Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 11
Issue 1
Environmental Development
Available Online: http://www.ejpau.media.pl/volume11/issue1/art-12.html


Artur Radecki-Pawlik1, Tomasz Skalski2
1 Water Engineering Department, Environmental Engineering and Geodesy Faculty, Agricultural University of Cracow, Poland
2 Department of Entomology, Institute of Zoology, Jagiellonian University, Cracow, Poland



The paper presents the results of an investigation of bankfull discharge using a proposed IBA method (Invertebrate Bankfull Assessment method). The research was performed in one of the Polish Carpathian streams in the Gorce Mountains region: the Ochotnica Stream. As the index of determination of bankfull volume the size of terrestrial invertebrates (carabids) was advocated which were present in the investigated research cross-section and were resistant to specific water discharge conditions. Thus, three so-called invertebrate benches (levels) were recognised which were characterised by selected specific invertebrate species. Next the discharge values were calculated up to those bench levels employing the proposed IBA method (biotic method) and analysed using Canonical Correspondence Analysis. At the same time bankfull was calculated in classic ways using several methods based on hydrological and geomorphological approaches (abiotic methods) as well as based on the Woodyer method which refers to changes in riparian plant communities and their resistantce to flooding (Woodyer’s method is also biotic). Finally, some of the discharges obtained using the IBA method were recognised as lying within the range of bankfull discharges determined using classic morphometric methods. Consequently, a main aim of the paper is to advocate the proposed IBA method to geomorphologists, hydrologists and river engineers to be used and applied in interdisciplinary studies connected with river management, catchment management and small-scale river training works when the conservation value of the systems should not be overlooked.

Key words: bankfull discharge, mountainous stream, ground beetles, biomass, Polish Carpathian Mountains, IBA method.


As was noted by Petit and Pauguet [31] amongst all the characteristic discharges which need to be taken into consideration in the analysis of the river regime, bankfull discharge is the most important. There are several reasons why this should be the case. Traditionally geomorphologic and hydrological definitions are those which are most frequently quoted in the scientific literature. Bankfull is thus defined as that flow which fills the channel to the tops of the river banks [52]. It is also known as the channel forming discharge [9], the height of the valley floor [27] or finally the elevation of the active floodplain [5,53]. At the same time Wolman [54] and Pickup and Warner [32] define bankfull as the elevation at which the width/depth ratio (W/D) of the river channel cross section becomes a minimum. Leopold and Skibitzke [24] regard bankfull as the elevation of the upper limit of sand-sized particles in the boundary sediment. With the definitions listed above may be termed geomorphologic concepts of bankfull, some scientists use hydrological approaches. For example, Leopold et al. [24] noticed that recurrence interval of bankfull discharges varies between 1 and 2 years, which also was noticed by Dury [14] who subsequently defined it at 1.58 years. At the same time Pickup and Warner [32] note that the bankfull return period of occurrence in the river lie mainly within the range 4-10 on the annual series. But, as it was mentioned by Williams [52] bankfull is something more that just one reference discharges, but rather it marks the conditions of incipient flooding. In this later respect bankfull is also of great interest to river engineers and catchment managers and planners [18,20,27]. If so, in the present view of the Fifth European Water Directive bankfull could be a useful tool which might be used by river engineers, but it is also becoming an important factor for ecologists and biologists since they are interesting in river changes from the point of view of local ecosystems which are located within the corridor of a river. So, nowadays, there are several groups of specialists who have vital interests in defining and quantifying bankfull values in the particular river cross sections, which values, as it was shown by Radecki-Pawlik [36] appears within a rather certain range of discharges in contrast to a single number related strictly to the geometry of the channel cross section. As long as the hydrological and geomorphologic definitions and approaches of bankfull allows in more or less precise ways to predict its range, river engineers prefer to define an upper limit of bankfull to provide a basis to design low-scale river training work structures situated, for example, along river banks to reduce bank erosion.

Thus, very often river engineers select one method to define bankfull based on hydro-geomorphologic assumptions, and this information is considered adequate to start the design of small hydraulics structures and/or embankments. But, as was noted above, given increasing restrictions on the width of river floodplains induced by development in both developed and developing countries as well as restrictions on the river channel itself, and in the time of introducing the Fifth EU Water Directive, river corridor is not only a thing which consists of its “geometry” and “amount of water” which “fills up river channel to the tops of its banks”. Rather the river must be viewed more holistically including a consideration of “ecological” aspects. Woodyer [57] noticed that plants are good indicators for bankfull. Woodyer introduced the “plant bench index method” for Australian rivers. This index could be associated with different stages of water levels including or instead of bankfull and is characterized by specific species present or not present within the research cross section. However, Riley [40] is very careful to allow the location of vegetation to define the bankfull level, preferring his and others morphometric criteria to those preferred by Woodyer. At the same time Radecki-Pawlik [35], shows that within some reaches of Carpathian streams plants could be quite good indicators of bankfull. Also Hey, Thorne and Newson [21] found vegetation to be a useful indicator of bankfull and they introduced four equations related to bankfull parameters based on the presence of cover of trees and shrubs and the percentage of these. Given the above considerations and in the spirit of the philosophy of the Fifth EU Water Framework it seems to that bankfull concept has to consider both biotic and abiotic factors.

