bUCAO WATERSHED CHARACTERIZATION - Phil

Transcription

BUCAO WATERSHED CHARACTERIZATION
I.
INTRODUCTION AND BACKGROUND INFORMATION
Bucao Watershed is considered as the largest Watershed in
Zambales and one of the most important watersheds in the
municipality of Botolan, Zambales as it is the source of water for
Bucao River supporting the major irrigation system of the
municipality. The watershed also serves as the source of economic
opportunities for the communities as most of the families are
dependent on the watershed resources for their livelihood.
It is located in the provinces of Zambales and Tarlac and
covers a total land area of more or less 68,145.77 Ha. , 7,681.34
Ha. lies in San Jose and Capas Tarlac and about 60,464.43 Ha.
lies in Botolan, Cabangan, San Marcelino, Iba and San Felipe,
Zambales wherein 55,401.58 Ha. is within the town of Botolan.
There are 2 barangays included in the Province of Tarlac namely
Maamot and Sta. Juliana.Whereas 28 barangays comprises the
Province of Zambales distributed into the five towns namely: Sta Fe
in San Marcelino, Balincaguing in San Felipe, Cadmang-Reserva in
Cabangan, and Sta Barbara in Iba while the 23 remaining
barangays are found in the town of Botolan namely as follows, from
the east are the Barangays of Moraza, Villar, Palis, Nacolcol,
Burgos, Maguisguis, Cabatuan, Belbel, Poonbato, Owaog-Nibloc &
Malomboy. Wheras Western barangays included San Juan,
Taugtog, Mambog, Batonlapoc, Paudpod, Carael, Porac, Paco,
Tampo, San Miguel, Beneg and Bangan.
The watershed originate in the Eastern portion of Zambales
mountain range which included Mt. Pinatubo, Mt. Gatas, Mt.
Cahapatan, Mt. Iba and Mt. Mangkirat going down to the West and
finally exits down to the mouth of South China Sea.
The major tributaries of the watershed are the Balinbaquero
river, Maraunot river, Cabatuan river and Baquilan river all of which
are located in Botolan, Zambales.
1
Natural forest vegetation and different wildlife species are
prevalent within the watershed area for several decades. However,
due to indiscriminate logging activities, frequent occurrence of
forest fires, kaingin making coupled with the eruption of Mt.
Pinatubo and recently the intensive mining activities caused the
depletion of these resources.
This watershed characterization activity aims to generate
data and basic information as the of present status of the
watershed
which
will
be
the
basis
in
formulating
and
conceptualizing workable plans for Bucao Watershed consistent
with
the
sustainable
management
strategy
of
the
government.(Figure 1 Geographic Location)
2
Figure 1 Geographic Location of Bucao Watershed
3
II.
PRESENT STATE OF THE WATERSHED
The eruption of Mt. Pinatubo in June 1991 is the main cause
of devastation of Bucao Watershed. The proximity of the watershed
to the volcano resulted to the total destruction of the vegetation
within the nearby areas with tons of sand, stone and ashes over 50
meters high. The flow of drainage pattern was heavily affected due
to soil erosion and lahar flow.
At present, there are Five (5) major sub watersheds (Figure
2) that drain or support the entire Bucao Watershed.namely: (1)
Pinatubo sub watershed with an area of 23,202.31 hectares (2)
Balintawak Sub watershed – 15,052.76 hectares,(3) Bucao II Sub
watershed, area of 13,855.92 hectares (4) Bucao I Sub watershed
with an area of 9,903.40 hectares, and (5) Baquilan Sub watershed
having an area of 6,131.38 hectares.
Because of the continuous stabling condition after the
eruption of Mt. Pinatubo, the affected communities within Bucao
Watershed are starting to revert to their previous areas.
4
Figure 2 Sub watersheds of Bucao Watershed
5
2.1
PHYSICAL ENVIRONMENT
2.1.1. GEOPHYSICAL LOCATION
Table 1. Land Cover by Province, Municipality and Barangay
6
Bucao Watershed is located on the central part of the
province of Zambales, under the administrative jurisdiction
(Figure3) of CENR Office of Botolan (Figure 2). Bounded on the
North by the municipalities of Iba, Zambales, and San Jose and
Capas, Tarlac; on the South by municipalities of Cabangan, San
Felipe and San Marcelino: on the West by South China
Sea/Philippine Sea: and on the East by the province of Tarlac. It is
geographically located at 120° 13’ 39” longitude and 15° 15’1.60”
latitude. It has an approximate area of 68,145.77 hectares with a
total perimeter length of 226,268 m.
7
Figure 3 Administrative map
8
2.1.2. TOPOGRAPHY/GEO-MORPHOLOGICAL FEATURES
Slope of Bucao watershed is flat to moderately rolling to
relatively steep. Elevation ranges from 16 meters to 1,740 meters
above sea level. The slope of 0-8 percent which is about 3.80
percent of the area falls within the coastal barangays of municipality
of Botolan.
The slope of 8-18 which is 1.6 percent of the area covers
mostly the central part of the watershed. The slope of 18-30 which
represents about 0.85 percent is distributed to all parts of the
watershed. The 30-50 slope categories covers roughly 2.3 % of the
entire watershed located along foot slopes of the watershed’s
mountain ridges. While the remaining areas falls within the 50 and
above slope category with 91.45 %.
The aspect map of Bucao Watershed is depicted in figure 5.
Generally, the watershed is northeasterly exposed during the
months of November to February and on the southwest from April
to September.
9
Figure 4 Topographic Map
10
Figure 5 Aspect Map
11
A.
Watershed-Shape Parameters
1.
Area
The Bucao Watershed has a total area of 68,145.77 Ha. or
681,457,700 m² with an approximate basin length of 41,261.57 m.
and has an average width of 20,631.31 m. The perimeter has an
approximate length of 226,268 m. covering all the tributaries
downstream to Bucao River. The river is drained downstream from
the foot slopes of Zambales mountain range converging down to
the central portion of the watershed.
The watershed is divided into five (5) sub-watersheds:
Pinatubo, Balintawak, Bucao II, Bucao I and Baquilan sub
watershed. Pinatubo Sub-watershed has the largest area covering
23,202.31 hectares followed by Balintawak Sub-watershed with an
area of 15,052.76 Ha. Bucao II Sub watershed has an area of
13,855.92 Ha. Bucao I Sub-watershed covers 9,903.40 Ha.
Baquilan sub watershed has the smallest area covering only
6,131.38 Ha.
Table 2. Watershed shape parameters
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2. Gravelius Form Factor
Gravelius form factor = Gf = Average width
Axial length of basin
Gf = 20,631.31
41,261.57
Gravelius form factor = 0.50
3. Bifurcation ratio
Table 3. Stream Order of the Five Sub Watersheds of Bucao
Ave. Br. = 13.85 + 19.85 + 11.82 + 20.88 +70.07
5
Ave. Br. = 27.29
The average Bifurcation Ratio of the five sub watershed is
the BR of the whole Bucao Watershed which is equal to 27.29.
Since the ratio is high, the discharge is low but with broad peak
which favors the use of the river as irrigation by the farmers.
13
Figure 6 Stream Order Map
14
4. Elongation Ratio
Elongation ratio
Maximum Basin Length (MBL) = 41,261.5655
Area of Watershed (Aw)
= 681,457,700 sq.mts.
Area of a Circle Ac= π (r2)
r2 = 681,457,700 m2
3.1416
_____________
= √216, 94,215.7
r2 = 14,728.00
Diameter (Dm) = 2r
= 2 x 14,728.00
= 29,456.06 mts.
ER = DM
MBL
ER = 0.714
Circulatory ratio (compactness coefficient)
Circulatory ratio = DM (π) / P
= 29,456.06 (3.1416) / 22,626.80
= 92539.1581/226,268
Circulatory ratio
= 0.409
15
5. Basin length.
The shape of the watershed is irregularly elongated with a
ridge protruding towards the mountain. Its headwater is located at
Mt. Pinatubo draining towards South China Sea. The drainage
pattern is characterized as sub-parallel dentritic.
B.
