**5. Analyses and comparison of representative groundwater regime of the territory before, and after construction of protective measures**

The processing of the observed data and creation of numerical models enables the clarification of the laws of the groundwater regime, in particular to determine its fundamental characteristics, which are: the level heights and main directions of the groundwater flow, depth of the groundwater level under the terrain, the fluctuation of the underground level, the lines of development of changes of the groundwater level in time, volumetric budget and hydrogeological profiles.

*The height of levels and main directions of groundwater flow* shall be determined using the isolines of the piezometric heights of groundwater level (piezometric contours; for a free level ground water table contours) as the basic document. Firstly they are constructed for the characteristic conditions of the factors that may affect the groundwater regime, according to the knowledge of the hydrogeological and geomorphological conditions of the territory and the preliminary assessment of the observed data. They are the extreme cases of the occurrence of the meteorological factors, such as the periods after extraordinary heavy

Change of Groundwater Flow Characteristics After Construction of the

**4**

**4**

**4**

**4**

**Plan view**

**3**

**Cross section 3-3**

**Cross section 3-3**

**Plan view**

**3**

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 67

Contour levels: min. 101.34 m a.s.l., max. 107.94 m a.s.l. Flowlines: the groundwater flows from the aquifer from the Búčšsky pond to the Danube River via the "window" next to Kravany. Smaller amount of groundwater flows to the Danube River via the "Window" at Čenkov. Velocity vectors: the maximal speeds of the groundwater flow are in the Eastern zone of the water source of Kravany towards the wells. Maximum value of horizontal pore

velocity is 1.23E-03 m.s-1 and maximum vertical pore velocity is 8E-08 m.s-1 (Fig. 10).

**Danube**

Fig. 11. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer before the construction of protective measures – average water stage of the Danube

Contour levels: min. 103.32 m a.s.l., max. 107.91 m a.s.l. Flowlines: the Western half of the territory of interest is drained by the Danube River. The water source of Kravany drains the circular zone up to the Kravany channel. The aquifer is supplied from the settlement of Čenkov up to the pumping station Obid by the Danube River. The interior is drained by and water is conducted away by the drainage channels, in particular the Obid and Mužľa ones. Velocity vectors: the maximal speeds of flow are around the water source of Kravany in second model layer and somehow lower ones are in the Eastern part of the territory of interest in the section of Obid - Štúrovo in third model layer. Maximum value of horizontal pore velocity is 4.32E-04 m.s-1 and maximum vertical pore velocity is 4.21E-09 m.s-1 (Fig. 11).

Fig. 12. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer

after the construction of protective measures – average water stage of the Danube

**Cross section 4-4**

**Cross section 4-4**

**3**

rainfall or after prolonged rain-free periods. In addition, they are construed also for the periods of the occurrence of the extreme and average conditions of the groundwater for the observation period. Such processing produces the basic data on the conditions of supply and drainage of the groundwater within the territory.

Fig. 9. Steady state head distribution (black lines, m a.s.l. ), flowlines (blue lines in the third model layer, purple lines in the second model layer) and velocity vectors(green, m.s-1 ) in the 3rd model layer before the construction of protective measures – minimum water stage of the Danube

Contour levels: min. 101.42 m a.s.l., max. 104.43 m a.s.l. Flowlines: the direction of the flow of groundwater is from the aquifer to the Danube River lengthwise. Velocity vectors: maximal speeds of the groundwater flow are at the Vojnice brook beyond the effluent from the Búčsky pond in second model layer and somehow smaller speeds are in the Eastern part of the territory of interest at Štúrovo, at Čenkov and at the proximity of the Modranský brook in the third model layer. Maximum value of horizontal pore velocity is 5.11E-04 m.s-1 and maximum vertical pore velocity is 3.89E-07 m.s-1 (Fig. 9).

