International Journal of Fieldwork Studies, 2004 2 (1)

SELECTION OF HUMAN INFLUENCED FIXED SAND DUNES ON THE BASIS OF MORPHOMETRIC MEASUREMENTS, SOUTH NYÍRSÉG REGION, HUNGARY

Tímea Kiss kisstimi@earth.geo.u-szeged.hu
György Sipos sipos.gyorgy@stud.u-szeged.hu
Katalin Bódis bodis@earth.geo.u-szeged.hu
Károly Barta barta@earth.geo.u-szeged.hu

University of Szeged, Department of Physical Geography and Geoinformatics, Szeged, 6722 Egyetem u. 2-6., Hungary [http://www.geo.u-szeged.hu]

Abstract

The aim of this paper is to present a geomorphological method for environmental scientists to select those places within a slightly human influenced area which have been under intensive human impact.
The paper applies various methods to describe and classify the sand dunes of the study area using morphological and morphometric characteristics. After defining different dune types and their parameters it was possible to select those dunes that were exposed to significant anthropogenic impact for different periods at various places.
Seven dune types were separated: edge, edge-like, pseudoparabolic, filled parabolic, partially and unfilled parabolic, oval shaped hummocks, sand ridges. Considering the relative height, hackliness and the rythm of dunes half of the eroded dunes (52%) fall within the 1 km vicinity of former and present day settlements. A definite connection was proven between the intensity of human impact on environment and the rate of erosion on fixed sand dunes at different test sites.
For further application the method is recommended in areas where the surface is covered by loose materials and the landforms have been exposed to significant human influence.

Key Words

human impact, erosion, dune morphometry, dune classification, parabolic dune association, Hungary

Résumé

Le but de cet article est de présenter une méthode géomorphologiquue pour des scientifiques spécialistes d’environnement afin de sélectionner ces endroits á l’intérieur d’une aire légérement influencée par l’homme, laquelle a connu un impact humain intensif.
L’article applique des méthodes variables pour décrire et classifier les dunes de sable de l’aire d’étude en utilisant des caractéristiques morphologiques et morphométriques. Aprés une définition des différents types de dunes et de leurs paramétres, il fut possible de sélectionner ces dunes qui étaient exposées á un impact anthropique important pendant differentes périodes á différents endroits.
Sept types de dunes furent séparées: tranchantes, d’apparence parabolique, paraboliquesremplies, paraboliques vides ou partiellement remplies, monticules de forme ovale, crétes de sable. Considérant la hauteur relative et le rythme de la moitié des dunes érodées (52%), on tombe dans un rayon de 1 km á proximité des établissements passés et présents. Un rapport bien determiné fut prouvé entre l’intensité de l’impact humain sur l’environnement et le taux d’érosion sur des dunes de sable immobiles á différents sites-tests.
Pour davantage d’application, la méthode est recommandée pour des régions oú la surface est couverte de matériaux meubles et oú les formes du territoire ont été exposées á une considérable influence de l’homme.

Mots clefs

Impact humain, erosion, morphométrie de dune, classification des dunes, association de dunes paraboliques, Hongrie

Introduction

Numerous environmental and geomorphological research focuses on the way and rate of landscape evolution. One of the most frequent questions is to what extent natural processes are influenced by human impact.
The aim of the present research is (1) to describe the morphological and morphometric characteristics of sand dunes in the South Nyírség Region, (2) to identify different dune forms and classify them in separate dune-types, then on the basis of this (3) to select dunes that were exposed to significant anthropogenic impact, and finally (4) to determine both spatially and temporally the nature and intensity of human activity. Following the method above environmental scientists may find a tool for identifying those places within a slightly altered natural environment that were transformed by a long-lasting human activity. The objectives of the study can be applied in areas where human influence has altered slope conditions and geomorphological features.

