QUANTIFICATION ET EVALUATION DE L’EROSION HYDRIQUE EN UTILISANT LE MODÈLE RUSLE ET DÉPOSITION INTÉGRÉS DANS UN SIG. APPLICATION DANS LE BASSIN VERSANT N'FIS DANS LE HAUT ATLAS DE MARRAKECH (MAROC)

Located in the High Atlas central-western, N'Fis basin shows a dissected topography, frequent and violent floods, and its characterization by a litho-stratigraphic succession from the Precambrian to the current that engender significant erosion, and cause reservoirs siltation. This study aims to map areas vulnerable to erosion in the N'Fis Basin, developed a Geographic Information System (GIS) into account soil types, networks of drainage and traffic direction integrating remote sensing and spatial data. The results highlight the hydrographic phenomena and their effects on water resources. To achieve the objective of calculating the RUSLE equation Factor, it was based on annual and monthly climate data, field missions, the digital elevation model and satellite imagery. The result indicates a change in the rate of erosion and the values are between 7t / ha / year downstream of the wadi N'fis and a maximum value 1221t / ha / year to non-arable areas and areas with strong slope values

Relationship Between Climate Index (WMOI, SOI) and Rainfall Variability in Azib Soltane (Sebou basin Marocco)

The objective of this study is to understand the inter-annual variability of rainfall in the region Azib Soltane in the Sebou basin and determined the relationship with climatic fluctuations (represented by Western Mediterranean Oscillation Index [WMOI] and South Oscillation Index [SOI]). To attain this objective, the time series of precipitation at Azib Soltane is being studied by continuous wavelet analysis and wavelet coherence analysis, which are particularly adapted to the study of unstable process.The wavelet analysis of rainfall shows the existence of many groups of energy, from the annual to the inter-annual scales. These bands correspond to modes 1 year, 2-4 years, 4-8 years. The wavelet analysis of coherence shows a strong coherence between WMOI / rain, SOI/rain. The discontinuities can be observed in the late 1980s, 1995. The average contribution of climate fluctuations is about of 60%. Keys words: Climate fluctuation, Morocco, WMOI, SOI, wavelets, and coherence

Some Aspects of Climate Variability and Increasing Aridity in Central Morocco over the Last Forty Years: Case of Tensift Basin (Marrakech-Morocco)

Morocco, due to its location in the Mediterranean circumference, is vulnerable to present and future climate variability and climate change. Its surface water resources are becoming ever more limited and difficult to exploit. It might be expected that the warming of the hot season and drought would result in an increase in arid and semi-arid regimes of the region. In this context, we are interested in the evolution of aridity through climate indexes, including precipitation, temperature and evapotranspiration over the last 40 years in the Tensift watershed (central Morocco). As preliminary results, in the Tensift basin, the temperature became higher during the last two decades. It diminishes paradoxally towards mountainous areas. A slight decrease of precipitation has been noticed in the foothill regions of the High Atlas and near the Haouz plain. The study of aridity evolutions by the aridity index of De Martonne and aridity index of UNEP takes into account respectively the ratio between the mean annual precipitation (P) and temperature (T) and the relationship between annual precipitation and evapotranspiration. Generally, the aridity is decreasing from downstream to upstream of the study area. But during the past two decades, the region of the Tensift knew a subtantial augmentation in arid land regime may be due to global warming and reduced precipitation measured. Typically, there is a coherence between UNEP index and the index of the De Martonne from point of view of increasing aridity, which adds robustness to the result. Keywords: Tensift watershed, De Martonne’s aridity index, UNEP index, aridity, spatial variability

Recharge characterization by geoelectrical imaging and the GIS of the Plio-Quaternary aquifer (a case study of Central Haouz- Marrakesh)

Groundwater resources in Morocco are increasingly scarce. The study area which is Central Haouz belonging to the Marrakech plain is not immune to this phenomenon. This is due to the semi-arid climate on the one hand, and on the other hand, due to accelerated population growth and the economic development implications. The Plio-Quaternary aquifer of the Central Haouz has been the subject of several studies, but its Hydrogeological characterization has been classically carried out using geological and pumping test studies. Our study is in this sense to show the importance of the contribution of GIS and Electrical Resistivity Tomography (ERT). The first GIS approach determined the Runoff coefficient, which helps to locate low runoff areas corresponding to recharge zones of the water table. These areas are chosen as the site for geophysical surveys. The second method consists to detect the effect of the recharge to increase the water table in the study area and the characterization of the aquifer. Four ERT surveys were performed showed on the aquifer the positive effect of the recharge dike recently built at the Wadi and dismantle the reliability of the GIS results concerning the infiltration zones founded

QUANTIFICATION ET EVALUATION DE L’EROSION HYDRIQUE EN UTILISANT LE MODÈLE RUSLE ET DÉPOSITION INTÉGRÉS DANS UN SIG. APPLICATION DANS LE BASSIN VERSANT N'FIS DANS LE HAUT ATLAS DE MARRAKECH (MAROC)

