Rotorua Groundwater Subcatchments - Nutrient Management

The development of a set of polygons for the groundwater catchments of springs and streams relevant to NIWA's model (ROTAN; Rutherford et.al., 2009) of land use and nitrogen discharge in the Lake Rotorua catchment by GNS is summarised in the report: CR 2015/198 LR Groundwater catchment polygons within the Lake Rotorua catchment. These catchments include nine flow measurement locations that are used by NIWA to calibrate their model flows and in addition, nine polygons were generated to represent the "ungaged"catchments, i.e., areas where either groundwater flows firectly into the lake or where flows in small streams that discharge to the lake are not regularly measured. These groundwater catchment polygons were developed at a scale of 1:10,000, and uncertainties in the boundaries of these polygons were not assessed. Therefore, the use of the polygons to identify features at a scale of 1:10,000, or less, should be approached carefully.GNS开发了一套适用于NIWA罗托鲁瓦湖流域土地利用与氮排放模型（ROTAN；Rutherford等，2009）相关泉眼与溪流地下水集水区的多边形数据集，相关开发概况已总结于报告《CR 2015/198 LR 罗托鲁瓦湖流域地下水集水区多边形》中。该套集水区包含9处流量监测点位，NIWA依托这些点位对其模型流量开展校准工作；此外，还生成了9个多边形以表征“未监测集水区”，即地下水直接汇入湖泊，或是排入湖泊的小型溪流流量未被定期监测的区域。这套地下水集水区多边形以1:10000比例尺绘制，未对其边界的不确定性进行评估。因此，使用该多边形识别1:10000或更小比例尺地物时，应谨慎操作。