你正在寻找的概念有两个类别的排水流域,endhoreic盆地和cryptorheic盆地。Endhoreic盆地不排水的排水流域到海洋,地面上或下面。endhoreic盆地的河流流向当地较低的位置。在一些地方,这些低斑点是永久被水覆盖。例子包括里海,死海,大盐湖。我怀疑你不会计算这些河流的水体的流动是永久性的。但是在其他endhoreic盆地的尸体只是偶尔水湿。这些干湖床成为短暂的湖泊在罕见情况下异常高的降水。Amargosa河,例如,偶尔体验高流率,通常干燥Badwater盆地在加州死亡谷成湖。这个湖不会持续很长时间。 Another example is Lake Eyre in South Australia. Lake Eyre is dry most of the time, but occasionally it does get visibly wet, and very rarely it gets quite wet and then takes a couple of years to dry. There are several rivers in the Lake Eyre Basin that occasionally feed the lake. One of them is the Fincke River, one of oldest rivers in the world. The Fincke River is typically dry. On the rare occasion when water runs through it, the flowing water usually sink into the ground before going very far. But every once in a while, sufficient rainfall falls to enable the Fincke to flow all the way to Lake Eyre. Yet another example is Okavango River, as mentioned by Jean-Marie Prival. In the aftermath of the wet season, the Okavango Delta drains into the Thamalakane River, which in turn drains into the Boteti River, which in turn drains into the Ntwetwe Pan. The Ntwetwe Pan is typically a very dry and nearly lifeless salt pan. The Boteti usually dries up before it reaches the Ntwetwe Pan. There are many other examples of endhoreic basins in the world where the lowest spot is a salt pan that is only occasionally covered with water. ----- The other category I mentioned are cryptorheic basins. These are typically associated with karst. Karst topography oftentimes results where the surface rock is made of easily dissolved limestone. Much of the drainage in cryptorheic basins is hidden because it occurs underground, hence the *crypto* prefix. The upper Danube provides a nice example. It eventually runs dry almost half of the year because its waters sink into the Danube Sinkhole. This sinking happens all year round, but at times the above ground flow remains sufficient to keep the upper Danube flowing. The underground flow eventually merges to form the Radolfzeller Aach, which is a tributary of the Rhine. The underground flow drains to the North Sea while the above ground flow drains to the Black Sea. There are many other losing streams (streams that lose rather than gain water) in the world. Another example is the Lost River in West Virginia. It disappears under Sandy Ridge and reemerges a couple of miles (three kilometers) away on the other side of the mountain as the headwaters of the Cacapon River. There are several other streams named Lost River in the US. Eastern Australia also has many disappearing rivers. The Great Artesian Basin is a large cryptorheic basin that ultimately empties to the ocean. Some of the rivers in eastern Australia disappear, not because of evaporation, but because their waters sink to replenish the Great Artesian Basin.