Changes between Version 3 and Version 4 of GroupActivities/CodeAvalaibilityPublication/ORCHIDEE-Hillslope-r6515
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- 2021-12-01T14:55:07+01:00 (2 years ago)
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GroupActivities/CodeAvalaibilityPublication/ORCHIDEE-Hillslope-r6515
v3 v4 6 6 ''Xi Y, Peng S, Liu G, Ducharne A, Ciais P, Prigent C, Li X, Tang X. Trade-off between afforestation and wetland conservation in China. Submitted to Nature Communications in October 2021.'' 7 7 8 For more than 20 years, China has been implementing programmes of widespread afforestation to solve the climate change problem. However, afforestation enhances evapotranspiration and reduces runoff, which can cause wetlands to shrink. As yet, the trade-off between afforestation and wetland conservation is unclear. Here, we employ satellite-derived inundation data and a process-based land surface model to investigate the impacts of afforestation on wetland dynamics in China for 2000–2016 and the potential impacts of near-term afforestation activities for 2017–2035. We find that 160,000–190,000 km2 of historical afforestation in wetland grid cells has resulted in 1,300–1,500 km2 wetland loss. Compared to moist southern China, the dry northern and western regions show a much higher sensitivity of wetland reduction to afforestation. With most protected wetlands in China located in the drier northern and western basins, continuing afforestation scenarios are projected to lead to a >10% wetland loss relative to 2000 across 4–8 out of 38 national wetland nature reserves. Given the subtle change in projected precipitation by 2035, spatial optimization of future afforestation activities can help the balance of afforestation and wetland conservation targets in China 8 For more than 20 years, China has been implementing programmes of widespread afforestation to solve the climate change problem. However, afforestation enhances evapotranspiration and reduces runoff, which can cause wetlands to shrink. As yet, the trade-off between afforestation and wetland conservation is unclear. Here, we employ satellite-derived inundation data and a process-based land surface model to investigate the impacts of afforestation on wetland dynamics in China for 2000–2016 and the potential impacts of near-term afforestation activities for 2017–2035. We find that 160,000–190,000 km2 of historical afforestation in wetland grid cells has resulted in 1,300–1,500 km2 wetland loss. Compared to moist southern China, the dry northern and western regions show a much higher sensitivity of wetland reduction to afforestation. With most protected wetlands in China located in the drier northern and western basins, continuing afforestation scenarios are projected to lead to a >10% wetland loss relative to 2000 across 4–8 out of 38 national wetland nature reserves. Given the subtle change in projected precipitation by 2035, spatial optimization of future afforestation activities can help the balance of afforestation and wetland conservation targets in China. 9 9 10 10 ''Arboleda Obando, P., Ducharne, A., Cheruy, F., Jost, A., Colin, Nous, C. Influence of hillslope flow on hydroclimatic evolution under climate change. To be submitted to Earth Future in December 2021.'' 11 11 12 12 We analysed the influence of hillslope flow on the projections of climate change, by comparing two transient climate simulations with the IPSL Climate Model between 1980 to 2100. Hillslope flow induces a reorganization and increment of soil moisture (+10%), which increases evapotranspiration (+4%) and precipitation (+1%), and decreases total runoff (-3%) and air temperature (-0.1°C) on yearly average over land, for 1980-2010, compared to the simulation not representing hillslope flow. These changes in land/atmosphere fluxes are not homogenous, and depend on regional climate and surface conditions. Hillslope flow is also shown to influence climate change projections. On average over land, it amplifies the positive trend of soil moisture (+23%), evapotranspiration (+50%) and precipitation (+7%), and slightly attenuates global warming (-1%), especially for daily maximum air temperature. At a regional scale, the role of hillslope flow in supporting surface/atmosphere fluxes is more evident. Where precipitation is projected to decrease throughout the twenty-first century, hillslope flow is shown to attenuate the related declines of evapotranspiration, precipitation, and total runoff, regardless of aridity conditions and mean air temperature. Where precipitation is projected to increase, in contrast, hillslope flow amplifies evapotranspiration enhancement, but attenuates the increase of precipitation and total runoff, because precipitation is already enhanced during the historical period. Warming is generally attenuated in both cases, especially in semi arid and cold areas, as well as humid and warm/temperate regions, but the signal is weak. These results demonstrate the role of hillslope flow in enhancing water and energy fluxes between the surface and the atmosphere. This enhancement influences climate change trends, and attenuates increase of aridity and decrease of water resources. 13 14 ''Tootchi, A. (2019). Development of a global wetland map and application to describe hillslope hydrology in the ORCHIDEE land surface model, PhD thesis, Sorbonne Université. '' 15 16 Link to [https://www.metis.upmc.fr/%7Educharne/documents/These_Tootchi_revised_11Sep2019.pdf PhD thesis], with model description (under name ORCHIDEE-WET) in chapter 2.2, and evaluation in the Seine basin in chapter 4. 13 17 14 18