Watershed-Relief Features
1. Relief ratio = highest point – lowest point
Maximum basin length
=
1740 – 16
41,261.5655
Relief ratio
= 0.04
2. Relative relief = highest elevation
Perimeter of the basin
=
1740
226,268
Relative relief =
0.008
3. Elevation
Highest elevation – 1740 m
Lowest elevation – 16 m
16
4. Slope
Table 4. Slope categories of Bucao Watershed
Based on the above table, about 3.80 percent of the
watershed area covering an area of 2,588.24 Ha is flat or level to
gently sloping while 1.6 percent corresponding to 1,085.44 Ha is
moderate and about 94.6 percent equivalent to 64,472.09 Ha is
steep to severely steep.
17
Figure 7 Slope Map
18
The degree and severity of erosion and loss of fertility and
biological deterioration is directly and highly correlated to slope
gradient. The slope map (Figure 7) presents the prevailing
steepness of the terrain of Bucao Watershed.
C.
Channel Morphology
The drainage pattern of the watershed is sub parallel
dendritic. The main river system of Bucao River are the Maraunot
River emanating from Mount Pinatubo, Balinbaquero, Cabatuan
and Baquilan River converging at the middle portion of the
watershed area moving down to South China Sea.
D.
Drainage Texture
1. Drainage density
Dd = L = Total length of stream
A
area of watershed
Dd
= 1185255.92
68,145.77
Dd
= 17.39
2. Drainage/stream density.
DS = N = number of streams
A
area of watershed
DS
=
1,013
68,145.77
DS
=
0.0149
19
3. Length of overland flow
Fl
=
F
l=
FI
=
1
2Dd
___1___
2(0.0149)
33.56
Low Flow Discharge = 462.80 cu.m/sec.
High Flow Discharge = 646 .49 cu.m./sec
The width of the Bucao River varies from 15-25 kilometers
so the water is spread within the widest range before concentrating
and converging to the center of the watershed and directly drains
towards the South China Sea (Figure 8).
20
Figure 8 Drainage Map
21
2.1.3 GEOLOGY
2.1.3.1
GEOLOGIC COMPOSITION
The mountains and hills in the eastern, northern and
southern
portion
of
Bucao
River
are
mostly
Quarternary
Plyroclastics (Pyroclastics deposits; agglomerated and volcanic
ashes .Topographically, these rocks from prominent peaks, namely,
Mt. Pinatubo and Mt. Gatas to the east and Mt. Manquirat and Mt.
Iba to the north, while Mt. Culianan and Mt. Cawayen to the south
are under laid by undifferentiated volcanics largely composed of
metamorphosed andesitic to dacitic volcanic flows.
These are
intruded by andesitic abd dacitic quarternary plugs.
To the
northeast leading to Mt. Pinatubo are quarternary pyroclastic
consisting of pumice-bearing agglomerates, lava and ash flow
sequences (Javelosa 1985).
Based on geologic map, the general geological composition
of Bucao Watershed is dominated by mountain soils with entisols,
inceptisols, ultisols and alfisols with thermic hyperthermic and
isohyperthermic temperature regimes.
Table 5 Bucao watershed Soil Morphology
22
Figure 9 Soil Morphology Map
23
2.1.3.2 Formation and Age
On the southwestern foothills of Zambales range is consists
of lower conglomerate formation and the upper formation
composed of massive coralline limestone with siltstone and shale
interbeds. The age of the formation is Middle to Late Miocene
2.1.3.2 Geohazards Areas and Seismicity
There are potential earthquake generators identified in the
watershed. These are the Manila Trench, Mt. Pinatubo and several
active and potentially active fault systems that transect the area
(Umbal 1997). The fault systems consist of Iba Fault, East
Zambales Fault, San Antonio Fracture Zone and the Subic Bay
Fault (Figure 10).
2.1.3.4 Geological Feature (in relation to soil & water)
The groundwater in the province of Zambales occurs within
the interstices of Tertiary sediments, Quaternary volcanic and
recent alluvium (Figure 11). However, only the recent alluvium is
potentially high for large scale groundwater development.
The
main aquifers are sand and gravel horizons with varying degree of
permeability.
The deposit includes the unconsolidated to semi-
consolidated gravel, sand, silt, clay and occasional boulders, which
remains in floodplains, alluvial fan, terrace, former river channels
and beach deposits.
The Quaternary volcanic is dominated by
agglomerate, volcanics ash and cinders.
The area is limited in
groundwater flow, which is predominantly confined to fractures or
secondary permeability. The Middle to Late Miocene deposits
24
show the aquifers in these formations include the sandstone and
conglomerate with shale as the confining beds. These formations
generally show low permeability values. As a result, the aquifers in
these units are classified poor. In addition, saline water intrusion
commonly occurs in the coastal aquifers.
25
Figure 10 Seismicity Map
26
Figure 11 Geologic Map
2.1.4
27
2.1.4 SOIL
There are about nine (9) different types of soil that are
present in Bucao Watershed that greatly affects the productivity of
the watershed area (Figure 12). The characteristic features of
which are based on texture, structure, bulk density, permeability,
erosion condition, soil fertility and soil depth. The identified soil type
description of Bucao Watershed are Villar sandy loam, Tarlac soils,
mountain soils, Cabangan, clay loam, Beach sand, Bancal clay,
Antipolo clay, Angeles sand and Angeles Fine Sand. However, due
to the recent eruption of Mt. Pinatubo the watershed area is now
mostly covered with sand and lahar worsening the erosion
condition from moderate to severe.
A. Soil texture
Major soil types found within the Bucao Watershed
comprises the following types of soil. Mountain soil textured as
“undifferentiated”, Antipolo clay textured as “clay”, Angeles Fine
Sand textured as “Sand”, Villar sandy loam textured as “Sandy
Loam” and the last soil type Lahar textured as “Sand”.
Below are geometric characteristics regarding the various sizes
according to texture size.
Clay- less than 0.002 mm in diameter
Silt- greater than 0.0002 mm but less than (0.05 mm)
Sand- greater than 0.05 but less than 200 mm
28
B. Soil fertility
Soil fertility refers to the ability of the soil to support plant
growth and produce desired products in a given area. Table below
describes the pH level, nitrogen, potassium phosphate and total
organic matter contents of soil samples taken in the highest
elevation of the watershed at So. Malamio, Maguisguis, Botolan,
Zambales; middle elevation of So. Baukok, Baquilan, Botolan,
Zambales and the lowest elevation of So. Bucao, Porac, Botolan,
Zambales.
Based on the laboratory analysis report, the soil sample
taken for the low elevation has a pH value of 7.8 which is alkaline,
phosphate of 2.2 ppm, potassium 83 ppm and organic matter
content of 0.92 %. The soil sample taken from the middle elevation
of the watershed has a pH value of 7.5 which is also alkaline in
nature; phosphate of 8.0 ppm, potassium content of 210 ppm and
organic matter content of 0.97 % while the soil sample representing
the highest elevation of Bucao watershed has a pH value of 5.9
which is acidic, phosphate of 8.0 ppm; potassium content of 130
ppm and organic matter content of 60%.
For plantation establishment using forest and fruit bearing
tree species in low and high elevation of the watershed, the Soil
Laboratory of the Department of Agriculture recommends the
fertilizer application of 15 grams of 16-20-0 per tree and 21.3 grams
of 45-0-0 per tree during planting to be applied 3 to 4 inches away
from the seedling with a soil depth of 3 inches.
For plantation establishment of the same species in the
middle elevation of the watershed, the DA recommends fertilizer
application of 20 grams of 6-20-0 per tree and 20 grams of 45-0-0
29
per tree during planting to be applied 3 to 4 inches away from the
side with a soil depth of 3 inches.
They recommend also applying 4 kilos organic fertilizer per
tree in lowland, middle and upper elevation of Bucao watershed.
Table 6 Soil Analysis Result on samples taken in Bucao
Watershed
30
Table 7 Different soil types present in Bucao Watershed with
their respective characteristics
31
Figure 12 Soil Map
32
C.
Soil Depth
Based on the soil morphological characteristics 48,423.89
hectares or about 71.05% of the Bucao Watershed area is
composed of mountain soils with antisols, inceptisols, ultisols and
alfisols with thermic hyperthermic and isohyperthermic temperature
regimes found mostly in the mountainous areas of the watershed
about 17,061.63 or roughly 25.03 % of the watershed is made up of
tropopsamments with troporthents distributed evenly in all parts of
the watersheds particularly suited for agricultural purposes. The
remaining 2,660.25 hectares representing 3.90% of the total area of
the watershed is composed of entropepts with dystropepts,
tropudults with tropudalfs tropepts & oxisols.