The studied area of the Nyírség Region, NE-Hungary, is one of the largest fixed-sand dune areas of the country. The main aeolian activity on the territory came to an end in the Late Pleistocene (Borsy, 1980, 1991), while, at some places the sand kept moving even in the Early Holocene (Kiss, 2000). Later the parabolic sand dunes were completely fixed by vegetation. Erosion still had an effect during the last 10 000 years, especially the sand dunes which faced increasing human influence. In case of the study area the mentioned human influence stands mostly for agricultural activity, since higher dunes are traditional places of vineyards and orchards, while smaller ones have always been used as pasture lands or plough-fields. Former sediment-trap measurements proved that the erosion on cultivated dune-slopes is greater by one order of magnitude, than on slopes covered by forests or undisturbed grasslands (Kiss, 1998, 2000a). Therefore, the longer the dune has been under cultivation or human influence, the lower and more eroded it has become. To verify the hypothesis morphometric measurements were carried out with various methods on more than 1000 sand dunes.
The basic idea was that the original or formational height of a dune is closely related to the dune’s morphogenetical type. First the dunes were classified on the basis of their morphometric parameters and grouped in morphogenetical dune types. Then their present height conditions were also determined in order to select those which were supposedly under long lasting human influence. Finally, to verify the method, three smaller test sites that were affected by human influence to a different degree were selected. The process of verification was supported and supplemented by historical and carthographical data.

Study Area

The southern part of the Nyírség fixed sand dune area (Fig. 1) was chosen as the place of interest for the following reasons:
• The density of dunes is high (2.4 dune/km2)
• In terms of relative height conditions the dunes represent a great variety.
• The time and length of human influence within the chosen territory also varies: (a) there are 1000 year old settlements, (b) medieval villages destroyed by the Turkish Army in the 16th century and (c) relatively newly founded villages.

Fig. 1. Location of the study area

The territory of the study area is 430 km2, its eastern boundary is the Hungarian-Romanian border and the border of the Nyírség, the other three boundaries were set arbitrarily. The whole territory slightly slopes towards south-west, which results that the absolute height of the dunes in north-east exceeds 150 m, while in the south-western corner of the territory dunes hardly reach a 105 m height (Fig. 2).


Fig. 2 Relief map of the study area and the settlement network

The study area is covered by 1049 fixed sand dunes, but only 24.4% of them can be regarded as dominant landforms. The Late-Pleistocene sand dune area of the South Nyírség is characterised by the parabolic dune association, formed on wet-sand (David, 1977). Prime forms are parabolic dunes, the material of which originates from blow-out depressions. First, blown sand accumulated in oval shaped sand hummocks, which later left behind their depressions and transformed into parabolic dunes (Borsy, 1974, 1980). The next step of sand dune evolution was when the eastern wing of a parabolic dune, moved by north-westerly winds, reached the wet abandoned river beds of NE-SW direction. However, the head along with the western wing moved further SE, thus straightening the parabolic dune (Borsy, Z. 1961, 1974). Despite the fact that the migration of the straightened parabolic dune after reaching the wet riverbed ceased, it still received abundant sand supply from behind, thus making it higher, and after all the former parabolic dune metamorphisized into a large edge dune. Beside the above mentioned prime forms, other members of the parabolic dune association can also be identified on the study area. These are narrow and shallow blow-out depressions, smaller windrifts, oval shaped sand hummocks and residual ridges (Borsy, 1980, 1991). Interdune areas are dominated by larger enclosed depressions and long valleys, stretching from NNE to SW. These valleys were the last active river channels of the Nyírség alluvial fan (Borsy, 1980), and until aeolian activity co-existed with fluvial accumulation during the Late Pleistocene, they fundamentally influenced the evolution of aeolian forms.

According to archaeological findings, the territory of the Nyírség Region has been inhabited since the Neolithic Period, however, the first permanent settlements date back only to 1000 A.D. The spatial distribution of the findings reflects that the Neolithic tribes preferred the top of the dunes for living (Kalicz, 1970), and mainly followed a slash-and-burn agriculture, while animal breeding appeared in the Copper Age. Nevertheless, in the Bronze Age the territory was abandoned because the quality of sandy soils on the dunes was very poor and interdune areas were covered by swamps. The Hungarians started to settle down in the region at the beginning of the 10th century (Jakó, 1940). Although, during the Turkish Occupation (16-17th centuries) the settlements were abandoned. Later the families returned, but many of the former villages remained deserted (Szendrey, 1984) and formerly cultivated lands were reoccupied by forests. From the 15th century on orchards and vineyards were the most common types of land-use on the southern slopes of dunes (Zoltai, 1934), and from time to time this lead to disastrous soil loss.

Method

1. Determination of morphological and morphometrical elements
As the first step of the morphometric analysis it had to be determined what morphological parameters (Table 1., Fig. 3.) are characteristic for the different members (Fig.4-5.) of the parabolic dune association (David P.P. 1977, 1981). The main elements identified can be detected generally. There are, however, some additional elements which do not appear in all the dune types.

