Causes and Effects of Coastal Dunes Erosion During Storm Surge Axel in January 2017 on the Southern Baltic Polish Coast

Łabuz, Tomasz Arkadiusz

doi:10.14746/quageo-2023-0024

Figures & Tables

The Polish Baltic coast.
A – coastline with sandbars’ location, a – coast kilometrage 0–428, b – rivers, c – lakes and lagoons, d – main towns. B – sandbars’ morphology, a – height, b – width. C – the average trend of coast dynamics with kilometrage division (Łabuz 2013), a – accumulative, b – stable, c – erosive, d – no data. D – analysed sections of the coast, highest sea level (SL) and wind roses during Axel, a – investigated sandbars, see Table 3, b – gauge stations, c – maximum sea level. E – location change of artefacts washed from the land and shifted by surge Axel (Table 4), a – from location A to new position A’, b – No. of shifted kilometres. — The Polish Baltic coast. A – coastline with sandbars’ location, a – coast kilometrage 0–428, b – rivers, c – lakes and lagoons, d – main towns. B – sandbars’ morphology, a – height, b – width. C – the average trend of coast dynamics with kilometrage division (Łabuz 2013), a – accumulative, b – stable, c – erosive, d – no data. D – analysed sections of the coast, highest sea level (SL) and wind roses during Axel, a – investigated sandbars, see Table 3, b – gauge stations, c – maximum sea level. E – location change of artefacts washed from the land and shifted by surge Axel (Table 4), a – from location A to new position A’, b – No. of shifted kilometres.

Fig. 2.

Forms measured along the profile and indicators of their dynamics (B – before the surge, A – after the surge). DHbe – beach height change; DKfr – foredune top/edge change; DPfr – foredune foot change; DQbe – beach sand volume change; DQfr – foredune sand volume change; DWbe – beach width change; ALw – water line after the surge; BLw – water line before the surge; SL – sea level; SLr – water run-up; Wbe – beach width.

Examples of dune retreat caused by lower surges in 2016 and Axel in 2017.
A – two cutoffs of the dune after October and November surge (black lines) vs large erosion after Axel surge, Hel Spit 33 km H. B – cut off during November surge vs retreat after January 2017 (red line), Kashubian Sandbar, 170 km. C – erosion after October and November surge vs retreat after January 2017 (red line), Resko Lake Sandbar, 341 km; 1–5 – the same clumps of pine trees. — Examples of dune retreat caused by lower surges in 2016 and Axel in 2017. A – two cutoffs of the dune after October and November surge (black lines) vs large erosion after Axel surge, Hel Spit 33 km H. B – cut off during November surge vs retreat after January 2017 (red line), Kashubian Sandbar, 170 km. C – erosion after October and November surge vs retreat after January 2017 (red line), Resko Lake Sandbar, 341 km; 1–5 – the same clumps of pine trees.

Dune erosion related to beach height, coast orientation and SL during low surges in 2016 and Axel in 2017.
A – concave bay on the west coast exposed to NNE. B – cutoff of the promontory exposed to NE on the Hel Spit. C – concave bay with high beach exposed to NW from the middle coast. D – retreat of promontory exposed to NW on the east coast. a – erosion during surges in 2016, b – erosion during Axel in 2017, c – morphodynamic bars (dynamic layer) every 1 m and total volume of the eroded dune (DQfr) or embryo dune (DQed), d – the height of surge run-up to the shore (HSLr). — Dune erosion related to beach height, coast orientation and SL during low surges in 2016 and Axel in 2017. A – concave bay on the west coast exposed to NNE. B – cutoff of the promontory exposed to NE on the Hel Spit. C – concave bay with high beach exposed to NW from the middle coast. D – retreat of promontory exposed to NW on the east coast. a – erosion during surges in 2016, b – erosion during Axel in 2017, c – morphodynamic bars (dynamic layer) every 1 m and total volume of the eroded dune (DQfr) or embryo dune (DQed), d – the height of surge run-up to the shore (HSLr).

