Intoduction
Urbanization leads to developed catchments, which in turn increases the flood peaks by 1.8 to 8 times
and flood volumes by nearly 6 times.
(Zimmermann, Bracalenti, Piacentini, & Inostroza, 2016) presents the study that showcase the
risk of flooding in urban area in relation to land use change and impacts of runoff. Implementation
of GI and green areas in urban settings dictate an important strategy of adaptation to climate
change and urban land use change. With the increasing trends of urbanization and population
growth, implication of green spaces has proved to prevent increase in flooding in the future.
(Schubert, Burns, Fletcher, & Sanders, 2017) studied the benefits of implemented GI on
reducing the flood hazards under different rainfall patterns and especially short duration storm
events. GI reduces considerable amount of peak discharge and total flow volume which led to
reduction in flood impacts which is clearly depicted by the metrics used in a coupled hydrologichydraulic modelling of the study. (MUSIC, BreZO)
(Yin et al., 2020) compared the simulation results of SWMM and CADDIES 2D with the results of
MIKE FLOOD and found out that the integrated SWMM-CADDIES model was more efficient while
conducting small-scale simulations. The accuracy with SWMM simulation is higher for small
community scale simulations whereas for a larger watershed with complex catchment
characteristics ,MIKE URBAN model could deliver higher accuracy.
(Li, Liu, Engel, Chen, & Sun, 2019) explored the implementation effects of various GI practices
using a simulation model for water quantity and quality management under different land use
impacts. Estimation of runoff volume is considered an important factor to assess the effects of GI
practices for storm water management which eventually contributes to water quality and quantity
management in a watershed.
(Kim & Park, 2016) studied the impact of different metrics of landscape that influences the peak
runoff of an area .The size of the landscape greatly impacts the peak runoff and therefore it is
essential to incorporate various patterns of landscape while GI plans for attenuating local flooding.
Peak runoff can be influenced by shape and size of landscape patterns which signifies the need
for innovative application of flood mitigation strategies in the areas with high urban development.
Also Strategic land use should be considered.
(Dong et al., 2020) performed a city scale study in Xiamen on impact of a green strategy i.e. green
roof space to determine its benefits on maintaining the thermal environment in a high density urban
area. The study showed some significant impacts of green roofs installed on reducing urban heat
island effect as one of the noteable benefits of green infrastructure in Xiamen city in the face of
land shortages in a highly urbanized area.
(Liu, Ahiablame, Bralts, & Engel, 2015) applied a simple model L-THIA-LID which uses curve
number method to calculate average annual runoff especially to determine the impacts of land use
and LID practices on hydrology. The performances of different LIDs and BMP practices were
determined under different land use units, which points out these solutions could be applied to
reduce the increasing impacts of urbanization. The successful simulations of reduction in runoff
volume with these practices indicates the applicability of the model in planning and decision making
to evaluate their hydrological performance.
(Jiang, Zevenbergen, & Ma, 2018) addressed the water related challenges faced by China which
is enhanced by extensive urbanisation and climate change with the adoption of a policy initiative
known as sponge cities in 16 chinese cities. The national initiative of alleviating urban flooding and
associated risk due to increasing urbanisation and improper drainage system, is a holistic nature
based approach which is planned to achieve over a period of 2014 to 2020. (MHURD, 2014) This
innovative approach utilizes nature based solutions in urban settings to store and detain water and
manage storm water without disturbing natural hydrological process (MHURD, 2014).
To alleviate the risk of urban flooding and address the water issues aroused due to urban
development in CHINA, green infrastructure and nature based technologies could be a potential
and promising solutions that has to be incorporated in urban planning and design. (Jiang,
Zevenbergen, & Ma, 2018)
(Webber et al., 2019) Analysed the performance of retrofitted GI interventions in reducing the
flood depth. Peak flood depth is used as a major metric for the analysis of flood hazard that can
be useful in decision support. Many studies suggest that it is important to implement GI in large
scale catchment area to achieve substantial reduction of flood risk with involvement of catchment
stakeholders for developing strategic interventions for effective flood mitigation and benefits in
catchment scale.
