500
G. Romanescu and I. Minea
tributary flow of 5533.0 m
3 /s (137.39%). The highest increases were recorded on the
rivers of Siret (221.53%) and Pruth (218.18%) (Table 15.5). The fact that some plants
had higher amounts of water passing through the turbines was due to the excess water
recorded in the previous year.
For the mean multi-monthly tributary flow, data corresponding to over 13 years
was analyzed (2000–2012). It is worth stating that, in ensuring a low degree of error,
hydrological data must be analyzed for, at least, 30 years. The mean monthly tributary
flow for the period between October 2011 and April 2012 (7 months) was low, compared to the mean multi-monthly tributary flow for rivers comprising hydropower
units (Table 15.6). Most values ranged between 60 and 70% of the mean multimonthly tributary flow. In the period October 2011–April 2012 (7 months), the
Danube recorded a mean flow of 3789.3 m
3 /s. This is lower compared to the mean
multi-monthly flow of 5664.41 m
3 /s (66.89%) for the period 2000–2012.
The period between the month of October 2011 and April 2012 (7 months), the
Danube recorded a mean flow of 3789.3 m
3 /s, compared to the mean multi-monthly
flow for the period between the year 2000 and 2012 (for the months of October 2011,
November 2011, December 2011, January 2012, February 2012, March 2012, and
April 2012)—5664.41 m
3 /s (66.89%). The period between the year 2000 and 2010
recorded higher mean values for flows throughout the entire country (in the year 2005,
2006, 2008, and 2010, historic floods occurred on the Romanian territory). Even
under these circumstances, the mean monthly tributary flows recorded in October
2011–April 2012, represented only 60–70% (for some arteries, values were even
lower). Over a longer period, values can be slightly different, and they feature a
descending trend (concerning values of 40–50%).
The interval, 30.09.2011–30.04.2012 recorded low amounts of precipitations for
the entire river network in Romania. The lowest values of mean flows were recorded
in November 2011 and January–February, 2012, because precipitations were reduced
and temperatures were very low (February). Mean flows ranged between 30 and 50%
of the multi-annual monthly means. The lowest values (<30% of the normal monthly
values) were recorded in November, December, and January, on the rivers situated
in the southwest of Romania, and in February, on the rivers situated in the west and
in the eastern hill and plain areas. The month of April recorded values close to the
normal monthly values in Banat, Transylvania, Crisana, and Maramures.
At the hydrometric station of Bazias, on the Danube (entry into Romania), the
mean monthly flows, which is lower than the multiannual monthly means by 53–78%
were recorded. The lowest values were recorded in the months of November–December, 2011 and in February 2012 (53–57% of the monthly means). The lowest
daily value was 2150 m
3 /s, and it was recorded within the period, 22–23.02.2012
[22]. For the entire recording period—between the year 1921 and 2014 (94 years),
the interval between September and March (7 months)—at the hydrometric station of
Orsova (upstream from HPP Iron Gates), droughts were recorded between the years,
1921–1922, 1946–1947, 1953–1954, 1990–1991, and 2011–2012. The droughtiest
periods turned out to be between the years, 1953–1954 and 2011–2012. The mean
multi-monthly flow for the period, September–March (7 months) was 2480 m
3 /s
(1953–1954) and 3340 m
3 /s (2011–2012). In this case, the flow of 3340 m
3 /was
G. Romanescu and I. Minea
tributary flow of 5533.0 m
3 /s (137.39%). The highest increases were recorded on the
rivers of Siret (221.53%) and Pruth (218.18%) (Table 15.5). The fact that some plants
had higher amounts of water passing through the turbines was due to the excess water
recorded in the previous year.
For the mean multi-monthly tributary flow, data corresponding to over 13 years
was analyzed (2000–2012). It is worth stating that, in ensuring a low degree of error,
hydrological data must be analyzed for, at least, 30 years. The mean monthly tributary
flow for the period between October 2011 and April 2012 (7 months) was low, compared to the mean multi-monthly tributary flow for rivers comprising hydropower
units (Table 15.6). Most values ranged between 60 and 70% of the mean multimonthly tributary flow. In the period October 2011–April 2012 (7 months), the
Danube recorded a mean flow of 3789.3 m
3 /s. This is lower compared to the mean
multi-monthly flow of 5664.41 m
3 /s (66.89%) for the period 2000–2012.
The period between the month of October 2011 and April 2012 (7 months), the
Danube recorded a mean flow of 3789.3 m
3 /s, compared to the mean multi-monthly
flow for the period between the year 2000 and 2012 (for the months of October 2011,
November 2011, December 2011, January 2012, February 2012, March 2012, and
April 2012)—5664.41 m
3 /s (66.89%). The period between the year 2000 and 2010
recorded higher mean values for flows throughout the entire country (in the year 2005,
2006, 2008, and 2010, historic floods occurred on the Romanian territory). Even
under these circumstances, the mean monthly tributary flows recorded in October
2011–April 2012, represented only 60–70% (for some arteries, values were even
lower). Over a longer period, values can be slightly different, and they feature a
descending trend (concerning values of 40–50%).
The interval, 30.09.2011–30.04.2012 recorded low amounts of precipitations for
the entire river network in Romania. The lowest values of mean flows were recorded
in November 2011 and January–February, 2012, because precipitations were reduced
and temperatures were very low (February). Mean flows ranged between 30 and 50%
of the multi-annual monthly means. The lowest values (<30% of the normal monthly
values) were recorded in November, December, and January, on the rivers situated
in the southwest of Romania, and in February, on the rivers situated in the west and
in the eastern hill and plain areas. The month of April recorded values close to the
normal monthly values in Banat, Transylvania, Crisana, and Maramures.
At the hydrometric station of Bazias, on the Danube (entry into Romania), the
mean monthly flows, which is lower than the multiannual monthly means by 53–78%
were recorded. The lowest values were recorded in the months of November–December, 2011 and in February 2012 (53–57% of the monthly means). The lowest
daily value was 2150 m
3 /s, and it was recorded within the period, 22–23.02.2012
[22]. For the entire recording period—between the year 1921 and 2014 (94 years),
the interval between September and March (7 months)—at the hydrometric station of
Orsova (upstream from HPP Iron Gates), droughts were recorded between the years,
1921–1922, 1946–1947, 1953–1954, 1990–1991, and 2011–2012. The droughtiest
periods turned out to be between the years, 1953–1954 and 2011–2012. The mean
multi-monthly flow for the period, September–March (7 months) was 2480 m
3 /s
(1953–1954) and 3340 m
3 /s (2011–2012). In this case, the flow of 3340 m
3 /was