REGIONAL DIFFERENTIATIONS OF THE SUSPENDED SEDIMENT TRANSPORT IN THURINGIA AND THEIR RELATION TO SOIL EROSION

L. BAUER and W. TILLE Germany D.D.R.

ABSTRACT During the hydrologie years 1961 and 1962,13 sampling stations within thewatershed of the river Unstrut carried out systematic measurements of the suspended sediment charge. Statistical analysis of the data showed partially significant differences between the mean values of different cross sections (a = 5%) within the area which covers only about 5,000 km2. The functions for estimating suspended sediment discharge, which state the average increase of the suspended sediment discharge in g/s with the water discharge in m3/s, were calculated for 11 cross sections after the simplified method of Remy-Berzen- covich (1960). The parameters 1g b and m of this empirical function of the form

Ig Qs = Igb + mlgQ were studied more closely. The parameter Ig b shows a close negative correlation with the long time mean water discharge (r, = —0.836). This is a hint al its strong dependence on the hydrologie conditions of the catchment basins of the sampling stations. The river basins with a high part of triassic limestone (Muschelkalk) and a little catchment basin at the edge of the hercynian mountains with predominantly paleozoical rocks have the highest values for m. The average value of the parameter m for these cross sections is 2,63 as against 1.78 for the remaining cross sections. After the U—test of MANN and WHITNEY the difference is significant (a = 5%). The different values of the parameter m can be explained by the specific mechanism of erosion of the different soils of Thuringia which was studied closely by Werner (1966). In the evaluation of the erodibility of these soils there exists vast agreement between the results of the plot tests made by Werner (1966) and the results of the measurement of suspended sediment described here. Hitherto existing knowledge allows to develop from the functions for estimating suspended sediment discharge, so-called functions for the estimating of washout of the form lg.4 = ]gfr+(»i—1) Ig F^—m(3—Igg). They determine the mean value of washout A in g/s.kms for every value of the runoff per square kilometer q in 1/s.km3. More detailed investigations in the catchment basin of the river Roda (243 km2), about which will be reported later, serve for the further elucidation of the connection between soil erosion and suspended sediment transport.

RÉSUMÉ La différenciation régionale du transport des matières solides en suspension par rapport à l'érosion du sol en Thurlnge Pendant les années hydrologiques 1961 et 1962 des mesurages systématiques des teneurs en suspension furent exécutés à l'aide de 13 stations de prélèvement d'échan­ tillons du bassin versant de la rivière d'Unstrut. L'analyse statistique des observations fournissait en partie des différences notables chez les valeurs moyennes des sections différentes (a = 5%) au dedans du territoire, ayant seulement à peu près 5.000 km2. Avec la méthode simplifiée de Remy-Berzencovich (1960) les« fonctions de matières en suspension » pour 11 stations de la section transversale furent calculées, indiquant l'augmentation moyenne des débits solides en suspension en g/s avec !e débit d'eau en m3/s. Les paramètres 1g b et m de cette fonction empirique de formule lgCs = Igb+mlgQ furent étudiés de plus près. Le paramètre lg b fait voir une étroite corrélation négative avec l'annuel débit moyen (rs = —0,836). C'est une indiquation de la forte dépendance

367 de la situation hydro logique des bassins versants des stations de prélèvement d'échan­ tillons. Le paramètre m montre une certaine dépendance de la situation pétrographique et pédologique des bassins versants des stations. Les plus grandes valeurs pour m ont donc les bassins versants avec une grandepart de pierre calcaire triassique (Muschelkalk) et un petit bassin versant au bord des montagnes hercyniennes, où des roches palëozoiques sont prédominants. La valeur moyenne du paramètre m pour ces stations est de 2,63 en face de 1,78 pour les autres stations. La différence est suivant le « f-test» de Mann et Whitney significant (et — 5%). Les valeurs différentes du paramètre m peuvent être expliquées parle mécanisme spécifique d'érosion des sols différents en Thuringe qui a été exacte­ ment exploré par Werner (1966). Au point de vue de l'érodibilité de ces terrains existe aussi un accord profond des résultats des observations par Werner 11966) et les résultats des mesurages des matières solides en suspension présentés ici. Les résultats obtenus jusqu'à présent permettent de trouver en partant de l'estima­ tion des matières solides en suspension, les fonctions pour l'estimation delà denudation par la formule