Table 1. Morphological elements of parabolic dune

Fig. 3. Morphological elements of parabolic dunes

Fig. 4. Dune classes based on the openness of the dune
A.: Open parabolic dune B.: Closed parabolic dune

Fig. 5. Dune types based on the degree of accumulation between the wings. A.: Unfilled dune B.: Partially filled dune C.: Filled dune

For the geoinformatical classification of the dunes we used the following parameters (Fig. 6):
A = Area (occupied by the head and wings)
C = Contour
La = Length of arch (the distance between the termination of the wings along the summital points)
LCh = Chord (shortest distance between the terminal points of the wings)
W = Average width (area/length of arch)
Cu = Curvature (length of arch/chord)
R = Roundness (length of arch/average width)
H = Hackliness (contour/length of arch)

Fig. 6. Arch and chord of a dune

2. Data collection
Field work and cartographic data collection
According to previous measurements (Kiss, 2000a), the eroded material of the dunes is not transported far. Normally, it accumulates at the foot of the dune, rearranging its slope profile, but not altering the area of its cross section (Fig. 7). Therefore, the inclination of sand layers within the dune (original slope angles) and the inclination of the present day slopes on the head and on the slip-face are different. Using the data above and the recent relative height of the dune, the original height can be calculated with the following method:

T’=T where T’ is the area of the present-day cross section
T is the area of the original cross section
The original height (m) can be calculated from present day relative height (m’), the inclination of sand layers in the dune (? and ?) and recent slope angles (?’ and ?’).

m= m’ ? (ctg?’+ctg ?’): (ctg?+ctg ?)

Fig. 7. Parameters for computing the original height of a dune, where m: original height, m’: present day height, ? and ?: inclination of sand layers, ?’ and ?’: recent slope angles

Based on this equation, the gross denudation of the different dune types, both by presuming a natural way of erosion and human influenced erosion, was calculated. Following various measurements on the parameters needed for the equation, present-day relative heights were plotted against the calculated original height (Fig. 8). The studied dunes plotted to two major groups: dunes fitting the upper line were eroded by 4.0-6.5 m, and those along the lower line denuded only by 1.0-2.5 m. Dunes representing the first group are in the neighbourhood of villages, while the rest is situated far away from any settlements. This calculation suggests that dunes under human impact lost three times more from their height, than the undisturbed ones.

Fig. 8. Present-day relative height plotted against calculated original height (dashed lines represent trend lines)

Geoinformatical data collection
The base maps applied for the geoinformatical analysis were of 1:25,000 scale and represented a territory of 430 km2. Following the geo-correction of the sheets under software Arc/Info 7.0.3. and Arc View 3.2. the contour of the dunes was digitised. The contour was defined as the lowest continuous contour-line that surrounds a given form. This way, 1049 dune forms were identified on the whole area. Beside their contours, their arc, chord and the relative height of their summit were determined as well. Finally, water-flows, roads and settlements were also digitised.
The softwares enabled the collection of a large number of parameters, and a database was built on the area, perimeter, length of arc, length of chord and relative height of the dunes. On the basis of these data, the calculation of further parameters became possible.

3. Classification of dunes
The manually or digitally collected and calculated data enabled the geomorphological classification of the forms on the territory. The classification was based on the system of Wolfe S.A. - David P.P. (1997). The separation of dune types in terms of a given parameter was based on the frequency distribution graphs of the parameter.

