Summary of the professional content of the aid application. The sustainable use of groundwater resources, which are an invisible part of the terrestrial water cycle, can be hampered by a number of factors. In the framework of the application, we intend to describe innovative and forward-looking water management solutions and/or test them under field conditions in three interlinked modules: The first module examines the relationship between (1) subsurface flow conditions and climate change aspects. Extreme weather trends have a clear impact on terrestrial water roundabouts, and it is necessary to develop new methods for analysing this in different depth ranges, which have not been applied so far, as groundwater supply can change significantly in the future, which may have serious water management implications. Adverse water management effects are caused by the deterioration of soil structure as a result of cultivation (2) and the creation of a soil compaction zone, which significantly reduces the leakage factor and the water capacity of the soils and their ability to reservoir, thereby affecting natural infiltration and replenishment processes. As a result of this phenomenon, the potential for inland water and droughts is significantly increased in a given area. In Hungary, the 20-30 % operating network loss of (3) water utilities providers is a major challenge, which is not only a waste of resources for water abstraction for drinking water of 700 million m³ per year, but also a serious economic loss. We see new possibilities to identify hidden water leaks and pipe fractures by indirect methods. A detailed description of the research activities and results to be implemented. New procedures to understand the effects of extreme weather conditions on groundwater replenishment and flow regimes (Prof. Dr. Péter Szűcs) Extreme weather conditions have a clear impact on the dynamics of terrestrial water circulation. The supply of groundwater resources may change significantly in the future, which may have serious water management implications. Based on the results of the Kútfő (TÁMOP 4.2.2.A-11/1/KONV-2012-0049) project, we intend to continue research at international level that will be possible to analyse hydrological cycles for water management purposes using the toolkit of environmental isotopes and geoinformation processing in many domestic plots. The analysis of long-term hydrological data sets can be effectively complemented by the development of special monitoring systems and the innovative use of different environmental isotopes. Special spectral analysis and processing of hydrological and hydrogeological data can give new directions in hydrological cycle analysis and water management decision preparation. We wish to cooperate with MTA ATOMKI regarding the measurement and processing of environmental isotopes. Methods to be used: 1.1. Infiltration measurements using natural isotopes in the saturated medium. In the last 5 years, we have carried out studies in Méntelek, Kecskemét, Fischerbocs, Kéleshalmon, Debrecen and Nyíradony for the isotopy-drogeological examination of groundwater replenishment. In the course of which we used several levels of filtered, special groundwater detection well nests and well groups. Our patented procedure (registration number: 4555) using a tritium profile can be used to determine the temporal change in infiltration conditions in both the unsaturated and saturated media, from which simulations can be used to deduce changes in the subsurface flow systems over time. In the framework of the application, we intend to increase the number of sample areas, especially in the Great Plain, in order to provide more accurate information on the main infiltration areas. On the other hand, in addition to tritium, stable and radioactive isotopes may be measured to clarify the infiltration values and their evolution over time. 1.2. Time continuous soil moisture content measurement in the aeration zone. On the campus of the University of Miskolc, a complex hydrogeological — hydrometeorological station was established, including a monitoring tool that measures the water content of the unsaturated medium at different depth levels depending on time. Thus, it is possible to monitor the level of infiltration of the saturated medium in the given test site for different precipitations. 1.3. Statistical and spectral evaluation of hydrological time series. In addition to spectral analysis of long-term hydrological datasets (mainly based on Fourier transformation), tests based on the principle of factor analysis and the most common values make it possible to determine the impact of extreme weather conditions on the hydrological cycle and underground flow systems. 1.4. Hole geophysical tests: Monitoring of underground flows, their characteristics (leakage factor)