This document summarizes two case studies on innovative approaches to urban flood management. The first case study examines a sustainable rainwater utilization system implemented at Tianjin University in China. It describes how low impact development techniques like permeable pavement and constructed wetlands were used to infiltrate and treat rainwater, reducing flooding and pollution. The second case study models using small-scale hydropower systems in sustainable urban drainage systems in Lisbon to recover energy from stormwater runoff. It analyzes the potential power output for different pond sizes and turbine targets. Overall, the document outlines strategies for implementing "sponge cities" that can better absorb and use rainwater and stormwater.

1. INNOVATIVE APPROACHES TOWARDS URBAN
FLOOD MANAGEMENT
PRESENTED BY
APARNA A V
TCR19CEWR02
M2 WR & HI
1
GUIDED BY
PROF. SMITHA MOHAN K
PROFFESSOR
DEPARTMENT OF CIVIL
ENGINEERING

2. INTRODUCTION 2
URBAN FLOODING
• Inundation of land or property in a built environment.
• Occurs when rainfall overwhelming the capacity of
drainage systems.
• Creates Excessive runoff in developed areas.
• Urbanization leads to developed catchments therefore
flooding occurs very quickly.

3. URBAN FLOODING 3

4. MAJOR CAUSES OF URBAN FLOODING
• Meteorological Factor
• Hydrological Factors
• Human Factors
4

5. COMMON SOLUTIONS FOR URBAN FLOODING
• Create flood plains and overflow areas for rivers
• Separating rainwater from the sewer system
• Install water infiltration and attenuation systems
• Sustainable drainage: permeable pavement, sidewalks and gardens
• Green roofs/rooftop gardens
• Create sponge city.
5

6. SPONG CITY CONCEPT
• The Sponge City concept aims to
• (i) improve effective control of urban peak runoff, and to temporarily store, recycle and
purify stormwater;
• (ii) to upgrade the traditional drainage systems using more flood-resilient infrastructure
• (iii) to integrate natural water-bodies and encourage multi-functional objectives within
drainage design.
6

7. SUSTAINABLE URBAN DRAINAGE SYSTEMS (SUDS)
• The design of urban drainage mainly focuses on catching the excess runoff and lead it
out of the cities, according to sanitary and security precepts.
SUDS Management Train (CIRIA)
7

8. CASE STUDY: SUSTAINABLE RAINWATER UTILIZATION AND WATER
CIRCULATION MODEL FOR GREEN CAMPUS DESIGN AT TIANJIN UNIVERSITY.
• In unplanned urban expansion & increases in impervious urban land surfaces
traditional engineering infrastructures fails.
• This approach is also unable to cope with intense rainfall events, significant loss of
lives and economic impact due to flooding.
• Water pollution is another serious problem caused by increased urban population.
8

9. STUDY AREA
• Located in the Jinnan District of Tianjin, Tianjin University’s Peiyang Campus covers an area
of 2.5 million m2. The total water area of Peiyang Campus is 154,000 m2, including a
central lake, river, overflow lake, and constructed wetland.
Rainwater LID layout.
9

10. METHODOLOGY
• Construction Concept of Rainwater Discharging System
• Storing and infiltrating rainwater for underground water on one hand and rainwater use in
an artificial water body on the other hand.
Framework of rainwater circulation and discharge system.
10

11. 11
Rainwater LID layout

12. RAINWATER UTILIZATION SYSTEM AT THE CENTRAL
ISLAND RAINWATER ECO COLLECTION AREA
• The central island adopts LID practices including a vegetative swale, sunken green
space and permeable pavement to build a rainwater utilization demonstration area.
• The aim is to infiltrate and store rainwater, cut flood peaks, treat the rainwater, and
mitigate surface runoff pollution.
1) Sunken Green Space and Vegetative Swale
• Is a green LID technology
• Uses the recessed areas to store rainwater and dramatically lengthen the
rainwater infiltration time, thereby infiltrating and storing rainwater
• Elevation is lower than the road elevation.
12

13. 13
Sunken green space and vegetative swale on Peiyang Campus.

