1. Introduction
The United Nations Convention to Combat Desertification (UNCCD) has defined desertification as the degradation of land in arid, semi-arid, and dry sub-humid areas due to various factors such as climatic variations and human activities (e.g., clearing vegetation from the land’s surface, deforestation, and unrestrained animal grazing). Desertification is a significant global, ecological, and environmental problem with far-reaching consequences on socio-economic and political conditions [
1]. It affects different regions with varying characteristics in terms of geography, economy, and social and environmental conditions. In a study conducted by Hai et al. [
2], it was found that several human activities contribute to desertification, including high population and poverty, inappropriate cultivation techniques, deforestation, inadequate legal frameworks, weak management capacity, lack of adequate knowledge, and lack of awareness among the local population. The unsustainable use of land can result in soil degradation, which is commonly referred to as desertification [
3,
4,
5]. In pursuit of higher productivity, exploitation has increased, and humans have disturbed less productive and more delicate lands [
6]. This overexploitation leads to the degradation of vegetation, soil, and water. Desertification is a self-perpetuating process that worsens over time, and as it progresses, the costs of rehabilitation increase exponentially [
7]. Desertification is a major global concern, according to the United Nations Environment Programme (UNEP). It has already harmed 36 million square kilometers of land and affects the lives of 250 million people. If left unchecked, it could displace 135 million people by the year 2045, making it one of the most serious environmental issues facing humanity today [
8]. Nearly 30% of areas in India experienced desertification, according to the State of India’s Environment report for 2019 [
9]. Nearly 40 to 70% of the land in eight states (Rajasthan, Delhi, Goa, Maharashtra, Jharkhand, Nagaland, Tripura, and Himachal Pradesh) has become desertified. Furthermore, desertification has increased in 26 of 29 Indian states between 2003 and 2005 and 2011 and 2013 [
9]. As per the ISRO’s report “Desertification and Land Degradation Atlas of India” [
10], the area of the country under land degradation is reported to be 96.40 mha, or 29.32% of the total geographic area (TGA) of the country, between 2011 and 2013, compared to 94.53 mha, or 28.76% of the TGA, between 2003 and 2005. In 2018–2019, desertification has been increased to 97.85 mha (or 29.77%) [
11]. In total, 1.87 mha of the country’s TGA (or 0.57% of it) have experienced desertification or other forms of land degradation between the years 2003 and 2005 and 2011 and 2013. In arid regions, wind erosion is seen to be the major mechanism of desertification, while water erosion and vegetation degradation are more prevalent in semi-arid and dry sub-humid areas [
12].
The alarming escalation of desertification poses a significant threat to agricultural productivity, exacerbating land degradation and contributing to climate change [
13,
14]. This degradation not only undermines water supply, soil health, and environmental integrity [
15] but also diminishes both the quantity and quality of surface and groundwater resources [
16]. Soil erosion, a consequence of this degradation, leads to substantial losses in vegetation productivity. Moreover, desertification reduces the capacity of soil to absorb water, resulting in heightened surface runoff and elevated flood discharges [
17]. Consequently, flooding becomes more frequent and severe due to increased runoff. Due to a variety of natural or anthropogenic factors, including deforestation, overgrazing, and climate change, rich land can become deserts through the process of desertification [
18]. This process causes the soil to deteriorate, the vegetation cover to decline, and the soil’s ability to retain water to decline. As a result, the soil dries out and loses its capacity to absorb and hold water. On such degraded ground, when it rains heavily, the water cannot penetrate the hard, compact surface of the soil; instead, it runs off, producing erosion and removing the topsoil, which is the most fertile part of the soil [
16]. Gullies and dry riverbeds are created as a result, and they can easily overflow with a strong downpour. The amount of water that is naturally absorbed by the ground is also decreased in a desertified area since there are fewer plants to absorb water from the soil. As a result, there is a higher chance of flash flooding since the water has nowhere to go and can quickly build up, causing a surge of water downstream [
19]. As the land’s capacity to absorb and retain water decreases due to desertification, more surface runoff and erosion occur. The risk of flash floods is heightened due to this and the absence of vegetative cover [
20]. Food security is put at risk because land degradation reduces and endangers food production. Land degradation puts future nutrition at risk by reducing agricultural productivity and activities [
21]. Apart from that, if the socio-economic sector is seen, then a great impact on health, the problem of migration, etc., can be noticed.
