Keywords

1 Introduction

To deal with the increasing global water crisis, desalination plants have become the latest vogue, providing alternative freshwater sources. There were about 14,500 facilities in 2010 and approximately another 240 units under construction in the world but the highest desalination capacity is located in the Middle East. The global number of desalination plants is expected to continue to rise for the foreseeable future [1]. Desalination processes can be undertaken with several technologies. The most common are units based on multistage flash (MSF) distillation, which uses steam, and processes using reverse osmosis (RO), which is a membrane technology driven by electric pumps [2]. MSF desalination technology is mainly used across the Middle East. However, in recent years RO seawater desalination plants have become more popular, because of their sustainability, cost effectiveness, and simplicity, achieved by technological improvement [1].

In spite of desalination technologies development, the costs of desalinated water are still too high for the full use of this resource in irrigated agriculture, with the exception of intensive horticulture for high-value cash crops, such as vegetables and berries (mainly in greenhouses), grown in coastal areas (where safe disposal is easier than in inland areas) [3]. For agricultural uses, RO is the preferred desalination technology because of the cost reductions driven by improvements in membranes in recent years. Many people think that this application is not feasible for irrigation due to the high water costs, but the reality is that it has been used in many countries with success for years such as Spain and some GCC countries providing a significant example of application of desalinated water inirrigation. For example, Spain has more than 300 treatment plants, about 40% of the total number of existing plants and 22.4% of the total desalinated water is used for agriculture. Most of these plants process brackish water (only 10% of the total desalinated water for agriculture originates from seawater) and are located in coastal areas or within 60 km from the sea. In this country, small- and medium-sized brackish-water desalination plants, with a capacity of less than 1,000 m3/day (11.6 l/s), are common because they adapt better to individual farmer requirements and to the existing hydraulic structures [4].

Souss-Massa region in the south of Morocco is considered the most productive in terms of horticultural products especially destined for export. The part of the region in exportation of fruit and vegetable is about 90% at national level. The greenhouse cropping system is the most common with more than 15,000 ha of crops grown under greenhouses. However, this region suffers from a serious problem of water scarcity, where the annual rainfall does not exceed 200 mm, and the water deficit is more than 280 Mm3. Furthermore agriculture, in this region, consumes about 90% of the water resources. Overpumping of groundwater is among the practices aggravating the situation by lowering the water table and consequently increasing pumping costs and groundwater salinization due to seawater intrusion, especially in the coastal areas. Using desalination of seawater for irrigation of cash crops as tomato and berries and other vegetables crops could be a judicious solution to maintain a sustainable horticultural production and water saving [5].

This paper provides a review about water resources situation and management in Chtouka region as well as a technical description of the public–private partnership (PPP) desalination project destined to irrigation focusing on its impacts, benefits, and institutional aspects.

2 Current Situation of Water Resources in Souss-Massa Basin

The Souss-Massa river basin, which is bounded on the north by the High Atlas mountains and on the south and east by the Anti-Atlas mountains, covers approximately 27,000 km2. The Souss-Massa region is characterized by an arid climate with low precipitations (<200 mm/year). The annual rainfall is very variable; precipitations of the humid year sometimes reach 3 times of the average year and 15 times of the dry year. Surface water is collected and stored behind seven dams that have a combined total capacity of approximately 800 Mm3 [6]. The total water use in the basin is approximately 1,034 Mm3/year, 36% from surface water and 64% from aquifers, 95% of this quantity is used mainly in agriculture, and 5% as drinking and industrial water [7]. Overall, demand for water exceeds the sustainable supply, with the deficit being made up by groundwater overexploitation. Overpumping of the alluvial aquifer exceeds an average of 284 Mm3/year in Souss aquifer and 58 Mm3/year in Chtouka aquifer (Table 1), which has resulted in water level declines ranging from 0.5 to 2.5 m per year during the past three decades. According to ABHSMD [8], the piezometric level analysis in the Souss-Massa aquifers between 1968 and 2003 shows a reduction in water table level of about 15 m in the Souss upstream, more than 30 m in the middle Souss, and 20 m in the Souss downstream. While in the Chtouka aquifer, the piezometric level was reduced by more than 20 m.

Table 1 Water balance in Souss and Chtouka aquifer
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The deterioration of water quality is observed in many zones marked by an increase of TDS and nitrate contents. The interannual monitoring shows that Souss downstream groundwater present a low quality while in medium and Souss upstream, the quality is generally good as well as in Chtouka where the water quality is mainly suitable. Recently, several hydrochemical and isotopic studies were carried out in order to assess the recharge and the quality of groundwater, to define the sources of groundwater salinization, and to find out the impacts of agricultural activities as irrigation and fertilization on groundwater quality [9–12]. Therefore, the overall quality of groundwater in the Souss-Massa aquifers shows a deterioration from east to west in Souss plain and from north to south in Chtouka plain. According to Tagma et al. [12], the Souss and Chtouka aquifer are the most contaminated aquifers in the regions, 36% of wells exceed the regulatory threshold of drinking water which is equal to 50 mg/l of nitrates. In the Souss region, it is relatively less affected; 7% of wells presented nitrate concentration more than 50 mg/l with an average of 22 mg/l. The irrigated areas seem to be the most affected by nitrate pollution. The overall degradation of Souss and Chtouka aquifer is mainly due to geological origin (evaporates) and anthropogenic activities (fertilizers and wastewater).