2.1.5 LAND CLASSIFICATION/LEGAL STATUS OF LAND
The Bucao Watershed has an approximate area of
68,145.77 hectares broken down into 2 major land classifications
wherein 26.6 % (18,142.86) of which is Alienable and Disposable
Land and 73.4 % (50,002.91) is Forestlands. Based on FR 122
Presidential Proclamation No. 248 dated January 19, 1956, the
area forms part of the Southern Zambales Reserve (Figure 14).
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Percentage of Land Classification
within Bucao Watershed
26.60%
73.40%
Alienable & Disposable
Land
Forestland
Figure 13 Land Classification
Table 8 Status of Land of Bucao Watershed within the seven
(7) Municipalities and Two (2) Provinces
34
Figure 14 Land Classification Map
35
2.1.6 LAND CAPABILITY
The Bucao Watershed is comprised of Five (5) Major Sub
watersheds. It is briefly described as follows:
Table 9 Bucao Sub watershed
a. Bucao I Subwatershed
It covers an approximate area of 9,903.40 Ha. The
Timberland portion is presently utilized as part of the Bucao
Reforestation Project. It has been planted with a combination of
exotic and endemic forest tree species such as Teak, Narra,
and Mahogany, Agoho, Eucalyptus, Acacia auriculiformis,
Acacia pera and Acacia mangium. Other parts of this
Watershed have been devoted to upland agriculture mostly by
Aeta minorities. Cattle raising is also observed within this sub
watershed and likewise there are mining claims was observed in
the area.
b. Bucao II Sub Watershed
It covers an approximate area of 13,855,92 Ha. representing
20.33 % of the total watershed area. Patches of upland farming
were observed scattered within this subwatershed under the
36
Integrated Social Forestry Program presently covered with
CADC.
There are some tenurial instruments that have been issued
by the DENR within the area. These are CBFM, CCFS and
CADC. People living in the area are mostly aetas. Root crops,
banana blossom and vegetables are the main source of income
of the people.
c. Baquilan Subwatershed
It covers an approximate area of 6,131.38 Ha. or equivalent
to 9% of the total land area of Bucao Watershed. Some tenurial
instruments have been issued in the area namely: CBFM,
CCFS, FLGLA, SIFMA, IFMA and CADC. Portion of the CADC
area has been subjected to MOA with Botolan Reforestation Inc.
for developmental purposes. Presently their plantation is ready
for harvesting, however it is temporarily held in abeyance
pending compliance for some instructions stipulated under
E.O.23 and other related issuances, laws and regulations.
d. Pinatubo Sub watershed
This sub watershed is the largest among the five (5) sub
watersheds having an area of 25,202.31 Ha. or equivalent to
34.05 % of the total area of Bucao Watershed. Geographically
considered, the Mt. Pinatubo is found in the area. Residents in
this area are dominantly engaged with planting of Agricultural
crops such as vegetables, root crops and banana blossom.
37
e. Balintawak Subwatershed
It covers an approximate area of 68,145.77 Ha. or equivalent
to 22.09% of the total area of Bucao Wareshed. There are
13,417.47 Ha. or 19.67 % of the total land area are under the
Province of Tarlac specifically falls within the Municipality of
Capas and San Jose Likewise, there are Certificate of
Stewardship Contracts (CSCs) issued under Integrated Social
Forestry Project. Agriculture is the main source of the residents
therein. Other portion of the area is covered with the IFMA area
issued to AWECA. The holder has duly develop the area with
Gmelina and other fast growing species.
2.1.7 LAND USE
2.1.7.1
On Forest Lands/Upland Areas
Based on the orientation of the based map of Bucao
Watershed, some upland areas within the watershed are devoted to
upland agriculture. Depending on the legal and regulatory status
per specific area within the watershed. The land utilization relies
much on the capacity and privilege offered by tenurial instruments
and/or documents issued by the DENR. For instance, areas
covered by the Integrated Social Forestry Program such as the
CCFS and the CSC areas are devoted to upland farming or upland
agriculture. Open areas are likewise utilized for the same land use.
These areas are plantable mostly cash crops/ subsistence crops.
Portion of the Bucao Watershed are regulatory land use
areas (AFFLA, Adopt –A-Mountain, CBFM, CADC, FLGLA/FLGMA,
IFMA). These areas are principally devoted to upland development
particularly the establishment of tree plantation.
38
There are three (3) permanent resettlement site/ area
covered by the watershed. These are the Baquilan and Loobbunga
Resettlement Sites covering an area of 317.6 hectares and
257.31Ha. respectively and established on October 30, 1992 after
the Mt. Pinatubo eruption through the management of then MT.
PINATUBO
COMMISSION
with
cooperation
of
National
governments, LGUs, OGAs and NGOs.
The other is Bucao Resettlement site. This was identified
and established for the flood victims affected by typhoons Ondoy
and Kiko. This site was identified and established on October 4
2009 covering an area of 10 Ha.
Baquilan River downwards to barangay San Juan, Botolan is
adjacent Riceland Barangays.
2.1.7.2
On Alienable/Lowland Areas
Generally, all alienable lands (lowlands) inside the Bucao
Watershed have already been over laden with lahar deposits,
particularly to those areas adjacent to the Bucao River. Continuous
down flow of lahar from the upper slopes of Mt. Pinatubo is
observed every year most especially during rainy season. Lowland
areas nearby the Bucao River are always threatened by lahar flow
and submerged by water.
39
LAND USE CATEGORY
1. Built up Areas
a. So. Baquilan , So. Bucao and So. Loobbunga
These sites are located within barangay San Juan and Porac
Botolan, Zambales and falls within timberland block per LC no.645.
These three (3) sitios serves as the residential abode for the
affected populace of the recent Mt. Pinatubo eruption and lahar
flows and floods. A special land use permit and MOA were duly
signed and awarded to affected landless families as proof of
occupancy.
b. Barangay Bihawo
Occupied mostly by aeta minorities under LAKAS group.
This site is partly Timberland located at Barangay Bihawo, Botolan,
Zambales
2. Barren Land
Some areas within the watershed and vicinities thereof are
considered barren.
3. Lahar
Lahar area includes those areas along strams with
headwaters emanating from slopes of Mt. Pinatubo. The Bucao
River has been overlaid with lahar. This river is the main drainage
of Mt. Pinatubo down towards the Barangays San Juan, Carael,
paudpod, Batonlapoc, Porac, Paco, Beneg, San Miguel and
Bangan,Botolan, Zambales.
40
4. Inland
After the eruption of Mt. Pinatubo in 1991, the aftermath did
not only end on the amount of volcanic debris spewed by during
eruption but continued years after. As mentioned above, lahar has
devastated much of low lying areas along the Bucao River.
5. Fishpond
Residents of Barangay Carael, Botolan, Zambales have been
using fish pond as source of Tilapia and other fishes.
6. Agricultural Areas
Before the eruption of Mt. Pinatubo, the lowland areas of the
Bucao Watershed has been devoted mainly to rice production.
Large tract of agricultural land within these municipality have been
relying much on the availability of water supply emanating from
Bucao River
7. Forest
Man-made
forest
is
within
the
confines
of
Bucao
Reforestation Project planted by Administration and also through
contract reforestation and ISF projects. Though destroyed by the
Mt. Pinatubo eruption, some forest tree species have thrived well.
Natural forests are found within Bucao Watershed belonging to
second growth Dipterocarp forest and Molave type.
a. Production/Protection
Having been established as a reforestation project, the
Bucao Reforestation Project served as a protection of exotic forest
tree species has now been observed adjacent to previously
designated plantation block.
41
Natural forests belonging to Dipterocarp and Molave type
have been allocated to fall mainly on the protection category.
