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Climate change and its impacts on groundwater resources in Morocco: The case of the Souss- Massa basin

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The study reviews the present tools and results which deal with the identifi cation and prediction of the impacts of climate change (CC) on groundwater resources in Morocco. The paper describes the available data, which could be used to indicate the CC effects on groundwater in the Souss-Massa basin in southwestern Morocco. The average of rain ranges from 100 mm/a in the plains to 600 mm/a in the Atlas Mountains. Precipitation data indicate an overall decrease during the three last decades. Water resources show an important depletion in surface and sub-surface. The recurrent droughts and decreases in recharge directly affect the groundwater level. This is coupled with increased groundwater abstraction and explains the water crisis witnessed in the area, which is predicted to be particularly affected by CC in the future. Chemical and isotopic tracers indicate a degradation of water quality with increasing salinity originating from seawater intrusion, evaporates and anthropogenic pollution (fertilizers, waste water). By this result, these natural tracers confi rm the fact that CC impact directly on groundwater in the Souss-Massa basin. It was argued that the heavily exploited aquifer along the coastal areas is more vulnerable to marine intrusion given the relatively longer residence time of the water and salinization processes in this part of the aquifer. The data compiled in this study provide the framework for a comprehensive management plan in which water exploitation should shift toward the eastern part of the basin where current recharge occurs with young and high quality groundwater. Any variation in the natural recharge can affect immediately the capacity of groundwater to meet the demands of humans and ecosystems in this area. These results should be taken in consideration for the future water management in the country.
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CHAPTER 8
Climate change and its impacts on groundwater
resources in Morocco: the case of the Souss- Massa basin
Lhoussaine Bouchaou, Tarik Tagma, Said Boutaleb,
Mohamed Hssaisoune & Zine El Abidine El Morjani
ABSTRACT
The study reviews the present tools and results which deal with the identifi cation and prediction
of the impacts of climate change (CC) on groundwater resources in Morocco. The paper
describes the available data, which could be used to indicate the CC effects on groundwater in
the Souss- Massa basin in south- western Morocco. The average of rain ranges from 100 mm/a
in the plains to 600 mm/a in the Atlas Mountains. Precipitation data indicate an overall decrease
during the three last decades. Water resources show an important depletion in surface and sub-
surface. The recurrent droughts and decreases in recharge directly affect the groundwater level.
This is coupled with increased groundwater abstraction and explains the water crisis witnessed
in the area, which is predicted to be particularly affected by CC in the future. Chemical and
isotopic tracers indicate a degradation of water quality with increasing salinity originating
from seawater intrusion, evaporates and anthropogenic pollution (fertilizers, waste water). By
this result, these natural tracers confi rm the fact that CC impact directly on groundwater in the
Souss- Massa basin. It was argued that the heavily exploited aquifer along the coastal areas is
more vulnerable to marine intrusion given the relatively longer residence time of the water
and salinization processes in this part of the aquifer. The data compiled in this study provide
the framework for a comprehensive management plan in which water exploitation should shift
toward the eastern part of the basin where current recharge occurs with young and high qual-
ity groundwater. Any variation in the natural recharge can affect immediately the capacity of
groundwater to meet the demands of humans and ecosystems in this area. These results should
be taken in consideration for the future water management in the country.
8.1 INTRODUCTION
8.1.1 Purpose and scope
In spite of its geographical situation on the Atlantic and Mediterranean coast, Morocco
is one of the most arid areas of the world; it experiences highly variable rainfall and
recurrent droughts. The limited water resources are threatened by increasing demands
and accelerated quality degradation. In addition, the Intergovernmental Panel on
Climate Change (IPCC) predicts in its 4th Assessment Report that “Annual rainfall is
likely to decrease in much of Mediterranean Africa and northern Sahara, with the like-
lihood of a decrease in rainfall increasing as the Mediterranean coast is approached
(IPCC 2007) Chapter 11, p. 866). The fact that climate is changing has become increas-
ingly clear over the past decade. This prediction is based on several climate models that
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130 Lhoussaine Bouchaou et al.
simulate global and regional mean precipitation. While the multi- model predictions show
confl icting results for some areas, in the Mediterranean and Northern Africa the multi-
models show consistent results of signifi cant reduction in precipitation (IPCC 2007).
The Intergovernmental Panel on Climate Change reports that heat waves have been
increasing towards the end of the 20th century and are projected to continue to increase
in frequency, intensity and duration worldwide (WHO 2009; Baccini et al. 2008; IPCC
2007; Meehl et al. 2007; Robinson 2001). Climate change is caused by the combined
impact of growing human population and economic activities (WHO 2003b). The IPCC
has developed a series of 40 scenarios of plausible future trajectories for population
growth, economic and technological development (IPCC 2000). Each scenario gives esti-
mates for greenhouse gas emission levels, and predicts the changes in the temperature
( Campbell- Lendrum and Woodruff 2007). For example, temperature may be estimated
to increase by 0.54C (scenario B2 – low emission scenario), 0.84C (scenario A1B –
middle emission scenario) or 1.02C (scenario A2 – high emissions scenario) in 2030,
relative to the baseline period (WHO 2009).
Consequently, projections for future renewable water resources in Morocco are
bleak, and climate change coupled with increasing water demands are likely to exacer-
bate the water crisis in Morocco.
The surface water represents two- thirds of the hydro reserves of the country.
From 1967 to 2010 more than 120 large dams were built to increase the storage capacity
from 2.3 billion cubic meters (BCM) in 1967 to 18 BCM in 2004. During the last four
decades the Moroccan water resources development planning has been focusing on
increasing the storage of the country’s surface water resources for an optimal use in
irrigated agriculture, drinking water, industrial supplies, and hydroelectric power produc-
tion. Huge state funds have been invested in the essential infrastructure to control surface
water fl ows. Further capturing and utilization of about two- thirds of the surface water
potential is projected, and a number of major infrastructure projects are in advanced
stages of planning and/or construction.
