IMPACT OF SAND AND GRAVEL DREDGING ON THE ENVIRONMENT

IMPACT OF SAND AND GRAVEL DREDGING ON THE ENVIRONMENT

ABSTRACT

Sand and gravel have been used in the construction of roads and buildings for thousands of years. Today, the demand for sand and gravel is increasing. Mining companies, in collaboration with relevant resource agencies, must work to ensure that sand mining is done responsibly.

Rivers are degraded as a result of excessive in-stream sand and gravel mining. In-stream mining causes stream bottom erosion, which can lead to bank erosion. Sand depletion in the streambed and along coastal areas causes rivers and estuaries to deepen and river mouths and coastal inlets to enlarge. It may also result in the intrusion of saline water from the nearby sea. The impact of mining is exacerbated by the impact of sea level rise. Any amount of sand extracted from streambeds and coastal areas is a system loss.

 CHAPTER ONE

1.1  BACKGROUND OF THE STUDY

Sand and gravel have been used in the construction of roads and buildings for thousands of years. Today, the demand for sand and gravel is increasing. Mining companies, in collaboration with relevant resource agencies, must work to ensure that sand mining is done responsibly.

Rivers are degraded as a result of excessive instream sand and gravel mining. Instream mining causes stream bottom erosion, which can lead to bank erosion. Sand depletion in the streambed and along coastal areas causes rivers and estuaries to deepen and river mouths and coastal inlets to enlarge. It may also result in the intrusion of saline water from the nearby sea. The impact of mining is exacerbated by the impact of sea level rise. Any amount of sand extracted from streambeds

and coastal areas is a system loss.

Excessive instream sand mining endangers bridges, river banks, and other nearby structures. Sand mining also has an impact on the nearby groundwater system and the river’s uses by the locals.

Through large changes in channel morphology, instream sand mining destroys aquatic and riparian habitat. Bed degradation, coarsening of the bed, lower water tables near the streambed, and channel instability are all consequences. These physical impacts degrade riparian and aquatic biota and may result in the collapse of bridges and other structures. If extraction continues, the entire streambed may degrade to the depth of excavation.

Sand mining increases vehicle traffic, which has a negative impact on the environment. Where there are access roads

Crossing riparian areas may have an impact on the local environment.

Sand and gravel are widely used in construction. The building industry requires approximately six to seven times more tonnes of sand and gravel for each tonne of cement used in the preparation of concrete (USGS, 2013b). Thus, the global use of aggregates for concrete is estimated to be 25.9 billion to 29.6 billion tonnes per year in 2012. This output is enough concrete to construct a wall 27 meters high and 27 meters wide around the equator. Aggregates also contribute to 90% of asphalt pavements and 80% of concrete roads, and aggregate demand comes from a variety of other industries, including glass production, electronics, and aeronautics. This is in addition to all of the

aggregates used in land reclamation, shoreline development, and road embankments (for which global statistics are unavailable), as well as the 180 million tonnes of sand used in industry. This sand and gravel are mined all over the world and account for the most solid material extracted globally as well as the most raw material used on Earth after water (roughly 70-80% of the 50 billion tons of material mined per year). They were formed over thousands of years by erosive processes and are now being extracted at a rate far greater than their renewal.

Despite our growing reliance on massive quantities of sand and gravel and the significant negative impact that their extraction has on the environment, policymakers have largely ignored the issue and it remains largely unresolved. The general public is unaware of this. Indeed, the lack of global data on aggregates mining makes environmental assessment difficult, and it has contributed to a lack of awareness about the issue. As a result, there is a significant gap between the magnitude of the problem and public awareness of it.

1.2  STATEMENT OF THE PROBLEM

The environmental impact of sand and gravel dredging or mining is enormous; this is because when they see is dredge Excessive mining for sand and gravel in streams degrades rivers. Any sand exported from streambeds and coastal areas represents a loss to the system. Excessive mining of stream sand endangers bridges, river banks, and nearby structures.

With advancements in technology and infrastructure development, the demand for sand and gravel is increasing, and dredging is the only solution to meet this demand. However, if dredging is not controlled, the impact on infrastructure can be disastrous.