14. 2) Permeable Pavement
• Roads and sidewalks of the central island adopt a water-infiltration permeable pavement with
coverage of 85.8%, thus enabling rainwater infiltration.
• Central area boasts a slow traffic system and vehicle limitations.
• The central area is able to significantly cut 50% of rainwater runoff.
Permeable pavement on campus. (Source: Peng et al. ,2018)
14

15. WATER QUALITY CONSERVATION SYSTEM OF ARTIFICIAL
WATER BODIES
• Controlling pollutants and increasing water self-purification capacity and water circulation in
artificial water bodies.
• The integrated conservation measures of water quality are
• Pollutant-Control Measures
Done through a wastewater-treatment plant with the capacity of 1,000 m3/day.
• Ecological Revetment
The campus artificial water bodies embankments are natural revetments with water
plants, artificial riverbanks, and mixed revetments
• Aquatic Ecosystem
The complete aquatic ecosystem consists of aquatic plants, aquatic animals living at
different depths, and microorganisms that attach to the plants, aquatic animals, and silt
improve the water quality.
15

16. • Reoxygenation
• To facilitate circulation of the artificial water bodies and injection of oxygen into the
water.
• 34 reoxygenation machines set up around the central lake and waterfront area,11
installed at the overflow lake.
• Constructed Wetlands
• Wetlands achieve water purification through interactions among microorganisms,
plants, and other materials.
• The constructed wetland, lying to the west of the central lake, covers an area of 6,500
m2
16

17. RAINWATER UTILIZATION SYSTEM IN THE MIDDLE PIPELINE
RAINWATER COLLECTION AREA
• The rainwater in this area is collected by a pipeline.
• It supplements the artificial water body within the campus.
• Surplus rainwater is injected into the Weijin River through a pumping station.
Ecological revetment on Peiyang Campus.
17

18. RESULTS & DISCUSSION
BALANCE ANALYSIS OF AVAILABLE RAINWATER RUNOFF AND ARTIFICIAL WATER BODIES
SUPPLEMENTAL DEMAND
• Calculated the volume of rainwater, the rainfall volume on Peiyang Campus, Tianjin
University, was found to reach 621,500 m3
• Ground runoff and roofs are calculated as 80% of the rainfall volume
• River runoff is calculated as 60% of the rainfall volume, and greenbelt runoff is calculated
as 15% of the rainfall volume.
• The annual rainwater runoff for the central island rainwater eco collection area and middle
pipeline rainwater collection area of Peiyang campus is approximately 430,000 m3 before
adoption of the stormwater control measures.
• After introducing these measures, rainwater runoff dropped to an annual runoff of 328,152
m3
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19. CONCLUSIONS
• Rainwater runoff of the campus dropped significantly from 430,000 m3 to 328,152 m3
• The annual rainwater volume in the rainwater collection areas is larger than the water
loss of the artificial water bodies.
• Integrated measures increased the quality of water in the artificial water body.
• The water quality of the artificial water bodies is able to meet Level IV water quality
standards.
• More research is required to build a comprehensive computerized model for Sponge
City design.
19

20. CASE STUDY (2) : OPTIMIZATION OF ENERGY RECOVERY IN SUDS OF A SMALL
DISTRICT AREA OF LISBON THROUGH THE USE OF LOW-HEAD HYDROPOWER
CONVERTER.
• The flood-control and drainage systems can be seen as new hydropower
opportunities.
• The integration of hydropower production in SUDS will be sensitive to total runoff
• The combination of flood control with energy generation is the novelty proposal in
this research.
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21. STUDY AREA
• The studied area is a district of Lisbon located in a downtown area, near the Tagus
River and the Atlantic Ocean.
Example of flood events in Lisbon
21

22. SYSTEM MODELLING
• Mike Basin (MB) is a water management network model that analyses water resources
and water uses.
• It was created to solve water sharing problems and environmental issues in several
application fields.
• Rivers and channels are represented by branches on the system network and the nodes
represent confluences, diversions and water facilities such as reservoirs and hydropower
stations .
Simplified representation of a retention pond and hydropower-base system.
22

23. MODEL SIMULATION
MODEL CALIBRATION
• MB simulates the runoff on a catchment taking into account the hydrological cycle,
the type of soil and the provision of water, such as the over-land flow, base-flow and
inter-flow.
• The supply of water comes from rainfall and snow melt, being also affected by the
evaporation.
• The soil is divided into four inter-connected zones: surface, groundwater and snow
storage.
• Surface storage, interflow and base flows are considered negligible.
23

