Index Introduction Problem definition Objective and research question Introduction Flooding is one of the major and most frequent natural disasters in the world (Jiang et al., 2006). As revealed by the World Meteorological Organization (WMO, 2014), storms and floods accounted for 79% of the total number of disasters that occurred between 1970 and 2012, causing 54% of deaths and 84% of economic losses. It is found by many researchers (IPCC, 2014; Saghafian et al., 2010; Jiang et al., 2006; Li, 2011) that flood events have been increasingly frequent and show a trend of greater damage in recent decades. Global issues, such as climate change, population growth and deterioration of ecosystem services, may further contribute to increased flood risk (WMO, 2018). China is rich in water resources, having considerable rivers with a total length of 42,000 km. Meanwhile, China is also one of the most flood-affected countries in the world in terms of both the number of deaths and economic losses. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get Original Essay The map (Figure 1) provided by WMO (2014) illustrates that China lost more than $100 billion due to disasters in the period from 1970 to 2012, mainly due to floods. With the increasing impact of human intervention and climate change, the diversity of flood risks, such as a higher risk of dam failure, is defined as new characteristics of flood risk (Wan and Wang, 2011). Its length is 1,000 km and the basin area is 270,000 km2 with 170 million inhabitants and 12 million hectares of cultivated land in total, ranking third among all Chinese basins. Annual runoff and precipitation in the Huai River are recorded as 62.2 billion m3 (Gebeyehu et al., 2018) and 875 mm, respectively. Precipitation also shows an uneven distribution which is concentrated in the July-September period (70%) and decreases from the southern areas (1400-1600 mm) to the northern areas (600-700 mm) (Qian et al., 2017). Due to these characteristics, the Huai River is constantly subject to flooding. For example, from 1994 to 2007 floods occurred ten times (Gebeyehu et al., 2018). Furthermore, Jun et al. (2012) found that water resources in the Huai River are quite sensitive to climate change. Therefore, water management in the Huai River is facing not only problems related to the current situation but also future challenges. Problem Definition As mentioned above, many natural disasters, especially flood events, often occur in the Huai River Basin. To address flood and drought problems, the Chinese government has built a large amount of water projects along the Huai River, such as locks and dams, as well as projects with non-structural measures. Among the structural measures, management of storage areas can effectively alleviate the flood situation by storing water in them so as to protect important downstream cities. However, the interests of residents living in the storage areas would be harmed, as they use the areas for housing and agricultural activities. Apparently, protecting downstream areas/cities and minimizing flooding in storage areas are two conflicting goals. Therefore, there is a significant and urgent need to develop effective and reliable improvement of storage area operations to reduce flood damage in flood-prone areas. Some optimal strategies for the middle part of the Huai River?