Aim of the study:
The aim of the study was to assess the relationship between groundwater level, drought at aquifer, precipitation deficit and high air temperature.

Material and methods:
The analyses were developed on the basis of data from the Faculty of Agro- and Hydrometeorology Observatory of the Wrocław University of Environmental and Life Sciences in Wrocław-Swojec covering years 1969–2017. Data were provided by measurements of groundwater level as well as temperature and precipitation. Using Standardized Precipitation Index (SPI) for precipitation and Standardized Temperature Index (STI) for temperature, periods with precipitation deficit and raised temperature were identified. The research also determined the relation between these indicators and groundwater level. Drought periods at groundwater level have been estimated using a Standardized Groundwater Level Index (SGI).

Results and conclusions:
Analysis of the relationship between STI and the groundwater level showed low correlation. The air temperature as a single factor has no clear impact on the groundwater level at the shallowestaquifer. For precipitation, the strongest relationship appeared between SPI6 and the groundwater level. Seasonal meteorological drought has the greatest impact on decreasing the groundwater level. It was found that an extremely dry period with SPI registered < –2 caused a decrease of the groundwater table in 1969–1970, 1972–1974, 1976, 1978, 1992–1993, while in 1979, 1983–1984, 1989–1992, 1994–1995, 2003, 2004, 2006, 2015 the level dropped due to very high deficits in precipitation with SPI between –2 and –1.5. The decreasing groundwater table, as a result of precipitation deficits, was not always directly connected to droughts at the described groundwater level. The longest periods of groundwater decrease occurred in 1980, 1981, 1986/1987, 1994, 1997/1998, 2000, 2001, 2006/2007, 2017. In addition, 14 periods of extreme drought were recorded.