Kazimierz Banasik

Mapping monthly rainfall erosivity in Europe

Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part of Britain and Ireland) in May and the highest values are registered during summer months. Starting from September, R-factor has a decreasing trend. The mean rainfall erosivity in summer is almost 4 times higher (315 MJ mm ha− 1 h− 1) compared to winter (87 MJ mm ha− 1 h− 1). The Cubist model has been selected among various statistical models to perform the spatial interpolation due to its excellent performance, ability to model non-linearity and interpretability. The monthly prediction is an order more difficult than the annual one as it is limited by the number of covariates and, for consistency, the sum of all months has to be close to annual erosivity. The performance of the Cubist models proved to be generally high, resulting in R2 values between 0.40 and 0.64 in cross-validation. The obtained months show an increasing trend of erosivity occurring from winter to summer starting from western to Eastern Europe. The maps also show a clear delineation of areas with different erosivity seasonal patterns, whose spatial outline was evidenced by cluster analysis. The monthly erosivity maps can be used to develop composite indicators that map both intra-annual variability and concentration of erosive events. Consequently, spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be applied in different seasons of the year.

Curve Number Estimation for a Small Urban Catchment from Recorded Rainfall-Runoff Events

Abstract Runoff estimation is a key component in various hydrological considerations. Estimation of storm runoff is especially important for the effective design of hydraulic and road structures, for the flood flow management, as well as for the analysis of land use changes, i.e. urbanization or low impact development of urban areas. The curve number (CN) method, developed by Soil Conservation Service (SCS) of the U.S. Department of Agriculture for predicting the flood runoff depth from ungauged catchments, has been in continuous use for ca. 60 years. This method has not been extensively tested in Poland, especially in small urban catchments, because of lack of data. In this study, 39 rainfall-runoff events, collected during four years (2009–2012) in a small (A=28.7 km2), urban catchment of Służew Creek in southwest part of Warsaw were used, with the aim of determining the CNs and to check its applicability to ungauged urban areas. The parameters CN, estimated empirically, vary from 65.1 to 95.0, decreasing with rainfall size and, when sorted rainfall and runoff separately, reaching the value from 67 to 74 for large rainfall events.

Rainfall Erosivity for East and Central Poland

The universal soil loss equation (USLE) and various erosion, sediment yield and water quality models are being used to develop soil conservation programs and identify optimum management practices. Rainfall erosivity is a key input parameter to the USLE and many of the models. The procedure for estimating erosivity, based on rainfall characteristics, investigated in the USA, is often adopted in other regions. Rainfall erosivity has been calculated for nine stations in east and central Poland from long term rain gauge data. The average annual erosivity at the analyzed stations is between 42.6 in north-east and 96.8 [(MJ/ha)·(cm/h)] in south of Poland. From c.64-75% of the erosion hazard occurs during the summer months, June-August.

Effectiveness of Straw Mulch on Infiltration, Splash Erosion, Runoff and Sediment in Laboratory Conditions

Abstract Mulches have extraordinary potential in reducing surface runoff, increasing infiltration of water into the soil and decreasing soil erosion. The straw mulches as a biological material, has the ability to be a significant physical barrier against the impact of raindrops and reduce the detachment of soil aggregates. The present study is an attempt to determine the efficiency of straw mulch as conservation treatment in changes in the splash erosion, time-to-runoff, runoff coefficient, infiltration coefficient, time-to-drainage, drainage coefficient, sediment concentration and soil loss. The laboratory experiments have been conducted for sandy-loam soil taken from deforested area, about 15 km of Warsaw west, Poland under lab conditions with simulated rainfall intensities of 60 and 120 mmh–1, in 4 soil moistures of 12, 25, 33 and 40% and the slope of 9%. Compared with bare treatments, results of straw mulch application showed the significant conservation effects on splash erosion, runoff coefficient, sediment concentration and soil loss and significant enhancement effects on infiltration and drainage. The results of Spearman-Rho correlation showed the significant (p < 0.05) correlation with r = –0.873, 0.873, 0.878 and 0.764 between rainfall intensity and drainage coefficient, downstream splash, sediment concentration and soil loss and with r = –0.976, 0.927 and –0.927 between initial soil moisture content and time-to-runoff, runoff coefficient and infiltration coefficient, respectively.

