Sediment flux sensitivities to climate change and human activities
Abstract
Sediment flux from large Chinese rivers to coasts have dramatically declined from around 2 Gt/yr to less than 0.5 Gt/yr. Such dramatic decline was predominately due to human activities such as reservoirs construction, vegetation recovery, sand mining and water withdrawal. However, climate changes, mainly through changes in precipitation, also impacted on sediment flux. Yet it is not straightforward to differentiate both climate changes and multiple human impacts.
Lu et al. (2013) estimated that lower precipitation coupled with rising temperatures has significantly reduced sediment loads delivered into the sea in semi-arid climates (4-61%). In contrast, increasingly warmer and wetter climates in subtropical zones has yielded more sediment (0.4-11%), although the increase was offset by human impact. The results also indicated that every 1% change in precipitation has resulted in a 1.3% change in water discharge and a 2% change in sediment loads. In addition, every 1% change in water discharge caused by precipitation has led to a 1.6% change in sediment loads, but the same percentage of water discharge change caused largely by humans would only result in a 0.9% change in sediment loads. To test whether these results also apply to other river basins, we collected sediment flux data from over 100 river basins and separated climate changes and human impacts on sediment fluxes. We found very similar results, i.e. sediment fluxes were more sensitive to precipitation changes than water in both north and south China. Thus, the results from our past research can be used as a guideline for evaluating the responses of sediment fluxes to climate change in similar climate zones because future global warming will cause dramatic changes in water and sediment in river basins worldwide at rates previously unseen.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP53F2207L
- Keywords:
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- 1813 Eco-hydrology;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1826 Geomorphology: hillslope;
- HYDROLOGY