Due to its large geological diversity, a broad range of aquifers from almost all the
geological periods are present in Morocco. Overall, 32 deep (200 to 1,000 m) and 48
shallow aquifers are tapped in Morocco. The deep aquifers are often not accessible due
to the high economic cost of drilling, whereas the shallow aquifers are more accessible,
but also more vulnerable to climate change, pollution and evaporation. Unfortunately,
a comprehensive model for evaluation of the full potential and yield of these aquifers
has not been completed and several unresolved questions for the potential yield of these
aquifers remain. Overall, in the 80 already identifi ed aquifers, the potential sustainable
groundwater yield under feasible economical and technological constraints is estimated
at 4 BCM/a (Bzioui 2004).
The present study focuses on the Souss- Massa basin which is intensively studied.
This paper reviews literature and the observed aspects showing the current state water
resources in Morocco through the case of the Souss- Massa basin under the pressures of
demographic growth and climate change.
The objectives of the study are to examine: (i) whether any trends can be identifi ed
from observed rainfall and temperature data in the region and how can be related to CC;
and (ii) what are the impacts of the projected changes in temperature and precipitation
on groundwater, more specifi cally, what impacts these changes will have on recharge,
renewal and water quality of the reserves.
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Climate change and its impacts on groundwater resources in Morocco 131
8.1.2 Description of the study area: the Souss- Massa basin
The Souss- Massa basin, located in south- western Morocco, is one of the country’s most
important hydrological catchments with an area of 27,000 km2 (Fig. 8.1). Elevations in
the catchment range from 0 m (Atlantic Ocean) to 4,168 m (Toubkal peak in the High
Atlas Mountains). The plain area lying between 0 and 700 m above sea level (m.a.s.l.)
covers about 5,700 km2 and contains the groundwater reservoir, while the remaining part
is mountainous.
The Plio- quaternary formations of the Souss- Massa plain situated between the High
Atlas Mountain in the north and Anti- Atlas in the South (Fig. 8.1) represent the most
important aquifer in the southern High Atlas Mountain in Morocco. The economy of the
Souss- Massa is primarily based on agriculture, sea fi shing and tourism. Surface water and
groundwater resources are used both, intensively and extensively throughout the area.
Overexploitation, aridity of the climate and the various sources of pollution in the
area threaten both the quantity and quality of the hydrous reserves. In order to improve
the management of these precious resources, several studies have been carried out dur-
ing the last years to reach a better understanding of the hydrological functioning of the
aquifer system (Boutaleb et al. 2000; Ekwurzel et al. 2001; Hsissou et al. 2002, Ahkouk
et al. 2003; Dindane et al. 2003; Krimissa et al. 2004; Bouchaou et al. 2005) using differ-
ent approaches and tools. The shallow aquifer in the plain is sensitive to climate change
and several sources of pollution (wastewater, solid discharges, and agricultural fertilizers).
The rivers of the region, locally called “Oued”, have an intermittent fl ow regime,
because the dry season is typically very long (6 to 8 months. The main oueds in this
basin are Souss and Massa, which receive important infl ow, in particular from the rain-
laden High Atlas Mountains in the North and the Anti Atlas Mountains in the South.
This infl ow coming from a high altitude is infi ltrated in the piedmont area and in the
beds of rivers which consist of high permeable conglomerates. The shallow aquifer of
the Souss- Massa plain is the main resource for drinking, irrigation and industrial water
in the region.
Figure 8.1. Runoff network and location of dams in the Souss- Massa basin.
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132 Lhoussaine Bouchaou et al.
8.1.3 Methodology
The paper describes the available meteorological time series data, which could be used
to predict CC impacts in a hydrological basin under arid climate in Morocco. The paper
reviews the existing results and literature on the impacts of climate change (CC) on water
resources through the quantity and quality degradation in the study area.
8.1.4 Relevance to GRAPHIC
The current estimated actual water consumption in Morocco is 11 BCM per year includ-
ing 3.5 BCM per year from groundwater, of which approximately 90 percent is used for
agriculture. The ratio of renewable water resource to the population in Morocco is less
than 1000 m3 per person per year, and thus Morocco is defi ned as “water stressed” coun-
try. Due to population growth it is estimated that by 2030, 35% of the population will have
reduced access to water and will be below the level of severe stress conditions of 500 m3
per person per year. Thus, growing scarcity is anticipated due to rising demands resulting
from expansion of irrigated areas and urban development coupled with diminishing water
resources. Morocco is already ranked on the 155th position on a scale of 180 countries,
in terms of available fresh water resources. The current overexploitation of the aquifers
results in a serious decrease of groundwater levels and degradation of water quality, in
particular increasing salinity in all groundwater basins, which reduces potable water avail-
ability. In some of the more intensively exploited coastal aquifers groundwater levels have
declined and saltwater intrusion migrates inland. In other basins high salinity of ground-
water originating from human activities (agriculture, wastewater...) has become a limiting
factor for sustainable management of water resources in Morocco. Water defi ciency and
water quality degradation have important implications for future economical development
and social and political stability in Morocco, as water authorities are already struggling to
distribute and provide potable water to the domestic and agricultural sectors.
Sustainable water supply is an essential element of Morocco’s economy and pros-
perity. In addition, tourism, which is heavily dependent on water supply, is an important
economic component in southern Morocco. Degradation of water quality in the region might
reduce agricultural production and the ability to sustain the growing tourism industry in the
region. Inadequate water supply might also increase the competition between the rural and
urban societies over diminishing water resources. Mitigation of a water crisis and saliniza-
tion phenomena is therefore a critical factor for economical growth and political stability
in Morocco.
