The changes in LWA in the TMA are often considered accurate and sensitive representations of climate parameter changes and profound modifications in LU practices. In three decades, the Imouzzer and Aoua depressions have experienced a progressive development of rosaceous orchards. The spatiotemporal evolution of irrigated areas in the TMA has led to notable transformations in landscape structures. These changes in LU practices have coincided with long periods of severe drought that have affected Morocco since the 1980s (Barakat and Handoufe 1997; Stour and Agoumi 2008).
3.2.1. Drought severity
Precipitation Variability
In this study, the variability and trend of precipitation over an 80-year period are highlighted through the analysis of data series from two representative climate stations (Ifrane and Sefrou). The pluviometric data presented in Fig. 7 show the variation of precipitation in the stations of Ifrane and Sefrou. The amounts of precipitation recorded between 1935 and 2015 vary from one station to another and from one year to another, with the highest values recorded at the Ifrane station. Thus, Fig. 7 highlights a strong seasonal contrast in precipitation. The lowest values are concentrated in the summer period. This period coincides with the increased pressure on water resources for the irrigation of agricultural areas in the depressions of the TMA. Seasonal precipitation is extremely variable. Overall, the highest precipitation values have been recorded in winter, while the lowest values occur in summer.
Standardized Precipitation Index (SPI)
The SPI allows measuring the intensity and severity of drought. The selection of the period for calculating the SPI is precisely defined by Guttman (1999); short-term durations can be important for agronomic studies, while very long-term durations are suitable for hydrological issues. The calculation of SPI for Ifrane and Sefrou stations over a period of 12 and 24 months allows showing wet and dry periods. The results presented in Figs. 8 and 9 demonstrate that wet and dry periods are more clearly visible for SPI 24 months (Fig. 8) compared to SPI 12 months (Fig. 9). For the stations of Ifrane and Sefrou, two major periods have been distinguished (Fig. 9). The first is characterized by a remarkable dominance of wet to very wet years of long duration, with positive anomalies exceeding 2. In the second period, a continuous drought was observed, with long periods of severe to very severe droughts (negative anomalies reaching values greater than − 2) and short wet spells. The frequency and intensity of drought increased significantly after 1980. The increase in the number of long-lasting droughts from the 1980s has strongly influenced the water area of the lakes. During wet periods, the lakes in the TMA show significant extension of their water area. However, an alarming decrease in the LWA, or even total drying during periods of severe drought.
Nicholson Rainfall Index (RI)
The analysis of pluviometric data at the Ifrane station between 1935 and 2015 indicates a clear alternation of wet and dry periods (Fig. 10). The pluviometric index clearly shows the number of wet years (33 years) and deficit years (47 years) over a period of 80 years. The station recorded a long period of drought from 1934 to 1954. This period was followed by a new upward trend in precipitation until 1971. From 1972, the number of deficit years saw a remarkable increase, with 29 dry years compared to 15 wet years, indicating a trend towards drought in the climate over the last decades. As for the Sefrou station, we have identified two major periods. The first period, spanning from 1935 to 1979 (45 years), is characterized by an alternation of wet years (29 years) and dry years (16 years) with a remarkable predominance of wet periods. However, the second period extends from 1980 to 2017 (35 years) and is distinguished by a remarkable decrease in wet years. The dominance of deficit years is perfectly visible in the RI (26 years) compared to 9 years for wet years. Thus, within the second period, we observed a short wet period which extends over three years from 2009 to 2011. The comparison between the two periods highlights a significant decrease in rainfall, with 16 deficit years for the first period and 26 deficit years for the second period. While until 1980, dry years were less frequent, they have become the norm for almost 40 years, indicating that this climatic drought condition has likely become structural.
