Introduction

Climate change and increasing drying trends in the Mediterranean region are intensifying water scarcity, threatening both drinking water availability and agricultural production, and thus jeopardizing regional food security and social stability1,2,3,4. Identified as a climate hotspot, the Mediterranean basin is facing an increase in water demand, further underlining the ever-growing relevance of water-related issues5,6,7. This is especially critical for North African countries, where it is exacerbated by the region’s arid climate, rapid population growth, and inefficient water management practices8,9,10,11. This shortage has an impact not only on irrigation water supplies but, most notably, on drinking water requirements, especially in southern Mediterranean countries12,13,14,15.

Additionally, the increased frequency and severity of extreme climatic events, particularly droughts, has further accentuated the discrepancy between water availability and demand over both space and time scales4,16,17. This growing imbalance presents significant challenges in ensuring reliable access to water and food18,19. While climate variability is a clear factor influencing water storage, human activities, particularly irrigation, are becoming increasingly decisive12,15,20. For instance, Morocco’s agricultural sector accounts for 88% of the country’s water consumption, whereas the primary sources of water are streams, large reservoirs, seasonal snowmelt, and groundwater aquifers11,21,22,23,24,25.

Throughout seasonal peak irrigation periods, water flows from major basins are often insufficient11,26,27. To overcome this issue, Moroccan policymakers have implemented a dam-building strategy aimed at improving regulation and optimizing water management, ultimately enhancing water supplies in Morocco and thereby improving agricultural yields28. However, large-scale anthropogenic interventions have consequences. Activities such as land-use changes, dam and reservoir construction, and large-scale surface and groundwater withdrawals have been shown to have adverse effects on downstream river basins29,30,31. These activities also exacerbated imbalances between mountainous and lowland regions. While dam construction offers advantages in Morocco, it also presents significant challenges32,33. For instance, the construction of dams has led to communities relocating their settlements and ecosystems deteriorating34 as a result of reduced groundwater recharge.

Although the water stored in these dams and reservoirs is mainly devoted to drinking water, the agricultural sector gets the lion’s share. Indeed, it contributes almost 15% to Morocco’s GDP and employs around 45% of the economic manpower, most of whom are represented in rural communities. Climate change continues to cause more frequent and intense droughts worldwide7,35. Especially in the Mediterranean region, including Morocco, the climate projections suggest more frequent hot days, an increase in air temperature, and a decrease in precipitation amount36,37,38,39. Morocco is already considered under water stress with only 500 cubic meters of freshwater per capita per year, compared to 2500 cubic meters in 196040,41,42,43. Thus, Morocco is expected to reach an extremely high level of water stress by 204044. Therefore, it becomes even more critical for Morocco to manage its water resources effectively to ensure food security and sustain its agricultural sector45.

Monitoring the evolution of reservoirs is challenging due to the large surface area that needs to be covered46. This makes it an expensive task due to the cost of purchasing, installing, and monitoring all the necessary sensors required to cover a large surface47,48. In-situ measurements are essential for understanding the dynamics of water bodies; however, the cost and difficulty of accessing reliable information on water bodies make it challenging for both the scientific and stakeholder communities49,50.

Understanding the status of reservoirs, both in terms of surface area and volume, is vital for comprehensive analyses of water resources, as well as the broader hydrological and ecological implications51,52,53. While the significance of dams is widely acknowledged, comprehensive data on their evolution is often limited due to varied financial constraints54,55,56. To our knowledge, a detailed assessment of dam evolution, specifically focusing on large reservoirs in Morocco, remains to be undertaken. To address these issues, earth observation has become an increasingly effective method for monitoring water bodies57,58. This technique has been widely used to examine various continental water bodies, including lakes and reservoirs59. It has provided valuable insights into the water extension60 and water quality61. Moreover, satellite radar has become a more reliable and accurate instrument for determining the elevation of open water bodies62.