Phases of wind course during storm surge Axel in 2017 (SW to GD – gauge stations).
A – NW to NNW, rapid SL growth. B – N to NNE, maximum surge. C – NNE, slow SL drop. D – NNE to NE, wind decrease and sea level drop.
Source: windy.com. — Phases of wind course during storm surge Axel in 2017 (SW to GD – gauge stations). A – NW to NNW, rapid SL growth. B – N to NNE, maximum surge. C – NNE, slow SL drop. D – NNE to NE, wind decrease and sea level drop. Source: windy.com.

Wind and sea level course during storm surge Axel in 2017 (SW–GD – main gauge and wind stations, see Fig. 1).

Relation of surge parameters to mean (sign), average (line) and max. value of erosion rate during surge Axel in 2017.

Relation of dune toe retreat (DPfr) to sea level (HSL) along the Southern Baltic coast during surge Axel in 2017.

Relation of sea level (HSL) to water run-up height (HSLr) on the coast during all surges in 2016/2017, each dot marks measured SLr in the field, surges in Table 1.

Relation of dune toe erosion (DPfr) to beach height (Hbe) in total during the Axel surge in January 2017.

Overall relation of dune toe erosion (DPfr) to beach parameters (Hbe, Wbe) rate in January 2017.

Relation of dune toe erosion (DPfr) to beach height (Hbe) on investigated sandbars divided for coast sections (Nos 1–20, Table 3) and Pearson coefficient (r) in January 2017.

Erosion rate of the dune on the coast with different expositions during storm Axel, given toe retreat (m) and sand volume in grey (m3) of dune or embryo dune (ed), marked max. run-up and dates of dune’s previous position.

Statistical threshold values of the dune toe erosion caused by storm Axel, on investigated sandbars’ sections (Table 3).
a – average, b – median, c – 25–75 percentile of cases, d – min. and max. values. — Statistical threshold values of the dune toe erosion caused by storm Axel, on investigated sandbars’ sections (Table 3). a – average, b – median, c – 25–75 percentile of cases, d – min. and max. values.

Dune retreat along Polish South Baltic coast during storm Axel in January 2017.
a – dune retreat (m), b – washover fans on the coast, c – no data, cliff coast or wetlands in bays, d – main kilometre division, e – names of main sandbars. — Dune retreat along Polish South Baltic coast during storm Axel in January 2017. a – dune retreat (m), b – washover fans on the coast, c – no data, cliff coast or wetlands in bays, d – main kilometre division, e – names of main sandbars.

Coefficients correlation of selected input and output variables of storm surge Axel in January 2017_

Dependent variables	Max. SL (H_SL, m)	SL length (T_SL H > 0.8 m, h)	SL length (T_SL H > 1.0 m, h)	SL length (T_SL H > 1.2 m, h)	Max. run-up (H_sLr, m)	Dune toe retreat (DP_fr, m)
Independent variables	Max. SL (H_SL, m)	SL length (T_SL H > 0.8 m, h)	SL length (T_SL H > 1.0 m, h)	SL length (T_SL H > 1.2 m, h)	Max. run-up (H_sLr, m)	Dune toe retreat (DP_fr, m)
Max. SL (H_SL, m)	×	0.40	0.82	0.76	0.62	0.42
SL length (T_SL H > 0.8 m, h)	0.40	×	–	–	0.38	0.17
SL length (T_SL H > 1.0 m, h)	0.82	–	×	–	0.51	0.45
SL length (T_SL H > 1.2 m, h)	0.76	–	–	×	0.75	0.42
Max. wind vel. (V_w, m · ^s−1)	0.79	0.18	0.50	0.49	0.83	0.83
Time V > 10 m · s⁻¹ (V_w, h)	0.70	0.72	0.81	0.83	0.86	0.39
Max. run-up (H_SLr, m)	0.62	0.01	0.40	0.43	×	0.55
¹ Beach height before (H_be B, m)	×	×	×	×	×	0.49

Characteristics of storm surges during autumn–winter 2016/2017 along Polish gauge stations (location in Fig_ 1D)_