Located in the High Atlas central-western, N'Fis basin shows a dissected topography, frequent and violent floods, and its characterization by a litho-stratigraphic succession from the Precambrian to the current that engender significant erosion, and cause reservoirs siltation. This study aims to map areas vulnerable to erosion in the N'Fis Basin, developed a Geographic Information System (GIS) into account soil types, networks of drainage and traffic direction integrating remote sensing and spatial data. The results highlight the hydrographic phenomena and their effects on water resources. To achieve the objective of calculating the RUSLE equation Factor, it was based on annual and monthly climate data, field missions, the digital elevation model and satellite imagery. The result indicates a change in the rate of erosion and the values are between 7t / ha / year downstream of the wadi N'fis and a maximum value 1221t / ha / year to non-arable areas and areas with strong slope values

Assessment of Soil Quality for a Semi-Arid Irrigated Under Citrus Orchard : Case of the Haouz Plain, Morocco

The irrigated perimeter of the Haouz plain is one of the largest in Morocco with 310.000 Ha with intense agricultural practices based on irrigation. Besides, recent studies have shown that the aquifer is characterized by an overall average to low sensitivity and vulnerability. The objective of this study is to provide an in depth diagnosis of the current situation regarding soil quality for a drip irrigation area: a citrus orchard, in a farm named Agafay, is located in the western part of Haouz, at 35 km SW of Marrakesh. To this objective, an intensive in situ campaign has been carried out focused on the measurements of the physico-chemical parameters of soil, at nine plots. The variation of these parameters, their impact on the type of rootstock and the variation of pollutants through the five soil horizons are analyzed. The results revealed that the condition in the soil quality is not very alarming. As most of the soils are light-textured, with poor organic matter content and basic to very basic pH. The reduction of organic matter, salinity, orthophosphates and nitrates with depth is attributed to the localized mode of irrigation adopted at the site which minimizes the loss of nutrients and, in fine, pollution of the aquifer. Multivariate analysis shows that the total and lime correlate well with the pH, which in turn correlate negatively with nitrate content and soil electrical conductivity. This work has strong implications for the quality assessment of soil for all irrigated perimeters by the drip in semi-arid areas, order to ensure the conservation and sustainability of the production system

Preliminary Hydrogeological Investigations for Sustainable Development in the Courel Mountains UNESCO Global Geopark (NW Spain)

Congreso realizado en Málaga en junio de 2022.[EN] Karst aquifers and, especially, their caves and springs, are singular sites of the geoheritage due to their scientific, touristic and use (water resources) values. Besides, they are recognized as habitats of special protection by the Habitat Directive (92/43/CEE) and would be used for sustainable development in UNESCO Global Geoparks (UGGp). However, their management continues to be a challenge at the present day since karst aquifers and their associated springs and caves are vulnerable environments used by many actors and affected by land uses and changes in surface hydrology and groundwater. Our work aims to implement of a suitable management of aquifers and springs in the Courel Mountains UGGp based on hydrogeological studies. The studies include mainly the characterization of aquifers’ functioning, the elaboration of the spring inventory, physicochemical analyses and geoconservation actions.This work is funded by the Courel Mountains UGGp and the project IGCP-730 Hydrogeological significance of Mediterranean geoparks, and supported by the International Geosciences Program of UNESCO.Peer reviewe

Groundwater Depletion in an Urban Environment under Semiarid Climate and Persistent Drought–City of Marrakesh (Morocco)

The quantitative monitoring of the shallow aquifer in Marrakesh and its surrounding area shows that the water table has been lowered gradually over the last 40 years, and attaining an acute decline in the early 2000s. This declining trend—if confirmed in the future—may lead to a water shortage, or even to a total aquifer depletion, which would be devastating for a region where economic activity and drinking water supply rely partly on groundwater resources. Two factors account for this situation: the hot semi-arid climate characterized by high temperatures and low precipitation, causing an inadequate groundwater recharge (deficit between rainwater supply and the potential evapotranspiration), and the over-pumping of groundwater from wells for intensive agricultural uses and some leisure activities (golf courses, waterparks and pools, for example). The objective of this study is to assess the hydrodynamic behaviour of the shallow aquifer in this context of persistent drought and semi-arid climate under intense use conditions. Based on earlier research studies and hydrological data recently collected from the field, a spatiotemporal analysis using a geographic information system has been conducted, allowing researchers to monitor the evolution of groundwater resources under the impact of intense exploitation. This study shows a general decline of groundwater level in the city of Marrakesh between 1962–2019. However, by dividing this period into three periods (1962–1985, 1986–2001 and 2002–2019), it is obvious that the main groundwater fall occurred during the two last decades, a period marked by highest recorded temperatures and decreased precipitation levels. This water table decline impacted 85% of the study area and is estimated at 0.9 m/year. The area most affected by the drawdown of the water table experienced a decline reaching 37 m between 2002 and 2019 (more than 2 m a year)