13. Water in urban environments

Duration: 3 sessions of 45 minutes

Managing water in cities is a complex task that requires careful planning, investment in infrastructure and sustainable practices. By adopting effective water management strategies and promoting responsible water use, cities can ensure a reliable water supply for their residents while minimizing their impact on the environment.

Introduction / Background

Water is a precious resource that goes through a continuous cycle of evaporation, precipitation, and return to the oceans. However, this process is not always simple, especially at the local level. Sometimes water falls on an area, accumulates, and causes flooding, or can run off quickly, leading to water shortages. That is why it is crucial to manage water resources efficiently and sustainably. By keeping water in our systems as long as possible, we can use it more than once, reduce water wastage, and even prevent flooding.

In urban areas, water is crucial for drinking, sanitation, and industrial processes. However, managing water in cities can be difficult due to limited water sources and high population density. Important factors related to urban water management include water supply, demand, infrastructure, wastewater and stormwater management, water conservation, and water management. By implementing effective water management strategies and encouraging responsible water usage, cities can guarantee a steady water supply for their residents while minimizing their environmental impact.

Several water conservation methods can be implemented in urban areas to promote sustainable water usage. Some of these methods include:

Efficient irrigation systems: Installing drip irrigation or using sprinkler systems with smart controllers can help reduce water wastage by delivering water directly to plant roots and adjusting watering schedules based on weather conditions.
Rainwater harvesting: Collecting rainwater from roofs and storing it in tanks or underground reservoirs can provide an additional source of water for gardening, washing cars, or flushing toilets.
Greywater recycling: Treating and reusing greywater from sources such as sinks, showers and washing machines for purposes such as irrigation or toilet flushing can significantly reduce the demand for fresh water.
Water efficient devices: Installing low-flow faucets, showers and toilets can help reduce water consumption without compromising functionality.
Public awareness and education: Promoting water conservation practices through public campaigns and educational programs can raise awareness of the importance of water conservation and encourage responsible water use.
Detection and repair of leaks: Regular inspection and repair of leaks in water supply systems, in households and public infrastructure, can prevent unnecessary water loss.
Xeriscaping : Landscape design with native plants that require less water can reduce the need for irrigation in urban areas.
Water metering and pricing: Implementation of water metering systems and various pricing models can promote water conservation by increasing users’ awareness of their water usage and encouraging efficient use.

Water pollution poses a significant problem for urban areas. Phytoremediation, which involves using plants to purify water, is a natural and environmentally friendly solution. Certain plants can absorb, break down, or transform contaminants in water. Here are some commonly used plant-based water purification techniques:

Wetlands or Constructed Wetland Systems: Wetlands are natural water filtration systems that use plants, soil, and microorganisms to remove pollutants. Constructed wetlands mimic this process and can be designed to treat specific pollutants. Plants such as rushes, reeds and sedges help filter pollutants as soil microorganisms break them down.
Aquatic plants: Some aquatic plants, such as water hyacinths and water lentils, can absorb and accumulate pollutants such as heavy metals and organic compounds. These plants can be grown in bodies of water to help purify the water by absorbing pollutants.
Biofilters: Biofilters use plants and their root systems to filter water. The water passes through a container filled with plant roots that trap and break down pollutants. This method is commonly used in aquariums to maintain water quality.
Algae-based systems: Algae can remove nutrients such as nitrogen and phosphorus from the water, which can cause water pollution. Algae ponds or bioreactors can be used to grow algae and remove these nutrients from wastewater or polluted water sources.

The use of plants in urban environments can play a significant role in flood prevention by controlling stormwater. Here are some ways plants can be useful:

Green infrastructure: Green infrastructure involves using techniques such as green roofs, rain gardens, and bio-lights to absorb and retain rainwater. These features consist of vegetation and permeable surfaces that enable water to soak into the soil, which helps reduce the amount of runoff and slow down its flow.
Planting trees: Trees have extensive root systems that can absorb significant amounts of water. Planting trees in urban areas helps increase soil permeability and reduces surface runoff. In addition, trees provide shade, which can lower the ambient temperature and reduce the risk of intense rainfall.
Riparian Protectors: Creating a vegetative buffer along rivers, streams, and other water bodies can mitigate flooding by stabilizing banks, absorbing excess water during heavy rainfall, and filtering out pollutants to improve water quality.
Green spaces and parks: The creation and preservation of green spaces within cities, such as parks and urban forests, can act as natural rain sponges. They help water to seep into the soil, thereby reducing both runoff and the likelihood of flooding.
Sustainable Urban Drainage Systems (SUDS): SUDS are designed to mimic natural drainage processes by incorporating vegetation, permeable surfaces and storage features. They help manage stormwater runoff by slowing its flow, promoting infiltration, and reducing the burden on traditional drainage systems.

When implementing these measures, it is important to take into account the specifics and requirements of each city. Local climate, soil conditions and urban design should be considered to maximize the effectiveness of plant-based treatment and flood prevention strategies.

We can all contribute to conserving and managing water resources. This can be done by adopting simple habits such as reducing water use, promptly fixing leaks, using water-efficient appliances and equipment, employing responsible irrigation techniques, and being mindful of water use in everyday activities like showering and washing dishes.

Additionally, supporting initiatives and policies that promote sustainable water management can further enhance our conservation efforts.

In conclusion, it is crucial to preserve and safeguard water as it is a precious resource. Responsible management and understanding of its cycle provide us with sufficient water for our future needs and generations.

Goal

The aim is to assist students in comprehending the challenges and strategies involved in the management of water resources in urban areas. The objective is to educate them about the significant role of sustainable water management methods and their impacts on urban communities and the environment. By doing so, students will gain a deeper appreciation for the significance of efficient water management in densely populated areas and the vital need for sustainable practices.

Step by step/ How to

Water in the landscape – an experiment

Prepare two plastic sheets. Leave one panel blank.
Cover the second panel with several layers of textiles to simulate the layers of the earth.
Use different objects and materials (textiles, plastic straws, sponges, toothpicks) to create models of drywall, trees, lakes, bushes, etc., and place them on the board.
After preparing the plates, instruct the students to pour the same amount of water on both plates.
Observe and note what happens to the water.

Discuss with the students the results of the experiment and the importance of healthy soil and water retention barriers.

Reflection questions

How can we contribute to water management in urban areas?
What specific actions can be taken to promote water conservation in urban areas?
How can we raise citizens' awareness of the importance of water management and conservation?
What steps have we taken to reduce water consumption in our own homes or schools?
Are there innovative technologies or practices that can be applied to optimize water use in urban areas?
How can we engage with the community to encourage their participation in water conservation practices?

Learning objectives

Identifying water-related challenges in urban areas: This includes discussing specific water-related problems facing cities, such as water scarcity, pollution, aging infrastructure and increased demand due to population growth.
Research on sustainable water management strategies: This involves introducing different approaches to solving the problem, including water conservation, rainwater harvesting, wastewater treatment and reuse, green infrastructure and efficient water distribution systems.
Promoting responsible water usage: The objective is to encourage students to develop water-saving habits, such as reducing water consumption, fixing malfunctions, and using water-efficient appliances and equipment.
Consideration of social and environmental impacts: This involves discussing the impact of water management decisions on public health, ecosystems, and the overall sustainability of urban areas.