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EN
This study aims to evaluate changes in the frequency and severity of historical droughts (1980–2018) and then model future droughts occurrences (2019–2099) in the Lepelle River Basin (LRB), using Intergovernmental Panel on Climate Change (IPPC) General Circulation Model (GCM) simulations for two representative concentration pathways (RCP8.5 and RCP4.5). Firstly, the present-day and future hydrology of the LRB are modelled using the weather evaluation and planning (WEAP) model. Mann–Kendall tests are conducted to identify climate trends in the LRB. The reconnaissance drought index (RDI) and the streamflow drought index (SDI) are employed to explore hydro-meteorological droughts in the Lepelle River Basin, South Africa. The RDI and SDI are plotted over time to assess drought magnitude and duration. The simulated temporal evolution of RDI and SDI show a significant decrease in wetting periods and a concomitant increasing trend in the dry periods for both the lower and middle sections of the LRB under RCP4.5 as the 22nd century is approached. Lastly, the Spearman and Pearson correlation matrix is used to determine the degrees of association between the RDI and SDI drought indices. A strong positive correlation of 0.836 is computed for the middle and lower sections of the LRB under the RCP8.5 forcing. Further findings indicate that severe to extreme drought above –2.0 magnitude are expected to hit the all three sections of the LRB between 2080 and 2090 under RCP8.5. In the short term, it is suggested that policy actions for drought be implemented to mitigate possible impacts on human and hydro-ecological systems in the LRB.
EN
A three decade-long study on the variability of drought in relation to the contribution of rainfall was conducted at the Wadi Mekerra watershed, located in northwest Algeria, covering the period from 1973 to 2005. The runoff and rainfall data were analyzed using the Mann-Kendall test, the double mass curve method and the SPI index. A rupture of the studied series appeared during the 1980s. The rainfall and runoff trends and contributions were in general, sharply reduced. The region experienced extreme drought between 1981 and1989, and between 1993 and 2001, rainfall contributions were greater than 60%. This increase, which was recorded in August, September and October for all the parameters studied, shows the importance of the superficial runoff component when combined with decreased infiltration. These climatic conditions reduce the natural recharging of groundwater, and cause an increased susceptibility to soil erosion, reduced agricultural production and an increased risk of floods.
EN
Drought is an extreme event that causes great economic and environmental damage. The main objective of this study is to evaluate sensitivity, characterization and propagation of drought in the Upper Blue Nile. Drought indices: standardized precipitation index (SPI) and the recently developed standardized reconnaissance drought index (RDIst) are applied for five weather stations from 1980 to 2015 to evaluate RDIst applicability in the Upper Blue Nile. From our analysis both SPI and RDIst applied for 3-, 6-, 12 month of time scales follow the same trend, but in some time steps the RDIst varies with smaller amplitude than SPI. The severity and longer duration of drought compared with others periods of meteorological drought is found in the years 1984, 2002, 2009, 2015 including five weather stations and entire Upper Blue Nile. For drought relationships the correlation analysis is made across the time scales to evaluate the relationship between meteorological drought (SPI), soil moisture drought (SMI), and hydrological drought (SRI). We found that the correlation between three indices (SPI, SMI and SRI) at different time scales the 24-month time scale is dominant and are given by 0.82, 0.63 and 0.56.
PL
Susza jest ekstremalnym zjawiskiem, które powoduje ogromne straty ekonomiczne i szkody środowiskowe. Celem badań było określenie wrażliwości na suszę, charakterystyk i propagacji suszy w regionie górnego Nilu Błękitnego. Dwa wskaźniki suszy – wskaźnik standaryzowanego opadu (SPI) i niedawno opracowany wskaźnik RDIst (ang. standardized reconnaissance drought index) zastosowano do danych z pięciu stacji meteorologicznych z lat 1980 do 2015, aby ocenić przydatność tego drugiego do oceny sytuacji w regionie. Z analiz przeprowadzonych przez autorów niniejszej publikacji wynika, że oba wskaźniki wykazywały podobny trend zmian w przedziałach czasowych 3-, 6- i 12-miesięcznych, ale w pewnych okresach wskaźnik RDIst cechowała mniejsza amplituda zmian niż wskaźnik SPI. W odniesieniu do pięciu stacji meteorologicznych i całego obszaru górnego biegu Nilu Błękitnego najbardziej surowe i długotrwałe susze stwierdzono w latach 1984, 2002, 2009 i 2015 w porównaniu z innymi latami badań. Wykonano także analizę korelacji między wskaźnikami suszy meteorologicznej SPI, suszy glebowej SMI i suszy hydrologicznej SRI. Najsilniejszą korelację między tymi wskaźnikami stwierdzono dla 24-miesięcznych przedziałów czasowych, a odpowiednie współczynniki korelacji wynosiły 0,82, 0,63 i 0,56.
