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 2018

OVERVIEW

Land preparation, planting and transplanting activities related to planting late-planted lowland 2nd palay as well as dry-season corn have just begun in Aparri, Basco, Baler, Casiguran, CALABARZON, Calapan, Romblon, Bicol Region, Panay Island, most parts of Region VII, Catbalogan, Tacloban, Zamboanga del Norte, Davao, and CARAGA Region. Those areas received sufficient amount of rainfall needed for planting rice and corn crops. Contrastingly, any planting activity may be hampered in Ilocos Region, CAR, Tuguegarao, most of MIMAROPA, Dumaguete, Zamboanga del Sur, Region X, XII, and ARMM because of inadequate moisture available during the month. Standing rice and corn in Casiguran, Tayabas, Calapan, Romblon, Panay Island, Catarman, Catbalogan, and CARAGA are in good crop condition. While in Bicol region newly planted rice and corn could be damaged by water logging because of the excessive amount of from the passage of TD “Usman”.

Rainfall assessment during the month of December showed that a large portion of the country experienced near normal to above normal rainfall conditions. However, patches of below normal rainfall in Ilocos Norte and Western Mindanao were experienced which led to Meteorological dry spell.

The weather systems that affected the country during the month were the Northeast Monsoon (NE), Low Pressure Areas (LPAs), easterlies, tail-end-of a cold front and the passage of tropical depression (TD) “Usman”. TD “Usman” brought significant and extreme rainfall that caused massive floods in areas of CALABARZON, MIMAROPA, Region V, Region VI, and Region VIII. It also caused massive landslides in Bicol area, MIMAROPA, Region V, and Region VIII. These resulted to more than two hundred casualties, damage to infrastructures and agriculture, and prompted the declaration of state of calamity over the provinces of Albay, Sorsogon, Camarines Norte Camarines Sur and eight (8) municipalities of Oriental Mindoro as reported by the National Disaster Risk and Management Council (NDRRMC), dated 10 January 2019 (as per the Situation Report No. 22 of the NDRRMC).

REGIONS

Planting of lowland 2nd palay and dry season corn will not be possible in any part of the region because of very low moisture available during the month.
Land preparation, as well as the planting and transplanting of late-planted, lowland 2nd palay and dry season corn had just begun in most parts of the region. In Tuguegarao, however, planting activities might be hampered due to the unavailability of moisture during the month
Planting of late planted, lowland 2nd palay as well as dry season corn will not be possible across the region because of the unavailability of moisture during the month.
Suffficient moisture favors land preparation, planting and transplanting activities for late-planted lowland 2nd palay and dry season corn, which had just begun in Baler and Casiguran. On the other hand, in the western part of the region, farming activities may be hampered by the very low rainfall received during the month. Newly-planted, lowland 2nd palay in Casiguran are in good condition.
Land preparation, planting and transplanting activities for late-planted lowland, 2nd palay as well dry season corn had just begun across the region due to the sufficient moisture available during the month. Standing, early-planted dry-season corn and lowland 2nd palay in Quezon province are faring well.
Land preparation, planting and transplanting activities for late-planted, lowland 2nd palay as well as dry season corn in Calapan and Romblon had just begun; adequate rainfall available during the month favors the same. Meanwhile, in other parts of the region, all farming activities are hindered due to the insufficient moisture in those areas. Standing crops in most parts of the region are in good condition.
Land preparation, planting and transplanting activities pertaining to late-planted, lowland 2nd palay as well as dry-season corn had just begun across the region. Sufficient moisture favors such activities. Standing rice and corn crops may have been damaged by water logging during the passage of TD Usman. Most of Bicol region was devastated by such tropical cyclone.
In most parts of the region, land preparation, planting and transplanting activities for late-planted, lowland 2nd palay and dry-season corn had just begun. Meanwhile, farming activities related to planting late-planted lowland 2nd palay and dry season corn in Negros Oriental will not be possible due to the minimal rainfall received during the month.
Ample amount of rainfall received in Roxas favors land preparation, planting and transplanting activities for dry season as well as late-planted, lowland palay. Standing, early-planted dry season corn crops are in good condition.
Land preparation, planting and transplanting activities pertaining to planting late-planted lowland 2nd palay and dry-season corn across the region is favored by the sufficient moisture available. Standing, lowland 2nd palay crops also benefit from sufficient moisture
Sufficient moisture favors land preparation, planting and transplanting activities for dry season corn as well as late-planted, lowland 2nd palay in Zamboanga del Norte. Meanwhile in Zamboanga del Sur, farming activities are hindered by the scarce moisture available during the month.
Farming activities are hindered in the region because of very low rainfall received during the month.
Land preparation, planting and transplanting activities for late-planted, lowland 2nd palay as well as dry-season corn had just begun across the region. Sufficient moisture is available during the month.
Farming activities related to the planting of rice and corn is hampered because of the scarce moisture across the region.
Land preparation, planting and transplanting activities related to planting late planted lowland 2nd palay, as well as dry season corn, had just started. Adequate moisture available during the month favors the same. The standing November-planted lowland 2nd palay are in good crops condition.
Farming activities related to the planting of rice and corn is hampered because of the scarce moisture across the region.

Ten Day Rainfall Distribution

Monthly Rainfall Distribution

Generalized Moonsoon Index

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