Surface morphological types and spatial distribution of fan-shaped landforms in the periglacial high-Arctic environment of central Spitsbergen, Svalbard

Figures & data

Figure 1. Location of the study area with extent of the Main Map 1 marked in red. Basemap data and background satellite imagery provided by © Norsk Polar Institute (http://www.npolar.no).

Figure 2. Geological map of the study area. The map is based on Geological Map of Svalbard 1:250,000 provided by © Norsk Polar Institute (http://geodata.npolar.no).

Figure 3. Examples of fluvial-flow-dominated fan surface morphology: (a) ground-based view of active and older inactive braided channels visible on the fan surface; (b) orthophoto of braided pattern of fluvial channels; (c) fluvial-flow-dominated fan with incised channel in the most proximal part and a network of active and older inactive braided channels in a more distal one. Note also that large part of this fan is vegetated.

Figure 4. Examples of debris-flow-dominated fan surface morphology: (a) ground view of recent debris flow channel; (b) orthophoto of the debris-flow-dominated fan depicting a dense network of recent (‘fresh’) and older debris flow channels and lobes (c) ground view of older, partly levelled, debris flow channels.

Figure 5. Examples of colluvial fan surface morphology: (a) oblique view of short and steep colluvial fans located along the fjord margin; (b) an NIR (false colour: Near Infrared – Red – Green) composite satellite image of a colluvial fan with recently modified areas emphasized by a light grey colour. The older parts of the fan are shown in green. Note also that the inactive parts of the slope between fans are vegetated and therefore highlighted in near-infrared (red in the image). Source: © Digital Globe; (c) ground-view of coalescing colluvial fans.

Table 1. Definitions, types and units, range of values and source of calculated morphometric properties of fans and their catchment areas.

Feature	Description	Type and unit	Values of the attributes	Data source
Fan type	Fans were visually delineated from the orthophotos and DEM with guidance from watershed, flow direction and flow accumulation raster. Types defined based on visual interpretations from orthophotos and satellite imagery, taking into account: relief, recognizable deposits and landforms (debris-flow levees, debris-flow lobes, etc.), patterns of channels (e.g. braided), colour variations and surface patterns	Nominal	Colluvial fans Alluvial fans: • Debris-flow-dominated fans • Fluvial-flow-dominated fans	Orthophoto, high-resolution satellite imagery, DEM, field surveys
Fan long-profile	Topographic profiles over most recent active surface drawn in accordance with the fan radius	Nominal	Straight	DEM
			Slightly concave
			Concave
			Markedly concave
Fan cross-profile	Topographic profiles perpendicular to the fan radius. Cross-profiles were measured on the proximal, middle and distal part of each fan	Nominal	Flattened	DEM
			Plano-convex
			Plano-convex with a flattened top
Fan relationship	Fan relation with neighbouring fans	Nominal	Solitary form	Orthophoto and high-resolution satellite imagery
			Coalescing on one side
			Coalescing on both sides
Fan dominant aspect	Direction of maximum slope which covers at least 50% of fan area	Nominal	e.g.: North	DEM
			Northeast
			East
			Southeast
			South
			Southwest
			West
Fan mean profile curvature	Mean value of curvature of the terrain measured in the direction of the steepest slope – it is measured as the radius of the curvature and expressed as 1/100 m	Continuous (1/100 m)	−1.4–1.8	DEM
Fan mean plan curvature	Mean value of curvature of the terrain measured in the direction of the contour of the slope – it is measured as the radius of the curvature and expressed as 1/100 m	Continuous (1/100 m)	−1.9–1.8	DEM
Fan area	The planimetric area of the fan	Continuous (m^2)	325–451,275	DEM
Fan mean slope	The mean slope of the whole fan area calculated as the average value of slope of all raster cells within fan area	Continuous (°)	5–37	DEM
Fan apex (m a.s.l.)	The elevation of the fan apex	Continuous (m)	22–657	DEM
Fan toe (m a.s.l.)	The lowest elevation at the fan toe	Continuous (m)	0–566	DEM
Fan relief	The elevation difference between the fan apex and the fan toe	Continuous (m)	19–314	DEM
Fan length	Length measured over a straight line joining the fan apex and the fan toe	Continuous (m)	42–1436	DEM
Fan width	Length measured at the greatest width of the fan area	Continuous (m)	13–899	DEM
Catchment dominant aspect	Direction of maximum slope which covers at least 50% of the catchment area	Nominal	e.g.: North	DEM
			Northeast
			East
			Southeast
			South
			Southwest
			West
			Northwest
Catchment area	The planimetric area of the catchment	Continuous (m^2)	400–2,050,850	DEM
Catchment mean slope	The mean slope of the whole catchment area calculated as the average value of slope of all raster cells within a catchment area	Continuous (°)	17–60	DEM
Maximum elevation of the catchment (m a.s.l.)	The highest point/elevation of the catchment boundary	Continuous (m)	129–1022	DEM
Catchment relief	The elevation difference between the maximum elevation of the catchment and the fan apex	Continuous (m)	44–887	DEM
Catchment length	Length measured over a straight line joining the fan apex and the location of maximum elevation of the catchment	Continuous (m)	51–2232	DEM
Catchment width	Length measured at the greatest width of the catchment area	Continuous (m)	12–1251	DEM

Table 2. Outcomes of morphometric features per fan type for fans located in Petuniabukta region, Svalbard – Part I.

