Computer Control And Management Of Water Resources For Agriculture

Irrigation in China has a very long history with documented development of large scale irrigation schemes. China had approximately 48 million hectares of irrigated area by 1992. This includes 144 large scale irrigation district covering 7.9 million hectares, 5,198 medium size irrigation districts covering 13.3 million hectares and numerous small reservoirs, ponds, and pumping schemes. Large and medium systems serve about 47% of total irrigated area in the country; 26% is irrigated by tube wells managed directly by fanners.With a population exceeding 1.2 billion, China is extremely concerned with feeding its population; therefore irrigation is critically important as 65% of food grains, 75% of cash crops and 90% of vegetables produced on irrigated land. In addition, irrigation districts supply 70-80% of drinking water for people and livestock in rural areas. Majority of the existing medium and large systems were developed during 1950s, 1960s and 1970s. A number of these schemes were large pump-based systems lifting water from rivers and other surface water sources. Currently the ageing degree of irrigation district is aggravating. In addition because of the backward method of management, the utilization factor is low.The need for higher production in agriculture and the restrictions on flexibility of water in frequency, rate, and duration are the main reasons behind the need for better-controlled and automatic irrigation.This paper presents the design of automated computer controlled irrigation system. It includes the mathematical programming model for optimizing water resources dispatch from the pumping stations, which is the guidance for the development of control process. The control system design is divided into two levels. The local data collection and transmission is the 1st level, it is functioning by sensors and PLCs (Programmable Logic Controller). This task is dedicated to the remote stations. The 2nd level is the system functions of control, monitoring and management operations, which is dedicated to the central station. The management and control utilize centralized control method.