## 2 Hydrographic Survey Planning
### Planning the Hydrographic Survey to Establish the Territorial Sea Baseline  
Territorial sea baseline measurements are performed in shallow coastal waters [5]. In Poland, the line is situated between several dozen and 1-2 m below the current water level, and its position depends on the day (water level fluctuations) and place along the coast (the seafloor shape varies from one waterbody to another). Therefore, several representative waterbodies were selected, to perform the baseline measurements (Table 2).  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Name of Waterbody** & **Features** & **Photograph** \\ \hline Waterbody No. 1: Open sea & A typical coastline (straight line sandy section), reinforced with tetrapods and concrete wharks. The length of the waterbody along the coastline is about 450 m. \\ \hline Waterbody No. 2: River mouth & A waterbody of great dynamics of hydomorphological features. It is a natural area (with no hydrotechnical structures). The length of the waterbody along the coastline is about 250 m. \\ Waterbody No. 3: Exit from a large port & A waterbody with a large number of hydrotechnical structures. The length of the waterbody along the coastline is about 250 m. \\ \hline Waterbody No. 3: Exit from a large port & A waterbody with a large number of hydrotechnical structures. The length of the waterbody along the coastline is about 250 m. \\ \hline \hline \end{tabular}
\end{table}
Table 2: Representative waterbodies where measurements of the territorial sea baseline were conducted. Own study based on [18].  
The geographic locations of the representative waterbodies (analysed above in Table 2) are re shown in Figure 1.  
The sounding profile arrangement differs depending on where the baseline measurements are performed. Figures 2-4 show the measurement profiles for three representative waterbodies, designed in accordance with the general principles of planning hydrographic survey. They were created using the free Google Earth Pro platform. The main sounding profiles were established perpendicularly to the coastline and it was assumed that the distances between those profiles are 5-10 m. Moreover, in order to verify the measurements, control profiles were designed perpendicularly to the direction of the main profiles while observing the rules laid down in [9]. Figure 2 shows an example of sounding plan in waterbody No. 1, adjacent to the municipal beach.  
Figure 1: The geographic locations of the representative waterbodies.  
Figure 2: The system of main and control profiles in the territorial sea baseline determination for waterbody No. 1.  
The systems of sounding profiles for waterbodies No. 2 and 3 (Figures 3 and 4) were planned in the same way as for waterbody No. 1, described above.  
At the hydrographic survey stage, it is important to have software for planning (deploying) sounding lines and visualisation (if needed) of the position of a vessel on a map. Most programs of this type are able to design sounding profiles (directions and distances between them) based on a specific waterbody, usually on the basis of an orthophotomap from the Google Maps service (Figure 5a) [19]. Some of them also have the ability to monitor a vessel position in real time. The most popular programs used to plan navigation (inland and maritime) include HYPACK, OpenCPN, QINSy (Figure 5b) and Transas iSailor.  
Figure 4: The system of main and control profiles in the territorial sea baseline determination for waterbody No. 3.  
Figure 3: The system of main and control profiles in the territorial sea baseline determination for waterbody No. 2.