Conceptual model of sedimentgraph from flood events in a small agricultural watershed

Conceptual model of sedimentgraph from flood events in a small agricultural watershed A procedure for predicting the sediment graph (i.e. the suspended sediment flux), from a small river catchment by heavy rainfall, has been developed using the concept of an instantaneous unit hydrograph (IUH) and dimensionless sediment concentration distribution (DSCD). A formula for instantaneous unit sedimentgraph (IUSG) is presented, and a procedure for estimating the sediment routing coefficient, which is a key parameter of the IUSG, based on measured data of rainfall-runoff-suspended sediment is applied. Field data from a small, field sized agricultural basin, lacated in center of Illinois has been used for analizing lag times for runoff (LAG) and sediment yield (LAGs). Assumptions about sediment generated during rainfall events are discussed. Model koncepcyjny sedymentogramu wezbrañ powodziowych w małej zlewni znaczania sedymentogramów wezbrañ wywołanych ulewnymi deszczami w małej zlewni rolniczej. Procedura zawiera sposób wyznaczania chwilowego sedymentogramu jednostkowego (IUSG), utworzonego z chwilowego hydrogramu jednostkowego (IUH) i bezwymiarowej funkcji koncentracji rumowska unoszonego (DSCD). Przedstawiono zależność na określanie nowo wprowadzonego parametru IUSG, na podstawie czasów opóźnienia odpływu wody (LAG) i odpływu rumowiska (LAGs). Dane pomiarowe z małej zlewni rolniczej (o powierzchni 2,31 ha), położonej w centralnej części stanu Illinois wykorzystano do zbadania zależności czasów opóźnienia odpływów wody i rumowiska. Przedstawiono także różne założenia o wytwarzaniu rumowiska w zlewni w trakcie trwania opadu.

Probabilistic Properties of a Curve Number: A Case Study for Small Polish and Slovak Carpathian Basins

The proper determination of the curve number (CN) in the SCS-CN method reduces errors in predicting runoff volume. In this paper the variability of CN was studied for 5 Slovak and 5 Polish Carpathian catchments. Empirical curve numbers were applied to the distribution fitting. Next, theoretical characteristics of CN were estimated. For 100-CN the Generalized Extreme Value (GEV) distribution was identified as the best fit in most of the catchments. An assessment of the differences between the characteristics estimated from theoretical distributions and the tabulated values of CN was performed. The comparison between the antecedent runoff conditions (ARC) of Hawkins and Hjelmfelt was also completed. The analysis was done for various magnitudes of rainfall. Confidence intervals (CI) were helpful in this evaluation. The studies revealed discordances between the tabulated and estimated CNs. The tabulated CNs were usually lower than estimated values; therefore, an application of the median value and the probabilistic ARC of Hjelmfelt for wet runoff conditions is advisable. For dry conditions the ARC of Hjelmfelt usually better estimated CN than ARC of Hawkins did, but in several catchments neither the ARC of Hawkins nor Hjelmfelt sufficiently depicted the variability in CN.

Streamflow droughts and probability of their occurrence in a small agricultural catchment

