| At present,China’s agricultural water consumption accounts for more than70%of the total water consumption,of which 91%is used for irrigation.However,due to the influence of aging irrigation equipment,backward irrigation technology and improper water management in irrigation areas,the utilization coefficient of irrigation water in China is only about 0.55,only accounting for 70%of that in developed countries.At the same time,with the rapid development of social economy,the competition between industrial water,urban water,environmental water and agricultural water is increasingly fierce,which leads to the increasingly serious contradiction between the supply and demand of irrigation water.Therefore,the scientific management of irrigation water and the establishment of the optimal allocation model of irrigation water are of great significance for the efficient utilization of the limited water resources in the irrigation area and the promotion of the sustainable development of the ecological environment and economy in the irrigation area.Taking Qingan peace irrigation area in Heilongjiang province as the research object,through the whole irrigation channels real-time water monitoring section water,irrigation channels construction basic data collection,the cognizance of the paddy field irrigation area is controlled by different lateral canal and the basic law of rotational irrigation in irrigated areas,irrigation channels Mike11HD model is established and simulated test and verify.With the three basic annual types of rich water year,plain water year and dry water year,water-saving irrigation and regular flood irrigation are two irrigation methods,different development stages of the 6 kinds of bubble in rice field period,turning-green stage,tillering stage,the jointing-booting stage of ratooning buds,earing,context,the amount of water needed to main canal irrigation system maximum water design flow of 11.887 m~3/s in the lateral canal maximum under the condition of water conveyance capacity,analysis and calculation of 36 kinds of situations rotation irrigation regularity and rotational irrigation period in the irrigation area.Through further simulation and analysis,the rotation irrigation law and cycle of irrigation in different situations are verified in irrigated areas.The main research results are as follows:(1)the main basis of channel linear infiltration recharge is the channel infiltration coefficient.Under the non-static condition,the measured flow rate of the upstream and downstream sections of representative canal sections is adopted,and the infiltration coefficient of each measured section is obtained by calculating the difference of the measured flow rate of the upstream and downstream sections.According to the analysis of the measured results,the infiltration coefficient of the main channel is 0.28%,and that of the branch channel is 0.22%.(2)the position of the water crossing section measured by the channel is in the downstream channel section of the gate,and the flow pattern can be roughly similar to the uniform flow of the open channel.The relationship between the measured flow rate and the downstream water level is analyzed.The correlation coefficient between the flow coefficient of the intake gate and the square root of the difference between the upper and lower water levels reached 0.80.It can be seen from the results that the gate flow coefficient has a power function relation with the square root of the difference between upper and lower water levels,so the greater the difference between upper and lower water levels,the smaller the gate flow coefficient and the greater the water energy loss.In the actual work of the gate,the smaller the opening of the gate is,the greater the difference of water level between upper and lower reaches is,and the greater the loss of water head is,resulting in the smaller the gate coefficient is.The ratio of the actual opening degree of the gate to the difference between the upper and lower water levels is called the relative opening degree of the gate.By analyzing the data of the flow coefficient of the gate and the relative opening degree of the gate,the correlation coefficient is 0.87,that is,there is a positive linear correlation between the flow coefficient of the gate and the relative opening degree.(3)a comprehensive dimensionless number of the influence of roughness reaction on flow resistance,whose size varies with the roughness of boundary surface.The model adjusts the channel roughness through the measured data of dry and branch canals in the irrigation area.The roughness n of different branch canals is between 0.016 and 0.018.(4)according to the different water demand quota in different scenarios of the paddy field,the maximum design flow rate of water from the main canal was11.183 m~3/s through simulation analysis,and the rotation irrigation cycle and scheduling scheme of the paddy field under different water demand quota were obtained under the condition of each branch canal’s maximum water delivery capacity.The water demand quota is 140 mm,and the cycle of canal irrigation is8.9 d.The water demand quota is 130 mm,and the cycle of canal irrigation is 8.3d.The water demand quota is 120 mm,and the cycle of canal irrigation is 7.6d.The water demand quota of 110 mm is 7.0 d.The water demand quota is 100mm and the cycle of canal irrigation is 6.5 d.The water demand quota of 90 mm is 5.7 d.The water demand quota is 80 mm,and the cycle of canal irrigation is5.1 d.The water demand quota is 70 mm,and the cycle of canal irrigation is 4.5d.The water demand quota is 60 mm,and the cycle of canal irrigation is 3.8d.The water demand quota is 50 mm,and the cycle of canal irrigation is 3.2d.The water demand quota is 40 mm,and the cycle of canal irrigation is 2.6d.The water demand quota is 30 mm,and the cycle of canal irrigation is 1.9 d.(5)the cycle of rotation irrigation under different conditions in the irrigated areas was obtained through model simulation research,and the cycle of rotation irrigation was all smaller than that of different growth periods in the rice field,so the cycle of rotation irrigation obtained met the irrigation water demand of the rice field.Considering that the late acquisition of water resources in the lower reaches of the irrigated area during the peak period of rice use may have an impact on rice yield,groundwater can be properly extracted in the lower reaches of the irrigated area for irrigation. |
