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 / CLIMATE IMPACT ASSESSMENT for Philippine Agriculture (Rice and Corn)

OVERVIEW

Harvesting of upland and lowland 1st palay have just begun in some areas of the country. Good to normal yield is expected in Baler, Tayabas, Calapan, Albay, Panay Island, Catbalogan, Tacloban, Bukidnon, Surigao del sur and ARMM, while below normal yield is anticipated in CAR, and Davao Region. Standing crops in Batanes, Tayabas, Ambulong, Calapan, Camarines Norte, Panay Island, Bukidnon, and ARMM are in good condition. Those in Tuguegarao, Baler, Tayabas, Calapan, Catanduanes, Catbalogan, Tacloban and Surigao del Norte have experienced moisture stress. In Pangasinan, CAR, Nueva Ecija and Zambales, the standing crops suffered from water logging.

Rainfall assessment for the month of August showed that most parts of Cordillera Administrative Region (CAR), Regions I and III, including the provinces of Batanes, Nueva Viscaya and Rizal experienced above normal rainfall conditions. However, most parts of Southern Luzon, Visayas and Mindanao received below to way below normal rainfall while the rest of the country experienced near normal rainfall conditions.

The weather systems that affected the country during the month were the enhanced Southwest (SW) monsoon, Low Pressure Areas (LPAs), localized thunderstorms, ridge of High Pressure Areas (HPAs) and the passage of two (2) tropical cyclones (TCs), namely: Tropical Storm (TS) “Karding” (August 7 -10) and Tropical Depression (TD) “Luis” (August 23-24). Both TCs enhanced the Southwest monsoon and brought moderate to heavy rains that resulted to flooding in most parts of Luzon. Over 150,000 families were affected. Class and work suspensions were also declared due to floodings in Region I, II, III, CAR, CALABARZON and Metro Manila, based on the report of the National Disaster Risk and Management Council (NDRRMC).

REGIONS

Sufficient rainfall received during the month is favorable for land preparation, planting, and transplanting activities related to late-planted upland 1st palay across the region.
Land preparation, planting, and transplanting activities pertaining to late-planted upland palay has just begun in Babuyan island except in Calayan, adequate moisture available during the month favors the same. In most parts of Cagayan Valley, any farming activities cannot possibly be done due to scarcity of rainfall over those areas.
Land preparation, planting, and transplanting activities for late-planted upland 1st palay has now started because of sufficient moisture available during the month. Similarly, the standing newly planted upland 1st palay, as well as vegetating wet season corn crops, experienced good crops condition.
In most part of the region, land preparation, planting and transplanting activities for late-planted upland 1st palay have commenced. These activities are favored by sufficient moisture available during the month. Similarly, the standing wet season corn, as well as the newly planted upland 1st palay, particularly in Baler are fairing well.
Land preparation, planting, and transplanting activities related to late-planted upland 1st palay have just begun in Ambulong and Tayabas. In Infanta and nearby provinces, however, any farming activities related to late- planted lowland 1st palay may not have been possibly done due to insufficient moisture available in the area. Meanwhile, the standing crops, wet season corn and the newly-planted upland 1st palay, in Tayabas experienced good crops condition.
Land preparation, planting, and transplanting activities for late-planted upland 1st palay, have just begun in most parts of the region except in Puerto Princesa. These activities were favored by adequate rainfall received during the month. Consequently, the standing newly-planted-upland 1st palay as well as vegetating wet season corn experienced good crops condition in Calapan.
Harvesting of dry season corn has just begun in Camarines Norte; below normal yield is expected this season because of moisture stress experienced by the crops during their vegetative stage. Likewise, standing newly planted lowland 1st palay in Albay experienced moisture stress. In contrast, sufficient moisture available during the month favors land preparation, planting, and transplanting activities for late-planted lowland 1st palay in Catanduanes and Camarines norte. In Masbate, any farming activities pertaining to late-planted upland palay might have been hampered.
Because of insufficient moisture available during the month, any farming activities pertaining to late-planted 1st upland palay could not be possibly done in any part of the region.
In Panay Island, land preparation, planting, and transplanting activities for late-planted upland 1st palay have just begun. Adequate moisture received during the month favored such activities. In the same way, the standing wet season corn, now vegetating, as well as the newly-planted upland 1st palay are faring well.
Harvesting of dry season corn has just started in Catarman, below normal yield is anticipated because the crops experienced moisture stress during their vegetative stage. Nevertheless, land preparation, planting, and transplanting activities for late-planted lowland 1st palay were favored by sufficient rainfall in Catbalogan and Tacloban, but not in Catarman. Standing wet season corn and upland palay in Catbalogan and Tacloban are in good crops condition.
Any farming activities related to planting of delayed-planted upland palay will not be possible across the region; it is due to very low rainfall received during the month. The standing wet season corn, currently vegetating, as well as newly planted upland 1st palay in Zamboanga del Norte were also affected and as of now experiencing moisture deficiency.
Land preparation, planting, and transplanting activities for late-planted 1st upland palay was favored by good weather and sufficient moisture supply available all over the region. Likewise, standing wet season corn, which are now vegetating, and the newly planted upland 1st palay are in good crops condition in Bukidnon.
Land preparation for late-planted upland palay may be hampered across the region; it is due to insufficient amount of moisture available during the month. Consequently, standing newly planted 1st upland palay, as well as vegetating wet season corn, were also affected and now experiencing moisture stress.
Insufficient rainfall received during the month made it impossible for any farming activities to be done across the region.
Harvesting of dry season corn has now started across the region; good to normal yield is expected in Surigao del Sur, but in Surigao del Norte, below normal yield is anticipated. Land preparation, planting, and transplanting activities for late-planted lowland 1st palay have now started in Surigao del Norte because of sufficient moisture received during the month. In contrast, any farming activities might have been hampered in Surigao del Sur because of inadequate rainfall received over the area. Consequently, newly planted lowland 1st palay in Surigao del Sur is experiencing moisture stress.
The standing upland 1st palay crops all over the region are in good condition because of favorable weather and sufficient moisture available during the month.

Tropical Cyclone

No Active 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