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 SEPTEMBER 2019

OVERVIEW

Harvesting of late-planted upland 1st palay in most parts of the country and late-planted lowland 1st palay in Legaspi, Virac, Catarman, Tacloban and Hinatuan had just begun; good to normal yield is expected in Dagupan, Nueva Ecija, Coron, Cuyo, San Jose, Albay, Catanduanes, Malaybalay, and Davao, due to sufficient moisture experienced by the crops from planting to maturity. In contrast, below normal yield is anticipated in Ilocos Sur, Ilocos Norte, Cordillera Autonomous Region (CAR), Zambales, Aurora, Pto. Princesa, Tacloban, Dipolog, and Bukidnon because crops suffered from water logging and moisture stress during the critical stage of growth. Standing crops are suffering from moisture stress in most of CAR, Ilocos Provinces, Central Luzon, Tayabas, Ambulong, most parts of MIMAROPA, Masbate, and Bukidnon, are in good condition, but in Panay Island, Central Visayas, Catbalogan, Dipolog, Misamis Oriental and SOCCSKSARGEN.

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 five (5) tropical cyclones (TCs) namely: Tropical Depression (TD) “Kabayan” (September 1), Typhoon (TY) ”Liwayway” (September 1-5), tropical Depression (TD) “Marilyn” (September 12-14), Severe Tropical Storm (STS) “Nimfa” (September 17-20) and Typhoon (TY) “Onyok” (September28-30). All TCs did not make landfall but enhanced the southwest monsoon, which caused floodings and class suspensions, as indicated in the Situational Report (SitRep) by the National Disaster and Reduction Risk Management Council (NDRRMC).

Rainfall assessment during the month indicates that most parts of Luzon experienced near to above normal rainfall conditions, including Guimaras, Iloilo, and Basilan in the Visayas and Mindanao. The rest of the country experienced below normal rainfall conditions.

REGIONS

Harvesting of late-planted, upland 1st palay has started in Ilocos region; below normal yield may be anticipated because of water logging brought by TCs that passed through the region. The vegetating, delay-planted lowland palay might likewise be affected the same.
The vegetating, late- planted lowland 1st palay are in good condition across the region due to the availability of sufficient moisture.
Harvesting of late-planted, upland 1st palay had just started across the region; below normal yield is expected because of the passage of TCs which brought along storms and heavy rains. Crops were submerged under water and muds. The vegetating, late-planted lowland palay might also be affected by TCs during the month.
Harvesting of delay-planted upland 1st palay had just started across the region; good to normal yield is expected in Nueva Ecija due to favorable growing conditions. Likewise, in Cabanatuan, the rainfall amount during the month was favorable for the vegetating, delay-planted lowland palay. Meanwhile, below normal yield is expected in Zambales and Baler due to water logging and moisture stress, respectively.
Sufficient rainfall received during the month is favorable for the vegetating, delay-planted upland 1st palay in Tayabas and Ambulong.
Harvesting of late-planted, upland 1st palay had just started in most parts of the region; yield is expected to be good to normal in Coron, Cuyo, and San Jose. Below normal yield is anticipated in Pto. Princesa because crops experienced moisture deficiency during the critical stage of growth and development. Vegetating, delay-planted lowland 1st palay in most parts of the region were in good condition due to adequate moisture available during the month.
Harvesting of late-planted, lowland 1st palay in Albay and Catanduanes had just started; yield is expected to be good to above normal because crops were in good condition throughout the growing period. Standing crops in Masbate experienced moisture deficiency last month but somewhat recovered because of ample amount of moisture available during the month.
The standing, late-planted lowland 1st palay in vegetating stage experienced moisture stress across the region due to the insufficient moisture available during the month.
The standing vegetating late-planted lowland 1st palay experienced moisture deficiency throughout the region due to the insufficient moisture available during the month.
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.
Harvesting of delay-planted upland 1st palay in Zamboanga del Norte had just started: below normal is probable because of insufficient moisture available during maturity stage. The vegetating, late-planted lowland 1st palay which experienced moisture stress last month has now recovered due to sufficient moisture available during the month.
Harvesting of late-planted, upland 1st palay has 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 from planting to maturity. Sufficient moisture obtainable during the month favors the standing vegetating late-planted lowland 1st palay in Bukidnon, contrary to what is happening in Misamis Oriental, where standing crops experienced moisture stress due to very low rainfall received during the last two months.
Good to normal yield is expected this season for the harvestable delay-planted upland 1st palay across the region. It is because crops experienced favorable condition throughout their growing period.
The vegetating, late-planted lowland 1st palay experienced moisture stress due to insufficient amount of moisture available during the month.
Harvesting of June-planted lowland 1st palay has started in Surigao del sur: below normal yield is anticipated due to insufficient moisture experienced by the crops from vegetation up to maturity.
The vegetating, late-planted lowland 1st palay across the region experienced moisture stress due to scarcity of moisture available during the month and of last month.

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