1.3  OBJECTIVE OF THE STUDY

The primary goal of this research was to determine the environmental impact of sand and gravel dredging. However, upon completion of the study, the researcher hopes to achieve the following goals:

The effect of dredging on the Lagos bar beach coastal area
Sand dredging’s impact on Nigerian waters
Determine the effects of gravel dredging in coastal areas
Dredging Challenges in Nigeria’s Coastal Area

1.4 RESEARCH QUESTION

The following research question was developed to ensure the successful completion of these studies:

What effect does dredging have on the Lagos coastal area?
What is the impact of sand dredging on Nigerian waters, with a focus on the Lagos coast?
What are the effects of gravel dredging on infrastructure development along the Lagos coast?
To what extent has dredging impacted the region’s infrastructure development?

1.5 SIGNIFICANCE OF THE STUDY

It is hoped that when the studies are completed, the findings will be useful to the environmental agency and coastal guard, which are in charge of protecting the region. The study will also be useful to NIMASA, which is in charge of protecting Nigerian waterways.

Finally, the study will be beneficial to academia, teachers, lecturers, researchers, and members of the general public.

1.6   SCOPE AND LIMITATION OF THE STUDIES

The scope of this study includes the impact of sand and gravel dredging on the Lagos coastal area; however, the study has some limitations, which are as follows:

a) RESEARCH MATERIAL AVAILABILITY: The researcher’s research material is insufficient, limiting the scope of the study.
b) TIME: The study’s time frame does not allow for broader coverage because the researcher must balance other academic activities and examinations with the study.
c) FINANCE: The funding available for the research work does not allow for broader coverage because resources are limited due to the researcher’s other academic bills.

 1.7 DEFINITION OF TERMS

DREDGING

Dredging is an excavation activity that is typically performed underwater, in shallow seas, or in freshwater areas with the goal of collecting bottom sediments and disposing of them in a different location. This method is frequently used to keep waterways navigable. It is also used to replenish sand on some public beaches that have lost sand due to coastal erosion. Fishing dredges are used to catch specific species of edible clams and crabs.

SAND

Sand is a granular material that occurs naturally and is made up of finely divided rock and mineral particles. It is distinguished by its particle size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or a soil type; for example, a sandy soil.

containing more than 85% sand-sized particles by mass.

Sand composition varies depending on local rock sources and conditions, but silica (silicon dioxide, or SiO2), usually in the form of quartz, is the most common constituent of sand in inland continental settings and non-tropical coastal settings. The second most common type of sand is calcium carbonate, such as aragonite, which was mostly formed by various forms of life, such as coral and shellfish, over the last half billion years. It is, for example, the primary type of sand visible in areas where reefs have dominated the ecosystem for millions of years, such as the Caribbean.

GRAVEL

Gravel is made up of unconsolidated rock fragments with a wide range of particle sizes and size classes.

From granules to boulders in size. The Udden-Wentworth scale divides gravel into two types: granular gravel (2 to 4 mm or 0.079 to 0.157 in) and pebble gravel (4 to 64 mm or 0.2 to 2.5 in). A cubic metre of gravel usually weighs around 1,800 kg (or a cubic yard weighs about 3,000 pounds).

Gravel is a significant commercial product with numerous applications. Many roads are surfaced with gravel, particularly in rural areas with little traffic. Globally, gravel roads outnumber concrete or tarmac roads; Russia alone has over 400,000 km (250,000 mi) of gravel roads. [1] Sand and small gravel are also important in the production of concrete.

1.8 ORGANIZATION OF THE STUDY

This research paper is divided into five chapters for easy comprehension.

The first chapter is concerned with the introduction, which includes the (overview of the study), problem statement, objectives of the study, research question, significance of the study, research methodology, definition of terms, and historical background of the study. The second chapter highlights the theoretical framework on which the study is based, as well as a review of related literature. The third chapter discusses the study’s research design and methodology. The fourth chapter focuses on data collection, analysis, and presentation of findings. The study’s summary, conclusion, and recommendations are presented in Chapter 5.