Given this background, the primary objectives of the present study are to utilize remotely sensed radar data to evaluate the spatial extent and status of dam water levels. In pursuit of this overarching goal, we have defined two specific objectives: i) mapping the water extent using satellite imagery; ii) considering all Moroccan dams operating at volumes equal to or above 100 Mm3, then focusing on the country’s second-largest dam, the Al Massira dam which is located in the Oum Er-Rabia basin; and iii) further discussing the underlying reasons for the observed changes in water extent.

Material and method

Study area

As a North African country, Morocco is situated in the southwestern Mediterranean region, Where It stands out with its diverse geography and climate63,64. It is well known for its dam strategy, which is crucial in water resource management and supports the country’s socio-economic development27,65. These dams serve multiple purposes, including domestic water supply, agricultural irrigation, industrial needs, and hydropower generation33,66. The construction of big reservoirs in Morocco has significantly contributed to storing and managing water resources, especially in arid and semi-arid regions67. These reservoirs act as strategic water reserves, helping to mitigate the impacts of water scarcity and droughts, which are common in the country. They provide a reliable and consistent water supply, supporting agricultural productivity and reducing dependence on rainfall for irrigation.

The present study examines all of Morocco’s dams with volumes equal to or above 100 Mm3. It focuses on the country’s second-largest dam, the Al Massira Dam, in the Oum Er-Rabia basin (Fig. 1).

Fig. 1
figure 1

Map of northern Morocco’s major reservoirs and their storage capacities, categorized by volume, size, and color intensity, representing the relative capacities of the reservoirs ( generated using QGIS).

Full size image

Methodology

Sentinel-1 imagery was selected because it can penetrate cloud cover and provide reliable data under all weather conditions. This makes it ideal for continuous monitoring in regions with frequent cloud cover (35% to 50% of Sentinel-2 images covering Morocco have a cloud presence, depending on the region). The Sentinel-1 imagery was pre-processed through steps to ensure data quality and consistency. First, thermal noise was removed from the images to eliminate any artificial signals that could interfere with the analysis. Following this, radiometric calibration was performed, converting the backscatter values to sigma nought (σ⁰) to maintain consistency in reflectivity measurements68. A Lee filter was applied to address the inherent speckle noise in SAR data69, which enhanced the interpretability of the imagery. The next step involved geometric correction, where the images were terrain-corrected using a Digital Elevation Model (Copernicus DEM) to account for distortions caused by topography, thereby ensuring accurate geo-referencing70. Finally, the data were resampled to a standard grid, typically at a 20-m resolution, to enable consistent analysis across the dataset.

Three methods were compared to extract water bodies from the pre-processed Sentinel-1 images. First, thresholding was employed, where a fixed threshold was applied to the backscatter values (σ⁰) to distinguish between water and non-water pixels. The threshold value was determined through an iterative optimization process using histogram analysis of Sentinel-1 backscatter values for water and non-water pixels. Multiple threshold values were tested (0.01 increment), and -18.34 was identified as the optimal cutoff based on the best separation between water and non-water classes. This selection was further validated by comparing extracted water bodies with manually digitized reservoir boundaries from high-resolution Pleiades images, ensuring consistency and accuracy in water delineation. Second, a Support Vector Machine (SVM) and a Random Forest classifier were trained using labeled training data representing water and non-water classes. This classifier was then applied to the imagery to generate a map of water extent . The performance of this classifier was compared with that of the other two methods (Fig. 2).

Fig. 2
figure 2

Overview of the Perspective Analysis Workflow.

Full size image

To validate the accuracy of the extracted water bodies, we manually digitized reservoir boundaries from high-resolution Pleiades images (2.8 m of spatial resolution at multispectral bands) acquired over nine regions. These manually delineated boundaries served as reference data for independent validation. The evaluation included a comparison between the extracted water extent from Sentinel-1 and the digitized Pleiades reference data, ensuring a robust assessment of accuracy . The accuracy of each method was measured using the Kappa coefficient, overall accuracy, and confusion matrices. Random Forest consistently outperformed the other techniques in these evaluations, leading to its selection for subsequent analysis. Indeed, the Random Forest classifier was ultimately selected as the primary method due to its superior performance, which was measured by the Kappa statistic (≥ 0.95). In comparison, the Support Vector Machine (SVM) classifier and the thresholding method achieved Kappa values of 0.92 and 0.91, respectively.