2.2.2 CLIMATE
Based on Coronas Classification the Bucao Watershed falls
under Climate Type I with two pronounced seasons. The dry
season covers the months of November to April while the rainy
season during the rest of the year with heavy rainfall during the
months of July and August. Figure 15 shows the Climate Map of
Bucao Watershed
42
Figure 15 Climatic Map
43
The rainfall data used for the Bucao Watershed was
obtained from the nearest Philippine Atmospheric, Geophysical
Astronomical Services Administration (PAGASA), DOST, Subic
Bay Weather Station, Subic Bay Freeport Zone, Olongapo City.
Based on ten year (CY 2000 to 2010) rainfall data shown in
Table 10 below the lowest average mean rainfall occurred in the
months of February with 5.9 millimeters while the mean highest
rainfall occurred in the months of July with an average of 808.3
millimeters for the past ten years (CY 2000 to 2010) with the
highest recorded rainfall in the month of July of 2002 with
2,195.2 millimeters.
Table 10 Monthly total amount of rainfall (mm)
44
Average Rainfall (2000-10)
900.00
Ave. Rainfall
(2000-10)
800.00
700.00
600.00
500.00
400.00
300.00
200.00
100.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 16 Average amount of rainfall
Table 11 Number of days with rainfall (mm)
45
Figure 17 Average numbers of days with rainfall
TEMPERATURE
The highest maximum temperature from CY 2000 to 2010
was during the months of April with an average of 40.68 degrees
centigrade and the minimum lowest average was in the months
of January with 21.85 degrees centigrade. Maximum
temperature ranges from 36.2 degrees centigrade to 38.2
degrees centigrade. Minimum temperature ranges from 17.9
degrees centigrade to 21 degrees centigrade with the lowest
recorded temperature in January of 2005 with 17.9 degrees
centigrade.
46
Table 12 Mean Temperature (2000-10)
Average Monthly Temperature
30.50
30.00
29.50
29.00
28.50
28.00
27.50
27.00
26.50
26.00
25.50
25.00
Average Temperature
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 18 Average Monthly Temperature
WIND
The average wind speed is 3 – 4 mps all throughout the
year with its prevailing direction of North East to South West.
47
RELATIVE HUMIDITY
Based on PAGASA readings for the period of CY 2000 to
2010, relative humidity ranges from 71.3% to 89% with the
mean annual relative humidity of 79.39%.
Table 13 Relative humidity in the watershed
Figure 19 Average Monthly Relative Humidity
48
2.2.3 HYDROLOGY
DRAINAGE PATTERN
Bucao watershed consists of five (5) sub watersheds
namely Bucao I, Bucao II, Bakilan, Pinatubo and Balintawak
Subwatersheds.
The head waters originates from the
Southeastern portion of Mt. Pinatubo and on the North eastern
portion from Mt. Cahapatan, Mt. Iba and Mt. Mangkirat going
down to the main outlet which is the South China Sea.
The drainage pattern of the watershed is sub-parallel
dendritic with several creeks that are irregularly transversing the
Five (5) subwatershed from the head water to the common
outlet.
The width of the river during minimum flow is 80 m and
the deepest part is 1.0 m in height from the bottom surface of
the river. The average water depth is 0.178 m and average
velocity of 32.5 m/sec.
During peak flow the width of Bucao Watershed is 124 m
and the deepest portion is 1.6 m in height from the bottom
surface of the river. Average water depth during peak flow is
0.80 m.
STREAM FLOW RATE
The computed water discharge during low flow is 462.8
cubic meters per second. While the peak flow discharge is
646.49 m³/sec
STREAM FLOW QUANTITY/ QUALITY
Based on the results of water analysis of Bucao
Watershed, average pH is 7.6 which means that the water is
alkaline. pH is an important water quality parameter because the
solubility of minerals and metals in water are affected by the
changes in pH. The survival of aquatic organisms diminishes as
49
pH falls below 5 or increases .above. A pH of 6.5-8.5 is ideal for
most water uses.
The total coliform and fecal coliform in the river exceeds
the limit of 1,000 MPN/100 mL and 200 MPN/100 mL
respectively. Water with fecal coliform is considered unsafe for
swimming. Coliform bacteria grow in the digestive tracts of
humans and serve as indicators of fecal contamination and as
marker for other pathogenic microorganisms.
Same case goes through phosphate results which are
higher than 0.2 standards. The presence of excess phosphate
ion affects aquatic ecology because it over fertilize plants.
The Biological Oxygen Demand (BOD) of Bucao River
ranges from 8-16 mg/L. BOD is a chemical procedure for
determining how fast biological organisms use up oxygen on a
body of water. It is also widely used to determine the pollution
strength of domestic and industrial wastes.
2.2.4 INFRASTRUCTURE
Report of the Municipal Planning and Development
Coordinator shows that major roads and bridges has been the
immediate projects of the LGU, especially after the eruption of
Mt. Pinatubo where many roads and bridges were completely
devastated.
Construction of the Bucao Bridge has been completed,
concreting of Taugtog-Loob-bunga bridge, farm to market roads
to other barangay has been completed but construction of farm
to market roads going to eastern barangays is still not possible
due to lahar deposit.
50
The construction of Botolan-Tarlac National Road is one of the
major project that is being looked into by the LGU.
Elementary schools have been constructed since most of
the residents of the eastern barangays are moving back with the
stabling condition o\f the areas affected by the eruption.
Generally buildings and houses are constructed at the
resettlement areas of Baquilan and Loob-bunga, and along the
higher grounds of the Bucao River.
Elementary and High School buildings were already
constructed at Sta. Fe, San Marcelino, Zambales.
Concrete hanging bridge is also built at So. Tangan
tangan, Maamot, San Jose, Tarlac
2.2
BIOLOGICAL RESOURCES
2.2.1 VEGETATION
The vegetation of Bucao Watershed is composed of five
(5) Classes, open brushed leaved forest, other wooded land
shrubs, other land natural grassland, closed forest broad leaved
and other land cultivated annual/perennial crops.
Generally,
large portion f the watershed area is covered by open forest
broad leaved and other land cultivated annual/perennial crops.
Closed forest broadleaved covers more o less 1,786.28
hectares or 2.62% of the watershed area located within the
boundaries of Tarlac & Zambales.
Natural grassland composed of grasses and shrubs with
scattered patches of trees and other minor forest products are
found visible along river systems and channels.
While the
remaining patches of the forests are dominated by alibangbang,
binayuyo. Akleng parang and other trees in natural stand
51
observed along the southern and northern portions of the
watershed areas.
Table 14 Forest Cover of Bucao Watershed
Table 15 shows that there are 44 trees species identified thriving
in the watershed area which is distinctly dominated by lesser
known species such as Binayuyo, Akleng parang and Anabiong.
Also prevalent in the area are natural stand of Palosapis,
Apitong and Lauan dipterocarp species found along the
remaining portion of the close forest broad leaved forest cover of
the watershed. Consequently, the remaining species are more
or less evenly distributed all along the whole watershed
exhibiting the species diversity of Bucao Watershed.
52
Table 15 List of Flora within Bucao Watershed
53
2.2.2 FAUNA
LIST OF FAUNA INVENTORIED WITHIN BUCAO WATERSHED
Table16 Species Diversity Using Shannon Weiner Index
54
Per physical inventory and assessment of existing fauna
in twenty three (23) sampling plots of Bucao Watershed
measuring 20 meters wide and 20 meters long there were
thirteen (13) birds species, five (5) species of reptiles, six (6)
species of mammals, two (2) amphibians and sixteen species of
insects recorded.
Out of the thirteen (13) species of birds Martinez is the
most prevalent both in number and occurrences. Moreover, the
snake and wild pig are the most commonly seen reptiles and
mammals in Bucao Watershed.
The parameters in analyzing the status of the faunal
community for the diversity index was calculated from both the
species richness and abundance by applying the Shannon index
indicator system. The value of the Shannon was rated based on
the bio-diversity survey guide.
55
2.3
SOCIO-ECONOMIC SURVEY AND DEMOGRAPHY
2.3.1
POPULATION AND DENSITY
The Bucao Watershed has a total population of 62,579 as
of 2010 NSO Census. In Zambales side, the total population is
61,963 with Barangay Villar as the most populated Barangay
having a total of 22,822 and Barangay Balincaguing as the least
with zero individual representation
Likewise, in Tarlac side that is covered by the watershed
the total population is 616 with Barangay Maamot as the most
populated having 404 individuals and Barangay Sta. Juliana as
the least with a population of only 212 individuals.
