Małgorzata Stefaniak

Abstract

The Różany Strumień catchment, located in the northern part of Poznań, is one of the research areas of the Integrated Monitoring of the Natural Environment (IMNE) programme and serves as a field laboratory of the Poznań-Morasko station. This is the first IMNE base station in Poland located within a large urban agglomeration and subjected to strong anthropogenic pressures. The 2023 hydrological year marked the eighth year of continuous monitoring in this urban catchment, with investigations carried out in accordance with twelve IMNE measurement programmes. The present paper discusses selected results that together enable an assessment of the functioning of the catchment geoecosystem under the hydrometeorological conditions of 2023.

Meteorological observations showed that the hydrological year 2023 was classified as a warm year. The mean annual air temperature reached 10.4°C, comparable to the recent warm years of 2018-2020 and 2022, and clearly higher than the 1991-2020 long-term average. Only April was classified as a cool month, whereas five months were warm or very warm, including an exceptionally warm September. The annual precipitation total reached 628.4 mm, which was 17% above the long-term average. However, precipitation was extremely unevenly distributed throughout the year. Very wet months (August and October) alternated with extremely dry ones, most notably September with only 5.3 mm of rainfall. Snow cover was insignificant, occurring on a single day in December, and had no impact on catchment retention. The length of the thermal growing season (244 days) matched the multiannual mean, although the lack of thermal winter is a signal of the ongoing climatic shift.

Precipitation chemistry measurements revealed low mineralization and normal pH values, although conductivity remained slightly elevated compared to the long-term reference. Among the anions, nitrates, sulphates and chlorides dominated, whereas ammonium and calcium were the most abundant cations. Compared with previous years, the concentrations of nitrates and sulphates declined, with the nitrate-to-sulphate ratio exceeding unity for the first time, indicating a growing role of traffic-related emissions in precipitation acidity in western Poland. The role of forest canopies in modifying precipitation was also confirmed. Throughfall accounted for about 65% of bulk precipitation, and despite lower volumes, ion loads were nearly four times higher than those of open-field precipitation. This was particularly evident for potassium, magnesium and calcium, which are largely leached from assimilation organs or washed from dust deposits on the canopy surface. Contrary to common expectations that coniferous stands intensify precipitation acidity, the studied Scots pine stand contributed to neutralization instead due to elevated loads of alkaline ions.

Hydrological observations of the Różany Strumień indicated very low water stages and discharges, continuing the unfavorable situation observed since the summer of 2018. Water levels mostly ranged between 14 and 35 cm above the gauge zero, with higher values recorded only in December and August. Discharge fluctuated from zero to 0.0628 m³ ∙ s⁻¹, with an annual mean of 0.0043 m³ ∙ s⁻¹. This was lower than in the dry years 2019-2022 and more than 50% lower than the mean for 2015-2018. A record-high flow variability was noted, and zero-flow conditions occurred for 62 days, mostly in summer and early autumn. These extreme low flows were only occasionally interrupted by short-lived flood waves induced by intense rainfall.

The chemical composition of stream water was characterized by slightly alkaline pH (7.83) and high mineralization, with a mean specific electrical conductivity of 91.5 mS ∙ m⁻¹. The waters belonged to the Ca-HCO₃-Cl hydrogeochemical type. Ion load calculations confirmed bicarbonates, chlorides and sulphates as the dominant anions, and calcium, sodium and magnesium as the main cations. According to national regulations, six of the twelve evaluated indicators corresponded to class I water quality, while four (including conductivity, bicarbonates, calcium and chlorides) were classified below class III. As a result, the overall ecological status of the stream was assessed as below good.

Groundwater levels in two observation wells reflected the pattern of atmospheric supply. After a favorable winter and very wet August, water tables increased, although generally remained at low levels comparable to those observed during the last four years. Both piezometers recorded the lowest minimum groundwater levels since 2016, a legacy of the extremely dry years 2018-2019 and intensified evapotranspiration driven by rising air temperatures. Hydrochemical analyses indicated Ca-HCO₃-Cl waters with mineralization above 500 mg ∙ dm⁻³. Most parameters corresponded to class I groundwater quality, with conductivity, sulphates and chlorides classified as class II, and calcium as class III. Accordingly, the overall chemical status of groundwater was assessed as good, in contrast to the surface waters of the catchment.

The annual water balance revealed a strong dominance of atmospheric input over river discharge (610.8 mm), highlighting the considerable retention capacity of the urban geoecosystem. The dissolved matter balance was negative (-32.6 kg ∙ ha⁻¹), with significant losses of calcium and chlorides, while the nutrient balance was positive (+16.0 kg ∙ ha⁻¹), dominated by nitrates and ammonium. These findings confirm the predominance of leaching processes over accumulation within the catchment and emphasize the role of both natural conditions and anthropogenic impacts in shaping material fluxes. In conclusion, the functioning of the Różany Strumień catchment in 2023 was strongly controlled by variable hydrometeorological conditions and by the increasing anthropogenic pressure typical of urban areas. The study demonstrates the usefulness of integrated monitoring for identifying short-term responses and long-term trends in small urbanized catchments. Continued observations will provide the basis for detecting cause-effect relationships, recognizing environmental risks, and supporting sustainable management strategies under conditions of ongoing climate change and urban expansion.

Keywords: Różany Strumień catchment, IMNE, anthropogenic pressure, water balance, precipitation chemistry, surface waters, groundwater

Maciej Major [maciej.major@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego Poznań-Morasko; Uniwersytet im. Adama Mickiewicza w Poznaniu, Instytut Geoekologii i Geoinformacji
Maria Chudzińska [maria.chudzinska@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego Poznań-Morasko
Robert Kruszyk [robert.kruszyk@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Instytut Geoekologii i Geoinformacji
Mikołaj Majewski [mikolaj.majewski@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Wydział Nauk Geograficznych i Geologicznych
Małgorzata Stefaniak [m.stefaniak@amu.edu.pl], Uniwersytet im. Adama Mickiewicza w Poznaniu, Stacja Zintegrowanego Monitoringu Środowiska Przyrodniczego Poznań-Morasko

Citation

APA: Major, M., Chudzińska, M., Kruszyk, R., Majewski, M., & Stefaniak, M. (2025). Funkcjonowanie geoekosystemu zlewni miejskiej Różanego Strumienia w Poznaniu pod wpływem presji antropogenicznej. Przegląd Geograficzny, 97(4), 427-445. https://doi.org/10.7163/PrzG.2025.4.4
MLA: Major, Maciej, et al. "Funkcjonowanie geoekosystemu zlewni miejskiej Różanego Strumienia w Poznaniu pod wpływem presji antropogenicznej". Przegląd Geograficzny, vol. 97, no. 4, 2025, pp. 427-445. https://doi.org/10.7163/PrzG.2025.4.4
Chicago: Major, Maciej, Chudzińska, Maria, Kruszyk, Robert, Majewski, Mikołaj, and Stefaniak, Małgorzata. "Funkcjonowanie geoekosystemu zlewni miejskiej Różanego Strumienia w Poznaniu pod wpływem presji antropogenicznej". Przegląd Geograficzny 97, no. 4 (2025): 427-445. https://doi.org/10.7163/PrzG.2025.4.4
Harvard: Major, M., Chudzińska, M., Kruszyk, R., Majewski, M., & Stefaniak, M. 2025. "Funkcjonowanie geoekosystemu zlewni miejskiej Różanego Strumienia w Poznaniu pod wpływem presji antropogenicznej". Przegląd Geograficzny, vol. 97, no. 4, pp. 427-445. https://doi.org/10.7163/PrzG.2025.4.4