Navigating the Sustainability Conundrum of Construction Sand

Abstract

Sand is the backbone of modern civilization and faces heightened demand in the Anthropocene. The uncontrolled extraction of sand raises concerns regarding its irreversible ecological impact. The sand industry is not well understood, especially from the perspective of sustainability. To address this knowledge gap, this systematic review combines policy analysis with the use of material flow analysis (MFA) indicators, environmental externalities, and geopolitics to assess the overall sustainability of the sand industry. By utilizing trade data, this study identified the primary importers and exporters of sand within each continent and selected the top 3–4 countries for analysis. Based on these countries, relevant studies in the literature on the trade and domestic extraction of sand and that used the principles of MFA were found to assess the patterns of its consumption. Illicit sand mining adds a further challenge regarding data accuracy and verification. This study revealed that China’s consumption of sand surpasses that of all the other countries studied, at 17,700 million tonnes, and China has the highest mass of recycled aggregates in use. Using gross domestic product as a proxy for size of the economy, it was found that China consumed 0.001251 million tonnes of sand per million USD. European nations showed a striking balance in their sand industries by placing equal importance on using virgin sand and recycled aggregates, thus contributing to a circular economy. The use of MFA for future research can reveal hidden flows by positioning itself as a science–policy interface, enabling greater circularity within the lock-ins of the construction sector.

1. Introduction

1.1. The World’s Reliance on Sand

The phrase “most extracted material” conjures images of coal mines, vast swathes of forests being cleared, or massive pits being dug in the earth to extract mineral ores. Yet, in reality, the most extracted material today is sand, which surpasses extraction of fossil fuels [1]. At present, a staggering maximum of 59 billion tonnes of material is estimated to be mined [2], of which almost 85% consists of aggregates such as sand, with no signs of their demand and extraction decreasing [2]. In the Anthropocene, demarcated by increased consumption and anthropogenic activity affecting natural elements, humans have found ways to alter natural cycles, including that of sand. Intertwined with the sediment system, the way in which sand flows indicates many aspects of anthropocentric destruction. When excess sediment flow is present, it indicates changes in land use, deforestation, or mining, while a decrease in or dearth of sand flowing can be attributed to diversion of the flow of water channels or the building of dams [3]. Regarding the consumption of sand, it is mostly used “to build”. Between 1950 and 2018, the United Nations recorded 33 megacities (cities with a population greater than 10 million), with 27 of them being located in the Global South [4]. To support such a big population, cities need to construct houses, offices, institutions, and roads—for which sand is essential. Sand use in buildings is estimated to increase to approximately 45% between 2020 and 2060 [5]. Annually, an estimated 40 to 50 billion tonnes of sand are extracted from local and transboundary sources, and the demand and extraction rates of sand are likely to increase by as soon as 2030, as more and more cities are projected to become megacities [4].

Sand is needed for much of what humans use in their day-to-day lives—from the houses they live in to the glass used in houseware and the asphalt they drive on, all of these items require sand as a building material. It can be difficult to grasp that sand shortage is an issue, with deserts containing vast amounts of it, but desert sand grains are too smooth to work as a binding agent for concrete and other products [6]. As a result, most sand used for making cement, glass, concrete, etc., is mined from riverbeds, lakes, deltas, and streams [7].

Sand is a complex material, making it difficult to monitor and track. As a common-pool resource [1], sand is cheap to extract and transport with no penalties or limitations, so very little attention is paid to the volumes of sand extracted for commercial use [8]. Matters become challenging when it is considered how sand is extracted from transboundary rivers, with this work predominantly constituting an informal sector in developing countries [9]. Thus, besides the work performed in China [10], no other studies have investigated the implications of sand extraction, despite significant media outcry highlighting these concerns [11]. As a result, global records on sand are scarce [2].

Such unpreparedness can have lasting implications in this era of heightened climate-change-induced disasters. With the increase in ravaging wildfires, heatwaves, and devastating floods, it is clear that climate change is intensifying natural disasters [12]. In such instances, disaster recovery is imperative. However, among pressing issues like land use change and desertification, disaster recovery can become challenging to navigate. With increasing urbanization, it is no surprise that the consumption and in-use stocks of sand have increased around the world [13]. As a result, in 2015, China reported that approximately 18% of its national area, or 1,721,200 km² of land, underwent desertification [14]. This highlights the urgent need to understand this under-investigated industry, so as to be better prepared for the climate crisis.

1.2. Sand Industry and Eco-Construction

At present, the sand industry is predominantly small-scale and artisanal, especially in developing countries [15]. Depending on the scale of individual mining firms, the extraction process includes either manual digging with shovels and transportation by trucks, or extraction of sand from riverbeds by large dredgers and its transportation in boats and vessels [9]. Over-extraction of sand has been noted in many parts of the world, including the Mekong Delta [16,17], Poyang Lake [18], and other places, which are experiencing ecosystem degradation as well as negative effects on the lives of those involved [8]. This makes the sand industry highly volatile, because it is run by the political economy, which has severe environmental and social consequences [19]. With the threat of an imminent sand crisis [20], investigating the principles of circular economy can provide insights into ways of mitigating this threat. The Ellen MacArthur Foundation, a pioneer of the circular economy concept, defines circular economy as a system designed to reduce ecological footprints on all fronts, with industrial systems designed to reduce waste by finding newer inputs for end-of-life (EOL) products and improving efficiency overall [21]. However, sand needs to be addressed through a different lens. Sand is an intermediate material, which means once it is fed into a manufacturing industry, at EOL, the initial sand will never be recovered. Since the working model of circular economy depends on the way EOL products are used, the sand end products need to be made efficient. Additionally, this will be a major challenge for developing countries, because their existing recycling rates are already low, with only 10% of construction and demolition waste reported in China reported to be recycled [22]. This provides a very strong case for eco-construction to become the standard practice in the future. Through the adoption of better design and technological investment, the way humans build today can be made more circular, enabling the adoption of a cradle-to-cradle approach and thus better material and energy recovery [23].

