Workpackage number: 1

Start date or starting event: Project start date

Lead contractor number: 5 - Pyreneen Institute of Ecology

Person-months per partner: 1-3; 2-2; 3-0; 4-3; 5-56; 6-4

Objectives and input to workpackage

1. Develop quantitative relationships for debris flow characteristics.

2. Assess effect of extreme rainfall characteristics on debris flow magnitudes.

3. Assess the most geomorphologically active areas at hillslope and basin scales in focus area A

4. Assess effect of vegetation cover and land use change on debris flows.

5. Assess importance of debris flow for basin sediment source and sediment yield.

Description of work

Geomorphic mapping in 3 mountain river basins of total area 5500km² in focus area A at 1:50,000 scale to determine spatial distribution of debris flows and sediment sources and to identify the most affected subbasins.

1. Incorporate geomorphic maps into a GIS with the geomorphological, soil hydrological, vegetation cover, and current and past land use characteristics.

2. Field measurement of debris flow characteristics (scar size and gradient, runout distance,  vegetation cover, substrate properties) to provide a database for determining debris flow relationships for improved modelling. Data from all focus areas.

3. Statistical analysis of the information in the GIS, a) to rank the factors explaining debris flow occurrence and related phenomena, and b) to assess probability of debris flow occurrence in the study area.

5. Statistical analysis of meteorological information to classify the rainfall events and to determine their return periods. Assess relationship between rainfall of different return periods and occurrence of debris flows of different magnitude, using historical and present-day data. Data from all focus areas.

Deliverables

D1) Quantitative relationships for debris flow characteristics, including effect of land use and rainfall return period, as input to WP3 and WP4; and debris flow characteristics database, as input to WP5.

D2) Geomorphological map of debris flow characteristics and debris flow occurrence probability map for focus area A, as input to WP5; statistical and cartographic procedures for automatic identification of geomorphologically and hydrologically active basins likely to generate debris flows, as input to WP5.

Milestones and expected result

Month 15: Preliminary debris flow relationships for WP3 and WP4.

Month 21: Final debris flow relationships for WP3 and WP4.

Month 30: Final cartographic products and database, for WP5.

Result: Improved means of predicting debris flow occurrence as function of environmental change. Improved techniques for mapping debris flow characteristics.

---