Fig. 10. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer after the construction of protective measures – minimum water stage of the Danube

rainfall or after prolonged rain-free periods. In addition, they are construed also for the periods of the occurrence of the extreme and average conditions of the groundwater for the observation period. Such processing produces the basic data on the conditions of supply

**Cross section 4-4**

**Cross section 4-4**

**3**

**3 3**

**Danube**

Fig. 9. Steady state head distribution (black lines, m a.s.l. ), flowlines (blue lines in the third model layer, purple lines in the second model layer) and velocity vectors(green, m.s-1 ) in the 3rd model layer before the construction of protective measures – minimum water stage of the

Contour levels: min. 101.42 m a.s.l., max. 104.43 m a.s.l. Flowlines: the direction of the flow of groundwater is from the aquifer to the Danube River lengthwise. Velocity vectors: maximal speeds of the groundwater flow are at the Vojnice brook beyond the effluent from the Búčsky pond in second model layer and somehow smaller speeds are in the Eastern part of the territory of interest at Štúrovo, at Čenkov and at the proximity of the Modranský brook in the third model layer. Maximum value of horizontal pore velocity is 5.11E-04 m.s-1

**Danube**

Fig. 10. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer after the construction of protective measures – minimum water stage of the Danube

and drainage of the groundwater within the territory.

**4**

**4**

and maximum vertical pore velocity is 3.89E-07 m.s-1 (Fig. 9).

**4**

**4**

**Cross section 3-3**

Danube

**Plan view**

**3**

**Cross section 3-3**

**Plan view**

Contour levels: min. 101.34 m a.s.l., max. 107.94 m a.s.l. Flowlines: the groundwater flows from the aquifer from the Búčšsky pond to the Danube River via the "window" next to Kravany. Smaller amount of groundwater flows to the Danube River via the "Window" at Čenkov. Velocity vectors: the maximal speeds of the groundwater flow are in the Eastern zone of the water source of Kravany towards the wells. Maximum value of horizontal pore velocity is 1.23E-03 m.s-1 and maximum vertical pore velocity is 8E-08 m.s-1 (Fig. 10).

Fig. 11. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer before the construction of protective measures – average water stage of the Danube

Contour levels: min. 103.32 m a.s.l., max. 107.91 m a.s.l. Flowlines: the Western half of the territory of interest is drained by the Danube River. The water source of Kravany drains the circular zone up to the Kravany channel. The aquifer is supplied from the settlement of Čenkov up to the pumping station Obid by the Danube River. The interior is drained by and water is conducted away by the drainage channels, in particular the Obid and Mužľa ones. Velocity vectors: the maximal speeds of flow are around the water source of Kravany in second model layer and somehow lower ones are in the Eastern part of the territory of interest in the section of Obid - Štúrovo in third model layer. Maximum value of horizontal pore velocity is 4.32E-04 m.s-1 and maximum vertical pore velocity is 4.21E-09 m.s-1 (Fig. 11).

Fig. 12. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer after the construction of protective measures – average water stage of the Danube

Change of Groundwater Flow Characteristics After Construction of the

**4**

the Danube before the construction of protective measures (m)

the Danube after the construction of protective measures (m)

**4**

or free level of groundwater.

**Cross section 3-3**

**Plan view**

**3**

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 69

composition of the surface deposits. When comparing the depths with the thickness of layer of the surface deposits, in the case of their little permeability they enable to assess the groundwater flow regime, thus to earmark the areas or periods with the occurrence of tense

Fig. 14. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer after the construction of protective measures – maximum water stage of the Danube

Fig. 15. Depth of groundwater level below the ground surface at minimum water stage of

Fig. 16. Depth of groundwater level below the ground surface at minimum water stage of

**Cross section 4-4**

**3**

Contour levels: min. 102.79 m a.s.l., max. 107.95 m a.s.l. Flowlines: the aquifer drains the Danube River via the window at Kravany approximately from the territory of the intravillain of the village of Kravany. The aquifer drains significantly more via second window at Čenkov, where it takes out the groundwater from the water reservoir at the village Búč. The interior is drained by and water is conducted away by the system of drainage channels, in particular the Obid channel. Velocity vectors: the highest speeds of flow re in second model layer around the water source of Kravany. Maximum value of horizontal pore velocity is 1.13E-03 m.s-1 and maximum vertical pore velocity is 1.06E-07 m.s-1 (Fig. 12).

