Monitoring of the Iron Gate Hydropower and Navigation System on the Danube River - page 3

Protection of riparian lands

Riparian lands of the IG1 reservoir have different characteristics, which determine the magnitude of reservoir impacts and methods of protection. In the 80 km long reservoir part in the Iron Gate Gorge, the backwater impends only some localities on both sides of the Danube River (some settlements, infrastructure and high riverbanks). The upstream part of the reservoir extends through Serbian lowlands, and impacts the river, groundwater and inland water regimes.

Under the influence of the IG1 HPP backwater, the natural conditions in large and lowland riverine areas in Serbia were permanently changed. If the protection measures had not been undertaken, the backwater would have caused temporary or permanent flooding of some areas, raised the groundwater table (endangering many communities and industrial, municipal and transportation facilities), altered the ecosystem, imperiled the stability of flood defenses and high riverbanks, etc.

The backwater of IG2 HPP also influences the plain coastal zone, where the groundwater regime has changed. However, the disturbance of the natural regime is not as significant as in the upstream reservoir.

The problem of riverside and environmental protection was very carefully resolved, through the implementation of optimal and complex solutions. The construction of a system for the protection of riverine areas started before the construction of the IG1 and IG2 dams, and it is still on-going. Its objective is to ensure the conditions for timely prevention of IG1 and IG2 reservoir impacts, which must last (with certain modifications) throughout the life of the HPNS and beyond.

Major impacts of the IG1 reservoir were timely revealed and adequately alleviated by comprehensive protection works and measures: 400 km of new or reconstructed levees, 50 km of new revetments, drainage systems covering 1 350 km2 with 900 km long channels, 1 200 artesian drainage wells, 60 pumping stations, local protection of communities and industrial zones, etc.

Measures implemented along the IG2 reservoir are less significant than upstream, and encompassed dislocation and/or protection of existing settlements and facilities.

The operation of the HPNS also stimulated economical, demographic, social and cultural development in their surroundings. In this domain many tasks were performed (constructed new roads and ports on the Danube River, relocated endangered settlements and industrial and other facilities, relocated or protected ancient monuments etc.).

 

Monitoring Program

Regular monitoring and the study of environmental impacts started after the filling of IG 1 reservoir, in order to ensure prompt remedial measures whenever necessary and to obtain data for analyses of possible adjustments to the IG1 HPP operating mode. It was expanded in 1978, when experts of the Jaroslav Cerni Institute developed a multidisciplinary and very complex Program for the monitoring, measurement and analyses of Iron Gate 1 reservoir impacts. It comprised 9 specific sub-programs for the monitoring of:

  1. river flow and backwater levels;
  2. groundwater levels and drainage systems operation;
  3. sediment regime and deposition;
  4. ice regime;
  5. agricultural land preservation measures;
  6. forests and wetlands;
  7. flood control structures;
  8. quality of water and sediment; and
  9. riverbank and landslide stability.

In 1985, a very similar monitoring program was instituted for the IG2 reservoir.

For each program, the types and scope of investigations were initially defined, but in the course of their implementation many adjustments and modifications were made. The monitoring is still ongoing.

A short description of the 9 monitoring programs, the most important data obtained and some recommendations are presented below.