Desertification arises from a confluence of climatic and anthropogenic influences. Declining precipitation patterns coupled with unsustainable land use practices, such as excessive groundwater extraction and deforestation, significantly accelerate desertification processes [
10]. The UNCCD leads global efforts to combat desertification and promote sustainable land management through international collaboration and knowledge sharing. Many techniques are used on global to national levels to deal with desertification. Conventional methods such as statistical studies and modeling strategies are frequently used to manage and prevent desertification [
22]. The risk of desertification can be calculated using models like the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE), which are used to calculate soil erosion rates [
23]. The Century model and the GLOBIOM model are used to simulate vegetation dynamics and to forecast land use changes that may affect desertification [
24]. The MEDALUS (Mediterranean Desertification and Land Use) model has gained widespread recognition across various Mediterranean regions, being implemented at national, regional, and local levels. In a notable application, it was utilized within an entire Greek state to evaluate the susceptibility to desertification, employing the four indicators prescribed in the original MEDALUS [
25]. Studies have employed this approach to evaluate the susceptibility to desertification at the regional level in India, with the findings indicating the favorable performance of the technique [
26,
27]. Researchers have used several indices such as soil quality index (SQI), climate quality index (CQI), vegetation quality index (VQI), and socio-economic quality index (SEQI) for predicting desertification zones by integrating several influencing factors [
28,
29,
30].
About half of the area of Satara and Sangli districts of Maharashtra in India is at risk of desertification due to vegetation degradation, water erosion, increasing salinity, and anthropogenic activities in their physiographic divisions [
10,
31,
32]. It is expected to worsen with the changing climate. The methodology adopted by [
10,
11,
12] for identifying desertification is mainly based on the visual interpretation of satellite images of IRS-based sensors such as Linear Imaging and Self Scanning Sensor (LISS-III) and Advanced Wide Field Sensor (AWiFS). Therefore, a comprehensive study using a better methodology is selected for conducting desertification analysis over two districts. Notably, this study aims to identify environmentally sensitive areas to desertification in these districts, which would be helpful in targeted conservation efforts, developing early warning systems and climate change adaptations. The objective of the study is to discuss how remote sensing and Geographic Information Systems (GIS) technology can be used to gather spatial and temporal information about environmental factors influencing desertification. It also employs the concept of four indices—SQI, CQI, VQI, and SEQI—and how they can contribute to identifying environmentally sensitive areas in the two districts for desertification. The MEDALUS modeling technique is also integrated to anticipate vulnerable areas and implement appropriate mitigation strategies to conserve the land from drought and desertification, creating a more eco-friendly environment.
The structure of the paper comprises several sections.
Section 2 describes the study area, data used, and method applied.
Section 3 describes results on SQI, CQI, VQI, and SEQI followed by discussion in
Section 4 and conclusions in
Section 5.
4. Discussion
The geoinformatics-based MEDALUS model was utilized to analyze and map desertification risks in the Satara and Sangli districts of Maharashtra. These maps serve as crucial tools to guide conservation efforts, foster sustainable practices, and target rehabilitation projects in the region. Additionally, they enable policymakers to implement preventative measures, such as promoting drought-resistant crops. Moreover, the maps establish a baseline for monitoring desertification and evaluating the effectiveness of implemented strategies. By enhancing understanding of local desertification causes, this research facilitates targeted interventions, empowering all stakeholders to combat desertification and ensure the sustainability of the land.
The identification of areas at risk of desertification and the development of methods to stop or slow down desertification depends on the mapping of environmentally sensitive areas. Several studies have mapped environmentally sensitive areas for desertification through the integration of indices such as soil quality, climate quality, vegetation quality, and socio-economic quality using MEDALUS modeling [
26,
54]. Similar to this study, the previous studies provide valuable insights into the effectiveness of this approach globally and specifically in the Indian context. In a similar study by [
55], a proxy global assessment of land degradation highlighted the importance of considering multiple indices, including SQI, CQI, VQI, and SEQI, to comprehensively evaluate desertification risk factors. The integration of these indices through MEDALUS modeling allowed for a more nuanced understanding of environmental sensitivity to desertification across diverse regions [
54]. Kaliraj et al. (2024) also did a similar study for the semi-arid regions of southern India [
26]. This aligns with the notion that a multidimensional approach is essential for effective land management and conservation efforts which is consistent with our research findings and conclusion.
