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 OCTOBER 2020

OVERVIEW

Harvesting of late-planted lowland 1st palay and late-planted upland 1st palay is ongoing in some parts of the country. Good to normal yield is expected in CAR, Nueva Ecija, Aurora, Baler, Casiguran, Infanta, Tayabas, Romblon, Cuyo, Coron, San Jose, Legaspi, Catanduanes, Catarman, Catbalogan, Tacloban, Zamboanga del Norte, Bukidnon, El Salvador, Davao, Surigao del Norte, and Surigao del Sur. Meanwhile, below normal yield is possible in Zambales, Dumaguete, Tagbilaran, Pto. Princesa, Calapan and Zamboanga del Sur since crops suffered from moisture stress during the critical stage of growth and development.

The vegetating lowland 1st palay planted in July is faring well in CAR, Bataan, Nueva Ecija, Tayabas, Coron, Cuyo, Romblon, San Jose, Panay Island, Mactan, Catbalogan, Tacloban, El Salvador, Malaybalay, and ARMM. Meanwhile, palay crops in Zambales, Batangas, Calapan, Dumaguete, Tagbilaran, Pto. Princesa, Dumaguete and Zamboanga del Sur suffered moisture stress due to insufficient rainfall.

The weather systems that affected the country during the month were the Southwest Monsoon (SW), inter-tropical convergence zone (ITCZ), low pressure areas (LPAs), localized thunderstorms, easterlies, and the passage of five (5) tropical cyclones (TCs) named Tropical Storm (TS) “Nika” (NANGKA), October 11-12; Tropical Depression (TD) “Ofel”, October 13-16; Typhoon (TY) “Pepito” (SAUDEL), October 19-22; TY “Quinta” (MOLAVE), October 23-27 and Super Typhoon (STY) “Rolly” (GONI), October 29-November 3. Among the five TCs, only TS Nika did not make landfall but it enhanced the southwest monsoon. The other four TCs made multiple landfalls and brought heavy to intense rainfall that caused floods and landslides over Regions II, III, NCR, CALABARZON, MIMAROPA, Bicol Region, Regions VI, VII, VIII, XI and Cordillera Administrative Region (CAR), resulting to severe damages to infrastructure, agriculture and a number of casualties according to the National Disaster Risk Reduction and Management Council (NDRRMC) situational reports.

REGIONS

Harvesting of late-planted, upland 1st palay is ongoing in the region. Below normal yield is expected because of water logging brought by tropical cyclones that hit the region. In Ilocos Norte, below normal yield is expected due to the shortage of rainfall during the critical stage of growth. For the same reason, major yields loss is also possible in Pangasinan.
The vegetating lowland 1st palay planted in July suffered from moisture stress due to insufficient rainfall in Tuguegarao and Batanes.
Harvesting of late-planted upland 1st palay is ongoing across the region; good to normal yield may be expected because of adequate moisture experienced by the crops throughout its growing season. Likewise, the vegetating lowland 1st palay as continued to experience good crops condition because of sufficient moisture available during the month.
Harvesting of July-planted, lowland 1st palay is ongoing in Nueva Ecija and Aurora provinces, where good to normal yield is expected because crops were in good condition during the entire growing season. Meanwhile in Zambales, below normal yield is anticipated due to insufficient rainfall during the critical stage of growth and development.
Harvesting of late-planted lowland 1st palay in Infanta and late-planted upland 1st palay in Tayabas is on-going; good to normal yield is anticipated because crops were in good condition from planting to maturity. The vegetating lowland 1st palay planted last July in Tayabas are faring well because of sufficient rainfall received during the month.
Harvesting of delay-planted upland 1st palay in most parts of the region is ongoing; good to normal yield is anticipated because crops experienced good crops condition from planting to maturity except in Calapan and Pto. Princesa. However, due to the effect of tropical cyclones, the mature plants that were not harvested earlier may have been damaged.
Harvesting of delay-planted lowland 1st palay in most parts of the region is ongoing: good to normal yield is anticipated because crops continued to experience good crops condition from planting to maturity. However, due to the effect of tropical cyclones, the mature plants that were not harvested earlier may have been damaged.
The ample amount of rainfall received in Cebu keeps the vegetating, lowland 1st palay planted last July in good shape. However, in Dumaguete and Tagbilaran, below normal yield is expected due to the insufficient rainfall.
Harvesting of delay-planted upland 1st palay is ongoing; good to normal yield is anticipated this season. The insufficient rainfall during the month may slightly affect the vegetating lowland 1st palay.
Harvesting of delay-planted lowland 1st palay across the region and the delay-planted upland 1st palay in Catbalogan and Tacloban is ongoing; good to normal yield is expected because crops were in good condition from planting to maturity. However, due to the effect of tropical cyclones, the mature plants that were not harvested earlier may have been damaged.
Harvesting of delay-planted upland 1st palay in ongoing; good to normal yield is expected in Zamboanga del Norte because crops were in good condition from planting to maturity, on the other hand in Zamboanga del Sur, below normal yield is anticipated because crops experienced moisture deficiency during the critical stage of growth.
Harvesting of July-planted, lowland 1st palay is ongoing in the province of Bukidnon; good to normal yield is anticipated this season due to sufficient rainfall during the periods of planting to maturity. Meanwhile, there may be no palay harvests in Misamis Oriental due to insufficient rainfall.
Harvesting of delay-planted upland 1st palay is ongoing across the region; good to normal yield is expected because crops were in good condition throughout the growing period.
Rice planting is hindered by the persistent lack of rainfall.
Harvesting of delay-planted lowland 1st palay is ongoing across the region. Good to normal yield is expected because of sufficient rainfall during the critical stage of growth and development.
Harvesting of delay-planted lowland 1st palay is ongoing across the region. Good to normal yield is expected because of sufficient rainfall during the critical stage of growth and development.

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