Streamflow droughts and probability of their occurrence in a small agricultural catchment The goal of this work consists in quantitative analysis of the occurrence of droughts and their occurrence probability estimated for a small agricultural catchment on the basis of a multi-annual series of daily streamflows in the Zagożdżonka river at the Płachty Stare gauging station, in the context of observed changes in the stream regime during the multi-annual period 1963-2010. The Zagożdżonka river catchment is one of a few in Poland, with long-term records on rainfall and runoff. To identify streamflow droughts in daily discharge hydrograms, truncation level Q90% (discharge determined from the flow duration curve) was used. Minimum duration of drought amounting to 10 days, was the additional criterion for identification of droughts. The Nizowka2003 model was used for finding distributions of the probability of deficit volume and duration of maximum summer droughts for the Zagożdżonka river. The droughts in the small agricultural catchment under study concern only summer half-years and most often they are of short duration - up to 20 days. Longer droughts, lasting lightly over 2 months, can be expected - once per 10 years. The occurrence of a summer drought lasting almost all the season in the Zagożdżonka river is probable once per 100 years. A weak correlation between the minimum drought discharge and their duration was found. Niżówki i prawdopodobieństwo ich występowania w małej zlewni rolniczej Celem pracy jest ilościowa analiza występowania zjawiska niżówki i prawdopodobieństwa jej występowania w małej zlewni rolniczej, na podstawie długoletniej serii obserwacji przepływów dobowych rzeki Zagożdżonki w profilu Płachty Stare, w kontekście śledzenia zmian w reżimie rzeki w wieloleciu 1963-2010. Zlewnia rzeki Zagożdżonki jest jedną z kilku w Polsce, która posiada długi ciąg pomiarów wartości opadów i odpływu. Na potrzeby wyznaczenia niżówek na hydrogramach dobowych przepływów użyto poziomu odcięcia Q90% (przepływ odczytany krzywej czasów trwania przepływów). Dodatkowym kryterium w wyodrębnieniu niżówek zastosowano minimalny czas trwania zjawiska wynoszący 10 dni. Do wyznaczenia rozkładów prawdopodobieństwa objętości deficytu i czasu trwania niżówek maksymalnych letnich dla rzeki Zagożdżonki użyto programu Nizowka2003. Niżówki w rozpatrywanej małej rolniczej zlewni dotyczą jedynie półrocza letniego i najczęściej trwają krótko - do 20 dni. Raz na 10 lat można spodziewać się niżówek dłuższych, trwających niewiele ponad 2 miesiące. Raz na 100 lat jest prawdopodobne wystąpienie w rzece Zagożdżonce niżówki letniej trwającej prawie przez cały sezon. Pomiędzy minimalnym przepływem niżówek a ich czasem trwania uzyskano słabą zależność.

Recorded lag times of snowmelt events in a small catchment

Recorded lag times of snowmelt events in a small catchment The hydrological and meteorological data collected in small, lowland catchment during snowmelt floods have been used to calculate lag time of runoff (Lag) and lag time of sediment yield (Lags). Both, Lag and Lags are important characteristics of the instantaneous unit hydrograph (IUH) and instantaneous unit sedimentgraph (IUSG). Field data from Zagożdżonka River catchment have been used to demonstrate the relationship between lag times. The results of investigation show that: a) there is a strong relationship between Lag and Lags; b) in most cases the value of a = Lags/Lag is smaller than 1; c) in case of snowmelt floods there was only poor correlation between parameter a and the total runoff depth (water supply). Zarejestrowane czasy opóźnienia wody i rumowiska podczas wezbrań roztopowych w małej zlewni Czas opóźnienia odpływu wody (Lag) oraz czas opoźnienia odpływu rumowiska (Lag,s) są ważnymi charakterystykami chwilowego hydrogramu jednostkowego - IUH oraz chwilowego sedymentogramu jednostkowego - IUSG. Ich znajomość pozwala na wyznaczenie tzw. parametru transportu rumowiska B, będącego kluczowym parametrem IUSG. Badania prowadzono w małej, nizinnej zlewni rzeki Zagożdżonki, położonej 100 km na południe od Warszawy. Analizie poddano 22 fale roztopowe odnotowane w okresie 1998-2009. Wykorzystując dane pomiarowe ze stacji badawczej w Czarnej, dla wszystkich fal obliczono czasy opóznienia odpływu wody, a dla 14 spośród ww. fal, dla których posiadano komplet danych, obliczono także czasy opóznienia odpływu rumowiska. We wszystkich przypadkach czas opóźnienia odpływu rumowiska był mniejszy niż czas opóźnienia odpływu wody, co oznacza, że kulminacja fali rumowiska następowała przed kulminacją fali odpływu wody. Stosunek wartości Lags do Lag zawierał się w przedziale 0.41-0.98; wartość średnia wyniosła 0.79; odchylenie standardowe 0.17. Dla wszystkich analizowanych zdarzeń stosunek Lags do Lag był mniejszy od 1.

