ABSTRACT
Agriculture is the foundation of a country while irrigation is the spirit of agriculture. —King of Han Wu, 155−74 BC
Very recent archeological evidence [62] in site Ohalo II in Syria found more than 90,000 plant fragments from 23,000 years ago. This indicates that, settled agriculture began over 10,000 years earlier than previously thought. Previous to this, the settled agriculture was known to have started around 10,000 years back [1-3]. Irrigated agriculture started at Mesopotamia Lowland around 7000-6000 BC [3,4]. An overwhelming proportion of early agriculture took place along the river banks, deltas, and flood plains, where there was plenty of water for agriculture [4]. Notwithstanding that, these may not be strictly defined as irrigation, as they were dependent on nonprecipitation sources for agriculture. Almost all early, great civilizations flourished along the great rivers. With time and increases in populations, humans started using engineering skills to block rivers, create reservoirs and channels, and divert water to areas of interest. Yet, until 1800, irrigation was a modest 8 million hectares (Mha). However, irrigated areas increased swiftly to reach 50 Mha by 1900 and 95 Mha by 1940. From 1940 to 2000, which can be called the irrigation era, irrigated areas increased to around 275 Mha by conventional estimates. During this period, informal irrigation (e.g., groundwater, small reservoirs, minor embankments, and tanks) flourished. After 1950, farmers began tapping groundwater on a large scale, as powerful diesel and electric pumps became available [5]. In the early 1960s, for example, groundwater irrigation was insignificant. In substantial areas of China and India, groundwater levels were falling by 13 m/ year [6]. However, by 2000, groundwater irrigation was nearly 60% of the total irrigated areas in India as a result of over 19 million bore wells sunk across the country [7].
