The paper discusses the water resources of the Krężniczanka River catchment. The catchment with an area of 224.9 km2 is located south-west of Lublin. The characteristics of the groundwaters and runoff were determined based on hydrological and hydrogeological materials of the Department of Hydrology of the Maria Curie-Skłodowska University (UMCS). Mean runoff in the period from 2010 to 2016 amounted to 125.7 mm, precipitation 629.4 mm, and evapotranspi-ration 503.7 mm. A strong relationship was determined between the rhythm of runoff and ground-water level fluctuations. The contribution of groundwater supply in total runoff equalled 81.5%.

Lublin Upland and Roztocze region are known for the occurrence of a large number of springs of high yield. These springs are fed mainly from Cretaceous or Tertiary water-bearing horizon. In order to determine variability of springs’ yield, 61 selected springs were analysed in spring periods of the years 1998–2008. Collected hydrometric materials allowed for comparing average and extreme yield values of springs in various physiographic regions within the period of 11 years. Average value was 76.1 dm3·s–1, while the mean of the minimal yields was 44.7 dm3·s–1 and of the maximal – 132.7 dm3·s–1. Coefficient of irregularity of the springs’ yield ranged from 1.5 to 5.0, which may lead to the conclusion that the springs’ yield is constant or varies slightly. In some cases the irregularity was higher but it was determined by hydrogeological, meteorological and local factors.

Appropriate design in linear construction depends on many factors, including detailed geological conditions. One of the biggest problems are unrecognized erosion forms, in particular karst ones, which have a huge impact on the design and subsequent operation of roads. For this purpose, in addition to conventional methods such as drilling or geotechnical probing, which are point-based, non-invasive spatial geophysical methods are used. This article presents an example of the use of geoelectrical surveys, Electrical Resistivity Tomography (ERT) for the recognition of karst zones for linear investments. The article describes ERT investigations, which to some extent allows to identify dangerous karst phenomena occurring in the Lublin Upland (Poland), which are of great importance at the design stage of roads and in their further safe operation. Non-invasive geophysical research has been verified and confirmed by traditional geotechnical research, which confirms the effectiveness of their use. The Electrical Resistivity Tomography was used as a method providing a broader spectrum of knowledge on the spatial arrangement of soil layers in the subgrade of the planned road investments. It also enabled a more accurate, more detailed interpretation of geotechnical studies. The described geophysical investigations opens wide possibilities for their application to researchers. In the future, non-invasive methods have a chance to become as reliable as geotechnical methods, but this requires a lot of research to improve the effectiveness and accuracy of the interpretation of the obtained results.