» bad cultivation practices” and "deforestation" also influencing farmers' perception of soil degradation, must also be considered in programs and projects for the restoration of degraded soils in the area. It is important to study the effects of these practices on soil restoration and crop yields.

Le bonobo (Pan paniscus), est une espece endemique a la Republique Democratique du Congo (RDC). La presente etude identifie les menaces qui pesent sur ce primate au niveau de la Reserve Naturelle de Sankuru (RNSA), les priorise a partir des analyses spatiales en evaluant, de maniere comparative, l’evolution de l’occupation du sol a l’interieur et exterieur de la zone protegee. Par rapport au reste de l’aire de repartition historique du bonobo en RDC ou la chasse est une preoccupation majeure, les enquetes dans la zone d’etude revelent que l’agriculture sur brulis est la premiere menace d’origine anthropique qui influe plus sur la survie de ce primate. L’etude revele des signes d’existence d’une ignorance persistante aux lois du pays en matiere de gestion et de conservation de la nature de la part de la population locale. La croissance demographique, le manque d’alternatives de subsistance ainsi que l’expansion de l’occupation du sol a l’interieur et aux alentours de la RNSA presentent des grandes envergures spatiales et un impact tres remarquable sur le couvert vegetal. La vitesse de l’expansion du complexe rural est de 1,5% dans la RNSA soit 3600 ha/an. Cette extension se fait de facons identiques a l’interieur et a l’exterieur de la limite de la RNSA. The bonobo (Pan paniscus), is an endemic species to the Democratic Republic of Congo (DRC). This study identifies the threats to this primate in the Sankuru Natural Reserve (RNSA), prioritizes them based on spatial analyzes by evaluating, in a comparative manner, the land use evolution inside and outside the protected area. Compared to the rest of the bonobo distribution area where hunting is a major concern, surveys reveal that slash-and-burn agriculture is the first anthropogenic threat that has the greatest impact on bonobo's survival in the RNSA. The reveals signs of persistent ignorance to the country's laws on the management and conservation of nature by the local population. Population growth, the lack of subsistence alternatives as well as the expansion of the rural complex within and around the RNSA present large spatial dimensions and a very remarkable impact on the vegetation cover. The rate of expansion of the rural complex is 1.5% in the RNSA or 3600 ha / year. This extension of the rural complex is done in identical ways inside and outside the RNSA boundary.

In the granite-gneiss basement of the Zou basin, drinking water access is mainly provided by fracture aquifers. In order to facilitate the borehole drilling, this study, on one hand, established the fracture map and on the other hand evaluated the groundwater potential in this part of Benin. First, Sobel directional filters are used to extract a representation of the fracture network. From these data, three majority directions are identified: N180-N30, N90- N110 and N60-N70. Other minority groups, in particular, N130-N140, also affect these crystalline and crystallophyllian formations. The fracture lengths are concentrated in a range of 1 to 2 km (65 %) and the extreme values lower than 1 km and greater than 2 km are respectively 12.7 % and 22 %. This set of direction reveals an average fracture density of 2.4 km.km-2 with areas such as the South of Iroukou having low values (0.8 ± 0.9 km.km-2 ) and high values in Dassa (5.2 ± 0.9 km.km-2 ). These results are useful for drilling because more than 60% of boreholes located within 200 m of an identified fracture is positive. In addition, other maps such as alteration thickness, lithology, drainage, rainfall, and slope are confronted with fracture density using multicriteria decision analysis. Based on the contribution of each map to groundwater availability, the weights are 0.158, 0.074, 0.126, 0.302, 0.065 and 0.275, respectively. It turns out after spatial analysis that the basin is characterized by a very low (9.2 %) to low (18 %) potential towards Djidja, Gangan and Glazoue, moderate (24.7 %) in the Zoudji and Yagbo and good (27.5 %) to very good (20.6 %) around Savalou. The water potential of these blocks of aquifers can change significantly even at the local scale. Despite the constraints, these resources are essential to achieving the Sustainable Development Goal 6 in the basin, of course after a thorough study of the aquifers in order to guarantee drinking water supply of the populations and the durability of the boreholes.Dans le socle granito-gneissique du bassin du Zou, l'acces a l'eau potable est principalement assure par les aquiferes de fractures. Dans l'optique de faciliter l'implantation des forages, cette etude d'une part a etabli la carte de fractures et d'autre part evalue le potentiel en eau souterraine dans cette partie du Benin. D'abord les filtres directionnels Sobel sont utilises pour extraire une representation du reseau de fractures. De ces donnees, trois familles de directions majoritaires sont identifiees : N180-N30, N90-N110 et N60-N70. D'autres minoritaires notamment N130-N140 affectent aussi ces formations cristalline et cristallophyllienne. Les longueurs de fractures se concentrent dans un intervalle de 1 a 2 km (65 %) et les extremes inferieurs a 1 km et superieurs a 2 km donnent respectivement 12,7 % et 22 %. Cet ensemble de direction revele une densite de fractures moyenne de 2,4 km/km2 avec des zones telles que le Sud de Iroukou de faible valeur (0,8 km/km2 ) et Dassa de forte densite (5,2 ± 0,9 km/km2 ). Ces resultats sont utiles a l'implantation car plus de 60 % des forages situes a moins de 200 m d'une fracture identifiee est positif. De plus, d'autres cartes telles que l'epaisseur d'alteration, la lithologie, le drainage, la hauteur de pluies et la pente sont confrontees a la densite de fractures a l'aide de l'analyse multicritere de decision. Selon la contribution de chaque carte a la disponibilite des eaux souterraines, les poids sont respectivement : 0,158 ; 0,074 ; 0,126 ; 0,302 ; 0,065 et 0,275. Il ressort de l’analyse spatiale que le bassin est caracterise par un potentiel tres faible (9,2 %) a faible (18 %) vers Djidja, Gangan et Glazoue, modere (24,7 %) dans les environs de Zoudji et Yagbo et bon (27,5 %) a tres bon (20,6 %) vers Savalou. Le potentiel en eau de ces blocs d'aquiferes peut varier de facon significative meme a l'echelle locale. Malgre les contraintes, cesressourcessont essentielles a l'atteinte de l'Objectif de Developpement Durable 6 dans le bassin, bien entendu apres une etude approfondie des aquiferes afin de garantir l’approvisionnement en eau potable des populations et la perennite des forages.

