Drought Monitoring Systems

Rainfall Analysis

The NMSA of Ethiopia regularly produces a 10-day bulletin that gives analysis of rainfall based on the long-term average or normal. This bulletin is circulated to a wide range of users, ranging from local development agents to the decision-makers at national level. The rainfall analysis includes both qualitative and quantitative evaluations. The onset of a rainy season is reported as early, normal, or late onset. The rainfall distribution is expressed as whether it is deficient or excess, erratic or even. The rainfall is compared with the normal by computing the percentage deviation (D). Depending on the range of D, the area is considered to have more (D > 125), the same (75 < D<125), insufficient (50 <D <75), or below average (D < 50%) rainfall. If drought continues for consecutive season or years, it signals an alarming situation.

Normalized Difference Vegetation Index

The normalized difference vegetation index (NDVI) is a satellite data-based index widely used to monitor vegetation and drought conditions. The detailed description of NDVI is provided in chapters 5 and 6. There are few organizations that provide the NDVI analysis. However, the NMSA produces a regular 10-day bulletin regarding NDVI variation that compares the current vegetation condition with normal or last-year conditions. The bulletin is distributed to higher officials and NGOs engaged in early warning activities.

Crop Monitoring

Crop performance during the growing season is monitored by the members of the National Early Warning Committee (NEWC). Land preparation, planting, and cropping pattern are monitored based on the area prepared for cultivation as compared with the normal and last-year equivalents. Moreover, area planted is compared with last year and normal year. Dates of planting are compared with the seasonal crop calendar to identify any delay in planting. Crop conditions during specific phenological phases are monitored, and poor/very poor crop conditions are also identified. Based on such monitoring, recommendations are made for alleviating any crop damage. The availability of inputs, such as fertilizers, pesticides, and improved seeds and the financial ability of the farmer to use the inputs is explained in the monitoring report. Finally, estimates on crop productions are made and compared with the last year and also with a normal year.

Water Balance Method

A crop water balance method can also be used to monitor crop performance and estimate its production. The full methodology and the table used in the computation are explained by Frere and Popov (1979). The criteria used to estimate the quality of production is presented in table 17.1. The NMSA uses this procedure to analyze the current crop situation.

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