308
J. Fac-Beneda et al.
to the occurrence of groundwater outflows. Their yield oscillates from just under 0.1
to about 30 dm
3 s
−1 [12]. The outflow waters feed the lake in a significant way and
quadruple the volume of the flow of the W˛ egorza (the tributary of the Łeba) flowing
through Lake Lubowidzkie.
The catchments of the Pomeranian rivers belong to the richest in flowing water
resources in Poland with the relatively stable outflow and high unit outflows [3]. The
underground structure has a significant share (over 70%) of underground outflow
[7, 13]. This value is much above the average for Poland. For the catchment of the
Słupia, the share of underground water supply significantly exceeds the average for
Poland and amounts to about 80%, while the average annual value of unit runoff
exceeds q = 10 dm
3 s
−1 km
−2 [3]. A high share of underground outflow should
be attributed to good conditions of infiltration in numerous areas lacking outflow,
and a large thickness of well-permeable surface rock layers. High importance is also
attributed to subglacial channels, ice-marginal valleys, and deep-cut river valleys
draining deep groundwater [14]. For the South Baltic Lake Districts, including the
Pomeranian catchment, the hierarchical organisation of outflow is characteristic.
The water cycle here depends more on the zonal factors, and less on local factors.
The main river is the axis of the system; in its lower course, it has allochthonous
character, while the main river’s function consists in draining surplus water coming
from the source catchments. Often also several catchments participate in the process
of discharging water surpluses. It is the case in the Kashubian hydrographic system
(ksh), the Bytów hydrographic system (bsh), and the Drawsko hydrographic system
(dsh) [15].
16.2 Atmospheric Inflow
The climate of Pomerania exhibits features attributed to mid-latitudes showing
the transitional nature of oceanic and continental influences. What is strongly
pronounced here is the predominance of advection of moist air masses from the
west, as well as instability, expressed in the variability of weather conditions all year
round [16]. However, the range of the Baltic Sea influence and the morphological
contrast between the raised and diversified relief of the lake district and the coastal
plains are of vital importance in shaping the climate conditions of Pomerania. It
is reflected in the distinct climatic regions of this area. It is assumed that the direct
impact of the sea is limited to a 20–30 km wide strip of land [17]. The influence of the
sea determines radiation and aerodynamic, thermal and hygrometric features of the
climate. On the coast, one of the most significant amounts of solar energy in Poland
is recorded, both on a yearly and summer basis (from May to August). It is favoured
by the summer length of the day and relatively small convection-type overcast. The
development of overcast, especially in May and June, is inhibited by the occurrence
of the sea breeze circulation. As a result, in the coastal zone, the average annual real
sunshine duration is 100 h longer (1700 h) than in the watershed zone separating the
northern and southern slopes of Pomerania (1600 h).
J. Fac-Beneda et al.
to the occurrence of groundwater outflows. Their yield oscillates from just under 0.1
to about 30 dm
3 s
−1 [12]. The outflow waters feed the lake in a significant way and
quadruple the volume of the flow of the W˛ egorza (the tributary of the Łeba) flowing
through Lake Lubowidzkie.
The catchments of the Pomeranian rivers belong to the richest in flowing water
resources in Poland with the relatively stable outflow and high unit outflows [3]. The
underground structure has a significant share (over 70%) of underground outflow
[7, 13]. This value is much above the average for Poland. For the catchment of the
Słupia, the share of underground water supply significantly exceeds the average for
Poland and amounts to about 80%, while the average annual value of unit runoff
exceeds q = 10 dm
3 s
−1 km
−2 [3]. A high share of underground outflow should
be attributed to good conditions of infiltration in numerous areas lacking outflow,
and a large thickness of well-permeable surface rock layers. High importance is also
attributed to subglacial channels, ice-marginal valleys, and deep-cut river valleys
draining deep groundwater [14]. For the South Baltic Lake Districts, including the
Pomeranian catchment, the hierarchical organisation of outflow is characteristic.
The water cycle here depends more on the zonal factors, and less on local factors.
The main river is the axis of the system; in its lower course, it has allochthonous
character, while the main river’s function consists in draining surplus water coming
from the source catchments. Often also several catchments participate in the process
of discharging water surpluses. It is the case in the Kashubian hydrographic system
(ksh), the Bytów hydrographic system (bsh), and the Drawsko hydrographic system
(dsh) [15].
16.2 Atmospheric Inflow
The climate of Pomerania exhibits features attributed to mid-latitudes showing
the transitional nature of oceanic and continental influences. What is strongly
pronounced here is the predominance of advection of moist air masses from the
west, as well as instability, expressed in the variability of weather conditions all year
round [16]. However, the range of the Baltic Sea influence and the morphological
contrast between the raised and diversified relief of the lake district and the coastal
plains are of vital importance in shaping the climate conditions of Pomerania. It
is reflected in the distinct climatic regions of this area. It is assumed that the direct
impact of the sea is limited to a 20–30 km wide strip of land [17]. The influence of the
sea determines radiation and aerodynamic, thermal and hygrometric features of the
climate. On the coast, one of the most significant amounts of solar energy in Poland
is recorded, both on a yearly and summer basis (from May to August). It is favoured
by the summer length of the day and relatively small convection-type overcast. The
development of overcast, especially in May and June, is inhibited by the occurrence
of the sea breeze circulation. As a result, in the coastal zone, the average annual real
sunshine duration is 100 h longer (1700 h) than in the watershed zone separating the
northern and southern slopes of Pomerania (1600 h).