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Some Aspects of Climate Variability and Increasing Aridity in Central Morocco over the Last Forty Years: Case of Tensift Basin (Marrakech-Morocco)
Abstract and Figures
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.
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... Morocco is among the regions affected by both these constrains [1,2]. Indeed, Morocco is vulnerable to climate change, its arid and semi-arid regions would be more susceptible to drought and warm in the hot season [3]. The climate change affects the availability of water [3] which causes a high salinity of soils and reduces the productivity of many crops. ...
... Indeed, Morocco is vulnerable to climate change, its arid and semi-arid regions would be more susceptible to drought and warm in the hot season [3]. The climate change affects the availability of water [3] which causes a high salinity of soils and reduces the productivity of many crops. It's well known that legumes are among the most important crops for human nutrition because they provide a high level of proteins compared to other plants [4]. ...
... It's well known that legumes are among the most important crops for human nutrition because they provide a high level of proteins compared to other plants [4]. In addition, the legumes play an important role in sustainable agriculture by offering many economic and environmental advantages, in particular their ability to fix nitrogen in symbiosis with rhizobia, for this reason they are mainly used to improve the fertility of saline soils [3,4,5,6,7]. However, legumes are sensitive to both drought and salinity, which limit their growth and production in many areas with particular severe drought and salinity conditions [3,5,6]. ...
... Moreover, the continental climate significantly increases drought vulnerability in the MS region, particularly in the Haouz plain, where reduced precipitation, elevated temperatures, and evaporation contribute to the risk (Fniguire et al. 2014;Bennani et al. 2016). Climate change and variability have led to rainfall deficits, posing a substantial drought risk in central Morocco. ...
In the semi-arid Marrakech-Safi (MS) region of southwest Morocco, climate change has amplified drought occurrences, posing significant threats to water resources and agriculture. A comprehensive understanding of drought patterns is imperative to manage these risks and enhance resilience effectively. Precipitation from 18 pluviometer stations was employed to analyze meteorological drought using the standardized precipitation index (SPI) from 1980 to 2018. Additionally, agricultural drought is quantified using three remote sensing-driven indices: vegetation condition index (VCI), temperature conditions index (TCI), and vegetation health index (VHI) from 2000 to 2018. These indices are correlated with SPI to evaluate their performance and gauge vegetation sensitivity to meteorological drought. The Mann–Kendall test assesses trends in drought events and their severity. The results demonstrated that SPI, VCI, TCI, and VHI experienced alternating dry and wet periods with an overall upward trend, especially in mountainous areas, plateau zones, and Haouz plain of the MS region. The correlation analysis establishes a significant relationship between remote sensing-based indices and SPI-6, with mean correlation coefficients exceeding 0.6. The findings underscore the importance of considering multiple time scales to comprehensively assess climate's impact on vegetation. Seasonal drought trends analysis indicates no significant negative trends in winter and spring but positive trends in autumn.
... (Wang et al., 2016), which includes monthly data as well as annual mean (MAT), maximum (T MAX ) and minimum (T MIN ) temperature and total annual precipitation (TAP) for the 1964-2016 period. We used the monthly temperature data to calculate the mean temperature of the growing season (T GS ; months of April through September), spring mean temperature (Tspring; months of April through June), and winter mean temperature (Twinter; months of January through March), The annual aridity index (AR I ) was calculated with the equation AR I = TAP/(MAT+10) (Fniguire et al., 2014). To verify that the data from the ClimateNA software accurately reflected the conditions at the study locations, we calculated the correlation between the ClimateNA data, and the data recorded by local meteorological stations. ...
Introduction
Phenotypic plasticity (PP) could be an important short-term mechanism to modify physiological and morphological traits in response to climate change and global warming, particularly for high-mountain tree species. The objective was to evaluate PP response of growth ring traits to temperature and precipitation in Pinus hartwegii Lindl. populations located at the ends of its elevational gradient on two volcanic mountains in central Mexico (La Malinche and Nevado de Toluca).
