Joint International Conference on Long-term Experiments ...

At the same time, the genesis of floods is indirectly linked to the geological factor: the
lythology and the structure both influence the movement of water and the development
of the type of drainage.
Because of its hydrical and physical properties, the soil is an important factor
regarding water flow on its surface. The vegetation acts directly upon discharge by
influencing the regime of soil humidity, and indirectly by protecting against erosion .
Antropic activity acts against the genetic factors of flow (by clearance, plantation,
pasture etc.) on the one hand, and against the flow from the riverbed on the other hand
(by the mitigation of debits, embankments, water consume usages).
MATERIALS AND METHODS
To emphasize the territorial and temporal differences between the floods of the Almaş-
Agrij Depression and the floods of the Cluj and Dej Hills, there were analysed and
processed data that originate from nine hydrometrical station: Almaş, Hida, Românaşi
(Almaş-Agrij Depression), Căpuşu Mare, Mera (Rădaia), Aghireş, Maia, Borşa and
Luna de Jos (Cluj and Dej Hills) on the: Almaş, Agrij, Căpuş, Nadăş, Olpret, Borşa and
Lonea rivers. The data are resulted from the observations and measurements performed
over a period of 28 years (between 1976 and 2004), and they are archived in the Annual
Hydrological Studies of the Somes-Tisa Water Department of Cluj-Napoca.
The time frequency of floods within the studied time interval on the rivers of
Almas- Agrij Depression and Cluj-Dej Hills has been analysed based on these data. The
seasonal frequency of floods has been graphically represented, calculating the total
number of floods in each season at each hydrological station. The monthly frequency of
floods has been represented the same way using the same method, the calculation being
made for each month.
Then, also based on these data, it were described two types of parametres of flood
(the maximal debit and the duration). The main characteristic parameters of a flood are:
debits (maximum debit, base debit), duration (total duration or total time, increasing
time, decreasing time), water volumes, the form coefficient of flood, the medium flowed
layer, etc. Maximum debit ( Qmax m 3 /s) represents the parameter of the maximum
interest, because this is the moment of the biggest danger, the maximum overflow. The
duration of floods is an important element of which depends the size of the effects
which could be generated (Sorocovschi, 2005). The whole duration or total time is
composed by increasing time and decreasing time
The maximal debits ( Qmax ) of floods on the rivers of Almas-Agrij Depression and
Cluj-Dej Hills have been graphically represented for the period between 1976 and
2004. The years with highest and lowest risk of inundations have been clearly
underlined.
The total duration (Tt) of the flood has been obtained by calculating the number of
hours, from the time when the debit overpassed the basic debit, until the time it came
back to the value of the basic debit (of course, after reaching the maximal debit - Qmax).
The increasing time of flood has been obtained by adding the number of hours
from the time the debits started to grow until the time the maximal debit (Qmax) has been
recorded.
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