Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 8

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  hydrological drought
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1

Selected characteristics of hydrological drought progression in the upper Warta river catchment

100%
Kozek M., Tomaszewski E.
Acta Scientiarum Polonorum. Formatio Circumiectus
|
2018
|
tom 17
|
nr 3
In the present study, identification of hydrological drought was made, assuming that the low-flow period, which is a symptom of drought, is also a good estimator of its progression. The research was conducted in the upper Warta river catchment, for which the series of daily discharge for 12 gauging stations from the period 1971–2000 were available. The low-flow periods were identified on the basis of the constant threshold level, which corresponds to the 70th percentile of the flow duration curve (Q70%). For the identified low-flow episodes, parameters pertaining to its duration, streamflow deficit, and flow dynamics have been estimated. The established identification and separation criteria made it possible to assess the simple and compound hydrological droughts. Transformation of characteristics related to low-flow duration, relative drought streamflow deficit as well as low-flows’ share in the total number of gauging stations resulted in the evaluation of hydrological drought in terms of its severity and range. The characteristics, which constitute estimators of hydrological drought progression and recession rate, made it possible to define the determinants of the studied phenomenon along with its variability in time.
2

Low-flow discharge deficits assessment, applying constant and variable low-flow threshold levels, as illustrated with the example of selected catchments in the Vistula River basin

88%
Tomaszewski E.
Acta Scientiarum Polonorum. Formatio Circumiectus
|
2018
|
tom 17
|
nr 3
In the present study, we have assessed low-flow discharge deficits, and the characteristics of the low flows at a constant and variable (monthly) low-flow threshold. The low-flow truncation level was identified based on the 70th percentile from the flow duration curve (Q70%). Q95% was assumed to be the threshold for the deep low-flow discharge. Thirteen catchments in the Vistula basin, varying in size, river regime, and physico-geographical conditions, were selected for the study. The input data was a series of daily discharge data sets from the period 1951–2016, made available by IMGW-PIB (Polish Institute of Meteorology and Water Management – National Research Institute). Analyses were conducted of drought flow discharge deficit volume in absolute and relative values, and low-flow duration and deficits contributing to severe low-flows were calculated for temporal scales of months and years. Comparison of the obtained results led us to the determination of the basic factors affecting the formation of low-flow deficits, and the indication of restrictions when applying fixed and variable criteria for identifying river low-flows.
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A comparison of hydrological drought characteristics defined by the POT and SPA methods in the Dunajec River basin

63%
Baran-Gurgul K.
Infrastruktura i Ekologia Terenów Wiejskich
|
2014
|
nr IV/3
This paper addresses the problem of how drought definition by POT and SPA methods influences drought characteristics. Using the 1984- 2013 daily flows at 24 selected gauging stations in the Dunajec river basin and assuming two threshold levels Q70% and Q95% and four minimum drought durations (5, 7, 10 and 14 days) as the pre-set criteria, it was shown that, when compared to the POT method, the application of the SPA method usually leads to less number of droughts and, consequently, of longer duration. The SPA method, differently from POT, reduces dramatically the number of inter-event times, which suggests that some adjacent POT droughts may be dependent and should be pooled.
4
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Streamflow droughts and probability of their occurrence in a small agricultural catchment

63%
Kaznowska E., Banasik K.
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation
|
2011
|
tom 43
|
nr 1
The goal of this work consists in quantitative analysis of the occurrence of droughts and their occurrence probability estimated for a small agricultural catchment on the basis of a multi-annual series of daily streamflows in the Zagożdżonka river at the Płachty Stare gauging station, in the context of observed changes in the stream regime during the multi-annual period 1963-2010. The Zagożdżonka river catchment is one of a few in Poland, with long-term records on rainfall and runoff. To identify streamflow droughts in daily discharge hydrograms, truncation level Q90% (discharge determined from the flow duration curve) was used. Minimum duration of drought amounting to 10 days, was the additional criterion for identification of droughts. The Nizowka2003 model was used for finding distributions of the probability of deficit volume and duration of maximum summer droughts for the Zagożdżonka river. The droughts in the small agricultural catchment under study concern only summer half-years and most often they are of short duration – up to 20 days. Longer droughts, lasting lightly over 2 months, can be expected – once per 10 years. The occurrence of a summer drought lasting almost all the season in the Zagożdżonka river is probable once per 100 years. A weak correlation between the minimum drought discharge and their duration was found.
5