In parallel with this abrupt change in precipitation and the dominance of long periods of drought since the 1980s, temperatures have recorded a significant increase in positive anomalies, as highlighted in the official reports of the Intergovernmental Panel on Climate Change (IPCC 2007, 2013). The trend of decreasing precipitation, rising temperatures, and the progressive expansion of irrigated areas in the TMA have contributed significantly to the amplification of hydrological deficits. Locally, this is manifested by the decline in groundwater levels and, consequently, the drying up of springs, reduced river flows, and alarming depletion of lakes, especially in recent years.
3.2.2. LU changes
Studies focused on the Middle Atlas confirm that this region of Morocco was primarily used for pastoral activities (Amyay et al. 2000; Badidi 1995; El-Jihad 2016; Jennan 1986; Tag 1996; El-Bouhali 2023) with a limited area devoted to rainfed and irrigated crops. However, with population growth, increased connectivity to other regions, the desire to exploit natural resources, and government subsidies, these areas have witnessed significant rural development, resulting in profound landscape changes. This includes the expansion of irrigated agriculture and orchards at the expense of grazing lands and rainfed crop areas. The rates of changes, the processes implemented, and the actors involved in this dynamic have not been the same throughout this period (El-Bouhali 2023).
Over the past decades, the Imouzzer and Aoua depressions have witnessed a continuous extension of agricultural practices based on irrigation. The LU map derived from the Landsat image of August 2022 clearly shows a significant increase in irrigated areas compared to the year 1985 (Fig. 11). The development and arrangement of land for irrigation have expanded in all directions. Irrigated lands are now found on the slopes of depressions, marshlands, grasslands, and even at the edges of forests. The profit generated by irrigated crops, government incentives, and the influx of external capital into the region are the driving forces behind this development. The irrigation of these new farms is provided exclusively by groundwater. The water extraction from the aquifer in these areas withdraws significant volumes of water.
The mapping and quantification of LU in the depressions of Imouzzer and Aoua (Fig. 11 and Table 3) have highlighted a significant landscape dynamic characterized by a significant increase in irrigated agricultural areas. Between 1985 and 2022, the area of irrigated land increased from 1300 hectares to 7070 hectares (+ 7.16% of the total area), representing a growth of 542% over 37 years. This extension of irrigated areas often occurred at the expense of uncultivated lands (pasturelands), which decreased from approximately 32,000 hectares to 26,000 hectares, experiencing a reduction of about 6000 hectares (-7.44% of the total area). The total water surface of the lakes in this area significantly decreased, from approximately 205 hectares in 1985 to only 27 hectares in 2022, resulting in a decrease of 178 hectares.
Table 3
Evolution of LU (ha) from 1985 to 2022
LU classes | Surface in |
1985 | 2022 | 1985–2022 |
ha | % | ha | % | ha | % |
Irrigated crops | 1304 | 1.62 | 7071 | 8.78 | 5767 | 7.16 |
Forests | 46948 | 58.29 | 47100 | 58.48 | 152 | 0.19 |
Bare land | 32050 | 39.79 | 26055 | 32.35 | -5995 | -7.44 |
Lake | 205 | 0.25 | 27 | 0.03 | -178 | -0.22 |
Habitats | 33 | 0.04 | 287 | 0.36 | 254 | 0.32 |
Between the two dates, the depressions of Imouzzer and Aoua have experienced a significant landscape transformation, primarily characterized by a progressive increase in irrigated agriculture. The shift of population activities towards irrigation and the adoption of modern water exploitation techniques have led to the regression of traditional society. Alongside the extension of irrigated areas, the demand for irrigation water has increased, exerting significant pressure on the groundwater resources of the TMA. The consequences of modifications in LU, within the context of CC, have had a striking impact on the water resources in the study area. The intensification of irrigation and the continuous increase in water extraction downstream of Aoua lake and in the vicinity of Ifrah lake have greatly contributed to the disruption of the hydrological regime. Consequently, the complete drying of Aoua lake for extended periods (2018–2022) reflects the extremely critical condition of the groundwater level, characterized by a significant and widespread decline. Although this decline dates back to the mid-1990s, its magnitude has become alarming today.