\gA = lgA + (m-l)lgFN-m(3-l6?) Elle détermine la valeur moyenne de la denudation A en g/s km3 pour chaque valeur de l'écoulement par km2 en 1/s km2. L'étude entre l'érosion du sol et le transport des matières solides en suspension fut poursuivi avec des investigations en détail au bassin versant de la rivière de Roda {243 km2) sur lesquelles un rapport également est donné.

1. INTRODUCTION

Studies of the suspended sediment transport of running waters have been carried out in the German Democratic Republic only to a little extent in comparison with various other countries. The important tasks of water management, however, which have to be solved now and in near future, call for more intensive scientific investigations into this hydrologie phenomenon. The systematic establishment of an official obser­ vation network for suspended sediment discharge measurements has been taken into the Programme of the German Democratic Republic for the International Hydro- logical Decade 1965-75. Recently results of possible importance for our future work have been gained by studies on the suspended sediment transport of some water courses in Thuringia which were carried out independently of the IHD. These studies were limited in time. Measurements of the silt charge have been carried out in Thuringia since I960. Their aim is, in addition to the usual quantitative recording of the suspended sediment transport of the water courses that have not yet been recorded in that respect, to clear up the factors which decisively influence the suspended sediment transport of the rivers in this area. The answer to this questions makes necessary positions of the observation stations which offer the same possibilities for comparison of water courses whose drainage areas show different characteristic features. The geological constitution and in close connection with that the soil conditions are such an important feature in Thuringia. The central part of Thuringia, the Thuringian basin, is geologically clearly divided in consequence of the alveolate occurrence of the 3 epochs of the German Trias (Buntsandstein, Muschelkalk, Keuperl and is bounded in the North and in the South by the paleozoic rocks of the Hercynian and Thuringian mountains. Generally, the soil conditions follow the distribution of the rocks, but they are in detail far more complicated, because often covers of pleistocenic hillside wastes, which are located above the bed rock (Schilling and Wiefel, 1962, Siegel, 1963, Werner, 1964a) and loess covers, especially in the central area, are of importance as being the original substratum for pedogenesis, and not the bed rock itself. The relations between the pleistocenic hillside wastes and the bed rock are close enough, however, to reflect the geological macrostructure in the kinds of soil. Generally sandy to loamy soils correspond

368 to the lower Trias (B un tsand stein), limy-clayey soils to the upper Trias (Keiiper), The loess deposits reach their largest extent in the Keuper area. Therefore, silly soils are very extensive in this area. Under these circumstances the geological macrostructure of the Thuringian basin had to be taken into consideration when ihe observation network for suspended sediment measurements was established, in order to study the possible influence of the rocks and soils.

2. CHARACTERIZATION OF THE SUSPENDED SEDIMENT TRANSPORT IN THE THURINGIAN BASIN

The main part of the Thuringian basin is drained by the river Unstrut (6,388 km2). 13 sampling stations were established within this area and one out of it. Altogether they control 5,319 km2. The area of the catchment basins of the stations and their distribution over the most important rock series is shown in table 1.

