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University of Debrecen (2018)

Comparison analyses of inland water and drought

Titre : Comparison analyses of inland water and drought

Aszály és belvíz jelenségek összehasonlító értékelése

Auteur : University of Debrecen

Université de soutenance :

Grade : Doctor of Philosophy (PhD) 2018

Many of the literature support that regarding the risk of climate change, water-related risks are one of the main threats to agricultural production. In our country, the average of 10 years is regularly 2-3 years appears inland water, while 2-3 years appears drought. They often occur in the same year and in the same region. In the Carpathian Basin. These can become more and more common in the future. During the research I have done tests on drought and inland water in different scale and hydrological locations. The Great Hungarian Plain, Szolnok-Túri Plain, Nyírség and two smaller (arable land, grassland) areas in the North-Nyírség which are close to Nyírbátor were included as sample areas. The aim of my research on drought was to evaluation major drought indices in hydrologically different geographical regions. For the 2002-2012 period, the Ellenberg-Index, the Standardized Precipitation Index (SPI), the Reclamation Drought Index (RDI), and the Pálfai Drought Index (PaDI) were calculated in the sample areas (Szolnok- Túri- Plain, Nyírség) and I investigated the relationships between them. I found that the investigated indices have similar input data but droughts were reported differently in the sampling period. In addition, the NDVI index (Normalized Differential Vegetation Index) were calculated in the sample areas for May and August periods on not irrigated arable lands. I tested the correlations between the NDVI index values and the meteorological index values which showed closer relationship with the NDVI values in August in both sample areas. On the basis of the results of the correlation study I established the relative reliability of drought indices :, which were the following PaDI>>Ellenberg>>SPI- 3>>RDI. Based on the literature I have elaborated that the cathegories of the internationally used drought indeces is not similar to the hungarian indices and drought measurement has no uniform practice, which is occur a problem in comparing different drought phenomenon in national and internation level. Based on the above I found it necessary to create a hybrid drought index that can be used in both national and international practice where the weighting factors were deterministic coefficient values (from the August NDVI values and from the meteorological drought index comparative test). The normalized hybrid index was based on the value of the previously calculated four indexes. During the calculation, I formed the values of the four meteorological indexes (Ellenberg, SPI-3, RDI-3, PaDI) to a scale of 0-1. These values were weighted, cumulated, divided by the number of indices, and then calculated for one percent scale. In the case of the hybrid index from the local meteorological data I found on the Szolnok-Túr Plain that 2002- 2012. I cannot detected drought in three years (2007-2008, 2009-2010, 2010-2011) and extreme droughts were between 2002-2003, 2006, 2006-2007, 2011-2012. There was moderate drought in 2003-2004, 2008-2009 and drought in 2005-2006. 2004-2005 was mild drought year based on the normalized hybrid drought index. In the case of Nyírség, none of the years was drought-free and I cannot detected mild drought during the examined period. There was one year 2010-2011 which belonged to moderate drought category. The 2003-2004, 2004-2005, 2007-2008, 2009-2010 and 2011-2012 years were droughts. In the 2004-2005, 2005-2006, 2006-2007, 2008-2009 years, the extreme drought category were classified according to the normalized hybrid drought index. I also illustratred the values of the normalized hybrid index in the space and as a result of it I could quantify the spatial extent of different drought categories in the Great Hungarian Plain, in Szolnok-Túr Plain and in the Nyírség also. In this case, I downloaded the index values from the CarpatClim database and I did the calculations in the same way as above.

Mots Clés : aszály ; drought ; belvíz ; normalizált hibrid aszályindex, ; inland water ; normalized hybrid drought index ; SAR ; LiDAR ; Növénytermesztési és kertészeti tudományok ; Agrártudományok

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