This document analyzes spatial and temporal trends in meteorological, hydrological, and hydrogeological data in the San River Basin in Ukraine from various weather stations and monitoring points over time. Statistical tests were used to analyze trends in monthly average temperature, precipitation, discharge, surface water level, and groundwater level. The results found significant increases in average monthly temperatures across most stations. Precipitation and discharge did not show significant trends, while surface water levels significantly decreased and groundwater levels showed both decreasing and increasing trends depending on location within the basin. The study concludes the data confirms remote sensing observations of decreasing groundwater levels in plains and varying trends in mountains.

1. Spatial and Temporal Trend Analysis of
Meteorological, Hydrological and
Hydrogeological Data (by the Example of the
San River Basin)
Davybida L.*, Worsa-Kozak M., Górniak-Zimroz J., Michalak A.
Ivano-Frankivsk National Technical
University of Oil and Gas
Wroclaw University of Science and Technology
International Conference of Young Professionals
«GeoTerrace-2021»
4-6 October 2021, Lviv, Ukraine

2. Study area of the San River Basin

3. according to the NASA Earth Observatory [https://earthobservatory.nasa.gov/]
Signs of Drought in European Groundwater in June 2020

4. Representative weather stations, results of correlation analysis for meteorological
observations and graphs of precipitation and temperatures for the station with the
longest observation period

5. Land use map and examples of different trends in the groundwater level
fluctuations

6. The Mann-Kendall (MK) test
,
S - 1
,
if S > 0
var(S)
Z 0, if S 0
S 1 if S 0
var(S)
 
 







The magnitude (Sen`s slope) of a time series trend is evaluated by a
simple non-parametric procedure developed by Sen (Sen 1968):
Rank based non-parametric MK test (Mann, 1945, Kendall, 1975) is used for
detection significant trends. The MK test is widely used in detecting trends in
time series data in meteorology and hydrology fields (Suryavanshi et al., 2014;
Zhou et al., 2016; Kisi et al., 2018, Azam et al., 2018, Malik et al., 2019, Yilmaz
et al., 2020, ...).
If Z>0, it indicates an
increasing trend, and vice
versa.
The test statistic Z is denoted by equation:

7. Map showing the significance of trends and the spatial patterns of Sen`s slopes
for monthly average temperature
There is a statistically
significant increase in
the variability of
average monthly
temperatures for almost
all weather stations.

8. Map showing the significance of trends and the spatial patterns of Sen`s slopes
for monthly precipitation
The obtained results do not
confirm the presence of
long-term trends in the
monthly precipitation series
for the study area. For the
majority of weather stations
(with the exception of
“Yavoriv” with a negative
trend and “Jarocin” with a
positive one), the trends are
not statistically significant.

9. Map showing the significance of trends and the spatial patterns of Sen`s slopes
for monthly average discharge
No significant increases or
decreases in the stream
discharge were observed
during the monitoring
periods for the majority of
gauge stations with only a
few exceptions.

10. Map showing the significance of trends and the spatial patterns of Sen`s slopes
for monthly average of surface water level
Slightly different results
were obtained for the
average monthly water
levels at the gauging
stations. There is a
significant decrease in the
water levels altitudes for
most observation points.

11. Map showing the significance of trends and the spatial patterns of Sen`s
slopes for monthly average of groundwater level
In the case of groundwater
levels, different trends are also
observed. There is a certain
territorial regularity, and
decreasing tendencies in
groundwater levels series of
different aquifers are typical
for the wells, which are located
in the plain part of the basin,
while increasing trends or
absence of significant changes
are normal for the
mountainous area.

12. Conclusions & Acknowledgements
 The results of the MK test indicate the presence of divergent trends in
the studied time series.
 Differences in the formation of long-term variability of surface and
groundwater levels compared to the dynamics of hydrological
discharges, temperatures and precipitation may be explained by the
higher level of anthropogenic factors influence (hydraulic engineering,
water use, melioration) on the formation of water levels.
 In general, the results of the analysis of current and historical ground-
based observations from the monitoring points within the territory of the
San river basin confirm the data of global remote sensing. Decreasing
tendencies in groundwater levels series of different aquifers are typical
for the wells, which are located in the plain part of the basin, while
increasing trends and absence of statistically significant changes are
normal for the mountainous area.
 This research was prepared with the support of the Centre for East
European Studies (University of Warsaw) in the frame of the Ivan
Vyhovsky Award (2020/2021).

13. International Conference of Young Professionals
«GeoTerrace-2021»
4-6 October 2021, Lviv, Ukraine
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attention!