Eco-construction further opens the discussion for sustainable construction materials, engineered substitutes, and the health impact of construction & demolition (C&D) waste. Eco-construction is not limited to the building of houses, but extends to roads, highways, industries, material recovery and more. A recent study addressing the use of foamed concrete for highways saw that it reduces stress on the transition section, allowing better weight distribution, and increased use of recycled aggregates [24]. Design innovation in the use of geocells for roads can reduce the use of traditional roadmaking materials and help reduce settlement [25]. Innovation in geopolymers by adjusting ratios of elements like calcium and silicon have allowed researchers to make geopolymer stabilized clay, enabling better material recovery and use [26]. In the age of artificial intelligence, researchers have also used it to better understand certain types of sand, like calcareous sand to improve the way foundations in coastal environments are simulated [27], which can then consequently lead to better design choices. In the realm of health impacts of C&D waste, researchers have highlighted the need for better policies concerning the optimization of construction management to reduce pollutants [28] to improve overall human health of those involved with the industry. While these are impressive leaps taken to improve the understanding of circular practices and innovation, such conversations cannot be expanded unless there is better comprehensive understanding of sand sustainability.

1.3. Global Lack of Research on Sand

The lack of data on this industry represents the biggest hurdle in this field. Finding research that addresses the current status, sustainability factors, and implications of sand mining most often leads to a dead end. The few existing studies on sand are unreliable, and this stands true on a global scale. The reasons for this lack of research raise red flags about the sand industry. Sand mining is largely illicit and informal in nature, which makes the task of collecting data incredibly challenging [29]. The sand industry is a fragmented one with limited regulatory measures, which compounds the issue of recording and monitoring, leading to further knowledge gaps [30]. Therefore, national databases and statistics are unreliable sources of information, especially for developing countries. Sand falls under the aggregate industry, which comprises multiple materials like gravel, cement, concrete, and asphalt; these represent the backbone of the construction industry [31,32]. Since sand is also an intermediate component for making cement, concrete, mortar, and asphalt, it is easily misunderstood and not accounted for directly, as it is only an ingredient and is thus secondary to more well-known resources like cement [30,33].

In fact, examining cement as a resource led to the identification of the research gap for sand. Since sand is an essential element to making cement, and concrete, all stock-based work on sand was done by back-calculating to estimate how much sand was used [13]. It was also noticed that academic literature spoke about the environmental externalities of the sand industry in a very scattered way, with little attention paid to the geopolitical aspect concerning the illicit trade of sand. The latter was covered extensively through gray literature and media coverage. This led to the understanding that a combined work reviewing the global industry from an MFA, environmental issues, and geopolitics point of view would provide a scholarly picture, albeit incomplete, over what the present sand industry looks like.

However, this research faces increasing uncertainties. The sand industry receives significant media coverage; however, the secretive nature of the industry is reflected in the lack of quantitative data recorded. This explains the lack of academic research on sand. Another concern is related to how UN Comtrade works. It is up to individual countries to report their trade data, and when they do not do so, the value remains at zero; however, this does not mean that there was no trade. The nuances of these challenges are further elaborated upon in Section 2.6.

1.4. Significance and Objectives of This Study

Very little is known about the sustainability of the sand industry in comparison to resources like plastics or metals, as it has received little attention due to illegal mining and sand mafias, in addition to the overwhelming scale of the sand trade across countries. Public databases fail to incorporate sand data because, while the sand market is huge, it is still cheaper than other mined resources like ores, precious metals, and fossil fuels [34]. The lack of quantitative studies on the sand industry is prevalent for all countries except China, where researchers conducted a material flow analysis (MFA) for its sand and gravel stocks [10], setting it apart from the qualitative approach taken by other scholars. Additionally, reports by the UN or stock focused studies estimate sand use from the estimation of the amount of sand needed to make cement. Other studies have investigated sand sustainability from a supply-chain perspective [35] and through the lens of ecological degradation with a focus on governance [36]. The work of Bendixen et al. (2021), looks in detail at the sustainability of the sand industry through the lens of the Sustainable Development Goals [8]. This highlights the fragmented nature of the work surrounding the sustainability of this industry, with little scholarly knowledge available addressing the geopolitics concerning sand. However, no studies have considered actual quantitative masses of sand in conjunction with trade indicators, environmental impacts, and geopolitics.

Within such a setting, this study puts into perspective the flows of sand using the framework of social metabolism. The extraction and consumption of sand follows a stock-flow dynamic, while having implications on local resource depletion. This sets up the scene for geopolitics surrounding this resource at a time where the demand is only increasing. The extreme absence of data makes it difficult to discuss the sustainability and circularity of construction materials, given the stark consumption and limited stock availability. Yet, from a policy standpoint the use of data-intensive methods like MFA remains pivotal to discussions surrounding circularity. However, the lack and unreliability of data which is compounded with widespread skepticism has meant that few studies have addressed this resource from a quantitative perspective. Hence, this study acknowledges these issues and aims to create a foundation, wherein sustainability of the sand industry is assessed through a mix of qualitative and quantitative lens.

