VTEI / groundwater

groundwater

Groundwater abstraction noticeably reduces the flow of some watercourses during the dry season

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The paper highlights the fact that some significant watercourses dry up during periods of minimal flows due to groundwater abstraction. It provides a summary of the most affected significant watercourses in the Czech Republic. Large concentrated groundwater abstraction has a considerable impact on small and medium-sized watercourses. To select the most significant effects of abstraction on stream flows, we used the ratio of abstraction to 355-day flows from 1931–1960. Watercourses exceeding 30 % were selected. In half of the selected cases the following relationship was confirmed: the 355-day flow from 1931–1960, reduced by the abstraction rate, is approximately equal to the 355-day flow from 1991–2020. The cases where this relationship does not apply can be explained by changes in abstraction volumes, declining groundwater levels and flows in the wider area due to groundwater collection and the use of static groundwater reserves. The effect of climate change is unlikely to be present in the baseflow in the cases studied. Our analysis identified 13 cases where groundwater abstraction is severely affecting the flow of significant watercourses. In about half of these cases, there is an alternative source of water that should be used when the flow of the watercourse is at a minimum. Another option to protect water resources is to apply the minimum groundwater level or minimum residual flow under the Water Act.

Old groundwater in hydrogeological regions 4410 and 4522

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The article presents a project from the Technology Agency of the Czech Republic dealing with the hydrogeology of old waters in hydrogeological regions 4410 and 4522. The aim of the paper is to present a brief hydrogeological characterization of the area of interest, to present the results after the first year of the project, and to describe the uncertainties of existing information. Old groundwaters that have negligible concentrations of tritium can be considered a strategic resource because they are less susceptible to current contamination.

Methodology for creating a Map of the Vulnerability of the Quantity of Natural Groundwater Resources to Drought for the Czech Republic

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Groundwater drought affecting groundwater availability is still mostly understood as a subset of hydrological drought. The impact of hydrological drought on groundwater is manifested with a delay and depends on its duration. An expert interactive Map of the Vulnerability of the Quantity of Dynamic Groundwater Resources to Drought for the Czech Republic was created as part of the TA CR project SS01010208 – “Controlled Groundwater Recharge as a Tool to Reduce the Impacts of Drought in the Czech Republic”. The presented vulnerability map is created on the basis of the use of precipitation normal and regression relationships between precipitation and total runoff and groundwater discharge (base flow) using the Base Flow Index (BFI) and ratio of base flow in the driest year of 2010–2019 to the long-term average of base flow (M index), which guarantees uniform processing for the entire Czech Republic at a scale of 1 : 50,000 and an objective comparison of the vulnerability of dynamic groundwater resources to drought throughout the country. It is also based on recorded groundwater abstraction and in the case of municipalities with individual supply, the abstraction is calculated from the number of inhabitants and the national average consumption of drinking water per capita. The Map is compiled based on the balance of dynamic groundwater resources and groundwater abstraction. It contains six categories and shows which regions and areas will struggle to have sufficient groundwater resources during periods of prolonged drought. It synthesizes all available flow logs and other data until 2020 and is designed so that the layers with variable information can be updated in the future.

Development of land use and impact on water resources of hydrogeological unit 4232 Ústecká syncline in the Svitava river basin

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The research area of hydrogeological unit 4232 Ústecká Syncline in the Svitava river basin (Ústecká synklinála v povodí Svitavy) is an important area of underground drinking water sources. These resources are of the highest quality and among the most abundant resources in the entire Czech Republic. The development of land use is closely connected with the development of settlements and industry (textile) in the research area, which in their importance far exceeded the borders of the region. Gradual development created pressure on natural resources, especially water; the demands on the quantity of service and drinking water increased, while the quality of water was affected by industrial and agricultural pollution. Despite the observed decrease in population in the last twenty to thirty years, we can see the expansion of settlements, mainly due to new construction on agri-cultural land, which is slightly compensated by the expansion of permanent grasslands and forests. With regard to current and future climate change, this increase, together with a slight increase in water bodies, can be considered as a positive phenomenon.

Drought warning system and local threshold limits

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Droughts and floods are extreme hydrological phenomena that are currently increasing in frequency due to the growing impact of climate change, and can have significant effects on our lives. Within the “PERUN” research project, an assessment of drought conditions and their development in the Czech Republic is being developed, along with the innovation of the warning system by the Czech Hydrometeorological Institute (CHMI). Drought is a natural phenomenon characterized by a gradual onset, long duration, and low dynamics, which requires a specific approach. The amendment to the Water Act introduces the obligation of regular reporting on drought and the establishment of a predictive service to be conducted by CHMI. Tools are being developed for long-term prediction of water resource conditions and a methodology for drought and water scarcity management plans. These plans aim to ensure water supply, protect the environment, and minimize the economic impacts. The decision-making body for issuing measures based on the drought plans is the Drought Commission, which operates at the regional level. The warning information is available on the HAMR web portal, which also displays local threshold limits for individual water resources.

Groundwater formation in urban areas regarding peripheral parts of Prague

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Groundwater is an integral part of the hydrosphere and hydrological cycle in a healthy landscape, which is better able to withstand hydrological extremes such as floods or prolonged drought. The main source of groundwater is precipitation. There are a number of barriers for infiltration in urban areas – urban and industrial buildings, as well as increasing areas with impermeable surfaces. The aim of the paper is to draw attention to the importance of groundwater in the urban landscape and to possible measures to support the infiltration of precipitation.
The research took place in the territory of outer Prague, where there is an intensive expansion of the built-up area, which is accompanied by a lower infiltration of precipitation, compared to the open landscape. Based on the evaluation of pedological, geological and hydrogeological conditions of the area, a methodology for evaluating the suitability of the area for infiltration was developed. Based on it, two types of maps were created: an infiltration potential map evaluating primarily the permeability of the soil and rock environment, and an infiltration capacity map, in addition emphasizing the size of the free storage volume for infiltrated water. Maps are available for viewing in the map application on the project website heis.vuv.cz/projekty/praha-adaptacniopatreni.

Baseflow evolution from the part of Bohemian-Moravian Highlands

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This article is focused on evolution of baseflow from part of the Bohemian-Moravian Highlands. This is a topical issue and, given the current situation, is also often discussed. The problem of groundwater and its recharge is an important (not only) hydrogeological problem, as climatic conditions in recent years, especially low precipitation, have a negative impact on groundwater recharge.