Methods
Increment cores collected from 274 P . hartwegii trees were used to estimate their PP through reaction norms (RN), which relate the ring width and density traits with climate variables (temperature and precipitation). We estimated the trees’ sensitivity (significant RN) to climatic variables, as well as the relative proportion of RN with positive and negative slope. We also estimated the relationship between the PP of ring width and density traits using correlation and Principal Component (PC) analyses.
Results
Over 70% of all trees showed significant RN to growing season and winter temperatures for at least one growth ring trait, with a similar proportion of significant RN at both ends of the gradient on both mountains. Ring width traits had mostly negative RN, while ring density traits tended to have positive RN. Frequency of negative RN decreased from lower to higher elevation for most traits. Average PP was higher at the lower end of the gradient, especially on LM, both for ring width and ring density traits, although high intrapopulation variation in PP was found on both mountains.
Discussion
Results indicate that P. hartwegii presents spatially differentiated plastic responses in width and density components of radial growth. PP was particularly strong at the lower elevation, which has higher temperature and water stress conditions, putting these populations at risk from the continuing global warming driven by climate change.
... The Standardized Precipitation Index (SPI) is used to analyze the evolution of drought severity degrees in the Marrakech Safi region during the period 1982-2015. The results show a succession of dry and wet years, but over the past two decades, the Marrakech-Tensift region has experienced a substantial increase in the dry land regime due to global warming and the reduction in measured precipitation (according to the Marton aridity index) (Fniguire and Laftouhi, 2014). ...
... It is characterized by aridity over a large part of its surface with a concentration of precipitation mainly from November to April. (Fniguire et al. 2014). Located around latitude 31° North and longitude 8° West, it occupies an important mountain range in the south which culminates at 4167 masl (the highest peak in North Africa). ...
In this study, we apply statistical approaches based on frequency analysis and Artificial Neural Networks to map the 100-year monthly precipitation in a Moroccan watershed. This was accomplished by using assessed and corrected satellite-based rainfall products. A network of 10 rain gauges and six statistical validation criteria was used to compare in situ measurements and monthly rainfall estimates from the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) product for the rainy season (from November to April). Results indicate a fairly good agreement between the two data sources, with high correlation coefficients (> 0.5) for all months and low bias values (< 17%) especially for November, January, February and April. To correct the bias, we used an ANN model, with station coordinates and the monthly CHIRPS precipitation as input. The precipitation estimated by the ANN model was then compared with ground-based measurements. This simulation of monthly precipitation seems better, with significant Nash criteria and Pearson correlation coefficients (0.83-0.9). We then used this model to correct the CHIRPS gross precipitation and to perform a frequency analysis using spatial patterns of corrected rainfall. The results show that mountainous areas are conducive to high monthly precipitation amounts. These areas contrast with a potentially arid plain. This observation requires water supply plans which would consist of water transfers from surplus areas to deficit ones.
... (Kahime et al., 2018) found out that irrigation accounts for more than 85 % of water uses in the study area. The average annual water demand will dramatically increase in the region in the coming decades (Fniguire et al., 2014;Tanouti, 2017). This paper has shown that the study area is rich in water supply, therefore dams for irrigation, and potable water could be created to contribute to the increasing demand of water in the region. ...
Land use change at the local stage affects the flow of ecosystem services at all levels. Analyzing the causes of land use change such as anthropogenic activities in the case of the Ourika watershed will facilitate sustainable policies. A decision-making tool, InVEST (Integrated Valuation of Ecosystem Services and Trade Offs) was used to quantify three ecosystem services and to generate three spatially explicit land use scenarios (trend, development and conservation) with expert stakeholders and the local population. The results indicate that forest expansion under the conservation scenario increased carbon sequestration and sediment retention by 34.29 % and 7.17 % but decreased water yield by 0.75 %. Comparably, a combination of forest and cropland expansion under the trend scenario generated a moderate increase by 8.4 % and 0.98 % but a negligible decrease of 0.09 %. A decline in the forests under the development scenario caused an improvement in the water yield by 0.12 % but a decrease in carbon sequestration and sediment retention by 6.06 % and 0.88 % respectively. A combination of forests and croplands through agroforestry systems enhances the provision of all the three ecosystem services. Community-based ecosystem and land management is the best way to improve ecosystem services at the local level.
