The gullied systems from the Falciu Hills within the Chioara catchment (2997 ha) consist of both main types of gullies, discontinuous and large continuous ones along valley bottoms, and lots of ephemeral gullies. Several methods have been used to measure and estimate gully characteristics. Then, the gully development stages, the effect of the natural conditions, and especially the impact of land management on gullying in the Falciu Hills over the last two centuries have been defined. In addition, the role of gully erosion in triggering landslides has also been studied. Two main periods have been distinguished (until 1960 and 1961–2012) for assessing major characteristics of land degradation. The results show that total gully area in the Chioara catchment is 66.4 ha excepting for the ephemeral gullies, and areas occupied by gullies from the five study sub-catchments (2334 ha) account for two-thirds. Total length of the main gully network in the entire catchment is 33.2 km from which the five sub-catchments account for 71 %. The mean gully density of 1.11 km km−2 supports the evidence that here gullying is the major environmental threat. Half of the gully areal growth and three-quarters of the new landslide area occurred over the 1961–2012 period. Delayed deforestation peaking during 1830–1930 and land conversion to arable use resulted in severe soil erosion, high aggradation along the non-gullied valley bottoms, and severe gullying. The average gully head retreat rate over the last two centuries from four trunk continuous gullies is 14 m year−1, and the sediment yield from gullying only accounted for 54–69 % of the sediment mass produced by water erosion. The evolution of gullies is linked to major land-use changes in the study area. Despite a decreasing tendency of gullying and catchment area over the last half century, gullying still remains problematically high in East Romania.
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排序方式： 共有11条查询结果，搜索用时 15 毫秒
1.
Ionita Ion Niacsu Lilian Petrovici Gabriel Blebea-Apostu Ana Maria 《Natural Hazards》2015,79(1):113-138
2.
The present study focuses on the analysis of dryness/wetness conditions in the Danube River catchment area from 1901 to 2013 based on reanalysis data. The spatio‐temporal variability of dryness/wetness conditions is analyzed by means of the Standardized Precipitation Index (SPI) for an accumulation periods of 6 months. To characterize the spatial variability of SPI6 at monthly time scales, an empirical orthogonal function (EOF) analysis was applied. The leading mode of SPI variability captures in‐phase variability of SPI over the entire catchment area of Danube River. The leading mode of dryness/wetness variability was found to be strongly related to the different phases of the Arctic Oscillation. The second and third modes of variability show a more regional character of the dryness/wetness variability over the Danube River catchment area. Based on a composite map analysis, between the time series corresponding to the first three leading modes of dryness/wetness variability and the geopotential height at 850 mb and precipitation totals, it is shown that dryness (wetness) conditions over the Danube catchment area are associated with an anticyclonic (cyclonic) circulation, transport of dry (humid) air towards the Danube catchment area and reduced (enhanced) number of rain days. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
Interannual to decadal summer drought variability over Europe and its relationship to global sea surface temperature 总被引：4，自引：0，他引：4
Interannual to decadal variability of European summer drought and its relationship with global sea surface temperature (SST) is investigated using the newly developed self calibrated Palmer drought severity index (scPDSI) and global sea surface temperature (SST) field for the period 1901–2002. A European drought severity index defined as the average of scPDSI over entire Europe shows quasiperiodic variations in the 2.5–5 year band as well as at 12–13 years suggesting a possible potential predictability of averaged drought conditions over Europe. A Canonical Correlation Analysis between summer scPDSI anomalies over Europe and global SST anomalies reveals the existence of three modes of coupled summer drought scPDSI patterns and winter global SST anomalies. The first scPDSI-SST coupled mode represents the long-term trends in the data which manifest in SST as warming over all oceans. The associated long-term trend in scPDSI suggests increasing drought conditions over the central part of Europe. The second mode is related to the inter-annual ENSO and decadal PDO influence on the European climate and the third one captures mainly the drought pattern associated to Atlantic Multidecadal Oscillation. The lag relationships between winter SST and summer drought conditions established in this study can provide a valuable skill for the prediction of drought conditions over Europe on interannual to decadal time scales. 相似文献
4.