Possibly, in those countries where many wild and unregulated rivers still exist in their natural conditions, one can be forgiven for thinking that the biology and ecology within the river corridor is rich and robust. But especially in Poland, where in the Carpathians and also in lowland part of the country, there is an urgent need to rehabilitate many streams and rivers, already engineered, but at the same time there is a requirement to protect people against flooding and the banks of the rivers against the linear erosion. That is a pro-biological or pro-ecological kind of philosophy is now need that integrates the biotic and the abiotic factors.

In this paper a new approach to determine bankfull is presented that utilises biotic factors as well as abiotic factors. The new approach which might be considered as another biotic approach parallel with those based on vegetation and might be used as an important supplementary method to complement already established hydrological and geomorphological abiotic methods. It is acknowledged that all abiotic methods give a quite good approach to defining bankfull when looking at rivers from a morphometric perspective. But in the present world, there is a need to develop a close interdisciplinary cooperation between geomorphologists, hydrologists, river engineers, ecologists and biologists who working together can then protect people against flooding, river banks against bank-erosion and river bed against incision but at the same time to protect as many as possible living organisms and plants within river cross section and river reach. Such cooperation nowadays is not only complementary but will no doubt be increasingly mandatory for many river rehabilitation and renaturalization projects.

The new method for determining bankfull is based on an assay of terrestrial invertebrates that have colonized particular river cross sections. The method is presented in such a way so that any scientist and river engineer could use it with minimal background not only biologists, since the main factor as the main factor to be considered is the size of the body of invertebrates, which all people working with rivers, starting from hydrologists and geomorphologists through river engineers and finishing with biologists could easily assess. Since, as has been pointed out, bankfull value is not a fixed number for a particular river cross-section rather but it could be found within the certain range of carefully found discharges [32,36]. In such understanding the justification of applying proposed here Invertebrate Bankfull Assessment method (called later IBA method) using invertebrate community as biotic indicators especially in places where river bank protection meets the demand of using a small scale river engineering works is a worthy consideration. Such studies are underway and the results will be presented in due course. Rather, here the main idea is introduced for consideration by others who have to take care of river corridors/channel environments. Also it is hoped that others will develop parallel studies to test the idea as well as provide more data to improve its quality.

For the purpose of this study the propose IBA method obtained results were compared and discussed with other bankfull results obtained using methods based on morphometric and hydrological criteria (abiotic method), but also with Woodyer output based on vegetation limits (called here biotic methods). From the Woodyer study the authors of the present study adopted the name “bench” to show in the clearest way the levels to which the water has the influence on changes of terrestrial communities.


The Ochotnica Stream is situated in Polish Carpathians (this part of Carpathians is known as the Gorce Mountains). Some basic physical characteristics of the Ochotnica stream are presented in Table 1.

Table 1. Physical characteristics of the investigated stream


The Ochotnica

Precipitation (mm)


Catchment Area (km2)


Channel Length (km)


Two years flood Q50% (m3 s-1)


Four years flood Q25% (m3 s-1)


Five years flood Q20% (m3 s-1)


Ten years flood Q10% (m3 s-1)


One hundred years flood Q1% (m3 s-1)


D90 (mm)


D50 (mm)


Percentage < 4mm


The Ochotnica is a tributary of the very famous Dunajec River, which is well-known for its geological features (a dip and meandrouss river gorge cut through limestone rock) (Fig. 1). The Ochotnica stream has a quite large catchment area (55 km2) as for its length (12 km). It has the consequence that the Ochotnica is very flashy and experience frequent bedload movement in its braided part of the channel. Geologically the Ochotnica is situated in the Carpathian flysch.

Fig. 1. Location of the Ochotnica Stream

The Ochotnica is an alluvial and braided stream which runs through a flood plain composed of Quaternary and Holocene mudstones and coarse gravel, with occasional Tertiary Paleogenic shales, marls and sandstones (known as the Istebnianskie stratums). The Ochotnica gravel alluvium form a typical framework for that region mountain streams, where the interstices among cobles and pebbles are filled by a matrix of finer sediment. Unfortunately, because of the uncontrolled and illegal mining of gravel in some places from the riverbed, strong channel incision and bank erosion is evident. Because of these disturbances many local scale river engineering works are planned and are in place, which undoubtedly interfere in local river corridor ecology. The research reach of the studied stream is presented in the photos from 1 to 4. The pictures were taken under different yer sesons to show the variety of chcnges of the morphology as well as variety of plants which is important for the applied methodology.

