RESULTS OF MONITORING TORRENT CONTROL HYDROTECHNICAL STRUCTURES IN THE CÂRCINOV RIVER WATERSHED

„TRANSILVANIA” UNIVERSITY BRASOV
           FACULTATEA OF SILVICULTURE AND FOREST ENGINEERING

     RESULTS OF MONITORING TORRENT-
  CONTROL HYDROTECHNICAL STRUCTURES IN
      THE CÂRCINOV RIVER WATERSHED

Authors:
Nicu-Constantin TUDOSE
Mihai-Daniel NIŢĂ
Ioan CLINCIU

Legal framework

      Water Framework Directive (adopted by the European Committee in 2000)
formulates the objectives of increasing the availability and quality of water
resources and of attaining the sustainable use of waters in EU countries by 2015.
Diminishing of drought and flood effects is among the major problems considered,
reflecting high frequency and significance of these events.

      In Romania, the national flood risk management strategy was adopted at the
end of 2005. It formulates the following objectives for the National Authority for
Silviculture:
• mapping the forest areas on torrential flood vulnerability criteria
• investigating the functioning of torrent-control structures
• elaborating a national program for managing torrential watersheds
• sustainable management of forests.

Research location
      Research was performed in the Cârcinov River watershed in order to characterize the
functioning of hydrotechnical structures.
      The study area is located in the southern part of the Meridional Carpathians and is
characterized by a high-energy landscape. The area is underlain by cross-stratified rocks,
marls and sandstones, covered with a 3 to 5 m thick layer of loess deposits.

Research methodology

     Because the functioning of torrent-control hydrotechnical structures
cannot be verified in laboratories (because of the encountered difficulties in
reproducing the phenomena from torrent valleys in models), field observations
provide the main possibility for monitoring this functioning.

      To collect data refering to the functioning and effects of hydrotechnical
structures situated in a managed torrential valley from the upper Cârcinov River
basin, the structures and their component parts were identified according to a
standard form (Clinciu 2003).

Register card
Component parts of a structure were
considered the physical parts, which
compose      the   construction     and
functional parts (e.g. apron, spillway,
etc.) or those valley areas, which
interact with the structure (e.g. the
upstream or downstream area).
The forms were filled in the field,
following visual description of the
structures and their component parts,
more detailed observations and
measurements.
These observations were made in
order to recognize the nature,
frequency      and    proportion     of
various types of events which
occurred during structure functioning.

Descriptive elements of the behavioural
                 events

Cracks

Enhances the infiltration and
accelerates the masonry
degradation.

The are weakening the
resistance and stability in time
for the structure

Descriptive elements of the behavioural
                events

Breakages

They reduce the
hydrotechnical structures’
resistance

Descriptive elements of the behavioural
                events

Undermining the dams’ body

They reduce the
hydrotechnical structures’ and
work resistance resistance's
They put in danger the stability
and the resistance of the work,
when this is not equipped with
supplementary energy
dissipating system.

Descriptive elements of the behavioural
                 events

Uncontrolled installation of
      forest vegetation
 Increases the bed rugozity,
diminishes the stream speed
 and hinders the free flow of
       torrential waters

Descriptive elements of the behavioural
                  events

Covering of parts of works.
Leads to (partial or complete)
shut-down of transverse
hydrotechnical works.

Descriptive elements of the behavioural
                events

  Erosive degradation

  Reduce the rezistance and sustainability in time of the work

Research methodology

  The information recorded
in the field was introduced to a
Microsoft Access personalized
database in order to facilitate
the analysis of large amount of
data.

 The structure of the database comprised:
 • entities (ex. breakages) (encountered deficiencies/damages on
 hydrotechnical structures)
 • attributes (ex. proprieties of the breakages) ( the description and
 properties of damages/dysfunctionalities)
 • values (the quantification of the atribute) (the quantitative estimation of
 the entities)

Research results - correlations
    Considering the number of
affected parts of structures (NPLA),
the events rankings were:
• cracks (105), breakages (30),
damage through erosion (26)
• uncontrolled installation of
vegetation (140), clogging of the
apron (19), deepening of the valley
(16).

    Correlation analysis of the
relations between the number of
structures and the recorded events,
considered for both damage
categories and for individual
structures revealed a strong link

Research results - Cracks

Regarding the works, the most
affected were the dams

                                Regarding the component parts
                                the most affected parts were the
                                right wing, the body and left wing.

Research results – Breakages

Regarding the works, the most
affected were the dams

                                Regarding the component parts
                                the most affected parts were the
                                right apron terminal spur, left
                                guarding wall and the apron.

Research results – Erosive degradation

Regarding the works, the most affected were the dams and the sills

  Regarding the component parts the most affected parts were the
  apron and the spillway.

Research results – Deepening of the
 valley
The works who produced the deepening of the valley in the most of
the cases were the TRAVERSES

The results showed that the height influenced the siltation achievement
and this is why the deepening of the valley produced in this situation.

Conclusions

      An analysis of the events frequency to component parts of structures
indicated that the part with the highest events frequency was the apron,
affected in 71 cases by 8 events, the second ranked was the spillway area,
affected in 65 cases by 10 events, and the third was the left wing of a dam,
affected in 52 cases by 9 events.

      Correlation analysis of the relations between the number of structures
and the recorded events, considered for both damage categories and for
individual structures, revealed that there is a direct influence of the number
of structures on the amount of recorded events. The research also
indicated, on a statistical basis, the influence of various factors (e.g. the
structure height, the position of a structure in the hydrotechnical system) on
producing and manifestation of the damage events to hydrotechnical
structures.

Conclusions

          Knowledge on the functioning of hydrotechnical structures gives a
possibility to better identify the interactions between channel adjustments
to watershed environmental changes and human in-channel modifications.

         As the results shows, the height of the transverse hydrotechnical
structures directly influence the in-channel modifications.

          The above presented research shows a strong correlation between
the structures constructed in torrent valleys and the mode of valley adjustment,
which can be analyzed using statistical methods.

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