Climate Impact Assessment
Climate Impact Assessment and Applications Section Climatology and Agrometeorology Branch
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)
Department of Science and Technology
April 2008
Number 04 / Volume 24
The Climate Impact Assessment and Applications
Section (CIAAS) of PAGASA’s Climatological Branch regularly issue this monthly/bulletin which will provide users such as food security managers, economic policy makers, agricultural statisticians and agricultural extension officials with qualitative information on the current and potential effects of climate and weather variability on rainfed crops, particularly rice and corn. This bulletin, entitled “Climate Impact Assessment for Agriculture in the Philippines”, represents a method for converting meteorological data into economic information that can be used as supplement to information from other available sources.
For example, an agricultural statistician or economist involved in crop production and yield forecast problems can combine the assessment with analysis from area survey results, reports on the occurrence of pests and diseases, farmers reports and other data sources.
The impact assessments are based on agroclimatic indices derived from historical rainfall data recorded for the period 1951 to the present. The indices, expressed in raw values percent of normals and percentile ranks, together with real time meteorological data (monthly rainfall, in percent of normal), percent of normal cumulative rainfall, as well as the occurrence of significant event such as typhoons, floods and droughts are the tools used in the assessment of crop performance. Crop reports from PAGASA field stations are also helpful.
The narrative impact assessment included in the bulletin depicts the regional performance of upland, 1st lowland and 2nd lowland palay; and dry and wet season corn crops, depending on the period or the season. Tabulated values of normal rainfall and generalized monsoon and yield moisture indices are provided for ready reference. Spatial analysis of rainfall, percent of normal rainfall and the generalized monsoon indices in percentile ranks are also presented on maps to help users visualize any unusual weather occurring during the period. The generalized monsoon indices in particular, are drought indicators; hence, the tables (see Appendices) together with the threshold values can be used in assessing drought impact, if there are any. It also help assess any probable crop failure.
It is hoped therefore that this bulletin would help provide the decision-makers, planners and economist with timely and reliable early warning/information on climatic impact including the potential for subsistence food shortfalls, thereby enabling them to plan alternate cropping, if possible, food assistance strategies / mitigation measures to reduce the adverse impact of climate and eventually improve disaster preparedness.
Impact assessment for other principal crops such as
sugarcane and coconut, for energy and for water resources management, are from time to time will be included in the forthcoming issues of this bulletin.
The Climate Impact Assessment and Applications Section (CIAAS) of the Climatological Branch will appreciate suggestions/comments from end-users and interested parties for the improvement of this bulletin.
Definition of Terms The Generalized Monsoon Index (GMI) helps determine
the performance of the rains during the season and serves as a good indicator of potential irrigation supplies. It is a tool used to assess rainfed crops.
The GMI for the southwest monsoon (GMIsw) in an area during June to September is defined as follows:
GMIsw = W6P6+W7P7+W8P8+W9P9
The GMI for the northeast monsoon (GMIne) in an area during October to January is defined as:
GMIne = W10P10+W11P11+W12P12+W1P1
where: W =weight coefficient of monthly rainfall
for the season; P = rainfall amount in the ith month (i=1 for
January, 1=2 for February, etc.)
The Yield Moisture Index (YMI) is a simple index that helps the users assess agroclimatic crop conditions during the crop season. The YMI for a particular crop is defined as follows:
n YMI =Σ Pi Ki i where:
I = the crop stage (1=planting/ transplanting, 2=vegetative,
3= flowering, 4 = maturity, etc.) n = total no. of crop stages; P = the rainfall during the ith crop stage; and K = is the appropriate crop coefficient for the
ith crop stage. Tentatively, the threshold values of categories of
indices for interpretation being adopted for both YMI and GMI are as follows:
Percentile
Rank Interpretation
> 80 Potential for flood damage 41-80 Near normal to above- normal crop
condition 21-40 Moderate drought impact with
reduced yield 11-20 Drought impact with major yield losses
PREFACE
< 10 Severe drought impact with crop failure and potential food shortages
AAGGRROOCCLLIIMMAATTIICC // CCRROOPP CCOONNDDIITTIIOONN AASSSSEESSSSMMEENNTT FFOORR AAPPRRIILL 22000088
Overview
In most part of the country, harvesting of lowland second palay is going on. The
now flowering as well as the newly planted corn crops continued to experience
sufficient moisture supply.
Above normal rainfall conditions was observed over the Visayas, most parts of
Mindanao, most areas of Southern Luzon including Bicol Region, and some areas in
the western and central Luzon. The rest of the country experienced near to below
normal rainfall condition. Rainfall during the period was caused by the tail end of Cold
Front, the Easterly Wave, the ridge of High Pressure area, the Intertropical
Convergence Zone (ITCZ) and one (1) Tropical Cyclone. Tropical Storm “Ambo” (April
14-15), embedded along the ITCZ was the first tropical cyclone enter and cross the
country through southern portion of Visayas towards Palawan area.
Region I In most part of the region, harvesting of rainfed rice and corn crops with below normal harvest obtained.
CAR Harvesting of lowland palay is in full swing anticipating near normal yield. Region II In Cagayan Valley, harvesting of lowland second palay is going on. Near to above normal harvest is expected.
Region III Harvesting of lowland second palay and dry season corn crops is already completed. In eastern part of the region, crop condition for early planted wet season corn now on its flowering stage is near to above normal as suggested by yield moisture indices.
Region IV Harvesting of lowland second palay is going on. Normal harvest is expected. The February planted wet season corn now on its flowering stage is benefited by sufficient moisture supply experienced in the area. Crop condition is near to above normal. Region V In most part of the region, harvesting of lowland second palay is going on. Wet season corn crops now on its flowering stage experienced above normal rainfall in April. Land preparation and planting of dry season corn is going on. Region VI In western Visayas, harvesting of lowland palay is in progress, good yield is expected.
