What are the metrics for assessing the tipping points for a hydrological systems? I know they look appearances and disappearances of species for ecological systems but just wondering if there are any (certain) thresholds for hydrological systems!
One approach for examining whether hydrologic systems have reached a threshold or tipping point is to apply the non-parametric Pettit test to any time series of data you are examining such as discharge, sediment loads, nutrient concentrations, etc. This will help identify whether there has been a shift in the mean and may indicate that the system is rapidly shifting towards a new state. Examining the geographic coherence of these tipping points can point towards regional drivers such as climate change, land use change, and other factors. These references are helpful if you want to perform a statistical exploration of tipping points:
Pettitt, A. (1979). A Non-Parametric Approach to the Change-Point Problem Published by : Wiley for the Royal Statistical Society Stable URL : http://www.jstor.org/stable/2346729 A Non-parametric Approach to the Change-point Problem, Applied Statistics, 28(2), 126–135.
Sagarika, S., Kalra, A., & Ahmad, S. (2014). Evaluating the effect of persistence on long-term trends and analyzing step changes in streamflows of the continental United States. Journal of Hydrology, 517, 36–53. http://doi.org/10.1016/j.jhydrol.2014.05.002.
McCabe, G. J., & Wolock, D. M. (2002). A step increase in streamflow in the conterminous United States. Geophysical Research Letters, 29(24), 38-1-38–4. http://doi.org/10.1029/2002GL015999.
Demaria, E. M. C., Palmer, R. N., & Roundy, J. K. (2016). Regional climate change projections of streamflow characteristics in the Northeast and Midwest U.S. Journal of Hydrology: Regional Studies, 5, 309–323. http://doi.org/10.1016/j.ejrh.2015.11.007.
Well,
the undermentioned article examine this point of view.
Sincerely
Article HYDROLOGIC SYSTEM OF EUPHRATES RIVER (SPATIAL ANALYSIS) BETW...
A few ideas to consider:
Are streams in balance with their flow and sediment (i.e., are they stable, not aggrading or degrading, with access to valley floodplain or flood prone area depending on gradient)?
Is channel network stable or expanding? Have past actions expanded or modified the natural channel network (e.g., gullying)?
Has or is the extent of the perennial and intermittent stream network changed?
In entrenched channel system with existing nickpoints, are they stable or actively migrating?
Are the extent of roads, impervious surfaces, vegetation or forest clearing with watershed producing channel type or substrate changes?
Are activities altering the soil‘s ability to take up and store water?
One approach for examining whether hydrologic systems have reached a threshold or tipping point is to apply the non-parametric Pettit test to any time series of data you are examining such as discharge, sediment loads, nutrient concentrations, etc. This will help identify whether there has been a shift in the mean and may indicate that the system is rapidly shifting towards a new state. Examining the geographic coherence of these tipping points can point towards regional drivers such as climate change, land use change, and other factors. These references are helpful if you want to perform a statistical exploration of tipping points:
Pettitt, A. (1979). A Non-Parametric Approach to the Change-Point Problem Published by : Wiley for the Royal Statistical Society Stable URL : http://www.jstor.org/stable/2346729 A Non-parametric Approach to the Change-point Problem, Applied Statistics, 28(2), 126–135.
Sagarika, S., Kalra, A., & Ahmad, S. (2014). Evaluating the effect of persistence on long-term trends and analyzing step changes in streamflows of the continental United States. Journal of Hydrology, 517, 36–53. http://doi.org/10.1016/j.jhydrol.2014.05.002.
McCabe, G. J., & Wolock, D. M. (2002). A step increase in streamflow in the conterminous United States. Geophysical Research Letters, 29(24), 38-1-38–4. http://doi.org/10.1029/2002GL015999.
Demaria, E. M. C., Palmer, R. N., & Roundy, J. K. (2016). Regional climate change projections of streamflow characteristics in the Northeast and Midwest U.S. Journal of Hydrology: Regional Studies, 5, 309–323. http://doi.org/10.1016/j.ejrh.2015.11.007.
Hi Prabin,
While these aren't really "metrics for assessing tipping points", it could be worthwhile looking at temperature trends and extreme precipitation events. If an area gets warm enough that ice no longer forms on water bodies, I expect that will have some fairly large effects on aquatic ecosystem function, but I'm not sure if it constitutes a tipping point / regime shift. Rainfall extremes sufficient to cause failure of either man-made or beaver dams will also push aquatic environments into a new state, at least for the short term.
Martyn
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