More recently, debris-avalanche and pyroclastic-flow deposits from the 1980 eruption of Mount St. Helens (Washington, USA) blocked tributary drainages of the North Fork Toutle River and enlarged several preexisting lakes.
Flooding of the Ob proper and of the Irtysh obstructs the minor tributaries' drainage.
A breakthrough in understanding urban sources of PAHs came in 2003, when staff with the City of Austin, TX, noted elevated PAH concentrations (ΣPAH16 > 1000 mg/kg) in some sediment samples collected from small tributaries and drainages in largely residential areas.
Investigators found that the potential existed for feces to enter the tributary from a drainage canal in the camp and from the open septic disposal pit that was used to handle the waste.
The disease occurs in rural villages, typically in alluvial valleys that contain a main drainage tributary of the Danube River.
For instance, the authors collected many individuals of P. hypselopterus at Bear Creek (tributary to St . Johns Baydrainage), which has its headwaters less than two air miles from the headwaters of Juniper Creek, a tributary of the Chipola-Apalachicola Rivers.
Ensuing headcut erosion of countless tributaries has induced drainage network extension, draining large areas of the swamp and lowering the groundwater levels.
Four tributaries of varying drainage areas and three main-stem sites were monitored, and nutrient grab samples were collected weekly from 2006 to 2016 and analyzed for dissolved reactive phosphorus (DRP), nitrate-nitrogen (NO3-N), total nitrogen (TN), and total phosphorus (TP).
Hierarchical analyses of geographic structuring within each ecotype based on all samples indicated that sea/river-type sockeye populations spawning in different tributaries within a drainage were genetically less differentiated than lake-type populations rearing in different lakes within a drainage, regardless of region (FSC values in Table 2).
The major tributary in the uppermost drainage basin, the Yalongjiang, also flows mainly through the Songpan Garze terrane.
