Mountains are a source of water for downstream areas; thus, it is important to understand the storage and discharge characteristics of steep mountain catchments. Nested catchment studies have indicated that the relation between catchment area and specific discharge during baseflow can represent mesoscale storage and discharge characteristics, but this is poorly understood. We found that baseflow‐specific discharge increased with catchment size in the headwater of the Arakawa River and identified the processes responsible for this spatial pattern. Synoptic discharge measurements obtained in catchment areas of 0.05 to 93.58 km² showed that specific discharge increased more than threefold with increasing drainage area. Analyses of the spatial variation in precipitation, hydrographs from three continuous gauging stations, and isotopic tracers implied that in this catchment, considerable amounts of water infiltrated in bedrock on hillslopes and did not discharge into small streams, but instead fed surface flow into a larger downstream catchment. A review of previous nested studies demonstrated three spatial patterns for specific discharge: Specific discharge may increase or decrease with catchment area, or it may be independent of area. An increase in specific discharge with area was observed only in catchments with permeable bedrock, which implies that such an increase is a useful indicator of the importance of the bedrock flow path to mountain watershed storage. The pattern of relationships between catchment area and specific discharge can be used to assess the storage and discharge properties of mesoscale catchments when the processes driving each pattern have been clarified.

中文翻译：

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汇水面积比流量的增加意味着基岩的渗透能提供较大的流量，而不是较小的山头河源流量

山区是下游地区的水源。因此，重要的是要了解陡峭的山区流域的存储和排放特性。巢式集水研究表明，基流期间集水面积与比流量之间的关系可以代表中尺度的存储和流量特性，但对此知之甚少。我们发现，荒川河上游源流的特定流量随集水面积的增加而增加，并确定了造成这种空间格局的过程。在0.05至93.58 km ^2的集水区获得的天气排放量测量值结果表明，随着排水面积的增加，比流量增加了三倍以上。分析降水的空间变化，来自三个连续测量站的水文图和同位素示踪剂表明，在该流域，大量水渗入了山坡的基岩中，没有排入小溪，而是将地表水流入较大的下游集水。对以前的嵌套研究的回顾表明，特定排放量的三种空间模式是：特定排放量可能随集水面积的增加或减少，或者可能与面积无关。仅在具有可渗透基岩的流域中观察到比流量随面积的增加，这意味着这种增加是基岩流径对山区流域存储重要性的有用指示。