Estimating the Economic Cost of Land Degradation and Desertification in Morocco

Abstract

Desertification affects over 90% of Moroccan territory, leading to soil degradation that reduces agricultural productivity, diminishes biodiversity, and alters environmental functions. This study estimates the total economic cost of desertification in Morocco using a zonal approach based on regional sensitivity. The methodology includes two stages: quantifying productivity losses from water and wind erosion, salinization, overgrazing, silting of dams, carbon storage loss, and land-use changes; and monetizing impacts using methods such as productivity change, replacement cost, and the social cost of carbon. The total cost is estimated at USD 2.1 billion per year, with 78.02% from agricultural and grazing land productivity losses, 2.95% from dam silting, 18.47% from carbon storage loss, and 0.56% from land-use changes. These findings underscore the urgency of public policies, including land use planning, sustainable agriculture, irrigation modernization, and community engagement. Drawing on successful initiatives in the MENA region and globally, Morocco can mitigate desertification’s impacts and foster sustainable development.

1. Introduction

Desertification, characterized by the degradation of land productivity, is a pressing environmental and developmental challenge exacerbated by anthropogenic activities, climate variability, and biodiversity changes [1,2,3]. This phenomenon affects over 40% of the global population, with more than 90% residing in developing countries, particularly in arid, semi-arid, and dry sub-humid regions [4]. Drylands, occupying 40% of the Earth’s terrestrial surface, are the most vulnerable, with Africa accounting for 37% of global dryland areas, followed by Asia (33%) and Australia (14%) [5].

In Morocco, desertification is a critical issue, impacting over 90% of the country’s territory, particularly in arid and semi-arid zones. This process is driven by fragile soils, climate conditions, and unsustainable exploitation of natural resources by rural populations [6,7]. To combat desertification, Morocco adopted a National Action Program to Combat Desertification (PANLCD) in 2001, emphasizing territorial integration, participatory approaches, and synergy between sectoral programs [8,9,10].

Land degradation imposes significant global economic costs, estimated at over USD 10 trillion annually, due to productivity losses, biodiversity decline, and water pollution [11]. While sustainable management projects, such as Mali’s restoration initiative, have demonstrated high returns on investment (e.g., USD 12 for every USD invested), the economic burden remains disproportionately high in developing countries, where rural livelihoods are heavily dependent on natural resources. In Morocco, the economic cost of environmental degradation was estimated at USD 3.41 billion (3.52% of GDP) in 2014 [12].

Despite extensive research on global land degradation, few studies isolate desertification as a distinct phenomenon or address the economic costs associated with its impacts. Existing studies often overlook regional variations in these costs, particularly in heterogeneous landscapes like Morocco. This study seeks to fill this gap by answering the question: “How are the economic costs of desertification impacts distributed across Morocco’s homogeneous zones, and what are the variations in these costs?”

To address this question, the study aims to:

• Assess land degradation and its economic impacts across Morocco’s homogeneous zones.
• Quantify productivity losses resulting from water and wind erosion, salinization, overgrazing, and changes in land use.
• Develop actionable recommendations for sustainable land management tailored to the specific characteristics of each homogeneous zone.

By leveraging spatial analysis tools such as InVEST 3.10.2 software and economic evaluation methodologies—including productivity change and replacement cost—this research highlights the importance of incorporating desertification costs into decision-making. It also provides a framework for tailoring strategies to mitigate desertification and promote sustainable development in Morocco’s diverse regions.

2. Literature Review

2.1. Global Perspectives on Desertification and Degradation

Land degradation and desertification have become critical global challenges, threatening ecosystems, economies, and livelihoods. The increasing reliance on satellite imagery and geospatial analysis has enhanced our understanding of these issues on a regional and global scale. Studies such as those by [13,14] have underscored the alarming rates of soil erosion under current land management practices and projected their worsening under climate change scenarios. These studies highlight the urgent need for targeted mitigation and adaptation strategies. Additionally, the authors of [15] provided a framework for linking land degradation to economic costs, emphasizing the global implications of failing to address desertification.

Other studies have shed light on regional disparities in desertification drivers and impacts. For example, ref. [16] demonstrated how varying socio-economic conditions influence land degradation trends across the MENA region. In sub-Saharan Africa, ref. [15] highlighted the role of poverty and weak governance in accelerating land degradation while simultaneously showcasing successful interventions through community-driven restoration projects. These global and regional perspectives underscore the complexity of desertification and the need for region-specific solutions.