In Zambales, the population growth rate is 1.86 percent
while in Tarlac side is 1.47 percent. The populations of
Barangays within 7 municipalities in Bucao Watershed are
distributed as follows:
Table 17 Population density
56
2010 Population/Area by Municipality
within Bucao Watershed Area
70,000
Population
Area (Ha.)
60,000
50,000
40,000
30,000
20,000
10,000
-
Botolan
Cabangan
San
Marcelino
Iba
San
Felipe
Capas
San Jose
Figure 20 Population density by Municipality
2.3.2 AGE AND SEX STRUCTURE
In Zambales which comprises five (5) municipalities
namely Iba, Botolan, Cabangan, San Felipe and San Marcelino,
79 .10 percent of the population belongs to labor force with an
age bracket of 15 years old and above and 20.90 percent age
bracket belongs to younger group or non working group.
In Tarlac side which comprises only two (2)municipalities
namely San Jose and Capas, 79.38 percent belongs to 15 years
old and above bracket representing the working group, while
20.62 percent are non-working group with age belongs to 14
years old and below bracket.
With regards to gender, the population within the Bucao
River Watershed is dominated by females by only 1.008 percent
over the males. In Zambales side, 50.432 percent are females
and 50.005 percent are males. Likewise in Tarlac side, the
percentage of males and females did not vary with that of
Zambales.
57
The average Annual Growth Rate of Zambales side is
1.86 percent while in Tarlac side is 1.47 %.
Table18 Population data of Bucao Watershed segregated by
Gender
Figure 21 Population/Gender by Municipality
58
Figure 22 Municipality of Botolan Age group
Figure 23 Municipality of Cabangan Age group
59
Figure 24 Municipality of San Marcelino Age group
Figure 25 Municipality of Iba Age group
60
Figure 26 Municipality of Capas Age group
Figure 24 Municipality of Capas Age group
Figure 27 Municipality of San Jose Age group
61
2.3.3 HOUSEHOLD/ FAMILY SIZE
Data gathered from the five (5) municipalities of
Zambales and two (2) municipalities of Tarlac which are covered
by the Bucao Watershed shows that the average household size
is 4-5 members and majority of the households is having a
maximum of 6 and minimum of 3 children in the family.
2.3.4 LIVELIHOOD AND INCOME/ PROFILE/ SOURCES
Based on the existing land area of Bucao Watershed,
22,140.46 hectares is devoted to agriculture. Out of the total
area, 2,762.83 hectares is irrigated and 19,377.63 hectares is
unirrigated tilled by low land farmers. While the upland areas is
1,720.38 hectares being occupied by upland farmers who are
members of CBFM Projects.
Rice crops dominate most of the areas devoted to
agricultural production. Most are in low land area, which are
planted with hybrid and in-breed rice both in irrigated and rain
fed areas. Large portion of rice land is irrigable due to
rehabilitated NIA irrigation system. However, Production is still
low due to non-fertile soil problem, uncontrolled natural
calamities (Typhoon) pest and diseases.
Farmers also produced other crops like corn, different
vegetables and root crops and fruit bearing trees as unirrigated
areas.
Farming, fishing and livestock production are the major
source of livelihood within the watershed area. The annual
income ranges from Php 36,000.00 to Php 72,000.00 Upland
dwellers who are mostly benefeciaries of the CBFM program
derived their income from planted fruit bearing trees and other
agricultural crops such as palay, vegetables, corn, root crops
etc. The communities within the watershed generally has no
62
enough financial earnings in term of savings because their
income is just enough for daily subsistence.
2.3.5 SECTORAL PRODUCTION
Majority of the residents within Bucao Watershed are
engaged in farming, fishing livestock & poultry production. Rice
crops, different kinds of fish and cattles like cows and carabaos
are the major products. Other crops of economic importance are
corn, bananas, vegetables and root crops such as cassava, gabi
and camote. Likewise fruit bearing trees such as mango,
cashew and coconut are additional products that derived from
the watershed areas.
2.3.6 EMPLOYMENT PATTERN AND PROJECTION
The municipalities of Iba, Botolan, Cabangan, San Felipe
and San Marcelino all in Zambales and San Jose and Capas in
Tarlac have more than one-half of its total population in the labor
force, yet unemployment is still a problem. Due to limited
employment opportunities, majority of those in the labor force,
even professionals, eligibles, competent and had even met the
minimum qualification standard are doing manual jobs and
accepting contractual job orders just to earn money for their
daily subsistence. Those who landed as job order workers are
force to accept salaries way beyond the minimum basic salary
just to augment their family needs and for self-survival.
Domestic as well as overseas employment is also minimal due
to limited opportunities and financial incapacities.
63
2.3.7 SOCIAL, EDUCATIONAL AND MEDICAL SERVICES
With regards to health, nutrition and medical services,
these are being delivered by a resident midwife and nurse from
the Municipal Health Offices with the assistance of Barangay
Health Workers assigned in every Barangay Health Center/
Station. In case of serious illness, patients are brought and are
treated at the Provincial Hospital located at Iba, Zambales and
other private hospitals in Zambales, Olongapo and Pangasinan.
2.3.8 TRANSPORTATION AND COMMUNICATION
The violent eruption of Mt. Pinatubo on June 15, 1991
ranks as one of the largest volcanic events of this century, has
left an indelible imprint in the lives of many residents within the
Bucao watershed. Several Barangays at the eastern part of the
watershed were buried deep of volcanic ash and lahar including
Barangay roads and bridges leading to eastern part of
watershed area. The Bucao river and other tributaries were
silted with lahar and volcanic deposits. Now only weapon carrier
and carabao cart are the only means of transportation of people
residing on the central and remote barangays of the watershed
area.
Some residents owned radios, televisions, CD and DVD
player from which they obtain both news information and
entertainment. Likewise cell phones are the common means of
communication everywhere in the locality.
2.3.9 TOURISM AND RECREATION
Based on the Socio-Economic Profile gathered from the
five municipalities of Zambales and the two(2)municipalities of
Tarlac, there are no potential areas for eco-tourism within the
watershed area except the crater of Mount Pinatubo which serve
as research purposes and recreation of foreign and local
visitors.
64
2.3.10 RELIGIOUS
SECTORS,
POLITICAL
AND
SOCIAL
ORGANIZATION
2.3.10.1 Cooperative/ NGO’s / Social Organization
Permanent residents within the Bucao Watershed consist
of several associations/ organizations. Upland farmers formed
their People’s Organization under CBFM project of the DENR
while lowland farmers formed their Irrigators Association under
National Irrigation Administration (NIA) and cooperatives being
assisted by the local Department of Trade and Industry (DTI).
2.3.10.2 Religion
Roman Catholic is still the dominant religious affiliation of
residents within the watershed area. Other religions are
Aglipayan, Protestant and Iglesia ni Kristo that are well
established in the area.
2.3.10.3 Political
Bucao Watershed which covers the municipalities of Iba,
Botolan, Cabangan, San Felipe and San Marcelino, Zambales
belongs to the Second District of the Province of Zambales
under Hon. Congressman Antonio M. Diaz (deceased) while
municipalities of San Jose belongs to the Second District of the
Province of Tarlac under Congresswoman Susan A. Yap and
Capas which belongs to the Third District of the Province of
Tarlac under Congresswoman Jeci A. Lapus.
Under the political structure of present government,
electoral process of the government either local or national is
being held within the Barangays inside the watershed area
designated by the Commission on Election.
65
It was also observed that aside from the elected
Barangay Captains in every Barangay, there are Chieftains who
head a clan of minorities particularly the original aetas.
Other institutions exercising some form of leadership in
the area are the Parents Teachers Association (PTA) and active
Chapel leaders who take charge and responsible of the
Festivities and other forms of community endeavors.
2.3.10.4 Citizen Participation
Residents in the community within the watershed
exercised fully their rights to vote during election and very active
in attending meetings, public forum and other community
assemblies conducted by different government organizations
especially when it regards to the provision of basic services,
livelihood, government programs and projects and other related
services for the welfare of the community as whole.
