**2.1.1 Description of study area**

The Čenkov plain is situated in the eastern part of the Danubian lowland, west apart from Štúrovo town. It is the fluvial plain of the Danube, which borders in the south on a 23 kilometre long river section between RK 1722 and 1745 and in the north in an arc stretching across the terrace platform, where on its boundary lies the Moča village, the Búč village, the Júrsky Chlm village, the Mužla village and the Obid village. The fluvial plain is from 2.5 km up to 6 km wide and has an overall area of 66 km2. Its surface is flat. The heights of the terrain vary from 106 up to 108 m a.s.l. The lowest-situated section under the terrace is on height level 105m a.s.l. and the highest situated section in the Čenkov wood is on the middle of the area 108 – 110m a.s.l. (Fig. 1 and 2).

Change of Groundwater Flow Characteristics After Construction of the

even in singular cases up to 1000 mm of precipitation.

**2.1.2.2 Hydrogeology and geology** 

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 57

indeed the warmest but also has the driest locality. In a series of long-term observations, the lowest annual precipitation totals vary in terms of 300 – 400 mm and minimum monthly precipitation totals in particular months do not even reach (except for July) 5 mm precipitation, whereupon significant dry periods are more often in summer half-year than in winter half-year. The lowest July precipitation totals do not drop under 10 mm. On the other hand wet (precipitation) periods are lasting here mostly from 18 to 20 days, and their appearance is relatively more rare than the appearance of dry periods and it occurs mostly in spring and autumn periods. The highest annual precipitation totals could reach 900 mm,

The Danube fluvial plain at observed river sections is built by sediment deposits of the Danube River, where their thickness varies irregularly between 5 - 12 m and the most frequent thicknesses are between 6 - 9 m. Gravel and sand dominate soil layers, which are in the highest part covered by alluvial loams. Gravel–sand fillings of the Danube fluvial plain's

Fig. 3. Hydrogeological profile 1-1 (400x exceeded). Comments: 1-young Pleistocene blown sands, 2-medium to smooth sands, 3-sandy gravel to rough sands with gravel, 4-downhill loamy sediments along upper terrace step, 5-dusty to loamy sands, eventually dusty – sandy loams, 9- marking of the tertiary base surface, 10-groundwater level on 29 Sept.1954, 11-the

It is possible to observe their partial subtilization in longitudinal profiles of gravel sand alluvia (Fig. 3 and 4) in the Danube direction, although the appearance of heavier gravel layers is possible in the whole profile. The left edge of the Danube's fluvial plain is lined by

highest groundwater level in years 1954 – 1956 (Duba, 1964)

bed in this section belong to Würm, and the cover of sandy loam is Holocene.

Fig. 1. Geographical situation of the Čenkov plain

Fig. 2. Water management map of the Čenkov plain