2.2. Advances in Assessing Land Degradation

Technological advancements have played a pivotal role in advancing the methodologies used to assess land degradation. For instance, the integration of remote sensing data with field observations, as demonstrated by [15], has improved the accuracy of identifying degraded lands. Similarly, ref. [17] explored how hydrological modeling combined with socio-economic data can provide deeper insights into the cascading effects of degradation on water resources and agricultural productivity. Such interdisciplinary approaches have set a new benchmark in understanding the multifaceted nature of land degradation.

The use of spatially explicit models has also become increasingly prominent. The Universal Soil Loss Equation (USLE) remains a cornerstone for soil erosion assessments, but its integration with advanced tools like the InVEST Sediment Delivery Ratio (SDR) model has allowed for greater precision in quantifying erosion and its economic impacts [18,19]. Meanwhile, the application of machine learning techniques in land use classification, as seen in studies by [20], has improved the reliability of degradation assessments, particularly in heterogeneous landscapes.

Beyond technical tools, frameworks for understanding the socio-economic dimensions of desertification have gained traction. Ref. [21] emphasized the need to integrate socio-economic variables into desertification studies, arguing that land degradation cannot be fully understood without considering human activities, institutional weaknesses, and governance structures. Similarly, the role of community participation in combating desertification has been highlighted in studies like those of [22], who demonstrated the effectiveness of participatory approaches in reversing degradation trends in vulnerable regions.

2.3. Economic Impacts and Policy Implications

The economic consequences of land degradation are profound, with far-reaching impacts on national economies and local livelihoods. Ref. [12] estimated that land degradation costs some countries as much as 9% of their GDP annually. In the MENA region, ref. [12] found that Morocco’s economic losses due to environmental degradation amounted to 3.52% of GDP, highlighting the urgency of addressing these issues. Studies have emphasized the need for robust policy frameworks that integrate land restoration with socio-economic development. For instance, ref. [15] suggested that incentivizing sustainable land management practices through subsidies and community programs can yield significant economic and environmental benefits.

2.4. Relevance to the Case Study

This study builds upon the methodologies discussed, applying them to Morocco’s unique context. Unlike global studies that provide generalized findings, this research employs a zonal approach to assess economic costs across Morocco’s homogeneous zones. By integrating spatial tools like InVEST and incorporating recent economic valuation techniques, this study bridges critical gaps identified in the prior literature, such as those highlighted [12]. Furthermore, it contributes to the growing body of knowledge by demonstrating how localized assessments can inform national and regional policy frameworks.

2.5. Analytical Framework for the Case Study

To ensure a robust analysis, this study adopts an interdisciplinary framework that integrates biophysical and economic methodologies. Key components include:

• Spatial analysis tools: Advanced tools like the InVEST SDR model and carbon storage models were employed to quantify erosion and ecosystem service losses. These tools provide high-resolution insights into degradation patterns, enabling targeted interventions.
• Economic valuation: The economic impacts of degradation were monetized using established methods, including replacement costs for dam siltation and social costs of carbon for ecosystem losses. This approach ensures alignment with global best practices while tailoring the results to Morocco’s context.
• Zonal approach: By segmenting Morocco into homogeneous zones based on climatic, geological, and land-use characteristics, this study captures the spatial variability of degradation impacts. This approach ensures that recommendations are context-specific and actionable.

3. Materials and Methods

3.1. Study Area

3.1.1. Relief and Climate

Morocco’s relief (Figure 1a) has been spatialized on the basis of USGS Earth Explorer data at 30 m resolution and is highly diversified, influencing both climate and vegetation. On the one hand, there are the mountain ranges with their high peaks, such as the mountain of Toubkal at 4167 m, which is the highest point in the Anti-Atlas, Middle Atlas, and High Atlas, as well as the Rif mountains. In addition, there are the fertile Atlantic coastal plains and the arid plateaus to the east, and finally, the south and southeast regions of the country (the Sahara) are dominated by expanses of desert and Saharan dunes.

With regard to rainfall distribution, we used [23] standardized rainfall index over 40 years (1981–2020). After studying this map (Figure 1b), we can see that the Rif mountain range in the north is the country’s wettest region, with annual rainfall totals in excess of 1000 mm, records annual rainfall of less than 400 mm, with values decreasing towards the south and west, particularly in the area framed by the Atlas Mountains, with stations recording values ranging from 600 mm in the north to 200 mm in the south. The south and southeast, which are the pre-desert and Saharan domains, are characterized by extreme drought, with annual accumulations of less than 100 mm.