EN
Drought is one of the important phenomena resulting from variability and climate change. It has negative effects on all economic, agricultural and social sectors. The objective of this study is to rapidly detect climate dryness situations on an annual scale at the Mellah catchment (Northeast Algeria) for periods ranging from 31 years through the calculation of: the standardized precipitation index (SPI), the standardized Streamflow index (SSFI), the standardized temperature index (STI). Calculations made it possible to locate periods of drought more precisely by their intensity, duration and frequency, and detect years of breaks using the tests of Pettitt, rang, Lee and Heghinian, Hubert and Buishand. The use of the statistical tests for the rainfall series analyzed show all breaks, the majority of which are in 1996/1997 and 2001/2002. For the temperatures the breaks are situated in 1980/1981.
PL
Susza jest jednym z ważnych zjawisk wywoływanych zmianami klimatu. Wywiera ujemny wpływ na gospodarkę, rolnictwo i społeczeństwo. Celem przedstawionych badań było śledzenie sytuacji suszy klimatycznej w skali roku w zlewni Mellah (północnowschodnia Algieria) w ciągu 31 lat przez obliczenia: standaryzowanego wskaźnika opadu (SPI), standaryzowanego wskaźnika przepływu (SSFI) i standaryzowanego wskaźnika temperatury (STI). Obliczenia z zastosowaniem testów Petitta, rang, Lee i Heghiniana oraz Huberta i Buishanda umożliwiły dokładniejsze ustalenie okresów suszy przez analizę intensywności, czasu trwania i częstotliwości, umożliwiły też wykrycie lat przerw w ciągach suszy. Dzięki testom statystycznym dla serii analizowanych opadów wykazano okresy przerw, głównie w latach 1996/1997 i 2001/2002. Dane temperaturowe wskazywały na okresy przerw w latach 1980/1981.
EN
Drought is generally associated with the persistence of low precipitation amount, decreased soil moisture and water availability relative to the normal levels in a designated area. The effects of drought, range from the morphological to molecular levels, and are evident at all phenological stages of the plant growth, at whatever stage the water deficit occurs. Determination of the surface water demands for irrigation purposes comes out from the assumption of hydrologic processes stationarity. This paper shows our research prerequisite that water stress participates in an important part on the volume changes of over ground parts, which is predictive for the irrigation demand. Malus domestica var. Yellow Transparent was chosen for the measurement of volume changes of the surface plant parts. Our measurements were realised by the Diameter dendrometer small (DD-S) from 24.08. to 13.09.2017. One tree was irrigated by the dose of 50 mm. We compared the dendrometric changes to soil moisture and rainfall on both irrigated and non-irrigated trees. The experiment showed the differences between the irrigated apple tree (the diameters of the branches fluctuated between 11.9 and 12.1 mm) and the non-irrigated apple tree (the diameter of the branches increased after three-day rain from 8.35 to 8.61 mm), in order to determine the water stress of plants based on dendrometric changes and optimize irrigation during the drought period.
EN
The conversion of peatland from forest to non-forest causes environmental damage and increases high land dryness. Mapping of peatland based on dryness is very important to control and prevent fires. This study aims at characterizing peatland based on the level of temperature vegetation dryness index (TVDI) and evaluating the correlation between TVDI value and soil moisture. The research was conducted in August 2018 during the dry season. The area of research located in peat hydrological unit of Sibumbung River – Batok River in Ogan Komering Ilir (OKI) District of South Sumatra Province covering 63,427 ha area that consists of various land uses. The result showed that extreme wet category is found in water bodies and secondary forests that have high density, moderate wet is found in paddy fields and grass, normal area is found in the area covered by low-density trees, moderate dry is found in shrubs and oil palm plantations with good management and extreme dry areas is found in grasses and oil palm with poor cultivation management. There is a correlation between the TVDI value to the soil moisture on 0–10 cm and 10–20 cm and 20–30 cm depth.