... The UNEP aridity index (AI; abbreviations in Table 1) is based on the ratio be tween precipitation (P) and potential evapotranspiration (PET) (UNESCO 1979). Alteration of the AI index due to the impacts of climate change has been reported worldwide (Sailer 2013, Girvetz & Zganjar 2014 and for different catchments (Arora 2002, Paulo et al. 2012, Ficklin et al. 2013, Fniguire et al. 2014, Li & Chen 2015. In particular, aridity trends have a regional basis, e.g. an increase in aridity was demonstrated in most of southern Europe (Paltineanu et al. 2007, Colantoni et al. 2015, while no annual trends were observed in Serbia (Hrnjak et al. 2014). ...
Changes in the reference evapotranspiration (ET0) and precipitation (P) patterns in the Nemunas River basin (Baltic Sea catchment) are evident today and will be even more significant in the future. Nemunas basin aridity dynamics (1901−2010) and projections (2081−2100) were evaluated using the UNEP aridity index (AI). Historical analysis (CRU TS3.24.01) and future projections (EURO-CORDEX) of monthly air temperature and precipitation were used for the AI estimation. Projections of the meteorological parameters according to 4 Representative Concentration Pathway scenarios (RCP2.6, 4.5, 6.0 and 8.5) were used in the analysis. In the Nemunas River basin, evapotranspiration exceeded precipitation from April to August, and in a large part of the basin the climatic conditions during this part of the year could be described as dry subhumid (AI < 0.65). Since the 1980s, increased aridity has been observed between April and August due to a strong positive trend of ET0 and a strong negative trend of P. Future projections (2081−2100) show that despite large uncertainties in the climate projections, it is more likely that the Nemunas basin climate will become more humid in April and May and drier between June and August. The increase in climate aridity during these months is more likely in the southern and central parts of the basin.
... The spatial variability of the SPI and the drought degree accentuation from the ancient to recent dry cycle are influenced by the climate change affecting this area. A recent study demonstrated a drought accentuation in the mountainous areas of the Tensift basin, as well as all the Moroccan mountains (Fniguire et al. 2014). ...
In the last few decades, drought has become a chronic phenomenon in Morocco. It began at the end of the 1970s and continued to the late 2000s. In the present study, hydrometeorological data sets, Standardized Precipitation Index method, and non-parametric tests were used to recognize the frequency and the severity of drought events during the period between 1929 and 2010. The Standardized Precipitation Index showed significant inter-annual fluctuation and evolution of rainfall amounts representing wet cycles (i.e., before 1975) followed by a long period of drought between 1975 and 2004. The inter-annual variability of rainfall is accompanied by shifts of stationarity in the rainfall series. The statistical test of Pettitt, Bayesian method of Lee and Heghinian, Buishand procedure, and Hubert test revealed shifts around the mid 70s. After this period, a deficit of rainfall (with a maximum value of −30 %) was registered. The probabilities of monthly Standardized Precipitation Index values were normal to below normal during the last 40 years. In fact, the increase of drought risk may be resulted from the increase of frequency and severity of meteorological drought. The proposed Standardized Precipitation Index method and non-parametric tests yielded reasonable and satisfactory results for Morocco. Therefore, this approach could be successfully applied to other semi-arid, dry, sub-humid, or semi-humid regions worldwide, where rainfall series are showing high seasonality and year-to-year variability.
... The spatial variability of the SPI and the drought degree accentuation from the ancient to recent dry cycle are influenced by the climate change affecting this area. A recent study demonstrated a drought accentuation in the mountainous areas of the Tensift basin, as well as all the Moroccan mountains (Fniguire et al. 2014). ...
