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 2020

OVERVIEW

Harvesting of lowland and upland 1st palay had just started in some parts of the country; good to normal yield is expected in CAR, Nueva Ecija, Baler, Casiguran, Infanta, Tayabas, Legaspi, Catanduanes, Catarman, Catbalogan, Bukidnon, Davao and Surigao del Sur. In Ilocos Norte, Basco and Tuguegarao below normal yield is anticipated because crops suffered moisture stress during the critical stage of growth and development.

Meanwhile, the standing delay-planted lowland and upland 1st palay crops planted in June and lowland 1st palay planted in July are faring well in Ilocos region, CAR, Tuguegarao, Bataan, Nueva Ecija, Baler, Casiguran, CALABARZON, Coron, Cuyo, Romblon, San Jose, most of Region V, Panay Island, Mactan, Eastern Visayas, Dipolog, El Salvador, Malaybalay, Davao, and ARMM. However, in Calapan, Pto Princesa, Dumaguete and Zamboanga del Sur, palay crops suffered moisture stress because of the minimal rainfall received in those areas.

The weather systems that affected the country during the month were the Southwest (SW) monsoon, the intertropical convergence zone (ITCZ), easterlies, low pressure areas (LPAs), localized thunderstorms and the passage of six (6) tropical cyclones (TCs), namely: Tropical Storm (TS) “Enteng” (Aug 8-9), Tropical Depression (TD) “Ferdie” (Aug 9-10), Tropical Depression(TD) “Gener” (Aug 10), Tropical Depression (TD) “Helen” (Aug 17), Severe Tropical Storm (STS) “Igme” (Aug 21-22) and Typhoon (TY) “Julian” (Aug 28-31). These TCs did not make landfall. Nonetheless, TS “Enteng”, TD “Ferdie” and TY “Julian” slightly enhanced the Southwest monsoon which brought heavy precipitation in some parts of western Luzon.

REGIONS

Harvesting of upland 1st palay had just started in Ilocos Norte; below normal yield is expected because crops suffered moisture stress during the critical stage of growth, although crops recovered during the reproductive stage. The standing, delay-planted upland 1st palay in Ilocos Sur and Pangasinan, as well as the lowland 1st palay due this October across the region are in good crops condition because of sufficient moisture during the month.
Harvesting of upland 1st palay had just begun in Cagayan Valley; below normal yield is expected because crops suffered moisture deficiency during its critical stage of growth and development. During the month, the standing, newly-planted lowland 1st palay due this coming October in Tuguegarao is in good crops condition because of sufficient rainfall received.
Harvesting of upland 1st palay had just begun across the region; good to normal harvest may be expected because of the sufficient rainfall received by the crops from planting to maturity. The standing, newly-planted lowland 1st palay, as well as the late-planted, upland 1st palay were in good crops condition because of adequate moisture available during the month.
Harvesting of upland 1st palay has commenced in Nueva Ecija and Aurora province; the probability of good to normal yield is expected this season because the crops were in good condition. The standing late-planted, upland 1st palay in Bataan, and Aurora provinces and lowland 1st palay planted last month in Bataan and Nueva Ecija are currently in good crop condition due to the sufficient rainfall received in those areas during the month.
Harvesting of lowland 1st palay in Infanta and upland 1st palay in Tayabas is now on-going; good to normal yield is expected because the crops were in good condition from planting to maturity. The standing late-planted upland 1st palay in Tayabas and lowland 1st palay in Batangas and Tayabas are faring well because of sufficient rainfall received in those areas during the month.
During the month, due to sufficient moisture available, the standing delay-planted, upland 1st palay as well as the newly-planted lowland 1st palay in most parts of the region experienced good crops condition except in Calapan and Pto. Princesa.
Harvesting of lowland 1st palay in Legaspi and Catanduanes had just begun: good to normal yield is anticipated because crops were in good condition from planting to maturity. Likewise, the vegetating delay-planted, lowland 1st palay in most parts of the region are in good condition because of the sufficient moisture available during the month.
The standing newly-planted lowland 1st palay in Cebu is in good crops condition unlike in Dumaguete, due to lesser amount of rainfall available during the month, rice crops experience moisture stress.
Sufficient rainfall received during the month favors the standing delay-planted upland 1st palay now in reproductive stage as well as the newly-planted lowland 1st palay due this coming October.
Harvesting of lowland 1st palay in Catarman and upland 1st palay in Catbalogan has now started; good to normal yield is expected because crops were in good condition throughout the growing season. Likewise, the standing late-planted, lowland 1st palay in Catarman, Catbalogan and Tacloban, the late-planted upland 1st palay and the newly-planted lowland 1st palay due on October in Catbalogan and Tacloban are faring well.
The standing late-planted, upland palay in Zamboanga del Norte are in good condition unlike in Zamboanga del Sur, where the crops suffered moisture stress due to the minimal rainfall received during the month.
Harvesting of upland 1st palay in Bukidnon had just begun; good to normal harvest is expected this season because crops were in good condition from planting to maturity. The standing late-planted, upland 1st palay and the newly-planted, lowland 1st palay due this coming October in Bukinon and Misamis Oriental are in good condition because of sufficient moisture available during the month.
Harvesting of upland 1st palay had just started across the region; good to normal yield is expected because crops were in good crop condition throughout its growing period. Likewise, the standing late-planted, upland 1st palay is faring well
The possibility of planting rice crops in any part of the region is low because of the minimal rainfall received in the area.
Harvesting of lowland 1st palay had just started in Surigao del Sur; good to normal yield is anticipated because crops experienced sufficient moisture throughout its growing season. The standing late-planted, lowland 1st palay across the region is faring well.
The newly-planted, lowland 1st palay due this coming October are in good crop condition due to the sufficient moisture available during the 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