Impact of Drought on the Productivity of Agricultural Crops Within the Oltenia Plain, Romania
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ISSN 0354-8724 (hard copy) | ISSN 1820-7138 (online) Impact of drought on the productivity of agricultural crops within the Oltenia Plain, Romania Irina OntelA*, Alina VladutB Received: October 11, 2014 | Revised: January 27, 2015 | Accepted: February 26, 2015 Abstract The purpose of this study was to evaluate the effect of moisture conditions on the productivity of agri- cultural crops within the Oltenia Plain, Romania at various time scales. The agro-databases contain the productions of winter wheat, maize and sunflower reported by the National Institute of Statistics and Agricultural Department for the period 1971-2013. The meteorological elements used were represent- ed by the rainfall amount and air-temperature recorded at the six meteorological stations: Drobeta-Tur- nu Severin, Calafat, Băilești, Bechet, Craiova, Caracal and Turnu-Magurele. According to the SPI and De Martonne Index, the driest years, with low rainfall amounts, were 1983-1985, 1993, 2000, 2002, 2007 and 2012, with different degrees of water deficit. Moreover, the years with the lowest productions were recorded in the last half of the analysed period: 1993, 1996, 2000, 2002, 2007 and 2012. The impact of the drought variability of yield on the agricultural crops was evaluated using Bravais-Pearson correla- tions test, which was statistically significant in the last half of the reference period, while the correla- tion in the first half of the period it was not statistically significant. This result can be explained by the political system and the gradual degradation of the irrigation system, which determined the addiction on climatic conditions after ‘89 years. Key words: drought, SPI, De Martonne Index, crops yield, Oltenia Plain, Romania. Introduction billion in economic losses and €1.5 billion in 2007, in Climate change manifests through increasing aver- Greece, Moldava and the rest of the Southeastern Eu- age temperature and changing rainfall regime and it rope. Crop failure was widespread, forest fires raged has many negative effects, both globally and region- and tourists deserted holiday spots in droves, put off ally. The study of drought is very important in terms by water restrictions, scorched landscapes and record of the potential impact on the environment, econo- temperatures (Demuth, 2009). my and food security. According with Lobell, et al. In Europe, many studies about the impacts of cli- (2011), changes in temperature have caused reduction mate on agriculture have been made in the last dec- in global yields of maize and wheat by 3.8 and 5.5% ade (Olesen, Bindi, 2002; Parry, et al., 2004; Roun- respectively from 1980 to 2008. This was relative to sevell, et al., 2005; Maracchi, et al., 2005; Berry, et a counterfactual without climate change. WMO as- al., 2005; Iglesias, et al., 2009, 2011; Potop, 2011; Holz- serts that between 1976 and 2006 the number of are- kämper, et al., 2011; Gobin, 2012). All these studies and as and people affected by droughts went up by almost Climate Crop model, which estimates the combined 20%. In 2003, Europe experienced its warmest sum- effects of projected changes in temperature, rainfall mer since the records began, resulting in about €12 as well as CO2 concentration across Europe, consider- A University of Bucharest, Faculty of Geography, Nicolae Bălcescu Av., No.1, postcode 010041, sect.1, Bucharest, Romania B University of Craiova, Departament of Geography, St. A. I. Cuza, No.13, postcode 200585, Craiova, Romania * Corresponding author: Ontel Irina, e-mail: [email protected] Geographica Pannonica • Volume 19, Issue 1, 9-19 (March 2015) 9 Impact of drought on the productivity of agricultural crops within the Oltenia Plain, Romania Figure 1. Projected changes in water-limited crop yield Source: Internet 1 ing certain management changes thus incorporating 1), in the South of Romania, there have been projected effects of adaptation (European Environment Agen- changes in water-limited crop yield, between -5 and 5 % cy, 2014), confirm that the cereal productivity trends in the south-eastern part of the country and between -5 are increasing in north-western Europe, in Scandi- and -15 % in the south-western part. navia and decreasing in the Mediterranean region This paper presents the impact of drought on the and south-eastern Europe, which will require adap- crop yield within Oltenia Plain, which was observed tation to new climatic conditions (Figure 1). Accord- between two political periods, 1971-1989 and 1990- ing to IPCC WGII AR5, 2014, there is medium con- 2013. The changes of the political system after `89 de- fidence that climate trends have negatively affected termined the appearance of some negative effects like wheat and maize production for many regions (medi- fragmentation of farming land and degradation of ir- um evidence, high agreement). There is also high