Phot. 1. The Ochotnica Stream research reach in early spring time – April 2004

Phot. 2. The Ochotnica Stream research reach – ealy summer July 2004

Phot. 3. The Ochotnica Stream research reach – very low stages of water in June 2003

Phot. 4. The Ochotnica Stream research reach – the end of the flooding wave in June 2003


Basic bankfull methodology
As was noticed by Werritty [50] – it has long been known that there are empirical relationships between the flow in a channel and its geometry. There are two main ways by which authors define bankfull (they were previously detaily presented in Radecki-Pawlik [36], but here it seems to be valid to outline them again since the new concept of the method is introduced). The first group of definitions describe bankfull in terms of the geometry of a cross-section, the second group of definitions describe it as a bankfull discharge in terms of volume of water. Both groups are here termed abiotic methods. Within this group one can include methods which consist of plotting at a-station hydraulic geometry relations between discharge Q and such flow features as cross-sectional area A, water surface width W, and mean depth D (=A/W) at the cross-section of interest. Bankfull width and/or area are determined from field measurements, and bankfull discharge is read from the appropriate hydraulic geometry graph [36]. Alternatively, a channel cross-sectional survey can provide values of A, W, and D with stage. Stage is plotted against any one of A, W, or D (or W/D), and a break in the trend of plotted points usually identifies bankfull level [8,54]. Wolman suggests that bankfull stage is the stage at which the ratio of channel width to channel depth is at a minimum.

Also an example of the first group of methods is that proposed by Woodyer [57]. Woodyer identifies three river benches – low, middle and high – in terms of the annual maximum series, and uses vegetation cover to verify results. His method may be particularly successful in mountain creeks where plants are abundant. The method identifies the low bench as occurring only at low stage, and usually showing an obvious relationship to the bed of the stream. If exposed, the streambed is not vegetated, or carries only a thin cover of ephemeral grass or herbs. The middle bench occurs where flood frequency is in the range of 1.01-1.21 years. On the middle bench, some larger species of vegetation are present, such as water-tolerant trees. The high bench is the widest and most clearly developed bench, and is characterised by abundant tree cover in a virgin state. At the high bench level, flood frequency varies between 1.24-2.69 years (Fig. 2). The Woodyer method was tested in Polish Carpathians by Radecki-Pawlik [35].

Fig. 2. Definition sketch for the Woodyer method

The second group of methods define bankfull as a bankfull discharge in terms of volume of water. Here the Gauckler-Manning flow equation [32,44] is one of several equations, which can be used directly at a station to determine bankfull discharge with the best fitted roughness coefficients carefully chosen using tables, photos and postulates of Chow [10] and Selby [42]. The equation as presented here is:

Qb = (1.0 / n) Ab Db2/3 S1/2               (1)

The required variables are therefore the resistance coefficient n, the bankfull flow area Ab, the bank-full depth Db, and the water surface slope S. Investigators obtain the resistance coefficient either by estimating bankfull conditions, or by actually measuring a lower discharge, computing the coefficient, and assuming that ‘n’ for the same coefficient applies at bankfull stage. Bankfull geometric properties are determined from a further measurement of cross-sections. When one cross-section is used, the resulting Qb applies to that section only. Qb for a reach can be obtained by using several cross-sections with the slope-area method. In the field, the slope of the energy gradient is often taken as the bed or water surface slope. This should be measured in the field, but is sometimes obtained from a topographic map [52].

Woloszyn’s method of calculating bankfull [55] should also be considered. Woloszyn [55] suggests that the above-mentioned Manning equation should be applied to the highest stream/river terrace, which is easily separated and visualised during field investigations. Finally, Williams [52] proposed an equation for bankfull, after investigating fifty-one different rivers. Williams’ final regression equation was:

Qb = 4.0 Ab1.21 S0.28               (2)

where Qb is in cubic meters per second, Ab is in square meters and S is dimensionless.

Applied methodology Typical alluvial and braided cross-sections situated approximately in the middle of the Ochotnica Stream were chosen and observed within one calendar year. The selected cross-section exhibited a range of characteristics in terms of bank river benches (one, two or three benches), vegetation, and riverbed configuration (flat bed and/or across a river bar). A detailed survey was undertaken using geodesy instruments and field water gauge. Later, hydrological calculations were performed employing Punzet’s formula [34] to find t-years floods. Punzet’s formula, the most appropriate and most commonly used in Poland, was applied employing the WODA-88 computer model [34]. Finally, field measurements were taken and bankfull discharge values were calculated according to the methods of Wolman, Woodyer, Schumm and Brown, Woloszyn and Williams (described above). The plants required to apply Woodyer’s method were identified during the spring, when they are in flower [35,36]. In the case of Woloszyn’s method, all terraces were defined in the field. Bankfull values were then determined. When using Schumm and Brown’s concept, different values of Manning’s n (n=0.02, n = 0.025 and n=0.03) for mountain streams, with gravels, cobbles and few boulders at the channel bed [10,42] were employed. This was done because of the usual subjective assumption of n given by the observer in the field. Here, n was chosen as if for gravel bedded stream, using the maximum and minimum values suggested by Chow (coefficient tables; Chow [10]) and confirmed in the graphs of Selby [42]. For those roughness values, three values of hypothetical bankfull were calculated: minimum, normal and maximum.