Similar studies have demonstrated the effectiveness of using SAR data combined with machine learning for surface water mapping. For example59, successfully applied Random Forest and other classifiers to Sentinel-1 imagery for delineating water bodies in different regions of the world, highlighting the robustness of these methods in remote sensing applications. Sentinel-1 images were chosen for this study due to their high temporal resolution and sensitivity to water extent, which are critical for capturing dynamic changes in water extent over time71. This consistent temporal and spatial coverage enhance the reliability of trend analyses, such as those performed using Sen’s slope72, to robustly quantify the rate of change in water extent.

Moreover, to analyze the trends in water extent, we also computed trends in meteorological data from the ERA5-Land reanalysis dataset73. The generated water extent maps were compared with this hydro-meteorological data, specifically focusing on climatic factors such as precipitation and temperature. This comparative analysis provided valuable insights into how changes in these climatic variables influence water body dynamics. By examining the trends in both water extent and meteorological data, we gain a better understanding of the effects of climate conditions and the observed fluctuations in water bodies (Fig. 2).

Results and discussion

Water extension in the main reservoirs

The temporal dynamics of the surface area of selected reservoirs in Morocco, spanning from July 2018 to January 2024, reveal significant variations (Fig. 3). Al Wahda reservoir, situated in the north, shows a relatively stable yet slightly declining trend, maintaining comparatively higher water levels throughout the observation period. Conversely, reservoirs located in central and southern Morocco, such as Al Massira and Mansour Eddahbi, exhibit a more pronounced decline in water surface area, particularly noticeable from mid-2021 to early 2024 (Fig. 3).

Fig. 3
figure 3

Temporal evolution of the water extent (Km2) for the main reservoirs from April 2018 to June 2024.

Full size image

However, in the following years, there was a noticeable and steady decline in surface area, resulting in a severe reduction in water extent . The sharp decrease between 2021 and 2023 is particularly striking, likely reflecting the impact of successive droughts.

The analysis is further refined by Sen’s slope, which represents the percentage change in the water extent over time relative to the initial surface (Fig. 4). The graphic clearly illustrates the contrast between trends in most reservoirs. Whereas dams with a positive Sen slope, such as Hassan II and Sidi Chahed, show an increase in water extent over time, which suggests that conditions in these areas continue to benefit from stable or even improving hydrological resources, dams with a positive Sen slope, such as Hassan II and Sidi Chahed, show an increase in water extent over time, which suggests that these areas continue to benefit from stable or improving hydrological resources37. These dams are mainly located in northern Morocco. On the other hand, dams with significantly negative Sen slopes, such as Al Massira and Bin El Ouidane, reveal a substantial decrease in water extent, highlighting that these regions have experienced and continue to have a substantially reduced water supply.

Fig. 4
figure 4

The percentage change of Morocco’s dams’ area based on Sen’s slope indicator.

Full size image

Explaining the changes: climatic variability

Analyzing precipitation patterns in northern Morocco from 1980 to 2023, as shown in Fig. 5A, reveals significant trends with important implications for water resource management and drought mitigation in the region. Total annual precipitation is presented over the years in Fig. 5A, highlighting in red years where precipitation amounts dropped below the 25th percentile (first quartile). The overall trend, indicated by the black line, shows a steady decline in annual precipitation with a slope of -7.77 mm per decade. Reduced precipitation implies a progressive long-term decrease in water availability11,36, thus exacerbating the region’s vulnerability to droughts and severe water shortages.

Fig. 5
figure 5

Long-Term Trends and Spatial Variability of Annual Precipitation in Moroccan Basins (1980–2023).

