Fanhua Kong

Satellite-derived subsurface urban heat island.

The subsurface urban heat island (SubUHI) is one part of the overall UHI specifying the relative warmth of urban ground temperatures against the rural background. To combat the challenge on measuring extensive underground temperatures with in situ instruments, we utilized satellite-based moderate-resolution imaging spectroradiometer data to reconstruct the subsurface thermal field over the Beijing metropolis through a three-time-scale model. The results show the SubUHIs high spatial heterogeneity. Within the depths shallower than 0.5 m, the SubUHI dominates along the depth profiles and analyses imply the moments for the SubUHI intensity reaching first and second extremes during a diurnal temperature cycle are delayed about 3.25 and 1.97 h per 0.1 m, respectively. At depths shallower than 0.05 m in particular, there is a subsurface urban cool island (UCI) in spring daytime, mainly owing to the surface UCI that occurs in this period. At depths between 0.5 and 10 m, the time for the SubUHI intensity getting to its extremes during an annual temperature cycle is lagged 26.2 days per meter. Within these depths, the SubUHI prevails without exception, with an average intensity of 4.3 K, varying from 3.2 to 5.3 K.

Modeling stormwater management at the city district level in response to changes in land use and low impact development

Abstract Mitigating the impact of increasing impervious surfaces on stormwater runoff by low impact development (LID) is currently being widely promoted at site and local scales. In turn, the series of distributed LID implementations may produce cumulative effects and benefit stormwater management at larger, regional scales. However, the potential of multiple LID implementations to mitigate the broad-scale impacts of urban stormwater is not yet fully understood, particularly among different design strategies to reduce directly connected impervious areas (DCIA). In this study, the hydrological responses of stormwater runoff characteristics to four different land use conversion scenarios at the city scale were explored using GIS-based Stormwater Management Model (SWMM). Model simulation results confirmed the effectiveness of LID controls; however, they also indicated that even with the most beneficial scenarios hydrological performance of developed areas was still not yet up to the pre-development level, especially where there were pronounced changes from pervious to impervious land.

Assessing Growth Scenarios for Their Landscape Ecological Security Impact Using the SLEUTH Urban Growth Model

AbstractRapid urban population growth and the associated expansion of urban areas in China (as elsewhere) present significant environmental challenges and threaten urban and regional ecological security. Modeling land use changes is one way to aid the management of cities. Using remote sensing and geographic information system (GIS) software platforms, land use data for the years 1989, 1996, 2004, and 2010 for the area inside the Jinan third ring road were interpreted. An urban green space network was developed, as a core strategy to ensure landscape ecological security, and subjected to ecological sensitivity analysis. The green space network and the result of the ecological sensitivity analysis were integrated into the exclusion/attraction layer of an existing cellular automaton model: slope, land use, exclusion/attraction, urban extent, transportation, and hillshade (SLEUTH). A development scenario for land use change was constructed that integrates these landscape ecological security development (LESD...

Changes of Urban Green Spaces and Their Driving Forces: a Case Study of Jinan City, China

Urban green spaces are looked upon as the last remnant of nature in urbanized areas. They play a pivotal role in environmental and ecological changes, and furthermore can decide whether we can have a sustainable development in the urban area. With the urban growth, green spaces varied in the area, type and spatial pattern. To optimize urban green space in the future, it is necessary to understand the driving forces on the processes of urban green space changes. In this study we chose Jinan City as a case study. We analyzed the process of urban green spaces dynamic from 1996 to 2004. During this period, a significant increase of the total area of urban green spaces took place. However, the growth rate of different green space types was not the same. To better link the spatial pattern change with the process, a gradient analysis was conducted in 4 directions combined with landscape metrics. Based on the spatiotemporal change of urban green spaces, it could be concluded that urban greening policies and urban sprawl were the main driving forces.

Evaluation of the land-use suitability of Jinan City based on GIS and landscape metrics

Rapid urbanization processes have been primarily attributed to tremendous changes in the exploitation manner and intensity of urban land use. The limited and nonrenewable characteristics of urban land resources prompted to develop and utilize urban land use rationally, which would push the sustainable development of urban land use. The evaluation of urban land use suitability contributed to identify suitable sites and better develop as well as make full use of urban land resources, consequently, which drived the urban land use structure to achieve the optimal allocation. In this paper, taking Jinan City as an example, which introduced Analytical hierarchical analysis (AHP) and moving windows in combination with conversion matrices based on SPOT and ALOS high resolution remote sensing data, supported by ArcGIS integrated with Fragstats software platform. The research method embedded landscape metrics into AHP as assessment factors. Additonally, the weights of all evaluation factors were determined by Analytical hierarchical analysis. Ultimately, single factor assessment on all urban land use types was carried out, which made up of suitability layers to weighted overlay using GIS technology. At the same time, the paper made suitability evaluation and rating for urban land use status quo and analyzed the variable changes in urban land use suitability between different years combined with natural constrains and economic regulation elements, during the years from 1996 to 2009 in Jinan City. The results will be valuable to urban and regional planners to evaluate the existing urban policies and consequently develop appropriate responses or strategies for the urban sustainable development, and at the same time provide significant reference opinions about thoughtful arrangement of urban land sources.

Using GIS and moving window method in the urban land use spatial pattern analyzing

Urbanization is a major trend in recent years all around the word. Changes of land use due to urbanization is the main cause of urban natural recourses loss or fragmentation and consequently brings the worsening conditions of urban environment, as well as increase urban ecological problems. In this paper, the land use, especially the built-up land spatial pattern and changes, were monitored and quantified in the study periods 1989-2004 with GIS and moving window method. The application of moving window method could examine the land use change process and link pattern and process easily in the local area. The study shows a rapid increase in built-up land but mostly at the expense of green spaces and agriculture land. The changes of urban built-up land were not distributed evenly. In a general, the urban development of Jinan City is an irregular monocentric pattern. The orientation of urban development policy and the special topography were considered the major reasons. Besides, the attraction of green space amenity is also an important factor that can not be neglected. The results will be contributed to guide the urban land use planning and management, especially the urban natural resources conservation.