ACTION A.2: Topographic survey
The action is essential for the proper implementation of action C3 and to support a large number of other Actions. Detailed knowledge of the local topography and the hydrographic network is necessary to identify a suitable area for the water tank and the distribution channel that works by natural gravity following the terrain slope. Therefore, understanding where the surface water naturally accumulates or flows out it is of crucial importance.
A topographic relief, with particular emphasis on dimension and local hydrographic surveying, is carried out in the Palo Laziale forest (40 ha) and in SCI of Nestos Delta (GR1150010), focusing on the area occupied by the habitats 3170* and 91E0, to obtain high-resolution vector digital mapping topography. The topographic survey and the resulting map have absolute priority, and it is performed over the first year of the project.
As part of the preparatory work included in action A2, a further hydrological survey is carried out to measure the seasonal water supply of the Nestos River, and to determine water flow to temporary ponds, if any, and to the alluvial forest (91E0*). This further assessment in Nestos is necessary to design the subsequent hydraulic works properly. River levels necessary to inundate the 91E0* areas is also determined. If required for comparison and creation of time-series, historical data on river flow are provided by the competent Local Authority for Land Reclamation and the School of Geology of the Aristotle University of Thessaloniki. River discharge measurement is carried out using the conventional current meter method or natural tracer techniques. The former, the most used approach, it is based on the determination of the mean flow velocity and the cross-sectional area; the product of these two variables determines the flow rate of the stream. If this method of measurement is not applicable (for example, when the water depth is small and the flow rate high the irregular section and the strong turbulence decrease the precision of depth and speed measurement) an alternative technique is adopted. An example consists of introducing a tracer in the water and determining its dilution at a downstream point. The measurement with the dilution method can be useful where the current meter does not, and vice versa, so these techniques are complementary.
The data generated, along with the output of action A4, contribute to Actions C3 and C5.
Beneficiary responsible for implementation:
The action will be coordinated by Dep. DICEA, Sapienza University of Rome, relying on the following human resources:
- an Associate Professor for designing and supervising the survey and its digital map,
- a Topographic technician, with a specific contract for this work, who will be concerned with the topographic survey execution and its digital map implementation,
- a Hydrogeologist who will be concerned with the hydrological survey in Nestos.