4. Localisation of dunes under significant human impact
During the morphological classification values of relative height and “hackliness” were not considered, because these parameters refer to subsequent erosion processes. For each dune type the total number of members, their average height, and the number of dunes representing different height groups within the type was determined. Erosion measurements pointed to the fact that the dunes under human impact are 2-4 m lower than the rest. Therefore, during the computer based evaluation we highlighted those dunes that were 2-4 m lower than the type average. Nevertheless, the statistical way of selection may lead to misinterpretation, namely, if the highest dune eroded 4 meters it did not necessary become lower than the group average. To overcome statistical errors further parameters such as “hackliness”, and “rhythm of relative relief” (defined below), which refer to subsequent aeolian activity, had to be introduced to the analysis.
• Hackliness: According to prior research (Borsy, 1991; Lóki, 1985; Kiss, 1998), during historical times due to human impact the aeolian activity restarted on smaller, unvegetated patches in drier periods, and resulted in the formation of blow-out depressions. These depressions altered the original shape of the dune, thus its contour line became hackly. On the basis of calculations, if the index (H) is greater than 2,8 then the dune was reshaped by subsequent aeolian activity. This theoretical threshold was verified by field experiments and sedimentological researches as well (Kiss, 1998, 2000).
• Rhythm of relative relief: On the 430 km2 large research area the dunes form several dune-fields, which are separated by valleys (Kiss et.al. 2003). The highest dunes occur always on the eastern edge of the dune fields, and dunes located in the western part of a field are significantly lower. In addition, a general growth in height can also be observed on the study area in a SE direction (Fig. 9). The reason of rhythmical change in height originates back to the genesis of the whole sand dune area, to the time when aeolian and fluvial activity coexisted (Kiss, 2001). Namely, as the dunes moved toward SSE, the valleys, as mentioned before, could stop their movement and parabolic dunes transformed into edge dunes. If there was a different tendency, the explanation can be revealed by field experiments (Kiss, 2000b).

Fig. 9. Rhythmical change in relative dune height along a NW-SE cross section

The spatial distribution of the selected eroded dunes was compared to the present road and settlement network and former land use in order to control the applied methods for localising areas of heavy human impact. The map series supporting the verification dates back to the 18th century, thus it is possible to identify intensively used lands.

Results and discussion

1. Classification of dunes
The morphometric measurements enabled the classification of parabolic and edge dunes. The dune types separated on the basis of morphometric parameters are listed in Table 2. The spatial distribution of the different dune types is characteristic. Still, the position of edge dunes and edge-like dunes is the most well defined (Fig.10).

Table 2. Dune types and their morphometric characteristics and spatial distribution (abbreviations see in “Methods”)

Fig. 10. Spatial distribution of edge dunes and edge-like dunes

Edge and edge-like dunes are the most abundant dune types on the study area (41% of the total dune area), and most of them appear in two dune-fields on the SE part of the territory. Their number is decreasing westward indicating drier valleys during sand movement. One third of the edge dunes are situated directly on the western edge of the valleys, while the rest of them are aligned behind each other. The longest (3155 m) and the highest (relative relief 18 m) dune in the whole study area also belongs to this group. The mean height of those located next to the valleys is greater than the group average by 1.5 m, and much greater than the mean height of other dune types. The arch of edge and edge-like dunes stretches from NE to SW, and their highest point is in the middle of the arch. The back-slope of some dunes is full of blow-out depressions, the post-genetic origin of which can be justified with the E-W direction of their axes that is different than that of the hosting dunes.
The other third of the dunes (37%) belong to the pseudoparabolic dune type. Most of them appear in groups in the middle and northern part of the study area. They occupy the area between parabolic and edge dunes, in the mid-section of dune-fields (Fig. 11). The axes of these dunes have a NW-SE or NNW-SSE direction. They were also reshaped by post-genetic aeolian activity The direction of blow-out depressions suggests the dominance of western winds at that time.

Fig. 11. Spatial distribution of parabolic dune types

Only three percent of the dunes belong to the types of filled- and partially filled parabolic dunes. Most of them gather in two areas, the rest are dispersed (Fig. 11). Some of them bear the sign of asymmetry, because their summital points are on the southern third of the arch which suggests that they were formed by multidirectional winds, though, the dominant wind in their case was still north-westerly.

Three percent of the dunes are of unfilled parabolic type. They are located in the valleys or on larger flat interdune areas (Fig. 11). Their axes, contrary to the other classes, points southwards showing that they were formed at different geological times. None of the unfilled parabolic dunes were reshaped by blow-out depressions, therefore, they are probably younger than the other dune types, or they were just effectively fixed by vegetation during the Holocene. To decide on this question further measurements (OSL, TL) are necessary.

The large number of oval shaped sand hummocks (13% of the total number of accumulation forms) and short sand ridges (34%) is a bit misleading, because they are very small in size and they represent only the 18% of the total area of dunes. They are scattered all over the study area (Fig. 12), however, many can be found in the west. Their axes are multidirectional, i.e. in the western half of the study area mostly N-S, while in the other parts NW-SE.

Fig. 12. Spatial distribution of other dune types

2. Localisation of dunes under significant human impact
Spatial distribution of dunes altered by human activity
Morphometric parameters give indirect information about the environmental conditions existing during the development of sand dunes, e.g.: the amount of sand supply, density of vegetation, ground-water level (David, 1979, 1981; Lemmen et al., 1998) or postgenetic human influence.