Therefore, this study, using a mix of policy analysis and stock taking of sand quarrying, consumption, and movement through the lens of typical MFA, addresses the lacuna in this field by connecting the dots of MFA indicators, environmental externalities, and geopolitics, setting the stage for elucidating the position of the sand industry in sustainability domain. Additionally, this study investigates sand mining and the related policies in place across countries, notably India, China, Singapore, countries in the European Union (EU), UK, USA, Canada, Brazil, Peru, Chile, and Australia, to highlight the loopholes and problems that need to be addressed. In brief, this study seeks to understand the broad framework of sand consumption and distribution on an international scale through a systematic review, in order to propose better policies for sustainable use of sand.

2. Methodology

2.1. General Overview

This study utilized MFA for data analysis. It should be noted that while MFA is a very data-dependent tool, this study was conducted on an industry with limited data on a global scale. A systematic review using the PRISMA guidelines and Google Scholar was performed. PRISMA guidelines provide a standardized framework to ensure transparency, reproducibility, and completeness in reporting systematic reviews and meta-analyses [37]. Data was collected in two parts: selecting countries and identifying factors and indicators for trade, extraction, and consumption. Externalities, policies, regulations, and geopolitics were also considered. Trade data for sand was collected from UN Comtrade [38] and supplemented with data from the relevant gray literature. The initial search yielded 15 peer-reviewed articles.

The data was then filtered according to set criteria which included the following:

• Work published between 2016 and 2021;
• Work published in peer-reviewed journals or for which the sources could be verified;
• Work that represented the sand industry on a national scale (and not a local scale, like one town or one river);
• Work where emphasis was placed on the aggregate and glass industries.

This led to the finding of 2 peer-reviewed journal articles for only two of the countries, and for other countries, information was accessed from aggregate associations mentioned in the UN reports [30,39], which could be verified. After this, the findings were summarized, and policy insights were obtained to enable us to draw relevant conclusions. The methodology employed to conduct this review is summarized in Figure 1.

2.2. Defining the System Boundary and the Conceptual Framework Applied for MFA Indicators

2.2.1. System Boundary

MFA quantifies the amount of sand flowing within a system boundary. The sheer lack of research and data, in both developing and developed nations, makes one wonder how a resource with a greater historical footprint than plastic has failed to capture the interest of economists and researchers [40]. Even Ioannidou et al. (2020), who considered sand extraction values from 2009 and 2010, admitted that there is no direct way to investigate the consumption of sand [33]. Anecdotal evidence in the form of media coverage has captured the negative externalities of the industry but made baseless claims in terms of its long-term sustainability. Only MFA can produce insights to spark discussions on proper monitoring, regulation, and governance of the industry. The complexity and diversity of sand as a resource are also why using MFA is vital for improving the sustainability of this industry in the future. This study investigated the basic MFA indicators for sand industries, which refer to the national boundary as the system boundary. Figure 2 depicts the general conceptual framework used for data collection from peer-reviewed articles, reports from renowned organizations, verified aggregate association websites, and reliable gray literature.

2.2.2. MFA Indicators

Given the limited data available, this study utilized simple MFA indicators, including the following:

• Domestic extraction (DE);
• Import (I);
• Export (E);
• Domestic Material Input (DMI), where DMIsand = Isand + DEsand;
• Domestic Material Consumption (DMC), where DMCsand = DMIsand − Esand;
• Recycling rates (if any data were found).

It should be noted that the use of the equation above refers to how the values obtained from the sources were interpreted. Thus, if a country reported a value for the mass of sand extracted, it was assumed that the value represented the DMIsand, unless stated otherwise. Since DMIsand influences DMCsand, there are a couple of nuances to note here. Owing to the lack of standardized global datasets, many countries often report sand together with gravel, or have varying definitions of what they consider to be sand. This can consequently influence the value for DEsand and can bias DMIsand and DMCsand.

Another clarification to be addressed is that sand and aggregates from historical DMC demolitions would have ended up in landfills because the recycling market for these materials remain small. Thus, there is no risk of double counting because the sources are from previous DMCs. An issue that may arise is that many companies create aggregates, and during the process, the waste is produced and recycled back into production as a continuous process. For this study, no such mentions were found in any of the sources. To prevent the possibility of double counting, any information found on the mass of recycled aggregates that contained such inputs would be subtracted.

Since the study relied on a big portion of gray literature for these values, the reliability of the data remains questionable as many sources simply state the mass of sand demanded at a certain year, with no way follow up on how much sand was used. Thus, no country specific models were built due to concerns of data gaps and reliability.

2.3. Country Selection

Multiple approaches were used to derive the final country list for this study. Initially, the basis for selecting countries was their gross domestic product (GDP) and urban growth rate, obtained from the World Bank [40]. After taking the year-over-year growth for each country, from 1981 to 2021, the averages were calculated to determine which countries had the highest GDP within each continent. This method was justified because the greater the urban growth and income growth rate, the greater the need for building infrastructure, which will inevitably lead to more sand use. However, this method was not employed, because GDP alone is not the most accurate representation of income or income growth. The urban growth rate average was calculated over 5-year intervals, predicting increased demand for construction materials and sand. However, the countries consuming the most sand are not necessarily the ones with the greatest urban growth, and developed nations remain the largest consumers. The method of examining gross national income (GNP) and its rate of change to determine the highest increase in sand consumption was not employed, as it did not correlate with the largest sand consumers in countries with GNI growth.

