Nízký SNWE na Travném

2025-03-08 22:41 UTC o3-mini-high Open in ChatGPT ↗

It’s possible those values really are water‐equivalent (the liquid content if all the snow were melted), not the snow depth in centimeters of snow on the ground. That distinction can make the numbers look surprisingly “small,” even though they may represent a fair amount of actual snow depth. However, whether ~0.21 m of water equivalent (≈21 cm of water) is realistic for the summit area around Travný depends on exactly where and how the measurements were taken:

1. Water equivalent vs. snow depth

A water equivalent of ~0.21 m could correspond to somewhere around 70 cm to well over 1 m of actual snow on the ground, depending on the snow’s density. So the bar heights in the chart would look modest if you’re used to seeing snow depths in centimeters of actual snow rather than water equivalent.

2. Measurement location matters

If these data are from a lower‐altitude station (e.g. a village at the foot of Travný rather than the summit), a maximum of 20 cm of water equivalent might not be surprising. Snow in valley or foothill stations can be much less than up on the ridge or peak.
If the data are supposed to represent a high‐altitude site near the summit (over 1200 m), then in many winters you’d expect water equivalents exceeding 0.21 m. In that case, you might suspect a problem with how or where the data were recorded.

3. Potential data issues

Sometimes the dataset is mislabeled (for instance, monthly means vs. daily maxima) or includes data from only part of the winter season.
Check if there’s a metadata file describing which station, altitude, and method of measurement (e.g. snow pillows vs. manual snow‐course surveys) were used.
Ensure that “m of water equivalent” hasn’t been confused with some other unit or that there wasn’t a systematic undercatch or station bias.

Bottom line

If these measurements truly represent a lower‐elevation site, then peaking around 0.20–0.21 m of water equivalent can be reasonable for a Czech mountain foothill station.
If you expected data from high on Travný itself—where you’d anticipate deeper snow—then these numbers do look suspiciously low, and you may want to verify the measurement site, altitude, and unit labeling.

The short answer is that “meters of water equivalent” (m w.e.) measures the depth of liquid water if you melted the snowpack, whereas “meters of snow depth” depends on the snow’s density. If the snow is light and fluffy (low density), it takes more depth of snow to yield the same amount of water when melted; if the snow is heavier (higher density), it takes less.

The calculation in a nutshell

1 m of water has a density of ~1000 kg / m³.
Snow density can vary widely—fresh powder can be ~100 kg / m³, while older, compacted snow might be 300–400 kg / m³ (or even more).
To find the snow depth (in meters) that corresponds to a given water equivalent, you can use:

$ \text{Snow depth}
Section titled “$ \text{Snow depth}”

\frac{\text{Water‐equivalent depth}}{\rho_\text{snow} ,/, \rho_\text{water}}
Section titled “\frac{\text{Water‐equivalent depth}}{\rho_\text{snow} ,/, \rho_\text{water}}”

\text{Water‐equivalent depth} \times \frac{\rho_\text{water}}{\rho_\text{snow}}. $

where $\rho_\text{water} \approx 1000,\mathrm{kg/m^3}$ and $\rho_\text{snow}$ is the snow density.

Example for 0.21 m water equivalent

Assume a typical mid‐winter density of around 300 kg/m³.
Then $\rho_\text{snow} / \rho_\text{water} \approx 300/1000 = 0.3.$
Therefore,

$ \text{Snow depth} \approx 0.21,\text{m (water eq.)} \times \frac{1}{0.3} ;=; 0.21,\text{m} \times 3.3 ;=; 0.69,\text{m}. $

That’s roughly 70 cm of snow.

If the snow were fluffier (say density 200 kg/m³), the ratio would be 1 / 0.2 = 5, so 0.21 m w.e. corresponds to about 1 m of snow. Conversely, if the snow were denser (e.g. 400 kg/m³), the ratio is 1 / 0.4 = 2.5, so 0.21 m w.e. is about 50 cm of snow.

Hence the rule of thumb that 0.20–0.21 m w.e. might mean anywhere from ~50 cm to over a meter of actual snow on the ground, depending on its density.

Whether 0.20 m³/m³ (i.e., 20% volumetric water content) is “low” for Silver Fir (Abies alba) depends heavily on the soil’s texture and the typical field capacity for that site:

1. Volumetric water content vs. field capacity

Volumetric water content (VWC) is simply the fraction of soil volume that is water (e.g., 0.20 m³ water per 1 m³ of soil).
Field capacity is the water content the soil holds after excess water has drained away (roughly the upper “normal” limit of moisture in the root zone).

Typical field capacities for various soil textures:

Sandy soils: ~0.15–0.20 m³/m³
Loamy soils: ~0.25–0.35 m³/m³
Clay soils: ~0.35–0.45 m³/m³

If your soil is sandy and its field capacity is near 0.20 m³/m³, then a measured 0.20 m³/m³ may actually be near field capacity and not necessarily “dry.” But if your soil is loam or clay, 0.20 m³/m³ could be significantly below field capacity, indicating relatively dry conditions.

2. Silver Fir’s moisture requirements

Silver Fir (Abies alba) is native to cooler, moist, often mountainous regions of central and southern Europe. It typically thrives where soils do not dry out too much in summer. Prolonged or severe soil moisture deficits can stress Silver Fir, especially on sites where the water table is lower or the soil is coarse and drains quickly.

On loamy or clay‐rich soils: 0.20 m³/m³ is likely well below field capacity, so the fir may experience water stress.
On sandy soils: 0.20 m³/m³ might be close to the maximum water the soil can actually hold, so it might be acceptable.

3. Key takeaway

Yes, 0.20 m³/m³ can be considered low if you are dealing with a medium‐textured or fine‐textured soil. That moisture level could be suboptimal for Silver Fir, possibly indicating dryness stress.
No, it might not be “too low” if the site’s soil is naturally coarse and 0.20 m³/m³ is near field capacity.

So the answer hinges on soil texture and local conditions. If you suspect the site normally holds more water than 0.20 m³/m³, Silver Fir might indeed be moisture‐stressed at that level.