Supervisors info:
Ν. Ευελπίδου, Επ. Καθηγήτρια ΕΚΠΑ, Χ. Μαρουκιάν, Καθηγητής ΕΚΠΑ, Δ. Λέκκας, Επίκ. Καθηγητής Παν/μίου Αιγαίου
Summary:
This thesis concerns the estimation and management of flood risk in the
drainage basin of Paratrechos or Peritsi stream in Naxos Island, through the
study of geomorphological characteristics, geology, land use and topography.
The catchment area of Paratrechos or Peritsi stream is approximately 54 km2.
High morphological relief characterizes the mountainous areas while lowland
areas present mild relief. The average elevation reaches 245 m and the average
slope of the basin is 21%.
Naxos Island constitutes part of the Atticocycladic unit, and it could be
described as an elliptic dome, of NE direction, that consists mainly of
metamorphic schist rocks, gneiss, marbles and Neogene and Quaternary deposits.
In the core of the dome lies the migmatite intrusion. The catchment area is
drained by a medium to dense hydrographic network, which presents medium to
intense meanders at some locations.
The stream is known to have caused severe problems following intense rainfall,
with landslides in the mountainous areas and subsidence in large parts of the
road network, and with intense flooding events in the wider area of Chora of
Naxos. Several floods have been recorded for Paratrechos or Peritsi stream,
with the most recent ones at the end of March 1998, beginning of January 1999
and 18th February 2003.
The aim of this thesis is the investigation of the relationship between
rainfall and the arrival time of runoff at the river month, through Unitary
Hydrographs, in order to estimate and evaluate the flood potential of the
hydrologic basin.
In order to obtain accurate results, the hydrologic basin was divided into
sub-basins, based on the class of each stream, and the characteristics of each
sub-basin were studied. For the optimum application of the Clark method, the
data were enriched with field measurements, through the installation of a water
level recorder and a meteorological station. The results from the field
measurements were used to confirm the results from the method.
Through this method, the maximum flow at the mouth of each sub-basin and the
concentration time were calculated. Maps of flood risk were developed, with the
use of ArcGis 9.3 software, presenting the characteristics of the flood risk
locations in the study area. Furthermore, Instantaneous Unit Hydrographs were
produced for each sub-basin, in order to study and compare the relationship
between rainfall and the arrival time of runoff at the river month and
determine the causes of the risk. The identification of these areas and the
application of the method were accomplished through the study and use of
contours, elevation and trigonometric points, watersheds, land use,
hydrographic network, soil characteristics, geological characteristics and
flood picks.
Keywords:
Flood, Risk, Catchment , Unitary Hydrographs, Clark method