3.1.2. Soil and Vegetation

The land cover of Morocco 2020 (Figure 1c) with a resolution of 10m was drawn up based on the [24] SENTINEL-2 Land Cover product, which was created using SENTINEL-2 satellite imagery from the European Space Agency (ESA). The Impact Observatory is the classification model used to create this product, and it identified 10 classes of the earth’s surface, including vegetation, bare surfaces, crops, and urban areas.

Morocco’s soils (Figure 1d) are the fruit of varied and sometimes complex natural processes, giving rise to a great diversity of soils. According to [25], Morocco has sandy soils rich in iron oxides, clay soils near the coast, and brown soils under forests, which are highly suitable for agriculture. In limestone areas, the slope and disappearance of vegetation accelerate soil degradation. There are also rough mineral soils on rocky formations and eroded soils on marl soils, as well as shallow soils on steep slopes, which are highly subject to erosion.

Figure 1. (a). Relief map of Morocco. Source: [26]. (b). Map of mean annual precipitation in Morocco (1981−2020). Source CHIRPS data: [23]. (c). Impact Observatory land-use map of Morocco 2020. Source: adapted from [24]. (d). Typical soil map of Morocco. Source: [25].

Figure 1. (a). Relief map of Morocco. Source: [26]. (b). Map of mean annual precipitation in Morocco (1981−2020). Source CHIRPS data: [23]. (c). Impact Observatory land-use map of Morocco 2020. Source: adapted from [24]. (d). Typical soil map of Morocco. Source: [25].

3.2. Methodology

In order to study the phenomenon of land degradation and desertification in Morocco, we worked on eight homogeneous zones (Figure 2) identified and delimited within the framework of the PANLCD 2013 with regard to sensitivity to desertification. In fact, the delimitation of these zones was based on 3 main criteria according to [9], which are relief, climate, and soil capital.

To estimate the total economic cost of desertification in Morocco in 2020, we proceeded to monetize the impacts of desertification. The methodological approach adopted in our study does not cover all the cases likely to occur in reality but focuses on the most frequently encountered and most important cases. We have used a zonal approach to desertification sensitivity to calculate the costs of the following types of degradation: degradation of agricultural land by water and wind erosion and salinization, followed by overgrazing of rangelands, silting of dams, loss of carbon storage, and changes in land use.

To do this, our methodology is divided into 2 main stages: firstly, we quantified the various impacts of degradation based on InVEST, the PANLCD 2013 report, and secondly, we monetized these impacts using the various methods for assessing the economic cost of degradation, the totals of which are the total economic cost of desertification in Morocco in 2020.

3.2.1. Quantifying the Impacts of Desertification

A. Degradation of agricultural land

A-1 erosion

In order to assess the extent of water erosion-related land degradation in Morocco, we used the Sediment Delivery Ratio (SDR) model of the InVEST tool, which uses the universal soil loss equation of [27]: USLE = R × K × LS × C × P to estimate the potential soil loss for each pixel within the country.

The inputs to the SDR model are as follows:

• Digital terrain model raster (Figure 1a);
• Raster of the erosivity factor (R) (See Supplementary Materials Figure S1) calculated on the basis of the global rainfall erosivity map [28];
• Raster of the erodibility factor (k) (See Supplementary Materials Figure S2) determined using the harmonized soil database [13] and the erodibility factor estimation table K [29];
• Land use raster (Figure 1c);
• Biophysical table (

  Table 1. Biophysical table of sediment delivery ratio (SDR) model.

  Description	Lucode	Usle_c	Usle_p	Data Source
  Water	1	0.04	1	[18]
  Forest	2	0.003	1	[18]
  Pastures	3	0.15	0.9178	[19]
  Wetlands	4	0.03	1	[18]
  Cultivated Land	5	0.19	1	[18]
  Shrub vegetation	6	0.05	0.9178	[19]
  Built-up areas	7	0.1	1	[18]
  Bare Soil	8	1	1	[18]

  ) with two factors (—Usle_c: cover management factor—Usle_p: supporting practices factor).