3 Economic Importance of Agriculture in Souss-Massa Region

Agriculture constitutes an economic pillar for Souss-Massa region where it contributes by 13% of the regional GDP (Gross Domestic Product). According to the Ministry of Agriculture and Fishery [13], the production of agricultural sector should know an increasing from 11,838 Million DH in 2010 to 17,669 Million DH in 2020. The created working days increased from 30,804 working days in 2010 to 36,845 working days in the horizon of 2020. Table 2 shows the agricultural production and the national part of the Souss-Massa region. Data indicate that the region produces 77% of vegetables and 40% of citrus fruits. Those crops require very high water requirements. However the available water quantity could not satisfy the increased development in the agricultural sector. Thus the need for new water resources becomes a priority of all agricultural producers and users as well as water authorities.

Table 2 Cereals and horticultural production (×1000 T) in the Souss-Massa region [13]
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4 Water Resources Management Scenarios in Souss-Massa Region

According to the current situation of water resources management in Souss-Massa region, we can distinguish between 2 management scenarios which likely to be occurred in the future. The catastrophe scenario which is the pessimistic scenario under which the current management of water resources and their misuse will continue without any measures of preservation. The safeguarding scenario under which many water preservation strategies and measures will be adopted by the managers and water users [14].

4.1 Catastrophe Scenario

This scenario is characterized by an overexploitation of water resources without any measures to be taken by water users and decision makers. Prediction results of the groundwater level in Chtouka aquifer are presented in Fig. 1:

Fig. 1
figure 1

Piezometric level evolution in the Chtouka aquifer

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Figure 1 shows clearly that during the last decades groundwater level decreased by more than 30 m. This reduction will result in a second time a salt accumulation in the soil and groundwater quality degradation due to misuse of fertilizers and seawater intrusion. Consequently this increase in salinity may lead to the installation of desalination individual units in larger farms. In 2010, some farmers have already installed this technology. However, this advanced technique would only be a step in the tragedy since brines issued from desalination will be discharged directly into the aquifer which lead certainly to groundwater salinity increase.

Losses associated with this scenario can be summarized as follows:

  • Capital losses on all greenhouses, borehole, wells, and associated packaging houses. It is clear that the value of a borehole or well after saline intrusion is zero due to the fact that these installations cannot be moved

  • Loss in value of the total production using groundwater from Chtouka aquifer

  • Job losses for labor used in production and packaging

  • Job losses in inputs and services suppliers related to agricultural sector

The economic impact of the catastrophe scenario was estimated using a model based on representative farms samples associated with a packaging station. This representative model defines the added value per hectare, the number of agricultural jobs, packaging, and the capital invested per hectare. Table 3 summarizes the results obtained according to the nature of the losses:

Table 3 Total losses of the catastrophe scenario in the horizon of 2035 [14]
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4.2 Safeguarding Scenario

Water managers in the Souss-Massa region propose a preservation scenario to limit the imbalances in water resources by an active policy of mobilizing additional resources. This scenario is based on a political offer engaging all water users and stakeholders and aims to increase water offer to cope with existing water deficit. Several preservation measures are adopted in this scenario, some of them have already taken place and others are planned in the future:

4.2.1 Water Supply Management Strategies

  • Construction of dams planned in the PDAIRE (Master Plan of Integrated Development of Water Resources)

  • Rainwater harvesting

  • Seawater desalination

  • Wastewater reuse

  • Artificial recharge

  • Water transfer from north basins

  • Interconnection of hydraulic systems

  • Saline water demineralization

  • Use of saline water

4.2.2 Water Demand Management Strategies

  • Adaptation of less water consumer crops

  • Infrastructure rehabilitation

  • Cropping adaptation technique to save water (hydroponics)

  • Conversion to drip irrigation (facilitation of procedures for water users associations and small farmers, extension services): already 30,000 ha have been converted

  • Control of water withdrawal and pumping

4.2.3 Transversal Actions

  • Revision of water pricing

  • Water governance (groundwater contract, implementation, and strengthening of water users associations)

  • Public–private partnership

  • Encourage scientific research

  • Capacity building

  • Improve groundwater monitoring

  • Improve hydrological monitoring

  • Improve water withdrawal monitoring (remote sensing)

  • Monitoring and evaluation of projects

  • Encourage transnational cooperation

  • Encourage the data exchange between stakeholders

In the horizon of 2030, water supply will be increased by almost 20%, from 901 to 1,171 Mm3/year if the safeguarding scenario has occurred (Fig. 2). This increase in supply should lead to a return to the groundwater balance and satisfaction of growing demand. The safeguarding scenario balance even exceeds the water demand and allows a surplus of 100 Mm3/year.

