A reliable and suitable irrigation (as surface or pressurized) can be improved agricultural production and irrigation efficiency. There are many studies to increase and manage irrigation efficiency [1-14]. A large number of considerations must be taken into account in the selection of an irrigation system. These will vary from location to location, crop to crop, year to year, and farmer to farmer. Table 1 shows a list of advantages and disadvantages of irrigation methods. Figure 1 shows global precipitation and the Reference evapotranspiration (ET 0) . The values of ET 0 for the Arabian Peninsula, Sahara, Gobi Desert, and the major areas in Australia range up to three meters per day. At latitudes greater than 40°S and 40°N, amounts of one meter and lower values can be found. Figure 2 shows total potential for rainfed agriculture . According to the Figure 2, 46% of the world is not suitable for rainfed agriculture because of climate changes and other meteorological conditions.
Valipour, M. (2016). Necessity of Irrigated and Rainfed Agriculture in the World. Irrigation & Drainage Systems Engineering, 2(2). https://doi.org/10.4172/2168-9768.s9-e001