After running the SDR model, we obtained the total amount of potential soil loss due to water erosion in Morocco, then mapped this information by water erosive state, which according to [30] are grouped into 4 states: very low (<5 t/ha/yr), low (5–10 t/ha/yr), medium (10–20 t/ha/yr), and high (≥20 t/ha/yr). As the high level of degradation was irrecoverable, it was not included in the analysis. This map of erosive water conditions was then superimposed on the land use map to determine the surface area of agricultural land affected by light (very low, low) and moderate erosion.

A-2 Wind erosion

To measure the extent of land degradation linked to wind erosion, we used the map (Figure 3) drawn up as part of PANLCD 2013. Studying this map enabled us to calculate the surface area affected by each erosive condition, which are 35.23 million hectares for very low erosion, and 3.37, 24.17, and 7.24 million hectares of affected surface area for low, medium, and high erosion, respectively.

A-3 Salinization

In order to quantify salinization-related degradation, we used the percentage of soil area degraded by salinization, as calculated within the framework of the PANLCD and listed in

Table 2. Percentage of agricultural land area affected by salinization.

Homogeneous Zone	% Area of Agricultural Land Affected by Salinization
1	1
2	1
3	5
4	1
5	1
6	1
7	1
8	1

Source: [9].

. We then calculated the area of soil affected by salinization for each homogeneous zone.

B. Overgrazing of rangelands

To quantify the degradation of rangelands, a two-step method was used.

Firstly, we calculated the overall forage production of natural rangelands (forest, alfa grass cover, and productive rangelands) for each homogeneous zone. Based on the areas drawn from the land use map (Figure 3) and specific data from [31,32], the estimate of productive rangelands was set at 12.5 forage units/ha. The needs of livestock satisfied by stabling, representing 40% of their total consumption, were taken into account [6].

The results were calculated from data provided by the HCP in several reports [32,33,34,35] in Livestock Units (LU) according to the ratios of [6], and forage requirements in forage units per LU were set at 1200 FU/ha. Overconsumption was finally calculated by subtracting local production from the estimated offtake for each zone.

C. Siltation of dams

To quantify ex situ land degradation resulting in dam silting, we initially calculated the amount of sediment exported (in tons per year) by each major Moroccan watershed, using the InVEST (SDR) model and the same parameters as those employed to quantify water erosion (in situ), in addition to shapefiles representing Moroccan watersheds (Figure 4) and then identified the main dams located downstream of each watershed. To quantify dam siltation by homogeneous zone, the watershed map was superimposed on the homogeneous zone map.

D. Loss of carbon storage

In order to quantify the carbon storage lost annually, we used InVEST’s Carbon Storage and Sequestration model, applied between 2000 and 2020. We then calculated the difference in the quantity of carbon between these two dates to determine the quantity of degraded carbon storage in Morocco, and finally to identify its annual loss in Morocco. To do this, we need two inputs: the land cover rasters for the years 2000 and 2020 (See Supplementary Materials Figures S3 and S4), which will be drawn up on the basis of the CAS EARTH [37] product at 30m resolution, using pixel-based image classification and object-based image classification, and offering 10 classes, 8 of which are suitable for Morocco, namely crop, forest, grassland, shrub vegetation, wetland, water body, urban area, and bare soil. We also use a biophysical table (

Table 3. Biophysical table of carbon storage and sequestration.

LULC_Desc	Lucode	C_above	C_below	C_soil	C_dead	Data Source
Cultivated Land	1	44.43	29.3	10.45	0	[20]
Forest	2	132.4	26.14	15.67	0	[20]
Pastures	3	31.2	1.1	18.67	0	[20]
Shrub vegetation	4	10	3	25	0	[19]
Wetlands	5	82	1.3	20	0	[18]
Water bodies	6	0	0	0	0	[18]
Built-up areas	7	3	0.6	13.5	0	[20]
Bare Soil	8	3.5	0.35	16.5	0	[18]

) comprising above-ground biomass carbon density, below-ground biomass, soil carbon, and dead matter carbon.

E. Land use trends

In order to understand the evolution of land use, we used the MCD12Q1.061 MODIS product, which offers 500m resolution with an IGBP classification of 17 classes according to [38], of which only 14 are available in Morocco. Our study was based on multi-date mapping between 2001 and 2020, with change analysis carried out using the Google Earth Engine, which enabled us to obtain the change matrix for transitions between the main land uses, which we will reduce to 7 classes (

Table 4. Classes used to assess land use evolution 2001–2020.

