Recent work in the undeveloped Rio Murta Basin, located in Chilean Patagonia, identified an evolutionary trend in the fluvial system as it progresses toward and away from dynamic equilibrium. A location-for-time-substitution model employed over the longitudinal extent of a 16 km study site assessed the performance of extremal hypotheses in identifying dynamic equilibrium conditions. Numerous extremal hypotheses were successful in identifying the spatial trend, but no means were available to discern differences between them. Thus, this study uses field measurements within the evolutionary trend to propose a new metric for evaluating extremal hypotheses. A thorough review and synthesis of the extremal approach are additionally presented. The new method compares theoretical predictions against field-measured values to determine which extremal hypothesis is most effective in identifying the condition of dynamic equilibrium in a gravel-bed river. Channel width and depth are identified as the dependent stream variables that uniquely differentiate most extremal hypotheses from one another. The results indicate that extremal hypotheses based on energy metrics of the flow are most successful, with the strongest support for minimum kinetic energy and minimum specific stream power.

中文翻译：

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未开发冲积河中极值假设的评价

最近在智利巴塔哥尼亚未开发的 Rio Murta 盆地开展的工作确定了河流系统在趋向和远离动态平衡时的演化趋势。在 16 公里研究地点的纵向范围内采用的位置换时间替代模型评估了极值假设在识别动态平衡条件方面的性能。许多极值假设成功地识别了空间趋势，但没有办法辨别它们之间的差异。因此，本研究使用进化趋势内的现场测量来提出评估极值假设的新指标。另外还介绍了对极值方法的彻底审查和综合。新方法将理论预测与现场测量值进行比较，以确定哪种极值假设最有效地识别砾石床河流中的动态平衡条件。通道宽度和深度被确定为从属流变量，它们唯一地将大多数极值假设彼此区分开来。结果表明，基于流动能量度量的极值假设最成功，对最小动能和最小比流功率的支持最强。