TABLE 1 Area and distribution of the catchment basins of the stations over the most important rock series

Area of the Predominant rocks Watercourse Samplingstation catchment basin (km3)

Paleozoical rocks (schists, Krebsbach I berg 14 conglomerates, porphy- rites) Lower triassic sandstones Roda Zollnitz 254 (Bun tsand stein) Wîpper KannawuiT 639 Helme Bennungen 897 Middle triassic limestones Linderbach Linderbach 42 and argillaceous rocks Helbe Bliederstedt 260 Unstrut Merxleben 650 Unstrut Nâgelstedt 725

Upper triassic plasterstones Gramme Wer ningshausen 291 and clays incl. larger Lossa Leubingen 392 loess deposits Very different rocks Apfelstâdt Ingersleben I 369 (paleozoic and Trias) Gera Ingersleben II 443 Gera Ingersleben III 812 Unstrut Oldisleben 4,168

When the sampling stations were established the existing gauge network and water management needs (storage reservoir) were also of importance. Therefore, in addition to the most important rocks mentioned above others also occur in ibe drainage basin,

369 though to a lesser degree. Only the catchment basin of the station Roda/Zôllnitz has an ideal structure (only Buntsandstein). The measurements of the silt charge were carried out according to the filter method following the procedure of the Bayerische Landesstelle fur Gewàsserkunde, MOnchen (1952|. The sampling was carried out in all observation stations nearly at the same time, mostly during the two hydrologie years 1961 and 1962. In Thuringia these two years differ clearly from each other in their hydrologie character. The hydrologie year 1961 is to be defined as strongly abnormal according to the discharge hydrograph and to the volume of runoff, both of which were extremely high. The hydrologie year 1962 showed medium proportions. During the two years the most important minima and maxima of the discharge hydrograph were noticed at all stations at the same time, so that the area as a whole showed uniform hydrologie characteristics in this respect. The following features are particularly suitable for the characterization of the suspended sediment transport and the comparison of the watercourses studied: 1. Mean annual silt charge; 2. Annual suspended sediment discharge in tons per square kilometer; 3. Silt charge fluctuations; 4. Parameter of the Schwebstoff- and Abtragsfunctions.

2.1. The mean silt charge in water courses of the Thiiringian basin. Table 2 shows the mean annual silt charges as they were calculated from the single measurements of the two hydrologie years 1961 and 1962 for each station. The margins of error which were found statistically are noted, too.

TABLE 2 Mean silt charges

Water course Sampling station Mean annual silt charge in g/m3

1961 1962 Krebsbach Iberg 106 ± 45 444 ± 175 Roda Zollnitz 268 ± 141 Wipper Kannawurf 233 ± 86 232 ± 105 Helme Bennungen 138 ± 50 107 ± 15

Linderbach Linderbach 93 ± 49 28 ± 5 Helbe Bliederstedt 202 ± 148 84 ± 68 Un strut Merxleben 138 ± 35 71 ± 34 Un st rut Nâgelstedt 189 ± 43 97 ± 43

Gramme Werningshausen 80 ± 8 77 ± 19 Lossa Leubingen 267 ± 96 114 ± 12

Apfelstàdt Ingerslben I 220 ± 95 50 ± 26 Géra Ingersleben II 167 ± 89 49 ± 22 Géra Ingersleben 111 167 ± 99 48 ± 29 Unstrut Oldisleben 223 ± 43 122 ± 45

370 The values in table 2 show considerable differences not only between tJie various stations but also between the two water years. These differences can possibly have come about at random, because the measurement have the character of tests made at random, strictly speaking. Statistical analysis, however, showed that the differences between certain stations are significant. The extremely low values of the watercourses Gramme and Linderbach (east part of the Unstrut area) and the values of the water courses Wipper, Helme, Krebsbach, and Lossa are particularly secured by statistics (a =5%). The differences between the two hydrologie years, however, —although generally rather high,— are mainly in the range of chance. This results hint at the fact that the mean annual silt charge of the water courses of the Unstrut area depends on factors whose influence is not blurred by the hydrologie conditions which change from year to year.

2.2. Annual suspended sediment discharge in ions per square kilometer in the Thuringian basin

Because of the various extents of the water courses and the drainage areas the most suitable index for comparison of their transport capacity is the sediment discharge in tons per square kilometer per year (table 3).

