Water isotopes in monitoring artificial groundwater recharge and validating the 3D groundwater flow model results

Transcription

1 Water isotopes in monitoring artificial groundwater recharge and validating the 3D groundwater flow model results Nina Hendriksson, Geological Survey of Finland GTK Sami Saraperä & Aki Artimo, Turku Region Water Ltd.

2 Outline Introduction of the Virttaankangas artificial groundwater recharge (AR) project Isotopic separation method (δ 18 O & δ 2 H) 3D flow model 26 weeks flow simulation and isotope observations in the test phase of AR Validating 3D groundwater flow model results by water isotopes 2

3 Artificial Groundwater Recharge (AR) Method: Basin recharge of river water into the unconsolidated glaciofluvial formation with continuous uptake Target: A natural purification and treatment process for surface water (e.g. NOM removal, alkalization) Infiltration rate: from m 3 /d (test phase) to m 3 /d (production) 3

4 Virttaankangas AR Project (operated by Turku Region Water Ltd.) AR scheme active since 1999 Start up of plant in Dec 2011 Infiltration water from River Kokemäenjoki Managed aquifer area in glaciofluvial Virttaankangas Formation, with sediments up to 100 m of thickness Water supply for the 300,000 inhabitants in the Turku region 4

5 Isotopic separation method (δ 18 O & δ 2 H) : Two component mixing system 5

6 δ 2 H Isotopic separation method (δ 18 O & δ 2 H) : Two component mixing system Isotopically distinct water reservoirs as end-members Natural tracer: To quantify mixing of infiltrated surface water and local groundwater Mass-balance To control water residence times Groundwater River water δ 18 O 6

7 3D flow model Littoral sand Silt and clay Glaciofluvial fine Glaciofluvial coarse Till Hydrologeological units of the aquifer were integrated into 60-layer groundwater 3D flow model Based on The esker core unit represents the main aquifer in terms of groundwater flow and water production 3D hydrogeological model (8 km x 10 km) of a subglacial esker Cell size: formation 50 m x 50 m x 2 m In total, roughly 1.94 million cells Bedrock Artimo et al

8 3D flow model, by Artimo et al. Turku Region Water Ltd. Flow of infiltrated water in 26 weeks simulation of AR with infiltration and pumping rates of m 3 /d 8

9 Flow simulation with isotope observations in the test phase of AR plant 0 weeks 26 weeks test phase began Sep 2010 Unique isotope tracer test!! Infiltration ponds Water intake wells 1 km 1 mile 3D flow model by Turku Region Water Ltd. 9

10 1 week 10

11 2 weeks 11

12 3 weeks 12

13 4 weeks 13

14 5 weeks 14

15 6 weeks 15

16 7 weeks 16

17 8 weeks 17

18 9 weeks 18

19 10 weeks 19

20 11 weeks First wells 20

21 12 weeks 21

22 13 weeks 22

23 14 weeks 23

24 15 weeks 24

25 16 weeks 25

26 17 weeks 26

27 18 weeks 27

28 19 weeks All wells 28

29 20 weeks 29

30 21 weeks 30

31 22 weeks 31

32 23 weeks 32

33 24 weeks 33

34 25 weeks 34

35 26 weeks Eastern side K51 K54 K53 K52 1 km 1 mile 35

36 Infiltration area Well Vol of ARG plume reaching well Vol of total capture zone plume Ratio of plume size = ARG % ARG % from O-18 -isotopes ARG % from SCAN (in situ TOC/DOC) Validating the 3D groundwater flow model with water isotope results IA401 K51 IA501 K52 IA503 K53 IA500 K Mm 3 Mm Mm Mm Mm Mm Mm Mm ARG % = per cent of artificially recharged groundwater 36

37 Percent of infiltrated water (%) Validating the 3D groundwater flow model with water isotope results 40 Eastern side Gw flow model O18 isotopes SCAN (TOC/DOC) IA401 - K51 IA501 - K52 IA503 - K53 IA500 - K54 37

38 Thank your for your attention! 38