The water table of the Dantiandou Valley is located between 13°10' and 13°30' north latitude and between 2°40' and 3° east longitude. Its water reserves are renewed annually as confirmed by long-term observations conducted over more than 25 years (international experiments Hapex Sahel and AMMA) having shown that the water table has experienced a continuous rise of about 4 m in 40 years despite the severe droughts in the Sahel (1970 - 1980). However, this recharge exposes the water table to evaporation and salinization. The main objective of this study is to confirm the dynamics of the water table and its often negative impacts on the salinity of water resources, thus limiting some of their uses. The methodological approach based on analysis of piezometric levels, study of physicochemical parameters and use of isotopes has yielded several important results for future freshwater availability in the region. General increase in groundwater reserves has resulted in the emergence of new permanent ponds in the lowest valley bottoms. Evaporation strongly affects the water table and increases significantly its electrical conductivity (EC up to 1000 µS.cm-1 ) while the natural mineralization of groundwater is very low (EC between 20 and 100 µS.cm-1 ). Very important enrichments of the stable isotope (O-18 and D) contents confirm the increase in salinity due to evaporation. Finally, salinization of water and soil is observed and limits the uses of water resources despite their abundance. La nappe phreatique du Kori de Dantiandou est situee entre 13°10’ et 13°30’ de latitude Nord et entre 2°40’ et 3° de longitude Est. Ses reserves en eau sont annuellement renouvelees comme le confirment les observations de terrain conduites depuis plus de 25 ans (programmes de recherche internationaux Hapex Sahel puis AMMA) qui ont montre qu’en depit des grandes secheresses au Sahel (1970 – 1980) la nappe phreatique a connu une remontee continue d’environ 4 m en 40 ans. Cependant, cette recharge expose la nappe a une evaporation et une salinisation. L’objectif principal de cette etude est de preciser la dynamique de la nappe et ses impacts souvent negatifs sur la salinite des ressources en eau, limitant ainsi certains de leurs usages. L’approche methodologique basee sur l’analyse des niveaux piezometriques, l’etude des parametres physicochimiques et l’utilisation des isotopes a permis d’obtenir plusieurs resultats importants pour la disponibilite future d’eau douce dans la region. Une hausse generalisee des reserves souterraines s’observe, se traduisant par l’apparition de nouvelles mares permanentes dans les zones les plus basses. La reprise evaporatoire directe a partir de la nappe augmente considerablement la conductivite electrique (CE superieures 1000 µS.cm-1 ), tandis que la mineralisation naturelle des eaux souterraines reste tres basse (CE entre 20 et 100 µS.cm-1 ). Des enrichissements tres importants des teneurs en isotopes stables (O-18 et D) confirment la forte mineralisation liee a l’evaporation. Enfin, il est observe une salinisation des eaux et des sols qui limite les usages des ressources disponibles, malgre leur abondance.

