Climate and landuse change enhance spatio-temporal variability of Dongjiang river flow and ammonia nitrogen

Sci Total Environ. 2023 Apr 1;867:161483. doi: 10.1016/j.scitotenv.2023.161483. Epub 2023 Jan 9.


The adverse impacts of climate and landuse change are threatening the availability of water quantity and its quality, yet there are limited understandings in the response of water availability to changing environment at different spatio-temporal scales. Aimed at quantifying the individual and superimposed effects of climate and landuse change on streamflow and ammonia nitrogen (NH3-N) load in the Dongjiang River Basin (DRB), we dynamically simulated the historical (1981-2010) and future (2030-2070) variation of runoff depth and NH3-N load coupling multiple regional climate model and landuse data. The increase in runoff depth (avg. +233.9 mm) due to climate change was about 33 times greater than that caused by landuse change (avg. -7.2 mm). Especially in the downstream of DRB (Hong Kong, Shenzhen and Dongguan cities, etc.), the maximum rise of runoff depth under climate change was near twice compared with baseline period, indicating the dominant control of climate change on runoff. Also there existed higher coefficient of variation (Cv) value of runoff in the dry season of downstream DRB, contributing potential great fluctuation in runoff. Besides, the variation of NH3-N load was jointly influenced by climate and landuse change, revealing an offset or amplification effect. Moreover, the variability of NH3-N load (Cv value as the metric) increased from 2030, reached a maximum in 2050, following decreased to 2070. The spatial distribution of NH3-N load, in general, presented a downward trend and concentrated near the water body, while the monthly average NH3-N load showed distinct peaks in spring and late summer temporally. Overall, the results highlight the significance of investigating the water availability under changing environment and more adaptive strategies should be proposed for better basin water management.

Keywords: Ammonia nitrogen; Climate change; Landuse change; Streamflow; Variability and contribution.