Thanks to the accurate base maps, the flood map displays clearly and understandably which streets, buildings and cadastral units would remain under water in case of a possible flood. To find the building or street of interest a renewed address search is available, enabling to find the right place faster and easier than before. Modelling the rise in water level and displaying the relief is made possible due to accurate height information that the Land Board received from aero laser scanning in the years 2008–2010. According to Minister of the Environment Jaanus Tamkivi, publishing of the flood areas is extremely important since it enables each person to evaluate the personal risks based on that information and thus helps to take measures to protect one’s property and family. “For example, we can foresee problems with the high water level of Suur-Emajõgi in Tartu in the upcoming spring when such a map on the possible flood areas may prove highly useful,” Tamkivi noted. According to the Minister, the map of possible flood areas is especially valuable for its preciseness and usability with the topographic information of the Land Board. “Preparation of such a thematic map has only been possible thanks to large-scale investments made for purchasing the technology needed for gathering data, for example, a plane, an aero camera, a Lidar, and voluminous work that is far from being over when it comes to gathering relief data and increasing the quality of models,” Tamkivi said. In Pärnu, Haapsalu and Kuressaare, a rise in the water level has been presented in comparison with the Kronstadt zero, in Tartu, it is compared to a previously agreed zero point. The absolute height of the agreed zero in Tartu is 29.61 meters. The flood intervals, by towns, are as follows: Haapsalu 0.5–2.25 meters, Kuressaare 0.5–3.0 meters, Pärnu 1.5–3.5 meters, Tartu 1.5–4.0 meters (compared to the zero point). In deciding on the intervals, the Land Board considered publicly available data on the maximum water levels that have occurred. In Tartu, the minimum level was restricted by the high water level during the survey flight. The seawater level increase minimums start near the critical level. In Haapsalu and Pärnu, separate critical water level areas have been displayed – 0.8 meters in Haapsalu and 1.6 meters in Pärnu. The Land Board reminds everyone that this is a pilot project and the surface model on which the modelling was based has been prepared from automatically classified surface points. These points have five-meter steps, wherefore there may be some deviations in smaller artificial objects (for example, rivers with reinforced banks, ditches, bridges, etc.). Therefore, the Land Board is happy to receive any kind of feedback for further improvement of these models. In addition to the flood areas, the relief base map in the Map Server of the Land Board has been improved by a coloured shaded relief image instead of a grey one, coloured in accordance with the height and intensifying the ground relief, and a slope map for Saaremaa, displaying the ground slopes of 5–10% and over 10% (1% = 1m of rise for 100m). |
