The Study Of Optimum Operation Of Qianjin Water Resource Area Of Daqing City

How to obtain the required water with the least economical expense is a major concern to each decision maker. However, the sustainable development and utilization of water resources should take many factors into account,not only economic issues but also social, environmental and other factors. The optimal operation of water source area is to search for an overall planning and optimizing decision with the least economic cost or the most economical use of water resources, in addition to generating little or no harm to the ecological environment.The normal operation of urban water sources, mainly supplied by groundwater in most area of northern China, ensures the sustainable socio-economic development of cities and towns. As the long-term exploitation of groundwater in Daqing Qianjin water source has led to the changes in groundwater cycle condition, the operation of production wells and the mining state, and caused a sequence of problems, such as the operating efficiency reduction, lower productivity, increased operating costs. Therefore, as an important measure to improve water productivity, reduce operating costs and to protect the underground water resources for sustainable development, the optimal operation of water management is bound to bring considerable socio- economic and ecological benefits. The current focus is taking a scientific measure and reasonable operation plans under the guidance of macroscopical groundwater dynamic monitoring, combined with the factors in groundwater development such as dynamic monitoring data, hydrogeological conditions, engineering techniques, water demand. Therefore, by adjusting well & water source exploitation mode timely, increasing groundwater yield, and at the same time decreasing the operation cost as further as possible, the aim of energy saving, consumption reduction, groundwater sustainable development, and environ-geological issue avoidance will be achieved.This study takes Qianjin water source field in Daqing City as a study case. After 40 year continuous exploitation, a large groundwater depression cone, up to 4000km2 in area, has formed in north Changgeng, Daqing area. Groundwater level in the cone center increases from 9m to 47.63m with an average speed of 0.96m each year. As the change of aquifer structure due to long-term groundwater exploitation, water outflow from single well and exploitation conditions change accordingly. To fulfill further development, new management mode must be suggested to make management measures in the new situation. The suggestion of the new modes can be carried out through making reasonable operation plans, like adjusting the water source exploitation mode, under the guidance of macroscopical groundwater dynamic monitoring combined with the factors in groundwater development such as dynamic monitoring data, hydrogeological conditions, engineering techniques, water demand and so on. On the basis above, to increase the groundwater yield and decrease the operation cost furthest and fulfill the aim of energy saving & consumption reduction, groundwater sustainable development, and environ-geological issue avoidance should be not so far. And this is the main purpose of this study.Making full use of the long term dynamic information and reconnaissance results, this study opens out the character of aquifer system, flow field information and formation regulations in Qianjin Water Source from the view of system & information theory on the base of character analysis of local groundwater system and groundwater resources. And this supplies a scientific basis for numerical simulation of groundwater flow.Based on hydro-geological data and groundwater chemical analysis data and the theory and methodologies of groundwater chemical dynamics in combination with limited pumping test data,some groundwater chemical index such as activity of componen(ta),mineral saturation index(β) are calculated and some hydro-geological parameters such as hydraulic conductively(K),transmissibility(T),actual speed of groundwater(U),specific velocity(V)and groundwater age(t)are also calculated.The above calculation results are beneficial to quantitatively recognize the local hydro-geological conditions and to attest that the confined aquifer of Taconic formation has good permeability and transmissibility and t good renewal ability because of the active groundwater movement. This case can supply not only hydro-geological parameters for groundwater resources evaluation but also quantificational basis for sustainable and reasonable development and management of groundwater resourcesThe author simulated the groundwater flow using groundwater numerical simulation technology in Qianjin source field, DaQing City, and ensure its simulation precision through the calibration and validation. By the water quantity balance analysis and calculation, the groundwater recharge rate is 4.7×104m~3/d under present exploitation, and less than the present groundwater exploitation. Groundwater level keeps the state of continuous drawdown. The groundwater overdraft reaches about 3000m3/d. In order to take up the balance of recharge and exploitation. It should be reduce groundwater extraction.The correlative analysis results of the parameter of extraction show, groundwater level, unit consumption, efficiency and the life of pumping wells are correlated with individual well yield. The rules as follows:①The individual well yield is positive correlation with dynamic water level, therefore, the extend trend of depression cone could be slower by reducing individual well yield.②The unit consumption is positive correlation with dynamic water level, therefore, in order to reduce unit consumption, the dynamic water level should be resumed.③There was a positive correlation between the single well exploitation quantity, outlet pressure and unit consumption. Therefore, maximum economic benefit could be obtained by controlling the groundwater level, determining the optimal allocation between the single well exploitation quantity, outlet pressure and unit consumption, mining the potential of water supply well with low energy consumption, decreasing the operating energy consumption of water source, which is management target of Qianjin water source.The exploitation of groundwater in Qianjin water source site is optimized against the current groundwater exploitation, in order to optimize the groundwater optimization, decreasing the operating consumption of the water source site. Considering single well yield, single well exploitation and single well loss, 7 exploitation schemes are designed.Under the exploitation conditions of scheme 1-4, the capacity of the water source are all 5×104m~3/d. Comparing the operating consumption of the water source site, the operating consumption are more different according to different exploitation distribution. Compared with every well being pumped in an average quantity, the power consumption of scheme 2 is the lowest, reducing 864 kwh a day, with the power saving ratio of 4.79%. The power saving ratio of scheme 3 and scheme 4 are separately 2.25% and 3.14%, while the power saving ratio of scheme 1 is only 1.96. Although the pumping capacity is increasing, it can be shown from the dynamic groundwater level curve of pumping wells that the groundwater is continuously decreasing, with an average annual drawdown 5.91-9.83m. The operation of the water source site is not stable, and long time exploitation will definitely cause the depletion of groundwater resources, so these schemes can not be adopted.Considering about water resource consumption, the less water resource been exploited the more electricity could be saved. According to the water requirement in the supply area, it is better to keep the water exploiting quantity in water source site 4.5×10~4m~3/d. in that way can we keep the site run long-term and stable. The exploiting water quantity in each well is assigned according to the optimizing scheme. 816kWh electricity can be saved in that case, which is 5.03% be saved.When the yield increase to 5.0×10~4 m~3/d in water source site. Yield of water can be assigned according to the second scheme. 684.0kWh electricity can be saved per day when the exploiting quantities are same each well. The scheme seven is suggested to be best exploiting scheme in Qianjin water source site. The optimum single well exploiting quantity is assigned according to this scheme. And the optimum exploiting quantity is 3.5×10~4-4.0×104m~3.The optimum single well exploiting quantity is assigned according to scheme six or scheme seven.The optimum operation of water source site is carried out by the measurements next. Such as strengthen the integrate management in the site, adjust the distribution of exploitation, exploit groundwater reasonable, improve the forecast work, program total exploiting quantity reasonable using the manner"supply groundwater in dry period by high water period", control groundwater level depress, optimize the exploitation layout, reduce the cost of water exploitation, extend the operational life of exploiting wells and strengthen the dynamic monitoring in water source site.