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Assessment of soil erosion models for predicting soil loss in cracked vegetated compacted surface layer

Bora Manash Jyoti, Bordoloi Sanandam, Pekkat Sreeja, Garg Ankit, Sekharan Sreedeep, Rakesh Ravi Ranjan

Acta Geophysica

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2022

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Vol. 70, no 1

333--347

EN

Rainfall-induced progressive soil erosion of compacted surface layer (SL) impedes the functioning of cover system (CS) of landfills with high expected design life (≈ 100 years). The existing soil erosion models are not tested extensively for compacted soil with cracks and vegetation. This study evaluated the efficacy of three popular soil erosion models for estimating the soil loss of compacted SL of CS, which is useful for annual maintenance. The interactive effect of rainfall, vegetation and desiccation cracks on erosion of compacted surface layer was investigated under the influence of both natural and simulated rainfall events for one year. Among all, the Morgan, Morgan and Finney (MMF) model was found to be effective in predicting soil erosion of compacted SL. However, the MMF model overestimated soil erosion when the vegetation cover exceeded 60%. The soil loss estimated from Revised Universal Soil Loss Equation (RUSLE) and Water Erosion Prediction Project (WEPP) models was poor for high rainfall intensity (100 mm/h). The RUSLE and WEPP model overestimated the soil erosion for low vegetation cover (≤3%) and underestimated for vegetation area>3%. The mechanism of root reinforcement, strength due to root water uptake-induced soil suction and its effect on soil loss mitigation could not be adequately captured by the existing models for compacted SL. Further studies are needed to improve the existing erosion models for incorporating the effects of desiccation and vegetation on soil loss from the compacted SL.

2

A single scaling parameter as a first approximation to describe the rainfall pattern of a place: application on Catalonia

Casas-Castillo M. C., Llabrés-Brustenga A., Rius A., Rodríguez-Solà R., Navarro X.

Acta Geophysica

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2018

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Vol. 66, no. 3

415--424

EN

As well as in other natural processes, it has been frequently observed that the phenomenon arising from the rainfall generation process presents fractal self-similarity of statistical type, and thus, rainfall series generally show scaling properties. Based on this fact, there is a methodology, simple scaling, which is used quite broadly to find or reproduce the intensity–duration–frequency curves of a place. In the present work, the relationship of the simple scaling parameter with the characteristic rainfall pattern of the area of study has been investigated. The calculation of this scaling parameter has been performed from 147 daily rainfall selected series covering the temporal period between 1883 and 2016 over the Catalonian territory (Spain) and its nearby surroundings, and a discussion about the relationship between the scaling parameter spatial distribution and rainfall pattern, as well as about trends of this scaling parameter over the past decades possibly due to climate change, has been presented.

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Zmiany intensywności opadów w Hornsundzie (Spitsbergen) w okresie 1978-2008

Łupikasza E.

Problemy Klimatologii Polarnej

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2009

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nr 19

169-188

PL

Artykuł porusza problematykę zmian intensywności opadów atmosferycznych w Hornsundzie (Spitsbergen) w okresie 1979-2008. Szczegółową analizę opadów dobowych przeprowadzono w przedziałach/ klasach kwantyli równych sum opadów, które wyznaczono metodą zaproponowaną przez Karla i in. (1995) oraz Karla i Knighta (1998), a zmodyfikowaną przez Osborna i in. (2000), Brunettiego i in. (2001) oraz Brunettiego (2004). Wydzielone klasy kwantyli sum opadów zawierają w sobie łączną informację o sumie i liczbie dni z opadem, dzięki czemu zostały uznane za uproszczony wskaźnik intensywności opadów. Dla każdego z wydzielonych wskaź-ników intensywności, obliczono tendencje udziału opadów w całkowitej sumie rocznej oraz w sumach półroczy i sezonów. W Hornsundzie, w okresie 1979-2008 istotne trendy wzrostowe intensywności opadów zaobserwowano jedynie w okresie rocznym, w półroczu chłodnym oraz jesienią. W pozostałych porach roku oraz w półroczu ciepłym tendencje były nieistotne statystycznie, chociaż na wiosnę zaznaczył się spadek intensywności opadów.

EN

This paper deals with problems of temporal changes in distribution of precipitation intensity in Hornsund (Spitsbergen) in the period 1979-2008. Trends in precipitation totals, number of days with precipitation and average daily precipitation amount were calculated in order to assess general changes in precipitation intensity. Detailed analysis of changes in distribution of daily precipitation amount was conducted by categorizing all daily precipitation into 10 classes of precipitation intensity and then computing the proportion of each seasonal total which was provided by events of each class. This class intervals, which can be thought of as 10 equal amount quantiles, were calculated after Osborn et al. (2000). In the next step trends in contribution of each precipitation intensity class-interval to annual and seasonal (warm and cool half-year, spring, summer, autumn, winter) precipi-tation total were calculated. Linear regression fitted by the least square method was used to assess trends magnitude and direction. Trends were expressed in percentage of average indices values for the 1979-2008 period (relative trends) which enabled the comparison of the trends magnitude calcu-lated for indices expressed with different units and for class-intervals characterized by various range of daily precipitation amounts. Statistical significance of trends was checked by Mann-Kendall test. Trends with significance level p between 0.2 and 0.1 were recognized as slightly significant whereas trends with p equal to or less than 0.1 were recognized as significant. The 1979-2008 period was the base for trend analysis. Moreover, several arbitrary selected long-term periods (1979-00, 1979-01, 1979-02, …, 1979-08) were also considered in order to assess the trends stability. In Hornsund in the period 1979-2008 significant changes in daily precipitation intensity appeared on annual basis as well as in cool half year and in autumn. There was a significant increase in annual precipitation total and no sign of any changes in the number of days with precipitation. These were a result of an increase in contribution of extreme precipitation (K10) to total annual precipitation and a decrease in contribution of daily precipitation of low intensity. Similar pattern of precipitation intensity changes was noted in cool half year. In this case the changes are a consequence of decreasing trends in contribution of lower intensity class-intervals (K1, K2 I K4) to total precipitation. In autumn statistically significant were increasing trends in precipitation totals, number of days with precipitation and average daily precipitation amounts – at the same time the increases in precipitation totals and average precipitation amounts were much more higher than in the number of days with precipitation. These changes were a result of decreasing trends in contribution of K1, K2 and K3 intensity classes and increasing trends in contribution of K7 and K8 intensity classes in total autumn precipitation. In spring statistically significant drop in precipitation totals accompanied by unchanged number of days with precipitation indicates the decrease in precipitation intensity. However, detailed analysis of trends in contribution of class-intervals to total winter precipitation has not proven any significant changes of precipitation intensity in this season. It is worth to notice that there were negative trends in contribution of majority of precipitation intensity class-intervals to total spring precipitation which probably resulted in significant decrease in intensity of total precipitation. It also should be mentioned that there are opposite trend directions in spring and autumn precipitation totals. In Hornsund the relationships between precipitation and atmospheric circulation depend on daily precipitation intensity. In majority of seasons daily precipitation of the least intensity (class-interval K1) are the most frequent during an inflow of air masses form east under influence of low pressure system. Precipitation form K4 and higher intensity classes were usually noted in SWc type. It must be said that the results of this study are probably influence by well-known problem of precipitation measu-rement errors in polar regions especially in relation to snow and cool period of year.