Climate change will alter stream habitats through precipitation and air temperature changes and potentially threaten species that rely on contemporary streamflow and stream temperature regimes. Habitat projections are therefore critical to inform management decisions. Past and ongoing research has improved streamflow and temperature modelling in ungauged regions, but no studies merge these advancements with climate modelling for regional streamflow and stream temperatures predictions that describe stream habitat change. Here, we predict change in streamflow and stream temperature at the reach scale using projections from downscaled global climate models (GCMs) and the ‘business as usual’ carbon emission scenario. We focus on unaltered streams in six southern California watersheds using data from baseline (1982–2014) and projected end-of-century (2082–2100). Stream temperature is projected to increase regionally, with high-elevation stream reaches increasing most rapidly. There is less consistency in the streamflow projections, but a spatial and temporal homogenization of stream flow characteristics was predicted, that is, flows become more similar across the region with less inter-annual variation. Additionally, there is a regional trend towards larger high flow magnitudes and more storm events. Despite the increased frequency and magnitude of storm events, high-elevation streams are predicted to become drier for a greater portion of the year. Conversely, low-elevation streams are predicted to have longer hydroperiods. Mapping future streamflow and stream temperatures at the reach scale can direct conservation efforts to streams that remain suitable, restoration to areas that decrease in suitability for target species, and support water policies that consider future stream condition.

中文翻译：

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使用预计的气候变化来模拟未改变河流的水文和热力状况的未来变化，以支持敏感物种管理的规划

气候变化将通过降水和气温变化改变河流栖息地，并可能威胁依赖当代河流流量和河流温度状况的物种。因此，栖息地预测对于为管理决策提供信息至关重要。过去和正在进行的研究改进了未测量区域的水流和温度建模，但没有研究将这些进步与描述河流栖息地变化的区域水流和河流温度预测的气候建模相结合。在这里，我们使用来自缩小规模的全球气候模型 (GCM) 和“一切照旧”碳排放情景的预测来预测河段尺度的河流流量和河流温度的变化。我们使用基线（1982-2014）和预测的世纪末（2082-2100）的数据关注加利福尼亚南部六个流域中未改变的河流。河流温度预计将出现区域性升高，其中高海拔河流到达增加最快。水流预测的一致性较低，但预测了水流特征在空间和时间上的同质化，即整个区域的水流变得更加相似，年际变化较小。此外，存在更大的高流量和更多风暴事件的区域趋势。尽管风暴事件的频率和强度有所增加，但预计高海拔河流将在一年中的大部分时间变得更加干燥。相反，预计低海拔河流的水周期更长。