Integration of Classes to Assess Evolution Between 2001 and 2020	Classes MCD12Q1.061
Bare soil or sparse vegetation	Bare soil or sparse vegetation
Cultivated land	A mosaic of cultivated land and natural vegetation
	Cultivated land
Forests	Deciduous forests
	Evergreen deciduous forests
	Mixed forests
	Evergreen forests
Pastures	Pastures
Shrub vegetation	Dense shrublands
	Open shrublands
	Savannahs
	Wooded savannahs
Built-up areas	Urbanized and built-up areas
Wetlands	Wetlands

). In order to attenuate the annual variations recorded due to climatic conditions, notably precipitation, we calculated a five-year moving average of the changes over a 16-year period from 2005 to 2020. Based on the moving averages, we calculated the average annual change for each land use class.

3.2.2. Estimating the Economic Cost of Degradation

A. Degradation of agricultural land

A-1 Erosion

The economic cost of agricultural land erosion due to water and wind erosion in 2020 was estimated on the basis of the loss in value of agricultural production caused by a fall in productivity. For each homogeneous zone, we used four cropping systems: cereal, legume, sugar, and oilseed, based on [32] data by province. We then calculated a weighted average of prices in USD per quintal: 27.83 for cereals, 89.36 for pulses, 72.66 for oilseeds, and 13.38 for sugars to estimate cereal productivity in each homogeneous zone.

In short, the economic cost of lost productivity is calculated by multiplying lost agricultural production (PAP) by the price of cereals in 2020. This estimate was made for each homogeneous zone using the following formula: PAP (homogeneous zone) = lost agricultural productivity × area of land affected by different erosive conditions

A-2 Salinization

To calculate the cost of salinization-induced land degradation, we multiplied the affected land area for each homogeneous zone by 390.5 USD/ha, which is the economic cost induced by losses in agricultural productivity due to salinization according to [12]

B. Overgrazing of rangelands

The cost associated with rangeland degradation is equivalent to the quantity of forage units over-consumed, multiplied by the unit price of a forage unit. Each forage unit represents one kilogram of barley. According to [32], the unit price of a kilogram of barley is between USD 0.26 and 0.83.

C. Siltation of dams

To calculate the cost of land degradation ex situ, we first transformed the quantity of sediment exported from the t into m³, knowing that the weight by volume of dam silt is 1.8 t/m³ [39], then used the replacement cost method. This approach was supported by reference to the cost of developing water resources, assessed on the basis of the cost of mobilizing water from another dam intended to replace the lost storage capacity, which consisted of multiplying this quantity by the average cost of developing the mobilized water, varying between 0.21 and 0.63 USD/m³ according to data from [40].

D. Loss of carbon storage

In order to estimate the economic cost of the loss of carbon storage, our analysis is based on the social valuation of a ton of sequestered carbon, representing the social damage avoided by preventing the release of CO₂. According to [12], the social price of carbon ranges from USD 40 to 80. To monetize the quantity of degraded carbon obtained by the InVEST model, we multiply this quantity by the extreme values of this range, then average the two.

E. Land use trends

To estimate the cost of the average annual change in land use on the total economic value (

Table 5. Total economic value of ecosystems (TEV).

Land Use	VET (USD/Year)	Data Source
Forest	103	[12]
Wetlands	9778	[41]
Cultivated land	482	*
Pastures	132	[12]

* Value estimated by the authors based on available agricultural productivity data for Morocco (2022).

), 4 classes will be retained for reasons of significant importance.

4. Results

4.1. Degradation of Agricultural Land

4.1.1. Water Erosion

Running the SDR model of the InVEST tool generated a map of land degradation (Figure 5) resulting from water erosion in Morocco. The classification of the latter by erosive state shows us that Morocco is affected by light erosion (very low and low) on sixty percent of its surface, nine percent is affected by moderate erosion, and one-third is affected by strong erosion.

On the one hand, the surface area of agricultural land affected by the various erosive conditions was obtained by superimposing the land use map and the map of erosive water conditions in Morocco. Extracting the results by homogeneous zone enabled us to calculate the surface area of agricultural land degraded by water erosion by homogeneous zone.

In addition, the calculation of lost productivity in Q/ha (quintal per hectare) per homogeneous zone according to light and medium erosive conditions and its product by the agricultural areas (ha) affected by these two conditions provided us with the average production (Q) lost per homogeneous zone. Lastly, we estimated the cost of lost cropland production caused by water erosion (

Table 6. Annual costs of loss of cropland production caused by water erosion (×1 million USD).

