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Table 2 Variations of main scenarios with probability and consequence parameters

From: Using the multiple scenario approach for envisioning plausible futures in long-term planning and management of the urban water pipe systems

Main scenario Variations—consequence impact Scenario specifics Potential consequence Building blocks
1. Climate change a. Positive impact
b. Low negative impact
c. Medium negative impact
d. Major negative impact
Increase in precipitation intensity. - Capacity reduction in combined sewers (WW)
- More frequent basement flooding (WW)
- Generally increased hydraulic strain (WW)
Climate change
Frost and temperature patterns will change, including frosting and thawing cycles. - Increase in blockages of pipes and reduced reliability (WW)
- Reduced reliability (DW)
- Change in failure rates (DW)
Increased sedimentation and particle runoff to water sources (DW). - Sedimentation problems in pipes (DW)
Drought which causes ground movement due to lowered groundwater table - Increase in blockages of pipes and reduced reliability (WW)
- Reduced reliability (DW)
- Change in failure rates (DW)
2. Demographics Population change a. Low growth
b. Medium growth
c. High growth
d. Reduction
Increase in impervious areas and increased household wastewater discharge - Increased hydraulic strain on networks (WW) Demographics
Population growth - Need to increase hydraulic capacity (WW)
Increased water demand - Need to increase hydraulic capacity (DW)
- Change in water quality and reduced corrosion problems (DW)
Population reduction and water demand reduction - Water quality problems and increased corrosion (DW)
3. Delivered service a. As today
b. Higher in someareas
c. Higher in all areas
Stricter regulations (WW). - Less acceptance for pollution discharge (WW)
- Less acceptance for water leakages (DW)
- Less acceptance for failures (DW)
Governing and regulating aspects
Service level delivered to end users
Ambition of the water utilities
Public awareness - Less acceptance for basement flooding in residential housing (WW)
- Less acceptance for storm water flooding in urban areas (WW)
- Lower risk acceptance (WW/DW)
- Less acceptance for discoloured water (DW)
- Less acceptance for shut down of water supply (DW).
4. Technologic and methodical development a. As today
b. Higher efficiency and more green solutions
c. Higher efficiency, more green solutions, and more durable rehabilitation methods
More efficient and higher quality renovation methods - Simplifying rehabilitation and improving lifetime expectancy of renovated pipes (DW/WW) Technological and methodological development
Higher quality pipe materials - Improving lifetime expectancy of new pipes (DW/WW)
- Rehabilitation methods with longer life spans (like replacement) will be more environmental friendly which facilitates its use (WW/DW)
Higher share of green solutions in the rehabilitation market - Reduced hydraulic strain on pipes (WW)
Implementation of Low Impact Development (LID) solutions in storm water management - Facilitates a higher degree of rehabilitation rates due to reduced costs (WW/DW)
Higher degree of coordination between water, sewer and roads in rehabilitation - Facilitates a higher degree of use of replacement with longer life span than renovation methods (WW/DW)
5. Resource capacity a. Severely reduced capacity
b. Reduced capacity
c. As today
Higher capacity
Lack of personnel - Lag in rehabilitation (WW/DW) Economy
Organizational capacity
Lack of expert knowledge - Lag in rehabilitation and/or poorly managed and executed rehabilitation (WW/DW)
Insufficient financing in renewal - Lag in rehabilitation (WW/DW)
- Implementation of less than optimal, but low cost, solutions (WW/DW)
High inflation - Reduced capacity for investment in rehabilitation, which leads to lag in rehabilitation and/or implementation of less than optimal solutions (WW/DW)
  1. WW wastewater, DW drinking water