Contour levels: min. 104.00 m a.s.l., max. 109.53 m a.s.l. Flowlines: the Danube River fills the aquifer lengthwise. The groundwater is drained in the interior by and conducted away by the system of drainage channels. Velocity vectors: the maximal speeds of flow are between the Kravany channel and the Danube River in second model layer. Maximum value of horizontal pore velocity is 9.42E-03 m.s-1 and maximum vertical pore velocity is 5.82E-07 m.s-1 (Fig. 13).

Contour levels: min. 102.50 m a.s.l., max. 109.53 m a.s.l. Flowlines: The Danube River supplies the entire aquifer via both windows. The groundwater is drained in the interior by and conducted towards the pumping stations by all drainage channels. Velocity vectors: the maximal speeds of flow are in the area between the Kravany channel and the Danube River in second model layer. The highest speeds of flow of the groundwater in third model layer are in the intravillain of the village of Kravany and at Čenkovo. Maximum value of horizontal pore velocity is 7.67E-04 m.s-1 and maximum vertical pore velocity is 6.70E-08 m.s-1 (Fig. 14).

*Depth of the groundwater level under the terrain* is conditioned by its height and morphology of the area. The significance of the processing of depth at analogous water stages as the isolines of piezometric heights lies in the fact they enable to assess the possibility of supply of groundwater from rainfall or their drainage by evapotranspiration in dependence upon the

Fig. 13. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer before the construction of protective measures – maximum water stage of the Danube

Contour levels: min. 102.79 m a.s.l., max. 107.95 m a.s.l. Flowlines: the aquifer drains the Danube River via the window at Kravany approximately from the territory of the intravillain of the village of Kravany. The aquifer drains significantly more via second window at Čenkov, where it takes out the groundwater from the water reservoir at the village Búč. The interior is drained by and water is conducted away by the system of drainage channels, in particular the Obid channel. Velocity vectors: the highest speeds of flow re in second model layer around the water source of Kravany. Maximum value of horizontal pore velocity is 1.13E-03 m.s-1 and maximum vertical pore velocity is 1.06E-07

Contour levels: min. 104.00 m a.s.l., max. 109.53 m a.s.l. Flowlines: the Danube River fills the aquifer lengthwise. The groundwater is drained in the interior by and conducted away by the system of drainage channels. Velocity vectors: the maximal speeds of flow are between the Kravany channel and the Danube River in second model layer. Maximum value of horizontal pore velocity is 9.42E-03 m.s-1 and maximum vertical pore velocity is 5.82E-07

Contour levels: min. 102.50 m a.s.l., max. 109.53 m a.s.l. Flowlines: The Danube River supplies the entire aquifer via both windows. The groundwater is drained in the interior by and conducted towards the pumping stations by all drainage channels. Velocity vectors: the maximal speeds of flow are in the area between the Kravany channel and the Danube River in second model layer. The highest speeds of flow of the groundwater in third model layer are in the intravillain of the village of Kravany and at Čenkovo. Maximum value of horizontal pore velocity is 7.67E-04 m.s-1 and maximum vertical pore velocity is 6.70E-08

*Depth of the groundwater level under the terrain* is conditioned by its height and morphology of the area. The significance of the processing of depth at analogous water stages as the isolines of piezometric heights lies in the fact they enable to assess the possibility of supply of groundwater from rainfall or their drainage by evapotranspiration in dependence upon the

**Danube**

Fig. 13. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer before the construction of protective measures – maximum water stage of the Danube

**Cross section 4-4**

**3**

m.s-1 (Fig. 12).

m.s-1 (Fig. 13).

m.s-1 (Fig. 14).