Morphometric features	Fan type
	Colluvial fans (n = 229)	Debris-flow-dominated fans (n = 49)	Fluvial-flow-dominated fans (n = 19)
Fan area (m^2)	8750 (325–156,175)	57,550 (2725–340,925)	58,450 (6550–451,275)
Fan mean slope (°)	37 (31–10)	11 (7–25)	8 (5–13)
Fan apex (m a.s.l.)	299 (67–657)	161 (42–510)	112 (22–314)
The lowest point at the fan toe (m a.s.l.)	168 (2–566)	26 (0–365)	15 (0–236)
Fan relief (m)	119 (29–314)	108 (40–253)	87 (19–144)
Fan length (m)	208 (42–945)	501 (147–1243)	475 (132–1436)
Fan width (m)	70 (13–381)	244 (39–893)	318 (95–899)
Catchment area (m^2)	10,750 (400–402,575)	199,800 (5500–772,450)	410,725 (56,650–2,050,850)
Catchment mean slope (°)	38 (10–37)	34 (7–25)	29 (17–32)
The highest point of the catchment (m a.s.l.)	505 (129–985)	712 (317–934)	686 (318–1022)
Catchment relief (m)	178 (44–528)	473 (132–801)	554 (190–887)
Catchment length (m)	233 (33–1385)	813 (137–1530)	1211 (606–2232)
Catchment width (m)	74 (12–514)	333 (65–878)	462 (137–1251)

Note: Presented values are median, minimum and maximum, respectively.

Table 3. Outcomes of morphometric features per fan type for fans located in Petuniabukta region, Svalbard – Part II.

Morphometric features	Fan type
	Colluvial fans		Debris-flow-dominated fans		Fluvial-flow-dominated fans
	Number of fans	% of all fans	Number of fans	% of all fans	Number of fans	% of all fans
Number of fans	229	77	49	16	19	6
Fan long-profile
Straight	135	45	13	4	6	2
Slightly concave	54	18	11	4	5	2
Concave	33	11	16	5	6	2
Markedly concave	7	2	9	3	2	1
Fan cross-profile
Flattened	182	61	18	6	6	2
Plano-convex	36	12	31	10	13	4
Plano-convex with a flattened top	11	4	0	0	0	0
Fan relationship
Solitary form	90	30	20	7	12	4
Coalescing on one side	83	28	13	4	5	2
Coalescing on both sides	56	19	16	5	2	1
Dominant fan aspect
North	14	5	2	1	1	0
Northeast	21	7	0	0	0	0
East	13	4	9	3	1	0
Southeast	47	16	11	4	0	0
South	19	6	11	4	7	2
Southwest	16	5	0	0	0	0
West	51	17	1	0	3	1
Northwest	40	13	10	3	3	1
Other dominant aspect directions	8	3	5	2	4	1
Fan mean profile curvature
<−0.1 (markedly convex)	7	2	1	0	0	0
≥ −0.1 and <0 (convex)	18	6	5	2	4	1
0 (straight)	1	0	0	0	0	0
>0 and ≤0.1 (concave)	50	17	26	9	10	3
>0.1 (markedly concave)	153	52	17	6	5	2
Fan mean plan curvature
<−0.1 (markedly convex)	47	16	14	5	4	1
≥ −0.1 and <0 (convex)	22	7	10	3	8	3
0 (straight)	0	0	0	0	0	0
>0 and ≤0.1 (concave)	32	11	21	7	7	2
>0.1 (markedly concave)	128	43	4	1	0	0
Dominant catchment aspect
North-northwest	11	4	5	2	1	0
East	10	3	3	1	0	0
East and northeast	15	5	3	1	0	0
East and southeast	6	2	4	1	0	0
Southeast	39	13	5	2	2	1
South-southeast	11	4	8	3	4	1
Southwest-west	11	4	0	0	1	0
South	11	4	7	2	2	1
Southwest	18	6	0	0	1	0
West	36	12	0	0	1	0
West-northwest	11	4	3	1	0	0
Northwest	24	8	1	0	2	1
Other dominant aspect directions	26	9	10	3	5	2

Figure 6. The lithology of the catchments of colluvial and alluvial fans in Petuniabukta.

Note: ‘dominated’ – means that the specified lithological unit occupied more than 50% of the catchment area; ‘and other’ – means that each of the specified lithological units occupied less than 50% of the catchment area.