The Souss- Massa basin is a good example in Morocco showing quantitative and
qualitative aspects of the combined impacts of CC and human activities on groundwater
resources. This local case study compares the climate change impacts in a small scale
basin with global climate change models. As such, this case study will contribute to the
development of scenarios within GRAPHIC.
8.2 RESULTS AND DISCUSSION
An attempt has been made to examine whether the climate is actually changing through-
out the study area. This has been done by trend analysis of the available time series of
rain and changes affecting the quantity and quality of groundwater. The groundwater
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Climate change and its impacts on groundwater resources in Morocco 133
level in the Souss- Massa aquifer is closely related to fl uctuations in precipitation and
shows an inter- annual variation according to the seasonal regime.
8.2.1 Rainfall variation
In general, precipitation in Morocco decreases from the north to the south and from the
west to the east. The north- western section receives the greatest quantities of precipitation.
The annual average rainfall reaches more than 1,000 mm in the northern Rif Mountains
and less than 300 mm in most other parts of Morocco. The rainwater potential shows an
annual average of 150 BCM in which 15% of the land surface receives more than 50%
of precipitation. The rainfall amount largely fl uctuates from 50 BCM in a dry year to
400 BCM in an exceptionally rainy year. In an average year, the potential renewable water
is about only 20% of total precipitation; that is 29 BCM including 19 BCM of surface
water. Taking into account potential storage sites and groundwater development possibili-
ties, only 22 BCM are annually potentially accessible, 18 BCM from surface water and
4 BCM from groundwater (Agoumi 2003; Bzioui 2004; Agoussine and Bouchaou 2004).
Figure 8.2 shows the spatial variation of rainfall in Morocco, with a decrease from the
north to the south and indicating the low precipitation in major part of the country.
The climate in the Souss- Massa basin is semi- arid to arid, the rainy season extending
from November to March and the dry season from April to October. Locally, the rain-
fall varies in time and space (Fig. 8.2 and Fig. 8.3), ranging from 200 mm/a in the plain
(mean altitude: 460 m.a.s.l.) to 600 mm/a in the mountains (altitude 700 m.a.s.l.). The
long- term mean annual precipitation decreased in 20 years from 343 mm in Aoulouz
(700 m.a.s.l.) to 232 mm in Taroudant (500 m.a.s.l.). A very clear decrease is observed
in the High Atlas Mountains in the north of the area (Tamri) to the south (Massa station)
where the monthly rainfall exceeds rarely 100 mm/a (Fig. 8.2).
The variation of rainfall is very important in time and space showing a clear decrease
from the mountains to the plains and towards the desert zone in the south. The monthly
values indicate a decrease over the last three decades after the most important intensity
during the 1960’s. The variation shows a clear seasonal irregularity (Fig. 8.3).
8.2.2 Temperature and heat waves
The spatial distribution of the intensity levels of heat wave hazard for Morocco within the
Mediterranean context indicates that a large part of the country shows a high temperature,
mainly in the south (Fig. 8.4).
According to the seasonal variation using 12-month moving average, the monthly
values of the temperature indicate an increase during the last decades since the 1970’s
(Fig. 8.5). The inter- annual evolution shows the same trend with strong increase in
temperature. Mean annual temperature is plotted versus time. The solid black line rep-
resents a locally- weighted polynomial regression using kernel smoothing (Fig. 8.6). The
bandwidth was selected using the Sheather- Jones method (see the package SiZer for R at
http://www. r- project.org for more detail). The grey band represents the 95% confi dence
intervals.
In conclusion, the area experiences high inter- annual variability of the scarce rainfall
distribution making it most vulnerable to climatic change. Consequences of climate
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134 Lhoussaine Bouchaou et al.
Figure 8.2. Altitude and rainfall distribution (Elmouden et al. 2005).
Figure 8.3. Monthly variation of precipitation in two main stations (Agadir and Taroudant) in the
Souss- Massa basin.
change are expected to have major implications on agricultural production and tourism
in the area. In this context, increased variability of rainfall and temperature in the region,
associated with climate variability and change, implies increased vulnerability. This is
likewise true for changes in land use, agricultural production and other climate variability
hat affects and responds to the water resources. These changes are often amplifi ed by an
increase in population numbers or density or decreasing water supply.
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Climate change and its impacts on groundwater resources in Morocco 135
Figure 8.4. Spatial distribution of the intensity levels of heat wave hazard for Morocco (WHO 2011).
Figure 8.5. Seasonal variation of the monthly temperature in Agadir station: moving average.
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136 Lhoussaine Bouchaou et al.
Figure 8.6. Seasonal variation of the temperature in Agadir station: inter- annual trend evolution.
The solid black line represents a locally- weighted polynomial regression using kernel smoothing.
8.2.3 Impacts on groundwater level
As a consequence of decrease in precipitation and demographic pressures, groundwater
pumping has been accelerated and the exploitation of the aquifers has intensifi ed.
Subsequently, wells were deepened and equipped with more powerful pumps, allowing
for much deeper resources like the Turonian aquifer to be exploited. As a result, ground-
water tables declined signifi cantly since 1990 (ABHSM 2004).
A number of problems associated with increasing water scarcity and recurrent
and extended droughts have been noticed in the Souss area particularly in the past few
decades (Bouchaou et al. 2008; Tagma et al. 2009). The extended drought periods are
often thought to be related to climate variability arising and can be indicators of CC. The
studies supporting these observations in the area are being carried out. Manifestations
of water scarcity include, among others, an alarming decline of both surface and
groundwater resources, which resulted in the introduction of strict water control by the
hydraulic agency. An increasing number of private wells were developed to circum-
vent these restrictions (Fig. 8.7), which in turn resulted in a further adverse impact on
the groundwater table by increasing the extractions (Fig. 8.7). Increased water shortage
during the last 20 years, often perceived to be caused by recurrent droughts led to the
cancellation of the plans to extend the area irrigated by the main dams in the region.