2.3.10.5 Ancestral Domain Claims
Certificate of Ancestral Domain Claims (CADC) issued
within the Bucao watershed are located at So. Maporac, New
San Juan, Cabangan, Zambales covering an aggregate area of
6,203.0 hectares issued in 1995. Other CADC areas are located
at Barangay Poonbato and Villar, Botolan, Zambales covering
an area of 8,700.0 and 22,400.0 hectares both issued in 1996
respectively.
Source: Official record kept on file by CENRO, Botolan, Zambales
2.3.11 BEHAVIORAL AND CULTURAL PATTERNS
There are three (3) ethnic groups found within the
watershed area. These are the Ilocanos, Tagalog and
Zambaleňos.
Other
ethnic
groups
are
Pangasinenses,
Pampagueňos, Visayans, Bicolanos and some Muslims. Major
66
dialects
spoken
are
Ilocano,
Tagalog,
Zambal
and
Pangasinense.
Residents within the Bucao watershed considered Bucao
River as their source of living since irrigation for all the
agricultural lands within the watershed depends in this river
that’s why occupants are very concerned with the protection and
conservation of the watershed to ensure the continuous supply
of water for their agricultural farms.
With regards to the culture of the occupants within the
watershed are noted of their respects for the olds and allegiance
to their clan. Women are regarded the traditional way as
housekeeper. However it was observed that some women are
assisting their husband working in the field especially in the
developmental activities of their respective farm lots within the
Community-Based Forest Management areas. Children on the
other hand are noted of their usual respect to their parents and
assist simple works in the household chores especially during
school vacation.
Superstitious belief is prevalent in almost all the
Barangays within the watershed area. Primitive religiosity like
belief in bad spirits and supernatural are still active. Many
superstitious belief cannot be denied that until this time many
occupants are giving more emphasis and importance.
In general, residents within the Bucao watersheds are
hardworking, self reliance and diligent to earn for their daily
living. They kept themselves always busy and they don’t waste
time for unproductive undertaking.
67
III.
VULNERABILITY ASSESSMENT
METHODOLOGY IN VULNERABILITY ASSESSMENT AND
HAZARD ANALYSIS
3.1
Formation of Multi-disciplinary team and Site Selection:
A
multi-disciplinary
team
coming
from
various
sectors/services of DENR was created through a Special Order
signed by the Regional Executive Director. Leveling workshop
with the regional team was then conducted to understand the
concept of vulnerability assessment as well as delineate
responsibilities for the joint research undertaking.
3.2
Gathering/Updating of Primary and Secondary Data
This involved the gathering of secondary and primary
data on various watershed characteristics. Assessments
include the following:
3.2a. Bio-physical Assessment
1)
Watershed
morphology (area,
elevation,
slope,
drainage
pattern/density)
2)
Geology and soils (geologic materials and arrangement, fault
lines, soil physical and chemical properties)
3)
Climate
(annual/monthly
rainfall,
evaporation,
typhoon
occurrence and frequency, etc.)
4)
Land use/vegetation (vegetation and extent of area). Land use
mapping with the use of Landsat/spot images was employed
coupled with field check and onsite verification on some land
uses.
5)
Hydrology (streamflow, water quality, flood and drought
occurrence). Water samples were taken at different times of the
year and analyzed for various water quality parameters
(temperature, pH, dissolved oxygen, conductivity, alkalinity,
etc.).
68
Gathered information were translated into thematic maps
and/or
tables
or
graphs.
Field
validation
included
the
determination of the maximum flood level and landslide
characteristics (location, size, aspect, soil/geology, slope and
land cover).
3.2b Socio-economic Assessment
Data on socio-demography (sex, age, income, education,
etc.) was gathered through interviews. Assessment also
included the
determination
of
attitudes,
awareness
and
perceptions of watershed occupants including existing programs
in the area that may aggravate or reduce the vulnerability of the
watershed to certain hazards. Map on the location of critical
facilities,
i.e.
schools,
roads
and
bridges,
hospitals,
floodplain/riverbank houses and other critical structures was
also made.
3.3
Hazard Identification, Critical Factor Analysis and Mapping
Hazards occurring in the watershed both upstream and
downstream portions were identified from characterization data
and site visits. Focus of hazard identification includes flood,
landslide/erosion, fire, pollution, deforestation/encroachment
and biodiversity loss. Hazard information from MGB, PHILVOCs,
PAGASA and other agencies were sourced out also.
Hazards and its contributory factors were determined
through analysis of watershed characterization data and through
the conduct of focus group discussions (FGD) with occupants of
the watershed and other key informants. Specific sites where
the hazards occurred were put in the map during the field
69
surveys. A crucial element in reducing vulnerability to natural
hazards is the analysis of human settlements and infrastructures
as gathered in activity 1b.
The methodology formulated by ERDB was followed
wherein
natural
forces
and
anthropogenic
factors
recognized as factors affecting the vulnerability of
were
the
watersheds to hazards. In the case of landslide for example, two
major factors were considered to influence its occurrence.
These are: bio-physical factors that include rainfall, land use or
vegetation, slope and terrain, geology/lithology, distance from
fault line, soil morphology, road and river cut; and Anthropogenic
factors like access/property rights, farming practices and ground
disturbance. In the case of fire, the two major factors considered
include: biological factors such as dry fuel materials, vegetation,
slope and terrain, aspect in relation to wind and exposure, wind
velocity and direction, dry spell, firebreaks, natural barriers,
proximity to fire prone areas, accessibility and infrastructures;
and Anthropogenic factors like access/property rights, social
knit, leadership, incendiarism, awareness/knowledge, beliefs,
perceptions, attitudes, household/ community economy, markets
and prices, capital investment, technology, institutions and
policies. Each of the factors has a numerical score of 1 to 5,
and a total maximum value of 100 can be computed.
3.3.1 Landslide Assessment
For assessing landslide vulnerability due to bio-physical
factors, the various thematic maps were assigned class and
weights according to relative their importance in influencing
landslide. These are briefly discussed below.
a)
Slope
In order to make the assessment more systematic, all
slopes from 0-8% slope (level to gently sloping) where
70
categorized as areas of low vulnerability to landslides. Steep
slopes (>50%) where considered to be areas very high
vulnerable to landslide occurrence.
b)
Soil
One of the most known parameters to contribute to
occurrence of landslide is soil characteristics. In the absence of
detailed soil texture and hydraulic conductivity analysis a
general soil map based on soil classification can be used.
Young soils (inceptisols) were considered less susceptible to
landslide as compared to old soil (oxisol and ultisol).
c)
Rainfall
Rainfall is considered as the triggering factor to the
occurrence of landslide. In the absence of rainfall isohyet,
historical monthly average rainfall was used in assessing the
vulnerability of the watershed to landslide.
Rated monthly
average rainfall is shown in the Table 9 below.
d)
Typhoon Occurrence
As per modified Coronas Classification of PAGASA,
Botolan, Zambales area belongs to Climate type I characterized
by two pronounced season: dry from November to April and wet
during the rest of the year. Bucao area is rated medium to high
in terms of vulnerability to typhoon incidences.
e)
Land Use
Land use map derived from 2002 LANDSAT satellite
images were analyzed and validated in the field. The watershed
is dominated by Riceland, timber and forest land. Agricultural or
cultivated areas also cover considerable hectarage. Rating was
largely based on the presence and type of vegetation cover in
the watershed.
71
f)
Distance From Fault Line
Areas near fault line can be considered more weathered
and fractured as compared to areas farther from the fault line.
The watershed was found to be quite far from any fault line
hence this factor was considered not a significant in the
analysis.
g)
Geology/Lithology
Geologic map from Mines and Geosciences Bureau
(MGB) was utilized. Rating was inferred based on general rock
consolidation. That is, young sedimentary deposits are less
hardened compared to old sedimentary deposits. Likewise,
igneous rocks and intrusives are likely to be more hardened.
h)
Road Cut
Road cuts in steep slopes are known to induce
landslides. Unprotected road cuts will be more susceptible to
landslides. Road widening on very steep slopes naturally
produced steep road cuts.
3.3.2 Soil erosion assessment
Soil erosion is favored by high rainfall and intensive
hillyland agriculture in the humid factors. However, the
magnitude differs in time and space due to disparity in edaphic
and others factors. Scientific studies on soil erosion need
adequate funding and considerable time to generate reliable
results.