In the last few decades, drought has become a chronic phenomenon in Morocco. It began at the end of the 1970s and continued to the late 2000s. In the present study, hydrometeorological data sets, Standardized Precipitation Index method, and non-parametric tests were used to recognize the frequency and the severity of drought events during the period between 1929 and 2010. The Standardized Precipitation Index showed significant inter-annual fluctuation and evolution of rainfall amounts representing wet cycles (i.e., before 1975) followed by a long period of drought between 1975 and 2004. The inter-annual variability of rainfall is accompanied by shifts of stationarity in the rainfall series. The statistical test of Pettitt, Bayesian method of Lee and Heghinian, Buishand procedure, and Hubert test revealed shifts around the mid 70s. After this period, a deficit of rainfall (with a maximum value of −30 %) was registered. The probabilities of monthly Standardized Precipitation Index values were normal to below normal during the last 40 years. In fact, the increase of drought risk may be resulted from the increase of frequency and severity of meteorological drought. The proposed Standardized Precipitation Index method and non-parametric tests yielded reasonable and satisfactory results for Morocco. Therefore, this approach could be successfully applied to other semi-arid, dry, sub-humid, or semi-humid regions worldwide, where rainfall series are showing high seasonality and year-to-year variability.
The Haouz aquifer is undergoing climatic aridity and anthropic pressure largely related to the agricultural sector. In this study, special attention was given to the main factors that have a direct impact on the fluctuations of the piezometric level (PL). Different statistical analyses (cross-correlations, PCA, cascading analysis) of the relationship between these factors were applied here. The results identify three distinct groundwater operating systems. The first is manifested in areas dominated by groundwater irrigation. The correlation is insignificant between the PL and surface water (R ≤ ±0.3). The natural balance of the water cycle is then disturbed causing a pronounced deficit in the PL. The second system is perceptible in areas dominated by irrigation from surface water, while the third system is noticeable in Bour areas, cultivated in rainfed mode. For both systems, the hydrological cycle is preserved, and the contribution of surface water to groundwater recharge is noticeable (±0.4 ≤ R ≤ ±1). Drought transfer between the water cycle components occurs in a cascading process for both systems. These results can help decision-makers to identify the risks related to groundwater vulnerability to climatic variability and overexploitation in the Haouz region, allowing for the promotion of efficient groundwater management.
This research work has led to the elaboration of a methodology capable of characterising, evaluating and protecting water resources in regional aquifers, by combination Geographical Information Systems (GIS), geophysics and geostatistics. These tools are linked mutually by exchanging Input and Output data. Additionally, a new methodology is also proposed for characterising aquifer vulnerability and sensitivity to pollution. This aquifer vulnerability is based on different aquifer parameters such as recharge, soil type, unsaturated zone; while the sensitivity is only based on the saturated zone characteristics (water velocity, global water quality and productivity).
These methodologies have been applied to the Haouz aquifer, which extends to an area of 6000 km2 for which an important database is available with respect to large prospecting works, monitoring and water resources management. This database is generally organised as files, tables and manual maps for which the information are difficult to update or to use immediately. This aquifer system is the subject of an overexploitation for different water use and a negative impact of conjunctive successive droughts in the region, which is translated to the present deficit estimated to 200 million m3. In addition, several potential pollution sources contribute in decreasing groundwater quality of this system that plays an important role in the socio-economic development of the Haouz region. This application results in the following:
1. Development and management of a Geographical Information System using MapInfo (4.0) and ArcView (3.1). This GIS is based on the available geological and hydrogeological data and is very helpful for the decision-makers in water resources. In fact, this has shown the aquifer sectors of best groundwater potential such as the central part and with low to medium global vulnerability and sensitivity to pollution. However, this GIS shows that the Issil well field is located in a sector with high vulnerability and medium sensitivity; while the N’Fis field is located near a sector with medium vulnerability and high sensitivity. Hence, these important well fields must be immediately protected by wellhead protection.
2. A significant statistical correlation is obtained between transmissivities and transversal aquifer resistances (TR) ( 50 Ohm.m), and has led to deduce transmissivity and permeability maps from the correlated values of TR. This regression has the benefit to guide the future installed pumping wells and can approach already the well productivity just from the field electrical prospecting.
3. Estimation of different aquifer parameters (based on a grid of 2 km x 2 km) such as the geometric parameter fields (impervious basement elevation and saturated depth), hydrodynamic and geoelectric parameters (transmissivity, permeability, storage coefficient and TR); by using the linear geo-statistical methods (kriging and cokriging) after fitting the experimental variograms to the theoretical ones of each parameter.
