rootwater.rootwater The root water uptake (RWU) toolbox

The root water uptake (RWU) toolbox

Root water uptake (RWU) can be inferred from soil moisture dynamics in the rhizosphere (Feedes and van Dam, 2005; Guderle and Hildebrandt, 2015). We developped a function to evaluate the step-shaped, diurnal changes in soil moisture to derive an estimate for RWU. The science behind this function is presented in a case study by Jackisch et al. (in review)

Note

This function is by no means complete nor exhaustive. Please regard it as helper function which require throughout testing and deserve substantial extension to further application cases.

Note

For direct application (tested for TDR measurements at two beech stands) use rootwater.rootwater.dfRWUc and provide a pandas.DataFrame with measured soil moisture (in vol.%).

References

Feddes, R. A., and J. C. van Dam (2005), PLANT–SOIL–WATER RELATIONS, in Encyclopedia of Soils in the Environment, edited by D. Hillel, pp. 222–230, Elsevier, Oxford.

Guderle, M., and A. Hildebrandt (2015), Using measured soil water contents to estimate evapotranspiration and root water uptake profiles – a comparative study, Hydrol. Earth Syst. Sci., 19(1), 409–425, doi:10.5194/hess-19-409-2015.

Jackisch, C., Knoblauch, S., Blume, T., Zehe, E. and Hassler, S.K. (in review): Estimates of tree root water uptake from soil moisture profile dynamics. Submitted to Biogeosciences. DOI to be added

rootwater.rootwater.dfRWUc(dummyd, tz='Etc/GMT-1', safeRWU=True, lat=49.70764, lon=5.897638, elev=200.0, savgol=False)[source]

Wrapper to quickly apply rootwater.rootwater.fRWU to a dataframe with soil moisture values.

Returns three dataframes with RWU, RWU_without nocturnal correction, step shape NSE Warning: All parameters for the function rootwater.rootwater.fRWU are used as default!

Parameters:
  • dummyd (pandas.DataFrame with time zone aware datetime index) – input data frame of columns of soil moisture (assumes vol.%) a relatively high temporal resolution of about 30 min or smaller is assumed
  • tz (str) – time zone which is required for the astral solar reference and follows its nomenclature
  • safeRWU (bool) – flag if quality controls are applied when True
  • lat (float) – latitude of location (degree)
  • lon (float) – longitude of location (degree)
  • elev (float) – elevation at location (m above msl)
Returns:

  • dummx (pandas.DataFrame) – data frame with time series of daily RWU estimates with applied nocturnal correction
  • dummy (pandas.DataFrame) – data frame with time series of daily RWU estimates WITHOUT nocturnal correction
  • dummc (pandas.DataFrame) – data frame with time series of Nash-Sutcliff-Efficiency as evaluation of the assumed step shape of the diurnal soil moisture dynamics.

References

Jackisch, C., Knoblauch, S., Blume, T., Zehe, E. and Hassler, S.K. (in review): Estimates of tree root water uptake from soil moisture profile dynamics. Submitted to Biogeosciences. DOI to be added

rootwater.rootwater.fRWU(ts, lat=49.70764, lon=5.897638, elev=200.0, diffx=3, slope_diff=3, maxdiffs=0.25, mintime=3.5)[source]

Calulate a daily root water uptake estimate from a soil moisture time series

Returns a data frame with time series of daily RWU estimates and daily evaluation references after Jackisch et al. (in review)

Parameters:
  • ts (pandas.DataFrame with time zone aware datetime index) – time series of one soil moisture sensor (assumes vol.%) a relatively high temporal resolution of about 30 min or smaller is assumed
  • lat (float) – latitude of location (degree)
  • lon (float) – longitude of location (degree)
  • elev (float) – elevation at location (m above msl)
  • diffx (int) – number of time steps to evaluate change in moisture to (spans window)
  • slope_diff (float) – minimal difference factor of slope between night and day linear regession to evaluate step shape especially in case of night decrease of soil moisture
  • maxdiffs (float) – maximum of soil moistue difference to assume no significant other water transport (some sort of threshold which could be the noise of the sensed data)
  • mintime (float) – minmimal time of a day or night period (in h)
Returns:

RWU – returns a data frame with time series of daily RWU estimates and daily references: rwu :: root water uptake with extrapolated night changes rwu_nonight :: neglecting nocturnal changes lm_night :: slope of linear model during night lm_day :: slope of linear model during day step_control :: control values (1111 means all criteria met) evalx :: control values for time references eval_nse :: control values for diurnal step shape as nash-sutcliffe efficiency tin :: start of previous night tout :: start of day tix :: start of next night
Return type:

pandas.DataFrame

References

Jackisch, C., Knoblauch, S., Blume, T., Zehe, E. and Hassler, S.K. (in review): Estimates of tree root water uptake from soil moisture profile dynamics. Submitted to Biogeosciences. DOI to be added