الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 287 |  |  |
| | | from | 287 | | |
Abstract
Climate changes present major problem in different live activities especially agricultural sector. Climate changes causes an increase in the crop water requirements, and in turn affect the agricultural economy. The present study focuses on impact of climate changes, in the long term, on crop water requirements for various crops, cultivated in Zanzibar. It is an Island located offshore Tanzania mainland coast. Crop evapotranspiration (ETc) as well as crop water requirements (CWR) are estimated for rice, banana, tomato, watermelon and maize crops. For this purpose, climate data recorded by three selected stations; Kizimbani; Kisauni Airport and Selem station, during the period 1983 – 2013, is used. Based on the observed climate data, climate model is prepared, under representative concentration path way (RCP). RCP4.5, to predict climate conditions for the period 2020 – 2100 years. The linear scaling method is used to obtain corrected values of future temperature, rainfall, wind, relative humidity and sunshine hours using Climate Modeling Hydrologic (CMHYD) software. Using such corrected values and the other climate conditions, the CWR are estimated, for the considered crops, using CROPWAT 0.8 software. As a result, Zanzibar will be affected by climate extremes which lead to large climate variability with heavy precipitation and dry periods. Future temperatures are projected to rise in Zanzibar with increase of 1.3 to 2 0Cbby 2050 and 1.8 and 3.1 0C by 2100 related to the baseline year 2020. The average percentage increase in both ETc and CWR for the considered crops at 2100 year are about 24.6% , 7.72%,18.27%, 26.03% and 21.24%, respectively, related baseline 2020. The overall percentage increase, in both ETc and CWR, is 20.50 % for the all crops at the year 2100. Based on the current study results, and conclusions, the following recommendations are considered for minimizing the threats of climate variability and impact on crop water requirements in the study area and Tanzania in general. The need to search for appropriate technological methods to help mitigate the effects of climatic changes and variations, as well as planting tree fences to mitigate the effects of heat and reduce water losses resulting from evaporation when temperatures rise. Using alternative climate models under different scenarios to show behavior of climate data. Expansion of greenhouse farming for flowers, fruits and vegetables production is the best solution which can create the optimal climate conditions needed for plant growth which increase yield production per unit area. Greenhouses can protect high water losses in a cropped field due to the evapotranspiration