Previous studies focused primarily on global and meso levels to predict the probable desertification zones, which are good for overall understanding [
10,
33,
55,
56]. Ref. [
10] finds that Maharashtra encompasses the second highest area under desertification, i.e., 44.93% for the period 2011–2013. Ref. [
56] conducted similar studies in Western Rajasthan and Gujrat. However, predicting and mapping environmentally sensitive areas for desertification at a micro-scale is crucial for targeted conservation efforts, resource allocation, and sustainable land management more effectively. This study is focused on predicting the areas of Satara and Sangli districts of Maharashtra sensitive to desertification and found that 11.81%, 27.87%, and 60.32% areas are in critical, fragile, and potential zones of desertification. It would help us mitigate desertification’s potential detrimental effects on the local ecosystems, biodiversity, and livelihoods. This would also be helpful in similar studies on other micro-scale areas.
The MEDALUS-based predicted desertification map using geoinformatics offers several merits. One advantage lies in its holistic approach, integrating various factors such as climate, soil, vegetation, and land use practices to assess desertification vulnerability accurately [
57,
58]. This comprehensive assessment of desertification vulnerability would aid policymakers and land managers in formulating targeted strategies for mitigation and adaptation. Incorporating qualitative and quantitative data, it identifies vulnerable areas and prioritizes intervention measures effectively, which enhances reliability and applicability across diverse landscapes, thereby serving as a valuable tool for assessing desertification risks [
59]. Despite these merits, this model has also some limitations. One notable drawback is its reliance on input data, which may be scarce or outdated, particularly in developing regions where monitoring infrastructure is limited [
60]. The Census (2011) data are also old, as the latest Census data have not been released by the Government of India. Outdated data may compromise desertification mapping accuracy, diminishing the model’s utility in guiding land management decisions. Moreover, the model’s complexity and technical requirements pose challenges, potentially hindering widespread adoption and limiting its effectiveness in informing policy and management actions.
Although the MEDALUS methodology provides a solid foundation for desertification vulnerability mapping, advancements in the field offer a broader toolkit. Remote sensing and GIS enable large-scale, objective assessments, while the Land Degradation Neutrality (LDN) framework promotes a holistic approach by integrating biophysical and socio-economic factors [
61]. For intricate analyses involving uncertain data, advanced techniques like fuzzy logic and artificial neural networks (ANNs) can be highly effective [
62,
63,
64]. Agent-based models (ABMs) further enhance understanding by simulating dynamic interactions between land users and ecological processes [
65]. Additionally, participatory mapping incorporates valuable local knowledge and perspectives, enriching the vulnerability assessment.
The comparison of these studies underscores the consensus that integrating multiple quality indices through MEDALUS modeling enhances the accuracy and reliability of desertification vulnerability assessments of micro-regions with some merits and limitations as discussed. Through the integration of soil health indicators, climate variables, vegetation cover metrics, and socio-economic factors, researchers can develop holistic maps. These maps facilitate informed decision-making for implementing sustainable land management practices.
5. Conclusions
Based on the MEDALUS modeling, we find that a major part of the study area comes under the potential category (60.32%) distributed over the study area followed by fragile (27.87%) and critical (11.81%) desertification. Soil drainage, plant productivity, soil erosion, water holding capacity, soil temperature, and soil fertility are greatly affected by the texture of the soil. As the slope gradient varied from 0 to 5° in the study area, it did not enhance soil erosion rates thereby, leading to lower desertification.
The greater aridity index of the area is more vulnerable to desertification. In arid and semi-arid regions, higher wind speed is also responsible for both land degradation and desertification. Higher rain erosivity is responsible for higher desertification of the region. Areas with high population densities are affected by both soil erosion and water stress leading to land degradation and desertification. There is huge pressure of rapid population growth rate on natural resources which is further responsible for poverty. The higher illiteracy rates are also responsible for higher desertification as they hinder the understanding of sustainable land use. The lower work participation rate is also responsible for both land degradation and desertification as it creates economic conditions that incentivize unsustainable land use practices.
Therefore, the regions that are vulnerable to desertification exhibit moderate soil quality, low to very low climatic quality, very low vegetation quality, and moderate to low socio-economic quality. Additionally, areas where desertification is a significant concern, are characterized by the presence of other wastelands and current fallow lands with very low soil, climate, and vegetation quality, and low socio-economic quality.
Synthesizing the results from previous studies on identifying and mapping environmentally sensitive areas for desertification using integrated indices through MEDALUS modeling highlights the importance of a holistic approach to combat land degradation challenges worldwide and specifically in the Indian context. Continued research and collaboration are essential to refine methodologies and develop targeted interventions that promote environmental resilience and sustainable development.