Keywords: Morocco, Haouz of Marrakech, support decision, water resources management, GIS, vulnerability, sensitivity, statistical fitting, statistical correlations, geophysics, transversal resistances, geostatistics, variogram, kriging, cokriging.
"Lille-thèses, ISSN, 0294-1767"--Fiche header. Thesis (doctoral)--Université de Paris-Sorbonne, Paris IV, 1994. Microfiche.
Le bassin versant de l’Ourika, situé dans le Haut-Atlas de Marrakech, présente une forme allongée avec des pentes très importantes au niveau des affluents et des versants. Du point de vue lithologique, il est formé de roches cristallines du socle à la partie amont, et de dépôts silteux et argileux permo-triasiques plus tendres à l’aval. Ces terrains assez imperméables augmentent les risques d’inondation. Cette situation favorise une augmentation des volumes d’eau mobilisés par le cours d'eau principal et le développement d’importantes crues. La charge solide charriée ou en suspension provient généralement des deux types de terrains soumis localement à une érosion intense. Les produits d’érosion qui sont stockés en amont, sous formes d’éboulis ou de cônes de déjection, aux ruptures de pentes des bas versants ou des confluences, sont remobilisés en périodes de crue quand les débits augmentent. Le 17 août 1995, un orage abattu en amont du bassin versant, a provoqué une crue violente et de courte durée. Cette crue dévastatrice fût consécutive à une pluie intense, couplée à un environnement géomorphologique propice au ruissellement.
L'objectif de ce travail de thèse est de comprendre et de modéliser le fonctionnement hydrologique
d'un bassin versant en s'attachant au réalisme des processus intermédiaires simulés.
Le contexte spécifique de l'étude est tout d'abord présenté ainsi que le modèle utilisé dans le travail (le
« Soil and Water Assessment Tool ») et le terrain sur lequel il est appliqué : un bassin versant
montagneux semi-aride de 227 km² qui est un sous bassin amont du Tensift (sud du Maroc). Les
performances de modélisation du modèle SWAT sont illustrées et discutées. Une restitution
satisfaisante de l'hydrogramme est possible dès lors que l'on dispose d'un jeu de précipitation
représentatif de l'ensemble du bassin. Cependant, une restitution correcte du débit ne garantie pas une
simulation réaliste des processus intermédiaires du cycle hydrologique.
Aussi, le réservoir neigeux est analysé en détail. L'instrumentation spécifique mise en place et
l'implémentation d'un schéma de neige à base physique ont permis d'approfondir l'étude de la
dynamique verticale du manteau neigeux. Les mesures satellites ont fournis des données de validation
de la simulation de la dynamique latérale du couvert neigeux. Pour compléter l'étude de processus à
dynamique relativement lente, les écoulements profonds ont été caractérisés via une étude
géochimique.
Parallèlement à ces travaux, une instrumentation météorologique a été mise en place : elle est
nécessaire à la caractérisation de processus plus rapides contribuant au débit. L'apport de mesures in
situ aux simulations est analysé.
Enfin, en guise de synthèse, une « application » est proposée dans laquelle l'ensemble des résultats est
exploité et où l'impact d'une diminution du réservoir neige est analysé.
Ce travail a permis d'aboutir à une modélisation réaliste des principales composantes de l'écoulement
dans cette zone, il a aussi mis en évidence les performances de l'outil retenu pour différents processus. (Résumé d'auteur)
Aridity is a term that most people conceptually understand, and it evokes images of dry, desert lands with sparse natural surface-water bodies and rainfall, and commonly only scant vegetation, which is adapted to a paucity of water.
In the first part of this article a review of various approaches to the problem of defining aridity is given and particular emphasis is placed on a critical analysis of different indexes used for this purpose, such as those developed by Köppen, de Martonne, Emberger, Gaussen, etc. For comparison, the modern water-balance concept, as developed by e. g. Thornthwaite, Penman and Budyko, is also discussed. In the latter part of the article, as an example of a practical study of aridity conditions, a summary is given of an investigation of agroclimatology in the Near East made by the author in co-operation with G. Perrin de Brichambaut. Comparisons are finally made between the outcome of calculations of various indexes for certain stations in the Near East for which the water-balance conditions were established during the above investigations.