Nonpoint Pollution Source-Sink Landscape Pattern Change Analysis in a Coastal River Basin in Southeast China

Area of Science:

• Environmental Science
• Ecology
• Remote Sensing

Background:

• Nonpoint source pollution management requires understanding river basin landscape dynamics.
• Spatiotemporal analysis of source-sink landscapes is key for effective pollution control.

Purpose of the Study:

• To investigate landscape pattern changes in the Jiulong River basin from 1990 to 2015.
• To analyze the spatiotemporal characteristics of source-sink landscape transitions and their impact on water quality.

Main Methods:

• Utilized Landsat imagery interpreted with a random forest classifier, incorporating texture and spectral information.
• Calculated landscape metrics at the patch level and derived transition matrices to quantify land-use changes.
• Correlated landscape changes with water quality indicators (DO, NH₃-N, TP).

Main Results:

• Residential land increased from 7.42% to 14.55%, with peak fragmentation in 2005.
• Forestland remained dominant (>71%), while unused land decreased.
• Water quality deteriorated (declining DO, rising NH₃-N and TP) between 2005-2015, correlating with increased cultivated land.

Conclusions:

• Jiulong River basin experienced significant landscape fragmentation and unsustainable land transitions over three decades.
• Forestland and unused land were primarily converted to residential and cultivated land.
• These changes negatively impacted water quality, highlighting the need for improved land management strategies.