**6. Conclusions**

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 surface, the amplitude of the underground level, the lines of development of changes of the groundwater level in time, volumetric budget and hydrogeological profiles. For the purpose of the assessment of the change of the characteristics of the groundwater flow after the construction of the protective measures of the Nagymaros waterworks the condition before the construction of the protective measures was analysed and compared with the condition after the construction of the protective measures (the PMs.) The results imply that:

	- at the minimal water stage of the Danube River higher than before the erection of the PMs on the prevailing portion of the territory of interest (max. by 3.45 m), It is lower on the location of Búčšska lúka and Pod kopanicami (max. by 1.45 m),
	- 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 Northern border of the territory to both "windows",
	- 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 Kendeleš,
	- 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 surface,
	- 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 the terrain surface was reduced by 2.79 m.
	- maximal value of the fluctuation was increased by 0.12 m. The minimal value was increased by 2.38 m.

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

*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

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 surface, the amplitude of the underground level, the lines of development of changes of the groundwater level in time, volumetric budget and hydrogeological profiles. For the purpose of the assessment of the change of the characteristics of the groundwater flow after the construction of the protective measures of the Nagymaros waterworks the condition before the construction of the protective measures was analysed and compared with the condition after the

• at the minimal water stage of the Danube River higher than before the erection of the PMs on the prevailing portion of the territory of interest (max. by 3.45 m), It is lower on the location of Búčšska lúka and Pod kopanicami (max. by 1.45 m),

construction of the protective measures (the PMs.) The results imply that:

1. The groundwater level is after the construction of the protective measures:

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

0.00E+00

drainage.

**6. Conclusions** 

1.00E-01

2.00E-01

3.00E-01

4.00E-01

**Flow from the Danube into aquifer (m3.s-1)**

5.00E-01

6.00E-01

7.00E-01

8.00E-01

y = 4E-44e0.9145x R2 = 0.9516

> y = 5E-33e0.6643x R2 = 0.9721

Before protective measures After protective measures


**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

**4** 

Adelana Michael

*Australia* 

**Changes in Groundwater Level Dynamics** 

**Resource Management in a Semi-Arid Climate** 

Groundwater has long been and continues to serve as a reliable source of water for a variety of purposes, including industrial and domestic uses and irrigation. The use of generally high-quality groundwater for irrigation dwarfs all other uses (Burke, 2002); and there are a number of aspects of water quality that have to be managed in such circumstance (e.g salinity, Sodium Absorption Ratio, nutrients, depending on the circumstances of the irrigation). As such there is the need to understand the various implications for use in the

Effective management of groundwater is highly dependent on appropriate reliable and upto-date information (Adelana, 2009) as may be contained in a groundwater database (GDB). According to FAO (2003a), there are currently thousands of local and personal databases storing key technical and licensing data in a very unsatisfactory manner (mostly in terms of usable formats). Hence, the hard evidence required for the assessment of global trends in groundwater depletion and aquifer degradation is still lacking. It is therefore difficult to assess the extent to which global food production could be at risk from either over-

A study on groundwater and food security conducted by FAO (2003a) revealed that compiling reliable groundwater-level and abstraction data (to determine depletion rates) was fraught with problems of coverage, consistency and reliability. Therefore obtaining reliable time-series data on groundwater levels in specific aquifers in many countries may be key to assessing global trend and invariably future impact on food security. The complete lack of a GDB is seriously constraining the formulation and implementation of effective groundwater management policies in many countries. This reinstates the importance of consistency and reliability of groundwater level monitoring for effective groundwater management. In order to ensure sustainable management groundwater level responses must be considered in relation to climate changes and in response to increased agricultural

In the context of varying climatic conditions and frequent lower than average annual rainfall, observed groundwater responses vary and subsequently reduce recharge, stream flow, and the water balance. For example, over the last ten years, decrease in rainfall amount

**1. Introduction** 

food production.

management of groundwater resources.

abstraction or from groundwater quality deterioration.

**in Aquifer Systems – Implications for** 

*Department of Primary Industries/Future Farming Systems Research* 

consists of impermeable wall situated along surface flow, which is dropped to the neogene. Artificial groundwater body feeding, which results from integrated surface and groundwater utilization and long lasting sub-surface accumulation, is preferred where it is possible. Artificial feeding has important role by repeated water utilization, because it gives also quality advantages (water clarifying in soil and in groundwater bodies). In order to utilize the underground reservoir for the storage of significant water amount with the intention to utilize it in later period, it is necessary to discover potential accumulation capacity of the groundwater reservoir as well as its convenience for feeding from surface water and easy pumping in the case of necessity. Groundwater reservoir should show sufficient free space between surface terrain and groundwater level for the water storage and water reservation from feeding during the period when the water is not necessary.

### **7. Acknowledgment**

Author would like to express thanks to the Grant Agency of Slovak Academy of Sciences VEGA for the financial support from projects No 2/0123/11 and No 2/0130/09.

### **8. References**

