Research article Evaluation of low impact development approach for mitigating flood inundation at a watershed scale in China Maochuan Hu a, * , Takahiro Sayama a , Xingqi Zhang b, ** , Kenji Tanaka a , Kaoru Takara a , Hong Yang c, d a Disaster Prevention Research Institute, Kyoto University, Uji, Kyoto, 611-0011, Japan b School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, Jiangsu, 210023, China c Norwegian Institute of Bioeconomy Research, Ås, 1431, Norway d CEES, Department of Biosciences, University of Oslo, Blindern, 0316 Oslo, Norway article info Article history: Received 1 September 2016 Received in revised form 9 February 2017 Accepted 11 February 2017 Available online xxx Keywords: Inundation depth Inundation area Hazard level Modeling Flo-2D model abstract Low impact development (LID) has attracted growing attention as an important approach for urban flood mitigation. Most studies evaluating LID performance for mitigating floods focus on the changes of peak flow and runoff volume. This paper assessed the performance of LID practices for mitigating flood inundation hazards as retrofitting technologies in an urbanized watershed in Nanjing, China. The find- ings indicate that LID practices are effective for flood inundation mitigation at the watershed scale, and especially for reducing inundated areas with a high flood hazard risk. Various scenarios of LID imple- mentation levels can reduce total inundated areas by 2%e17% and areas with a high flood hazard level by 6%e80%. Permeable pavement shows better performance than rainwater harvesting against mitigating urban waterlogging. The most efficient scenario is combined rainwater harvesting on rooftops with a cistern capacity of 78.5 mm and permeable pavement installed on 75% of non-busy roads and other impervious surfaces. Inundation modeling is an effective approach to obtaining the information neces- sary to guide decision-making for designing LID practices at watershed scales. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction The risk of extreme urban flooding/sewer flooding has been growing rapidly due to rapid urbanization and climate change, especially in low- and middle-income countries (IPCC, 2013). Minimizing the impact of urbanization and increasing urban resilience is an effective approach to reduce the urban flood risk as emphasized in the Sendai Framework for Disaster Risk Reduction (Kelman, 2015). Low impact development (LID), which is one of stormwater management strategies to preserve or replicate the pre-development natural hydrology of a site using a series of micro- scale control practices (Newcomer et al., 2014), was implemented in recent years to reduce the flood risk and increase urban resil- ience (Dietz, 2007; Todeschini et al., 2012). The benefits of LID practices on runoff reduction at individual sites have been demonstrated in a number of cases (Scholz and Grabowiecki, 2007; Ghisi et al., 2012; Berndtsson, 2010). For example, Shannak et al. (2014) reported that rainwater harvesting (RH) with an appro- priate cistern size reduced total runoff by 45% in a house with a virtual roof and lawn setup. Dreelin et al. (2006) reported that a permeable pavement (PP) parking lot can produce 93% less runoff than an asphalt parking lot. The performance of LID at watershed scale is substantially affected by their structures and properties (e.g., the percentage of the LID installation area and related drainage areas, Qin et al., 2013), and climate (e.g., rainfall duration and intensity, Gilroy and McCuen, 2009). Some recent studies have evaluated the effective- ness of LID implementation at watershed scale (Palla and Gnecco, 2015; Zhang and Hu, 2014), and several models (e.g. the Storm Water Management Model) have been developed to simulate the hydrologic impact of LID implementation (Elliott and Trowsdale, 2007; Baek et al., 2015; Trinh and Chui, 2013; Morsy et al., 2016; Duan et al., 2016; Chui et al., 2016). For example, LID imple- mentation in a high-density residential community in Nanjing, China, can reduce runoff by 0.6%e36.8% (Zhang et al., 2016). * Corresponding author. ** Corresponding author. E-mail addresses: hu.maochuan.4s@kyoto-u.ac.jp (M. Hu), zxqrh@nju.edu.cn (X. Zhang). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2017.02.020 0301-4797/© 2017 Elsevier Ltd. All rights reserved. Journal of Environmental Management xxx (2017) 1e9 Please cite this article in press as: Hu, M., et al., Evaluation of low impact development approach for mitigating flood inundation at a watershed scale in China, Journal of Environmental Management (2017), http://dx.doi.org/10.1016/j.jenvman.2017.02.020