The object of this study is to depict and evaluate the methods and techniques implemented or scheduled for the anti-erosion - anti-flooding protection in mountainous drainage basins in Evrytania, which exhibit intense erosion phenomena and constitute a danger of flooding for the downstream areas. Among these areas are also inhabited areas, such the town of Karpenisi, and for this reason the optimum way of management of these drainage basins constitutes an important element for the development of the town and also for the "sustainability" of the greater area (Evrytania, Greece)

Kosmas, A.

Kosmas, S.

Marabini, Francesco

Mertzanis, A.

Papadopoulos, A.

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CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 220 
METHODS & TECHNIQUES FOR THE ANTI-EROSION AND 
ANTI-FLOODING PROTECTION IN MOUNTAINOUS DRAINAGE 
BASINS IN EVRYTANIA (GREECE) 
 
Α. Mertzanis1, S. Kosmas2, A. Papadopoulos1, A. Kosmas3 and F. Marabini4 
 
1 Technological Educational Institute of Lamia, Department of Forestry and 
Management of Natural Environment, 36100, Karpenisi, Greece, amertzanis@teilam.gr  
2 Forest Directorate of Evrytania, 36100, Karpenisi, Greece 
3 Engineer of Planning and Regional Development, 36100 Karpenisi, Greece 
4 National Research Council, ISMAR, 101 P. Gobetti str., 40129, Bologna (BO), Italy 
 
 
Abstract 
The object of this study is to depict and evaluate the methods and techniques 
implemented or scheduled for the anti-erosion - anti-flooding protection in 
mountainous drainage basins in Evrytania, which exhibit intense erosion 
phenomena and constitute a danger of flooding for the downstream areas. Among 
these areas are also inhabited areas, such the town of Karpenisi, and for this reason 
the optimum way of management of these drainage basins constitutes an important 
element for the development of the town and also for the “sustainability” of the 
greater area (Evrytania, Greece).  
 
1. INTRODUCTION   
The development and expansion of parts of towns, villages and dwellings 
in areas close to the streambeds of torrents, can cause flooding, especially in the 
cases where these torrents exhibit intense hydrogeomorphological erosion and 
sliding phenomena in their drainage basins (Kotoulas D. 1972, Kotoulas D. 1987, 
Kotoulas D. 2001, Sapountzis M., et al. 2006). A significant amount of weathered 
materials are detached from the slopes of the mountain Timfristos and in conditions 
of repeated downpour or snowfall, are transferred via the torrents and are deposited 
in the areas downstrem. Amongst the drainage basins that exhibit increased 
geomorphological “vulnerability” where we see intense geomorphological 
weathering - erosion processes in the geological formations that compose them, 
there are some (drainage basins), the beds of the torrents that drain them, run 
through inhabited areas such as villages, dwellings areas, towns like in a part of the 
town of Karpenisi, in the neighboring dwelling of Xiria in the east and the village 
of Agia Triada. 
CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 221
 
2. MATERIALS AND METHODS 
2.1 Geographical location of the study area 
The greater study area is located at the mountain Tymphristos in Evrytania 
and more specifically at altitudes of 700 meters and above. The torrents under 
study Klarotos and Kakorema, drain their drainage basins which are formed in the 
south slopes of the Tymphristos mountain in Evrytania, they run through the town 
of  Karpenisi and the eastern part of the alluvial fan respectivelly, where the 
dwelling of Xiria is located. At the north slope of the Tymphristos mountain, the 
Agia Triada village is crossed at its boundaries east and west by the torrents Poros 
and Neraidias. 
 
2.2 Investigation method 
For the depiction of the existing situation of the natural environment of the 
under study drainage basins, as well as for the depiction of the dynamic hydro-
geomorphological activities and of the technical and geological characteristics that 
are formed, there were used topographical, geological and vegetation maps, and 
meteorological and hydrological data as well as relevant studies which were 
obtained from the Forest Authorities of Evrytania. 
 
3. RESULTS - DISCUSSION   
The unfavorable climatic conditions which prevail at the drainage basins of 
the upper flow of the torrents Klarotos, Kakorema, Poros and Neraidias combined 
with the high slopes (>50%), increase the “trailing” ability of the flowing waters 
and favor the formation of intense axial (ravinal) and slope erosion with significant 
undermining at the of the foot of the slopes. An important fact is the appearance of 
widespread phenomena of surface erosion due to “hydrolayer flowing” where the 
fine aggregates drift, while the coarse -voluminous materials remain in place. 
The torrent Klarotos that runs through the town of Karpenisi exhibits 
potentially increased geomorphological “vulnerability” and the possibility of 
flooding incidences. Similar characteristics as far as the geomorphological 
“vulnerability” and the possibility of flooding incidences are also noted, 
downstream, in the case of torrent Kakorema which discharges into the river 
CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 222 
Karpenisiotis , through the alluvial fan where we find the dwelling of Xiria. It is 
noted that the greater area of the alluvial fan exhibited in the past occasional 
incidences of flooding, and consists an area which in the future it is possible to face 
flooding problems, due to unfavorable hydro-geomorphological conditions which 
occur in the area and due to the presence of the Kakorema torrent, of which the 
preservation of its streambed in the east end of its alluvial fan requires systematic 
monitoring and preservation works. The torrents Poros and Neraidias which run 
through the village of Agia Triada in the north slope of the Timfristos mountain, do 
not exhibit increased geomorphological “vulnerability” and with the exception of 
extreme climatic - hydrogeomorphological phenomena and processes, we do not 
expect serious problems. 
 
