基于数值模拟的平原河流弯道生态治理研究

Research on Plains River Bend Ecological Management Based on the Numerical Simulation

建立基于有限体积法的平面二维水动力模型对海河流域鲁北平原典型河流弯道进行数值模拟,模拟研究不同流量和不同河床形态条件下河流弯道水流流速,并根据流速与河床冲淤关系分析不同工况下河床、河道边坡的冲淤变化,选出适宜河流弯道生态治理的河床形态,即在原始自然河床基础上进行拓宽、保持自然状态的河床形态。该河床形态的弯道流速梯度小,可以减缓两岸流速分布的不均匀性,水流动力轴线趋于河道中心线;水流流速分布趋于平缓,水面横比降小,弯顶下游低流速区域小,可以减少泥沙淤积。结合土壤生物工程技术,根据弯道水流模拟分析结果,提出平原区典型河流弯道生态治理的布设方案:弯道处河床只添加生态丁坝,或在主河槽处添加高度为15 cm及以下的潜坝。治理方案模拟结果表明添加生态丁坝可以较好地改善弯道水流流场。

Based on finite volume method of two-dimensional hydrodynamic model of Lubei Plain of Haihe River basin, typical river bend was simulated. It simulated and researched on the flow velocity of river bend under different flow rates and different river bed configurations. According to the relationship between flow velocity and river bed scour and deposition, the change of scour and deposition in the river bed and channel slope under different working conditions was analyzed and selected the river bed for^n suitable for river bend ecology management , that was the XZ bed configuration broadened on the basis of the original natural river bed and kept the natural river bed. The channel flow velocity gradient was small, it could slow the uneven distribution of the flow of the two sides and made the hydrodynamic axis tended to the center line of the river; The velocity distribution of the water flow was gentle, water surface transverse gradient reduced and the area of low velocity zone in the lower reaches of the bend was small, this could reduce sediment deposition. Combined with the soil biological engi-neering technology, in the light of the results of the simulation of the flow in the bend, it puts forward the plan of ecological management of typical river bend in plain area： adding ecological dikes in the river bend only or adding height is 15 cm or lower submerged dam in the main channel. The simulation results of the control scheme show that to add ecological dikes can improve flow distribution curve.