Abstract
ETo is important parameter in determination of crop water requirement and in irrigation scheduling. The absence of rainfall during four to six months of the year affects crop production. Study was undertaken in Jimma zone, Southwestern Ethiopia, with the objective of evaluating and characterizing the reference evapotranspiration and mapping for planning and management options for Jimma Zone. The study was undertaken at 22 sites of which 14 being from Jimma zone and the remaining eight sites were from around the vicinity of study area. The ETo was estimated using Penman–Monteith method in CROPWAT 8.0 software with monthly datasets of 22 stations for the period of 31 years. The results of ETo were further analyzed by means of geo-statistical tools in R software using gstat package. Maps were created using ordinary kriging combined with regression method. The results have shown that the ETo, have shown moderate to greater variability. The high annual and monthly ETo values were observed around the extreme eastern tip, extreme southern tip and north western tip. In contrary low ETo values were observed in southeastern and western regions. March (4.61 mm/day) and July (2.97mm/day), respectively, presented the highest and the smallest ETo. The ETo for Jimma zone is a good indicator and benefits to farmers to help in planning the water resources of the area for best irrigation water management practices.
Highlights
Water is one of the most important inputs essential for the crop production because plants require water for growth and tissue expansion
Improved water management in agriculture depends on reliable estimates of water use by plants [4]
The first step in estimation of crop water requirement is determination of evaporative demand of atmosphere, which is expressed as the reference evapotranspiration [5]
Summary
Water is one of the most important inputs essential for the crop production because plants require water for growth and tissue expansion. Direct measurement is both inconvenient and expensive For this reason, many methods have been developed for estimating ETo from climate data [6, 7]. In 2016/17 during dry years, International Journal of Natural Resource Ecology and Management 2021; 6(3): 108-115 hundreds hectares of crops and animal forage were devastated due to the lack of supplemental irrigation [11]. Geo-statistical interpolation methods such as ordinary kriging are a promising tool to overcome this problem It generates both spatial autocorrelation and prediction map depending up on semi-variogram and distance [13]. To achieve effective planning on irrigation water management, accurate information is needed for potential evapotranspiration. The objective of this study was to analyze and characterize the ETo and mapping for planning and management options for Jimma zone
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