TABLE 3 Annual suspended sediment discharge in Ions per square kilometer

Water course Sampling station Suspended sediment discharge in tons per square kilometer

1961 1962

Krebsbach I berg 74 ± 45 272 ± 174

Roda Zollnitz 55 ±28 Wipper Kannawurf 44 ± 16 33 ± 15 Helme Bennungen 64 ± 23 28 ± 5

Linderbach Linderbach 13 ± 8 2± 0,4 Helbe Bliederstedt 51 ± 38 12 ± 10 Unstrut Merxleben 47 ± 12 15± 7 Unstrut Nàgelstedt 64 ± 15 21 ± 9

Gramme Werningshausen 12± I 5 ± 1 Lossa Leubingen 41 ± 15 5± 0,9

Apfelstiidt Ingersleben I 94 ± 39 11 ± 6 Gera Ingersleben u 76 ±40 10 ± 5 Gera Ingersleben III 72 ±43 !0± 6 Unstrut Oldisleben 65 ± 13 22 ± 8

371 During the abnormal water year J 961 the mean suspended sediment discharge per square kilometer in the catchment areas of the water courses Linderbach and Gramme was distinctly lower than at the other sampling stations where these values generally are in one order of magnitude. Compared to it, 1962 shows a stronger differentiation. Apart from the Krebsbach, in the very small catchment area of which (14 km5) some thunderstorm precipitations could show extreme results, the highest values were found in Btintsandstein areas (Wipper, Helme) in the course of this nearly normal hydrologie year. The lowest values can be found for the water courses Linderbach and Gramme and for the Lossa. The two water courses mentioned at last drain the loess covered Keuper area. The Muschelkalk areas generally occupy a mean position.

2.3. The sill charge fluctuations

In accordance with the temporal distribution of the hydrologie events the rhythm of the silt charge was similar during the two hydrologie years 1961 and 1962 in all stations, the highest values of sill charge always happening in connection with the maxima of the discharge. Nevertheless, certain water courses differ clearly in the heights of their extreme values and the frequency of certain loads. In particular the following tendency can be noted: in the case of the water courses of the Muschelkalk- areas the suspended sediment discharge can suddenly reach extremely high values. For example a load of 10012 g/m3 was noticed in the Helbe in 1961 within a short time. During the greatest part of the year, however, the silt charge is low (90% of all values are under 100 g/m3). Therefore, the frequency distributions of these obser­ vation rows are rather assymmetric even in the case of logarithmic classification the frequency maximum being between 10 and 60 g/m3. A very quick oscillation of the silt charge can be noted in the watercourses of the Buntsand stein-areas. Generally the highest values are here lower than in the rivers of the Kalk-areas. The frequency distributions of the observation values are nearly symmetric in the case of logarithmic classification. The frequency maximum of these distributions is between 40 and 100 g/m3. The rivers Gramme and Lossa which drain the loess-covered plasterstones and clays of the Keuper in the eastern part of the Unstrut-area show very small amplitudes of the silt charge. Both high and low values are seldom, a silt charge over 500 g/m3 was never noticed in the Gramme during the two years. Therefore the logarithmic frequency distributions of the observation rows are very narrow with a distinct maximum which is in the case of the Gramme between 40 and 100 g/m3 and in the case of the Los;a between 80 and 200 g/m3. All these distributions were checked by means of the %z — test. There are always significant differences between them.

2.4. The parameters of the Schwebstoff- and Ablrags-j'unciions

Remy-Berzencovich (I960) has developed a method which allows to represent the average increase of the suspended sediment discharge with the water discharge in an empiric function of the form Ig Qs = Ig h-\-m Ig Q. Both the parameters Ig b and m of this function were calculated for 11 Thuringian water courses (table 4). The parameter Ig b shows the suspended sediment discharge Qs in g/s which is to be expected in the case of the water discharge Q = 1 m3/s on an average. As this is a general relation the parameter lgè must decrease when the mean annual discharge MQ increases.