Probable annual floods in a small lowland river estimated with the use of various sets of data

Probable annual floods in a small lowland river estimated with the use of various sets of data The results of estimation of the probable annual flood flows with the use of various sets of data from a small agricultural lowland river are presented. The traditional statistical series are formed from the annual maximum (AM) flows of hydrological years. After examination of the homogeneity of the series, two sets of data were formed (AM1 of 34 elements and AM2 of 40 elements), which differed in the significance level of one of the stationary tests. The other series for flood frequency analysis has been formed by selecting peaks over threshold discharges (POT). A computer program, developed by IMGW (Institute of Hydrology and Water Management), and spreadsheet were applied for frequency analysis with the use of AM series and POT series, respectively. Results of computations with the use of AM1 and AM2 data indicate for nonsignificant differences in probable flood flows, and significant with the probable flood flow estimated with the POT data. Powodzie prawdopodobne w małej rzece nizinnej określone przy wykorzystaniu różnych zbiorów danych Na podstawie 40-letniego ciągu przepływów dobowych zarejestrowanych w profilu Płachty Stare na Zagożdżonce (A = = 82,4 km2) utworzono zbiory danych do analizy częstotliwości przepływów powodziowych. Po statystycznej analizie jednorodności rocznych przepływów maksymalnych utworzono dwa zbiory AM1 i AM2 (annual maxima), odpowiednio 34- i 40-elementowe, różniące się poziomem zgodności jednego z testów stacjonarności ciągów. Trzeci zbiór danych utworzono ze wszystkich wezbrań okresu 40-letniego, nie mniejszych niż NWQ. Obliczenia wykonano stosując do zbiorów AM1 i AM2 program komputerowy IMGW, identyfikujący dla obydwu zbiorów rozkład logarytmiczno-normalny (spośród czterech) jako najbardziej zgodny z danymi pomiarowymi. Analizę trzeciego zbioru danych (zawierajacych 261 przepływów) przeprowadzono przy wykorzystaniu arkusza kalkulacyjnego. Na podstawie wyników obliczeń stwierdzono znikome różnice w wartościach przepływów maksymalnych prawdopodobnych przy wykorzystaniu zbiorów AM1 i AM2 oraz znaczne różnice w porównaniu z wartościami uzyskanymi przy wykorzystaniu trzeciego zbioru danych.

Effects of rain intensity and initial soil moisture on hydrological responses in laboratory conditions

Abstract Although the possibility of measuring and analysing all parts of the rainfall, infiltration, runoff, and erosion process as a natural hydrologic cycle in field conditions is still one of the more unattainable goals in the hydrological sciences, it can be accomplished in laboratory conditions as a way to understand the whole process. The initial moisture content is one of the most effective factors on soil infiltration, runoff, and erosion responses. The present research was conducted on a 2 m2 laboratory plot at a slope of 9% on a typical sandy-loam soil. The effects of the initial soil moisture content on the infiltration, runoff, and erosion processes were studied at four levels of initial soil moisture content (12, 25, 33, and 40 volumetric percentage) and two rainfall intensities (60 and 120 mm h-1). The results showed a significant (p ≤ 0.05) correlation between rainfall intensity and downstream splash, with r = 0.87. The results reflected the theory of hydrological responses, showing significant (p ≤ 0.05) correlations with r =-0.93, 0.98, -0.83, 0.88, and 0.73 between the initial soil moisture content and the time-to-runoff, runoff coefficient, drainage as a part of the infiltrated water, downstream splash, and total outflow sediment, respectively.