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

Marina Babić Mladenović1, Milan Radovanović1 and Predrag Radosavljević2



1 Jaroslav Černi Institute for the Development of Water Resources, Jaroslava Černog 80, 11226 Pinosava, Belgrade, Serbia; This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 HPPs Djerdap Ltd., Trg Kralja Petra 1, 19320 Kladovo, Serbia




The Djerdap 1 and Djerdap 2 Hydro Power and Navigation System (HPNS), also known as the Iron Gate HPNS, are among the largest in Europe. Its purpose is to utilize the considerable hydropower potential and improve the conditions for navigation in the formerly very dangerous section of the Danube. During operation period HPNS has completely fulfilled its intended purpose. The average hydropower production per year is 13 TWh, and covers an important share of power demand in Serbia and Romania. Also, a permanent solution to the centuries-long problem of navigation along the Iron Gate stretch of the Danube River is provided. The Iron Gate HPNS generated considerable modifications of the natural river regime and raised a number of questions concerning water management decisions, such as: the reduced sediment transport capacity, followed by sediment deposition; the raising of the groundwater table, the endangerment of many communities and industrial, municipal and transportation facilities, as well as agricultural production in the riparian belt; the inadequacy of the existing flood control structures; the decrease of the ice transport capacity at the end of the backwater zone; etc. Over 40 years of system operation, most of the initially recognized water management problems were addressed by comprehensive protection works and measures. The environmental impacts and effects of the protection measures were investigated within the scope of a multidisciplinary and complex monitoring program, conducted by Jaroslav Cerni Institute. It is composed of 9 sub-programs, which thoroughly investigate all the possible river impoundment impacts and consequences for the social situation and the environment. This paper gives an overview of the activities and results of the Iron Gate HPNS monitoring, carried out by Jaroslav Cerni Institute on behalf of the Iron Gate Company, between 1974 and 2012.

Keywords: Danube, Iron Gate, environment, monitoring



Description of the Iron Gate HPNS

The Iron Gate Hydropower and Navigation System (HPNS) is one of the largest engineering projects ever undertaken in Europe, built to provide cost-effective and permanent utilization of available hydropower and to create adequate conditions for navigation along the Iron Gate stretch of the Danube. This system is built on part of the Danube River shared by Serbia and Romania (Fig. 1), and since 1963 jointly managed by two countries, through the Joint Commission and its bodies.


The idea of utilizing the hydropower potential and improving navigation along the stretch of the Danube shared by Serbia and Romania dates back many years. Its implementation began after World War II, when a declaration was signed by Yugoslavia and Romania in which the two countries agreed to jointly explore the possibility of constructing hydro-power plants within the Iron Gate stretch of the Danube (Bucharest, 1956), and another to form a Joint Project Management and Coordination Committee.

Extensive field and laboratory investigations were performed and studies were conducted during the 1957-1960 period, which resulted in the Extended Technical and Economic Memorandum (TEM) detailing technical, economic, financial, and legal conditions. In its conclusions, the TEM recommended that the shared stretch of the Danube should be used for the construction of two hydropower and navigation systems, at km 943 and km 862.8. It was proposed that the first system should be built at km 943, since it could utilize 80% of total potential and solve all navigation problems. The two governments approved the TEM in 1960, and agreed to continue study and project development activities.

The Agreement regarding Construction and Operation of the Iron Gate HPNS was signed in 1963, along with a convention and several other documents.

Final designs of Iron Gate 1 System structures were completed during the 1960-1963 period, and respective detail designs were prepared from 1964 to 1968. All design stages were supported by appropriate field and laboratory investigations and studies, commensurate with the size and importance of the system. Extensive hydrological, geological, geotechnical, morphological, hydraulic, sediment and other types of data were collected and appropriate geodetic inputs prepared.

Construction of the Iron Gate 1 dam began in September of 1964. In July of 1969, a navigation lock on the left (Romanian) bank was commissioned and in August of 1970, the first hydropower generators were placed on-line. The entire facility started operations on 16 May 1972.

An agreement between the Federal Executive Assembly of the Socialist Federal Republic of Yugoslavia and the Government of the Socialist Republic of Romania, addressing conditions for expansion of cooperation in the utilization of the hydropower potential of the Danube River (1977), approved the Iron Gate 2 construction project. Construction of this system began in December of 1977 and the hydro-power plants achieved their design capacities in 1986. Additional hydro-power plants, on the main stream and on the Gogos branch, were built in 1994 and 2000, respectively.

Main structures of HPNS

Main structures of the HPNS are built at km 943 (the IG1 Dam, Fig. 2) and km 862.8 of the Danube River (the IG2 Dam, Fig. 3), each including 2 navigation locks, an earthen non-overflow dam, 2 hydroelectric power plants, an overflow concrete gravity dam, and other facilities. The HPPs operate as run-of-river, and reservoirs provide daily and sometimes weekly flow regulation (only IG1, at low flows).

The IG1 dam (Fig. 2) is 1.280 m long. It consists of two symmetrical parts (Serbian and Romanian portion), which allows both countries to have an equal exploitation of the water resource for electricity production and for navigation purposes. Each part comprise a 34 m wide and 310 m long double step navigation lock, earthen non-overflow dam, hydro-electric power plant (with 6 turbines) and a part of overflow dam. The overflow concrete gravity dam in the middle of cross-section has 14 spillway bays (each 25 m wide, with double table-gates), enabling the evacuation of the flood with return period once in 10.000 years. Two 2.050 MW electric power-plants (with 21-35 m head, 8 700 m3/s installed discharge) generate an annual average of 11.5 billion kWh.

The IG 2 dam (Fig. 3) is located on the main course of the Danube River, and has a total width of 1.009 m. A 330 m wide HPP equipped with 16 units is located on the left bank, divided between Romania (8 units) and Serbia (8 units), followed by a spillway (all within Serbia territory) of 196 m and 14 gates (21 m wide, regulated by radial sluice gates), an earthfill dam and a navigation lock 34 m wide. Also, the additional HPPs were built, Serbian on the right bank, and Romanian some 12 kilometres upstream, at the secondary dam on Gogosu branch. This dam is 509 m long, with a 196 m wide spillway with 7 gates (21 m wide, controlled by radial sluice gates); the central portion of the structure is an earthfill dam, while towards the right bank is a 70 m wide HPP.


Fig. 1: Iron Gate HPNS in the Danube River Basin


Fig. 2: Iron Gate 1 (IG1) dam


Fig. 3: Iron Gate 2 (IG2) dam