372 TABLE 4 The parameters of I he Schttsebstoff— functions and the Ablrags — functions

Water course Sampling station ]g b m 1g d

Krebsbach I berg 3.45 620 2.57 420 -2.78 741

Roda Zollnitz 1.98 136 2.10 882 -1.67 858 Helme Ben mm gen 1.17 583 1.80 460 -1.86 216

Helbe Bliederstedt 1.48 525 2.39 082 -2.32 842 Unstrut Merxleben 0.83 273 2.64 473 -2.47 498 Unstrut Nagelstedl 0.79 282 2.90 656 -2.47 345

Gramme Werningshausen 1-89 958 1.32 667 -1.27 555 Lossa Leu bin gen 2.06 6S6 1.11 447 -0.97 970

Apfelstadt IngersJeben I 1.02 109 2.07 507 -2.44 438 Gera Ingersleben III f.03 819 2.00 000 -1.95 225 Unstrut Oldisleben 0.57 997 2.01 037 -1.79 267

There is a very close correlation between the long time mean annual water discharge MQ and the parameter Ig b as is expressed in the high rank correlation coefficient according ^o Spearman {ys — —0.836). This coefficient is statistically safe (a = 0.1%). The correlation can be expressed for the Unstrut area by the regression equation }gb = 1.88-1.26 igMQ which may serve for the approximate evaluation of the parameter for any cross sections within this area. Obviously it is determined to a far extent by the hydrologie conditions of the drainage basins. There is an analogous correlation for the parameter m which cannot be determined quantitatively. According to table 4 the water courses Helbe, upper Unstrut (Merxleben, Nagel­ stedt) and Krebsbach have the highest values. The rivers Gramme and Lossa have the lowest values. The first group comprises the water courses from the MuschelkaIk-areas and the only example from the palaeozoic period. The second group contains the water courses of the Loess-covered Keuper hills. Therefore, it is obvious to bring the value of the parameter m into connection with the rocks of the catchment areas. The average value for m is rd 2.63 for the water course of the first group, for ail the other water courses it is rd 1.78. According to the U — test after Mann and Whitney the difference is significant (a = 5%). From this can be deduced that the geological and soif conditions reflect themselves in m. Remy-Berzencovich (1960) found this value to be 2.755 and 2.723 in the case of the alpine rivers Enns and Gail. He explained the small difference by the similarity of the catchment basins, both of which consist of limestone and main bottom. The coincidence with the corresponding values from Thuringia in this connection is interesting and makes probable the validity of the connections mentioned above for a larger area.

