Mapping Avalanche Risk Using Gis Technique In Ceahlau

Mapping avalanche risk using GIS technique in Ceahlău Mountain

A. Covăsnianu, I.R. Grigoraş, L.E. State, S. Hogaş

1. Introduction2. Study area 3. Purpose of the paper4. Methodology5. Progress of work6. Results 7. Applications8. Problems occured and future abordation


Avalanche = The sudden fall or slide of a large mass of material down the side of a mountain. Avalanches may contain snow, ice, rock, soil, or a mixture of these materials. Avalanches can be triggered by changes in temperature, by sound vibrations, or by vibrations in the earth itself.

Source: http://www.thefreedictionary.com


ConceptConcept

Statistics- A 35 years statistics for Swiss Alps gives a medium value of 75 human/year covered by avalanches, from which 35/year are recorded dead.

- In French Alps a 28 years statistic presents a medium value of 100 persons/year involved in avalanche, with a “black statistic” of 30 death/year. “Black” years were 1969/1970, 1980/1981 and 2005/2006 with 55-57 victims.

-Romania also has his history of lost lives in avalanches: Bâlea tragedy in 1977, 17th of April (23 skyers dead, most of them young ones); Gutâi - small avalanche in 2004 february 22 (3 dead); the 2003-2004 winter was calamitous: 8 skyers and mountaineers dead until february 24.

Past backgroundPast background in Romania in Romania PhD thesis of Mariei MotoiuPhD thesis of Mariei Motoiu Dinu Mititeanu – articles and publications about avalancheDinu Mititeanu – articles and publications about avalanche Mircea Voiculescu – practical and theoretical materialsMircea Voiculescu – practical and theoretical materials Bogdan Mihai si Ionut Sandric – Digital mapping of avalanche riskBogdan Mihai si Ionut Sandric – Digital mapping of avalanche risk

Part of Eastern Carpathians being situated in the flysch area (conglomerates, calcareous rocks “centrally disposed in a highly elevated synclinal structure”- Irina Ungureanu, 2004)

“Table lands are mostly wavy with high peaks which opposes as aspect with structural surfaces and anticlines. The versants are cut by degrees, having vertical walls (shelfs, “brâne”, fences, karling, chutes).”– by I.Bojoi (2000)

Total area of research: 84.74 km84.74 km22

Potential area : 31.05 31.05 kmkm22


The aim of the study was to map the Potential Release Areas of snow avalanches within Ceahlău Mountain.

The idea of this project came after a course from faculty. Then we continue our research having behind the previous “signals” from media, salvamont service, local community about avalanches in this area.

To evaluate the avalanche risk of those regionsTo represents a useful tool for tourism activity

and not onlyMapping avalanche risk using GIS technique in Ceahlău Mountain

Adaptation by J. HERSKO şi G. BUGAR – 2000

Model updated from Belianske Tatry Mts.

RAv = (S + Ex + Al + Fx) RAv = (S + Ex + Al + Fx) * Rg* Rg

Where,

S= slope Ex= aspectAl=altitudeFx=landformRg=roughness



Digital Terrain Digital Terrain ModelModel was obtained from digitization of topographic maps at 1:5.000 scale.

The result was a model with a 3m cell resolution.

The accuracy of the model was determined by Topo to Raster tool from Esri ArcInfo.


Slope map.

The slope values of more then 35 degrees are representative for evaluating the avalanche risk.

The lowest values of less than 15 degrees slope are in the table land area.


Aspect mapAspect map

The South, South-West and South-East versants are the most representative due to the fact that the avalanche risk is higher in those areas.

Aspect mapAspect map

The South, South-West and South-East versants are the most representative due to the fact that the avalanche risk is higher in those areas.


Landforms map Landforms map describes the concavity/convexity of the terrain.

The landform is very useful for snow avalanche risk because it determines the probable snow accumulation areas or the possible areas of propagation .

The concave areas are mostly represented by the bed’s rivers.

The convex one’s, in general, are represented by the highest slope values.

Study area (31 km2) was divided in 448 cells

Cell size = (125*125 m) = 1.5 ha

Every cell risk coefficient was independently obtained by entering the specific parameters of that area in the final formula.

A class of values of ROA was established.

Finally, for each cell we obtained values varying from 0 to 16.5



The higher probability of producing a snow avalanche is near Toaca Peak and close to Dochia chalet.

Avalanche risk Avalanche risk classes:classes:0-5 = low risk (tourism activity not forbidden in winter season)5-10 = moderate risk (tourism activity permitted only for experienced users)10-15 = considerable risk (tourism activity admitted under certain conditions)15-20 = high risk (restricted under certain conditions).


- The tourist tracks were obtained by GPS technique- Any of those three tourist tracks passes through areas with avalanche risk


Tourism activityTourism activity – a better perception of the area, more info for tourists, prevention, maybe a future interactive webmap (WEBGIS) giving a better precision for tourists routes and for the sectors possibly of being afected

Management of Natural Park Ceahlău Can be applied in similar mountain areas Educational goal


Different editions of topographic mapsLack of GPS data (tourist tracks, avalanche mapping)

Problems occurredProblems occurred::

Future Future abordationabordation::• Taking into account the climatologic data

(solar radiation, wind speed and direction, air temperature, snow texture, consistency) for the future research objective

• A more detail cell size resolution

• Future involvement of the authorities which governs the National Park Mapping avalanche risk using GIS technique in Ceahlău Mountain

Technology

Mapping Avalanche Risk Using Gis Technique In Ceahlau