Study On Multi-reservoirs Optimal Operation Of Manas River Irrigation Area

Serious water shortages restrict the development of socio-economic and the improvement of people's living standards in Northwest China. With the development of our country's economy, the continual increasing of water consumption aggravates progressively the conflict between supply and demand of water; water shortage conflicts have raised tothe primary contradiction of water resources. The Manas river irrigation area locates at southern margin of Junggar basin of the northern foot of the Tianshan Mountain, which is a typical oasis and irrigated agricultural area. Main irrigation water resources are river water, spring water and well water, agricultural production entirely depend on water diversion irrigation. There are two main reasons which can not satisfy the demand of irrigation water: one is that the irrigation area water resources quantity was finited, the other is that the reservoirs failed to exercise original role after many years operation. Multi-reservoirs optimal operation model was established in accordance with problems of water resources shortage and production needs of Manas river irrigation area, and that has important significance to alleviate contradiction between water supply and water demand, improve water use efficiency and guarantee the production need of irrigation area.The main contents and results are summarized as follows:(1) Based on runoff data of hongshanzui hydrologic station,principle of water diversion and《Management Statute of Manas River Basin》,the total water supply quantity was analyzed. The total water supply quantity of P = 50% and P = 75% of the Manas river irrigation area is 1,411,442,000 m3 and 1,322,709,000m3, respectively. This article selected 2000 as the current year, the condition of using water was analyzed. The total water consumption is 1,351,364,700 m3, in which agricultural water is 1,109,681,000 m3, it is 82.11% to the total water consumption. The water consumption of domestic, industrial, livestock and fisheries, special and ecology is 32,580,000m3, 48,020,000m3, 4,103,700 m3, 90,100,000 m3 and 66,880,000 m3,respectively; In view of the total water, the total water supply quantity of P = 50% can satisfy the requirements of water demand, volume of water shortage of P = 75% is 28,655,700 m3. Because of the ununiformity of incoming water and the difference of water demands in each month, water scarcity occurs in April, June and July, but the excess water occurs in August, September and October.(2) By using large scale system decomposition- coordination theory and dynamic programming, the model of multi-reservoirs optimal operation was established according to actual situation of irrigation area. Large scale system decomposition-coordination and discrete differential dynamic programming were employed for solving the model. Meanwhile, the results were analyzed. The conclusions can be reached through solving the model of multi-reservoirs optimal operation: The contradiction of supply and demand water was alleviated and the water supply demand deficit was controlled in the range of -43,694,100 m3 ~ 631,500 m3 after optimization operation of multi-reservoirs. The guarantee rate of water supply of P = 50% and P = 75% is respectively 95.1% and 93.5%, which can better ensure agricultural production of irrigated areas; Reservoir operation under the low water level in the wet season (in July and august) can effectively play the role of flood control and reducing the loss of reservoir, Meanwhile, reservoir control approach also could guarantee water of irrigation area furthest, and harmonize the contradiction of flood control and profit to some extent.(3) Under the limit of total water supply quantity and project scale in irrigation area, the difference between supply and demand was effectively reduced after the multi-reservoirs optimal operation. It has advantageously guaranteed production need of the irrigation area, but the conflicts still exist between supply and demand of water, water shortages remain a bottleneck of hindering the development of irrigated area.