Changes in the intensity and frequency of occurrence of droughts in Poland [1891-1995]

63%
Mager P., Kuznicka M., Kepinska-Kasprzak M., Farat R.
Geographia Polonica
|
2000
|
tom 73
|
nr 2
6

Ocena intensywnosci nizowek rzecznych w malej zlewni rolniczej Niziny Mazowieckiej w ostatnich 45 latach

51%
Kaznowska E., Banasik K.
Acta Scientiarum Polonorum. Formatio Circumiectus
|
2009
|
tom 08
|
nr 3-4
5-16
Rolnicza zlewnia rzeki Zagożdżonki położona jest na Nizinie Mazowieckiej, należącej do tych regionów kraju, w których najczęściej występują susze. Celem pracy jest analiza niżówek rzeki Zagożdzonki w profilu Płachy Stare w latach 1963–2007. Materiał wyjściowy do analiz stanowiły wyznaczone parametry niżówek w profilu. W celu określania okresów niżówkowych na hydrogramach dobowych przepływów zastosowano metodę polegającą na wyznaczaniu niżówek za pomocą poziomów odcięcia – SNQ i Q90%. Najdłuższa i najsurowsza pod względem deficytu odpływu była niżówka w 1964 roku. W rozpatrywanym okresie nie zaobserwowano niżówek zimowych. W ostatnich latach badanego wielolecia niżówki występują co rok, jednak ich rozmiary i intensywność nie osiągają takiego poziomu jak w wypadku niżówek z lat ubiegłych.
7

The effect of hydrological drought on chemical quality of water and dissolved organic carbon concentrations in lowland rivers

51%
Zielinski P., Gorniak A., Piekarski M. K.
Polish Journal of Ecology
|
2009
|
tom 57
|
nr 2
217-227
The effects of drought on river water quality and dissolved organic carbon (DOC) fluctuations were studied in 22 lowland rivers in north-east Poland with different size (from 3.3 km to 77.2 km), and discharge (mostly in range 1–8 m³ s⁻¹). The extensive agriculture, housing and plantation forestry (afforestation from 7% to 97%) dominate in the landuse in catchments. All investigated rivers were characterized by similar hydrological regime and relatively high natural level of organic matter in waters (10 mg DOC dm⁻³). The autumn 2000 drought in Poland was one of the most severe in many years when the monthly sum of precipitation in October made only 6% of average long-term norm for the region. Significant differences in concentrations of investigated chemical parameters were noted between results from wet (1996–1998) and dry (2000) autumn periods. Concentrations of ions derived from non-point sources increased in many locations, which was confirmed by increases in Ca, and HCO₃ concentrations. Average dissolved organic carbon concentrations, and water colour were two times higher in the wetter autumn than in dry period. The hydrological drought in autumn 2000 caused significant decrease in the range of DOC concentrations (about 30%). The largest difference in DOC concentrations between the wet autumn period and extremely dry one were recorded in the rivers flowing through dense forests. Our results indicate that dissolved organic carbon in most natural catchments decreased as a result of the lack of dilution. Some more natural north-east Polish rivers gradually lost contact with their catchments, and ecotone zones did not play an important role in supplying organic matter to rivers during droughts. Most of river and catchment morphological parameters became less important in shaping the amounts of DOC in rivers. The current study indicates that small and medium rivers were not resistant in hydrochemical terms to flow decreases what has environmental consequences for transport of nutrients, organic matter and finally on sediments, flora and fauna habitats.
8

Skuteczność działania regulowanego odpływu w okresach suszy hydrologicznej i ekstensywnej eksploatacji obiektu

38%
Pokladek R., Nyc K.
Zeszyty Problemowe Postępów Nauk Rolniczych
|
2008
|
tom 528
Na eksploatowanych systemach melioracyjnych Samotwór i Miękinia k. Wrocławia, wyposażonych w urządzenia do regulowania odpływu wód powierzchniowych i gruntowych, prowadzone są badania kształtowania się zasobów małej retencji gruntowej. Stwierdzono, że w przypadku dobrej melioracyjnej i rolniczej eksploatacji obiektów, pojawiająca się okresowo susza atmosferyczna nie powodowała występowania deficytu wody glebowej. Wahania poziomów wód gruntowych nie przekraczały 30-50 cm na obiekcie Samotwór i 20 cm w Miękini przy korzystniejszych warunkach hydrologicznych.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.