Looking into other methods led to the use of the OEC database [41], which uses the Harmonized System Codes (HS codes), to see the top importers and exporters of sand in the world in terms of trade value. This method applies to all of the continents except Antarctica. For each continent, the top importers and exporters were looked at, which were found to be congruent with the countries in which studies have been published and that are reported to use a lot of sand.

Therefore, the countries chosen were as follows:

• Asia: China, India, and Singapore.
• Europe: Belgium, Germany, the Netherlands, and the United Kingdom.
• North America: United States and Canada.
• South America: Brazil, Chile, and Colombia.
• Africa: Egypt and Morocco.
• Oceania: Australia.

Table 1. Studies selected for this study.

Title	Country	Type of Document	Reference
Stocks and flows of sand, gravel, and crushed stone in China (1978–2018): Evidence of the peaking and structural transformation of supply and demand	China	Journal Article	[10]
News from India	India	Newsletter	[42]
Estimates of Aggregates Production (2019 Data)	Belgium	Aggregate Association Website	[43]
Estimates of Aggregates Production (2019 Data)	Germany	Aggregate Association Website	[43]
Estimates of Aggregates Production (2019 Data)	The Netherlands	Aggregate Association Website	[43]
UK Minerals Yearbook 2021	UK	Report	[44]
Mineral Commodity Summaries 2020	USA	Report	[43]
Annual Statistics of Mineral Production	Canada	National Statistics Website	[44]
News from Brazil	Brazil	Newsletter	[45]
News from Chile	Chile	Newsletter	[44]
News from Colombia	Colombia	Newsletter	[46]
2017–2018 Minerals Yearbook, Egypt (2018 Data)	Egypt	Report	[47]
Political settlements and the historical development of sand governance in Morocco	Morocco	Journal article	[48]

shows all of the studies selected for this study.

2.4. Environmental Degradation and Social Impacts of Sand Mining, and Gauging Its Sustainability

A simple scoping search was performed to evaluate the environmental degradation and other impacts of sand mining. The impacts were selected based on the connections between sand mining and its impact on the environment and people. To achieve this, the following broad categories were created: impacts on land, water, biodiversity, and people. Then a literature search was conducted to determine which effects were commonly discussed and chose impact categories for the study. The shortlisted effects were as follows:

• Biodiversity loss/disruption to biodiversity;
• Changing of water levels and water tables;
• Poor river health/damage to river channels;
• Erosion;
• Flooding;
• Damage to riparian vegetation;
• Disrupted sediment flow;
• Loss of property and livelihoods.

For each of these effects in all of the selected countries, a detailed literature search was conducted by setting the effects as keywords followed by the country. Then, the literature was scanned to determine if sand mining was the predominant cause of each of the shortlisted impacts. Based on the results, a color-coded table was constructed, showing whether each impact was observed, if any transboundary impacts were present, or if no literature was found for the selected country. All of these are recorded in Section 4.

2.5. The Geopolitical Agenda

A similar approach was conducted to unearth geopolitical agendas in relation to sand. The countries were listed as keywords, and any evidence of conflict and unrest due to sand mining was identified. Here, newspaper articles were included to broaden the scope of the search. The prime focus was on whether sand mining is an ethical industry. In cases where it was determined to be unethical, this part of the study identified the reasons, the actors, and those who are affected by the geopolitical agenda of sand mining.

2.6. Challenges Encountered During the Course of This Study

Data collection revealed problems with heterogenous reporting and interpretation of aggregates, which can refer to various materials, like sand, gravel, marine aggregates, recycled aggregates, crushed stones, and manufactured aggregates. The USA, in their Mineral Commodity Summaries 2020 [43], separated construction and industrial sands, but no other countries have made such a distinction. This confusion affects the determination of sand consumption, as sand and gravel are essential components of the aggregate industry. The European Union and countries like China report sand and gravel extraction values together, but trade statistics consider them separate entities, making domestic extraction uncertain. Different aggregates and gravel types contribute to this uncertainty. Furthermore, the discrepancy in the mere availability of data was a shock while conducting this study. Since the data source for Canada was an online website, it was noticed the data for 2021 had changed since the last time the calculations were worked on for this research. On top of that, it was noticed that the source used for obtaining data for recycled aggregates was missing when a search was made for it.

In some cases, the national-scale and timeframe criteria were not fulfilled. Studies like [19] and [49] only focused on a particular area of the countries they were investigating (South India [19] and Northern Brazil [34], respectively). Due to the scattered nature of the literature found, it was difficult to keep the year of data collection the same across all studies. However, between the continents, the years were kept the same where possible. The raw data [10,38,41,42,43,44,45,46,48,50] used for this research has been provided in Table S1: Sand article Supporting Information.

3. Global Sustainability of Sand Through the Lens of MFA

3.1. The Input of Sand Industries and What It Depicts

In terms of total Domestic Material Input, or DMI, which is the summation of the domestic extraction, recycled inputs, and import of sand, the top five countries are China, India, USA, Brazil, and Germany. However, directly comparing the values of the sand extracted in these countries is futile, as there are many variables that dictate the volume of sand extracted. This can include the size of the country, the natural resources available, the sand required to meet development needs, the presence of alternatives, and many other factors. Each of these factors can influence the amount of sand needed. Thus, the data was normalized against the land area and the population size to give us a better idea of the consumption of sand per capita. This allowed for better comprehension and comparison of the values of DMI across the countries chosen for this study.

When the DMI is normalized against the country size, the top five countries on the list are Singapore, China, The Netherlands, Germany, and Belgium. From this perspective, the small island nation of Singapore has the largest input of sand, whereas China, with a much greater country size, ranks second.

