Comprehensive Atlas of Beach Shoreline Features Within Protected Natural Landscapes of Japan

A river is a substantial natural watercourse that flows through a defined channel toward another river, lake, wetland, sea, or inland basin. Its system may include tributaries, distributaries, floodplains, seasonal reaches, gorges, waterfalls, and deltas far beyond any single mapped park relationship. The distinction from a stream depends on local convention, scale, and source usage rather than one universal rule.

A waterfall is a named point or reach where a river or stream descends abruptly over a vertical face, steep rock step, or sequence of drops. Its form may reflect resistant rock layers, faulting, glacial hanging valleys, lava flows, river incision, or changing channel geometry. The category includes single drops and cascades recognized as one feature but does not imply perennial flow or a particular height.

A lake is an inland body of standing water occupying a natural or substantially natural basin and supplied by precipitation, groundwater, streams, rivers, meltwater, or combinations of these sources. Lakes can form through tectonic, volcanic, glacial, karst, fluvial, coastal, or impact processes and may drain externally or remain closed. Size alone does not consistently separate lakes from ponds, so the established entity name should be respected.

A pond is a relatively small body of standing water occupying a natural or modified depression. It may be permanent, seasonal, spring-fed, rain-fed, stream-connected, glacial, karstic, or biologically influenced, but none of those properties follows from the label alone. The boundary between pond and lake varies across local naming systems and cannot be reduced to one universal size or depth threshold.

A stream is a natural flowing watercourse contained within a channel, generally smaller than a river but defined primarily by local naming and hydrological context. Streams may be perennial, seasonal, intermittent, spring-fed, glacial, or ephemeral and often form tributaries within larger drainage networks. No universal width or discharge threshold cleanly separates a stream from a river.