Located south-west of the Senegalese coast, the mouth of the Casamance River is under the influence of natural hydrodynamic factors. Thus, the beaches of the villages located around this mouth are characterized by a highly variable mobility. The purpose of this article is to analyze the variation of the position of the coastline around the mouth of the Casamance River. The methodology is based on the superimposition of a series of multidate images (aerial photographs, Landsat images and Google Earth image). Scanning jobs were done with ArcGIS 10.5 software. From there, the statistical calculations of the rates of evolution of the coastline are made with the model of DSAS4.3. The results obtained through the calculation of the mobility indices (EPR and LRR) showed a very variable dynamics of the coastline revealing two trends: a first period between 1968 and 1986, characterized generally by a progradation and a second period (1986- 2017) characterized in general by a decline in the beach, but with a slower decline between 2004 and 2017. Situee au sud-ouest du littoral senegalais, l’embouchure du fleuve Casamance est sous l’influence des facteurs hydrodynamiques naturels. Ainsi, les plages des villages situes au tour de cette embouchure sont caracterisees par une mobilite tres variable. L’objectif de cet article est d’analyser la variation de la position du trait de cote autour de l’embouchure du fleuve Casamance. La methodologie est basee sur la superposition d’une serie d’images multi-dates (photographies aeriennes, images Landsat et image Google Earth). Lestravaux de numerisation ont ete faits avec le logiciel ArcGIS 10.5. A partir de la, les calculs statistiques des vitesses d’evolution du trait de cote sont effectues avec le modele de DSAS4.3. Les resultats obtenus a travers le calcul des indices de mobilite (EPR et LRR) ont montre une dynamique tres variable du trait de cote degageant deux tendances : une premiere periode, comprise entre 1968 et 1986, caracterisee globalement par une progradation et une seconde periode (1986-2017) caracterisee globalement par un recul de la plage, mais avec un recul moins rapide entre 2004 et 2017.

Une comprehension de toutes les composantes du bilan hydrique est indispensable pour raisonner les mesures de gestion rationnelle et durable de la ressource en eau. Malheureusement, plusieurs composantes du bilan hydrique ne sont pas facilement mesurables et le recours a la modelisation est souvent necessaire. Pour ce faire, le modele SWAT 2012 (Soil and Water Assessment Tool) a ete mis en oeuvre a un pas de temps mensuel et journalier pour evaluer sa capacite a representer le fonctionnement du bassin versant Nakhla, situe a 20 kilometres au sud de la ville de Tetouan. Le traitement prealable des donnees existantes sur le bassin (MNT, pedologie, images satellitaires, donnees climatiques) a permis de reproduire les caracteristiques naturelles du terrain a une resolution spatiale adaptee aux objectifs de l’etude. La methodologie adoptee repose sur l’usage du systeme d’information geographique libre (QGIS) combine avec le modele agro-hydrologique SWAT pour effectuer des operations d’analyse et de modelisation du fonctionnement hydrologique a l’echelle du bassin versant et l’outil SWAT-Cup pour optimiser les operations d’analyse de sensibilite et d’incertitude. Le processus de calibration est realise aux echelles temporelles mensuelle et journaliere au niveau de la station Timezouk et au cours de trois periodes : de 1980 a 1983 pour l’initiation, de 1984 a 1987 pour la calibration et de 1988 a 1990 pour la validation. Les resultats obtenus apres calage et validation a l’echelle mensuelle montrent une simulation satisfaisante des debits puisque la comparaison des debits mensuels observes et simules pour la periode de calibration a abouti a un NSE de 0,83 et un R2 de 0,88 au niveau de la station Timezouk. Les resultats a l’echelle journaliere ne sont pas satisfaisant (NSE< 0.5), ce qui montre que la representation de la dynamique haute-frequence des flux d’eau doit encore etre amelioree. A comprehension of all the components of water balance is essential for rational and durable management of the water resource. However, the direct assessment of several components of the water balance is very difficult and the use of modeling is often necessary. SWAT 2012 (Soil and Water Assessment Tool) model was thus implemented on a monthly and daily time steps to assess his ability to reproduce the hydrological functioning for the Nakhla watershed, which is located at 20 kilometers in the south of the city of Tetouan. Treatment of environmental data (MNT, pedology, satellite imagery and climatic data) allowed to describing the natural characteristic of the field at a resolution adapted to the objectives of the study. Adopted methodology consisted in the combined use of the SWAT agro hydrological model implemented in the QGIS geographical information system open source for operations of analysis and modeling of hydrological processes at the level of the watershed area and of SWAT-CUP tool to optimize the operations of sensitivity and uncertainty analysis. The calibration process was performed on two temporal scales; monthly and daily; and on the stations Timezouk; and over three periods: warm-up period from 1980 to 1983, calibration period from 1984 to 1987, and the validation period from 1988 to 1990. The results acquired after calibration and validation at monthly time step were satisfactory and presented good level of realism in the simulation of the discharge. The comparison of the monthly observed and simulated discharges for the period of calibration gave a NSE of 0.83 and R2 of 0.88 at the Timezouk station. Nevertheless, daily results are not satisfactory (NSE< 0.5), thus further improvements are required to better simulate the processes at a finer time step.