Region VII Harvesting of lowland second palay is going on. Near to above normal harvest anticipated. Region VIII
Harvesting of rainfed lowland
palay is in full swing. The now flowering wet season corn experienced above normal rainfall. Yield moisture indices on the 97th and 98th percentile rank suggested possibility of flood damages.
Region IX Harvesting of lowland palay is going on expecting near to above normal harvest.
Region X In northern Mindanao, harvesting of lowland palay is in progress with good yield expected. Region XI Harvesting of lowland palay is in progress anticipating near to above normal harvest. Region XII In Central Mindanao, harvesting of rainfed rice is still going on. Above normal yield is expected. CARAGA Harvesting of second palay is in full swing. The now flowering as well as the newly planted corn crops experienced above rainfall. ARMM Harvesting of rainfed rice and corn crops is going on. Near to above normal harvest expected this season.
For Particulars, please contact: Carmelita A. Vindollo and/or Irene P. Pabona Climate Impact Assessment and Applications Section (CIAAS) Climatology and Agrometeorology Branch (CAB) PAGASA-DOST Telefax No.: 4345882
Table 1.0 Cumulative Yield Moisture Indices for Early Planted Wet Season Corn (February 2008 – April 2008) in Millimeters and Percentile Rank.
FEBRUARY MARCH APRIL STATIONS YMI %RANK YMI %RANK YMI %RANK
Region III Baler Casiguran
212 245
95 92
391 334
71 74
576 459
76 66
Region IV Alabat Ambulong Infanta Tayabas
442 19
516 133
98 87 98 87
602 38 854 197
97 82 97 71
724 61
1114 315
97 61 95 79
Region V Daet Legaspi Masbate Virac
654 703 211 377
98 98 95 97
980
1005 252 626
98 97 84 98
1103 1393 349 915
98 98 89 98
Region VIII Catarman Catbalogan Tacloban
809 722 581
98 98 98
1247 957 880
95 98 98
1611 1105 1103
97 98 98
CARAGA
Butuan Hinatuan Surigao
175 517 450
68 84 84
421
1224 1146
89 95 98
562 1579 1313
89 92 95
ARMM Cotabato
85
82
318
97
599
95
Table 2.0 Yield Moisture Indices for Dry Season Corn ( April – June 2008 ) in Millimeters and Percentile Rank.
APRIL MAY JUNE STATIONS YMI % RANK YMI % RANK YMI % RANK
Region IV Infanta
225
87
Region V Daet Legaspi Virac
107 336 251
71 97 97
Region VIII Catarman
315
97
CARAGA Surigao Hinatuan
145 307
68 84
Table 3.0 Decadal and Cumulative Decadal Rainfall (Actual and Percent of Normal) for April 2008
REGION DECADE ACTUAL % CUMULATIVE % I Ilocos Region
10 11 12
1 13 51
10 81
255
78 91
142
104 100 128
CAR
10 11 12
1 18 49
9 95
223
135 153 202
225 194 200
II Cagayan Valley
10 11 12
2 17 53
10 74
294
278 295 348
133 127 139
III Central Luzon
10 11 12
16 19 48
64 70
200
316 335 383
127 122 128
NCR
10 11 12
6 6
24
86 100 171
106 112 136
238 222 211
IV Southern Tagalog
10 11 12
26 55 57
124 229 204
450 505 562
161 167 170
V Bicol Region
10 11 12
60 95
102
143 279 291
1307 1402 1504
255 257 259
VI Western Visayas
10 11 12
15 48 88
71 267 314
313 361 449
186 194 210
VII Central Visayas
10 11 12
9 54 86
47 360 410
515 569 655
192 200 215
VIII Eastern Visayas
10 11 12
76 91
129
181 186 331
1867 1958 2087
247 243 247
IX Western Mindanao
10 11 12
43 53 51
187 161 222
529 582 633
230 221 221
X Northern Mindanao 10 11 12
21 50
102
75 172 351
487 537 639
142 144 159
XI Davao Region
10 11 12
33 36 60
92 69 92
715 751 811
122 118 116
XII SOCSARGEN
10 11 12
21 26 77
88 87
296
335 361 438
135 130 144
XIII CARAGA
10 11 12
56 63
117
102 93
165
1272 1335 1452
113 110 113
ARMM
10 11 12
35 71 94
152 187 336
418 489 583
180 181 196
Fig.1.0 Actual Rainfall (mm) Distribution in the Philippines for the Month of April 2008.
Fig. 1.2 Percent of Normal Rainfall in the Philippines for the month of April 2008
Fig. 2.0 Cumulative Rainfall during the passage of Tropical Storm “AMBO” ( April 14-15, 2008)
Fig. 3.0 Comparison of Normal Rainfall and Potential Evapotranspiration with the Actual
Monthly Data at Laoag, Baguio, Dagupan, Basco, Aparri and Tuguegarao.
Fig. 3.a. Comparison of Normal Rainfall and Potential Evapotranspiration with the Actual Monthly Data at Iba, Muñoz, Science Garden, Ambulong, Calapan and Port Area..
Fig. 3.b. Comparison of Normal Rainfall and Potential Evapotranspiration with the Actual Monthly Data at Puerto Princesa, Casiguran, Infanta, Alabat, Daet and Legaspi
Fig. 3 c. Comparison of Normal Rainfall and Potential Evapotranspiration with the Actual Monthly Data at Cuyo, Iloilo, Dumaguete, Masbate, Mactan and Tacloban.
Fig. 3.d. Comparison of Normal Rainfall and Potential Evapotranspiration with the Actual Monthly Data at Catarman, Cagayan de Oro, Davao, Dipolog, Zamboanga and General Santos.