Also the morphometric Riley method was used in the study. When applying Riley’s [40] method, the first index BI (the first maximum) was recorded, as well as all local maximums found when calculating step-by-step BI values (Fig. 3)

Riley [40] proposed the bench index BI:



Fig. 3. Definition sketch for the Riley method

where W and D are defined above and i=1.2.3...n-1th measurements. The bench index BI plotted against depth D for decreasing values of depth within a channel shows a marked peak value near the actual bankfull stage.

Invertebrate Bankfull Assessment method (IBA method)
Ground beetles were used in this study and have been frequently used as bio indicators of environmental changes in other studies [37]. They are very abundant in many riparian habitats [1,4,15] in temperate regions. The structure of beetle communities reflects responses to frequency of disturbance. In near-water habitats seasonal flood plays a key role. Different fluctuations of water level at different levels above the benches create more or less favourable conditions for accumulation of food necessary for adult egg laying. Among the adult forms the female need enough time for collection of energetic resources for egg hatching [48]. Here we assume that water flooding occurring more or less frequently causes sustain alteration in abundance of taxa, often resulting in the elimination of some taxa in the favour of less competitive but more adopted species (species turnover). First of all such disturbance eliminates food supplies in the changing environment. In consequence predators should be smaller and with big dispersal power. In general, disturbances often have disproportionately strong negative effects on larger species than on smaller ones [56]. In that case more frequent disturbances provides less food for accumulation, then in consequence only smaller animals can survive and have reproduction success. In natural communities, two main factors: habitat and intraspecific competition play main role in formation of the structure. The most dominant species have the best fitness for a given habitat and competition. In a changing environment there is a specific trade-off between preferences for increase body mass (better competition) and adaptation to changing condition (smaller energetic requirements). Such a relation could be used as a method of assessment of bankfull discharge using the so-called biotic index.

Here is tested the application of ground beetles community structure as a method of assessment of particular level or bench associated with specific t-years flood level and later linked to a bankfull level. Firstly the level of adequate t-year flood is defined and then comparing it with the levels (or range of levels) which were then associated with the presence of specified invertebrates. In the chosen research river cross section twelve localities were chosen that differed in the distance to the base level which in this specific case was a level cut through the point of the highest tawleg altitude. Also in the examined cross section there are three braids which are very characteristic for the morphology of the Ochotnica stream (fig. 4).

Fig. 4. Cross section of the Ochotnica Stream with the location of sample sites

At each localities within the examined cross section ten pitfall traps (plastic cups with 10% of ethylene glycol) were installed. Samples were taken monthly throughout the whole vegetation season. At each locality four samples were taken. Ground beetles were then sorted and preserved in 70% alcohol for further identification. For each locality ground beetles community structure parameters such as total abundance, richness, species diversity and its evenness, body length and biomass were calculated. The instalation of pitfall traps is presented in the photos from 5 to 8.

Phot. 5. The pitfall trap in the gravel bed

Phot. 6. The pitfall trap instalation process

Phot. 7. The pitfall trap instalation on the top of the gravel bar

Phot. 8. The pitfall trap filled up with 10% of ethylene glycol

In most communities the distribution of abundances in size classes is unimodal. Ribeira et al [38] showed that significantly more small species were presented in disturbed habitats. So it is hypothesized that the distribution of particular size group in riverine community will change with frequency of floods. According to Hurka [23] the size of most central European carabid beetles varies between 1-35 mm. Thus in more disturbed habitats the proportion of the smallest toward medium sized beetles will be good predictor and can be applied as a indicator of habitat changes (flood frequency). In this manner it is proposed that the formula of bankfull assessment can be tested in particular example of the Ochotnica stream research cross section in Polish Carpathians:

IBA index = abundance of 1-6 mm specimens/abundance of 18-24 mm specimens

Such a simple index allows anybody to collect species within any cross section, measure them and classify them into size groups. Next heaving the value of the index and the level/altitude of a particular class/community occurrence and also at the same time having the level of the calculated t-year flood for the particular cross section, a bankfull level could be easy to asses from the rating curve.

Application of such formulae was tested by multivariate statistical methods. Principal Component analysis, an indirect multivariate method was chosen to examine the distances between assemblages of beetles and their similarities. Because the distribution of particular species on three benches is not continuous and is not revealed as a Gausian unimodal type, the linear model was applied in such analysis. To examine the relationship between ground beetle assemblages and environmental variables direct gradient analysis, Canonical Correspondence and Redundancy Analyses was applied [46]. To test the species responses, CCA which included unimodal distribution of each species was applied. In case of variation of community parameters RDA (a linear method) seemed to be more suitable. Each multivariate method was chosen according to maximum level of variation described in the analysis.


The distribution of abundances of the communities in different body size classes was assessed and it was found that in the research section – all communities from the first bench have right skewed distribution toward smaller species (Fig. 5). Assemblages, however from the second and third benches, have the most species belonging to medium sized species. In every assemblage from the first bench, the proportion of very small specimens to medium sized is always bigger than 1, meanwhile on the second terrace it is always lower than 1. In the third one there is almost no small body sized specimens at all.

Fig. 5. Relationship between biomass of dominant species in assemblage and location in particular bench

The most abundant species from the community (dominant one) are also the another good method of assessment of each bench. Knowing the density of most abundant species and measuring its length it is possible to calculate the total biomass.

