ABSTRACT

This study assesses the seasonal forecast skill of river flow persistence in 46 catchments representing a range of hydrogeological conditions across Ireland. Skill is evaluated against a climatology benchmark forecast and by examining correlations between predicted and observed flow anomalies. Forecasts perform best when initialized in drier summer months, 87% of which show greater skill relative to the benchmark at a 1-month horizon. Such skill declines as forecast horizon increases due to the longer time a catchment has to “forget” initial anomalous flow conditions and/or to be impacted by “new” events. Skill is related to physical catchment descriptors such as the baseflow index (correlation ρ = 0.86) and is greatest in permeable high-storage catchments. The distinct seasonal and spatial variations in persistence skill allow us to pinpoint when and where this method can provide a useful benchmark in the future development of more complex seasonal hydrological forecasting approaches in Ireland.

摘要

这项研究评估了代表整个爱尔兰一系列水文地质条件的46个流域的河流流量持续性的季节性预报技术。根据气候基准预测并通过检查预测流量异常和观察到的流量异常之间的相关性来评估技能。在较干燥的夏季初始化时，预测的效果最佳，其中有87％的预测显示相对于在1个月内的基准具有更高的技能。随着集水区不得不“忘记”初始异常流量条件和/或受“新”事件影响的时间更长，随着预报范围的增加，这种技能也会下降。技能与物理流域描述符有关，例如基流指数（相关系数ρ = 0.86），并且在可渗透的高储存流域中最大。持久性技能的明显季节性和空间差异使我们能够确定何时何地该方法可以为爱尔兰将来开发更复杂的季节性水文预报方法提供有用的基准。