CADDIES as it is a rapid model which enables relatively accurate simulation of rainfall-runoff and
flooding on the surface, while enabling a computationally efficient process
Rainfall runoff model
US EPA model SWMM is an open source, dynamic rainfall runoff model for simulating
hydrological processes and storm water management. The simulation model can be used for
single rainfall/storm events or continuous or long term events especially in urban
areas.(Rossman, 2010)
Studies in Xiamen
The understanding of hydrological process and simulation of the hydrologic reponses of a
catchment is crucial for identifying the performance and effectiveness of GI.This is fundamental
in identifying the most suitable adaptive strategies for GI to attenuate flooding.
OBJECTIVES
Runoff estimation of a catchment
SCS CN method: The SCS-CN method was introduced by the Soil Conservation Service (SCS)
of the United States Department of Agriculture (USDA) in 1954 and defined by National
Engineering Handbook (NEH-4) section of Hydrology (Ponce and Hawkins, 1996). The Curve
Number (CN) method is a well-known hydrological model for the estimation of surface runoff.
Calibration and validation of model
Dong, J., Lin, M., Zuo, J., Lin, T., Liu, J., Sun, C., & Luo, J. (2020). Quantitative study on the cooling
effect of green roofs in a high-density urban Area—A case study of Xiamen, China. %J Journal
of Cleaner Production, 255, 120152.
Jiang, Y., Zevenbergen, C., & Ma, Y. (2018). Urban pluvial flooding and stormwater management: A
contemporary review of China’s challenges and “sponge cities” strategy. %J Environmental
science
policy, 80, 132-143.
Kim, H. W., & Park, Y. (2016). Urban green infrastructure and local flooding: The impact of landscape
patterns on peak runoff in four Texas MSAs. Applied Geography, 77, 72-81.
doi:https://doi.org/10.1016/j.apgeog.2016.10.008
Li, F. Z., Liu, Y. Z., Engel, B. A., Chen, J. Q., & Sun, H. (2019). Green infrastructure practices simulation
of the impacts of land use on surface runoff: Case study in Ecorse River watershed,
Michigan. Journal of Environmental Management, 233, 603-611.
doi:10.1016/j.jenvman.2018.12.078
Liu, Y., Ahiablame, L. M., Bralts, V. F., & Engel, B. A. (2015). Enhancing a rainfall-runoff model to
assess the impacts of BMPs and LID practices on storm runoff. Journal of Environmental
Management, 147, 12-23. doi:https://doi.org/10.1016/j.jenvman.2014.09.005
Rossman, L. A. (2010). Storm water management model user's manual, version 5.0: National Risk
Management Research Laboratory, Office of Research and ….
Schubert, J. E., Burns, M. J., Fletcher, T. D., & Sanders, B. F. (2017). A framework for the case-specific
assessment of Green Infrastructure in mitigating urban flood hazards. Advances in Water
Resources, 108, 55-68. doi:10.1016/j.advwatres.2017.07.009
Webber, J., Fletcher, T., Cunningham, L., Fu, G., Butler, D., & Burns, M. (2019). Is green infrastructure
a viable strategy for managing urban surface water flooding? %J Urban Water Journal, 1-11.
Yin, D., Evans, B., Wang, Q., Chen, Z., Jia, H., Chen, A. S., . . . Leng, L. (2020). Integrated 1D and 2D
model for better assessing runoff quantity control of low impact development facilities on
community scale. Sci Total Environ, 720, 137630. doi:10.1016/j.scitotenv.2020.137630
Zimmermann, E., Bracalenti, L., Piacentini, R., & Inostroza, L. (2016). Urban Flood Risk Reduction by
Increasing Green Areas For Adaptation To Climate Change. World Multidisciplinary Civil
Engineering-Architecture-Urban Planning Symposium 2016, Wmcaus 2016, 161, 2241-2246.
doi:10.1016/j.proeng.2016.08.822