Fig. 6. Distribution of species abundance in size classes for particular carabid assemblage (1-12) located on three benches

As it is shown in Fig. 6, the biomass of dominant species at the research area is growing according to equation y = 147.15 e 1,5239x, (t = 4.72, p = 0.0008), where x is a number of the bench.

After such assessment of the data the IBA index was calculated or all the identified benches. Later bankfull was calculated using all the abiotic methods referred too above. All plant species were identified along our research cross section, and in this manner three river benches were delimited according to Woodyer’s postulates. Finally these benches were associated with the levels at which were placed the invertebrate traps. In this way were calculated the bankfull values also for those two biotic methods.

The results of calculations of bankfull values using all the methods are presented in the Table 2. Characteristic values of bankfull calculated here using introduced IBA methods including the value of IBA indexes for each bench are given in the last column of the Table 2. As long as the identified benches where particular IBA index was characteristic, these benches were compared with those levels of previously identified t-years flood levels. Next are calculated the discharges adequate for IBA benches.

Table 2. Bankfull values for the Ochotnica Stream

Bankfull discharge values in a cross-section within the investigated research reach,
Qb (m3 s-1)
according to different method of calculation





Schumm, Brown and Warner



IBA method
(Invertebrate Bankfull Assessment method)

First terrace


Second terrace




central value 29.80

minimum W/D index


First index value


local index


(Manning’s n=0.02-0.03 range)

n=0.02 minimum
n=0.025 average




High bench


Middle bench


Low bench


Bench 3
IBA index << 1

Bench 2
IBA index ≤ 1
11.10 ÷ 38.40
central value 24.75

Bench 1
IBA index > 1
4.10 ÷ 11.10
central value 7.60

When discussing the obtained value of bankfull discharge for the considered research cross section, as it was postulated by Radecki-Pawlik [36] one should expect it to lie just between values of bankfull discharges which were found using many methods – in the present case by abiotic and biotic methods. At the same time there is a need to have just one value of bankfull to which other values of discharges can be referred in the particular river cross section. Here in the particular case of the Ochotnica stream research cross section there is a need to exclude from consideration some obtained results of bankfull from some of employed methods. Firstly, rejected are the smallest values from the Woloszyn and Woodyer methods since those values are to small to be responsible for any river morphology changes in the context of t-years values showed in the Table 1 as well as because the share stresses which can bed predicted under such discharges are not big enough to initiate entraintment. Also excluded are the local max Riley and Wolman numbers as they seems to be good indicators for bankfull within only one braid channels but when dealing with a multi-braided stream cross section (which we have in the case of the Ochotnica) the values of discharge obtained here with mentioned the two methods are two small. Finally to find the range of discharges where expected bankfull should lie the first Woloszyn terrace value is considered, the average value of Schumm, Brown and Warner number, the first index of Riley value, the central value of Pickup and Warner method, the Williams number and the middle bench value of the Woodyer biotic method (the second bench value of Woodyer). Finally we considered bench 2 for proposed in the following paper IBA method with its central value out of other discharges where one could expect to find bankfull. So, calculated are the central values of discharge out of all ranges of bankfull discharges mentioned above which were referred to different abiotic and biotic methods and next is calculated an arithmetical average for them which is Q = 18.42 m3 s-1. That value is termed the bankfull value to which one could refer as to one number Qb = 18.42 m3 s-1. This number is a bigger then Q50 = 11.30 m3 s-1 (the two years flood) but still close to Q25 = 21.2 m3 s-1 what follows the general statements of bankfull definition given by many authors and nearly. Also the obtained Qb = 18.42 m3 s-1 is very close to Q = 18.67 m3 s-1 which is the Schumm, Brown and Warner bankfull value for n = 0.025 which also seems to be the best described roughness coefficient of the considered Ochotnica stream cross-section (from our field observations). Finally the obtained Qb = 18.42 m3 s-1 confirms the present hydrological situation in that part of the Polish Carpathians where big floods were experiences in 1997, 2000 and 2003 and when were experienced such values of discharges in the Ochotnica stream which were marked in the field as nearly or just above bankfull but still conforming to the channel shape. The discharge Q20 = 40.00 m3 s-1 was noted at Tylmanowa gauge station for the area of the catchment A = 108 km2 as a flood noted on the Ochotnica stream which is an equivalent of Q20 = 23.95 m3 s-1 for the research cross section described in the present paper and recalculated using the Fall method [34] which is within the range of the value of the bankfull calculated in this study using all the methods employed in the present study. To recapitulate: that value of bankfull Qb = 18.42 m3 s-1 we calculated within the research cross section employing biotic and abiotic methods and we discussed along with other discharges characteristic for that site, we would recommend to any planners, managers and developers but first of all to river engineers who would like to undertake any training works within the considered cross-section of the Ochotnica. This value turned out to be a consensus number when we employed abiotic and biotic methods to calculate bankfull. It looks reliable from the point of view of hydrology and geomorphology but also it covers the biological requirements.

Below we would like to discuss a bit deeper why in our opinion the water level has the influence on invertebrates living within river corridor cross section and at the same time invertebrates might be considered as indicators when talking about bankfull.