At this stage of the analysis some additional morphometric conditions (relative height, hackliness, rhythm of dunes) referring to subsequent erosion were also considered when creating the proper selection of dunes (Fig. 13). At some places the eroded dunes proved to be more abundant than at others. After overlapping the selection of erode dunes with the place of former and present settlement network it became clear that more than half (52%) of the eroded dunes are within the 1 km vicinity of villages. The increased density of eroded dunes around villages is even more evident if we consider that the territory of these areas is only 11 % of the whole study area, however, more than half of the eroded dunes occur here. All these facts suggest that the method is precise enough to locate territories where human impact was significant.

Fig. 13. Spatial distribution of dunes under heavy human impact

Temporal variation of human impact on dunes
The different rate of human influence in time and space can be best studied when examining the changes occurring on well defined test areas. Considering the length of use, three main scripts of temporal variation can be set up in the research area (Fig. 14.):
a) Continuously inhabited villages since the Árpád Period (11-13th century), like Bagamér, Álmosd or Vámospércs
b) Villages founded in the 11th century but deserted during the Turkish Occupation (16-17th c), like Bánk, Haláp, Fancsika, Nagycsere, Pac etc.
c) Villages established in Modern Times (e.g.: Újléta)
With the help of archaeological and archival findings and the available maps (1793, 1884, 1939, 1970) it was checked whether the selected dunes were under intensive human impact or not. In addition, the rate of stress in different historical periods was also estimated. The same approach was applied in terms of each village when determining their role in environmental change. In the following section the most typical representatives of the three scripts will be introduced.

Fig. 14. Former and present day settlement network of the study area

a) Bagamér
The village was founded on the border of the Nyírség and Érmellék Regions in the 13th century (Jakó, 1940). Contemporary documents report on forest clearances around the village. In the 15th century a new period of forest clearance and grape-plantation started (Jakó, 1940). Two centuries later the village became the most densely inhabited settlement in the area, therefore, by the end of the 17th century it was raised to a town status. Due to the Mongol and later the Turkish invasion, Bagamér lost its population, and by the beginning of the 18th century only 12 families lived in the village, thus it ceased to function as a town. During the wars the fields became “praedium, desertum”(left behind land), only some hidden fields were cultivated and the number of livestock decreased radically. According to the first conscription (1713), Bagamér played an important role in vine export, though in 1840 only 1,7% of its territory was occupied by vineyards, suggesting rather intensive human impact on small patches of land (Penyigei, 1980).
The map of the First Ordinance Survey (1783) shows a parkland in the NW corner of the test area, whilst in the west a dense forest can be seen (16%) (Fig. 15 A-B). On the map of the Third Ordinance Survey (1884) only the NE corner of the test area is covered by forests (10 %). Meadows and pasturelands replaced them at other places. The third map from 1939 indicates reforestation on the northern part. The territory of vineyards and orchards increased continuously (up to 19%), and they have always occupied the eastern, highest members of the dune-field. Throughout the past centuries, they have stretched further and further away from the settlement, sometimes as far as 3-4 km.

Fig. 15. A-B. Land-use changes in the environs of Bagamér during the last 200 years

After overlapping this map series with the map of eroded dunes (Fig 13), it is obvious that human impact was the most intensive on (1) dunes in the close vicinity of the village and (2) on those that are situated SW of Bagamér. The dunes next to the village (1) are the traditional places of the vineyards, gardens or plough- and pasturelands. Thus, these are the most eroded dunes among all, especially those, which were used for the longest time. The relative height of these dunes is 4-6 m, which is much less than it should be on the basis of the height-rhythm of dune fields, which predicts a 15-18 m height for them. Also, they are lower than the average of their morphological type by 2-3 m. The other territory (2) was influenced by human activity much later. Here the dunes are slightly lower than their type-average, yet, they should be much higher as they are on the eastern edge of the dune-field.

