Monitoring of the Iron Gate Hydropower and Navigation System on the Danube River - page 4

Activities and Results of Monitoring

(I) Monitoring of river flow and backwater levels

This is a basic program, comprising field measurements of water levels and river flow at numerous stations (Fig. 7), annual and periodic reports with the comparison of measured and designed backwater levels.

Its results are used for the analyses of temporal and spatial variation of water levels, as well as for the design or verification of protection systems within the IG1 and IG2 reservoirs.

 

Fig7
Fig. 7: Layout of stations for surface water monitoring

(II) Monitoring of groundwater levels and drainage system operation

Before the creation of the HPNS, the problems of high groundwater levels and excess ground moisture were present in Danube riversides, and they were solved by protection systems and measures. Due to the HPNS backwater, the impact significantly increased in some areas, and the construction and adequate functioning of protection systems became the precondition for any use of land in the riverine areas.

In accordance with the defined concept of protection and regulation of the low riparian land, and depending on the specific conditions prevailing in the region, appropriate technical measures were selected and implemented.

In this regard, the following two methods of protection may be differentiated, depending on the selected criteria of the depth to the groundwater level:

(A) - Protection of agricultural regions (depth to the groundwater level of 0.8-1 m from the terrain surface was selected as the protection criterion) is achieved by means of measures presented on Fig. 8 and 9:

(a) a network of open drainage channels in combination with old branches of the Danube and parts of other waterways, including pumping stations;

(b) a network of open channels in combination with artesian drainage wells, including pumping stations.

(B) - Protection of populated areas (selected criteria of the depth to the groundwater level are 3 m for cities and 2 m for small communities) is achieved by operating drainage wells with submersible pumps, and drainage collectors (Fig. 10).

Monitoring program No (II) is the basis for understanding the influence of the reservoir on the groundwater regime, and includes monitoring of: Groundwater levels on piezometers and wells on all the areas under the influence of the Iron Gate HPNS. The groundwater levels are presently measured regularly on 830 piezometers (Fig. 11); Water levels on the network of drainage channels; Performance of pumping stations (water levels, pumping time line, water quantities); Operation of all elements of drainage systems (regime and effects of drainage wells, galleries, channels, etc.); Modifications of groundwater quality on drainage wells and piezometers.

 

Fig8
Fig. 8: Measures for agricultural land protection

 

Fig9
Fig. 9: Drainage channels and piezometers at Dubovac-Kovin area at the right bank of the IG1 reservoir