Summary Regional climate model and statistical downscaling procedures are used to generate winter precipitation changes over Romania
for the period 2071–2100 (compared to 1961–1990), under the IPCC A2 and B2 emission scenarios. For this purpose, the ICTP
regional climate model RegCM is nested within the Hadley Centre global atmospheric model HadAM3H. The statistical downscaling
method is based on the use of canonical correlation analysis (CCA) to construct climate change scenarios for winter precipitation
over Romania from two predictors, sea level pressure and specific humidity (either used individually or together). A technique
to select the most skillful model separately for each station is proposed to optimise the statistical downscaling signal.
Climate fields from the A2 and B2 scenario simulations with the HadAM3H and RegCM models are used as input to the statistical
downscaling model. First, the capability of the climate models to reproduce the observed link between winter precipitation
over Romania and atmospheric circulation at the European scale is analysed, showing that the RegCM is more accurate than HadAM3H
in the simulation of Romanian precipitation variability and its connection with large-scale circulations. Both models overestimate
winter precipitation in the eastern regions of Romania due to an overestimation of the intensity and frequency of cyclonic
systems over Europe. Climate changes derived directly from the RegCM and HadAM3H show an increase of precipitation during
the 2071–2100 period compared to 1961–1990, especially over northwest and northeast Romania. Similar climate change patterns
are obtained through the statistical downscaling method when the technique of optimum model selected separately for each station
is used. This adds confidence to the simulated climate change signal over this region. The uncertainty of results is higher
for the eastern and southeastern regions of Romania due to the lower HadAM3H and RegCM performance in simulating winter precipitation
variability there as well as the reduced skill of the statistical downscaling model. 相似文献
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7.
Multidecadal variability of summer temperature over Romania and its relation with Atlantic Multidecadal Oscillation 总被引：1，自引：0，他引：1
Monica Ionita Norel Rimbu Silvia Chelcea Simona Patrut 《Theoretical and Applied Climatology》2013,113(1-2):305-315
We investigate the multidecadal variability of summer temperature over Romania as measured at 14 meteorological stations with long-term observational records. The dominant pattern of summer temperature variability has a monopolar structure and shows pronounced multidecadal variations. A correlation analysis reveals that these multidecadal variations are related with multidecadal variations in the frequency of four daily atmospheric circulation patterns from the North Atlantic region. It is found that on multidecadal time scales, negative summer mean temperature (TT) anomalies are associated with positive sea level pressure (SLP) anomalies centered over the northern part of the Atlantic Ocean and Scandinavia and negative SLP anomalies centered over the northern part of Africa. It is speculated that a possible cause of multidecadal fluctuations in the frequency of these four patterns are the sea surface temperature (SST) anomalies associated to the Atlantic Multidecadal Oscillation (AMO). These results have implications for predicting the evolution of summer temperature over Romania on multidecadal time scales. 相似文献
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9.
Henny A.J. Van Lanen Gregor Laaha Daniel G. Kingston Tobias Gauster Monica Ionita Jean‐Philippe Vidal Radek Vlnas Lena M. Tallaksen Kerstin Stahl Jamie Hannaford Claire Delus Miriam Fendekova Luis Mediero Christel Prudhomme Ekaterina Rets Renata J. Romanowicz Sébastien Gailliez Wai Kwok Wong Mary‐Jeanne Adler Veit Blauhut Laurie Caillouet Silvia Chelcea Natalia Frolova Lukas Gudmundsson Martin Hanel Klaus Haslinger Maria Kireeva Marzena Osuch Eric Sauquet James H. Stagge Anne F. Van Loon 《水文研究》2016,30(17):3097-3104
10.
Climate Dynamics - Variations of the global sea level pressure (SLP) field reflect atmospheric and oceanic influences and have a profound influence on temperature, precipitation and the global... 相似文献
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