decreasing trend in flood volume in the Biebrza Valley within the period
1961–2000, permits the assumption that the climate-induced changes in spring
flood dynamics has become an issue in ecosystem continuity and function (especially for water-dependent terrestrial habitats of marshes and for fish species). This
fact, which can partly remain controlled by water management in the upper parts of
the Biebrza catchment, is suspected to be the main challenge for migratory birds
such as geese, which are strongly dependent on the flood occurrence and extent
(Polakowski et al. 2011). The earlier appearance of floods along with the decreasing
volume of the flood wave limit the extent of fish spawning and induce an increasing
in-situ fertilisation of meadows with the remains of vegetation and nutrients from
previous seasons. Variability in the spring flood dynamics is of minor importance to
agriculture, as field activities such as haymaking start later, once the spring flood
has finished (May–June). Contradictorily, the changing dynamics of summer floods
remain a challenge for both the agricultural maintenance of wetlands and ecosystems, remaining the most significant climate-related pressure on ecosystems and
management for wetlands in the Biebrza Valley.
The analysis of precipitation and flood dynamics in the Biebrza Valley leads to
the general conclusion that (1) during the analysed period of 1970–2010 the share
of summer precipitation in the annual sum of precipitation has decreased, (2) maximum daily volumes of precipitation have increased, which expresses the increasing frequency of extreme precipitation events, (3) significant increase in sizeable
summer floods occurrence (Q > 84.1 m
3 /s) was reported in the period 2001–2011
compared to the years 1951–2000, and (4) the regular spring floods in the Biebrza
Valley start under average contemporary conditions approximately 10 days earlier
than in the 1950s.
14.3.2 Projections
As some visible trends in precipitation dynamics and flooding in the Biebrza Valley
were observed (Fig. 14.2), the next step of our research was to establish and assess
prospective climate change projections for the Biebrza Wetlands. Climate change data
for the Biebrza Valley was derived from the ENSEMBLES project results (van den
Linden and Mitchell 2009; after Stagl and Hattermann 2011). There were ten different
GCM-RCM combinations for the SRES A1B emission scenario considered with
regard to climate change impact analysis in the Biebrza Valley: HadCM3-C4I/
RCA3, CNRM/Arpege-DMI/HIRHAM5, ECHAM5-DMI/HIRHAM5, HadCM3ETHZ/CLM3.21, HadCm3Q0-HC/HadRM3Q0, HadCM3Q16-HC/HadRM3Q16,
HadCm3Q3-HC/HadRM3Q3, ECHAM5-ICTP/REGCM3, BCM-SMHI/RCA3 and
HadCM3Q3-SMHI/RCA3. Prospective relative changes in monthly sums of precipitation [P; mm] and average monthly air temperatures [T;
C] in the time horizon
2070–2100 were referred to the values of average monthly temperature and precipitation recorded at the Laskowiec monitoring station of the BNP (see Fig. 14.1) in the
years 2000–2011. As ten different GCM-RCM-emission scenario combinations were
216
M. Grygoruk et al.
1961–2000, permits the assumption that the climate-induced changes in spring
flood dynamics has become an issue in ecosystem continuity and function (especially for water-dependent terrestrial habitats of marshes and for fish species). This
fact, which can partly remain controlled by water management in the upper parts of
the Biebrza catchment, is suspected to be the main challenge for migratory birds
such as geese, which are strongly dependent on the flood occurrence and extent
(Polakowski et al. 2011). The earlier appearance of floods along with the decreasing
volume of the flood wave limit the extent of fish spawning and induce an increasing
in-situ fertilisation of meadows with the remains of vegetation and nutrients from
previous seasons. Variability in the spring flood dynamics is of minor importance to
agriculture, as field activities such as haymaking start later, once the spring flood
has finished (May–June). Contradictorily, the changing dynamics of summer floods
remain a challenge for both the agricultural maintenance of wetlands and ecosystems, remaining the most significant climate-related pressure on ecosystems and
management for wetlands in the Biebrza Valley.
The analysis of precipitation and flood dynamics in the Biebrza Valley leads to
the general conclusion that (1) during the analysed period of 1970–2010 the share
of summer precipitation in the annual sum of precipitation has decreased, (2) maximum daily volumes of precipitation have increased, which expresses the increasing frequency of extreme precipitation events, (3) significant increase in sizeable
summer floods occurrence (Q > 84.1 m
3 /s) was reported in the period 2001–2011
compared to the years 1951–2000, and (4) the regular spring floods in the Biebrza
Valley start under average contemporary conditions approximately 10 days earlier
than in the 1950s.
14.3.2 Projections
As some visible trends in precipitation dynamics and flooding in the Biebrza Valley
were observed (Fig. 14.2), the next step of our research was to establish and assess
prospective climate change projections for the Biebrza Wetlands. Climate change data
for the Biebrza Valley was derived from the ENSEMBLES project results (van den
Linden and Mitchell 2009; after Stagl and Hattermann 2011). There were ten different
GCM-RCM combinations for the SRES A1B emission scenario considered with
regard to climate change impact analysis in the Biebrza Valley: HadCM3-C4I/
RCA3, CNRM/Arpege-DMI/HIRHAM5, ECHAM5-DMI/HIRHAM5, HadCM3ETHZ/CLM3.21, HadCm3Q0-HC/HadRM3Q0, HadCM3Q16-HC/HadRM3Q16,
HadCm3Q3-HC/HadRM3Q3, ECHAM5-ICTP/REGCM3, BCM-SMHI/RCA3 and
HadCM3Q3-SMHI/RCA3. Prospective relative changes in monthly sums of precipitation [P; mm] and average monthly air temperatures [T;
C] in the time horizon
2070–2100 were referred to the values of average monthly temperature and precipitation recorded at the Laskowiec monitoring station of the BNP (see Fig. 14.1) in the
years 2000–2011. As ten different GCM-RCM-emission scenario combinations were
216
M. Grygoruk et al.