Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Impoundment density

\n\nIt should be noted that this data is now somwhat dated!\n\nNation-wide measures that would reflect the changes to flow regimes in rivers\nwere considered, for example changes in peakiness, and changes in volumes.\nHowever national long-term data sets approaching catchment scale detail were\nnot available or were of dubious quality. The regulation of river flows has\nchanged the natural flows regimes of rivers and this impacts on wetland\necosystems and aquatic biota. measure based on impoundments was considered\nto be the best available surrogate indicator for hydrological changes.\n\nThe Wild Rivers data set (Environment Australia, 1997) includes national data\non impoundments to river flow. The data set has four classes: major structures\n(dams, reservoirs); weirs; locks/sluice gates; and minor structures (banks,\nfarm dams on or immediately adjacent to stream). The Wild Rivers data set also\nincludes flow diversions data, but these are not used in the indicator here.\n\nThe maps show the location of major irrigation schemes and the major dams for\nurban water supply. The Wild Rivers impoundments data were obtained from state\npoint data sets, each of which were reclassified to a single four-class\nimpoundment rating system. Collection and derivation of data are not\nconsistent across the nation, and both point and polygon data have been\nincluded.\n\nThe polygon data has the effect of grossly inflating the number of\nimpoundments as it is possible to have 400 x 250 m grid cells within a 5 km\ngrid cell, all counted as individual impoundments. The data set is reliable at\nthe Topo250K drainage layer scale (AUSLIG, 2000).\n\nThe most modified rivers and streams are in Tasmania (Derwent, Gordon, King\nHenty, Pieman, Mersey, Forth, and Tamar Rivers). Other areas with significant\nimpacts on river flows are in the Mt Lofty Ranges around Adelaide (Fleurieu,\nMyponga, Onkaparinga, Torrens, and Gawler Rivers), the hinterland of Melbourne\n(Bunyip and Yarra Rivers) and in Queensland (Kolan, Ross, Barron and Tully\nRivers). In Western Australia the rivers with the highest impoundment values\nwere the Collie Harvey and Ord Rivers.\n\nData are available as:\n\n * continental maps at 5km (0.05 deg) cell resolution for the ILZ;\n * spatial averages over CRES defined catchments (CRES, 2000) in the ILZ;\n * spatial averages over the AWRC river basins in the ILZ.\n\nSee [further metadata](http://data.daff.gov.au/anrdl/metadata_files/pa_iccilr9ab\n__06821axx.xml) for more detail.\n\n

需要注意的是，本数据集现已略显过时！

本研究考虑了能反映河流流态变化的全国性指标，例如流量峰值变化及水量变化。然而，缺乏具有集水区尺度细节（catchment scale detail）的全国性长期数据集，或现有数据质量存疑。河流流量调节已改变河流的自然流态，这对湿地生态系统及水生生物群（aquatic biota）产生了影响。基于蓄水设施（impoundments）的指标被认为是水文变化（hydrological changes）的最佳可用替代指标（surrogate indicator）。

《Wild Rivers数据集》（澳大利亚环境部，1997）包含全国河流流量蓄水设施数据，分为四类：主要结构（大坝、水库）、堰、水闸/闸门，以及次要结构（堤岸、溪流上或紧邻溪流的农场坝）。该数据集还包含流量分流数据，但本研究未使用这些数据。

相关地图展示了主要灌溉工程及城市供水大坝的位置。Wild Rivers蓄水设施数据来源于各州点数据集，这些数据均被重新分类至统一的四类蓄水设施评级体系。全国范围内的数据收集与推导方法并不一致，且数据包含点数据与多边形数据两种类型。多边形数据会严重夸大蓄水设施数量——例如，5km网格单元内的400×250m网格单元均被计为独立蓄水设施。该数据集在Topo250K排水层尺度下具有可靠性。

受改造程度最高的河流与溪流位于塔斯马尼亚州（德文特河、戈登河、金亨蒂河、皮曼河、默西河、福斯河及塔玛河）。其他河流流态受显著影响的区域包括阿德莱德附近的洛夫蒂山脉（弗勒里厄河、迈蓬加河、昂卡帕林加河、托伦斯河及高勒河）、墨尔本腹地（本耶普河及亚拉河）以及昆士兰州（科兰河、罗斯河、巴伦河及塔利河）。在西澳大利亚州，蓄水设施密度最高的河流为科利-哈维河及奥德河。

本数据集的可用形式包括：

* 适用于ILZ区域的5km（0.05度）分辨率大陆地图；
* ILZ区域内CRES定义集水区的空间平均值；
* ILZ区域内AWRC流域的空间平均值。

更多详情请参见[进一步元数据](http://data.daff.gov.au/anrdl/metadata_files/pa_iccilr9ab__06821axx.xml)。