24. MODEL SIMULATION
• The pond at the starting point is considered dry.
• The rainfall is based on data belonging to the meteorological institute of Portugal,
from the station of Lisbon.
• Simulations are run for a series of daily rainfall.
• The objective is to analyse the electricity production capacity regarding the generated
power, the power deficit and the water turbine discharge.
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25. METHODOLOGY
• Identifying the influence of suitable microhydro converters on the generated power
solution and water discharge.
• According to each target demand, the height of the retention pond, the reduction
factor and the output data are defined as a function of the volume.
• The selected maximum heads are 3 and 10 m.
• The size of the area under analysis is set at 1 km².
• Rainfall and runoff graphs data are inputs to the model from the meteorological
station Lisbon.
• The feasibility analysis of producing energy with a micro-hydro converter is then
analysed.
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26. RESULTS & DISCUSSION
• This analysis is done by observing the evolution of the total generated power, total
power deficit and the flow discharged downstream as function of the pond volume.
Two selected power target demands for each hydropower station.
26

27. THE AVERAGE PER DAY OF THE TOTAL GENERATED POWER
FOR BOTH TARGETS IN A 10 M-HIGH POND
• Shows that the maximum generated power corresponds to the average per day of
the total target demand.
Average per day of generated power as function of the pond volume for two different targets and for a 10
m-high pond
27

28. AVERAGE PER DAY OF GENERATED POWER ANALYSIS FOR A
3 M-HIGH POND
• Shows that the maximum generated power corresponds to the average per day of the total
target demand.
• The flow has to be increased & the amount of water is not sufficient for the Target1.
• Target 2 is too low to be profitable and leads to important water losses as well
Average per day of generated power as function of the pond volume for two different targets and for a
28

29. IMPACT OF THE REDUCTION FACTOR
• Below a characteristic water level, called reduction level, the target demand is affected
by a reduction factor (RF) between 0 and 1.
• The generated power of 10 m-high pond is much higher than the one obtained with
the 3 m-high pond due to the low flow values It is more important.
• The reduction factor has a relevant influence on the optimization of the energy
production.
• The total generated power, the total power deficit and the directly discharged flow for
three different reduction factors (0.3, 0.5, and 0.8) for a 10 m-high pond with the Target
demand 1is drawn.
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30. • The reduction factor 0.5 leads to good production of energy, low power deficit (around 40%) when compared
with the reduction factor equal to 0.8.
• The directly discharged flow in the river decreases until 0 for volumes in which there is a better production.
Generated power as function of the pond volume for Power deficit as function of the pond volume for
different reduction factors. different reduction factors.
30

31. CONCLUSIONS
• The purpose of this study is to produce energy from a retention pond with a new microhydro
converter.
• The higher the water level in the pond for the same volume the better the production of
energy
• A special effort of optimization is required to maximize the generated power and minimize the
power deficit.
• The case study reveals that this system could produce about 210 MW h/year (for an average
year hourly power of 800 W).
• This new water-energy prototype can be implemented in existing runoff systems or in
forthcoming urban design solutions.
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32. REFERENCE 32
1. Ramos, H.M, Teyssier, Samora, I. and Schleiss, A.J. (2013). “Energy recovery in SUDS towards smart water grids:
A case study”. Journal of water resources planning and management, 62, pp.463-472.
2. Peng, S., Cui, H., and Ji, M. (2017). “Sustainable Rainwater Utilization and Water Circulation Model for Green
Campus Design at Tianjin University.” Journal of Sustainable Water in the Built Environment, ASCE, 4(1), pp. 1-
7.
3. Shunchan, F.K., Griffiths, J.A., and Higgitt, D. (2018): “Sponge City in China-A breakthrough of planning and
flood risk management in the urban context”. J. Land Use Policy, Elsevier. pp. 1-7.
4. Andoh, R.Y. and Iwugo, K.O., (2002): “Sustainable urban drainage systems: a UK perspective”.Global Solutions
for Urban Drainage, ASCE,123(5), pp.1-16.

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