Evaluation of climate change impact ON
groundwater resources in the Klaipeda district
case study area
The project “Evaluation of climate change impact on groundwater resources and related components of environment in Lithuanian sea coast region (Klaipeda district), elaboration of recommendations for future use and protection of groundwater resources” was performed in 2010. The project was carried out by Dr.MariusGregorauskas (Joint Stock Company „Vilniaus Hidrogeologija“ (Vilnius), under the order by Lithuanian Geological Survey.The investigations were carried out under the auspices of the project “Climate Change: Impacts, Costs and Adaptation in the Baltic Sea Region” (BaltCICA) project. The project is part-financed by the European Union (EU) Baltic Sea Region Programme 2007–2013.The report of the project (in Lithuanian) includes introduction, five main chapters, conclusions, and a list of references. The report comprises 81 pages, including 18 figures and tables, and addendum including 29 figures and 1 table.
The Klaipeda district is located on the Baltic Sea coast, and covers ~1300 km2 and stretches ~40 km inland.
In the area of investigationsall potable water is groundwater located in shallow, Quaternary,Cretaceous, Jurassic and Permian-Famenianaquifers. Groundwater available resources in these aquifers approved by Lithuanian Geological Surveyare 74000 m3/d, 100 m3/d, 1148 m3/d, 8463 m3/d and 63084 m3/d respectively.
76 waterworks are located in the area of investigations. The Klaipeda3rd waterwork is the only waterwork in the country extracting water from shallow groundwater; it extracts 27% of approvedavailable resources. Waterworks extracting water from Jurassic aquifers use 46%, Permian-Famenian aquifers – 23% of approvedresources.The production rate from Cretaceous is almost equal to proven resources.
Climate change impact on groundwater was estimated on the basys of two scenario’s A1B and B1 forthe years 2025, 2050 and 2100. Predictions of precipitation and evaporation were providedusing data base byspecialists from department of Hydrology and Climatology, Vilnius University.
Fig. 1. Groundwater flow model:layout (I) andcross - section (II)
1 –grid; 2–5 –boundary condition, 5–waterfield (Q(t)); 6–boundary of Quaternary confined aquifers; 7 –boundary of K2cm-K1, 8–aquifers (cross - section); 9–low permeable layers(cross - section);
10 –number of layer( cross - section); 11 –cross - section
Forecast of groundwater resources changes was done using mathematical groundwater flow model and was based on correlations between values of precipitation, river basins runoff in the model area and groundwater recharge.
Simulation results show that both climate change scenarios predict increase (2025, 2050 and 2100 years) of dynamic resources of groundwater in the area of investigation. Since the main source of the groundwaterresourcesand cause of its changes is infiltration recharge into shallow groundwater, therefore the highest increase of resources is anticipated in shallow groundwater aquifer. In the A1B case the highest groundwater level is expected in 2025 year. At that time the groundwater recharge will increase from 45.7mm/year to 79.6mm/yearadding todynamic resources from 4.05m3/s to 5.99m3/s. Similar growth of resources is anticipated in B1 case in year 2100.
Increase of groundwater resources declines as a function of depth. If the expected increase of dynamic resources in the shallow groundwater aquifer is~1–2m3/s (1.5times higher than estimated present resources), thenin the Quaternary aquifers, isolated from shallow groundwater by low permeable layers, reach only tenth or hundredth parts of m3/s. It means that resources in Quaternary aquifers will increase only by 2–12%. Deeper Cretaceous and Jurassic aquifers are almost not affected by climate change and the increase of water resources in following aquifers is almost negligible.
Apart from highest increase of resources in 2025 in the A1B case, additional resource peaks are expected in 2043, 2044, 2051, 2070, 2079, 2081 and 2090 years. According to results of simulation the anticipated increase of resources in following years would reach 6m3/s in shallow groundwater and 1.25–1.3 m3/s in Quaternary aquifers. The B1 scenarios predict the main peak in 2100 with additional smaller increase of resources in years 2016, 2078, 2089. According to results of simulation the anticipated increase of resources in following years would reach 5–5.5 m3/s in shallow groundwater and 1.2–1.25 m3/s in Quaternary aquifers.
B1 / A1BFig. 2. Calculated dynamic resources of groundwater for the period 2011–2100
– Shallow groundwater aquifer, –Quaternary confined aquifer, – Cretaceous aquifer
The decrease of resources is expected in years 2021,2022, 2034, 2035, 2038, 2055, 2056, 2072 in A1B case and years 2018,2029, 2034, 2041, 2054, 2062, 2075, 2076, 2082, 2099 in B1 case. According to results of simulation the resourcesin these years will decrease by 4m3/s in the shallow aquifer and 3.8–3.6 m3/s (5–10%) in Quaternary aquifers, compared with present resources.
Changes of groundwater level in main aquifers arecorrelatedwith increase of groundwater recharge and dynamic resources. In 2025 and 2100 years highest increase of recharge is predicted in shallow groundwater, thusaverage annual groundwater level could rise in sandy lenses by 2.5–2.8 m, in till and peat – 0.2–0.5 m, in the remainingpart of the territoryin shallow groundwater aquifer – by 1–1.5 m, in Quaternary aquifers –0.3–0.5m, in Cretaceous aquifer – 10cm and in Jurassic aquifers will remainpractically unchanged.
2025 B1 / 2050 B1 / 2100 B1Fig. 3.Predicted fluctuation of shallow groundwater level
Conclusion could be made, that neither in 2025, 2050, 2100 years,nor during all investigated time period there is nodanger for groundwater resourcesdecrease. In the times when decrease of dynamic resourcesis predicted, average annual groundwater level in shallow groundwater could fall to 10–15 cm. In the Klaipeda3rdwell field area and in Quaternary and Cretaceous aquifers –just up to several centimeters.
As it is mentioned above, the climate change will notaffect water resources in Jurassic aquifers. Moreover, it is obvious that climate change will not affectresources in deeper Permian-Famenian aquifer, which is overlaid by non-permeable Triassic aquitard 110–250m thick, thoughit was not included into simulation model.
Overall conclusion of the project is that trend of increase groundwater resources will prevail until 2100. However, increasing levels of shallow groundwater will increase vulnerability of groundwater pollution and risk of inundation in number of low laying areas.