When the DMI is normalized against the population size, the top five countries are China, Singapore, Canada, The Netherlands, and Germany. It is also notable that India, despite having the second-largest population, is not on this list once the sand inputs are normalized.

Interestingly, when the inputs are normalized this way, China and Singapore are consistently at the top of the list, indicating high inputs of sand per land area and per capita.

The total inputs can be dissected further by investigating their types. This illustrates the nature of the world’s dependency on the sand industry (Figure 3), in which it is clear that domestic extraction plays the biggest role. In Asia, Singapore is seen to be entirely import-dependent, as it is an island nation that has exhausted its own sand reserves. As a result, it relies heavily on imports to meet its demands. Of all of the Asian countries, China has a minuscule proportion of input from the recycling sector, with 200 million tonnes, which is the highest recycling input of all of the countries included in this study.

3.2. Consumption Patterns

Since the calculation for consumption was performed based on the principle of mass balance, the direct material consumption is very similar to the direct material inputs. The results show that the differences between DMI and DMC are very low, owing to low overall exports of sand. Singapore, which is entirely import-dependent, had a linear flow, where all the sand they imported went straight into inputs. Since Singapore reported negligible exports, all of its inputs were consumed within its system boundary.

China’s consumption of sand is exceptionally high, making it appear as an outlier in the results. In Figure 4, the consumption pattern is compared across the other countries by adding the results.

However, when China is removed, variations can be seen across continents. Figure 4 below shows that Asia has the highest consumption of sand, while Europe has low to medium sand consumption. In Africa, a trend of low consumption was noted. Towards North America, a medium to high consumption pattern can be seen, and lastly, South America shows a low to medium trend, moving towards high consumption.

Addressing Consumption with Respect to Gross Domestic Product (GDP)

Since the reliability of the data used in this study remained unverifiable except for China, a simple calculation was done to see the consumption of sand with respect to the size of the economy. In this calculation, GDP is acting as an indicator for the size of the economy. Since China had the largest DMC among all the countries, the GDP of the year the data was from was taken from World Bank [46]. DMI was then divided by the GDP to see what the consumption of sand looks like compared to the size of the economy. This revealed a value of 0.001251 million tonnes of sand consumed per million US Dollars. By comparison, when repeated with India, which had the second largest value of DMI, a value of 0.000530 million tonnes of sand consumed per million US Dollars is seen. This highlights that China’s consumption of sand with respect to the size of their economy is approximately twice than India.

3.3. Recycling Aggregates

Recycled aggregates are being used, albeit little, to reduce the use of virgin sand in the construction sector. The arena of recycled aggregates is a rather complex one, owing to the variety of materials that can be retrieved from C&D waste. The EU sets directives for C&D waste based on the type of material obtained from demolition. The remaining materials are recycled similarly to other materials; they are collected, transported, screened, washed, and dried to then be used as recycled aggregates in new construction [47].

China has the highest usage of recycled aggregates in their sand industry, at 200 million tonnes [10], but compared to their consumption patterns, this amount is too low for long-term sustainability. European nations’ usage of recycled aggregates pales in comparison to that of China, with Germany using 72 million tonnes [43], the UK using 64.9 million tonnes, The Netherlands using 22.5 million tonnes [43], and Belgium using 22 million tonnes [43]. While Belgium’s contribution might look small, recycled aggregates make up a significant portion of Belgium’s construction sector, and Germany follows the same trend as Belgium. The USA is a big consumer of sand; however, no data could be found regarding their use of recycled aggregates.

4. Act II: The Unseen Impact of the Sand Industry on the Environment

The sand industry’s reported impacts on the environment, including the loss and disruption of biodiversity, alterations in water levels and water tables, compromised river health and damage to river channels, erosion, flooding, harm to riparian vegetation, disrupted sediment flow, and the consequential loss of property and livelihoods, are shown in Figure 5.

Sand mining’s predominantly negative impacts are apparent in several countries, as is the clear lack of research in this area. China and India have reported disruptions in biodiversity [51,52], changes in water tables [53,54], poor river health [54,55], erosion [56,57], flooding [58,59], damage to riparian vegetation [17,60], disrupted sediment flow [17,61,62], and loss of livelihoods [6,19] as a result of sand mining.

Singapore is an import-heavy country, and because it imports sand from other countries, the source countries are the ones that bear the environmental burden. The countries directly involved with supplying sand to Singapore include Cambodia and Myanmar. Cambodia reported a loss of biodiversity and livelihoods in its coastal communities [63] as well as increased flooding [64]. Myanmar reported increased erosion of its riverbanks [64,65] as well as disrupted sediment flow and poor river health due to sand mining, and the same issues were reported by Vietnam [66].

Overall, Europe showed hopeful results. In terms of biodiversity loss, the UK, Germany, The Netherlands, and Belgium have preventative measures in place to reduce the negative impacts of sand mining [67,68,69,70]. The impacts of sand mining on riparian vegetation are yet to be studied. In the UK, erosion and disrupted sediment flow were noted [71,72]. For Germany, no studies have been found in the literature for flooding and loss of livelihoods, but changes in water tables and erosion were noted [73,74]. Both positive and negative impacts were observed for river health and disrupted sediment flow [69,73], as the studies were conducted at different locations within the country. Belgium showed that sand mining can be carried out without causing long-term damage to the environment. Studies showed that changing water tables, poor river health, erosion, flooding, and disrupted sediment flow were all low due to the replenishment of extracted sand by natural cycles [75,76]. No literature was found on loss of property and livelihoods. Being neighbors with Belgium, the Netherlands had similar results—improvements in terms of erosion, flooding, and sediment flow due to sand mining [77,78].