3.3.3
Flood Assessment
Flood is a natural and recurring event for a mriver or
stream resulting from heavy or
continuous precipitation
exceeding the absorptive capacity of soil and the flow capacity
72
of rivers streams, and coastal areas. Flood hazard assessment
based on direct measurements may not be possible, because
there is no basis to determine the specific flood levels and
recurrence intervals for given events.
3.3.4
Forest/Grass Fire assessment
Fire behavior model requires elevation, slope, aspect,
weather and vegetation to simulate fire behavior across the
landscape. In general, most fire behavior models require
estimates of the following variables in order to generate
predictions: total above-ground biomass contributing to the
forward rate-of-spread of the fire; mean stand height; fuel
particle surface-area-to-volume (SAV); and moisture content.
Acquiring these estimates can be very costly. As an initial
approach, the fire hazard factor was applied in the analysis.
"Hazard Factor" means the factors which most influence the
potential of a geographic area to burn. Hazard factors are
climate, topography, natural vegetative fuels, natural vegetative
fuel distribution and anthropogenic factors. In this study, forest
fire was considered to be highly affected by anthropogenic
factors and the assessment follows the model presented in
Annex Table 1.
3.3.5
Deforestation/Biodiversity Loss Assessment
Using an updated land use/land cover map of the
watershed under investigation, each land cover type shall be
characterized using the transect-square plot technique of plant
inventory. Series of sampling points shall be established where
the observation plots will be set up. Each observation plot shall
consist of two squares, the smaller nested within the larger.
Fauna survey is the sampling of fauna forms (birds,
mammals, herps, macro fungi and insects) shall be conducted
along the plots established by the vegetation survey group.
73
Systematic listing of observed faunal forms shall be conducted.
Also, secondary information on the presence of faunal forms
shall be gathered from local informants
74
Figure 28 Physical Flood Vulnerability Map
75
3.4
GIS and Spatial Analysis
Overlay and index method which involve combining
various watershed attributes (e.g., geology, soils, slope, climate,
land use, anthropogenic factors) was used. In this approach, all
attributes were assigned class (Class 1 – 5) and weights (1-100
%). This method was considered to be the simplest approach in
vulnerability assessment that can be adopted by the DENR
regional offices and is still favored by many researchers and
planning agencies in various countries. Overlay and index
method attempts to be more quantitative by assigning different
numerical scores and weights to the attributes in developing a
range of vulnerability classes which are then displayed in the
map.
Results of this activity include the spatial location of
vulnerable areas including their classification whether high to
low to various hazards (degree of vulnerability).
3.5
Formulation of Mitigating Measures
Series of Focus Group Discussions in the area as well as
workshops by the technical team and key persons were
conducted to come up with appropriate mitigating measures.
The mitigating measures focused on interventions that may
reduce the effects of the identified hazards or improve the
adaptation of the watershed to the identified hazard (s)
3.6
Review, Analysis and Policy Recommendation
Existing policy(s)
gathered during the conduct of
watershed characterization were reviewed and relevant national
policies were analyzed. Series of in-house workshops were
initiated by the Team to come up with the needed policy
recommendations to address the identified problems and
minimized damaged due to the identified hazards.
76
RESULTS AND DISCUSSION
A.
Hazards Identification
There had been much concern given how Bucao
Watershed behaved and reacted to impacts due to some
changes of land use or modification of its original landscape.
These impacts were empirically understand to be the physical
events resulting to loss of lives and properties especially in
places and times when they interact with human activities, these
were termed Hazards. There are two (2) kinds of hazards:
natural and man-made. The former are natural physical events
like flood, landslide, earthquake and volcanic eruption, while the
latter are those which result to a disaster having an element of
human intent like negligence, error or failure of a system. More
often than not, effects or disasters coming out from natural
hazards are aggravated by human involvement which happen in
the farm of lack of planning.
Hazards identified in Bucao watershed;
1.
2.
3.
4.
5.
B.
landslide
soil erosion
flooding
biodiversity loss
fire
GIS-Approach to Landslide Analysis
The strength of overlaying or evaluating factors that
contributes to the occurrence of landslides lies on the availability
and the details of various thematic maps. Every thematic map
has different weight and influencing factor towards the
development of landslides.
For each maps, relative weights
were assigned and rated by the team experts.
The final
mathematical model applied to derived the landslide vulnerability
map is:
77
Landslide Vulnerability Map = (Rated Slope Map x 0.30)+(Rated
Soil Map x 0.10)+(Rated Rainfall and
Typhoon
frequency
Map
x
0.20)+(Rated
Geologic
Map
x
0.15)+(Rated Land Cover Map x
0.20)+(Rated rock Fracturing/Fault line
x 0.05)
The derived GIS – assisted approach to landslide
assessment due to bio-physical factors was then applied to
Pinulot watershed together with the anthropogenic factors
contribution to come up with the model:
Landslide = 0.90 (biophysical factors)+(0.10 anthropogenic
factors)
The anthropogenic factor was determined by taking the mean of
factors considered to contribute to the vulnerability of the
watershed to landslide.
The rating used in the FGD’s were as follows (as indicated in the
instrument).
1 – Factors plays is Very Low Vulnerability
2 – Factors plays is Low Vulnerability
3 – Factors plays is Moderate Vulnerability
4 – Factors plays is High Vulnerability
5 – Factors plays is Very High Vulnerability
78
Figure 27 Landslide Final Vulnerability Map
79
C
Vulnerability assessment to Landslide
The derived GIS-
assisted approach to landslide
assessment due to physical factors was applied to Bucao
watershed and the anthropogenic factors were considered in the
FGD which covers items such as farming system, ground
disturbance by human activities and occupancy and habitations
as contribution to come up with results using the model and
computing its landslide rating which is:
LANDSLIDE = .90 (biophysical factors) + (0.10 anthropogenic
factors)
Level of Vulnerability through Biophysical Factor
The overlaying of the different factors like slope,soil,
rainfall and typhoon occurrence, geology, land cover and fault
were given weights to derive a vulnerability map of Bucao
watershed.
Bucao Watershed is considered as highly vulnerable to
landslide. This is because almost 91.45% of the total area is
within the 50> slopes. and is located within the mountainous
part of the area which is mostly wooded land and grassland
areas. During extreme typhoons, areas along the Bucao River
80
is affected by flooding. Riverbank erosion also affects the
riverside areas. The level of vulnerability of Bucao Watershed to
Landslide was rated as high vulnerability with a rating of 4.59.
Level of Vulnerability through anthropogenic factor
The Anthropogenic factor was determined by taking the
mean of the factors that affect landslide in the area. These are
farming systems, ground disturbance and occupancy and
habitation. These factors were rated and an average rating of
3.8 which are considered being moderate to highly vulnerable.
The
over-all
vulnerability
assessment
of
Bucao
Watershed to Landslide as reflected in the vulnerability map
(Figure --) covers about 57.32% of its total area of 68,145.77
hectares. The factors that highly contribute to landslide is due to
its slope of the area with almost 91.45% is within the 50> asl,
and also the excessive rainfall and its typhoon occurrence. The
eruption of the Mt Pinatubo has a great effect in the soil erosion
that brought the area and its tributary to be covered by
pyroclastic deposit, rivers and streams therefore leads to
overflow of water causing the lower part of the watershed to
flooding.
81
Table 19. Assessment of the Vulnerability of Bucao
Watershed to Landslide
LEGEND:
1 – Very Low Vulnerability (VLV)
2 – Low Vulnerability (LV)
3 – Moderate Vulnerability (MV)
4 – High Vulnerability (HV)
5 – Very High Vulnerability (VHV)
82
Table 20 Bucao Watershed Landuse
IV.
ANALYSES OF ENVIRONMENTAL ISSUES, PROBLEMS AND
OPPORTUNITIES
A. FOREST ECOSYSTEM
The Forest Ecosystem of the Bucao Watershed is
composed of Dipterocarps, Molave and miscellaneous species.
The presence of endemic species of flora and fauna are
presently threatened due to the destruction of national habitats
brought by the cutting of trees and charcoal making particularly
in areas subjected for mining operations/ extraction and
construction of Road-Right of Way. Continuous destruction of
habitat may lead the area for total depletion extinction of the
flora and fauna.
