Morphometric analysis on the size, shape and areal distribution of glacial cirques in the maritime alps (western french-italian alps)

• Published in: Geografiska annaler. Series A, Physical geography Vol. 86; no. 3; pp. 235 - 248
• Main Authors: Federici, Paolo Roberto, Spagnolo, Matteo
• Format: Journal Article
• Language: English
• Published: Oxford, UK and Boston, USA Taylor & Francis 01-01-2004; Blackwell Science Ltd; Swedish Society for Anthropology and Geography; Blackwell; Svenska sällskapet för antropologi och geografi
• Subjects: Alpine glaciers; Altitude; Areal geology. Maps; Bgi / Prodig; Cirque glaciers; cirque morphometry; Cirques; Digital elevation models; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geologic maps, cartography; Geomorphology; Geomorphology, landform evolution; Geomorphometry; GIS; glacial cirques; Glacial landforms; Marine and continental quaternary; Massifs; Perpendicular lines; Physical geography; Surficial geology; Topographical elevation; Valleys; Western Alps; Alps; Western Alps; Italian Alps; French Alps; Alpes-Maritimes France; Southern Europe; Italy; France; Western Europe; Alpes-Maritimes; Alps (The); Europe; altitude; models; maps; Europe; digital elevation models; geographic information systems; morphometry; shape analysis; slopes; spatial distribution; cirques; correlation; valleys; landform evolution; direction; Geomorphometry; Digital elevation model; Cirque; Mountain; Geographical information system
• ISSN: 0435-3676; 1468-0459
• DOI: 10.1111/j.0435-3676.2004.00228.x

The morphometry of 432 glacial cirques in the Maritime Alps (Western French-Italian Alps), studied over several years of fieldwork, was analysed with the use of a geographical information system. Some of the parameters automatically evaluated from digital elevation models required an objective and relatively new definition. In particular, cirque length was measured along a line that, from the threshold midpoint, splits the cirque into two equivalent surfaces; cirque width was automatically drawn as the longest line inscribed in the cirque and perpendicular to the length line. Significant correlations were found among the different factors and parameters analysed. In particular, cirque shape analysis showed that cirques develop allometrically in the three dimensions, i.e. more in length and width than in altitudinal range. Nevertheless cirques of the Maritime Alps have a regular, almost circular shape (mean L/W value = 1.07). The correlations among length, width and area are all very high (r
2
= 0.8-0.9). In terms of size, cirques show a wide range in area from 0.06 to 5.2 km
2
with a mean value of 0.4 km
2
. The largest cirques are found on SSW-facing slopes and at high elevations. Small cirques can be found at all altitudes but all those at high elevation are part of compound cirques at the main head valleys. Most cirques (37%) are characterized by a northern aspect; NE and SW are also frequent directions.