North America reported adverse impacts of sand mining on multiple fronts. The USA alone reported severe damage to their sand sources, yet no studies mentioned loss of livelihoods [11,79,80,81,82]. Canada reported a loss of biodiversity and depleting water tables [83], but also reported reduced erosion, flooding, and sediment flow [80,84,85]. Damage to riparian vegetation differed between the studied sites, with some studies reporting damage, while others saw improvements to riparian vegetation [86,87,88]. Loss of livelihoods was noted in Canada and Costa Rica, where many Canadian sand mining companies are situated [89,90].

South America reported negative impacts on all areas of environmental damage. Biodiversity losses due to sand mining were observed in Brazil, Chile, and Colombia [49,91,92,93,94,95,96] alongside changing water tables [49,96,97], poor river health [96,98,99], erosion [98,100,101], flooding [49,100,102], and disrupted sediment flow [99,100,103]. In Colombia, only effects on riparian vegetation were not studied; however, damage to riparian vegetation was noted in Brazil and Chile [96,101]. The Amazon, which is home to many Indigenous people and those with subsistence livelihoods, is heavily impacted by mining of sand and precious minerals [104,105,106].

The lack of studies in Africa made it difficult to determine the environmental damage in Egypt and Morocco. No literature was found for any of the environmental impacts in Egypt. Morocco reported the following externalities of sand mining: loss of biodiversity, erosion, disrupted sediment flow, damage to riparian vegetation, and loss of livelihoods [107,108,109].

While very little information was found on the sand mining sector for Australia, negative impacts of sand mining have been noted. The adverse impacts identified included biodiversity loss, poor river health, erosion, flooding, and damage to riparian vegetation [110,111,112,113]. No literature was found for loss of livelihoods or changing water tables.

Some of the studies found in the literature search are too old to align with the scope of this study. However, they are considered in this portion of the study as testament to the importance of learning more about the sustainability of the sand industry. While there are very few studies on the sustainability of the industry, its negative impacts, which can be local or transboundary, are clear. The status of the literature on this topic clearly indicates the need for more research on the extent of the damage caused, the mechanism of occurrence of such damage, and methods to adapt to or mitigate adverse effects of sand mining.

With the climate crisis increasing the frequency and intensity of natural disasters, one must consider that sand mining, as well as the aforementioned environmental externalities, may be connected to these disasters. If mining increases specifically from rivers, then there is heightened risk of weakening the barriers that prevent flooding [17]. If the extent of desertification increases, then people might shift to unsustainable mining of sand as an alternative source of income, increasing the amount of sand mined; paradoxically, sand mining has been seen to degrade soil quality in the first place [114]. Lastly, with the current scale of overdevelopment, the demand for sand will only increase, creating feedback loops of unsustainable practices that will weaken sand systems due to increased sand extraction [8]. When all these dots are connected from the perspective of sand mining, it becomes clear that this could become a global issue of unprecedented scale.

5. Geopolitics, Conflicts, and the Global Sand Crisis

Sand, a vital building block for human development, has given rise to conflicts due to increased demand, weak governance, and bans. Balancing demands and maintaining geopolitical agendas is a challenge, as a simple conflict or feud could tip the balance in an already unstable industry [115].

5.1. China and Singapore

The biggest sand-associated tensions are occurring in China and Singapore. China, the biggest consumer of sand, used more sand in the last two decades than the USA has consumed throughout the entire 20th century [6]. A portion of the sand comes with its own share of geopolitical conflict at the South China Sea, with some countries relying on it for land reclamation. Surrounded by Taiwan, the Philippines, parts of Thailand, and Indonesia, the South China Sea is a prime location for marine resource extraction [116], which includes the extraction of sand for creating artificial land [115]. China, Taiwan, the Philippines, Brunei, Malaysia, Vietnam, and Indonesia have claimed ownership of portions of the South China Sea. However, China has been extracting excessive amounts of sand from territories claimed by other countries, mainly Taiwan [117], which could cause a shift and have further implications for global sediment flows.

In addition to China, Singapore’s sand industry is linked to notable geopolitical debates. A small island nation, Singapore lacks domestic sand resources and relies heavily on imports for land reclamation and construction [118] from neighboring Malaysia, Myanmar, Cambodia, and Vietnam. While the trade of sand has contributed heavily to the economies of these neighboring countries, the extent of environmental damage has forced many of them to impose bans on their sand exports to Singapore [119]. All of these countries have reported excessive losses of land and livelihoods after the onset of sand mining [120]. The intensive dredging of sand in Cambodia to feed Singapore’s growth poses a severe threat to Cambodian mangroves and the vulnerable community that live there, with a notable decline in fish and crustacean populations and increased risks of flooding and storm surges [121]. Similar impacts in terms of erosion, loss of islands, and environmental degradation were faced by Malaysia and Indonesia which compelled them to cease all sand trade with Singapore [122]. Despite these bans, Singapore is still growing, which means new countries such as Myanmar are being targeted. Interestingly, data discrepancies exist in the trade records mentioned by Singapore and Myanmar [120], with the work of Lamb et al., reporting that the export mass of sand from Cambodia and Myanmar do not match the import mass of sand of Singapore for the period between 2007–2016 [120]. Consequently, Myanmar has reported environmental damage affecting low-income communities.

