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针对平原区城镇化背景下水系减少及连通受阻等下垫面变化引起的洪涝加剧问题,综合考虑水系结构和水力特性等因素,建立满足行洪排涝需求的平原水系连通度量方法,并以浙东沿海平原河网区为例,分析了城镇化下平原水系特征变化及其对河网连通度的影响。结果表明:1近20a来研究区水系数量和结构复杂性均存在不同程度的衰减,河网密度和水面率分别减少20%和30%左右,水系尤其是低等级河道的减少导致河网结构趋于骨干化;2河网连通度受水面率等数量特征和水系空间连接结构的共同影响,在水系数量持续减少情况下,整个河网连通度呈现先减少后增加的趋势,说明了骨干河道工程对水系空间结构特征的优化,可缓解水系减弱对河网连通的负面效应;3建立的河网连通度方法合理反映了水系数量和结构变化下的河网连通度演变规律,以及水系变化下区域排涝能力的空间差异特征,具有操作性强特点。
Aiming at the problem of increasing flood caused by the change of underlying surface such as the reduction of water system and blocked communication under the background of urbanization in the plains area, the paper establishes a method for measuring the connectivity of plain water systems that meets the demands of flood discharge and water drainage, taking into account the structural and hydraulic characteristics of the river system. Taking the coastal plain river network area as an example, the characteristics of the plain water system under urbanization and its influence on the connectivity of the river network are analyzed. The results show that: in recent 20 years, both the quantity and the structural complexity of river systems have been attenuated in varying degrees, the river network density and surface water rate have been reduced by 20% and 30% respectively, and the decrease of water system, especially the low grade river channel, (2) The connectivity of the river network is affected by the number of water surface features and the spatial connection structure of the water system. With the continuous reduction of the water system, the connectivity of the whole river network first decreases and then increases, indicating that the key channel project The optimization of the spatial structure of the water system can mitigate the negative effect of water system weakening on the river network connectivity. 3 The established river network connectivity method reasonably reflects the evolvement rules of river network connectivity under the change of water system quantity and structure, Drainage capacity of the spatial differences between the characteristics of a strong operational characteristics.