There are concerns that the recurrent droughts will further deplete the available water
resources.
Figure 8.8 indicates the impact of rainfall variability in the basin on groundwater
quantity. The reaction of the water table to the rainfall recharge is very variable in
space and time within the basin. The major trend indicates an overall decrease in water
resources, due to the combination of the natural decreased recharge and human activi-
ties (extractions). This depletion affects directly the water availability per capita in the
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Climate change and its impacts on groundwater resources in Morocco 137
Figure 8.7. Wells and boreholes in Souss- Massa plain aquifer (more than 25,000 wells).
Figure 8.8. Decrease in water table during the last decades obtained from a monitoring of a
representative well located in the middle of the Souss- aquifer.
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138 Lhoussaine Bouchaou et al.
country and in particular in the Souss- Massa basin. According to water monitoring
and simulation established by hydraulic department, the scenario for the 2020 predicts
a possible water crisis in the area (Fig. 8.9).
8.2.4 Impacts on groundwater quality
The depletion of groundwater level induced by limited recharge and overexploitation
has induced degradation of water quality in the Souss- Massa plain aquifer. The differ-
ent chemical and isotopic data used in some studies carried out in the area (Boutaleb
et al. 2000; Hsissou et al. 2002; Bouchaou et al. 2008; Tagma et al. 2009) indicate that
salinity of groundwater originates from multiple sources and not only from seawater
intrusion as previously thought. These studies have revealed a complex hydrogeological
system in which several sources of salinity have been identifi ed, including seawater
intrusion, entrapped saline groundwater within the aquifer, saline water derived from
salt dissolution, and infi ltration of agricultural return fl ows. The stable isotope data also
indicate that the Souss- Massa shallow aquifer is highly infl uenced by the contribution of
recharge water from the High Atlas Mountain, which has a high rainfall, particularly in
its upstream part along the Upper Souss plain. The results of age estimates based on 3H
and 14C data suggested that relatively old groundwater is practically mined at some wells.
This indicates that the Souss- Massa basin is very vulnerable to contamination processes,
and the rates of salinization (e.g. seawater-intrusion) or anthropogenic contamination
1970
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1975 1980 1985 1990 1995
Year
Morocco
m3/capita/y
Souss-Massa
2000 2005 2010 2015 2020
Figure 8.9. Scenarios evolution of water availability in Morocco and in Souss- Massa region
(ABHSM 2008).
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Figure 8.10. Spatial variation of salinity (2004) expressed in mg/L as the total dissolved solids (TDS) in groundwater of the Souss- Massa basin (Tagma
et al. 2009).
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Figure 8.11. Spatial variation of nitrate contents (2004) in groundwater of the Souss- Massa basin (Tagma et al. 2009).
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Climate change and its impacts on groundwater resources in Morocco 141
agricultural return fl ow) are faster than natural replenishment of the aquifer. According
to the decrease of the aquifer recharge, the renewal of the groundwater in the reservoir is
very low which minimises dilution in the aquifer. Two major areas were distinguished in
the basin (Fig. 8.10 and Fig. 8.11): (i) The Souss upstream part with a high water quality
and modern recharge, and (ii) downstream in coastal areas with low water quality derived
from different salinity sources and long residence time of groundwater, increased by the
low replenishment. This is a refl ection of climatic change and pressure of human activi-
ties. Intense agricultural activities using fertilizers highly affect the water quality with
high nitrate contents (Fig. 8.11). The contamination is highlighted mainly in irrigated
perimeter. This result means that we cannot focus only on the quantitative understand-
ing of CC impacts that can be also cause deterioration of the groundwater quality
in the country. This hides the potential impacts of CC in small scale on the individual
river basins or irrigation schemes. Without serious precautions, the degradation of the
quality can induce a water crisis in the future. The hydrochemical and isotopic tracers
indicating the possible future climatic change in the Souss- Massa basin can be used to
quantitatively assess the impacts of CC on water availability and, consequently, to for-
mulate adaptation strategies.
8.3 POLICY RECOMMENDATIONS
Precipitation in the Souss- Massa basin has high variability, as typical for semi- arid
climates. Several global- scale studies have concluded that the Mediterranean will be one
of the regions most signifi cantly affected CC in the future, in terms of decreasing precip-
itation and increasing temperatures. This will eventually lead to decreasing availability
of water resources. The case of the Souss- Massa basin confi rms these global- scale nd-
ings at the local level. The rain stations indicate growing rainfall defi cits, possibly related
to CC, especially over the High Atlas Mountains, which are the main source of water
for the entire hydro- system in southern Morocco. The hydrology of the upstream basin
and the High Atlas Mountains supplying the main dams and the aquifer in the system
has not been assessed suffi ciently under present- day conditions, neither for future sce-
narios of CC. The implications of future water availability scenarios for irrigation system
management (diversifying cropping pattern, expanding sprinkler irrigation, improving
institutional aspects, conjunctive use of surface and groundwater) are not yet well exam-
ined. Obviously, continued water utilization in the coastal and near- coastal areas would
further increase the depletion of water resources and degradation of groundwater quality.
More detailed studies on CC impact on groundwater resources in this region will
be required. The fi ndings of current and future studies should be taken into considera-
tion for the preparation of water management plans. Groundwater abstraction should be
shifted from the heavily populated areas along the coast, which are more vulnerable to
contamination, towards the high quality and renewable water resources along the upper
zone of the basin. This can affect the recharge area in the upstream and limits the con-
tribution supplying the downstream part. Therefore, the application of artifi cial recharge
in the area and improving of the irrigation schemes may help substantially to anticipate
further aggravation of the water resources situation, both quantitatively and qualitatively.