5.2. India and Morocco

India ranks directly after China in terms of sand consumption, but the sand trade in India is dominated by the Indian sand syndicate, which is engaged in the illicit mining of sand, leading to the suffering of nature and local communities [123]. Interestingly, a considerable factor in the increased demand for sand comes from a culture shift, where the desire to live in nuclear families rather than joint families is driving up the need for housing [58]. Obtaining a lease or a permit for a state-recognized sand business constitutes much formality, and many people do not have the connections to facilitate this process, which makes illegal mining a faster approach to making profits [124]. Emphasizing the quick-profit aspect of this industry, the syndicate consists of a collection of politicians, local businessmen, powerful individuals in local administration, the police, and laborers who work all year to extract sand despite the obvious environmental consequences [125].

The environmental damage caused by sand mining has been mentioned in the sections above, but what stands out the most is the harm this industry brings to human lives. Corruption allows people in power to get away with crimes associated with the illicit extraction of sand [58]. Cases where state officials have been suspended or eliminated if they have gone against this norm have been noted by journalists across the country [19]. On the other end of the spectrum are the low-income workers who have no other option but to comply with the syndicate or face severe consequences [125]. Activists and journalists are often met with the same fate, no matter how clearly the loss of property and livelihoods is displayed in the media [19]. The fragmented and corrupt nature of this industry and lack of alternative resources to construction sand make it difficult to bring about visible change to achieve a safe and legalized industry [126].

Such syndicates are prevalent in Morocco, as well. What sets this country apart is its historical sand governance, dating back to French rule in Morocco, during which the first regulations on sand mining were established [127]. While these regulations provided a basis for Morocco to establish firm guidelines, their sand industry is still rooted in power dynamics. Much of the sand mining industry is allegedly under the control of state officials, blurring the line between legal and illegal mining [128]. Recent work in Morocco highlighted smuggling of sand from Morocco to feed the demand for Spanish infrastructure, where the illegal extraction, supply, and regulation of the sand industry is carried out by foreign companies, sand traders, and drug trading groups [128]. Loopholes in the regulations enable businessmen, politicians, and foreign powers to keep the illegal sand trade active, but it comes at the expense of degrading tourist spots, high risks of child labor, and intimidation of vulnerable communities, where the power imbalance can silence their voices [128,129].

6. Sustainable Development Goals, Policies, and Possible Solutions

6.1. Current Status of SDGs

The sand industry is directly connected to a country’s development and environment. The extraction, transportation, and consumption of sand has implications across all sectors, and the long-term sustainability of this industry can only be achieved when its impacts are adequately understood [1,9]. The nature of sand mining varies depending on the scale of operations and the types of sources, which makes it difficult to regulate this industry [31,34]. Section 4 highlights the negative impacts of sand mining, which can spread across developed and developing countries. The lack of exploration of environmental impacts in MFA studies worldwide makes it challenging to provide insights on sustainable industry practices.

With that said, the sand industry currently violates every sustainable development goal. While some might argue that the industry provides employment, and the presence of alternatives will change the present scenario, the environmental impacts of the industry represent a major conflict with achieving these targets [8]. This is especially true for developing nations and emerging economies; these nations will see a rapid increase in their demand for sand, which will further fuel the unsustainable extraction of sand [40]. The existence of overlooked health complications, child labor, and bonded labor, followed by the abuse of power by authorities who enable the illicit aspects of the industry, violate human rights, which many of the SDGs aim to protect and improve, such as SDGs 1 (No poverty), 3 (Good health and well-being), 4 (Quality education), 8 (Decent work and economic growth), 10 (Reduced inequalities), and 16 (Peace, justice, and strong institutions) [8,31,130]. Multiple studies have documented the damage inflicted on rivers due to unsustainable mining practices, which jeopardize the quality of land and water while increasing the risk of climate change, thus conflicting with SDGs 13 (Climate action), 14 (Life below water), and 15 (Life on land) [11,16,131].

6.2. Why So Hush-Hush?

The silence regarding the problematic aspects of the global sand trade is damning. Loopholes in local and national regulations, in addition to the absence of a global sand-monitoring body and lack of interests from economists, have allowed corruption in this industry to persist [132]. India and Morocco represent examples of how the involvement of public officials and poor governance encourages illicit sand mining, leading to environmental and socio-economic losses [58,127]. Interestingly, while the impacts of sand mining have been discussed in the literature, only in 2019 did the UNEP shine a light on the fact that at present, the unsustainable nature of sand mining must be addressed before there is a global shortage [11,34]. The transparency of this industry needs to be improved. The sand industry is subject to high levels of under-reporting, and values found in trade databases are often not the absolute amount of sand traded [120]. This happens because restrictions placed on the sand trade encourage illicit mining to meet the demands, none of which is monitored [1].

6.3. Hurdles to Making the Sand Trade Sustainable

Multiple challenges must be addressed to make the sand industry sustainable. Under normal circumstances, in-depth research is suggested to understand the gravity of an issue and provide situation-specific solutions. However, in the case of the sand industry, a recommendation would be in taking a reverse approach starting with the removal of loopholes in the existing regulations, with stricter enforcements and stronger governance. This way, the “untouchable” nature of the sand industry can be eliminated while improving the transparency of the trade at the national level [39]. Around the world, the sand industry operates on different scales, ranging from large scale-private firms to subsistence and artisanal mining; in the case of the latter, the sand industry tends to be fragmented and informal [133]. Therefore, solutions and policies need to be addressed in a situation-specific manner to ensure that they are implemented in a way that achieves effective results. Emphasizing research is also key, as there are countries and zones where research surrounding the sand industry or its impacts is limited. It was noticed that even though the Bay of Bengal is the largest bay in the world, there is very little research on the sand mining carried out in this area. This is an area of research to consider, as all of the major river systems in Bangladesh drain through the Bay of Bengal, a country with four major river systems [134] that are capable of supplying the sand needed to support their urbanization demand, which is expected to reach 56% as soon as 2050. While other notable river systems such as the Mekong Delta [16] and the Yangtze River [14] have been investigated, river systems in Bangladesh have not. This provides room for research on the sand industry in developing economies.