**3**

**Cross section 3-3**

**Plan view <sup>4</sup>**

**4**

composition of the surface deposits. When comparing the depths with the thickness of layer of the surface deposits, in the case of their little permeability they enable to assess the groundwater flow regime, thus to earmark the areas or periods with the occurrence of tense or free level of groundwater.

Fig. 14. Steady state head distribution, flowlines and velocity vectors in the 3rd model layer after the construction of protective measures – maximum water stage of the Danube

Fig. 15. Depth of groundwater level below the ground surface at minimum water stage of the Danube before the construction of protective measures (m)

Fig. 16. Depth of groundwater level below the ground surface at minimum water stage of the Danube after the construction of protective measures (m)

Change of Groundwater Flow Characteristics After Construction of the

the Danube before the construction of protective measures (m)

the Danube after the construction of protective measures (m)

construction of protective measures (m)

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 71

Fig. 19. Depth of groundwater level below the ground surface at maximum water stage of

Fig. 20. Depth of groundwater level below the ground surface at maximum water stage of

The maximal groundwater level depth is up to 5.76 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The piezometric pressure head reaches the value up to 0.5 m above the terrain surface in the intravillain of the village of Kravany (Fig. 20).

*Fluctuation of groundwater levels,* plotted as the difference between the extreme heights or depths under the terrain for the observation period, determines the maximal amplitude of the fluctuation on the particular observation spot that may be depicted using the lines with the same fluctuation. From the isolines, it is then possible to determine, when comparing with the values of the fluctuation in the surface recipients and the values of rainfall, as well

Fig. 21. The difference between the maximum and minimum groundwater level before the

The maximal groundwater level depth is up to 8.5 m under the terrain surface and it occurs at the Western border of the territory of interest between the village of Moča and the Modriansky brook. The minimal depth is 2.00 m and it is located at the drainage channels, in particular the Obid, the Krížny and Mužliansky brooks (Fig. 15).

The maximal groundwater level depth is up to 8.0 m under the terrain surface and it occurs in the route of the window in the underground non-permeable wall at Čenkov. The minimal depth is 0.00 m and it is located at the boundary of the territory to the East of the village of Mužla (Fig. 16).

The maximal groundwater level depth is up to 6.30 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The minimal depth is 0.60 m and it is located to the South next to the intravillain of the village of Mužla (Fig. 17).

Fig. 18. Depth of groundwater level below the ground surface at average water stage of the Danube after the construction of protective measures (m)

The maximal groundwater level depth is up to 6.86 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The minimal depth is 0.34 m and it is located at the beginning of the Kravany channel (Fig. 18).

The maximal depth of the groundwater level is 4.37 m under the terrain surface and it occurs at the Western border of the territory of interest between the village of Moča and the Modriansky brook. The piezometric pressure head reaches the value of 3.29 m above the terrain surface in the proximity of the pumping station Obid (Fig. 19).

The maximal groundwater level depth is up to 8.5 m under the terrain surface and it occurs at the Western border of the territory of interest between the village of Moča and the Modriansky brook. The minimal depth is 2.00 m and it is located at the drainage channels,

The maximal groundwater level depth is up to 8.0 m under the terrain surface and it occurs in the route of the window in the underground non-permeable wall at Čenkov. The minimal depth is 0.00 m and it is located at the boundary of the territory to the East of the village of

Fig. 17. Depth of groundwater level below the ground surface at average water stage of the

The maximal groundwater level depth is up to 6.30 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The minimal depth is 0.60 m and it is located to

Fig. 18. Depth of groundwater level below the ground surface at average water stage of the

The maximal groundwater level depth is up to 6.86 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The minimal depth is 0.34 m and it is located at

The maximal depth of the groundwater level is 4.37 m under the terrain surface and it occurs at the Western border of the territory of interest between the village of Moča and the Modriansky brook. The piezometric pressure head reaches the value of 3.29 m above the

in particular the Obid, the Krížny and Mužliansky brooks (Fig. 15).