Desalinisation of brackish or sea water can be an option in the cases of crisis. Convincing
the farmers to use the treated wastewater is as important as challenging in the country.
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142 Lhoussaine Bouchaou et al.
8.4 FUTURE WORK
The data generated in this study provide the framework for a comprehensive management
plan in which water exploitation should shift toward the eastern part of the basin where
current recharge occurs with young and high quality groundwater. In contrast, it was
argued that the heavily exploited aquifer along the coastal areas is more vulnerable given
the relatively longer residence time of the water and salinization processes in this part
of the aquifer. What management measures can be implemented in the area in order
to administer the possible impacts of CC and pressures of humanity (overexploitation
and contamination)? The impacts of CC change on snow cover in the Atlas Mountains
that constitute the main recharge area of the basin need to be further assessed. What is the
contribution of snow melt and stream fl ow to groundwater recharge? Options to develop
and operate the water- related infrastructure in the basin under CC conditions need to be
examined. The use of the isotopic tracers is a good tool to estimate the recharge and the
contribution of different component to the groundwater.
A combination of adaptive models should form a good basis to examine how the
future water use in the Souss- Massa area can be optimized. The development of this
assessment methodology will form an integral part of future studies in many basins in
Morocco.
ACKNOWLEDGEMENTS
We thank a lot all the personnel of the Hydraulic Agency Basin of Souss- Massa
(ABHSM) for their help and their cooperation in providing the climatic data base.
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... Additionally, this research focuses on evaluating the level of nitrate contamination in Souss-Massa groundwater by employing multiple technical analyses and identifying the sources that contribute to this contamination. The Souss-Massa basin experiences a semi-arid to arid climate (Bouchaou et al., 2011;Ait Brahim et al., 2017a, b;Abahous et al., 2018). Rainfall occurs during the rainy season from November to March, while April to October marks the dry season. ...
... Rainfall occurs during the rainy season from November to March, while April to October marks the dry season. Rainfall distribution varies across time and space, ranging from 200 mm/year in the plains (average elevation: 460 m) to 600 mm/year in the mountains (elevation 700 m) (Bouchaou et al., 2011;Abahous et al., 2018). The average annual temperature varies between 14 C and 18 C in the High Atlas and the Anti-Atlas, respectively. ...
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Degradation affects many aquifers, impacting both their quantity and quality. Nitrate is the most prevalent groundwater pollutant because it dissolves easily in water and is difficult to fix in soil. This review aims to assess previous research on water quality in the Souss-Massa region (groundwater and surface water), highlight the degree of nitrate pollution recorded in this aquifer, and determine the origins of this contamination. Overall, all dams of the Souss-Massa aquifer showed excellent to good water quality in 2018. In contrast, the rivers indicated a decline in quality during the same year, except at the Aoulouz point, where dissolved oxygen content-reaching up to 4.5 mg/L-was responsible for this degradation. On the other hand, during the 2018-2020 campaign, the Souss aquifer and Chtouka aquifer showed moderate to bad quality due to nitrate concentrations and high mineralization. According to the boxplot diagram of statistical parameters of NO₃⁻ concentration and Nitrate Pollution Index (NPI) collected from previous studies, nitrate pollution recorded in this aquifer occurs in just some wells and not the entire aquifer, and this contamination is basically due to different origins like agricultural fertilizers, domestic wastewater, and manure.
... In the research area, the most prevalent socio-economic activities are fishing, tourism, and agriculture (Attar et al., 2024;Bouchaou et al., 2005;Malki et al., 2016b;Post et al., 2018). According to Bouchaou et al. (2011), SMCA has a semi-arid environment with scorching summers, chilly winters, and little precipitation (less than 200 mm/y). Relief, the Sahara, and the Atlantic Ocean all have an impact on the climate (Malki et al., 2016a;Seif Ennasr et al., 2016). ...
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Study region: The downstream part of the Souss-Massa Basin, Central Western part of Morocco, Northwestern Africa. Study focus: The Souss-Massa coastal area (SMCA) is known for tourism, fishing, and agriculture activities, which require intensive pumping of groundwater. This situation exacerbates aquifer depletion, reduce groundwater quality, and leads to seawater intrusion. Hence, the investigation of vulnerability and risk of seawater intrusion became a priority in the SMCA. An improved GALDIT (composed by nine parameters: groundwater occurrence (G), hydraulic conductivity (A), groundwater above sea level (L), distance from the shore (D), impact of existing status of sea water intrusion (I), thickness of the aquifer (T), river contribution (R), hydraulic gradient (HG), detected and probable seawater intrusion (DPSWI) was applied in the study area using Analytical Hierarchy Process (AHP) and Sensitivity Analysis (SA) to map groundwater vulnerability to seawater intrusion (GWVSI). Moreover, the risk map of seawater intrusion has been created through the combination of the groundwater vulnerability map and the Water Quality Index map (WQI). Our results show that improved GALDIT provides a better overview on groundwater vulnerability to seawater intrusion in comparison to the standard approach. The study area has five levels of vulnerability, very low, low, moderate, high, and very high, which present 15 %, 1.3 %, 19.8 %, 5.5 %, and 58.4 %, respectively. The risk map indicates five levels (low, moderate, high, very high, and extreme), with the southwestern area being the most exposed to the risk of marine intrusion. Finally, the results of this study have been validated using mapped seawater intrusion, and groundwater quality index (GQI sw). Based on the results, we propose a management plan to preserve and manage the coastal aquifer of the Souss-Massa basin.