Flood is a natural disaster and causes loss of life and property destruction. Its impacts are large on agriculture especially in West African countries where smallholder farmers account for 80% of all the farms. The objective of this study was to assess flood risks in the inland valley of Dosir located in the district of Pélébina, northern Benin. Rainfall, discharge and water level in the riverbed were monitored using rain gauge, acoustic current meter and pressure sensors, respectively. The hydrological functioning of the inland valley was simulated using the Integrated Flood Analysis System (IFAS) model. The calibration was done based on the land use map (GlobalMap) and the soil water holding capacity map (UNEP). Our study demonstrated the existence of a high flood hazard in the inland valley of Dosir which reacts very quickly to rainfall solicitations. The IFAS model has shown a good performance in simulating the runoff in the riverbed of the inland valley with a coefficient of determination of 0.65. The IFAS model can be used to design a flood management system in the district of Pelebina. Further studies are needed to assess the exposure and vulnerability of farmers to flood risk.

The dynamics study of the preserved forest of Mekrou was discussed. The methodology used includes documentary research, Phytosociological surveys, diachronic analysis of satellite imagery, socio-economic surveys of different social and professional groups and the analysis and interpretation of data. It is obvious that in the area of the study, agriculture, animal husbandry, forestry and the use of medicinal plants are the main forms of natural resources exploitation. This operation, with population growth leads to a regressive evolution of plants and natural landscapes in favor of agricultural fields and fallow. The area of natural vegetation increased from 70, 53% in 1992 to 39,33% in 2012 in favor fields and fallow land increased from 17, 88% to 48, 77% in 2012. The numerical classification based on the presence-absence of vegetation species allowed us to individualize 6 vegetal communities. The Anogeissus leiocarpus, Khaya senegalensis and gallery forests group is the most diversified and most concentrated while Parkia biglobosa, Vitellaria paradoxa Field group is less diversified and less dense. The impact of soil occupation dynamics has resulted in the fragmentation of natural formations and reducing species diversity and density of ligneous.

The availabilities and the commercial values of 31 agricultural and agro-industrial by-products were evaluated through a semi structural interview carried out on 360 breeders of Benin. A sample of each diet was collected to determine its chemical composition and nutritive values. Maize bran, cassava peels, cakes of soya and cotton are available in any season and have a commercial value. Among fruit by-products used in the food of the ruminants, the pineapple peels occupy the first place and their commercial values are three times higher than those of the cassava peels. Soya cakes has a very high commercial value (higher than 200 FCFA/kg).The leguminous pods and the cereal hulls are also largely available but without commercial value. Roots cassava and tubers of yam by-products and the cakes are very digestible and these values do not go down below 60 %. Low values of digestibility were observed on hulls and stems of cereals and leguminous pods. These digestibilities are generally below 40 %. The groundnut haulms are more digestible than cowpea haulms (57.8 vs 49.7 %). Cotton cakes and palm oil cakes are less digestible than the other oil cakes. The digestibilities of crude protein (DCP) are very low in fruit and cereals by-products. Except for the pods of leguminous, all the leguminous by-products provided considerable quantities in DCP. The studies give opportunities of choice of food supplementation to ruminants during the dry season where graminaceous and the other herbaceous becoming rare in the natural pasture.