No.	1	2	3	4	5	6	Mean SL [m]
Date	4–6.10.2016	3–4.11.2016	27–28.11.2016	12–14.12.2016	27–28.12.2016	4–6.01.2017	–
Name	Angus	NN	NN	NN	Barbara	Axel	–
Wind velocity (m · s⁻¹)	13–17	11–14	12–15	11–14	13–18	13–18	–
Wind direction	NE–NNE	W–NNW	WNW–NNW	W–WNW	NW–N	NW–NE	–
Świnoujście (SW)	1.13	0.48	0.93	0.66	0.90	1.42	0.92
Kołobrzeg (KG)	0.63	0.53	0.72	0.64	1.12	1.50	0.86
Darłowo (DA)	0.42	0.44	0.56	0.55	0.89	1.65	0.75
Ustka (US)	0.40	0.46	0.56	0.53	0.88	1.45	0.71
Łeba (LE)	0.42	0.40	0.57	0.47	0.74	1.23	0.64
Wład. (WA)	0.54	0.32	1.01	0.46	0.92	1.36	0.77
Hel (HE)	0.36	0.25	0.71	0.44	0.84	1.05	0.61
Gdansk (GD)	0.40	0.18	0.82	0.35	0.75	1.18	0.61
Mean SL (m)	0.54	0.38	0.74	0.51	0.88	1.36	0.74

Characteristics of the transported large items during storm surge Axel (location in Fig_ 1E)_

No.	Item characteristics	Weight in ca. kg	No. of travelled km	Azimuth, from–to	Shift (sandbar/town, coast kilometrage start-end)
A	Wooden platform 5 m × 5 m	20	8	E–WNW	Świnoujscie to Ahlbeck, from 426 toward the west
B	Wooden board 6 m × 2 m	8–10	11	E–WNW	Międzyzdroje to Świnoujscie 411–422
C	Metal garbage can 1 m × 0.5 m	5	12	WSW–NNE	Rega, 350–338
D	Plastic parts from coast protection 0.5 m × 0.5 m	1–2	16	W–NE	Jamno to Bukowo, 300–284
E	Metal garbage can 1 m × 0.5 m	3–4	15	W–NE	Kopań, 270–258
F1	Wooden and metal construction/military aim 8 m × 5 m	5–8	9	W–ENE	Wicko, 242–233
F2	Wooden and metal construction/military aim 5 m × 5 m	3–5	29	W–NE	Wicko to Gardno, 242–213
F3	Wooden and metal construction/military aim 5 m × 5 m	4–6	39	W–NNE	Wicko to Łebsko, 242–203
F4	Wooden and metal construction/military aim 5 m × 5 m	4–6	46	W–NNE	Wicko to Łebsko, 242–196
G	Plastic parts from coast protection 0.5 m × 0.5 m	1–2	10	NW–SE	Karwia, 140–131
H	Wooden and plastic parts from harbour 2 m × 3 m	3–6	45	W–E	Vistula, 75–30
I	Floating trunk wood from Vistula river mouth, several, largest 12 m × 1 m	30–50	12–17	W–E	Vistula, 49–37 (32)

Characteristics of the Axel January 2017 storm surge along Polish gauge stations (location in Fig_ 1D)_

Harbour, gauge station	Świnoujście (SW)	Kołobrzeg (KG)	Darłowo (DA)	Ustka (US)	Łeba (LE)	Władysławowo (WA)	Gdańsk (GD)
Location of harbour	53°55’N 14°16′E	54°11’N 15°33′E	54°26’N 16°22′E	54°45’N 16°51’E	54°46’N 17°33’E	54°47’N 18°25’E	54°21’N 18°39’E
Wind V max [m · s⁻¹]	14–15	14–16	15–18	13–15	14–15	12–16	12–14
Wind duration V > 10 [m · s⁻¹] (t, h)	62	65	57	54	55	50	42
Storm duration H > 0.8 m (t, h)	39	36	30	33	31	34	27
Storm duration H > 1 m (t, h)	28	26	23	20	14	19	11
Storm duration H > 1.2 m (t, h)	18	15	12	9	3	7	0
Max. SL, 4 Jan (h)	10	10	11	11	14	14	17
Max. sea level [m AMSL]	1.42	1.50	1.65	1.45	1.23	1.36	1.18

List and date of investigated sandbar sections, average dune toe erosion and selected SL parameters during Axel storm surge (location in Figure 1A, C)_