373 3. THE RELATIONS TO SOIL EROSION

The extensive studies of Schultze (1959) showed the wide distribution of soil erosion also for Thuringia. But Schultze (1959) with his methods did not succeed in evaluating the erodibility of the most important soils correctly. Recently detailed investigations into the soil erosion in Thuringian have been carried out by Werner (1962, 1964a, 1964b, 1965, 1966) which have, among other things, supplied important knowledge on the mechanism of destruction and the erodibility of soils of the most important Thuringian soils. According to Werner (1964b) the clearly to be noticed differences in the erodibility are predominantly determined by the characteristic group granulation/fabric. The loamy sand soils which spread widely in the Buntsandstein areas show the highest degree of erodibility. The skeleton-rich clay soil in muschelkalk proved to be the most resistant. Concerning the mechanism of destruction these soils differ from one another in a characteristic way. The different aggregate stability of the soils is the reason of this, first of all. They are easily destroyed on the loamy sand soils. In the case of low runoffs only a water flush of fine soil separates occurs, in the case of high runoffs the material is mostly transported unsortedly. The aggregates of the clayey soils showed a high stability. The intensity of low runoffs is generally not sufficient to transport this relatively coarse material. Only in the case of a very strong intensity of the runoffs suddenly a high soil loss may occur when the running water is able to transport the soil aggregates undestroyed. Werner (1966) was able to prove the new knowledge of soil erosion in Thuringia, which are mentioned here, by careful plot tests, exact analyses of soil profiles and by mapping studies. On the basis of these results the regional differentiation of suspended sediment transport in Thuringian water courses, described here, may be explained. Firstly there exists a good coincidence of the studies carried out by Werner (1964a) and the results of our measurements of suspended sediment concerning the relatively big destruction in the Buntsandstein areas (table 3). The different mechanism of destruction of soils in Buntsandstein and in Muschelkalk has a parallel in the fluctu­ ations of the silt charge, the frequency distributions of the loads and the different parameters m of the 3chwebstoff-functions of the water courses. The silt charge can quickly oscillate in Buntsandstein areas, because the destruction processes react to the precipitation and runoff intensity very subtly. When the intensity of destruction of the soils increases the material becomes coarser. Therefore, the mass as a whole cannot be transported any longer in a suspended state. Therefore, the silt charge of the water courses has certain limitations which depend on the contents of the soil of sizes of grain which can be suspended,

The soils in the Muschelkalk areas are stable most of the time of the year and the watercourses, therefore, show only little transport of matter. But during heavy rainfalls and in thecase of thaw accompanied by a big amount of runoff the stable soil aggregates can be led into the waters to a large extent and they can be dissolved during transport into their clayey soil separates. The material can excellently be suspended and the silt charge easily reaches extreme values. This sudden rise of the suspended sediment discharge involves the high value of the parameter in the Schwebstoff-function. The well-balanced silt-charge transport of the water courses of the loesscovered Keuper hills must be explained by the favourable hydrologie properties ofthe loesses and the chernozem-like soils which developed on them taking into consideration the favourable transport properties of the predominantly silty material. The relations between the regional differentiation of the suspended sediment transport of the soil erosion in Thuringia allow the transformation ofthe Schwebstoff- function Ig Qs = Ig b+m !g Q in such a way that it expresses the average increase

374 of the dénudai ion A in g/s.km3 wiih the increase of the discharge in second liter per square kilometer: IgQ = lg/V~3-h1g<7

Ig A <= Ig b + (m— I) ]g FN - m<3 - Ig q)

Igrf = lgt + (m-l)lgFw-3m \%A — \gd + m lg(/.

The parameters ]g b and m of the SchwebstofT-function are known as well as the size of the catchment basin Fs, terhefore Ig d of the Abtrag-function can easily be calculated (table 4).

4. FURTHER INVESTIGATIONS INTO THE CATCHMENT BASIN OF THE RODA

Because of the importance of the Buntsandstein areas —the intensity of the de­ struction processes and the extent of the sediment runoff— recent studies have been concentrated on the representative river basin of the Roda. The catchment basin of the sampling Gernewitz (245 km2), where since 1963 daily observations of the silt charge have been carried out consists exclusively of layers of Buntsand stein and 52% are covered by woods. Tn addition to the silt charge the water temperature is daily measured and sometimes the ignition loss of the suspended sediments is defined and size analyses are carried out. As these investigations have not yet come to an end only preliminary results can be offered here. At first the fact shouîd be mentioned that the results of earlier measurements have been confirmed in most respects by the new observations which have been carried out for 3 1/2 years. The frequency distri­ bution of the loads is in the case of logarithmic classification nearly symmetrical. Markedly high extreme values of the silt charge have not been found even in the case of floods. The sediment hydrograph of the silt charge shows the typical oscillations. According to present findings the parameters of a newly calculated SchwebstofT- function correspond to those of an older one although the sampling station rd. is. 3 km upstream now. Determinations of ignition losses which have been carried out show that the transport of organic substances which pollute the water is rather constant and low, therefore hardly any influence on the results of the measurements is to be expected. Werner concentrated his studies of the soil erosion on this catchment basin for the same reasons which were decisive for the exact observation of this water course. In future further comparison of the various observations will be possible. A balance of the material cannot yet be eslablished for methological reasons, the suspended sediment transport is influenced by further factors as e.g. processes in the river bed and, especially bank erosion. Therefore, an exact registration of the bank condition and its changes in the course of time is necessary. Studies of this kind have been carried out in Thuringia for years (Niemann, 1962; Bauer, Hiekel, Niemann, 1964) and are continued. In spite of the yet unsolved problems there is no doubt that the destruction of soils by anthropogenic reasons is decisively involved in the supplies of material into the water courses in Thuringia. This is proved by bottom land sediments which have recently been studied. Jager (1962) was able to show that the sedimentation of bottom clay is caused by anthropogenic influences and may go parallel with the chief sections of clearing of land in the single areas. He distinguishes a pre-historic and a historic sedimentation cycle. Schultz (1965) came to similar results on the basis of investigations into the sediments of the Unst rut-everglade. Tn the case of the bottom land of the Roda the existence of two existence of two periods of succession of sedi-