 
 
Fig. 1a & 1b -  Works for the settlement of the torrent Klarotos. Stone dam for the 
settlement of branch Kotronakia (1a). Picture 1a shows the extra elevation of the 
dam in order to make it more efficient. Artificial sheeting of the bed of the torrent 
Klarotos in the town of Karpenisi (1b). (Source: Α. Μertzanis) 
 
CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 223
The works for the re-direction of the torrent Klarotos the first of which 
were constructed already since 1956, by the Forest Authority, were successful. The 
streambed was “secured” since it acquired fixed points the ravine and gradient 
erosion and the sliding and land sliding were put under control and until recently 
the torrent did not create any flooding problems in the town of Karpenisi, given 
that, that from time to time the initial works were enforced with complementary 
smaller scale works which were constructed during the 1971, 1980, 1984, 1987, 
1997 and 1998 (Figures 1a & 1b). The works for the re-direction of the torrent 
were constructed only up to the base of the steep slope, due to technical difficulties 
and also due to the coarseness of the relief (Kosmas S., et al. 2009).  
 
4. CONCLUSIONS   
In order to avert the evolution of the torrential phenomena, the ravine 
erosion and the deepening of the central streambed which causes the breakdown of 
the gradients which is worsened by the nature of the geological substrate, what is 
needed to be done, is to make a continuous effort for the “fixing” of the streambed 
in the upper part upstream of the last dam. Also it is needed to repeat the planting 
works in order to replenish the vegetation  so that the surface erosion-weathering  
which supplies the streambed with materials can be restricted and also so that the 
volume of the flooding flow can be reduced. For the planting works  (reforestation 
and re-grassing), to be effective first it is necessary to stabilize the ground of the 
gradients by constructing “small walls” and  “dry walls” at the slopes and at 
locations where small sliding is seen inside the ravines. The use of machinery 
necessary for this work in these locations is not possible, due to steep 
morphological gradients which form the relief of the basin combined with the 
greatly weathered and eroded and gliding soils. The construction of new roads in 
order to make the area accessible so that the materials needed can be transported is 
expected to burden even more the situation and further aggravate the erosion-
gliding phenomena (Ministry of Agriculture, 1971, Ministry of Agriculture 1983). 
These averting factors, formulate the context of the implementation of the 
suggested works of stabilization-restoration of the gradients (reforestation, re-
grassing, agrotechnical), the construction of which presupposes manual work, 
while in actual fact the implementation of more effective techniques is not 
CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 224 
possible: α. Hydro seeding in combination with filling with straw, hydraulic hydro 
seeding, hydro seeding with the use of a three dimensional grid etc (presupposes 
the use of hydro seeder), b. Covering of the gradients with grid – geo cells and  
vegetive soil and c. fences for the containment of rainfall etc. 
Finally, for the completion of the works for the aversion of torrential 
phenomena and for the management of  flooding incidences in the town of 
Karpenisi, the  restoration of the damage of the top  and the flaps of the old dams 
which was caused during the 30-40 years from their initial construction as well as 
from the damage caused by the flowing and crashing materials, from the flowing 
waters, large stones, and smaller size dry dragged materials is expected. For their 
more efficient function there will be constructed in the between, parallel walls 
made of concrete and wiredrawn boxes, dry stonework made from collected stones, 
as well as a new dam, while for the construction of the works in the upper part of 
the basin (at Kotronakia) we need to expand the existing road. In the long run, the 
study group thinks that new dams should be constructed amongst the old ones, in 
order to further decrease the slope of the bed and increase its width so the speed of 
the flowing waters and as a consequence the transport ability of the torrent will be 
further restricted. An important priority is the prohibition of grazing which should 
be continued for the years to come and the strict control of prohibition. 
 
REFERENCES 
Kosmas S., Papadopoulos A., Mertzanis A. and Kosmas A. (2009). “The 
effectiveness of works of mountainous water-regulation – antifouling protection, at 
the upper flow of torrent Klarotos (Evrytania)». Proceedings of the 14th Hellenic 
Forest Convention, - Hellenic Forest Society, 01-04 November 2009, Patra (in 
Greek). 
Kotoulas, D. (2001). “Mountain Hydronomy”, Volume Ι. The flowing waters. p. 
681. Thessaloniki (in Greek).  
Kotoulas, D. (1987). “Re-direction of Torrential currents”, Volume ΙΙ. p. 100 
Dynamic torrential types. Thessaloniki (in Greek).  
Kotoulas D. (1972). “Die Wildbache Sűddeutschlands und Griechelands”. Teil 1. 
Bericht nr. 25 der versuchsanst. f. Wasserbau d. T.U. Műnchen.  
Ministry of Agriculture / General Directorate of Forests (1971). “Final study of 
Klarotos Torrent: P. Skaltsas and Κ. Haralambous. Athens (in Greek). 
CHINA-ITALY BILATERAL SYMPOSIUM ON THE COASTAL ZONE AND CONTINENTAL SHELF EVOLUTION TREND 
October 5-8, 2010 - Bologna (Italy) 225
Ministry of Agriculture / Directorate of Reforestation and Mountain (1983). “The 
torrential basins in the context of hydrographical network Athens (in Greek). 
Sapountzis M., Papathanassiou T., Mertzanis A., Efthimiou G., Aggelakopoulos I. 
and Myronidis D. (2006). Water erosion and geomorphology in the watershed of 
torrent “Gerampini” Zagora, Pelion, Bulletin of the Hellenic Geological Society, 
Volume XXXIX/III-1, p. 104-118 (in Greek). 
 


Methods & Techniques for the Anti-erosion and anti-flooding protection in mountainous drainage basins in evrytania (Greece)

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Methods & Techniques for the Anti-erosion and anti-flooding protection in mountainous drainage basins in evrytania (Greece)

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