Stormwater Management Area Control

The Stormwater Management Area-flow overlay aims to protect Auckland's aquatic biodiversity. Auckland has numerous small and narrow streams. Despite their small size, these streams are home to much of our aquatic biodiversity. This biodiversity is threatened by the effects of ongoing urban development. The creation of impervious surfaces in a catchment undergoing development increases the rate and volume of stormwater runoff. This change in hydrology, unless managed, can have a significant adverse effect on streams within the catchment. Increased flows and stormwater volumes can accelerate stream erosion, particularly in steeper upper catchment areas, and can create hydrological conditions that do not support healthy aquatic ecosystems. In developed urban catchments with large areas of impervious surface, increased runoff is one of the primary causes of degraded stream health. However, in areas yet to be developed, or with existing development at low levels, development can be enabled while also protecting and enhancing in-stream biodiversity and other stream values, reducing and managing stormwater runoff, and other measures such as enhancing riparian margins. High-value, and potential value, streams at risk or particularly susceptible to the effects from development have been identified and their contributing catchment areas mapped (stormwater management area: flow (SMAF)). Future development and redevelopment in these catchments will be subject to controls to manage stormwater runoff to enable development, while at the same time protecting Auckland’s aquatic biodiversity from further decline.雨水管理区域-流量叠加区（Stormwater Management Area-flow overlay）旨在保护奥克兰的水生生物多样性。奥克兰境内分布着众多小型窄幅溪流，尽管规模不大，这些溪流却是奥克兰绝大多数水生生物多样性的栖息地。当前这些生物多样性正持续受到城市开发活动的威胁。 在处于开发进程中的汇水区内，不透水地表的增设会提升雨水径流的流速与径流量。这种水文条件的改变若未得到有效管控，将对汇水区内的溪流造成显著不利影响。径流流速与径流量的提升会加剧溪流侵蚀，尤其在坡度较陡的上游汇水区，还会形成无法支撑健康水生生态系统的水文环境。在大面积铺设不透水地表的已开发城市汇水区中，径流量增加是导致溪流生态健康退化的主要诱因之一。 不过，对于尚未开发或开发程度较低的区域，可在推进开发的同时，保护并提升溪流内的生物多样性与其他溪流生态价值，减少并管控雨水径流，还可采取修复河岸带（riparian margins）等相关措施。本数据集已识别出面临开发威胁或极易受开发活动影响的高价值与潜在价值溪流，并绘制了其汇水区范围（雨水管理区域-流量（SMAF））。上述汇水区内的未来开发与再开发活动将受到管控，通过管控雨水径流以保障开发可行，同时防止奥克兰的水生生物多样性进一步衰退。