In all, on the Bagamér test-area the eroded dunes separated by morphometric measurements correspond well to the intensively used parcels described in archives and shown on the map series.

b) Haláp
A good representative of villages that once were densely populated, but were abandoned later, suggesting that the rate of erosion probably altered significantly during history. The village of Haláp was founded in the 13th century and soon became the centre of its region. A document from 1553 mentions that the territory of clearances (meadows) increased rapidly at that time and on the deforested patches aeolian activity started (Penyigei, 1980). Haláp became uninhabited several times, and finally it became completely abandoned at the beginning of the 17th century (Kiss, 1962). The new owner of the land, the city of Debrecen, had to pass an act about the protection of forests in 1638 to prevent overgrazing and burning (Penyigei, 1980). At this time 58% of the territory was covered by forests. From the 1820’s on farms appeared in the area and farmers started new, uncontrolled forest clearances, therefore, both the territory and quality of forests decreased significantly. The second modern wave of immigration started between the1860’s and 1880’s reducing the area of forests and meadows and replacing them with plough-fields. More recently, Haláp is a centre of Debrecen’s outskirts, but the new village was rebuilt at a different site than that of the medieval settlement.

The latest changes above are well presented on the map series (Fig. 16.A). The first map of the test area was made in 1771 (Geometrica Delieatio Praedii Haláp). Subsequent maps (1884, 1939) show not only the reduction of forests by 15 % (Fig. 16.B), but also that the woodland population became less dense, and meadows, pasture-lands and plough-lands intruded the uniform forest areas. The medieval village was situated in the centre of the test area, where the mean height of the parabolic dunes is only 5-7 m, which means they are lower than the type-average by 1-3 m. Furthermore, these dunes were reshaped by postgenetic aeolian activity. Further from the medieval village the relative height of dunes is increasing (up to 9-13 m), indicating smaller human impact.

Fig. 16. A-B. Land-use changes in the environs of Haláp during the last 200 years

Compared to the test area of Bagamér, the most significant difference in this case is the fact that the erosion caused by medieval agricultural activity ceased after the desertion of the village in the 17th century. The result of this is that the dunes remained higher. Still, erosion is greater than it could be expected on the basis of the length of landuse, which can be explained with the more intensive medieval agricultural practice.

c) Újléta
Újléta was established in 1865 (Süli-Zakar, 1999) and is now a small village, with less than 1000 inhabitants.

The First Ordinance Survey (1783) shows forest patches on the top of the dunes, while the rest of the test area is covered by grasslands and groves (Fig. 17.A). On the 1884 map the vicinity of the village is woodless, whilst SW of the village newly established vineyards are shown. In 1939 the territory of forests was reduced even further (during 150 years by 19%), and the territory of plough-fields and vineyards increased greatly(Fig. 17.B). Between 1939 and 1970 the proportion of different land uses changed just slightly. The dune that is east of the village belongs to the edge type of dunes, the other dunes are edge-like dunes and pseudoparabolic dunes. On the test area only one dune is lower than the mean of its morphological class, the height and form of the other dunes show natural erosional processes.

Fig. 17. A-B. Land-use changes in the environs of Újléta during the last 200 years

Hence, it can be clearly seen, that modern agricultural techniques result in far less erosion than medieval land use, however, the area of cultivation has increased by time. The differences in erosion can be explained not only by the different techniques, but also by the short period of human influence. In this case the morphometric measurements do not give satisfactory results on the exact place of human activity.

Conclusions

The wide set of applied methods made possible to extend our in-situ geomorphological measurements to a larger (430 km2) area. The results might be summarised as follows:

• The morphometric measurements and the geoinformatical analysis enabled the classification of the numerous fixed sand dune forms of the South Nyírség Region. Seven dune types were separated: edge, edge-like, pseudoparabolic, filled parabolic, partially and unfilled parabolic, oval shaped hummocks, sand ridges.

• With the help of additional morphometric parameters, such as relative height, hackliness and rhythm of the dunes, the selection of dunes under long lasting human impact became possible. Dunes that did not correspond to the mean height of their type (sometimes 4-6 m lower), or show a hackliness index greater than 2.8 or misfit the expected height based on the rhythm of the dunes were declared as landforms exposed to under significant human impact. More than a half (52%) of the eroded dunes fall within the 1 km vicinity of former and present day settlements.

• There is a definite connection between the intensity of human impact on environment and the rate of erosion (lowering) on fixed sand dunes. The approximate rate of erosion on human influenced dunes was 1-1.5 m/100 years during the Medieval ages and 0.5 m/100 years recently.

• The preconception that human influenced dunes can be localised on the basis of their morphometric parameters proved right after controlling geoinformatic data with archives and contemporary map series. The method might be used in other areas where the surface covered by loose materials and the landforms have been exposed to significant human influence.