... The rainfall average was 250-300 mm/year on the plain and around 500-600 mm/year in the mountains (Hssaisoune et al. 2016). The annual mean temperature ranged between 14 and 18°C in the High Atlas and Anti-Atlas Mountains, with a slight difference on the plain, reaching up to 20°C (Bouchaou et al., 2011). The rainfall period extended from November to March, and the dry season could extend up to 7 months (April to October). ...
... This region significantly influences groundwater recharge, as the high elevation and precipitation contribute to the infiltration of water into aquifers (Hssaisoune et al. 2020). The Rif Mountains, located in the northern part of Morocco, also play a vital role in groundwater dynamics through their karst formations, which enhance groundwater flow and storage (Bouchaou et al. 2011). ...
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In this study we evaluate the uranium and radon concentrations in groundwater from the Province of Safi. The samples were collected from 58 wells across five communes and analyzed using the LR-115 type II detector. Results indicate that uranium concentrations ranged from the Limit of Detection (LLD) to 3.73 µg/l, with a mean of 0.72 µg/l, well below the World Health Organization's safe limit of 30 µg/l. Radon levels varied from LLD to 2.39 Bq/l, with an average of 0.60 Bq/l, also below the United States Environmental Protection Agency's limit of 11 Bq/l. The estimated total annual effective dose due to uranium and radon ranged from 3.47 to 18.84 µSv/y, with an average of 7.54 µSv/y, which is significantly lower than the European Commission's recommended limit of 100 µSv/y. This investigation represents the first study of uranium and radon levels in groundwater in the Province of Safi, providing valuable data for future research and public health.
... This decline is attributed to diminished rainfall, overexploitation of groundwater resources, and an imbalanced water distribution system. Moreover, the region's groundwater resources, the linchpin of its water supply, are under severe strain (Bouchaou et al., 2011). Over-extraction has led to notable declines in groundwater levels, particularly in the Sebt El Guerdanne area where the water table has receded to depths of up to 250 m (Hssaisoune et al., 2017). ...
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Groundwater potential in Morocco’s Souss-Massa mountainous basin (SMMB) is being identified using geospatial tools and geological data. We deployed four mathematical models, namely Data-Driven Multi-index Overlay (DMIO), Geometric Average (GA), Support Vector Machine (SVM), and Logistic Regression (LR), to establish data-driven patterns among the nine influencing factors, primarily drainage density, permeability, slope, distance to rivers, elevation, lineament density, distance to lineaments, intersection node density, and rainfall. Based on the Concentration-Area (C-A) fractal approach, the findings of the four models were developed and classified into five levels of potentiality ranging from very low to very high. The regions designated as having high and very high potentialities for the DMIO, GA, SVM, and LR models, respectively, account for 22.44 %, 9.80 %, 19.36 %, and 26.77 % of the overall basin. We validated the models by calculating each model's area under the ROC curve (AUC). The estimated AUC values are more than 70 %, suggesting the model performs well. The four models' performance was compared, revealing that the SVM model outperforms the others. Gravimetric data shows that possible groundwater zones closely coincide with gravimetric lineaments. The findings of this study can provide valuable insights to decision-makers, allowing them to improve decision-making processes and develop holistic groundwater resource management in the Souss-Massa mountainous basin (SMMB).
... This decline is attributed to diminished rainfall, overexploitation of groundwater resources, and an imbalanced water distribution system. Moreover, the region's groundwater resources, the linchpin of its water supply, are under severe strain (Bouchaou et al., 2011). Over-extraction has led to notable declines in groundwater levels, particularly in the Sebt El Guerdanne area where the water table has receded to depths of up to 250 m (Hssaisoune et al., 2017). ...
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Groundwater potential in Morocco’s Souss-Massa mountainous basin (SMMB) is being identified using geospatial tools and geological data. We deployed four mathematical models, namely Data-Driven Multi-index Overlay (DMIO), Geometric Average (GA), Support Vector Machine (SVM), and Logistic Regression (LR), to establish data-driven patterns among the nine influencing factors, primarily drainage density, permeability, slope, distance to rivers, elevation, lineament density, distance to lineaments, intersection node density, and rainfall. Based on the Concentration-Area (C-A) fractal approach, the findings of the four models were developed and classified into five levels of potentiality ranging from very low to very high. The regions designated as having high and very high potentialities for the DMIO, GA, SVM, and LR models, respectively, account for 22.44 %, 9.80 %, 19.36 %, and 26.77 % of the overall basin. We validated the models by calculating each model's area under the ROC curve (AUC). The estimated AUC values are more than 70 %, suggesting the model performs well. The four models' performance was compared, revealing that the SVM model outperforms the others. Gravimetric data shows that possible groundwater zones closely coincide with gravimetric lineaments. The findings of this study can provide valuable insights to decision-makers, allowing them to improve decision-making processes and develop holistic groundwater resource management in the Souss-Massa mountainous basin (SMMB).
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Au Maroc, durant les dernières années, l’eau est une ressource critique, dans laquelle il est urgent d’investir. Alors que l’eau douce, se raréfie dans certaines régions sous l’effet du changement climatique, la pression anthropique et l’augmentation des niveaux de vie ont fait exploser les besoins. Notre zone d’étude, le lac d’Aguelmame Azegza fait partie du bassin versant d'Oum-Er-Rbia, un des grands bassins du Maroc. Il est reconnu parmi les grands réservoirs, qui approvisionnent une grande surface en eau à différentes utilisations. Malheureusement, cette zone subit une forte fragilité et vulnérabilité aux conditions naturelles et aux impacts humains.Dans cette contribution scientifique, nous avons mis l’accent sur l’impact de la variabilité climatique sur le niveau du lac d’Aguelmame Azegza. Nous avons utilisé une approche cartographique, qui se focalise sur le traitement des images satellitaires du lac durant des années différentes, pour faire un suivi de l’évolution de la surface d’eau du lac. En termes de résultats, nous avons trouvé qu’il y a une forte diminution de l’eau de surface d’Aguelmame Azegza durant les dernières années, ce qui va influencer négativement, sur les activités socio- économiques et l’équilibre environnemental et écologique de la zone d’étude.