Fig. 2
figure 2

Evolution of water balance under the safeguarding scenario towards 2030 [14]

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5 Seawater Desalination Public–Private Partnership Project for Irrigation

The Ministry of Agriculture and Fishery was engaged in irrigation project using desalinated seawater in the Chtouka zone in the Souss-Massa region. This project has a particular importance in Morocco as it is implemented within the frame of the National Green Plan as a PPP (Public–Private Partnership) project. The project will support the agricultural development in the Souss-Massa region as it is the first region in terms of production and export of agricultural products with high added value. This project will respond to vegetables and fruits producers needs in the Chtouka zone.

5.1 Willingness to Pay for Desalinated Water: Farmers Survey

The AgrotechFootnote 1 association has carried out in collaboration with the ORMVASMFootnote 2 (agricultural development office) surveys covering most of greenhouse producers in the Chtouka zone. The objectives of this survey are:

  • To identify the area equipped by greenhouses determining the spatial distribution of greenhouses

  • To determine the total water volume used by the farmers and the potential desalinated water volume that will be required

  • To know the farmers opinion about the use of desalinated water for irrigation and their interest to be part of the project

The survey covered 847 greenhouses farms with a total area of 12,770 ha. The obtained results are presented in Tables 4, 5, and 6 [15].

Table 4 Characteristics of the surveyed area
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Table 5 Survey results in terms of area and volume
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Table 6 Survey results in terms of farm number and volume
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5.2 Description of the Seawater Desalination Project

The technical characteristics of the project are:

  • The concerned area: 9,000 ha (at the beginning of the project run) and 13,600 ha (in the horizon of 2035)

  • Required desalinated water: 55 Mm3/year (the aquifer water pumping should not exceed 25 Mm3/year within the limits of renewable groundwater)

  • 2,500 beneficiaries

  • Water price: 6 DH/m3, 0.61 $

  • Desalination plant

    • Location: coastal site in the National Park of Souss-Massa (between Tifnit and Douira)

    • Capacity: 111,000 m3/day in the beginning of the project run and 166,500 m3/day in the horizon of 2035

    • Desalination technique: reverse osmosis with double pass

    • Modular and advanced plant to follow the progressive development of the project

    • Electrical powers: 34 MW

  • Infrastructures of pumping and distribution of desalinated water for irrigation

    • Pumping station to pump the desalinated water into a regulation and control basin

    • Pumping from the regulation basin to mean distribution network

    • Mean distribution network of 290 km

    • Pressuring station

    • 1360 hydrants

The project will be built within the frame of public service delegation to a private operator (PPP) who will be charged to build, design, and manage all infrastructures related to the seawater desalination and irrigation especially after the success of the El Guerdane irrigation PPP project.Footnote 3 All the concerned parts by the delegated management convention (state, regional consul, banks, and users) will provide a financial contribution in the initial investment. The users contribution will be related to membership fees (Fig. 3). Users will pay membership fees to the operator in charge to use the desalinated water for irrigation [16].

Fig. 3
figure 3

Institutional framework of the project

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5.3 Impacts of the Seawater Desalination Project

The project will have a positive impact in the environment as it will contribute significantly in the reduction of the aquifer overexploitation and consequently the project will achieve an equilibrium in terms of groundwater balance as well as sustainable use of the aquifer in Chtouka zone and preservation of groundwater dependent ecosystems (forests, wild parks, etc.). Through this project the region will avoid a loss of nearly 9 billion DH as added value and 3 billion DH as capital in the horizon of 2035. The project will allow to increase the agricultural added value by 21.9% and preserve more than 2,830 permanent jobs and even reach over 4,275. Consequently the project will preserve a great horticultural expertize and export markets (Fig. 4).

Fig. 4
figure 4

Projection of water balance in Chtouka region, note the impact of desalination project in decreasing the aquifer output and increasing water supply

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The implementation site has been chosen to allow a zero impact especially on the bald ibis birds protected under the national park of Souss-Massa where the project will be installed. The infrastructures have been designed to control the brines disposal through the use of modern technology. A marine cartography and mapping will be performed in order to minimize the impacts and risks as maximum as possible [5]. A major environmental problem of water desalination is the production of a flow of brine containing the salts removed from the intake water and that needs to be disposed. In addition, this brine may be polluted. This brine represents a significant fraction of the intake water flow. Seawater desalination typically yields a brine flow of 50–65% of the intake water flow, with about twice the initial concentration [17]. As the project will be implemented in coastal area, the brine will be safely disposed in the Atlantic Ocean without any significant impacts on the coastal ecosystems.

6 Conclusion

There are a number of benefits for desalinated water use in the agricultural activity in Chtouka region. The most obvious one is that the technology produces an additional water resource to cope with increasing water deficit, but additionally, there is an increase in crop productivity and quality. However, costs are a major limitation and less expensive options are likely to be more attractive for agriculture. The desalination project in Chtouka aims to increase the water availability for greenhouse producers, to maintain their socioeconomic activities and to contribute to regional and national economy. Using desalination water for irrigation is much suitable for high cash crops destined to export as tomato, berries, green beans, salads, etc., where the cost of water can be compensated by the high selling price. Situation without desalination project is seen to be worst in the future especially numbers about economic added values losses are indicating that Souss-Massa region which is depending widely on groundwater will be subjected to catastrophic scenario.