Danube before the construction of protective measures (m)

Danube after the construction of protective measures (m)

terrain surface in the proximity of the pumping station Obid (Fig. 19).

the beginning of the Kravany channel (Fig. 18).

the South next to the intravillain of the village of Mužla (Fig. 17).

Mužla (Fig. 16).

Fig. 19. Depth of groundwater level below the ground surface at maximum water stage of the Danube before the construction of protective measures (m)

Fig. 20. Depth of groundwater level below the ground surface at maximum water stage of the Danube after the construction of protective measures (m)

The maximal groundwater level depth is up to 5.76 m under the terrain surface and it occurs in the Southern part of the Čenkov forest. The piezometric pressure head reaches the value up to 0.5 m above the terrain surface in the intravillain of the village of Kravany (Fig. 20).

*Fluctuation of groundwater levels,* plotted as the difference between the extreme heights or depths under the terrain for the observation period, determines the maximal amplitude of the fluctuation on the particular observation spot that may be depicted using the lines with the same fluctuation. From the isolines, it is then possible to determine, when comparing with the values of the fluctuation in the surface recipients and the values of rainfall, as well

Fig. 21. The difference between the maximum and minimum groundwater level before the construction of protective measures (m)

Change of Groundwater Flow Characteristics After Construction of the

groundwater in the case of shallow saturated collectors.

M.G. & Harbaugh A.W.,1988).

protective measures.

0.00E+00

the protective measures.

5.00E-02

1.00E-01

1.50E-01

**Groundwater flow from the aquifer into the** 

**Danube (m3.s-1)**

2.00E-01

2.50E-01

y = 4E+66e-1.5127x R2 = 0.9314

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 73

outflow, surface outflow to the rivers or reservoirs and other surface recipients, underground outflow into other catchment areas or hydrogeological units, rainfall infiltrating on the particular territory, the overall evapotranspiration reducing the stock of

*Volumetric budget.* A summary of all inflows and outflows to a region is generally called a water budget. In this case, the water budget is termed a volumetric budget because it deals with volumes of water and volumetric flow rates; thus strictly speaking it is not a mass balance. A water budget provides an indication of overall acceptability of the solution. The system of equations solved by the model actually consists of a flow continuity statement for each model cell. The water budget is calculated independently of the equation solution process, and in this sense may provide independent evidence of a valid solution (McDonald,

The displayed exponential dependence on Fig. 24 from the results of calculations of volume budget show that the approximate limit of the change in the groundwater outflow from the aquifers to the Danube River is an average water stage of the Danube of 104.5 m a.s.l. Water stages of the Danube River exceeding the limit cause low, approximately the same outflow of groundwater from the aquifers to the Danube River both before and after the construction of the protective measures. At water stages of the Danube River below the specified limit the differences in the outflow are increased and at the minimal water stage of the Danube River of 102.5 m a.s.l. the groundwater outflow (m3.s-1) after the completion of the protective measures is approximately five times lower than it was before the completion of the

> 102 103 104 105 106 107 108 109 110 **Average water level of Danube in the "windows" (m a.s.l.)**

Similarly, for the flow of water from the Danube River to the aquifer the relation may be expressed using the exponential dependence (Fig. 25). At the minimal water stage of the Danube River the dependence is almost the same before and after the completion of the protective measures. The differences in the flows are exponentially increased between the average and maximal water stage of the Danube River and at the high water stage of the Danube River after the completion of the protective measures the flow of water from the Danube River to the aquifer is more than fivefold lower than it was before the completion of

Fig. 24. Groundwater flow from the aquifer into the Danube River (m3.s-1)

y = 5E+31e-0.743x R2 = 0.8406

Before protective measures After protective measures

as the meteorological data characterizing the total evapotranspiration, also the regime specificities of the particular territorial units.

