Wuhan, the central city in the middle reach of the Yangtze River of China, is famous for its lake resources. However, the city's lake area decreased by 37.4% from 1991 to 2005. This study aims to analyze the relationships between lake area reduction and lakefront land use changes in Wuhan. In this paper, the connections between the spatial changes of lake areal extent and land use changes in the lakefront were established with mathematical models such as Moran's I and spatial analysis models such as transition matrix. Regarding the impacts of lakefront land use changes on lake area in the urban and suburban districts of Wuhan City, it can be concluded that: (1) the loss rate of lake area would be increased if the proportions of lakefront land use changes transformed into developed or agricultural land from other land use categories became higher; (2) the higher spatial autocorrelation of lakefront land use classifications (Moran's I > 0.25) could be an indicator for the loss rate of lake area in urban district of the city; and (3) the vector sum of lakefront land use changes was related to the displacement of lake center.

This paper proposes a new rapid simplified inundation model (NRSIM) for flood inundation caused by rainstorms in an urban setting that can simulate the urban rainstorm inundation extent and depth in a data-scarce area. Drainage basins delineated from a floodplain map according to the distribution of the inundation sources serve as the calculation cells of NRSIM. To reduce data requirements and computational costs of the model, the internal topography of each calculation cell is simplified to a circular cone, and a mass conservation equation based on a volume spreading algorithm is established to simulate the interior water filling process. Moreover, an improved D8 algorithm is outlined for the simulation of water spilling between different cells. The performance of NRSIM is evaluated by comparing the simulated results with those from a traditional rapid flood spreading model (TRFSM) for various resolutions of digital elevation model (DEM) data. The results are as follows: (1) given high-resolution DEM data input, the TRFSM model has better performance in terms of precision than NRSIM; (2) the results from TRFSM are seriously affected by the decrease in DEM data resolution, whereas those from NRSIM are not; and (3) NRSIM always requires less computational time than TRFSM. Apparently, compared with the complex hydrodynamic or traditional rapid flood spreading model, NRSIM has much better applicability and cost-efficiency in real-time urban inundation forecasting for data-sparse areas.

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Urban lakes have been threatened by rapid expansion of cities in recent years. Their area changes could be extracted by remote sensing technologies. On this basis, a Dynamic Urban Lake Area Evolution Model (DULAEM) is proposed based on a multiagent system (MAS) and a cellular automata (CA) model. The DULAEM is integrated upon an Urban Lake Multilevel Grid (ULMG), which is composed of the vector model with the raster model. In the DULAEM, the CA layer is mainly used for modelling the interactions between urban lakes and their surrounding land use change through the activity of each cell; the MAS layer represents the actions of three typical human activities: government, real estate developers, and residents. These three agents have different actions in extent, strength, and priority according to their standpoints and functions. The CA layer and the MAS layer are both integrated upon the ULMG. Finally, a case study in Wuhan proves that the DULAEM can control the global relative error under 10%. Therefore, the DULAEM is able to simulate the area change of urban lakes dynamically. It is significant for the policy-making of lake protection and the optimal configuration of land resources in the lakeside.