Full size image

The first evident consequence of the decreasing precipitation trend is the reduction in reservoir surface area across Morocco from April 2018 to June 2024, as illustrated in Fig. 5A. The problem extends beyond water volumes; the timing of water availability is becoming a critical concern. The rainy season plays a decisive role in replenishing reservoirs, and yet it is becoming increasingly unpredictable. At the same time, increasing temperatures are leading to excessive snowmelt in the Atlas Mountains, a vital source of water for the reservoirs, disrupting the steady year-round stream flow needed to meet the region’s growing agricultural requirements and replenish dams6,37,38. Indeed, the straightforward correlation between reduced precipitation and reservoir area retraction highlights the tight correlation between climate change and the hydrological water balance, stressing the impacts of lower precipitation on water availability in the region.

Moreover, numerous studies have already established that global warming is exacerbating the water cycle, thus affecting the worldwide precipitation distribution74. Even the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) emphasizes that average precipitation in semi-arid and arid regions tends to decrease by around 0.3% per decade (in Morocco’s case, this rate has been around 2.59%)75. Partly due to its geographical location in a hotspot of the Mediterranean Basin, Morocco has been significantly affected by global warming. This has been supported over time by data from the ERA5 reanalysis, which has shown that most parts of Morocco have experienced a substantial decline in precipitation and a noticeable increase in temperature. In many regions, these trends are leading to growing pressure on water resources, as shown in Fig. 5A .

In addition, the Z-score was used to identify dry periods for the precipitation time series between 1981 and 2023. The results reveal an alternation between dry and wet periods, starting with a drought from 1981 to 1986. From 1987 to 1989, the Z-score was relatively weak, ranging between 0.75 and 2.5. Then, a second dry period from 1990 to 1995, followed by a very short but wet 1996, with the dry period continuing until 2001. From 2002 to 2007, the conditions were slightly mixed, with a dry trend in some southern basins and a somewhat wet pattern in northern basins. While 2008 started with neutral values for the central Moroccan basins and wet conditions for the south and north basins, this was followed by the wettest year in Morocco’s recorded climatic history in 2009, especially for the northern basins, with a Z-score exceeding 3; this period lasted until 2014. Following the wettest year, the country experienced one of the most prolonged dry periods from 2015 onwards, except for 2018, which was relatively damp and has continued to intensify with increasing severity across the country (Fig. 5B).

Al Massira reservoir: on the brink of collapse

Here, Al Massira has been selected for an in-depth analysis, as it is one of Morocco’s largest reservoirs and has witnessed the most drastic reduction in water extent, as shown in the lower-left plot of Fig. 6. The images highlight the dramatic decrease in water extent over time, with a significant decline observed particularly after 2020, as indicated by the diminishing cyan-colored areas representing water. This visual evidence underscores the critical water scarcity issues faced by the region, with Al Massira approaching critically low levels of water storage, reaching 3% as recorded by water resources agencies. Furthermore, based on data provided by the water ministry in early 2024, it was revealed that by August 2024, Al Massira had been operating at barely around 1% of its capacity, thereby being almost completely depleted. Even this formerly extensive reservoir has become a relative shadow, which underlines the severity of the region’s water crisis.

Fig. 6
figure 6

Temporal evolution of the water mask for Al Massira Reservoir from April 2017 to April 2024. The background was taken from Sentinel-2 cloud-free images.

Full size image

Although evaporation accounts partly for water loss in the Al Massira dam, it can never be considered an exclusive factor. With 80% of Morocco’s irrigated land in the Oum Er-Rabia region, Al Massira is essential for irrigating the extensive agricultural areas. During the agricultural growing season, significant volumes of water are diverted from the reservoir to sustain crop development. Indeed, the Green Morocco Plan (GMP) emphasizes the importance of utilizing water from reservoirs throughout Morocco to support the expansion of agricultural practices76. However, the rapid expansion has put even tighter pressure on water resources.