Homogeneous Zone	Average Productivity (Q/ha)	Lost Production (1000 Q/Year) Due to Light and Medium Erosion	Cost (×1 Million USD /Year)
1	4.4	4	0.1
2	20.1	71.6	2
3	6.9	265.5	7.4
4	38.4	3255.8	91.2
5	9.9	1978.4	55.4
6	23	767.54	21.5
7	27.2	3011.2	84.4
8	11	32.3	0.9
Total		9386.6	263.1

), which results in an annual loss of USD 263.1 million.

4.1.2. Wind Erosion

Following the same approach adopted to monetize the impact of water erosion, and based on the wind erosion conditions (Figure 3), we calculated the cost of lost cropland production caused by wind erosion, which results in an annual loss of USD 317.6 million (

Table 7. Annual costs of loss of cropland production caused by wind erosion (×1 million USD).

Homogeneous Zone	Average Productivity (Q/ha)	Lost Production (1000 Q/year) Due to Light and Medium Erosion	Cost (×1 Million USD /year)
1	4.4	5.4	0.15
2	20.1	61.2	1.7
3	6.9	239.8	6.7
4	38.4	2981.9	83.6
5	9.9	1934.3	54.2
6	23	850.1	23.8
7	27.2	4988.3	139.8
8	11	269.2	7.5
Total		11,330.67	317.6

).

4.1.3. Salinization

The cost of agricultural land degradation associated with salinization in Morocco is USD 25.03 million (

Table 8. Annual costs of loss of cropland production due to salinization (×1 million USD).

Homogeneous Zone	Affected Farmland (ha)	Economic Cost (USD Million)
1	119	0.04
2	603.2	0.23
3	17,284	6.75
4	7764.2	3.03
5	13,451	5.25
6	3760.5	1.47
7	18,550	7.25
8	2568.7	1.00
Total	64,100.6	25.03

).

4.2. Degradation of Rangelands Through Overgrazing

Total forage production from forests and productive rangelands was calculated by homogeneous zone, with Homogeneous Zone 4 standing out as the most productive, closely followed by Homogeneous Zone 6, while Homogeneous Zone 5 had the lowest production. Calculation of forage harvesting by livestock by homogeneous zone revealed that Homogeneous Zone 7 had the greatest pressure from livestock, followed by Homogeneous Zone 5, while Homogeneous Zone 8 had the lowest annual forage harvesting. The annual cost of pasture degradation due to overgrazing is estimated at USD 1.03 billion (

Table 9. Annual costs of pasture degradation due to overgrazing (×1 million USD).

Homogeneous Zone	Annual Production (106 UF)	Annual Withdrawal (106 UF)	Annual Overconsumption (106 UF)	Economic Cost (Million USD)
1	177.8	310.8	132.4	37.5
2	143.8	218.2	74.4	21
3	332.6	744	411.3	116.6
4	486.2	1012.4	526.1	149.1
5	27.2	1126.5	1099.2	311.6
6	373.7	889.2	515.5	146.1
7	104	1377.5	1273.5	361
8	62.9	215.2	152.3	43.1
Total	1708.5	5893.8	4184.9	1037.1

).

In order to spatialize the intensity of the pastoral load (Figure 6), we calculated the index of pastoral pressure by homogeneous zone, which is the ratio between the actual load and the equilibrium load. Given that these homogeneous zones are very extensive, the calculation of these indices was reduced to the provincial level of the country, and analysis of the results shows that Homogeneous Zone 5 suffers the greatest pressure, followed by Homogeneous Zone 7, while Homogeneous Zone 2 endures the least intensity.

4.3. Dam Silting

The economic cost induced by dam silting is an annual value of 61.6 million USD (

Table 10. Annual costs incurred by siltation of dams (×1 million USD).

Homogeneous Zone	Economic Cost (Million USD)
1	7.1
2	16.7
3	12.8
4	7.6
5	6.4
6	5.5
7	3.3
8	2
Total	61.6

), established on the basis of the economic costs of dam silting by catchment area (Appendix A.3).

4.4. Degradation of Carbon Storage

Implementation of the InVEST carbon storage and sequestration model has given us the quantity of carbon stored between 2000 and 2020 (Appendix A.1) in Morocco and by homogeneous zone. The carbon storage lost in Morocco between 2000 and 2020 is 12.48 10⁷ t, representing a loss of USD 7.77 billion over a 20-year period, i.e., an average annual loss of 6.24 10⁶ t and an average annual economic cost of 390 (million USD/year) for the Kingdom (

Table 11. Annual costs incurred by loss of carbon storage between 2000 and 2020 (×1 billion USD).

