National Institut of Meteorology and Hydrology


Soil Moisture Deficit Index of Fire Danger

The fire danger rating on the vegetation land surface is based on the Soil Moisture Deficit Index of Fire Danger (SMDIFD), developed by NIMH. SMDIFD is a measure of vegetation susceptibility to fire ignition and spread regarding the severity and duration of local-scale soil-vegetation system dryness. Different levels of fire risk are introduced by a 6-level threshold scheme that is visualized by a colour-coded map covering the main administrative units of Bulgaria, issued daily in operational mode for two land cover types (winter wheat field and perennial Lucerne/grass).

The calculations and analyses are performed for the region of indicated (*) synoptic station within each administrative unit. The calculative procedure is performed by the following methodology:

  • Numerical description of site-scale biogeophysical cycling by 1D (vertical) meteorological ‘SVAT_bg’ model, developed at NIMH. The model quantifies the coupled energy and water transfer processes in soil-vegetation-atmosphere continuum, accounting for the specific soil and geophysical characteristics, as well as weather conditions. As model outputs, vegetated land surface water cycle characteristics (evapotranspiration and soil moisture along the root zone depth, among the others) are derived.
  • A threshold scheme, developed for designating the quantity of Soil Moisture Availability for the specific vegetation land cover type, based on soil moistening data derived by SVAT_bg. Considering drought as a specific state of biogeophysical cycle, in this aspect the threshold scheme is applied to indicate disturbances in land surface water cycle and the severity of ‘dry anomalies’ in soil-vegetation system.

SMDIFD is jointly used with other materials in the forecasting environment for issuing warnings and specialised forecasts by NIMH-BAS for fire risk at extreme conditions.

The development and operational implementation of SVAT_bg model as well as analyses of land surface processes and extreme states (drought, fire risk, overmoistenins, etc) are performed by Department of Meteorology (Agrometeorology) and Department of Forecasts (Remote sensing). These meteorological products are intended for exploiting by national institutions to ensure the safety of the population as well as for providing meteorological support to economic activities like agriculture, forestry, sustainable development of natural recourses.

For more information:
(+359) 2 974 44 09, (+359) 884 40 86 70
(+359) 2 462 4603

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