The correlation of urban development and environmental impact – Mangroves Case Study

6th July 2023

The extent to which urbanisation has infiltrated the Earth’s natural space is immediately clear when we look at satellite imagery. 

When we compare historical imagery with recent captures it is clear to see how urban sprawl has progressed ever more rapidly, overtaking a dramatic amount of land. Only three decades into the past is long enough to see an impactful visual representation of human development. This trend has been occurring ever since humankind began to settle and exploded when towns became cities, and the population rose higher into the billions.  

Using satellite imagery, this increase can be quantified. Furthermore, techniques such as habitat mapping can accurately quantify the impact of urban expansion on the environment, species, and surrounding biodiversity.  

In this blog, we discuss how urbanisation impacts the environment using the example of mangrove forests. Mapping high-risk ecosystems and assessing the damage caused by developments is hugely important for monitoring impacts on biodiversity. 4EI’s net gain methods allow for sustainable development, helping engineers quantify construction impacts to mitigate net biodiversity loss. 

The decline of sensitive ecosystems

Mangroves are a clear example of how urbanisation and human activity have negatively impacted precious ecosystems, especially those that are already sensitive. Mangroves are a type of shrubbery that occur in tropical coastal conditions. They play an important role in maintaining many ecosystems, offering critical habitats to a range of species, protecting against extreme weather, and mitigating damage to the coastline. 

In a previous project, 4EI mapped all the mangroves within a region of the Middle East to assess the extent of urbanisation on these environments over three decades. Our team mapped three-time series using Landsat imagery (1987, 2001, 2017) and performed change detection between each dataset to quantify impact, represented by percentage change in size. We first calculated the square kilometre coverage of the mangroves for each time series and record the % change over time as shown below.  

The results showed a loss in mangrove coverage between 1987 and 2001, but then an increase between 2001 and 2017, and an overall increase from 1987 to 2017. With some mangroves placed in urban locations, it’s likely that this decline was partly due to direct urban impact. 

In addition, we considered the risk to mangroves associated with different locations. Mapping the mangroves in more detail – exploring key factors such as their proximity to urban areas, their proximity to habitats, and their level of fragmentation – gave us the intelligence to develop a risk indicator to categorise the mangrove locations.

This clearly mapped which mangroves were at greater risk of impact and supported the prioritisation of mangrove management or conservation, for example, proximity to an airport or polluting area, versus a sand dune would indicate higher risk.

High-risk habitats

This principle could apply to any habitat type, or general vegetation from sand sheets to trees. It could be particularly useful to identify and monitor high-risk habitats and the impact of high-risk urban infrastructure. For example, desalination plants will increase the salinity of the surrounding ocean area which has the potential to affect marine ecosystems such as mangroves and coral reefs. Similarly, urban activities, like the development of ports or city expansion, will impact marine vegetation and habitats.

Organisations can use satellite-derived habitat mapping to understand the impact on environments over time and identify which areas require targeted intervention to preserve, conserve, or rejuvenate.

The impact of damaging these environments

Ecosystems and the cycles that function within them are integral to many of Earth’s core functions. Changes and disruptions to biodiversity can therefore have far-reaching impacts on nature, people and the planet as a whole. The downstream impacts of urbanisation encroaching upon environments will therefore vary based on what habitats and species are affected and their role within wider ecosystems.

For example, mangrove decline can greatly influence carbon levels in the atmosphere. Mangroves are a prominent source for carbon sequestration, absorbing carbon dioxide which helps mitigate the impacts of climate change. When these environments are damaged or experience decline, there are two critical consequences. Not only is carbon dioxide released into the atmosphere, but there are then fewer sources for carbon sequestration which has long-term connotations for carbon levels and climate change.

This is an issue that is present across the globe. Satellite data can help to monitor the decline and our vegetation indices can be used to further map their health. Combined with an approximation of how much carbon mangroves can store, this data could be used to estimate carbon sequestration levels and model carbon offsetting activities. This allows organisations to mitigate their environmental impact during urban development projects and target their remediation actions.

A mentality shift in the industry

Awareness about these impacts is rising and it’s changing how people approach infrastructure and engineering development. Initially, measuring and mitigating biodiversity net loss was the primary concern for sustainable development. Now, organisations are taking on more ambitious visions. Prompted both by mentality shifts and a change in regulation, biodiversity net gain is now a key target for many urban development projects.

Satellite data can help organisations monitor both of these metrics – enabling decision-makers to be more informed about how they contribute to the environment during construction and to track their progress towards their goals.

4EI’s Biodiversity Net Gain method

4EI have access to extensive historical and up-to-date imagery archives that enable us to conduct a thorough environmental impact assessment.

First, we begin by mapping a development site prior to a project to establish a baseline. Within this, we will work closely with the client to create habitat categories that are tailored to your objectives. Then our team will use remote sensing capabilities to map and quantify the species, habitats and environments that are contained within the predetermined area.

The next stage involves mapping the same area again, using the same categories, at different points of time. This allows us to provide an accurate comparison of how habitat coverage has changed after development, delivered in a format which directly feeds into an organisation’s biodiversity net gain targets.

A future of sustainable engineering

The mentality shift we’re seeing isn’t just for show – sustainable engineering is being exemplified around the world.

From roof gardens in London to Ecotourism in Saudi Arabia, an increasing number of developments are putting environmental concerns at the fore. Some projects are additionally using green infrastructure to power the developments long-term, such as wind farms and solar farms. This is a radical shift, bringing sustainability into all elements of a development and ensuring the future-proofed existence of urban and natural environments.

Jonathan Hendry MSci, PMP®, MBA*

by Jonathan Hendry MSci, PMP®, MBA*

Jonathan provides Earth Observation and Remote Sensing repeated, consistent and transparent solutions. He is an expert in utilising Machine Learning, Deep Learning and NPL as part of 4EI AI solutions and analytics, to deliver evidence-based Global, National and even Local insights.

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