[1] Recession flows in a basin are controlled by the temporal evolution of its active drainage network (ADN). The geomorphological recession flow model (GRFM) assumes that both the rate of flow generation per unit ADN length (q) and the speed at which ADN heads move downstream (c) remain constant during a recession event. Thereby, it connects the power law exponent of –dQ/dt versus Q (discharge...

We review the trans-Andean species of Ancistrus from Panama, Colombia and Venezuela. Based on analyses of meristic, morphometric and pigmentation pattern data of preserved specimens, eight of sixteen species reported from this region are considered valid and two new species are described. Here we review Ancistrus chagresi Eigenmann & Eigenmann 1889 from both slopes of central Panama; A. centrol...

The watersheds of the Mississippi are some of the most intensively managed agricultural basins in the world. As such, they receive high loadings of nitrogen and export a large amount of nitrate to the drainage networks of the Mississippi River basin and coastal ocean. We find a positive correlation between fertilizer input and stream export of nitrogen. According to the correlation, 34% of appl...

We describe two new species of pebblesnails (Lithoglyphidae: Fluminicola) from southwest Oregon based on morphologic and mitochondrial DNA (COI, cytB) evidence. Fluminicola umpquaensissp. n., which had been traditionally identified as F. virens prior to the recent restriction of the latter to the lower Columbia River drainage, lives in lotic habitats in the Umpqua River basin. This species is r...

The Mobile Basin historically supported one of the most diverse freshwater mussel (Bivalvia: Unionidae) assemblages in North America. More than 65 species of mussels are known from the Basin, but it is difficult to determine how many species were present historically. The drainage's unique physical habitat was largely destroyed between the late 1800s and mid-1900s by impoundment and channel mod...

Agricultural chemical transport to surface water and the linkage to other hydrological compartments, principally ground water, was investigated at five watersheds in semiarid to humid climatic settings. Chemical transport was affected by storm water runoff, soil drainage, irrigation, and how streams were linked to shallow ground water systems. Irrigation practices and timing of chemical use gre...

An analysis of channel head locations provides insight into controls on drainage density, the response of landscapes to climatic change, and the delineation of source areas for channel network simulations. Channel heads and colluvial deposits were mapped in a roughly 2 km 2 area near San Francisco, California, and, although channel heads are located within colluvial deposits in hollows, many su...

Identification of high potential risk and susceptible zones for natural hazards of geological origin is one of the most important applications of advanced remote sensing technology in tropical environments. Yearly, several landslides occur during heavy monsoon rainfall in Kelantan river basin, Peninsular Malaysia, which are obviously connected to geological structures and topographical features...

We estimated the timing of paleodrainage connections in the Colorado River Basin using mitochondrial deoxyribonucleic acid (DNA) sequence divergences among populations of the speckled dace, Rhinichthys osculus. Cytochrome b and ND4L sequences were analyzed by maximum likelihood methods to estimate phylogenetic branch lengths, which were calibrated to geological time with a fossil age estimate. ...

The middle section of the lake basin of the Doce River in Minas Gerais State, Brazil is plagued by grave environmental problems, including the introduction of non-native fish, which reduces the biodiversity of this region. This study reports the presence of two newly-detected non-native species in the Doce River Basin. Sampling efforts included gill nets with mesh size of 3 to 12 mm (measured d...