Refining Urban Built-Up Area via Multi-Source Data Fusion for the Analysis of Dongting Lake Eco-Economic Zone Spatiotemporal Expansion

Qianming Li,Wei Jiang,Bohong Zheng,Bing Tu,Kai Yao,Zhiyuan Wang,Jiawei Yang,Yusheng Yang

doi:10.3390/rs12111797

Abstract

Rapid urbanization has given rise to serious urban problems. It is crucial to understand the urbanization process to accurately and quickly identify boundary changes in urban built-up areas and implement planning schemes and adjustments in scientific and effective ways. This study proposes a new method to automate and refine the extraction of urban built-up areas by using Landsat and nighttime light (NTL) imagery. The urban agglomeration of Dongting Lake Ecological Economic Zone (UADLEEZ) Landsat data are mapped to NTL data using resampling, superpixel segmentation, and assigning the blank part with the Euclidean distance method. We then compared our findings with those produced via traditional threshold extraction methods. In total, 33 built-up areas of UADLEEZ boundary maps were produced between 1992 and 2018. Thus, we reached the following conclusions: (1) the urban built-up areas obtained via our proposed method are finer than those obtained via other threshold extraction methods; (2) we applied the extraction method to UADLEEZ, and analyzed the expansion of the urban agglomeration based on expansion scale, gravity center offset, and landscape pattern index, the analysis of expansion process is consistent with the actual situation; (3) the proposed method can be used to draw long-term dynamic maps of urban extents in units of years, and the results can be used to update the existing products. This study can serve as a reference for future urban planning, and provide both adjustment programs for relevant departments, and an objective basis for governmental decision-making.

Highlights

In recent years, rapid population, economic, and social development have accelerated urbanization processes in China, leading to a sharp expansion in urban construction land [1]
We reached the following conclusions: (1) the urban built-up areas obtained via our proposed method are finer than those obtained via other threshold extraction methods; (2) we applied the extraction method to UADLEEZ, and analyzed the expansion of the urban agglomeration based on expansion scale, gravity center offset, and landscape pattern index, the analysis of expansion process is consistent with the actual situation; (3) the proposed method can be used to draw long-term dynamic maps of urban extents in units of years, and the results can be used to update the existing products
After a comparison with the actual high definition (HD) satellite image (Google Earth data), we found that the area of the top 60% of the superpixel blocks with the luminous gray value was closest to the actual one

Summary

Introduction

Rapid population, economic, and social development have accelerated urbanization processes in China, leading to a sharp expansion in urban construction land [1]. The urban built-up area in China expanded from 17,416 km in 1992 to 58,456 km in 2018, and the urbanization rate increased from 27.63% to 59.58% during that same period. Because of the increasing pressure resulting from urban land expansion, mapping urban boundaries at regional or larger scales has become an urgent task. Driven by the urbanization process and economic development, urban areas continue to spread to the hinterland of rural areas, the loss of agricultural land has threatened and damaged the ecological environment, and caused a series of social problems, including insufficient resources, land growth rate being higher than population growth rate, and economic problems. Mapping built-up areas involves significant challenges due to the high spatial frequency and heterogeneity of surface features [2]

Methods

Findings

Discussion

Conclusion