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Investigation of Transition Possibilities between Drought Classifications Using Standardized Precipitation Index for Wet and Dry Periods – Lower Seyhan Plain, Türkiye Case

Şimşek Serin Değerli, Çapar Ömer Faruk, Turhan Evren

Journal of Ecological Engineering

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2023

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Vol. 24, nr 5

201--209

EN

In this study, the Karaisalı region of Türkiye, which has a semi-arid climate and is known to contain the extensive plains and rich water resources of the Seyhan Basin, was preferred as a study area for investigating wet and drought periods for a long timescale. Forty-one years of total precipitation data, between 1980 and 2020, belonging to the closest precipitation observation station located in the Karaisalı region were used. By using the Standardized Precipitation Index (SPI), which is one of the frequently used meteorological drought indices, drought classification probabilities, expected first transition period and residence time in each drought severity class values were calculated for the 12-month time scale. As a result of the study, it was determined that the most drought period took place in 2012 according to the examined time duration. In addition, the most wet period was observed in 2001. When various time scales were considered, SPI-3 and SPI-6 have Near Normal Wet periods, while SPI-9 and SPI-12 have Near Normal Drought periods. Extremely Wet periods were more numerous, while Extremely Drought periods lasted longer. In addition, 3 months after the end of the drought categories, it can be seen that the Wet and Drought periods change into Near Normal Wet and Near Normal Drought periods.

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Monitoring Land Use and Land Cover Changes Using Remote Sensing Techniques and the Precipitation-Vegetation Indexes in Morocco

Ait El Haj Fatiha, Ouadif Latifa, Akhssas Ahmed

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 1

272--286

EN

The study of land use and land cover change (LULC) is essential for the development of strategies, monitoring and control of the ecosystem. The present study aims to describe the dynamics of land cover and land use, and specially the impact of certain climatic parameters on the distribution of vegetation and land cover. For this study, multi-temporal remote sensing data are used to monitor land cover changes in Morocco, using a set of Landsat images, including Landsat 7 (ETM+), Landsat 5 (TM), and Landsat 8 (OLI), captured during the period 2000–2020, those changes were determined by adopting the maximum likelihood (ML) classification method. The classification results show good accuracy values in the range of 90% (2000), 80% (2007), 82% (2010), 93% (2020). The LU/LC change detection showed a decrease of agricultural and forest areas in the order of 5% between the year 2000 and 2020, and an increase of bare soil of 5% to 6%, and a notable change in urban area from 97.31 ha (0.03%) in 2000 to 2988.2637 ha (0.82%) in 2020. The overall results obtained from LULC show that the vegetation cover of the study area has undergone major changes during the study period. In order to monitor the vegetation status, an analysis of the precipitation-vegetation interaction is essential. The normalized difference vegetation index (NDVI) was determined from 2000 to 2020, to identify vegetation categories and quantify the vegetation density in the Lakhdar sub-basin. The obtained NDVI was analyzed using climatic index SPI (Normalized Precipitation Index) based on rainfall data from five stations. The correlation study between NDVI and SPI indices shows a strong linear relation between these two indicators especially while using an annual index SPI12 however, the use of NDVI index based on remote sensing provides a significant result while assessing vegetation. The results of our study can be used for vegetation monitoring and sustainable management of the area, since it is one of the largest basins in the country.

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Quantification of historical drought conditions over different climatic zones of Nigeria

Ogunjo Samuel, Ife-Adediran Oluwatobi, Owoola Eunice, Fuwape Ibiyinka

Acta Geophysica

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2019

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Vol. 67, no. 3

879--889

EN

The impact of extreme climate such as drought and flooding on agriculture, tourism, migration and peace in Nigeria is immense. There is the need to study the trend and statistics for better planning, preparation and adaptation. In this study, the statistical and temporal variation of climatic indices Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) was computed for eighteen (18) stations covering four climatic zones (Sahel, Midland, Guinea Savannah and Coastal) of tropical Nigeria. Precipitation, minimum and maximum temperature from 1980 to 2010 obtained from the archives of the Nigerian Meteorological Services were used to compute both the SPI and SPEI indices at 1-, 3- 6- and 12-month timescales. The temporal variation of drought indices showed that droughts were more prominent at 6- and 12-month timescales. SPI and SPEI were found to be better correlated at longer timescales than short timescales. Predominant small, positive and significant trend across the region suggest an increasing trend due to climate change.

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Zmienność występowania susz w okresie wegetacyjnym w Polsce w latach 1966-2015

Szyga-Pluta K.

Przegląd Geofizyczny

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2018

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Z. 1-2

51--67

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.

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Adaptacja wskaźnika SPI na potrzeby monitorowania suszy w wodach podziemnych

Kowalczyk A.

Przegląd Geologiczny

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2017

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Vol. 65, nr 11/2

1301--1305

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).