7
Content available remote Problematyka zjawiska suszy a systemy zaopatrzenia w wodę
PL
Jednym z bieżących wyzwań w gospodarowaniu zasobami wodnymi jest nasilające się w ostatnich latach występowanie susz. Negatywne konsekwencje tego zjawiska dotyczą licznych aspektów życia i gospodarki. Długotrwały brak opadów oraz wysokie temperatury powietrza powodują pogarszanie się jakości wód i zmniejszanie ich ilości, możliwych do wykorzystania na potrzeby zaopatrzenia ludności. Dotyczy to wód powierzchniowych oraz poziomu wód podziemnych. W niniejszym artykule zaprezentowano problematykę oddziaływania zjawiska suszy na zaopatrzenie w wodę systemów wodociągowych, zauważalną szczególnie w małych i średnich miastach.
EN
One of the current challenges in water management is the rising occurrence of droughts in recent years. The negative consequences of this phenomenon relate to many aspects of life and economy. Long-term lack of rain and high air temperatures cause the deterioration of water quality and reduce their quantity, possible to be used for public supply. This applies to the level of surface water and groundwater. This article presents the problem of the impact of the drought phenomenon on water supply in water supply systems, particularly noticeable in small and medium-sized cities.
PL
W artykule wykorzystano dostępne informacje o aktywności słonecznej wykazującej ok. 11-letnią cykliczność i powiązano ją z czasem wystąpienia powodzi i susz w dorzeczu Odry w ostatnich 50 latach. Zachodzi wyraźna zbieżność największych wezbrań opadowych z okresami niższej aktywności słonecznej oraz występowania susz w okresach po wystąpieniu maksimum tej aktywności. Pokazuje to, że aktywność słoneczna może być istotnym czynnikiem wspomagającym długoterminowe przewidywanie (ryzyka) wystąpienia powodzi na południu Polski. Ta korelacja wskazuje na podwyższone ryzyko wystąpienia niebezpiecznych powodzi w dorzeczu Odry i/lub Wisły w perspektywie 1-3 lat (do 2021 r.).
EN
The article is based on the available information concerning the solar activity indicating its 11-years’ periodicity and linking it to the pattern of occurrence of floods and droughts in the Oder River basin in the last 50 years. There is an evident convergence between the largest rainfall floods and the periods of lower activity of the sun, as well as the occurrence of floods following the activity peaks. It indicates that the solar activity may be an important factor used for long-term forecast of (the risk of) floods in the southern part of Poland. This correlation shows higher risk of the occurrence of dangerous floods in the Oder and/or Vistula basin in 1-3 years’ perspective (until 2021).
PL
Na podstawie danych z bazy GIS Mapy Hydrogeologicznej Polski w skali 1:50 000 ustalono optymalne warunki dla intensywnego poboru wody studniami wierconymi z poziomów wodonośnych podczas długotrwałej suszy hydrologicznej na obszarze pasa nizin środkowopolskich o najniższych w kraju opadach atmosferycznych i głębokich niedoborach wody na terenach upraw rolnych w okresie suszy. Zależnie od warunków hydrogeologicznych i rodzaju gleb, pobór z pojedynczej studni może w okresie głębokiej suszy hydrologicznej pokryć wysokie niedobory wody na terenach upraw rolnych na powierzchni najczęściej 15–50 ha, natomiast czas odbudowy retencji sczerpanych zasobów w ujętym poziomie wodonośnym wyniesie najczęściej 1–5 lat.
EN
Based on the GIS database for the 1: 50,000 Hydrogeological Map of Poland, the optimum conditions have been established for intensive water abstraction by drilled wells from aquifers during a long-lasting hydrological drought in the central regions of the Polish Lowlands. It is the area of country’s lowest precipitation and high water deficits for agriculture during droughts. Depending on the hydrogeological conditions and the type of soils, water abstraction from a single well can cover high water deficit for agriculture during a period of deep hydrological drought in an area of most frequently 15–50 hectares. The time of retention recovery in the aquifer for depleted resources will usually be 1–5 years.
