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 TermsThe 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
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
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:
|> 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 2021
Heavy rainfall that caused flooding may have also hindered the establishment or land preparation activities for 2nd planting season of corn in Ilocos Region, CAR, Cagayan Valley, Central Luzon, CALABARZON, MIMAROPA and Bicol Region. In these regions (except MIMAROPA and Bicol Region), heavy rainfall possibly damaged the 3rd planting season corn in the vegetative stage. The same may have happened to the 2nd planting season corn, curently in flowering stage, in Negros Occidental, Iloilo, Eastern Visayas, Zamboanga Peninsula, Northern Mindanao, and CARAGA. Generally, and for surviving crops in areas affected by heavy rainfall, the moisture for the month had been sufficient for the rainfed crops in Catanduanes, Camarines Sur, Negros Occidental, Bohol, Leyte, Zamboanga Sibugay, Misamis Oriental, Lanao del Norte, Davao del Norte, Compostella Valley, and Lanao del Sur.
The weather systems that affected the country during the month were the Southwest (SW) monsoon, localized thunderstorms, low pressure areas (LPAs), easterlies, intertropical convergence zone (ITCZ), and the passage of three (3) tropical cyclones (TCs), namely: Tropical Depression (TD) “LANNIE” (Oct. 4 – 6), Severe Tropical Storm (STS) “MARING” (Oct. 8 – 12) and Tropical Depression (TD) “NANDO” (Oct. 9). TD “LANNIE” made landfall and brought heavy rainfall, which caused flooding in MIMAROPA and Region 6 while STS “MARING” did not landfall but enhanced the Southwest monsoon which brought moderate to heavy rainfall and caused flooding and landslide in Region 1, Region 2, Region 3, MIMAROPA, CARAGA and CAR with an estimated cost of damage to agriculture amounting to ₱3,267,218,527.47 based on NDRRMC Sitrep no. 15 on STS “MARING” (2021).
Rainfall assessment for the month showed that near to above normal rainfall conditions were experienced in most parts of the country except for Central Luzon, where below normal rainfall conditions were observed.
Establishment or land preparation stage for the 2nd planting season corn has generally started, however, the occurrence of heavy rainfall might have hindered the activity. The 3rd planting season corn is in the vegetative stage, and thus, may have also been affected by heavy rainfall.
Establishment or land preparation activity for the 2nd planting season corn has also started, however, heavy rainfall may have adversely affected the activity. Corn in the 3rd planting season is in the vegetative stage, and thus, may have also been affected by heavy rainfall.
Establishment or land preparation activities for the 2nd planting season corn have started; however, the occurrence of heavy rainfall may have hampered the farming activity. Meanwhile, the 3rd planting season corn crops that are in the vegetative stages, might have also been affected by heavy rainfall.
Establishment or land preparation activities for the 2nd planting season corn has generally started, however, heavy rainfall events might have hindered these farming activities. Corn in the 3rd planting season is in the vegetative stage, and thus, may have also been affected by the heavy rainfall occurrence.
Establishment or land preparation activities for the 2nd planting season corn has also started, however, heavy rainfall event might have hindered the activity. Corn in the 3rd planting season is in the vegetative stage, and thus, may have also been adversely affected by heavy rainfall.
Establishment or land preparation stage for the 2nd planting season corn has generally started, however, heavy rainfall activity may have hindered the activity.
Potential damage to the 2nd planting season corn, currently in flowering stage, may have also occurred because of heavy rainfall.
Additionally, the 2nd planting season corn in flowering stage may have also been damaged by the occurrence of heavy rainfall.
The monthly rainfall is sufficient for the rainfed crops in Davao del Norte and Compostella Valley, excess in Davao Oriental, and inadequate in Davao del Sur.
For the surviving crops, moisture for the month is generally sufficient for all stages.