Impacts of riverine sand mining on freshwater ecosystems: A review of the scientific evidence and guidance for future research

Abstract

Sand mining (used here as a generic term that includes mining of any riverine aggregates regardless of particle size) is a global activity that is receiving increasing media attention due to perceived negative environmental and social impacts. As calls grow for stronger regulation of mining, there is a need to understand the scientific evidence to support effective management. This paper summarizes the results of a structured literature review addressing the question, “What evidence is there of impacts of sand mining on ecosystem structure, process, and biodiversity in rivers, floodplains, and estuaries?” The review found that most investigations have focused on temperate rivers where sand mining occurred historically but has now ceased. Channel incision was the most common physical impact identified; other physical responses, including habitat disturbance, alteration of riparian zones, and changes to downstream sediment transport, were highly variable and dependant on river characteristics. Ecosystem attributes affected included macroinvertebrate drift, fish movements, species abundance and community structures, and food web dynamics. Studies often inferred impacts on populations, but supporting data were scarce. Limited evidence suggests that rivers can sustain extraction if volumes are within the natural sediment load variability. Significantly, the countries and rivers for which there is science‐based evidence related to sand mining are not those where extensive sand mining is currently reported. The lack of scientific and systematic studies of sand mining in these countries prevents accurate quantification of mined volumes or the type, extent, and magnitude of any impacts. Additional research into how sand mining is affecting ecosystem services, impacting biodiversity and particularly threatened species, and how mining impacts interact with other activities or threats is urgently required.

A Review of the Scope of Artisanal and Small‐Scale Mining Worldwide, Poverty, and the Associated Health Impacts

“…Population growth in Asia and Africa and trends in urbanization are powering an enormous demand for construction materials, as well as glass and semiconductors (Bendixen, Best, et al, 2019). Estimates in annual production range from 35 to 50 billion metric tonnes annually (Koehnken et al, 2020) but are likely higher (Bendixen, Best, et al, 2019). Notwithstanding the environmental impacts, the greater concerns are that demands will soon exceed supplies, and there will be a rush to exploit sand resources on Greenland (Bendixen, Overeem, et al, 2019; Mahadevan, 2019) or in other rapidly deglaciating areas.…”

“…Land reclamation provides another important use for sand. For example, Singapore used sand to expand its land area by 20% from 1960 to 2017 (Koehnken et al, 2020). It is the world's largest importer of sand, a record that will continue into the next decade (Koehnken et al, 2020).…”

Temporal monitoring of vast sand mining in NW Turkey: Implications on environmental/social impacts

“… Biodiversity: Impacts on related ecosystems, destruction of aquatic/riparian habitat, Afforestation, deforestation (Koehnken and Rintoul, 2018;WWF, 2018). Reduction and changes to the diversity and abundance of macro invertebrates and fish populations, increased viability of invasive species (Koehnken et al, 2020). Impact on migratory / local bird species for loss of land and habitat (Lai et al, 2014).…”

“…River-floodplain systems are a preferred source of sand and gravel for a number of reasons: cities tend to be located near rivers so transport costs are low, the energy in a river grinds rocks into gravels and sands (thus eliminating the costly step of post-mining process, grinding and sorting rock), and the material produced by rivers tends to consist of naturally sorted, angular shaped resilient minerals that are preferred for construction (Kondolf, 1997;Koehnken and Rintoul, 2018). As a result, sand is being increasingly produced through environmentally damaging extractive practices in sensitive river ecosystems (Koehnken et al, 2020).…”

Impact of sand mining on the changes of morphological and physical dynamics in Sa’dang River, Pinrang District, Indonesia

“…Removal of material from a river can alter the channel, river hydraulics, or sediment budget, which in turn can alter the distribution of habitats and ecosystem functioning. These types of impacts can be difficult to attribute to sand mining, as they may require long time frames to emerge (Koehnken et al, 2020). Therefore, it is important to analyze time-series data in order to see the pattern of morphological changes over a long period.…”