## 5 Discussion  
To quantitatively analyze the potential risk caused by subsidence in the land use planning, we combined subsidence monitoring results with twenty-two land use types according to future land use planning (XXNA was divided into 5 different land use types). According to four subsidence rate classes and the Expectation and Entropy methods, we calculated the area and the values of Ex and En in different land use types. The statistical results are shown in Table 2. We divided different land use types of Dadeng Island into four risk classes by subsidence rate to show the spatial distribution of potential risk caused by subsidence on Dadeng Island (Figure 11a). High risk areas, accounting for about 3.87% of the total land area (Figure 11b), are mainly distributed in Land for Airport, Road, Retail Commercial Land, Apron, Green Space and Square Land, Class I and II Residential Land, and Commercial and Financial Land (see Table 2). Moderate risk areas account for 2.42% of all and mainly in Land for Airport, Road, Green Space and Square Land, and Class I and II Residential Land (see Table 2). Low risk areas and Very Low risk areas represent about 8.32% and 85.39%, which means that most areas of Dadeng Island are stable and suitable for future land use. As the areas of different land use types have significantly different subsidence rate, Figure 12 presents the percentage of potential risk in different land use types. From the results, we can clearly see that the potential risk in Special Land is highest, which has 13% high risk and 26% moderate risk. Then there is Sports Land, which has 13% high risk and 17% moderate risk. In addition, the high risk areas in Commercial and Financial Land, Apron, and Retail Commercial Land are more than 5%. For these land use types, subsidence would have significant influence to the future land use and the potential subsidence risk should be considered. In contrast, the land use types of Other Public Management and Public Service Facilities and Class III Residential Land have very low risk, which are suitable for future land use. For XXNA, the highest potential risk is in Apron and Airport Infrastructure, which have 8% high risk and 4% moderate risk, and 5% high risk and 7% moderate risk, respectively. The moderate potential risk is in Land for Airport and Runway, which have 3% high risk and 2% moderate risk, and 2% high risk and 3% moderate risk, respectively. The lowest potential risk is in Terminal, which only has 6% low risk and 94% very low risk. Therefore, attention has to be paid to  
Figure 10: Annual subsidence in Dengqi (Region C in Figure 6a). Figure 13 presents Expectation (Ex) and Entropy (En) values in different land use types. As mentioned in Section 3.2, Ex and En values can be used to analyze the overall level and the degree of non-uniformity land subsidence in terms of different land use. The results show significant difference of potential risk. Some land use types, such as Special Land and Sports Land, have high Ex values (more than -30) and high En values (more than 20). It means that the subsidence magnitude and the non-uniformity degree of subsidence are large in these areas. While for some other land use types, such as Regional Transportation Facilities Land, have low Ex values (Ex value below 5) and moderate En values (more than 9), i.e., the subsidence magnitude is low, but the non-uniform degree is large. The non-uniform subsidence is the most serious problem in these areas. Other Public Management and Public Service Facilities and Class III Residential Land have low values in Ex and En (Ex value below 5 and En value below 3). These areas are quite stable and have no potential subsidence risk. Therefore, the overall level and the non-uniformity degree of land subsidence in different land use types are determined by Ex and En methods, which provide a qualitative reference for prevention and control of subsidence geohazard. Figure 12: The percentage of potential risk in different land use types.