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It) I. PHYSICAL GEOGRAPHY.
Table 3. Characteristic Levels of the Water in
River or Lake Station Winter low-water Spring high-water
Date Height Date Height
Lulcälv ........ Trån»fors ..... 22 April - 172 3 July + 256
Indalsälven....... Bomsund ...... 29 March — 116 6 June + 264
Lj åsnan........ Edänge....... 29 » - 68 19 May + 215
Dalälven........ Alvkarleö ..... 15 » — 105 31 * + 182
Byskeälv........ Mvrheden ..... 7 April - 38 21 » + 7ft
Gideälv ........ Björna ....... 25 March - 41 18 t + 75
Delångersån....... Näsviken...... 31 » – 25 5 June + 42
Södra Barken ...... Senila....... 8 » — 23 17 May + 76
Fvrisån ........ Uppsala...... 1 > - 33 16 April + 106
Emån......... Järnforsen..... 14 Fehr. — 15 17 s + 95
Helgeån........ Hönjebro...... 10 > — 11 31 March + 42
Nissan......... Johansfors..... 14 > — 2:-5 4 April + 71
Mjörn ......... Skår........ 24 > 10 15 > + 46
the stream named having, probably, the lowest run-off of all the mountain rivers.
The figures rise again for the mountain rivers of Central Sweden (the
Dalälven = 430; the Klarälven = 450 millimeters), owing to the large precipitation
in the mountainous districts on the boundaries between Dalarne, Värmland, and
Norway, and in Western Bergslagen. The run-off probably amounts to between
50 and 75 % of the rainfall.
The exceptional high-water discharges vary between 69 and 140 second-liters
per square kilometer, but, as was mentioned above, they are somewhat uncertain.
The normal high-water discharges vary between 39 and 88 second-liters per
square kilometer. The normal low-water volumes remain at about 3—4 second-liters
per square kilometer; the exceptional ones fall to 1"5—3 second-liters per square
kilometer.
The forest- and littoral rivers present far fewer variations. In the type-rivers
given in Table 3, for instance, the absolute variations lie between 113 and 202
centimeters. The winter low-water level in these rivers, too, is the lowest of
the year, but the summer level also falls considerably, and, in the case of the
Central Swedish streams especially, it is, as a rule, about as low as that
prevailing in the winter. This is connected with the far more transient and
earlier spring-floods, as well as with the greater evaporation from the tracts with
abundant forests and bogs. In consequence of the smaller extent of these basins
and of their uniform character, there is, as a rule, only one flood in the
springtime, with its maximum usually about the middle or the end of May. Autumn
high-water is a frequent occurrence. The curves in the Diagram show, especially
for these rivers, the rise of level which occurs during the winter as a result of
the extensive damming of the waters occasioned at that season by the ice, and
which plays an extremely important role in these streams with their narrow
beds and inconsiderable calm-water basins.
The average run-off is considerably lower than that of the mountain rivers,
this being the case especially in Norrland, in the eastern parts of which the
rainfall is not so great (the Byskeälv = 340 millimeters). It is greatest in the
West-Central Swedish rivers, which discharge their waters into Vänern (the
Gull-spångsälven = 460 millimeters), the run-off from which is even greater than that
of the highland rivers of Central Sweden. The run-off percentage probably varies
between 40 and 60 %.
The high-water discharges appear to be relatively low, the result, probably, of
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