Alteration of yield and springs number as an indicator of climate changes. Case study of Eastern Poland

Abstract

Groundwater is an extremely important natural resource, exploited for domestic, industrial, and agricultural use. Being a natural groundwater discharge at the topographic surface, springs are also important hotspots of biodiversity. The increasing demand for groundwater and climate change, are major threat to springs worldwide. This study presents the scale and diversity of the process of spring disappearance, as an indicator of continuous climate change. Various criteria: the age of the aquifer, the springs’ outflow character, altitude, and discharge were taken into account. The generalized linear model method was used to assess changes in the number of springs over the study periods, whereas a t-test was used to analyze changes in springs’ yield. Precipitation variation was investigated using the statistical quality control methods. The study showed that both the number of springs and yield decreased significantly in all the classes considered. The total yield of the studied springs decreased over the years 1990–2020 from 6939 L/s to 4285 L/s. 361 springs had disappeared, regardless of topographic setting or aquifer type. An increasing trend of days without precipitation, and sums of precipitation exceeding 0.9 percentile was observed. The changes in annual dynamic of precipitation, favor surface runoff, rather than infiltration, causing springs’ drying-up processes. Even the most abundant Cretaceous aquifer is susceptible to the process. The presented case study shows an immediate need for formal and legal actions, to protect springs as valuable groundwater sources.