11
Content available remote Niestabilność wartości parametrów niżówek hydrogeologicznych
PL
W pracy poruszono zagadnienia zmienności wartości parametrów naturalnie występujących okresów niskich stanów wód podziemnych. Zbadano stabilność wybranych charakterystyk niżówek hydrogeologicznych w czasie i w profilu pionowym – w kolejno zalegających poziomach wodonośnych. Wykorzystano w tym celu dane o położeniu zwierciadła wód z wybranych stacji sieci obserwacyjno-badawczej Państwowego Instytutu Geologicznego – Państwowego Instytutu Badawczego z lat 1979–2018. W poszczególnych otworach badawczych w różnych krokach czasowych, wynoszących od 10 do 20 lat, wykazano dużą niestabilność wartości parametrów niżówek hydrogeologicznych, takich jak: maksymalny i średni czas trwania zjawiska, liczba zdarzeń czy częstość osiągania stanu niższego niż stan średni niski. Ponadto we wszystkich analizowanych stacjach pierwszego rzędu, gdzie monitoring obejmował więcej niż jeden poziom wodonośny, stwierdzono, że wartości badanych parametrów różniły się od siebie w zależności od obserwowanego poziomu wodonośnego. Lokalne uwarunkowania hydrogeologiczne powodowały, że czas niżówek w głębszych poziomach wydłużał się albo skracał w stosunku do pierwszego poziomu wodonośnego. Uzyskane wyniki świadczą o bardzo zróżnicowanej wrażliwości na suszę poszczególnych, badanych warstw wodonośnych.
EN
The study concerns instability of parameters of low groundwater level periods in time and space – in subsequent water-bearing layers. Based on the data collected from selected observation stations of the Polish Geological Institute – National Research Institute between 1979 and 2018, time series of groundwater levels were examined to test the maximum and average duration of low groundwater level periods, total number of continuous events, and the frequency of reaching a lower groundwater level than the average low level. The instability of parameters at various time steps ranging from 10 to 20 years is demonstrated. Furthermore, in each tested first-order station, where various water-bearing layers at different depths were monitored simultaneously, the values of all tested parameters varied depending on the observed layer. The duration of low groundwater periods in deeper water-bearing layers can be either longer or shorter than in the case of the first horizon and depends on local hydrogeological conditions.
PL
Suszę atmosferyczną określa się często poprzez analizę niedoboru opadów na danym obszarze w badanym przedziale czasowym. Do identyfikacji suszy służą różne wskaźniki, z których w niniejszym opracowaniu wybrano: wskaźnik standaryzowanego opadu SPI (ang. Standardized Precipitation Index), wskaźnik względnego opadu RPI (ang. Relative Precipitation Index) i wskaźnik hydrotermiczny K Sielianinowa. W opracowaniu wykorzystano dane dotyczące średniej dobowej temperatury powietrza oraz dobowej sumy opadów atmosferycznych z trzydziestu stacji IMGW-PIB w miesiącach od kwietnia do października z lat 1966-2015. Dokonano oceny okresu wegetacyjnego w kolejnych latach pod względem niedoboru opadów przy wykorzystaniu wybranych wskaźników w badanym okresie, przedstawiono liczbę miesięcy charakteryzujących się suszą o różnym stopniu nasilenia, ich udział w okresie wegetacyjnym oraz zróżnicowanie przestrzenne na badanym obszarze. Należy stwierdzić, że do wyznaczania występowania okresów suszy w kolejnych latach znaczenie wyboru wskaźnika jest mniejsze niż w przypadku wyznaczenia okresów o różnej intensywności suszy. Występowanie suszy atmosferycznej w Polsce w okresie wegetacyjnym jest bardzo zróżnicowane, stąd niekompletna i niewystarczająca jest ocena suszy na podstawie uśrednionych wartości wskaźników dla całego obszaru Polski.
EN
Atmospheric drought is often referred to by analyzing the rainfall deficit in a given area for a specified period. Different indicators are used to identify the drought, from which the Standardized Precipitation Index (SPI), Relative Precipitation Index (RPI) and the hydrothermal K Sielianinov Index have been selected. The data of average daily air temperature and daily precipitation totals from 30 IMGW-PIB stations in April-October from years1966-2015 were used. An assessment of the growing period in the following years in terms of rainfall shortage using selected indicators over the analyzed period showed the number of months characterized by varying degrees of severity of drought, their share in the growing period and spatial variation in the studied area. It should be noted that to determine the occurrence of drought periods in subsequent years, the significance of the indicator choice is smaller than when drought intensities are determined. The occurrence of atmospheric drought in Poland during the vegetation period is very diverse, hence the drought assessment based on averaged values of indicators for the whole area of Poland is incomplete and insufficient.