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Drâa river basin (DRB) is a large arid area encompassing most important oases in the south of Morocco. Climate change, population growth and recently intensive agriculture activity have led to the overexploitation of limited groundwater resources aggravating the problem of water salinization. Therefore, this study aims to assess groundwater quality in the DRB using hydrochemical characteristics from various sources. The complex set of water quality information is simplified into two indicators namely the Water Quality Index (WQI) and Heavy Metal Pollution Index (HPI). Additionally, the suitability of groundwater for irrigation purposes are assessed using sodium absorption ratio (SAR), Residual Sodium Carbonate (RSC) and the permeability index (PI). The results show that the degradation of water quality is related to the high content of sodium and chloride which emerge as the predominant ions along the flow path. Fresher water (Ca-Mg-HCO 3 water type, low WQI and SAR scores), able to sustain local drinking and irrigation needs, are observed in the Upper DRB, while reducing ions excess and adopting agriculture tolerable to salinity become more imperative in downstream oases. The prevalence of hard, igneous and calcareous rocks imparts a general hardness character at a large scale and bicarbonates exceed the permissible limit in 82.30% of samples. However, sodium hazard was not associated with CaCO 3 and MgCO 3 precipitation (low PI and RSC). In some areas, nitrate contents imply anthropogenic contamination from local source of pollution, whereas the concentrations of heavy metals are more associated with the geological setting than anthropogenic activities.
Chapter
Climate change presents a significant challenge in Morocco, where the difficult dynamics of greenhouse gas emissions, meteorological variability, and natural resource degradation intersect. This study offers a comprehensive analysis of these interconnected phenomena, drawing on the multidisciplinary knowledge of climate science, environmental research, and resource management. Using a diverse dataset, including temperature and precipitation data, remote sensing images, and greenhouse gas measurements, we examined the spatiotemporal evolution of climate variables over the past century. Our results showed a complex pattern of temperature fluctuations and precipitation trends, with remarkable increases in maximum and minimum temperatures and a perceptible decline in precipitation over the observation period. In addition, our assessment of greenhouse gas concentrations, particularly CO2 and CH4, highlights the importance of atmospheric monitoring to understand the dynamics of meteorological exchanges. Continuous measurements from the Atlas Mohammed V Observatory show high seasonal and interannual variability, with an observed increase in CO2 and CH4 concentrations over the last five years. This study also highlights the significant effects of climate change on land degradation, deforestation, and soil erosion. Rising temperatures and changing rainfall patterns exacerbate environmental pressures, disrupting ecosystems and compromising socioeconomic resilience.
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This paper summarizes the application of isotope hydrological tools to infer water sources in different parts of the Souss-Massa region of Morocco. The oxygen-18 (18O) isotopic data show a variation between-7‰ upstream and-4‰ downstream, with intermediate values in the medium part of the plain. The upstream watershed, which is the place of condensation and the beginning of the Atlas Mountain, shows more characteristic 2H and 18O-depleted waters. This finding can be explained by the altitude and the continental effects. On the other hand, 2H and 18O-enriched waters values towards the ocean show an evaporation effect near the condensation source or the irrigation returns, notably in the irrigated perimeters. The rain isotope values indicate a main recharge from the Atlasic Mountain, whereas the contribution of the local rains is negligible in downstream. The 2H-18O relationship displays straight lines with variable slopes on an upstream-downstream movement. The slopes, which are below 8 in certain areas, represent the evaporation during the infiltration either by runoff or by irrigation returns. Besides, the different values of slopes correspond to the variables isotopic values observed at a regional scale within the basin.
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The origin of chloride ions in groundwater from the Chtouka-Massa plain (Morocco) was studied by using chemical and isotopic analyses of water, and petrographic and chemical analyses of rocks. It appears that the schist formation, which forms the basement of the studied aquifer, is the main source of the high Cl− concentrations in groundwater. In these schists, chloride is, for a part, probably contained in biotites, and is released into groundwater through the weathering of these minerals. However, the exceptionally high chloride contents of these schists are difficult to explain if one does not assume that they also contain evaporitic-type minerals. To cite this article: S. Krimissa et al., C. R. Geoscience 336 (2004).
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The objective of our study was to determine the current status of alluvial aquifer in the Souss-Massa basin, where the nitrate pollution of groundwater is being increasing along the last decades. A multi-approach methodology using hydrogeology, nitrate concentrations, irrigation type and oxygen-18 and deuterium data, was carried out to identify the sources of this pollution. According to the spatial distribution of nitrate contents, nitrate pollution occurs mainly in Chtouka-Massa plain. More than 36% of the sampled wells exceed the value of 50 mg/L as NO 3-. Groundwater in Souss plain is less polluted comparing it to Chtouka-Massa; only 7% of wells exceed the permitted level. Agricultural practices in the study sites are the main cause of serious nitrate pollution given the superimposition of high nitrate concentrations with the distribution of irrigated perimeters. High nitrate levels are associated with high δ 18 O values, clearly indicating that significant quantities of evaporated irrigation waters infiltrate along with fertilizer nitrate to groundwater system. Different δ 18 O-NO 3-trends suggest isotopically distinct, non-point source origins which vary spatially and temporally, due to different degrees of evaporation/recharge and amounts of fertilizer applied.