375 ments could be shown (Werner, 1965). A predominantly coarse, very differenciated sediment, which proves to be a medieaval flood plain accumulation lies over rather a homogeneous, fine sandy loam. It may be regarded as coarse grained variant of the bottom clay, whose deviative habit is caused by the area where it originates (Buntsand- stein). This shows clearly that in Thuringta all three parts of recent fluviatile material drifting—erosion, transport and accumulation—are subject to regional differentiation caused by rocks and soils. It is very probable that this fact is valid not only in Thuringia, Therefore, the study of the influence of the rocks and soils on the investigation into the processes of the suspended sediment transport is very important. Therefore, we suggest that when an observation network for suspended sediment measurement is established, which is especially done within the IHD, the establishment of such representative stations is especially taken into consideration which allow all observations of suspended sediment transport.

LITERATURE

BAUER, L. (1953): Entstehung und Verhiitung von Hochwasser am Beispiel des FluB- gebietes von Unstrut und Géra. VEB Verlag Technik Berlin. BAUER, L. (1960): Beitrage zur Hydrogeographie Thûringens. Berichte zur Deutsche» Laiuleskunde, 25,2. Bad Godesberg. BAUER, L. (1961): Zur Hydrogeo graphie des Schwarza- und Rodagebietes — ein Beitrag zur Gewasserkunde und Gewasserpfiege in Thuringen. Archie fitr Natur- schutz und Landschaflsforschiwg, 1, S. 99-141. BAUER, L., W. HIEKEL und E. NIEMANN (1964): Ausbauzustand und Ufergeholz der FlieBgewâsser im Thiiringer Gebïrge (Thùringer Wald und westliches Schiefer- gebirge) — ein Beitrag zur Landschaftspfiege an Gewassern. Wissenschaftliche Zeitschrift der Martin-Luther-UniversitSt Halle-Wittenberg, Sonderheft, S. 171-185. BAUER, L. und W. TILLE (1966): Die Sinkstoffùhrung der FlieBgewâsser des Unstrut- gebietes — ihre hydrogeographische und landeskulturelle Problematic Petermanns Geographische Mitteihmgen, 110, 2, S. 97-110. Bayerische Landesstelle fur Gewasserkunde Miinchen (1952): Anleitung fur die Durch- fiihrung von Schwebstoffmessungen. GEYER, S. und H.-G. HEYM (1958): Problème des Hochwasserschutzes im Unstrut- Helme-Gebiet. Wassenvirtschaft-Wassertechitik, S, 3, S. 99-105. JAGER, K.