EN
Over the last decades, Algeria has witnessed intense and persistent drought periods characterized by a significant rainfall deficit. The Northwestern Algeria, such as the most south Mediterranean regions, is marked by alternating wet and dry periods and mixing between Atlantic and Mediterranean airs. In a climate context increasingly disturbed by anthropogenic activities, it is essential to analyze the dry episodes at spatial and temporal scales. In order to understand this problem, this work aims to use the potential of Landsat satellite imagery for monitoring drought conditions in the Cheliff watershed in the northwestern Algeria. As known, the behavior of vegetation is strongly related to climate changes. On this basis, a comparison of the variations in the standardized normalized difference vegetation index (NDVI) and those of the drought indices calculated from meteorological data was implemented. In fact, the rainfall series from fifty meteorological stations were analyzed. The standardized precipitation index (SPI) was calculated for the years 1987, 2000, 2006, 2011 and 2015, corresponding to the acquisition dates of Landsat images. Similarly, an extraction of the NDVI values was performed for each meteorological station. The linear regression between SPI and NDVI showed a good correlation. Thus, the obtained results enabled establishing a new drought index based essentially on satellite data. This index represents the advantage for monitoring spatially the drought phenomena and can solve the problem of climatic data lack.
EN
In traditional climate diagrams a fixed coefficient (α) between temperature and precipitation has been adopted. It has been shown, however, that such an approach does not correctly describe the conditions of the climatic balance in Poland for the entire growing season. In this paper, a different solution to this problem is proposed - the introduction of a variable coefficient for individual months. The analysis of patterns of climatic variables over the year supports the hypothesis that in order to estimate ETo only by means of mean air temperature (ETo = α·T), the coefficient α should be variable for the individual months of the vegetative period. The values of the coefficient were empirically determined for use in calculating daily and monthly ETo. The newly proposed coefficients α were different from those determined with the standard climate diagram (published by Walter, Lieth 1967). The introduction of the variable value α into the computational model markedly improved the quality of the estimation of ETo. The mean bias errors determined for the estimation of ETo on the basis of temperature and the changing value of α were considerably lower than for the estimation of ETo with a fixed value of α. This provides the possibility of a more accurate presentation of periods of both excess and shortage of precipitation.
EN
Hydrological drought index analysis has been widely developed and applied for the development of water resources. The island of Lombok, which is largely a dry land, requires a significant hydrological drought index to be sourced from measurable data analysis. This research focused aims to obtain hydrological drought index in Lombok Island using the capacity change of reservoir. The analysis includes reservoir data especially in the event of El-Nino. The main parameters analysed in this work are data homogeneity, decrease line of reservoir volume, increase in the line of reservoir volume, reservoir volume deficit, and hydrological drought index (RDI). The basic equation uses the water balance in the reservoir, which is the inflow–outflow and change of reservoir. The results of the analysis show that in the event of El-Nino, the drought hydrological index indicates different levels depending upon the water level of the reservoir. The criteria for the drought level are as follows: weak RDI = from −0.46 to −0.01 at an reservoir elevation of 90.88 to 92.33 m a.s.l, moderate RDI: from −0.59 to −0.46 at water level of reservoir from 90.27 to 90.88 m a.s.l, sever RDI: from −0.80 to −0.59 at water level of reservoir from 88.83 to 90.27 m a.s.l. and very severe RDI: from −0.89 to −0.80 at water level of water reservoir 87.78–88.83 m a.s.l. The duration of drought was 9 months, i.e., from February to November.