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Heterogeneous shallow Plio-Quaternary formations of the Souss Plain represent the most important aquifer in southern High Atlas Mountains in Morocco. The present work was conducted in the Souss Upstream Basin to identify the chemical characteristics and the origin of groundwater in an aquifer under semi-arid climate. Isotopic and hydrochemical compositions combined with geological and hydrogeological data were used for this purpose. The total dissolved solids vary from 239 to 997 mg l−1, and the following groundwater types are recognized: Ca2+–Mg2+–HCO3−, Ca2+–Mg2+–SO42− and Ca2+–Mg2+–Cl−. The groundwater is saturated and slightly supersaturated with respect to carbonate minerals and undersaturated with respect to evaporite minerals, which means that the groundwater composition is largely controlled by the dissolution of carbonate rocks known in the basin. The isotopic contents of groundwaters ranged from −8‰ to −5.2‰ for δ18O, from −52‰ to −34‰ for δD, and from 0 to 5.5 TU for tritium. The hydrogen (δD) and oxygen (δ18O) isotope signatures reveal a significant infiltration before evaporation takes place, indicating a major recharge directly from fractures in the crystalline and limestone formations of Atlas Mountains (above 800 m a.s.l.) and infiltration of surface water in the alluvial cones at the border of the Atlas basins. The very low tritium values suggest that the groundwater recharge follows a long flow path and a mixing between old and modern water is shown. However, a slight evaporation effect is noted in the southern part of the basin close to the Anti-Atlas Mountains.
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The chemical content of the Souss unconfined groundwater displays spatial variations in conductivity (between 400 and 6,000 S cm-1). The chemical tracers (Cl-, SO42-, Sr2+, Br-), which characterize the different components of the groundwater, allowed the determination of the origin of water salinity. Cl- and SO42-, reaching respectively 2,000 and 1,650 mg L-1, display localized salinity anomalies. Br-/Cl- ratio distinguishes marine-influenced impoverished zones versus the oceanic domain. Thus, salinity anomalies can be attributed: (1) downstream, to a currently existing salt-encroachment (with added waste water) and sedimentary palaeosalinity, (2) in the middle-Souss, to High Atlas evaporites and to irrigation water recycling. Sr2+/Ca2+ ratio (evaporites if >1‰), confirms the evaporitic origin of the anomalies along the right bank of oued Souss. Furthermore, it facilitates the distinction between the different aquifer contributions (Cretaceous, Jurassic and Triassic), and it highlights leakage from deep Turonian limestones in the groundwater recharge system. To the south, recharge is from the Anti Atlas (evaporite-free) waters. Oxygen-18 measurements confirm the groundwater recharge from the High and Anti Atlas as piezometric maps and chemical tracers suggested, plus from leakage from the Turonian and the marine aquifers.
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Heat waves are a major cause of weather-related deaths. With the current concern for global warming it is reasonable to suppose that they may increase in frequency, severity, duration, or areal extent in the future. However, in the absence of an adequate definition of a heat wave, it is impossible to assess either changes in the past or possible consequences for the future. A set of definitions is proposed here, based on the criteria for Heat stress forecasts developed by the National Weather Service (NWS). Watches or warnings are issued when taresholds of daytime high and nighttime low heat index (H 1) values are exceeded for at least two consecutive days. The heat index is a combination of ambient temperature and humidity that approximates the environmental aspect of the thermal regime of a human body, with the NWS thresholds representing a generalized estimate of the onset of physiological stress. These thresholds cannot be applied directly nationwide. In hot and humid regions, physical, social, and cultural adaptations will require that the thresholds be set higher to ensure that only those events perceived as stressful are identified. In other, cooler, areas the NWS criteria may never be reached even though unusually hot events may be perceived as heat waves. Thus, it is likely that a similar number of perceived heat events will occur in all regions, with the thresholds varying regionally. Hourly H 1 for 178 stations in the coterminous United States was analyzed for the 1951-90 period to determine appropriate threshold criteria. Use of the NWS criteria alone indicated that much of the nation had less than three heat waves per decade, and this value was adopted as the baseline against which to establish suitable thresholds. For all areas, a percentile thresholds approach was tested. Using all available data, daytime high and nighttime low thresholds were established separately for each specific percentile. Heat waves were treated as occuring when conditions exceeded both the daytime high and the nighttime low thresholds of the same percentile for two consecutive days. Several thresholds were tested. For much of the South, 1% thresholds produced appropriate values. Consequently, a heat wave was defined as a period of at least 48 h during which neither the overnight low nor the daytime high H 1 falls below the NWS heat stress thresholds (80° and 105°F, respectively), except at stations for which more than 1% of both the annual high and low H 1 observations exceed these thresholds, in which case the 1% values are used as the heat wave thresholds. As an extension, "hot spells" were similarly defined, but for events falling between the 1% values and NWS thresholds, with "warm spells" occuring between the 2% and 1% values. Again, stations for which the 1% or 2% H 1 values exceed the NWS thresholds were given modified definitions. The preliminary investigation of the timing and location of heat waves resulting from these definitions indicated that they correctly identified major epidemiological events. A tentative climatic comparison also suggests that heat waves are becoming less frequent in the southern and more frequent in the midwestern and eastern parts of the nation.
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Two "smart' interpolation procedures are presented and assessed with respect to their ability to estimate annual-average air temperatures at unsampled points in space from available station averages. Smart approaches exmained here improve upon commonly used procedures in that they incorporate spatially high-resolution digital elevation information, an average environmental lapse rate, and/or another higher-resolution longer-term average temperature field. Two other straightforward or commonly used interpolation methods also are presented and evaluated as benchmarks to which the smart interpolators can be compared. Smart approaches are significantly more accurate than either traditional methods or estimates spatially interpolated from a high-resolution climatology alone. A smart interpolation method that makes combined use of a digital elevation model (DEM) and traditional interpolation was nearly 24% more accurate than traditional interpolation by itself. -from Authors