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 AUGUST 2019

OVERVIEW

Harvesting has started for upland 1st palay in most parts of the country and lowland 1st palay in Infanta and Daet. Good to normal yield is expected in Cagayan Valley, most of Central Luzon, Tayabas, Romblon, Masbate, and Davao, due to the sufficient moisture received by the crops from planting to maturity. In contrast, below normal yield is anticipated in Ilocos Region, Cordillera Autonomous Region, Infanta, and Camarines Norte because the crops suffered from water logging and moisture stress during the critical stage of growth. Standing crops are in good condition in most of Central Luzon, Tayabas, Ambulong, most parts of MIMAROPA, Panay Island, Catarman, Catbalogan, Zamboanga del Norte, Bukidnon, Misamis Oriental and Davao region. However, crops are suffering from moisture stress in the areas of Laoag, Sinait, Cordillera Autonomous Region, Baler, Infanta, Pto. Princesa, Camarines Norte, Masbate, Central Visayas, Tacloban, Zamboanga del Sur, Gen. Santos, Surigao del Sur and ARMM.

The weather systems that affected the country during the month were the Southwest (SW) monsoon, low pressure areas (LPAs), localized thunderstorms and the passage of three (3) tropical cyclones (TCs) namely: Typhoon (TY) “Hanna” (Aug. 3-8), Severe Tropical Storm (STS) “Ineng” (Aug. 20-24) and Tropical Storm (TS) “Jenny” (Aug. 26-28). TS Jenny made landfall in Aurora but only brought minimal rains to the country. Meanwhile, TY Hanna and STS Ineng did not make landfall but both TCs enhanced the southwest monsoon and brought moderate to heavy rains over Luzon and to western parts of Visayas. Moreover, classes and work suspension were declared due to flood occurences caused by TY Hanna in Metro Manila, Central Luzon, CALABARZON, MIMAROPA, Central and Western Visayas and Ilocos Region. Ilocos Norte was brought under a state of calamity when it incurred millions of Agricultural damages due to STS Ineng as reported by the National Disaster Risk Reduction and Management Council (NDRRMC). The rainfall from the TCs increased the water level on several dams in Luzon.

Rainfall assessment during the month indicated that most parts of Luzon received near to above normal rainfall, including some portions of Visayas and Mindanao. The rest of the country experienced below normal rainfall conditions.

REGIONS

Harvesting of upland 1st palay now commences in Ilocos region; below normal yield may be anticipated because of water logging brought by tropical cyclones that passed through the region. Likewise, the standing, newly-planted lowland palay, as well as the vegetating, delay-planted upland palay might also be affected by such destructive calamities.
Harvesting of upland 1st palay had just started; good yield may be anticipated in Batanes and Cagayan Valley because palay recovered from moisture stress due to the adequate moisture received. The standing newly planted lowland 1st palay is faring across the region, it is due to sufficient rains received during the month.
Harvesting of upland 1st palay had just started throughout the region; below normal yield is expected because of the passage of tropical cyclones which brought stormy weather and heavy rains. Crops are submerged in water and muds. The standing, newly-planted lowland palay as well as the delay-planted upland palay might also be affected by such calamities during the month.
Harvesting of upland 1st palay had just begun in most parts of the region; good to normal yield are probable because crops experienced favorable condition during the entire growing season. Rainfall received during the month is favorable for the vegetating, delay-planted upland palay and newly-planted lowland palay in most parts of the region, except in Baler. In that particular area, rains received during the month is very low.
Harvesting of upland 1st palay in Tayabas and lowland 1st palay in Infanta has commenced; good to normal yield is expected in Tayabas due to the sufficient moisture experienced by the crops from planting to maturity, while below normal yield is anticipated in Infanta because crops experienced moisture stress during the critical stage of growth and development. Sufficient rainfall received during the month is favorable for the standing crops in Tayabas and Ambulong.
Harvesting of upland 1st palay had just begun in Romblon; yield is expected to be good to normal because crops recovered from moisture stress during the critical stage of growth. Sufficient moisture available during the month favors the vegetating upland palay and the newly planted lowland palay in most parts of the region. However, crops are suffering from moisture deficiency in Pto Princesa.
Harvesting of upland 1st palay in Masbate and lowland 1st palay in Camarines Norte had just started; yield in Masbate is expected to be good to above normal because crops experienced good condition though-out its growing period while in Camarines Norte yield is below normal due to moisture deficiency during its critical stage of growth and development. Standing crops in Masbate experienced moisture deficiency because of scarcity of rains received during the month.
The standing newly planted lowland 1st palay suffered from moisture stress throughout the region due to insufficient moisture during the month.
The ample amount of rainfall received during the month are favorable for the newly planted delay-planted lowland 1st palay across the region.
The standing upland and lowland 1st palay in Catbalogan and Catarman are in good condition due to the sufficient moisture available during the month, unlike in Tacloban, crops experienced moisture stress due to very low rainfall received.
The vegetating, delay-planted upland 1st palay in Zamboanga del Norte is faring well because of the sufficient moisture during the month. In contrast, the newly-planted and delay-planted lowland palay in Zamboanga del Sur experienced moisture stress due to the minimal rainfall received during the month.
Harvesting of upland 1st palay now started in Bukidnon; good to normal yield is anticipated this season due to sufficient moisture supply and favorable weather condition experienced by the crops during the critical stage of growth and development. Sufficient moisture obtainable during the month favors the standing, newly planted and late-planted lowland 1st palay as well as the vegetating, late-planted upland palay in Bukidnon. Crops are all in good condition.
Good to normal yield is expected this season for the harvestable, upland 1st palay planted in May since crops experienced favorable condition throughout the growing period. Standing, upland 1st planted crops in June are faring well due to good weather and sufficient moisture available during the month.
The standing, newly-planted lowland 1st palay experienced moisture stress due to the insufficient amount of moisture available during the month.
The vegetating, lowland 1st palay in Surigao del Sur experienced moisture stress because of inadequate moisture available during the month.
The newly-planted, lowland 1st palay across the region experienced moisture stress due to scarcity of moisture during the month.

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