References

Borsy, Z. 1961: A Nyírség természeti földrajza. (Physical geography of the Nyírség) Akadémiai Kiadó.p. 227

Borsy, Z. 1974: Recent results of wind-erosion studies in Hungarian blown-sand areas. Földrajzi Értesíto, Vol. 23. pp. 227-236.

Borsy, Z. 1980: A Nyírségben végzett geomorfológiai kutatások újabb eredményei. (New results of the geomorphological research in the Nyírség) Acta Academiae Pedagogicae Nyíregyháziensis, Tom. 8/F, pp. 19-36.

Borsy, Z. 1991: Blown sand territories in Hungary. Zeitschrift für Geomorphologie N.F. Suppl. 90. pp. 1-14

David, P.P. 1972: The Brookdale Road Section and its significance in the cronological studies of dune activities in the Brandon Sand Hills of Manitoba. The Geol. Ass. of Canada Special Paper No. 9. pp. 293-299

David, P.P. 1988: Sand dune occurrences of Canada: a theme and resource inventory study of eolian landforms in Canada. Indian and Northern Affairs, National Parks Branch, Contract No. 74-230. pp. 183.

David, P.P. 1977: Sand dune occurences of Canada: a theme and resource inventory study of eolian landforms in Canada. Indian and Northern Affairs, National Parks Branch, Contract No. 74-230. pp. 183.

David, P.P. 1979: Sand dunes in Canada. GEOS Spring, Dept. Energy, Mines Resources, Ottawa, pp. 12-14.

David, P.P. 1981a: Stabilized dune ridges in northern Saskatchewan. Canadian Journal of Earth Sciences, Vol. 18. pp. 186-310.

Jakó, Zs. 1940: Bihar vármegye a török hódoltság elott (Bihar County before the Turkish Occupation) pp. 340.

Kalicz, N. 1970: Agyagistenek (Neolithic and Bronze Age findings in Hungary). Corvina Könyvkiadó pp. 78.

Kiss, T. 1998: Recent erosional measurements in the Erdospuszta – near Debrecen. in: Acta Geographica ac Geologica et Meteorologica Debrecina, Tomus 24. pp. 151-165.

Kiss, T. 2000a: Erosional measurements on parabolic sand dunes. in: National Conference of PhD Students III. Debrecen, pp. 21-32.

Kiss, T. 2000b: Human influence on environmental change – reserach on an interdune area in the South-Nyírség. Acta Geographica Szegediensis, Tomus37. pp. 55-67.

Kiss, T. 2001: Selection of parabolic dunes effected by long-term human activity. In: Füleky Gy. (edt) Landscape Changes in the Carpathian-basin due to historical events pp. 205-211.

Kiss, A. 1962: A debreceni késo középkori vaseszköz lelet. (Late Iron Age findings at Debrecen) A Debreceni Déri Múzeum Évkönyve. pp. 29-37.

Lemmen, D.S. - Vance, R.E. (eds.) 1998: Geomorphic systems of the Palliser Triangle, Southern Canadian Prairies. Geological Survey of Canada Bulletin 521. p. 25-39.

Penyigei, D. 1980: Debrecen erdogazdálkodása a XVIII. században és a XIX. század elso felében. (Forestry in Debrecen during the 18-19th centuries) Agrártörténeti tanulmányok 7. Akadémiai Kiadó

Süli-Zakar I. et al 1999: Hajdú-Bihar megye monográfiája (Hajdú Bihar County) p. 325

Szendrey, I. 1984: Debrecen története 1693-ig. (History of Debrecen until 1693) p.29-99.

Wolfe, S.A. - David, P.P. 1997: Parabolic dunes: examples from the Great Sand Hills, SW Saskatchewan. Lé Géographe canadien 41. No. 2. pp. 207-213.

Zoltai, L. 1932: Amikor még Debrecen környékén is sok volt az erdo. (Once dense forests covered the neighbourhood of Debrecen) Debreceni Képes Kalendárium pp. 1-7.

Please cite this paper as:
Kiss, T., Sipos, G., Bódis, K. and Barta, K. (2004) Selection of human influenced sand dunes on the basis of morphometric measurements, South Nyirseg region, Hungsry, International Journal of Fieldwork Studies, 2(1), http://www.virtualmontana.org/ejournal/vol2(1)/dune.htm