The way forward for the sand industry lies in a change in perspective, appropriate reforms, and prioritizing the environment. From a preservation perspective, sand mining needs to be designated to safe locations, away from biologically active sites, and should not be conducted during mating or spawning season [17,135]. Mining should be based on accurate data regarding the stock, safe removal limit, rate of natural replenishment, method or technique of extraction, and handling of impacts while putting in place a meticulous system of record keeping and reporting. Raising awareness among the sand industry’s stakeholders to make it economically and environmentally sustainable is critical.

Since the construction industry is directly related to the sand industry, applying the principles of the circular economy can yield benefits for the environment and the industry alike. At present, the world generates 3 billion tonnes of C&D waste annually, and this amount is only set to increase [136]. Existing research shows that Europe has been leading the field in exploring avenues that might contribute to a circular economy, while such research is still limited in Asia, where the construction boom has led to concerns regarding material efficiency [137]. Case studies on pilot projects conducted in The Netherlands revealed that to construct buildings conducive to a circular economy, the focus needs to shift towards innovative collaborative design involving partners, business models that enable circularity of materials and energy, and broadening the scope of options for end-of-life buildings [138]. This is a promising sign and represents the key to creating multi-sectoral methods for waste prevention, promoting the reuse of materials, and eco-design [139]. Such measures will make key players in the sand industry responsible and advance the industry towards sustainability while providing room for alternatives to sand in the aggregate industry.

6.4. Policy Implications

This study and its many challenges highlight the need for the establishment of a global data exchange of construction aggregates with sand as a distinct category. The UNEP provides 10 recommendations for improved sand governance, which include recognizing sand as a strategic resource; considering perspectives of all stakeholders; enabling a paradigm shift towards circularity; adopting strategic, integrated, and legal frameworks; establishing ownership to sand resources; better monitoring and reporting; establishing best practices; promoting resource circularity; responsible sourcing; and restoring ecosystems [140]. Each of these suggestions needs to be customized to fit the country’s economy, scale of sand mining, and sand demand. Regular monitoring is key to achieving effective results, for which a global monitoring system needs to be in place that monitors sediment flows and sand, especially for transboundary sand sources to curb illegal trade and monitor extraction sites [9,17].

7. Conclusions

Sand has infiltrated human lives in apparent and imperceptible ways. However, the low-profile, secretive, and informal nature of the industry make it difficult to gauge its sustainability. This study utilizes a systematic literature review method incorporating MFA indicators, environmental externalities, and geopolitics to review the state and impacts of the sand industry to derive insights for better management of the sand industry. This allowed for the contextualization of sand flows through the lens of social metabolism. Sand extraction depicts the classical case of stock-flow dynamics, and when extracted and used, has implications on local resource depletion, setting the scene up for geopolitics in a time where the demand for sand is only increasing. The study also sheds light on the limits of circularity as sand’s nature as a non-renewable, intermediate resource to the construction sector can be a major challenge to circular economy frameworks. The use of environmental externalities clearly displayed the socioeconomic inequalities caused by sand extraction and consumption, tying in with the nature of geopolitics, illicit trading, and informality of the sector regulating the flow of sand.

It was revealed that China surpasses developed and developing countries in terms of its sand extraction and usage, at 17,700 million tonnes. Overall, there are lessons to be learnt from Europe, where a balance is apparent between sand extraction, use of recycled aggregates (between 20 and 30 percent of its total aggregate consumption), and environmental impacts. The sand industry presently exists within a complex web of geopolitics, sand mafia syndicates due to improper regulations, and unsustainable practices related to extraction and use. If left unaddressed, an imminent sand crisis could be triggered by the status quo, as demand for sand is growing exponentially due to rapid developments in the Global South.

At present, due to the stark lack of data, humanity’s knowledge of the sand industry is too vague to propose sustainability measures with confidence. However, reports from all corners of the world on the negative impacts of the sand industry, despite being few compared to the scale of the sand industry, are overwhelming. The lack of homogeneity and transparency of data in this industry remains the biggest limitation for this study and needs to be addressed in the future. Considering the implications of the sand industry for almost all SDGs, establishing a global monitoring and reporting system and a concerted global effort, finding alternatives to sand, and reducing overall demand for sand are all keys to solving the sustainability problem in the sand industry. In doing so, SDGs 1, 3, 4, 8, 10, and 16 can be improved for the people involved with the industry as well as SDGs 13, 14, and 15 allow better protection of the environment.

Additionally, all hope is not lost, as there is growing research on eco-construction and circular economy in the construction sector, with researchers investigating better design, and ways to create loops of materials and energy. Since the developed world has started exploring how to make construction more circular and sustainable, it remains to be seen how these developments can spark innovation in developing countries. With the rapid development in Asia, Africa, and South America, future research should be focused on the ways local materials and knowledge can contribute to eco-construction. Future endeavors in research should also focus on the transparency and standardization of a global sand database. Thus, to make the Anthropocene an era of sustainability, it is necessary for policy makers, producers, consumers, and researchers to come together to increase awareness and make decisions conducive to creating a sustainable and responsible sand industry.