【作者】 夏珊珊；

【导师】 孙志林；

【作者基本信息】 浙江大学 ， 水工结构工程， 2010， 博士

【摘要】 沿海平原地区人口密集,经济发达,但水资源往往并不充沛,资源性缺水伴随着水质性缺水,成为制约当地经济社会发展的主要因素之一。为满足当地经济社会可持续发展的要求,需合理利用域内有限的优质水资源,并从域外引水以根本解决资源性缺水问题。综合考虑经济效益、制水输水成本和水量均衡分配等目标及其制约关系,构造了一个新的非线性总目标函数。将3个目标函数有机地组合起来,以可供水量、需水量等作为约束条件,建立了新的水资源优化配置模型。据此获得水资源分配问题的最优解,避免了一般多目标优化问题中存在多个最优解的不足,可有效地解决复杂水资源系统的优化配置问题。基于GIS技术将流域河网平面和断面地形数字化,据以划分计算河网和侧向支流。提出时变侧向出流过程的计算公式,以考虑引水时主干河道向支流扩散的水量,从而将圣维南方程中侧向出流项由以往的常数改进为时变流量过程。考虑数学模型出口边界水位为时变过程,使河网非恒定流数值计算更为合理。在此基础上提出了河网输水能力的数值计算方法。潮汐河口自流引水不可避免地受非恒定流影响,水流挟沙能力随之变化,而实际含沙浓度变化滞后于水流挟沙能力。为此提出时变挟沙能力的新概念,即水流挟沙能力在半潮周期内随潮流速和潮位同步变化,是时间的函数。在量纲分析基础上建立起水流挟沙能力与时变Froude数的函数关系式,再根据平衡点含沙量和相应水流参数确定关系式中的系指数,由此获得时变水流挟沙能力公式。当引水经沿海平原河网时,除入口水流受潮汐影响而具有时变的挟沙能力外,引水带来的粘性泥沙进入河网将破坏原有的泥沙输移格局,导致粘性非均匀沙在河网沉积。为此,考虑时变水流挟沙能力和粘性非均匀沙起动概率,结合河网非恒定流数值计算,建立起沿海平原河网不平衡输沙与淤积的计算方法。将该方法用于某引水工程河网含沙量的沿程变化与淤积计算,分析了河网淤积的时空分布规律,并提出相应的减淤对策,为引水工程决策提供了科学依据。更多还原

【Abstract】 Coastal plain areas always possess of large population and developed economy but lack for local water resources, which has becoming a bottleneck of economic and social development. To meet the needs of sustainable development of local economy sociaty, besides for reasonably exploiting and optimally allocating water resources in the region, transporting water from outside region is necessary to solve fundamentally the problem of lacking for water.Taking economic benefit, cost of water transport and equilibrium distribution into account synthetically, a new nonlinear objective function organically integrating three objectives is proposed. A new model for optimal allocation of water resources is developed under restricts with water supply and demand. The model can provide an optimal solution of water resources allocation, which overcomes the disadvantages of multiple optimal solutions in previous multi-objective programming, and effectively solve the problem of optimal allocation in complex water resources system.Using GIS technology to digitalize river network and section topography in the basin, the river network is divided into mainstream and lateral distributary as "reservoirs". A calculation method of time-dependent lateral outflow is proposed, which is adopted to compute water discharge from mainstream to reservoirs in water transport and proves the lateral outflow in Saint-Venant equation from previous constant to time-dependent process. Water level change at outlet boundary in the mathematical model is also considered as time-dependent process, which makes the calculation of unsteady flow in river network more reasonable. As a result a new method is proposed for calculation of water transport capacity in river network.As artesian flow from tidal estuary to river network is affected by tide inevitably, the sediment transport capacity of flow changes with it synchronously, but the actual sediment concentration lags behind it. So a new concept that the time-dependent sediment transport capacity is proposed, which means sediment transport capacity varies with tidal velocity and water level in half tide cycle and it is a function of time. Based on the dimensional analysis, the relationship between sediment transport capacity and time-dependent Froude number is constructed, and then the hydraulic parameters and concentrations in equilibrium points are chosen to determine the coefficients in the formulation, so a general formula for time-dependent sediment transport capacity is developed.When water flows through the river network in the coastal plain, besides tidal flow at the entrance with time-dependent sediment transport capacity, sediment alorg with water enters the river network and destroys the equilibrium state of sediment transport, which leads to non-uniform cohesive sediment deposition throughout the river network. Considering time-dependent sediment transport capacity and incipient probability of cohesive non-uniform sediment and integrating numerical calculation of unsteady flow, a calculation method of nonequilibrium sediment transport and deposition through the river network in coastal plain is established. The method is applied to calculate sediment concentration and deposition along the river network in a water transport project, the temporal and spatial distribution of sediment deposition is analyzed, and the countermeasures for decreasing deposition in river network are proposed, which provide scientific reasons for the decision of water transport project.更多还原