Climate Proof Cities

climate proof cities

A quarter of the planet will experience severe water shortages one month per year by 2030.

Cities ​are ​highly ​vulnerable to ​climatic risks. ​Think of heatwaves, water scarcity and extreme rainfall.

What can cities do to become resistant climate proof? Let’s give an overview.

Water scarcity in Cities

To become ​climate-ready, ​cities need to ​manage ​both ​demand for ​scarce water ​and extreme ​weather events. ​Demand ​management is ​the better use ​of existing ​water supplies ​before plans ​are made to ​further ​increase supply.​

Demand ​management ​promotes water ​conservation ​and efficiency ​through ​changes in ​practices, ​cultures and ​people’s ​attitudes ​towards ​water. In ​addition to ​balancing ​demand with ​supply, demand ​management ​enables water ​utilities to ​lower energy ​costs in ​providing water.​

Re-using rain and greywater

Only 20 % of water used by the sectors receiving a public water supply is actually consumed. The other 80 % is returned to the environment, primarily as treated wastewater. Concreted and sealed surfaces in cities typically direct the rainfall to the sewer networks where it is merged with wastewater. This prevents the rainfall from infiltrating the soil and forming part of our groundwater storage that can benefit us at a later date. Rain runoff and wastewater often pass through water treatment plants before being returned to rivers, usually far away from the cities. With some changes to urban water systems, both rain water and less polluted wastewater could be returned to the city’s water users.

One of these changes is the reuse of greywater. Read all about it.

Reducing loss

The loss of water through leakages can be considerable; in a lot of cities all over the world, more then 40 % of the total water supply is lost in the water transportation network.

Leakages can be prevented through maintenance and water network renewal, and also through the use of new technologies.

Such technologies may involve sensors that recognise and locate the noise from a leak or devices that use radio signals to detect the presence of flowing water. With the application of these technologies, public water systems no longer need to face the extra burden of water loss through leakages when fulfilling water demands with limited supplies. Read all about it here.

Green infrastructure

Meanwhile, ​green ​infrastructure ​is the use of ​natural or semi-​natural systems ​to manage ​stormwater at ​its source, ​keeping it away ​from the built ​environment ​while ​delivering ​multiple ​economic, ​social and ​environmental ​benefits such ​as reducing ​damage to ​property from ​localized ​flooding and ​reducing energy ​costs, and ​carbon ​emissions, of ​treating ​wastewater.​ Read all about it here.

Water Proof Cities

Integrated Resource Management Model

Water Demand Management

It is estimated that in the Water Services Sector water loss and inefficient usage could be as high as 45%. The Integrated Resource Planning process can determine at what rate and cost these inefficiencies can become an increased supply

Demand ​management ​promotes water ​conservation ​and efficiency ​– in ​times of both ​normal ​conditions and ​uncertainty ​– through ​changes in ​practices, ​cultures and ​people’s ​attitudes ​towards ​water. In ​addition to ​balancing ​demand with ​supply, demand ​management ​enables water ​utilities to ​lower energy ​costs in ​providing water.​​

Instead, it ​can involve ​simple actions ​that enable ​households to ​reduce their ​water ​consumption and ​lower the ​amount of ​runoff from ​their ​properties into ​the stormwater ​system. Two ​examples of ​which are South ​West Water’​s free water-​fixtures ​program and New ​York City’​s free rain ​barrel program.​

So the scope of a city includes both distribution management and customer or end use Demand Management measures.

How is Integrated Resource Management (IRP) different from traditional planning?

It is wrong to regard IRP as something completely new or as the “same old thing” from what many water institutions are currently doing. The are four differences of IRP from the current planning practises that are worth identifying:

  1. Integration of planning to achieve the best results to society (end consumer).
    Current planning practises focus on the best-perceived solution from the institution perspective
  2. Evaluation criteria must be comprehensive and include social, economic, and environmental
  3. Water demand-side management measures are considered as an alternative resource option and not a separate campaign
  4. Evaluation criteria must be looked at from the life cycle of the different measures and not just on implementation

Evaluation criteria in an IRP process

The are six key evaluation criteria that should be considered in the evaluation process to determine the best combination of demand-side and supply-side management measures:

  1. Environmental impact
    The environmental index is a composite of four types of environmental impacts. These are Wetlands, Scenic resources, endangered species, and environmental water reserve.
  2. Social impact
    The social impact index is a composite of five types of social impact. These are affordability, job creation, sustainability of services, public acceptability, and service delivery to new consumers.
  3. Risk
    Risk is measured in terms of forecasting uncertainties. An index that indicates the uncertainty of a specific measure to supply or make water available must be determined for each option.
  4. Technical feasibility
    The technical index is a composite of four types of technical criteria. Time constraints, availability of appropriate technology, availability of capacity to implement and overall practicality to implement.
  5. Economic (Cost)
    IRP can only be achieved through the ethos of partnerships and customer focus.
    The economic criteria and financial evaluation considerations are described in more detail in the section below.

Participating Customer Test

The net present value (NPV) from the participating customer perspective (PCT) is given by:

PCT = RB – CC

  • RB = PV of all benefits to all participating customers from reduced bills;
  • CC = PV of customer costs (all net costs excluding rebates, incurred by all participating customers)
  • PV means the present value of the stream of costs and benefits over time

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