Abstract

Urban lakes play an important role in urban development and environmental protection for the Wuhan urban agglomeration. Under the impacts of urbanization and climate change, understanding urban lake-water extent dynamics is significant. However, few studies on the lake-water extent changes for the Wuhan urban agglomeration exist. This research employed 1375 seasonally continuous Landsat TM/ETM+/OLI data scenes to evaluate the lake-water extent changes from 1987 to 2015. The random forest model was used to extract water bodies based on eleven feature variables, including six remote-sensing spectral bands and five spectral indices. An accuracy assessment yielded a mean classification accuracy of 93.11%, with a standard deviation of 2.26%. The calculated results revealed the following: (1) The average maximum lake-water area of the Wuhan urban agglomeration was 2262.17 km2 from 1987 to 2002, and it decreased to 2020.78 km2 from 2005 to 2015, with a loss of 241.39 km2 (10.67%). (2) The lake-water areas of loss of Wuhan, Huanggang, Xianning, and Xiaogan cities, were 114.83 km2, 44.40 km2, 45.39 km2, and 31.18 km2, respectively, with percentages of loss of 14.30%, 11.83%, 13.16%, and 23.05%, respectively. (3) The lake-water areas in the Wuhan urban agglomeration were 226.29 km2, 322.71 km2, 460.35 km2, 400.79 km2, 535.51 km2, and 635.42 km2 under water inundation frequencies of 5%–10%, 10%–20%, 20%–40%, 40%–60%, 60%–80%, and 80%–100%, respectively. The Wuhan urban agglomeration was approved as the pilot area for national comprehensive reform, for promoting resource-saving and environmentally friendly developments. This study could be used as guidance for lake protection and water resource management.

Highlights

  • Urban lakes provide numerous ecosystem services that are closely related to human well-being in both the present and future

  • It mainly consisted five parts: the collection of feature variables, collection of training samples, image consisted of five parts: the collection of feature variables, collection of training samples, imageare classification based on the random forest model, rule filter, and accuracy assessment

  • The results showed that lake-water extraction based on the random forest model respectively

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Summary

Introduction

Urban lakes provide numerous ecosystem services that are closely related to human well-being in both the present and future. These ecosystem services include agricultural production, fishery resources, flood mitigation, water storage, and entertainment locations [1,2]. All of these ecosystem services are affected by fluctuations in the lake-water extent over time and space [3]. The Wuhan urban agglomeration—consisting of Wuhan, Huangshi, Ezhou, Xiaogan, Huanggang, Xianning, Xiantao, Qianjiang, and Tianmen—is one of five national urban agglomerations and has extensive lake-water extent, due to its wet climate.

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