Early winter hydrograph

Stage = 40.5cm, Ta = 2.0 degrees C

Above average snowpack has accumulated at Takiya River so far this winter. Today conditions were fine, allowing us to download the river water level data and the snow lysimeter data, as well as undertaking snow surveys. The hydrograph below shows the typical pattern for early winter, where increasingly heavy rains during December cause several moderate peaks, followed by a period of flow recession as rain turns to snow and snowpack accumulates in the basin.

The chart above shows the hourly lysimeter runoff for the mature cedar (evergreen) and larch (deciduous) study sites between 12 December and 14 January. During this season, all of the large peaks in runoff are due to rain-on-snow events. If you look at the hydrograph above, you will see that the peaks for lysimeter runoff are linked to peaks in the basin runoff, as for example the rain-on-snow event on December 24-25 (note: horizontal time-axes are not the same range). The small peak in lysimeter runoff at the very end (January 13-14) is due to melting of intercepted snow in the cedar forest canopy, while interception melt is minimal at the larch site.

Larch lysimeter site

Mature cedar lysimeter site