Mapping of mountainous terrain for the construction of Hydroelectric power plant

In recent years, there has been a significant increase in the number of inhabitants and in the volume of tourism in northwestern Georgia close to the cities of the Caucasus and the Black Sea. Quite naturally, the need has arisen for increased supply of electricity, and therefore it was decided that a Hydro-Electrical power plant should be established in the region. The plant’s location, the required dams, the water channels and strength of the water’s flow are critical factors influencing the effectiveness of the electric power production.

The planning of the drainage of the region rivers and the channeling of the water through the use of precise topographical mapping has supplied answers to the following questions:

What will be the power plant’s precise location? Where should the dams and the drainage canals be located? What is the optimal waterfall height and location needed for the maximization of electricity generation? What is the precise velocity of the water flow? What can strengthen/prevent the water flow?

A detailed aerial mapping of the terrain of the basin, approximately 450 square kilometers, has enabled the determination of the optimal location of the power plant and the location of the network of dams and water channeling needed for the creation of powerful, effective energy generation.

Green energy is in the house

In order to increase the supply of electricity to the region, it has been decided to produce electricity using green methods with the utilization of the immense natural resources that the country has been blessed with. The proposed plant’s location is a basin through which the Rioni River passes – an ideal location for the construction of a system of dams and establishment a Hydroelectric power plant, because of the significant height differences in the water drainage.

After an understanding was reached of the natural conditions, the region and the demands, three desired products were determined:

  1. LIDAR mapping – Airborne laser system that creates a precise topographical mapping of the area by using special technique to separate between the relief and land cover.
  2. A high-resolution orthophoto.
  3. Mapping of man-made elements (such as structures, bridges, power lines, etc.)

DTM layer of the area, from the LIDAR system

In order to produce these products, two different kinds of flights are needed:

  1. A Lidar survey flight to achieve concentrated laser hits per m2 in a very steep and mountainous region, using the LIDAR system.
  2. An aerial photography flight mission to acquire geo referenced vertical images of the area.

A complex flight mission requires precise planning, advanced systems and experienced personnel

Due to the complexity of the project because of the complicated topography and very dense forested area, It was not possible to use a drone to perform the flight mission and only a designated aircraft for geo-surveys with unique LIDAR sensors could perform the mission properly. Moreover, the project took place near the border areas of Georgia, which required special attention in order to carry out the task properly, in time and with maximum safety for the crew.

The region is very mountainous and that fact will require flights at different altitudes, including flying at a very low altitudes in valleys between the mountains in order to achieve the required precision and resolution for this project (between 5 and 10 laser points per m2).

Ofek’s plain need to fly very carefully, in a complex area

LIDAR from the air and GPS from the ground = a winning combination for precision

The most critical goal in this type of projects is obtaining high level precision in order to determine the location of each significant component of the plant – the power generators, the dams and the drainage canals. It is important to see the whole, precise picture. An undesirable scenario that could take place (and has taken place in the past) due to imprecise planning at this stage would be the following: everything would operate smoothly but, because of the overly powerful confrontation of sediment with certain points in the dam, an erosion of the structure would begin and in the not too distant future the structure could collapse.

A 3D model of the Area

Therefore, an Ofek field team operated two GPS systems that were located at a distance of up to 50 km radius from the flying aircraft. These positions sent out precise differential GPS data that was entered, by means of a special computer software program, into our products. Thus, a very precise calculation of the location of all the LIDAR screenings was achieved.

The result: Resolutions that were much higher than the anticipated resolutions

Ultimately, the client received the LIDAR products at a level of density and resolution that were much more accurate to what was requested. Here are the four types of products that have helped the client to understand topography of the designated region for the power plant’s construction:

  1. Orthophoto imagery at two different resolutions, 5 cm and 20 cm, in specific regions.
  2. DTM grid of the topography of the land surface which enables to calculate the slopes and therefore the water currents.
  3. DSM grid that provides the height model of the land cover, providing a height value to each point of the land cover surface.
  4. A photogrammetric mapping at a scale of 1:500 of the land’s surface, structures, walls, bridges, fences and all other man made elements. this product is compatible to Autocad and GIS mapping layers.

Orthophoto of the area

In the end…

The mapping materials were presented to the client and were authorized for use. The precise relief and land cover that were supplied enabled the client to plan where to locate each component to be constructed: the power plant, the dams and the drainage canals. In the very near future, the detailed planning stage of the hydroelectric power plant will begin and the client can rest assured with regard to the calculation of the amounts of water flow and the stability of the structures for many years to come.