The GMP represents a major initiative to promote Moroccan agricultural development and modernization through two significant pillars: promoting competitive, large-scale farming and supporting smallholder farmers in marginal regions. The plan aimed to mobilize 147 billion dirhams over 12 years, with 75 billion dirhams allocated to modern agriculture (Pillar 1) and 20 billion dirhams for solidarity agriculture (Pillar 2)77. Pillar 1 focused on high-value crops, mainly represented by citrus, olives, and vegetables, while Pillar 2 targeted poverty alluviation, especially among communities in rural areas. Around 40% of the investment has been presented as governmental subsidies, focusing on increasing agricultural productivity, primarily through the expansion of drip irrigation areas, which increased from 155,000 hectares in 2008 to 700,000 hectares by 2020. Although agricultural development has contributed relatively to employment and GDP growth, it has also led to regional disparities and environmental concerns, particularly regarding water overexploitation, with annual water withdrawals exceeding the renewable supply (Kmoch et al., 2024; Asedrem, 2021). Despite the increased investment, small-scale farmers and rural communities received limited benefits, thus highlighting issues concerning the long-term viability of the results achieved as part of this program78. This highlights the vital need to balance increased agricultural production with the preservation of critical water resources79. Indeed, it is a delicate interplay between ensuring food security and maintaining ecological balance, a challenge that Morocco, like many arid and semi-arid regions, grapples with in the face of climate change and increasing population demand80. For instance, Casablanca, Morocco’s largest city, relies on the Al Massira dam as its primary drinking water supplier. However, the reservoir has significantly reduced over the past seven years.

Explaining the changes: expanding agriculture

Morocco has increasingly shifted towards growing water-intensive crops, such as olives, citrus fruits, avocados, and tomatoes (Fig. 7)11,80 . This shift is exacerbating the country’s already severe water issues. The expansion of agricultural areas is striking, with avocado production increasing more than fivefold from 2000 to 2024 (Fig. 7). Each crop requires between 1,000 and 1,300 mm of water to grow (ref). Citrus fruit production has also doubled, requiring 900 to 1,200 mm of water. For example, orange production jumped from 870,000 tons in 2000 to over 1.2 million tons in 2022. Tomatoes, including cherry tomatoes, have also shown a significant increase in production, as revealed by FAO data (Fig. 7). These increases are primarily due to government policies that encourage the export of high-value crops, making Morocco a key exporter to international markets. However, while Morocco exports these water-intensive crops, it still has to import a significant amount of staple foods because domestic production is unstable80.

Fig. 7
figure 7

Trends in agricultural production of key crops in Morocco from 1990 to 2024. The figure shows the production levels (in tons) for Wheat, Citrus Fruit (Total), Tomatoes, Bananas, Peaches and Nectarines, and Avocados.

Full size image

The Oum Er-Rabia region exemplifies Morocco’s challenges in balancing agricultural demands with limited water resources. Despite receiving an average annual precipitation of 360 mm, the region’s farms require substantial water for irrigation, particularly for water-intensive crops. This highlights the challenge of cultivating such crops in a country with limited water resources. For instance, wheat, which requires significantly less water, illustrates this more general issue, given that wheat is a staple component of the Moroccan diet, consumed daily in the form of bread. Its production fluctuates significantly in response to rainfall, resulting in substantial drops in wheat yields, which forces Morocco to increase imports to meet demand (Fig. 7). This dependence on rainfall makes wheat production critical and uncertain within Morocco’s agricultural system. Future investigations could integrate hydrological and evapotranspiration models to quantitatively assess the exact contribution of agriculture to water depletion, offering a more detailed understanding and thus aiding in the formulation of sustainable water management practices81.

The government’s commitment to intensive agriculture relies on sufficient water supplies from both surface and groundwater sources. The government plan was based on the availability of approximately 18 billion cubic meters of water. Still, due to persistent droughts, this quantity has drastically decreased, particularly in light of the agricultural sector’s significant contribution to economic growth80. However, these policies exacerbate imbalances and further deplete groundwater reserves, thus underpinning local market instability. While insufficient progress has been made regarding groundwater preservation and management, a considerable gap remains between communities with reliable access to water and those without such access to groundwater. This again highlights the pressing need for sustainable water management to align with Morocco’s agricultural demands.

