Abdulwahid A. Saif^*(1) Hazem H. Al-Ashwal⁽¹⁾ and Mohammed A. Al-Khorasani⁽²⁾

(1). Northern Highlands Agricultural Research Station, Sanaa, Yemen.

(2). Natural Resources Center, Dahmar, Yemen.

(*Corresponding author: Dr. Abdulwahid A. Saif. E-Mail: amozaid@yahoo.com).

Received: 08/03/2020                               Accepted: 23/04/2020

Abstract

The impact of climate changes on two strategic crops; wheat and sorghum which are grown in the Northern Highlands (Sana’a), Central (Dhamar) of Yemen were studied using the AquaCrop model. The effectiveness of this model also was included in this study to simulate yield of these two strategic crops due to the expected climatic changes over the short term (2020-2030) and medium term (2040-2050) in comparison to the base years (1985-2005). The study was conducted under different irrigation systems in two different environments (Northern Highlands and Central Highlands), for this reason an average data for three climate models and average of the two scenarios (RCP 4.5 and RCP-8.5) to each model were used. Daily climate data (for 10 years past) associated with (T_max), (T_min), Relative Humidity (RH%), wind speed m/sec, radiation MJ/m².day, rainfall mm/day and crop yield and crop data were used for the calibration. Timing and amount of irrigation, soil water content and field management (level of fertilization and weed control) were the only calibrated parameters in order to obtain a relative correspondence between the actual and estimated values of yield by the program. The above data were collected from the weather stations located near the research farms which belong to Al-Erra Station –Sana’a and the Central Highlands Research Station-Dhamar, which were the selected sites of the study. They were different in terms of elevation above sea level, climatic and ecological nature. Some statistical indicators were used to assess accuracy and correctness at calibration of AquaCrop. Results of this study showed that the two crops will had a significant decrease in average yields, water productivity and water consumption at fixed concentration of CO₂. Growth period will also decrease as a result of high temperature in the three models over medium term 2040-2050 compared with the base years 1985-2005, this decrease is more significant in the scenario (RCP-8.5) compared to the scenario (RCP 4.5). Wheat yield and water productivity in Dhamar and Sana’a will be improved with the increased concentration of CO₂ over the medium term (2040-2050) under both irrigation and supplementary irrigation. For sorghum, it was noticed that yield and water productivity were decreased with the increased concentration of CO₂ in both scenarios and it was lower in Sana’a than in Dhamar due to the fluctuation of rain precipitation and drought occurrence, as sorghum, its cultivation depends­ on rain.

Key words: Climate change, Economic crops, Productivity.

Full paper in Arabic: PDF