con- rigation systems, which made the crops more vulner- fidence that warming has benefitted crop production able to drought phenomenon. in some high-latitude regions, such as Northeast Chi- na or the United Kingdom (Jaggard, et al., 2007, Supit, et al., 2010; Chen, et al., 2010; Gregory, Marshall, 2012, Methods and data cited by IPCC WGII AR5, 2014). There are many methods for quantify the drought phe- In Romania, the impact of climate on the agriculture nomenon – Palmer Drought Severity Index (Palm- was studied by Sandu et al., 2010, Mateescu and Alex- er, 1965), Crop Moisture Index (Palmer, 1968), Deciles andru, 2010, which show that the winter wheat can ben- (Gibbs, Maher, 1967), Percent of normal (Willeke, et al., efit from the interaction between increased CO2 con- 1994), Standardized Precipitation Index (McKee, et al., centrations and higher air temperatures, while maize 1993), which have a high or low degree of complexity. In is vulnerable to climate change, mainly in the case of a this study, there were used Standardized Precipitation scenario predicting hot and droughty conditions. Ac- Index (SPI) and Aridity Index of E. de Martonne (IM), cording the ClimateCrop model for the 2050s com- based on precipitation and temperature data registered pared with 1961-1990 for 12 different climate models at seven weather stations (Calafat, Bailesti, Bechet, Tur- projections under the A1B emission scenario (Figure nu Magurele, Caracal, Craiova and D.T.Severin) from 10 Geographica Pannonica • Volume 19, Issue 1, 9-19 (March 2015) Irina Ontel, Alina Vladut Figure 2. The agricultural regions within Oltenia Plain, Romania 1961 to 2013. According to the distance between the ad- The Standardized Precipitation Index (SPI) is one ministrative territorial units (ATU) and weather sta- of the most commonly used indicators of meteorolog- tions, there were delineated seven agricultural subre- ical drought monitoring (McKee, et al. 1993; Hayes, et gions (Figure 2, Table 1) and it was calculated the crops al., 1999; Paltineanu, 2008; Potop, 2011), which can be yield for each subregion in order to establish the rela- established for each time scale (1, 3, 6, 12 months, etc.). tionship between climate conditions from each weath- According with Edwards, McKee, 1997, the SPI in- er station and the crops yield. The agricultural data sets volves fitting a gamma probability density function to are represented by winter wheat & rye (the values are a given frequency distribution of precipitation totals cumulated), maize and sunflower reported by the Na- for a climate station. The gamma distribution is de- tional Institute of Statistics (1971-2004) and Agricul- fined by its frequency or probability density function: tural Department for the period 2005-2013. Landsat 1 αβ−−1/x images were used to calculate NDVI, which show the gx()= α xe for x > 0 vegetation growth in the dry years. βαΓ() where α is a shape parameter (α > 0), β is a scale pa- Table 1. The agricultural regions and the weather station rameter (β > 0), x is the precipitation amount (x > 0), within Oltenia Plain and Region No. ATU Weather station ∞ Γ()α = yeα−1 −y dy A1-D.T.Severin 7 D.T.Severin ∫0 A2-Calafat 16 Calafat where Γ(α) is the gamma function. The α and β pa- A3-Bailesti 24 Bailesti rameters of the gamma probability density function A4-Craiova 25 Craiova are estimated for each station, for each time scale of A5-Bechet 19 Bechet interest (3 months, 12 months, 48 months, etc.), and A6-Caracal 29 Caracal for each month of the year. Edwards & McKee (1997) A7-Turnu Magurele 11 Turnu Magurele suggest estimating α and β using the maximum likeli- hood solutions of Thom (1966): Geographica Pannonica • Volume 19, Issue 1, 9-19 (March 2015) 11 Impact of drought on the productivity of agricultural crops within the Oltenia Plain, Romania etation in red. The Landsat images are available at In- ^ 1 4A α =+11+ ternet 3. 4A 3 ^ x = β ^ Results and discussion α where: Assessment of the drought during the vegetation period of crops ∑ln()x Ax=−ln() To highlight the drought event for growing crops pe- n riod it was calculated the Standardized Precipitation n = number of precipitation observations Index (SPI) for 12-months (the end of September), 8-months (the end of May) and 5-months (the end The resulting parameters are then used to find the of August). Besides, the De Martonne Index was cal- cumulative probability of an observed precipitation culated for the summer season because in this peri- event for the given month and time scale for the sta- od high temperature determine increase of the evap- tion in question. The cumulative probability is given otranspiration, which has a negative impact on the by: crops yield of the maize and sunflower. x x ^ ^ As results, the SPI12 registered the lowest values in αβ−−1/x Gx()==gx()dx ^ xedx 1993, between -3.24 (Caracal station) and -1.23 (Drobe- ∫∫α 0 ^ ^ 0 ta Turnu-Severin station); at all meteorological sta- βαΓ () tions it was registered extreme drought, except D.T.