Principal Component Analysis described 70% of variance for the first two axes of species data. Ordination axes (Fig.7) clearly indicate changes in community composition and relative abundance of species belonging to three t-years flood levels called here for simplicity of the discussion here benches similarly as in the Woodyer’s study [57] but in the respect of possibility of installing the invertebrate pitfall traps within the measuring (research) area.

Fig. 7. Biplot based on principal component analysis of ground beetles assemblages (1-12) from the Ochotnica Stream sites


Fig. 8. Classification tree of ground beetles assemblages according to TWINSPAN analysis with respect to the characteristic habitats. Photograph coresponds to specific Woodyer benches, 1,2 and 3 respectively

A Two-way Indicator Analysis method implemented by TWINSPAN [22] was used to obtain the ground beetles assemblage groupings in the survey data . Twinspan analysis divided ground beetles assemblages into four groups, in relation to flood disturbance frequency (Fig. 8). annually (–) and periodically (+). Bembidion cruciatum is characteristic for the first bench (localities 4-9).

The right-hand group of assemblages belong to the first bench – so called Bench 1 – associated with Q discharge value between Q = 4.10 ÷ 11.10 m3 s-1 which is nearly the low bench discharge value in the Woodyer’s method (Table 2), the most frequently flooded, even isolated by main stream, meanwhile left bottom group is composed from assemblages belonging to the second bench. Surprisingly, the top left group of assemblages, in spite of completely different environmental conditions (between meadow and spruce forest) still have similar species and community structure. The primary results of Canonical Correspondence analysis are presented in Fig. 9.

Fig. 9. Ordination diagram based on canonical correspondence analysis of ground beetle assemblages with respect to environmental variables (height_V distance from the deepest point in the stream, plant_height – average height of plants in given site, frequency – frequency of floods at each site and bench_1-3 location on particular bench as a dummy variables). Full names of species with preference to particular bench are placed in appendix

A Monte Carlo permutation test indicated significance of the first canonical axis (F-= 2.4, p=0.02), as well as four axes (F =1.51, p=0.05). Cumulative percentage variation of environmental-species data is about eighty percent for the first two axes. Variation in fluctuation of water level seems to be the main factor responsible for changes in species composition. Along Bench 1 concentrate small (4.5-7 mm) species, mostly belonging to genus Bembidion. Second bench so called Bench 2 , associated with discharge range from Q = 11.10 m3 s-1 to Q = 38.40 m3 s-1 (ordinate mostly distribution of medium sized species, characteristic for disturbed habitats (e.g. Pterostichus melanarius), meanwhile third bench described well distribution of mostly bigger forest species (eg. Carabus auronitens, Molops piceus). Species correlated with particular benches was included in appendix 1. Redundancy analysis (Fig. 10) showed relationships between ground beetles structure parameters and environmental variables.

Fig. 10. Biplot based on redundancy analysis of ground beetle assemblage parameters (H – Shannon-Wiener index of diversity, S – Simpson index of diversity, d – Berger-Parker dominance index, e – evenness, abund – total abundance of each assemblage, richness – number of species on each site, dom_biom – total biomass of dominant species, biomass – total biomass of whole assemblage) with respect to environmental variables (description see Fig. 4)

The cumulative percent of variance of both sets of parameters described 99 percent of the variance for the first two axes. Monte Carlo permutation test indicated significance of first and all canonical axes (F= 17.25, p<0.001, F4.96, p<0.02, respectively). The best predictor of channel geometry among community structure parameters was total biomass and biomass of dominant species (Fig. 9). There is strong correlation between habitat fluctuation and Carabid beetle total biomass. It indicates that such factor can be used as a good indicator of different flood levels.

Biomass and size co-varies with many ecological physiological factors and life history of animals. Size is usually assumed to be an adaptive response to history of natural selection. Variation is size represent environmentally induced changes in given habitat. In given communities species replacement with frequency of disturbance occurred. Resource levels and their changes over time are discharge-level dependent. Platt and Connell [33] suggested different models of species responses to natural disturbance. In such model two groups of species are always distinct: early and late species. The first group occurs always just after disturbance and the second one become more abundant later. Life history characteristics, which are important immediately after disturbance, are wide dispersal, rapid establishment and growth to a small size at maturity. Such a description is characteristic also for species from the first bench (Bench 1). Bonn [4] observed increasing flight activity of ground beetles after a flood. In this case, where frequency of disturbance is higher than once a year, only small species with high dispersal power [51] such as species from genus Bembidion can be favorable. In many studies changes in body size between even particular populations depends on disturbance in landscape complexity or after application of polluted food. If the frequency will be lower, such as in case on second bench, the early species will be replaced by later species, much larger and more competitive [26,49].

Directional replacement can then be applied in our studies to explain formation of completely different communities on each bench and /or discharge level. Disturbances such as seasonal flooding eliminate very quickly all species appearing only on the first bench. After then, species start to recolonize the site. Smaller species are able to grow more rapidly and in most cases have smaller life spans. Near the bank species are also adapted to use food resources directly from the stream [6]. Such adaptations can favor less competitive smaller species. A similar situation was observed in relation to plant species [17]. She described phenotypic plasticity of early colonizing species and adaptation to less favorable conditions. It seems that differences in total biomasses between invertebrate communities are good predictors of disturbances such as flood.