Towards action: the need for more outstanding efforts

The current state of Moroccan reservoirs is highly alarming, with water levels declining significantly. This situation is being exacerbated for surface and groundwater by excessive water abstraction to satisfy the growing agricultural demand. Consequently, groundwater levels nationwide are dropping significantly. For instance, in the Mejjat region of the Haouz plain, located in the Tensift basin, excessive groundwater withdrawal has led to a decline in groundwater levels reaching up to 5 m per year since 201611. Moreover, in several regions, the water table has declined by up to 50 m between 1980 and 202111. These combined water scarcities require immediate intervention. Considering these challenges, it is imperative to reassess current policies and practices, particularly in water-dependent regions.

Additionally, promoting efficient irrigation practices and techniques, such as drip irrigation, and encouraging crop diversification can help optimize water usage and reduce strain on the already diminishing water reserves. Furthermore, a comprehensive water management strategy should prioritize conservation measures and explore alternative water sources. This includes investing in water recycling and desalination projects and implementing strict water conservation policies at the individual community levels.

To support these efforts, robust monitoring systems and data collection initiatives should be established to continually assess water availability, usage, and the impact of conservation measures. This data-driven approach will provide stakeholders and policymakers with valuable insights to inform their decisions and implement effective water management strategies. Moreover, supporting small family farms could have been crucial for socio-economic development, promoting food sovereignty, and more efficient water use. However, economic and political interests have driven the Moroccan state to prioritize large-scale commercial agriculture instead.

Conclusion

The present study reveals the critical status of surface water areas in Moroccan reservoirs from 2018 to 2024. A specific decrease was observed between 2021 and 2023, attributed to the ongoing drought in Morocco that began in 2017. The overall trend is heavily influenced by reduced precipitation and climatic variability, with an average annual precipitation decline of 7.77 mm per decade exacerbating water shortages across the country. The analysis of Sen’s slope highlights regional disparities, with certain reservoirs, Al Massira and Bin El Ouidane, experiencing severe reductions. In contrast, others in northern Morocco, such as Hassan II and Sidi Chahed, showed more stable water resources.

Additionally, the expansion of water-intensive crops, driven by government policies, has further exacerbated the status of water resources, particularly in central and southern regions, which rely on reservoirs for both agriculture and drinking water supply. The situation is especially critical for reservoirs such as Al Massira, which has approached severe water storage levels (less than 3% since 2023), primarily due to the combined effects of reduced precipitation and over-extraction for irrigation. This reflects broader national concerns, as the expansion of agriculture, particularly under the Green Morocco Plan, has led to unsustainable water use. The growing water demand from agriculture, combined with ineffective water management strategies, is depleting both surface and groundwater resources, deepening Morocco’s water crisis.

Similar water crisis issues have been observed worldwide, including in Chile, India, and the USA (30, 31). In Chile, the overextraction of groundwater for agricultural use in the Atacama Desert has raised concerns about long-term sustainability. Meanwhile, states like California have faced severe droughts in the USA, leading to strict water conservation measures and debates over water rights. These crises highlight the global challenge of balancing agricultural needs with sustainable water management. Addressing these challenges requires a balanced approach that reconciles agricultural expansion with the preservation of water resources. There is a critical need for more efficient water use, promoting efficient irrigation practices and crop diversification, as well as expanding alternative water sources, such as desalination. Ultimately, a comprehensive, data-driven water management strategy is essential to mitigate the impacts of climate change, ensure economic development, and achieve long-term water security in Morocco’s semi-arid regions.

While this study spans 2018–2024, future research would benefit from extending this timeframe to capture long-term trends and the cumulative impacts of climate change and agricultural policies. This could be achieved by integrating additional satellite datasets, such as Landsat, with its historical archive dating back to the 1980s, or MODIS, which offers high temporal resolution data ideal for analyzing long-term water dynamics and climate variability. Platforms like Google Earth Engine (GEE) can facilitate the processing of these large-scale datasets. For instance82, demonstrated how GEE’s JavaScript API significantly enhances surface water dynamics monitoring in drought-prone Mediterranean regions. Similarly83, highlighted the value of remote sensing in evaluating three decades of land-use and land-cover changes in the Ziz Oases, an environmentally vulnerable region in Morocco’s Pre-Saharan area.