-D. (1962): iiber Alter und Ursachen der Auslehmablagerungen thuringischer Fliisse. Prahistorische Zeitschrift, 40, H. 1/2. NIEMANN, E, (1962): Die natiiriiche Ufervegetation in ihrer Bedeutung fiir Ufer- bepflanzung und ingenieurbiologische MaGnahmen. Zeitschrift fiir Landeskuititr, 4, S. 187-206. REMY-BERZENCOVICW, E. (1960): Analyse des Feststofftriebes fliefiender Gewasser. Schriftetireihe des Osterreichischen Wasserioirtschaftsuerbandes, H. 41, Wien. RJNSUM, H. van (1950): Die Schwebstoffuhrung der bayrischen Flusse. In: BeitrSge zur Gewasserkunde. Festschrift zum 50-jahrigen Bestehen der Bayerischen Landes­ stelle fur Gewasserkunde Miinchen. SCHILLING, W. und H. WJEFEL (1962); Jungpleistozàne Periglazialbildungen und ihre régionale Differenzierung in einigen Teîlen Thûringens und des Harzes. Géologie, 11, S. 428-460. SCHULTZ, A. (1965): Die geomorphologische Entwlcklung des mittleren Unstrut- gebietes im jungeren Pleistozan und Holozan. Wissenschaftliche Zeitschrift der Friedrich-Schiller-Universitat Jena, Math.-Nat. Reihe, 14, 4, S. 45-53. SCHULTZE, J.H. (1959): Die Bodenerosion in Thuringen. 2. Aufl., Petermanns Geo­ graphische Mitteihmgen, Erganzangsheft, Nr. 247. Gotha. SIECEL, R. (1965): Jungpleistozàne periglaziale Verwitterungs- und AbtragungsvorgSnge im Ostthuringer Buntsandsteingebiet — ihre klimatischen Differenzierungen und Beziehungen zum Ausgangsgestein. Wissenschaftliche Zeitschrift der Friedrich- Schiller-Untœrsltât Jena, Math.-Nat. Reihe, 14, 4, 3. 37-44. TILLE, W. (1965): Ergebnisse von Sinkstoffmessungen an thûringischen Flielîgewâssern. Wissenschaftliche Zeitschrift der Friedrich-Schiller-Universitat Jena, Math.-Nat. Reihe, 14, 4, S. 107-118. WERNER, D. (1962): Der Bodenabtrag als pro flip ragen der und reliefgestal tender Faktor auf AckerbÔden in Thuringen. Geographische Berichte, 7, A, S. 378-395. 376 WERNER, D. (1964a): Frofilbild und Leistungspiitential abtragsgeschadigter Bôden in Sudosithiirmgen. Albrecht-Thaer-Archw, 8, 6/7, S. 509-524. WERNER, D. (1964b): Experimentelle und kartierende Arbeiten zur Erfassung des Wirkungsmechanistnus der Bodenabtragung und ilires Einflusses auf die Siandort- qualitat ackerbaulich genutzter Hanglagen. Arbeiten des Instituts fur Melio- rationswesen und Grunland der Friedrich-Schi lier-Univers it a I Jena, S. 28-32. WERNER, D. (1965): Holozane Auesedimente im Unterlaufgebiel der Roda. Wissen- schaftliche Zeitschrift der Friedrich-Schtller-Unioersitât Jena, Math.-Nat. Reihe, 14, 4, S. 73-78. WERNER, D. (1966): Bodenerosion in Thûringen. TorschungsabscliuBbericht des Instituts fur Mel io rations wesen und Grunland der Friedrich-Schiller-Univers it at Jena.

Addresses of the authors:

Professor Dr. Ludwig BAUER, Direktor des Instituts fur Landesforschung und Natur- schutz Halle/S. der Deutschen Akademie dei* Landwirtschaftswissenschaften zu Berlin, DDR-402 Halle/S.. Neuwerk 4. Dr. Walter TILLE, Institut fur Lan des forschung und Naturschutz Halle/S., Zwetgstelle Jena, DDR-69 Jena, Steiger 17.

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