The difference between the maximum and minimum groundwater level before the construction of protective measures reaches the maximal values up to 6.48 m on the narrow strip alongside the entire non-permeable underground wall. To the North towards the interior, the differences are diminished and they reach the minimal values down to 0.00 m on the Northern border of the territory of the interest (Fig. 21).

Fig. 22. The difference between the maximum and minimum groundwater level after the construction of protective measures (m)

The difference between the maximum and minimum groundwater level after the construction of protective measures reaches the maximal values up to 6.6 m in the window at Kravany and negative values down to 2.38 m on the Northern border of the territory (Fig. 22).

Fig. 23. The difference of groundwater level at the maximum water stage of the Danube (this means groundwater level after the construction of protective measures minus before the construction) (m)

*Time slope lines of the changes of the groundwater levels,* created for a prolonged observation period from the entire observation network (the SHMÚ, or other boreholes on purpose), together with the hydrogeological profiles form the fundamental preconditions for the demarcation of the territorial units and areas with the prevailing impact of the individual influences, inducing the supply or drainage of groundwater. These impacts are: underground inflow from the rivers or any other surface water recipients, underground inflow from the neighbouring hydrological or hydrogeological units, surface inflow and

as the meteorological data characterizing the total evapotranspiration, also the regime

The difference between the maximum and minimum groundwater level before the construction of protective measures reaches the maximal values up to 6.48 m on the narrow strip alongside the entire non-permeable underground wall. To the North towards the interior, the differences are diminished and they reach the minimal values down to 0.00 m

Fig. 22. The difference between the maximum and minimum groundwater level after the

The difference between the maximum and minimum groundwater level after the construction of protective measures reaches the maximal values up to 6.6 m in the window at Kravany and negative values down to 2.38 m on the Northern border of the territory

Fig. 23. The difference of groundwater level at the maximum water stage of the Danube (this means groundwater level after the construction of protective measures minus before the

*Time slope lines of the changes of the groundwater levels,* created for a prolonged observation period from the entire observation network (the SHMÚ, or other boreholes on purpose), together with the hydrogeological profiles form the fundamental preconditions for the demarcation of the territorial units and areas with the prevailing impact of the individual influences, inducing the supply or drainage of groundwater. These impacts are: underground inflow from the rivers or any other surface water recipients, underground inflow from the neighbouring hydrological or hydrogeological units, surface inflow and

specificities of the particular territorial units.

construction of protective measures (m)

(Fig. 22).

construction) (m)

on the Northern border of the territory of the interest (Fig. 21).

outflow, surface outflow to the rivers or reservoirs and other surface recipients, underground outflow into other catchment areas or hydrogeological units, rainfall infiltrating on the particular territory, the overall evapotranspiration reducing the stock of groundwater in the case of shallow saturated collectors.

*Volumetric budget.* A summary of all inflows and outflows to a region is generally called a water budget. In this case, the water budget is termed a volumetric budget because it deals with volumes of water and volumetric flow rates; thus strictly speaking it is not a mass balance. A water budget provides an indication of overall acceptability of the solution. The system of equations solved by the model actually consists of a flow continuity statement for each model cell. The water budget is calculated independently of the equation solution process, and in this sense may provide independent evidence of a valid solution (McDonald, M.G. & Harbaugh A.W.,1988).

The displayed exponential dependence on Fig. 24 from the results of calculations of volume budget show that the approximate limit of the change in the groundwater outflow from the aquifers to the Danube River is an average water stage of the Danube of 104.5 m a.s.l. Water stages of the Danube River exceeding the limit cause low, approximately the same outflow of groundwater from the aquifers to the Danube River both before and after the construction of the protective measures. At water stages of the Danube River below the specified limit the differences in the outflow are increased and at the minimal water stage of the Danube River of 102.5 m a.s.l. the groundwater outflow (m3.s-1) after the completion of the protective measures is approximately five times lower than it was before the completion of the protective measures.