Homogeneous Zone	Percentage Variation (%)	CO2 Sequestered Between 2000 and 2020 (107 t)	Economic Cost (in Billions of USD)
1	−2.96%	15.4	9.58
2	−3.81%	1.76	1.10
3	−43.96%	2.28	1.42
4	−5.85%	26.32	16.38
5	19.47%	3.51	2.18
6	−13.81%	11.64	7.25
7	4.40%	8.28	5.15
8	−2.96%	2.63	1.64
Total		12.48	7.77

).

4.5. Land Use Trends

Evolutionary trends, using 2001 as the reference year (value = 1), highlight the non-linear nature of land use transformations. Some land occupations show an overall upward trend, others a downward trend, while some evolve in an increasing manner during one period and regressively during another (Figure 7). The annual change matrix obtained enabled us to ascertain the average evolution of each land use, namely a decline in cultivated land (19,084 ha), grassland (12,857 ha), and wetlands (87 ha), and a net increase in forest (796 ha), representing an annual lost cost of USD 11.55 million for land use change.

4.6. Total Annual Economic Cost of Desertification in Morocco

The total annual economic cost of desertification in 2020 is estimated at USD 2.1 billion (

Table 12. Total economic cost of desertification in Morocco (billions of USD).

Degradation	Economic Cost (Billion USD)
Degradation of agricultural land	0.6
Degradation of rangelands through overgrazing	1.04
Degradation of carbon storage	0.39
Siltation of dams	0.06
Land use changes	0.01
Total annual economic cost of desertification in Morocco 2020	2.1

), representing 1.77% of Morocco’s GDP, with degradation of agricultural land accounting for 28.75% of the total cost, and degradation of rangelands through overgrazing, degradation of carbon storage, siltation of dams and changes in land use accounting for 49.27%, 18.47%, 2.95%, and 0.56%, respectively (Figure 8).

5. Discussion

Determining the economic cost associated with desertification is intrinsically complex, and its relevance is inextricably linked to the accessibility of relevant knowledge and information. Thus, the material losses considered in this study reflect only a limited fraction of the impacts of desertification, which are likely to be underestimated. The conceptual approach adopted to assess the cost of desertification-related degradation focuses on the most prevalent and significant cases without claiming to encompass all possible situations.

To estimate the costs of desertification and land degradation, “in situ” effects such as water and wind erosion, overgrazing, salinization, carbon stock degradation, and land use change have been addressed, as well as “ex situ” effects, including water loss in dams due to transport of surface soil horizons and siltation. The data needed to estimate these degradations are the land area and its occupation, the degree of degradation, and the consequent variation in agricultural and pastoral productivity. The prices of agricultural and forestry products, the social cost of carbon, and the total economic value of ecosystems make it possible to estimate the economic cost of desertification in monetary terms.

The total economic cost of desertification is estimated at USD 2.1 billion, or 1.77% of Morocco’s GDP in 2020. Pasture degradation due to overgrazing accounts for the majority of this cost (49.27%), while overconsumption of available forage resources by livestock is estimated at 4.1 billion forage units per year. Homogeneous Zone 5 is the most affected, with pressure corresponding to 25% of overconsumption. The loss of productivity of agricultural land through water and wind erosion and salinization results in a loss of more than 20 million quintals of agricultural production and accounts for 28.75% of the total cost of desertification. Wind erosion causes the most losses, and homogeneous Homogeneous Zone 7 is the most degraded. With regard to the degradation of carbon storage, more than 6 million tC is lost annually and its cost represents 18.47% of the total cost, with Homogeneous Zone 4 losing the most storage. The effects of ex situ water erosion, manifested by the silting-up of dams, account for 2.95% of the total cost, with homogeneous Zone 2 suffering the most damage. Land use change accounts for the smallest share of the total economic cost of desertification, at 0.56%. Analysis of change over a 20-year period shows that there has been an annual decline in cultivated land (19,084 ha), grassland (12,857 ha), and wetlands (87 ha), and a net increase in forest (796 ha). Evaluating the cost of degradation by homogeneous zone, the seventh homogeneous zone is the most affected by degradation with a cost exceeding USD 580 million, followed by the sixth with a cost exceeding USD 420 million, while the least degraded homogeneous zones are the first (USD 47.25 million) and second (USD 42 million).