The continuous and improper extraction of mineral
resources, cutting of trees and charcoal making causes soil
degradation and leads the watershed decreases of water
supply.
83
B. UPLAND ECOSYSTEM
The upland ecosystem is composed of the existing forest
plantations, shrubs and miscellaneous species. These areas
also contain voluminous deposits and potential area for
developmental purposes.
These are areas within the Bucao Watershed that are
covered with tenurial instruments; these are the CADC, CBFM,
Co-management Agreements, Adopt-A-Mountain, Certificate of
Stewardship Contracts and Mining Leases (Small Scale and
MPSA).
There are also areas in the watershed categorized as
unproductive Alienable and Disposable (A&D) and agricultural
lands owned by private individuals. These areas are frequently
razed by forest fires particularly during dry seasons often
caused by carelessness, insendiarism and Kaingin making.
Implementation of prepared Forest Fire Management Plan in
these areas is very difficult due to insufficient water supply ,
rocky terrain and lahar. Residents and informal settlers within
the adjacent areas have lessened concerns with the protection
of the uplands. Hunters, tree cutters, charcoal and firewood
gatherer and Miners causes’ forest fires in the area.
Second growth forest is threatened by the illegal tree
cutters, charcoal makers and miners. These activities may
accelerate
deforestation,
soil
erosion
and
landslides.
Intervention of influential people in the community/ locality
causes failure in the forest protection campaign, development
and conservation efforts of the government. Information and
education campaign should be conducted to educate people
therein and strengthen their awareness on environmental and
forest protection.
84
C. GRASSLAND ECOSYSTEM
This area is composed of several shrubs, natural grasses
and cultivated areas with A &D lands. Productive agricultural
lands are found in the lowland. The presence of the irrigation
facilities is the most important support to the farmers to make
their areas productive.
Problems encountered in developing the areas are the
insufficient support to the farmers. Higher cost of farm inputs
and the lower price of their products keep most farmers on the
level behind poverty line. Government interventions like giving
support to the farmers in terms of lower price of seeds to be
planted and marketing of their products may help farmers to
uplift their economic status. They should be trained on the
marketing strategies and other livelihood project.
The
government should establish a ONE-STOP- SHOP to centralize
the marketing of their products and regulate the prevailing and
reasonable prices of the products.
The analyses of environmental issues, problems and
opportunities of the above ecosystems are based on the result
of the strengths, weaknesses, opportunities and threat (SWOT)
analysis of the watershed.
85
D. SWOT Analysis
86
SOCIO-ECONOMIC SURVEY /INTERVIEW
OF RESIDENTS WITHIN THE BUCAO
WATERSHED
87
FOREST ECOSYSTEM WITHIN BUCAO
WATERSHED
88
COORDINATION AT PENRO TARLAC WITH PENRO
ALCIDE B. AMADOR
89
Coordination at
CENRO Tarlac with CENRO
Laureano Macadangdang
Coordination with the Brgy. Capt. of Barangay
Maamot, San Jose, Tarlac
90
INFRASTRUCTURE FACILITIES WITHIN BUCAO
WATERSHED
91
ASSESSMENT OF BIODIVERSITY
Sampling plot no. 5 with coordinates of N 15.15’ and E 120.12’
So. Malamio,Brgy. Maguisguis, Botolan, Zambales
92
Natural spring located at So. Malamio, Brgy. Maguisguis, Botolan, Zambales
93
Establishment of sampling plot no. 8 with coordinates of N15˚09’ and E 120˚15’
So. Bongolan, Brgy. Moraza, Botolan, Zambales
Collection of soil sample at So. Bongolan, Brgy. Moraza, Botolan, Zambales
94
Establishment of sampling plot no. 7 with coordinates N 15.09’ and E 120.18’
So. Tarao, Brgy. Villar, Botolan, Zambales
95
Overview of sampling plot no. 11 with coordinates of N 15.12’ and E 120.12’
Mt. Culianan, Brgy. Burgos, Botolan, Zambales
96
FLORA
Sampling plot no. 12 with coordinates of N 15’21” and E 120’15”
Located at So. Mapalinday, Tangan-tangan, Brgy. Maamot, San Jose, Tarlac
Establishment of 20 x 20 sampling no. 12 So. Mapalinday, Brgy. Maamot,
San Jose, Tarlac
97
Identification of forest tree by For.II Jose L. Gelacio at So. Mapalinday,
Brgy. Maamot, San Jose, Tarlac
98
Sample plot no. 12 with coordinates of N 15’21” and E 120’15”
located at So. Mapalinday, Brgy. Maamot, San Jose, Tarlac
99
Photo shows some species of forest products found within plot no. 12
100
Tangile tree found at sample plot no. 13
101
Identification of sakat tree found at sample plot no. 23 with coordinates N
15’21” and E 120’09” located at Mount Nagparel Brgy. Sta. Barbara, Iba,
Zambales
102
Pictures showing the members of the Biodiversity Assessment Team
traversing Baquilan river with a carabao cart
103
Portion of Poonbato river within the Bucao Watershed heavily silted with lahar.
104
Stop-over along the middle portion of Bucao Watershed located at Burgos,
Botolan, Zambales. Alongside shows the massive river bank erosion.
105
Ongoing construction of Villar Brgy Hall located along the upper portion of the
watershed
106
Portion of Mt. Culianan at Maguisguis, Botolan, Zambales showing the extent
of erosion within Bucao Watershed
107
Pictures showing the assessment team caravan while passing along piles of
lahar deposit continuously eroded by the flow of Balinbaquero river at Villar,
Botolan, Zambales.
108
Showing the extent of massive soil erosion and siltation of Bucao river.
109
Pictures showing the carabao carts hired by the assessment team. On the
background is the tree plantation of BAFI continuously eroded by the river at
Poonbato, Botolan, Zambales
110
Another stopover of the assessment team together with the participating
community after 6 hours of continuous travelling
111
FAUNA
MAMMALS
112
INSECTS
113
Beehive found at So.Maimit, Brgy. Maamot, San Jose, Tarlac
114
References:
Department of Environment and Natural Resources (DENR).2001, DAO No. 34,
Series of 1990. Revised Water Usage and Classification: Water Quality Criteria
Amending Section Nos. 68 and 69, Chapter III of the 1978 NPCC Rules and
Regulations.
Department of Environment and Natural Resources (DENR).2008. DAO No. 05
Series of 2008, Implementing Guidelines in the Preparation of Integrated Watershed
Management Plan.
Series of 2007
Series of 2004
Integrated Coastal Resources Management Project (ICRMP) Development Plan of
Botolan, Zambales
Integrated Coastal Resources Management Project (ICRMP) Development Plan of
Cabangan, Zambales
Municipality of Botolan, Zambales. The Municipal Planning and Development
Officers (MPDO) and Municipal Health Officers of Botolan.
Municipality of Iba, Zambales. The Municipal Planning and Development Officers
(MPDO) and Municipal Health Officers of Iba.
Municipality of Cabangan, Zambales. The Municipal Planning and Development
Officers (MPDO) and Municipal Health Officers of Cabangan.
Municipality of San Felipe, Zambales. The Municipal Planning and Development
Officers (MPDO) and Municipal Health Officers of San Felipe.
Municipality of San Marcelino, Zambales. The Municipal Planning and Development
Officers (MPDO) and Municipal Health Officers of San Marcelino.
Municipality of San Jose, Tarlac City. The Municipal Planning and Development
Officers (MPDO) and Municipal Health Officers of San Jose.
Municipality of Capas, Tarlac. The Municipal Planning and Development Officers
(MPDO) and Municipal Health Officers of Capas.
National Statistics Office (NSO) Olongapo City Branch Office. Census and
Population 2007.
Philippine Atmospheric, Geophysical and Astronomical Services Administration
(PAGASA). SBMA Weather Station.
115
Procedural Manual on Water Quality (Volume 1 Ambient Water Quality Monitoring)
Monitoring. October 26, 2007. Environmental Management Bureau, Department of
Environment and Natural Resources Region 3.
116

bUCAO WATERSHED CHARACTERIZATION - Phil

Transcription

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