On the other hand we cannot test whether food preferences of riverine species are consequences of adaptation and strict specialization to such a food resources [28,29,30,41] or is a consequence of trade off between possible resource utilization (potential niche space) and resource utilization coming from competition (realized niche space). Many authors [2,3,19] pointed out that Bembidion species have a few adaptations for surviving inundation. However it does not exclude a trade-off between competitions between floods.

In natural communities, a seemingly universal feature of large taxonomic groups is a frequency distribution of body sizes among species [7]. Arthropods from grasslands [45], birds or bacteria [12] are highly right skewed in unimodal pattern. The conversion of energy to reproduction is responsible for unimodal distribution, favoring species of medium size [13]. The trade off between the relative advantages of small and large size is responsible for such pattern. Relationships between size and metabolic rate and turnover time, as well as ontogenetic development time and life span were discovered. In the model presented by Brown et al. [7] important is the rate which and individual can acquire resources from its environment and the rate at which it can it convert into reproductive work. In disturbed habitat where the time of acquisition of energy should be as short as possible smaller forms are more successive. That is probably why such ground beetle assemblages have right skewed distributions of body sizes. On the second bench (bench 2) and the third (bench 3) is not so important and the pattern is always unimodal.

Previous applications of ground beetles as bioindicators are known from the literature and have been presented by [11,15,48]. Raino and Niemela [37] briefly identify such group as a good environmental predictor. Also the carabid fauna of riverbanks is very characteristic and typical to such habitat [3,15]. Rickfelder [39] examined applicability of three species of genus Bembidion as indicators in banks of the Elbe River. In his study, the riparian species showed sensitive response to the environmental gradient. Our results showed that frequent water level fluctuations are able to create a new assemblage of species with a characteristic structure. Body size distribution towards very small species seems to be very good predictor for such phenomena as bankfull discharge. Presented in table 2 IBA biotic index should be tested in other water systems (we did it just in mountainous gravel bed stream), however its biological explanation seems to be universal.

To recapitulate the following observations and thoughts, we would like to stress once more that the described IBA method could be used mostly by geomorphologists and river engineers, who are not experienced with invertebrate ecology when they want to compare the traditional obtained results with the survey bankfull methods (abiotic) with so called ecological like approach, which the IBA method seems to be. Especially in very sessile riverine environment where there is a need of any application of river training or river management techniques one would definitely to know the biological changes which could be done by employing such a method. In that sense the IBA approach is a very good indicator.

On the other hand, simple methods of collections (pitfall trap system), measurement and finally classification to different body size class of collected material can be applied by everybody and can be used in different systems. Another advantage is the minimal cost of the analytical tool of the presented method. There is also no need to recognize particular species, just recognize and separate different morphospecies and measure their size. In that context we hope that expansion of such method to many other river systems will improve understanding of three big groups of environmental specialists: engineers, geomorphologists and biologists, which is a key important factors in modern pro-ecological and pro-biological approach to bankfull assessment.


  1. Proposed and described along the paper Invertebrate Assessment Bankfull method (IBA method) could be adopted to find out the bankfull discharge value in gravel bed rivers. It can be used by anybody, even not experienced in the field of ecology or biology. This method is very straight forward when applying it in practice since it requires just an easy way of collection of the material (beetles) and there is no even a need to know species but just only one need to measure their sizes and then to calculate a simple IBA index.

  2. For the Ochotnica Stream the biomass of dominant species is growing according to equation y = 147.15 e 1,5239x, (t = 4 .72, p = 0.0008), where x is a number of the bench.

  3. The results of bankfull range obtained with IBA method confirm values of bankfull found out using abiotic methods (e.g. the Riley, the Woloszyn, the Wolman, the Williams etc.). Also the Woodyer method based on plants as biotic indicators confirms the numbers of bankfull range obtained with the method proposed in the following paper. Finally the bankfull value which could be recommended for river engineers, planners, hydrologists, biologists and fluvial geomorphologists for the practical and ecological reasons within the research Ochotnica stream cross-section is 18.42 m3sec -1

  4. Both a shape and size of insect bodies is highly connected with frequency of natural disturbances caused by occurrence of variety of discharges in a particular stream cross section. In that context if any of discharges can be considered as bankfull discharge dimensions of the beetles are strictly associated with that bankfull value.

  5. The distribution of biomass in carabid beetles assemblages is correlated with places of occurrence of specific assemblages, therefore it depends on bankfull level or/and river bench also associated with a bankfull stage.

  6. High flood frequency is a main factor causing changes in distribution of body size of beetles in relation to theoretical models and becomes more right skewed.

  7. There are specific species, which are having strict preferences to a certain scope of frequency of floods, which means they are prone to some specific discharge values. Another words, they are present only on some bench levels, which are associated with specific t-years floods. Among those discharge values one could expect a discharge value.

