Response of Urban River Water Quality to Human Activity Intensity: Evidence Synthesis and Data Analysis of the Lam Tsuen River

The Lam Tsuen River has an area of 424 hectares and exhibits significant differences in “nature-village-urban”. Although many monitoring data have been obtained since 2020 and 2024, there is still not enough integrated results yet. Reviewing existing research, comparing the key effects, and re-analysing the five-year official-monitoring data in this paper. A systematic review of the literature (1986-2025). Collecting monthly water quality data at five observation points (TR12C, TR12D, TR12F, TR12G and TR12H) via EPD records and the CSDI database. Mann-Kendall test; Descriptive analysis method; t-test; Curve fitting methodology. Results show that there are indeed spatial differences caused by urbanisation, but TR12C station at the upstream is obviously abnormal for ammoniacal nitrogen, indicating localised single-pollutant points; There are two obvious changes of suspended solids: first during summer which is likely due to non-point sources; Then downstream stations have relatively significant reduction in ammonia nitrogen and increased concentration of dissolved oxygen (p<0.05); A nonlinear relationship between built-up area ratio and ammonia-nitrogen concentration was found (with an apparent turning point around 51.6). The above results generally correspond to the region, and they also need confirmation.