Impact Assessment for Agriculture
Preface

The Impact Assessment and Applications Section (IAAS) of Climatology and Agrometeorology Division (CAD) 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 helps 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 IAAS of CAD 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, 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 =  [Pi Ki] i

where:

i = crop stage (1 = planting/transplanting,
2 = vegetative, 3 = flowering, 4 = maturity, etc.)
n = total no. of crop stages;
P = rainfall during the ith crop stage; and
K = 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:


PERCINTELE 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
< 10 Severe drought impact with crop failure and potential food shortages

Agroclimatic / AGROCLIMATIC / CROP CONDITION ASSESSMENT FOR DECEMBER 2019

OVERVIEW

Land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry-season corn has now started in Aparri, Basco, Tuguegarao, Baler, Casiguran, CALABARZON, most parts of MIMAROPA, Bicol Region, Panay Island, Eastern Visayas, Mactan, Dipolog, Surigao del sur and Surigao del Norte. Those areas received sufficient amount of rainfall needed for planting rice and corn crops. In contrast, any planting activities might have been hampered in CAR, Ilocos region, Zambales, Cabanatuan, Cuyo, Puerto Princesa, Bohol, Negros Oriental, Zamboanga del Sur, Misamis Oriental, Bukidnon, Davao region, SOCSARGEN, Butuan and ARMM because of inadequate moisture available during the month. Standing newly planted lowland 2nd palay is faring well in Casiguran, most of CALABARZON, Calapan, Coron, BIcol Region, Catarman, Surigao del Sur and Surigao del Norte. Early-planted dry season corn in Tuguegarao, Tayabas, Calapan, Romblon, Masbate, and Panay Island are in good crops condition. Contrastingly, standing crops in Ilocos Sur, Ilocos Norte, and Cabanatuan experienced moisture stress.

The weather systems that affected the country during the month were the Northeast (NE) Monsoon, Low pressure Areas (LPAs), Tail end of Cold Front, Easterlies, Inter-tropical convergence zone (ITCZ), and the passage of two (2) tropical cyclones (TCs) namely: Typhoon (TY) “Tisoy” (30 November - 05 December), and Typhoon (TY) “Ursula” (December 23-28). From a tropical depression, both TY “Tisoy” (with international name “Kammuri”) and TY “Ursula” (with international name “Phanfone”) rapidly became a typhoon as they traversed eastern and northern Visayas. These brought significant rainfall and strong winds that caused damages to properties and casualties in areas of CALABARZON, MIMAROPA, Regions V, VI, VIII and CARAGA. Domestic and international flights were also cancelled due to bad weather, as reported by the National Disaster Risk Reduction and Management council (NDRRMC), dated 28 December 2019 (Sit Rep No. 12).

General assessment of rainfall for the month showed that near to above normal rainfall conditions were received in most parts of Luzon, most parts of the Visayas and some parts of Davao Region. Meanwhile, below to way below normal rainfall conditions were experienced in the remaining parts of Mindanao.

REGIONS

Land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry season corn in Ilocos region may be hampered because of inadequate rainfall received during the month. Hence, newly planted lowland 2nd palay in Ilocos sur and Ilocos Norte now suffered moisture stress.
Land preparation, planting and transplanting activities for late- planted lowland 2nd palay as well as dry season now started in Cagayan Valley. Sufficient moisture received during the month also favors early planted dry-season corn, crops are in good condition in Tuguegarao.
Any planting activities related to planting rice and corn may not be undertaken across the region because of insufficient moisture available during the month
Land preparation, planting and transplanting activities for dry-season corn and late-planted lowland 2st palay had commenced in Baler and Casiguran because of sufficient moisture available during the month, while in Zambales and Cabanatuan due to inadequate rainfall received, all farming activities are hampered. Likewise, early planted dry season corn in Cabanatuan is affected by moisture stress, while crops in Casiguran is faring well.
In CALABARZON, adequate moisture favors the land preparation, planting, and transplanting activities for late-planted lowland 2nd palay as well as dry season corn. Standing early planted dry-season corn and the newly –planted lowland 2nd palay in Quezon experienced good crops condition.
Land preparation, planting and transplanting activities for lowland 2nd palay as well as dry season corn had just begun in most parts of the region. Such activities were favored by sufficient moisture supply available during the month. In contrast, inadequate moisture in Cuyo and Puerto Princesa, hampered any farming activities to be done. Meanwhile, standing rice and corn crops in Romblon, Coron and Calapan are faring well.
Land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry season corn have just commenced across the region. These were made possible despite of below normal rainfall received during the month in Albay and Camarines Norte but still sufficient for such farming activities. Standing rice and corn crops experienced good crops condition.
Sufficient moisture available during the month favors land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry season corn in Mactan, On the contrary, any farming activities related to planting rice and corn in Bohol and Negros Oriental might be hampered because of very low rainfall received during the month.
Good weather and well-distributed rainfall received during the month is beneficial for land preparation and planting activities for early-planted dry season corn across the region.
Sufficient rainfall received during the month favors land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry-season corn in most parts of the region. Standing newly-planted lowland 2nd palay in Catarman experienced good crops condition.
In northern part of the region, ample amount of rainfall received during the month has favored land preparation, planting and transplanting activities for late-planted lowland 2nd palay as well as dry season corn. While in the southern part, any farming activities related to planting rice and corn across the region might be hampered due to very minimal rainfall received during the month.
Inadequate moisture available in Misamis Oriental and below normal rainfall received in Bukidnon indicate that land preparation, planting, and transplanting activities related to rice and corn may not be possible to be undertaken.
Good weather prevailed during the month but moisture available are not sufficient for planting rice and corn of any kind across the region.
Inadequate rainfall received all over the region might have hampered any farming activities to be done during the month.
Land preparation, planting, and transplanting activities for late-planted lowland 2nd palay as well as dry season corn have started in most parts of the region. Sufficient moisture favored such activities except in Butuan, inadequate rainfall received during the month, hampered such farming activities to be done. Standing lowland 2nd palay in Surigao del Norte and Surigao del sur are faring well.
Very low rainfall received during the month hampered any farming activities to be done relative to planting rice and corn.

Ten Day Rainfall Distribution

Monthly Rainfall Distribution

Generalized Moonsoon Index

Tropical Cyclone

Actual Rainfall and Potential Evapotranspiration

Stations

For Particulars, please contact:

THELMA A. CINCO


Impact Assessment and Applications Section (IAAS)

Climatology and Agrometeorology Division (CAD)

PAGASA-DOST

Telefax No.: 434-58-82