Fig. 24. Groundwater flow from the aquifer into the Danube River (m3.s-1)

Similarly, for the flow of water from the Danube River to the aquifer the relation may be expressed using the exponential dependence (Fig. 25). At the minimal water stage of the Danube River the dependence is almost the same before and after the completion of the protective measures. The differences in the flows are exponentially increased between the average and maximal water stage of the Danube River and at the high water stage of the Danube River after the completion of the protective measures the flow of water from the Danube River to the aquifer is more than fivefold lower than it was before the completion of the protective measures.

Change of Groundwater Flow Characteristics After Construction of the

territory,

Kendeleš,

protective measures:

surface,

measures:

5. Volumetric budget:

increased by 2.38 m.

Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia 75

• at the average water stage f the Danube River in the Western third of the territory (max. by 1.6 m) and also on the location of Kendeleš (max. by 0.17 m) higher than before the completion of the PMs. Lower (max. by 2.25 m) on the remaining

• at the maximal water stage of the Danube River on the Northern border at the village of Mužla (max. by 1.15 m) and in the proximity of the Kravany channel

• at the minimal water stage of the Danube, the change of the direction of the groundwater flow is significant in the Western half of the territory, from the

• at the average water stage of the Danube River, the groundwater from the area of Kravany flows to the Danube River via both "windows" and not to the location of

• at the maximal water stage of the Danube, the aquifer is supplied from the Danube not alongside its bank length, but only via the "windows" in the underground wall.

• at the minimal water stage of the Danube the maximal depth of groundwater level was reduced by 0.5 m and the minimal depth reached the level of the terrain

• at the average water stage of the Danube the maximal depth of groundwater level was increased by 0.56 m and the minimal depth was reduced by 0.36 m, • at the maximal water stage of the Danube River the maximal depth of the groundwater level was increased by 1.39 m. The piezometric pressure head above

4. The fluctuation of the groundwater level after the construction of the protective

• maximal value of the fluctuation was increased by 0.12 m. The minimal value was

• At water stages of the Danube River below 104.5 m a.s.l. the differences in the outflow of groundwater from the aquifer to the Danube River are increased and at the minimal water stage of the Danube River of 102.5 m a.s.l. the groundwater outflow (m3 s-1) after the completion of the protective measures is approximately five time lower than it was before the completion of the protective measures.

• The differences in the flows are exponentially increased between the average and maximal water stage of the Danube River and at the high water stage of the Danube River after the completion of the protective measures the flow of water from the Danube River to the aquifer is more than fivefold lower than it was before

**Future research** should focus on numerical simulations of the underground dam function in the riparian alluvial aquifer. Underground dam belongs to the management types of artificial hydrogeological groundwater body feeding. It is built in shallow alluvial sediments in order to restrain the immediate underground outflow from the groundwater body. It

3. The groundwater level depth under the terrain surface after the construction of the

(max. by 0.35 m) higher than before the completion of the PMs. 2. The main directions of the flow after the completion of the protective measures:

Northern border of the territory to both "windows",

the terrain surface was reduced by 2.79 m.

Roughly exponential relation applies here.

the completion of the protective measures.

Fig. 25. Flow from the Danube River into the aquifer (m3.s-1)

*Hydrogeological profiles* (Fig. 4 and 5) with displayed characteristic levels of groundwater, when they are plotted perpendicularly to the surface water recipients, allow to specify the assessment of the impact of the immediate influence of the fluctuation of their level onto the fluctuation of the groundwater level, they allow to determine the distance of the drainage effect of rivers, reservoirs, the inclination of the groundwater level and underground inflow to the observed territory or the underground outflow from it. The hydrogeological profiles alongside the rivers are important for the calculations of the overall bank filtration inflow and outflow. They allow to determine the flow regime, whether it is done with a free level or tense level. Finally, they are very graphic prove for the demarcation of the areas with the intensive inflow and outflow of groundwater, i.e. the areas of their accumulation, or drainage.