PL
Analiza wskaźnika suszy hydrologicznej ma szerokie zastosowanie w zarządzaniu zasobami wodnymi. Na ubogiej w wodę wyspie Lombok wskaźnik suszy powinien być określany na podstawie analizy mierzalnych danych. Przedstawione w niniejszej pracy badania miały na celu ustalenie wskaźnika dla wyspy z wykorzystaniem zmian pojemności zbiornika. Podstawą analiz były dane o zbiorniku, szczególnie podczas wystąpień El-Niño. Głównymi parametrami analizowanymi w tej pracy były: homogeniczność danych, linia spadku objętości zbiornika, linia wzrostu objętości zbiornika, deficyt objętości zbiornika i wskaźnik suszy hydrologicznej (RDI). Podstawowe równanie ujmuje bilans wody w zbiorniku, tzn. dopływ, odpływ i zmiany objętości. Wyniki analiz wskazują, że w trakcie trwania El-Niño wskaźnik suszy hydrologicznej przyjmował różne wartości w zależności od poziomu wody w zbiorniku. Kryteria natężenia suszy były następujące: słaba susza – RDI od –0,46 do –0,01, gdy poziom wody w zbiorniku wynosił od 90,88 do 92,33 m n.p.m., umiarkowana susza – RDI od –0,59 do –0,46, gdy poziom wody od 90,27 do 90,88 m n.p.m., silna susza – RDI od –0,80 do –0,59, gdy poziom wody od 88,83 do 90,27 m n.p.m. i bardzo silna susza – RDI od –0,89 do –0.80, gdy poziom wody od 87,78 do 88,83 m n.p.m. Susza w trakcie bardzo silnego El-Niño trwała 9 miesięcy od lutego do listopada.
EN
The dam of Hammam Boughrara is an embankment dam built in a transboundary basin, between Algeria and Morocco; it was type-approved and delivered in 1998. This dam was supposed to solve the lack of drinking water in Oran (Algeria's second largest city) and enhance the agricultural perimeter of the area. It should regulate an annual water volume of 59 million m3. However, the northwest Algeria has experienced a fairly severe drought since the 80s. This article aims to show the impact of this drought on the amount of surface water that can be mobilized by this dam. The rainfall series recorded at four stations, located within the basin of the dam, were examined using the proportional deviation from the average, the running average, the frequency analysis, the Pita’s index and the standardized precipitation index. These methods have shown a significant decrease of rain, starting from the hydrological year 1975/1976. These same approaches were also used to analyse series of flows spread over a longer period. This fact revealed three periods of drought which are 1940–1945, 1955–1967 and the most recent one highlighted by the rainfall series, starts at the year 1975/1976. The regularized water volume of the dam, calculated from the series of flow rates, is around 37 million m3. This value reflects a deficit of 40% of the regularized volume predicted by the designers of the dam.
PL
Zaporę Hammam Boughrara zbudowano na granicy Algierii i Maroka i uruchomiono w 1998 r. Zapora miała na celu rozwiązać problem braku wody pitnej w Oranie (drugim co do wielkości mieście Algierii) i zwiększyć zasięg rolnictwa w regionie. Miała regulować rocznie zasoby wody o objętości 59 milionów m3. Północnozachodnie regiony Algierii doświadczają jednak silnej suszy od lat osiemdziesiątych XX wieku. Artykuł ma wykazać wpływ tej suszy na ilość wody, którą może gromadzić zbiornik. Serie opadowe notowane w czterech stacjach zlokalizowanych w zlewni zbiornika analizowano z wykorzystaniem proporcjonalnego odchylenia od średniej, ruchomej średniej, analizy częstości, wskaźnika Pity i wskaźnika standaryzowanego opadu. Stosowane metody wykazały istotne zmniejszenie ilości opadu począwszy od roku hydrologicznego 1975/1976. Takie samo podejście zastosowano do analizy serii szybkości przepływu, które obejmują dłuższy okres. Analiza ujawniła trzy okresy suszy, które przypadały na lata 1940–1945, 1955–1967 i ostatni wykazany przez serie opadów, który rozpoczął się w roku 1975/1976. Zasoby wody regulowane rocznie obliczone z serii przepływów wynoszą ok. 37 milionów m3. Ta ilość w istocie odzwierciedla deficyt gromadzonej wody, gdyż jest o 40% mniejsza niż objętość przewidywana przez projektantów zapory.
EN
The studies on agricultural droughts require long-term atmospheric, hydrological and meteorological data. On the other hand, today, the possibilities of using spectral data in environmental studies are indicated. The development of remote sensing techniques, increasing the spectral and spatial resolution of data allows using remote sensing data in the study of water content in the environment. The paper presents the results of the analysis of moisture content of soil-plant environment in the lowland areas of river valley using the spectral data from Sentinel-2. The analyses were conducted between February and November 2016. The spectral data were used to calculate the Normalize Differential Vegetation Index (NDVI) which provided the information about the moisture content of the soil-plant environment. The analyses were performed only on grasslands, on 22 objects located in the research area in the Oder river valley between Malczyce and Brzeg Dolny, Poland. The NDVI values were correlated with the hydrological and meteorological parameters. The analyses showed spatial and temporal variability of the moisture conditions in the soil-plant environment showed by the NDVI variability and existence some relationships between the climatic and spectral indices characterizing the moisture content in the environment.