It is essential to continue efforts to better understand the causes and dynamics of soil degradation in Morocco. This requires the development of more in-depth analyses to obtain more accurate and comprehensive estimates. In addition, carrying out cost/benefit studies could help to identify interventions that have the greatest positive impact on the environment while remaining economically viable. To guarantee sustainable management, it would be advisable to set up a rigorous monitoring and evaluation system based on observatories that are well distributed across the homogeneous zones identified. These efforts should not be limited to the physical and biological aspects of combating degradation but should also include social and economic dimensions, with the active participation of local communities. Finally, it is imperative to promote sustainable agricultural and land management practices adapted to the specific characteristics of each region to preserve soils and improve their resilience in the face of climatic and anthropogenic pressures.

5.1. Comparison with Earlier Studies

This study’s findings align with and expand upon those of [12], who estimated that environmental degradation costs Morocco 3.52% of its GDP. While their research provided a comprehensive assessment of environmental degradation, including urban and industrial factors, this study focuses specifically on desertification-related land degradation. The economic cost of desertification in this study, estimated at USD 2.1 billion (1.77% of GDP), reflects a narrower scope but provides greater detail in terms of zonal analysis and specific drivers such as overgrazing and wind erosion.

Additionally, ref. [12] highlighted the significant role of land degradation in rural poverty, a finding corroborated here through the identification of homogeneous zones 5 and 7 as areas bearing the highest economic burden. Unlike their broader approach, this study incorporates newer datasets and advanced tools, such as the InVEST SDR model, to achieve spatially explicit insights. By using a zonal approach, it advances prior findings by revealing spatial variability in degradation impacts and the economic consequences for specific zones.

Moreover, while [12] emphasized the broader implications of environmental degradation on Morocco’s economy, this study underscores the specific mechanisms of desertification and provides actionable recommendations for land management tailored to each zone. This targeted approach offers a framework for prioritizing interventions and allocating resources efficiently, thereby advancing earlier findings.

5.2. Public Policy Recommendations and Comparative Analysis

To address desertification, Morocco should strengthen land use planning, promote ecosystem restoration through reforestation and soil conservation, and modernize irrigation systems to combat salinization. Sustainable agricultural practices such as no-till farming and crop rotation, coupled with community engagement, are vital for long-term success.

Morocco can learn from regional examples like Tunisia’s Land Degradation Neutrality targets and Jordan’s water harvesting techniques, as well as global initiatives like China’s Loess Plateau restoration and India’s watershed programs. These highlight the value of integrating traditional knowledge with modern solutions. Morocco’s PANLCD provides a strong foundation, but scaling up region-specific interventions and monitoring systems will enhance its effectiveness.

6. Conclusions

The findings of this study reveal that land degradation in Morocco is a significant and ongoing issue, affecting more than 90% of its territory and generating significant economic costs. This study estimates the total cost of land degradation at USD 2.1 billion per year, representing 1.77% of Morocco’s GDP in 2020. Among the various forms of degradation, rangeland overgrazing contributes the most (49.27%), followed by the loss of agricultural land productivity (28.75%), carbon storage degradation (18.47%), dam siltation (2.95%), and land use changes (0.56%).

The findings reveal that certain homogeneous zones, particularly Homogeneous Zone 7 and Homogeneous Zone 6, bear disproportionate economic burdens due to high pressures on natural resources. In contrast, homogeneous zones 1 and 2 are the least affected, reflecting significant spatial variability in degradation impacts. Despite the robustness of the methodologies employed, this study acknowledges several limitations, including the lack of field validation for certain parameters (wind and water erosion) and the use of temporally non-harmonized data. These limitations highlight the need for updated climatic and environmental datasets and the establishment of monitoring systems tailored to regional characteristics.

To mitigate the impacts of desertification, targeted efforts must be implemented, such as:

• Strengthening sustainable land management practices for agricultural and rangeland areas.
• Promoting ecosystem restoration in the most sensitive homogeneous zones.
• Implementing a monitoring and evaluation system based on region-specific indicators.
• Engaging local communities in conservation initiatives to ensure long-term sustainability.

In conclusion, this study underscores the importance of addressing desertification as a national priority, not only due to its environmental implications but also its economic consequences. The results provide a solid foundation for guiding policies and strategies to mitigate desertification effects while promoting sustainable development.