Categories: Business

Reducing urban city flood disasters through restoration of degraded forests

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3 years ago

Urban cities have been suffering from increasingly severe flooding events, which destroy infrastructures, disrupt economic activities, and have several social impacts, including the loss of human lives. Globally, the highest frequency of floods occurred in 2006, with 226 reported cases, and their greater economic impact in 2011, with $70.76 billion in damages. These impacts are expected to continually rise in frequency and intensity due to urbanization, population increase, economic growth, and climate change.

Urban forestry is the care and management of single trees and tree populations in urban settings to improve the urban environment. The urban forest ecosystem is a collection of living organic matter (plants, animals, people, insects, microbes, etc.) and dead organic matter (lawn clippings, leaf-fall, branches) on a soil through which there is a cycling of chemicals and water and flow of energy.

Urban forests reduce energy costs, improve mental well-being, increased home values, and incomes, store carbon, and most importantly decrease runoff.

Trees significantly reduce runoff by taking up water through their roots. Runoff from an area covered in an impervious surface is five times that of a forested watershed of the same size.

Reduced runoff leads to improved water quality, as it reduces the amount of polluted runoff that enters our waterways. Urban forests also reduce the risk of flooding and promote the restoration of groundwater. According to i-Tree, Raleigh’s urban forest saves $4.5 million each year in avoided runoff-related costs.

Vegetation increases evapotranspiration, rainwater interception, and water infiltra[1]tion while decreasing peak discharge, runoff speed, and the frequency of floods in general.

Thus, the urban forest is indispensable to environmental management and to achiev[1]ing sustainable cities. The urban forest comprises a wide range of vegetation types present in the city, such as street trees, gardens, landscaped boulevards, public squares, parks, native vegetation remnants, and riparian corridors.

This vegetation generates many essential ecosystem services, such as well-being and health, air quality, climate regulation, nutrient cycling, and erosion and flood control.

Despite the importance of these remaining vegetation patches within urban areas, many of these patches are of low quality. One cause for the low quality is that during construction more land is cleared than is used, and these areas, which have been degraded, are often colonized by grasses.

The most common pressures causing urban deforestation and severe degradation are agriculture, unsustainable forest management, mining, infrastructure projects, and increased fire incidence and intensity. Some infrastructure projects, like creating roads, have a significant indirect impact by allowing people and farmers access to forests.

Significant forest damage results from overharvesting trees for domestic use or the com[1]mercial trade in fuelwood and charcoal.

Urban city forests and freshwater ecosystems are put under additional stress by mining projects, which usually coincide with the construction of significant infrastructures like roads, railway lines, and power plants.

Some landowners and producers are further encouraged to clear forests within cities by poorly executed environmental rules.

Soil erosion commonly appears after the conversion of forests to agricultural land, sweeping away fertile soil and pesticides. When forests are cut down, the exposed topsoil frequently starts to erode, increasing the amount of sediment entering waterways (for example, rivers).

The situation worsens if there are no longer any forests or trees along the sides of rivers to store the soil brought by rain.

Restoring these identified degraded areas with trees is the key to reducing urban floods. Restoration is the process of assisting the recovery and management of ecological integrity. Ecological restoration aims to return a system to its historical trajectory toward resilience and the ability to recover from disturbance.

For urban forests to be restored and sustainable, there must be a shift to an integrated participatory management approach that engages members of the community in plan[1]ning, designing, establishing, and maintaining the forests.

The people should be enlightened on the importance of forests in urban centres. Increasing public awareness of the importance of urban forestry is an important factor to consider for its long-term sustainability. Areas prone to flood are to be considered for resto[1]ration.

Decision makers are to be proactive to reduce disaster risk and assist cities in adapting to increasing climate change impacts.

Dr Tayo Oyelowo is an expert in Forest Ecology and Conservation

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