International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
RESULTS FROM 1996 TO 2003
Fire Activity in Nicaragua
In Nicaragua, the majority of fires occur during the dry season,
from December until the end of May. Five successive seasons had
been monitored since the installation of the system and its
products had been widely distributed under different forms: lists
with coordinates, tables and regional maps. These activities have
improved the awareness among the different stakeholders related
with the management of natural resources and the early detection
of the fire forest at national and local level as well.
Description of the data
The AVHRR (Advanced Very High Resolution Radiometer) of
the NOAA satellites permit the monitoring of actives fires on
large area coverage. The quantitative values given through thermal
infrared channels of the AVHRR sensor are used to detect
vegetation fire through the ignition effect above the irradiative
temperature (Malingreau 1990). Proper detection of fire is made
by using contextual algorithms that automatically extract and
select hot pixels with the highest probability of being active fires
(Flase et al 1996). All the results are expressed in terms of hot
spot (Pixels) selected by the contextual algorithm.
The analysis of the data are made by using Geographic
Information System and taken into consideration some contextual
aspects (land cover, Type of forest, rate of poverty).
The table 1, shows the number of hot points detected during five
monitored seasons (January-May 1999-2003). Fire activities differ
from year to year and from region to region. This table present
the early fire activities starting in 2003 (January) with a total of
5914 events for the whole season, meanwhile the activity for 1999
CONTEXTUAL ANALYSIS OF THE FIRE ACTIVITY
With the purpose to know and understand the fire dynamic
related to other aspects, were selected five municipalities of each
region presenting the highest density of hot spot ( table 3) .
Aspects such as Number of hot spot, percentage of forest
coverage, population density, percentage of rural poor population
and Municipality Human Development Index (MDHI) were
analyzed.
The table 3 show the an relations between the municipalities with
highest forest coverage and the incidence of hot spot, being the
municipalities of the Atlantic coast presenting this characteristic
despite’ of the high rate of humidity and the low density population
(10 inh/km?). However, the Atlantic Region owns the largest
forest coverage of the country, and since 1989, have experiencing
an illegal timber harvesting and the clearing of large forest area
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appear by February, this sensible drop in 1999 (2609 hot spot)
probably was caused by the Niña event, which for the month of
march caused unusual rainfall in the Atlantic Coast of Nicaragua.
These analysis can be realized for the whole Meso America, since
there is information available to this region. The figure 1 show the
driest month (April) presenting the incidence of fire for the record
of 1999 —2003), this month
temperature of 38.5.
Although the NOAA satellite have demonstrated the possibility to
delivering-up-to date information derived from the AHVRR,
specially with regard to fire activity, underestimation still remain
in regard to the real numbers of fires for several reasons:
Only the active fires at the moment of the image capture are really
detected.
Cloudy conditions are a negative factor for fire detection.
The context algorithm always acts as a conservative system.
The limited spatial resolution permits detection of fires with a
minimum size of 50 x 100 meters (Belward et al 1993).
Mes/año 2000 | 2001 | 2002 | 2003
Enero | ----- 202 170 209 544
Febrero 94 402 523 364 545
Marzo 222 627 | 1022 | 488 | 1715
Abril 1,328 | 3909 | 2498 | 2821 | 2659
May 965 - = 1391 | 451
Total 2,609 | 4213 | 4213 | 5273 | 5914
Table 1 Number of hot spot detected in Nicaragua
during five monitored seasons.
for cropland and pasture. One of the municipality seriously
affected each year for the fire activity is Prinzapolka, which have
occupied during the years of 2001 and 2003 the first place in
numbers of events, in comparison with the others municipalities
(table 3).
Worldwide is recognized the strong relationship between the
threaten of the fire resources and poverty in the developing
countries. Nicaragua is no the exception above all, 45.6 % of its
population is below of the limit of the poverty (EMNV 2001). In
the table 3 is perceived the strong link between fire incidence and
the phenomena of poverty and low Human development, Most of
the municipalities showed in the table, present a rate of poverty
over the 50 % and low MHDI as well (0.376-4.86).
present an annual average of
Inter
April |
Ab