No.	Investigated sandbar name/part	Length [km]	Measurement date, before, after surge (month)		Average dune toe retreat (m)		SL > 1 m (t, h)	Max. SL in gauge station, SL [m]	Max. run-up on the shore, SLR [m]	Harbour (gauge station), location
No.	Investigated sandbar name/part	Length [km]	Before, in 2016	After, in 2017	Mean	Median	SL > 1 m (t, h)	Max. SL in gauge station, SL [m]	Max. run-up on the shore, SLR [m]	Harbour (gauge station), location
1	Świna Gate	16	9, 11, 12	1, 4	5.4	5.7	28	1.42	3.9	Świnoujście (SW) 53°55N 14°16E
2	Dziwnów	11	9	1, 6	7.3	7.5	28	1.42	3.7
3	Liwia Lake to Rega river	15	9	2, 4	4.4	4.1	28	1.42	3.8
4	Resko Lake to Parsęta river	14	9, 11	2, 5	6.0	5.9	26	1.50	3.7	Kołobrzeg (KG) 54°11N 15°33E
5	Jamno Lake	11	9	2, 9	6.2	5.2	26	1.50	3.7	Kołobrzeg (KG) 54°11N 15°33E
6	Bukowo Lake	12	9	1, 9	9.4	9.8	23	1.65	3.9	Darłowo (DA) 54°26N 16°22E
7	Kopań Lake	10	9	1, 9	8.4	9.0	23	1.65	4.1	Darłowo (DA) 54°26N 16°22E
8	Wicko Lake	15	6	3, 6	5.3	4.0	20	1.45	3.8	Ustka (US)
9	Gardno Lake	10	9	4, 9	3.6	3.0	20	1.45	3.6	54°45N 16°51E
10	Lebsko Lake 1/west/Czołpińska Dune	10	9, 11	4, 9	5.4	3.5	14	1.23	3.5	Łeba (LE) 54°46N 17°33E
11	Lebsko Lake 2/east/Łącka Dune	16	9, 11	4, 9	5.0	2.7	14	1.23	3.5
12	Sarbska Sandbar	9	9, 11	4, 9	4.5	3.1	14	1.23	3.4
13	Kaszubska 1/west/Stilo Dunes	7	9, 11	4, 9	7.9	8.0	14	1.23	3.4
14	Kaszubska 2/middle/Lubiatowska Dune	6	9	5, 6	5.5	4.2	19	1.36	3.4	Władysławowo (WA) 54°47N 18°25E
15	Kaszubska 3/east/Biała Góra Dune	9	9, 11	5, 9	3.6	1.8	19	1.36	3.5
16	Karwia	12	9, 11	6	4.9		19	1.36	3.6
17	Hel Spit	35	9, 11	4, 6	6.8	8.0	19	1.36	3.8
18	Vistula Sandbar 1/west/channel mouth	10	11	2, 6	2.3	2.1	11	1.18	3.7	Gdańsk (GD) 54°21N 18°39E
19	Vistula Sandbar 2/middle part	19	11	4, 6	4.2	4.1	11	1.18	3.7	Gdańsk (GD) 54°21N 18°39E
20	Vistula Sandbar 3/east/Camel Hump Dune	24	11	6	4.4	4.5	19	1.36	3.9	Władysławowo (WA) 54°47N 18°25E

Causes and Effects of Coastal Dunes Erosion During Storm Surge Axel in January 2017 on the Southern Baltic Polish Coast

Figures & Tables

Fig. 1.

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Fig. 11.

Fig. 12.

Fig. 13.

Fig. 14.

Fig. 15.

Coefficients correlation of selected input and output variables of storm surge Axel in January 2017_

Characteristics of storm surges during autumn–winter 2016/2017 along Polish gauge stations (location in Fig_ 1D)_

Characteristics of the transported large items during storm surge Axel (location in Fig_ 1E)_

Characteristics of the Axel January 2017 storm surge along Polish gauge stations (location in Fig_ 1D)_

List and date of investigated sandbar sections, average dune toe erosion and selected SL parameters during Axel storm surge (location in Figure 1A, C)_

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