Agricultural Drought Assessment Using Various Drought Indices In East Shewa Zone, Central Ethiopia

Abstract

Drought is one of the natural hazards that will occur because of the deficiency of water or moisture in the area, which leads to famine and total disaster. Drought collectively reviewed in four perspectives i.e. Metrological, Agricultural, Social, and Hydrological. The primary objective of this research is to assess the spatial extent, and frequency of agricultural drought in East Shewa Zone. This study employed various drought indices in two categories (single and combined). Precipitation condition Index (PCI), Temperature Condition Index (TCI), Vegetation Condition Index (VCI), and Soil Moisture Condition Index (SMCI) were categorized as single drought indicators. Whereas, three drought indices namely Optimized Vegetation Drought Index (OVDI), Vegetation Health Index (VHI) and Scaled Drought Condition Index (SDCI) grouped as combined drought indices. The results of both single and combined drought indicators were validated by employing Standardized Precipitation Index (SPI) using five time scales( one, three, six, nine and twelve months respectively). Bringing all the single drought indices to a common platform using Empirical weight method outperformed constrained optimization method. Interestingly, results showed distinct drought conditions for different indices and varies between Kiremt (rainy) and Bega (non-rainy) seasons. The scaled single condition indices and raw drought indicators showed maximum correlation coefficients of 0.764 and 0.494 respectively. The combined agricultural indices and single condition indices also showed minimum correlation of 0.12 and -0.25 respectively. It is evident that PCI and SDCI has showed maximum correlation of 0.764 and 0.741 respectively. Moreover, PCI provided better results with shorter SPI timescales. The overall result of single and combined agricultural drought indices identified Fentale as severe drought wereda followed by ATJK, Boset, Adama and Gimbichu. Therefore, comprehensive method between in situ and remote sensing drought indices with multiple parameters are effective for agricultural drought assessment.

Drought Is One Of The Natural Hazards That Will Occur Because Of The Deficiency Of Water Or Moisture In The Area, Which Leads To Famine And Total Disaster. Drought Collectively Reviewed In Four Perspectives I.E. Metrological, Agricultural, Social, And Hydrological. The Primary Objective Of This Research Is To Assess The Spatial Extent, And Frequency Of Agricultural Drought In East Shewa Zone. This Study Employed Various Drought Indices In Two Categories (Single And Combined). Precipitation Condition Index (Pci), Temperature Condition Index (Tci), Vegetation Condition Index (Vci), And Soil Moisture Condition Index (Smci) Were Categorized As Single Drought Indicators. Whereas, Three Drought Indices Namely Optimized Vegetation Drought Index (Ovdi), Vegetation Health Index (Vhi) And Scaled Drought Condition Index (Sdci) Grouped As Combined Drought Indices. The Results Of Both Single And Combined Drought Indicators Were Validated By Employing Standardized Precipitation Index (Spi) Using Five Time Scales( One, Three, Six, Nine And Twelve Months Respectively). Bringing All The Single Drought Indices To A Common Platform Using Empirical Weight Method Outperformed Constrained Optimization Method. Interestingly, Results Showed Distinct Drought Conditions For Different Indices And Varies Between Kiremt (Rainy) And Bega (Non-Rainy) Seasons. The Scaled Single Condition Indices And Raw Drought Indicators Showed Maximum Correlation Coefficients Of 0.764 And 0.494 Respectively. The Combined Agricultural Indices And Single Condition Indices Also Showed Minimum Correlation Of 0.12 And -0.25 Respectively. It Is Evident That Pci And Sdci Has Showed Maximum Correlation Of 0.764 And 0.741 Respectively. Moreover, Pci Provided Better Results With Shorter Spi Timescales. The Overall Result Of Single And Combined Agricultural Drought Indices Identified Fentale As Severe Drought Wereda Followed By Atjk, Boset, Adama And Gimbichu. Therefore, Comprehensive Method Between In Situ And Remote Sensing Drought Indices With Multiple Parameters Are Effective For Agricultural Drought Assessment.