Transient Hazard Model Using Radar Data for Predicting Debris Flows in Madison County, Virginia

Abstract The June 27, 1995, storm in Madison County, Virginia produced debris flows and floods that devastated a small (130 km 2 ) area of the Blue Ridge in the eastern United States. Although similar debris-flow inducing storm events may return only approximately once every two thousand years to the same given locale, these events affecting a similar small-sized area occur about every three years somewhere in the central and southern Appalachian Mountains. From physical examinations and mapping of debris-flow sources, paths, and deposits in Madison County, we develop methods for identifying areas subject to debris flows using Geographic Information Systems (GIS) technology. We examined the rainfall intensity and duration characteristics of the June 27, 1995, and other storms, in the Blue Ridge of central Virginia, and have defined a minimum threshold necessary to trigger debris flows in granitic rocks. In comparison with thresholds elsewhere, longer and more intense rainfall is necessary to trigger debris flows in the Blue Ridge.

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Impact of rainfall spatial aggregation on the identification of debris flow occurrence thresholds

10.5194/hess-2017-308 ◽

2017 ◽

Cited By ~ 1

Author(s):

Francesco Marra ◽

Elisa Destro ◽

Efthymios I. Nikolopoulos ◽

Davide Zoccatelli ◽

Jean Dominique Creutin ◽

...

Keyword(s):

Debris Flow ◽

Early Warning ◽

Debris Flows ◽

Spatial Organization ◽

Radar Data ◽

Rain Gauge ◽

Spatial Aggregation ◽

Scale Parameters ◽

The Impact ◽

Triggering Rainfall

Abstract. The systematic underestimation observed in debris flows early warning thresholds has been associated to the use of sparse rain gauge networks to represent highly non-stationary rainfall fields. Remote sensing products permit concurrent estimates of debris flow-triggering rainfall for areas poorly covered by rain gauges, but the impact of using coarse spatial resolutions to represent such rainfall fields is still to be assessed. This study uses fine resolution radar data for ~ 100 debris flows in the eastern Italian Alps to (i) quantify the effect of spatial aggregation (1–20-km grid size) on the estimation of debris flow triggering rainfall and on the identification of early warning thresholds and (ii) compare thresholds derived from aggregated estimates and rain gauge networks of different densities. The impact of spatial aggregation is influenced by the spatial organization of rainfall and by its dependence on the severity of the triggering rainfall. Thresholds from aggregated estimates show up to 8 % and 21 % variations in the shape and scale parameters respectively. Thresholds from synthetic rain gauge networks show > 10 % variation in the shape and > 25 % systematic underestimation in the scale parameter, even for densities as high as 1/10 km−2.

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Map of rainfall, debris flows, and flood effects of the June 27, 1995, storm in Madison County, Virginia

10.3133/i2623a ◽

1999 ◽

Keyword(s):

Debris Flows ◽

Madison County ◽

Flood Effects

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A Rural County Speech and Language Program

Language Speech and Hearing Services in Schools ◽

10.1044/0161-1461.0804.250 ◽

1977 ◽

Vol 8 (4) ◽

pp. 250-255 ◽

Cited By ~ 1

Author(s):

Hildegarde Traywick

Keyword(s):

Public Schools ◽

Speech And Language ◽

Rural County ◽

Language Program ◽

The Public ◽

Madison County

This paper describes the organization and implementation of an effective speech and language program in the public schools of Madison County, Alabama, a rural, sparsely settled area.

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