  8. The new method, proposed in present paper, could be used as a verify tool for the abiotic methods of used already for calculating the bankfull, and which are taking into consideration pure morphology of the river channel. In the present time it seems that consideration of living organisms within a river channel influence presented by so-called biotic indexes (in that case the IBA index) is equally important as indexes associated with a geometry of a river cross section and river channel morphology.

  9. The IBA method seems to be useful for multi-braided gravel stream channels, as some of the abiotic methods do not work an appropriate way in such environment.

  10. The future work with IBA method should be directed into lowland rivers with fine gravel and sand beds.


We would like to thanks to the MSc students involved in the field and laboratory work: Pawel Koterba and Renata Kedzior. Also great thanks to Prof. Paul Carling from the University of Southampton in the UK for his kind comments. The research was supported with the grants: BW/IZ/7/2005, BW/IZ/5a/2007 and BW/KIW/2005-06.


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1. Species characteristic for a particular bench (IBA method) according to CCA analysis:

Bench 1
Nebria picicornis (Fabricius, 1801).
Nebria fuscipes Fuss, 1849.
Cicindela hybrida Linné, 1758.
Omophron limbatum (Fabricius, 1777).
Elaphrus aureus P. W. J. Müller, 1821.
Bembidion pygmaeum (Fabricius, 1792).
Bembidion properans (Stephens, 1828).
Bembidion varium (Olivier, 1795).
Bembidion varicolor (Fabricius, 1803).
Bembidion fasciolatum (Duftschmid, 1812).
Bembidion ascendens (K. Daniel, 1902).
Bembidion stephensi stephensi Crotch, 1866.
Bembidion cruciatum polonicum J. Müller, 1930.
Anisodactylus binotatus (Fabricius, 1787).
Harpalus rufipes (De Geer, 1774).
Harpalus affinis (Schrank, 1781).
Harpalus smaragdinus (Duftschmid, 1812).
Harpalus solitaris Dejean, 1829.
Poecilus lepidus lepidus (Leske, 1785).
Poecilus versicolor (Sturm, 1824).
Pterostichus nigrita (Paykull, 1790).
Agonum sexpunctatum (Linné, 1758).
Agonum muelleri (Herbst, 1784).
Amara ovata (Fabricius, 1792).
Amara montivaga Sturm, 1825.
Amara fulva (O. F. Müller, 1776).
Amara equestris equestris ( Duftschmid , 1812).
Chlaenius nitidulus (Schrank, 1781).
Chlaenius tibialis Dejean, 1826.

Bench 2:
Carabus nemoralis O. F. Müller , 1764.
Clivina collaris (Herbst, 1784).
Asaphidion flavipes (Linné, 1761).
Pterostichus strenuus (Panzer, 1796).
Agonum gracilipes (Duftschmid, 1812).
Amara similata (Gyllenhal , 1810).
Amara aenea ( De Geer, 1774).
Amara familiaris (Duftschmid , 1812).
Badister bullatus (Schrank, 1798).
Badister dorsiger (Duftschmid, 1812).

Bench 3:
Leistus ferrugineus (Linné, 1758).
Nebria brevicollis (Fabricius, 1792).
Carabus glabratus glabratus Paykull, 1790.
Carabus auronitens Fabricius, 1792.
Cychrus caraboides (Linné, 1758).
Trichotichnus laevicollis (Duftschmid, 1812).
Pterostichus aethiops Panzer, 1796.
Pterostichus burmeisteri Heer, 1838.
Abax ovalis (Duftschmid, 1812).
Molops piceus (Panzer, 1793).
Amara aulica (Panzer, 1796).

2. Plants characteristic for a particular bench (Woodyer method):

Low bench
Urtica dioica L.
Tanacetum vulgare, L.
Carex fusca,
Bellardi & All.
Carex acutiformis, Ehrh.
Carex rostrata, Stokes
Dactylis glomerata, L.
Anemone nemorosa, L.

Middle bench
Primula elatior, (L.) Hill
Deschampsia caespitosa, (L.) P. Beauv.
Plantago lanceolata, L.
Urtica dioica
Leontodon hispidus, L.
Tussilago farfara, L.
Ranunculus acris, L.
Alchemilla sp.
Petasites albus, (L.) Gaertn.

High bench
Salix purpurea, L.
Salix alba, L.
Picea abies, (L.) H. Karst.
Fagus sylvatica, L.
Valeriana officinalis, L.
Galium odoratum, (L.) Scop.


Accepted for print: 10.02.2008

Artur Radecki-Pawlik
Water Engineering Department,
Environmental Engineering and Geodesy Faculty,
Agricultural University of Cracow, Poland
Al. Mickiewicza 24-28, 30-059 Cracow, Poland
Phone: (48-12) 633-11-70
email: rmradeck@cyf-kr.edu.pl

Tomasz Skalski
Department of Entomology,
Institute of Zoology, Jagiellonian University, Cracow, Poland
Ingardena 6, 30-060 Cracow, Poland
Phone :(48-12) 634-37-15
email: tomasz_skalski@yahoo.co.uk

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