EN
The purpose of this research was to identify major drought events on the Spanish mainland between 1961 and 2014 by means of two drought indices, and analyze the spatial propagation of drought conditions. The indices applied were the standardized precipitation index (SPI) and the standardized evaporation precipitation index (SPEI). The first was calculated as standardized anomalies of precipitation at various temporal intervals, while the second examined the climatic balance normalized at monthly scale, incorporating the relationship between precipitation and the atmospheric water demand. The daily meteorological data from Spanish Meteorological Archives (AEMet) were used in performing the analyses. Within the framework of the DESEMON project, original data were converted into a high spatial resolution grid (1.1 km2) following exhaustive quality control. Values of both indices were calculated on a weekly scale and different timescales (12, 24 and 36 months). The results show that during the first half of the study period, the SPI usually returned a higher identification of drought areas, while the reverse was true from the 1990s, suggesting that the effect from atmospheric evaporative demand could have increased. The temporal propagation from 12- to 24-month and 36-month timescales analyzed in the paper seems to be a far from straightforward phenomenon that does not follow a simple rule of time lag, because events at different temporal scales can overlap in time and space. Spatially, the propagation of drought events affecting more than 25% of the total land indicates the existence of various spatial gradients of drought propagation, mostly east–west or west–east, but also north–south have been found. No generalized episodes were found with a radial pattern, i.e., from inland to the coast.
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Content available remote Adaptacja wskaźnika SPI na potrzeby monitorowania suszy w wodach podziemnych
EN
The Standardized Precipitation Index (SPI) proposed by Thomas McKee, Nolan Doesken i John Kleist in 1993 is currently one of the most common meteorological index applied in the assessment of drought intensity. It serves for the quantitative assessment ofprecipitation deficit within an agreed time scale. The advantage of the SPI is that it can be applied at different time scales and different climatic conditions. It provides an early warning information regarding droughts and is helpful in the assessment of its severity. The authors propose that the method can be applied in, apart from precipitation, assessments of river flows, depth of snow cover, water resources in reservoirs, soil wetness and groundwater levels. The article proposes an index formula that allows for the assessment of drought in groundwater. Gamma distribution, which is most commonly used in the SPI formula and does not describe the distribution of groundwater level properly, was replaced with the empirical distribution. In this way a new tool with the advantages inheritedfrom its progenitor was defined to assess the intensity of drought in groundwater. The new index has all needed attributes to be used to interpret the current hydrogeological situation on both regional and local scales. It can compete with indicators currently used for this purpose in Poland and abroad. The "new standardized groundwater level index” was applied to analyse the course of a groundwater drought that occurred in Poland in recent years (2015-2016).
EN
The article contains descriptive statistics on rainfall in an area of the southern part of the last ice age in Europe, and which now comprises the north-eastern part of the Poland. The study covers the period of 1981-2010. The sums of the annual and monthly precipitation were calculated, while years and months were evaluated in relation to the multi-annual and monthly averages. The frequency of daily precipitations was also determined. Values of SPI (Standarized Precipitation Index) were calculated together with the values of the Selianinov Index, which measures the environmental aspect of precipitation. The average annual rainfall showed a spatial heterogeneity in the region from 700.1 mm (Elblag in the north-west) to 555.3 mm (Mława) in the east and south-east. The greatest precipitation occurred in the last decade of the analysed period of thirty years. However, statistical analysis shows no significant trend change in precipitation during this period. The number of years with sums of precipitation below 75% of the normal turned out to be very small. In the annual cycle, summer precipitation prevailed. On a monthly basis, the averages sometimes exceeded the multiyear averages by as much as 200%, while extreme lows in monthly precipitation reached levels below 25% of the long-term averages. The calculated value of the SPI indicated that the most common drought conditions occurred in May and June; such droughts did not occur in April and July. The Selianinov Index indicates that the least favorable hydrothermal conditions occur in April and May, while the most favorable conditions occur in August and September.
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