Importance Of Tributaries Research Articles

The length and spacing of river tributaries

River networks are composed of a mainstem and tributaries. These tributaries dissect landscapes, regulate water and habitat availability, and transport sediment and nutrients. Despite the importance of tributaries, we currently lack theory and data describing whether and how tributary length and spacing varies within watersheds, thereby limiting our ability to accurately describe river network geometry. We address this knowledge gap by analyzing 4,696 tributaries across six landscapes with varying climate, tectonic setting, and lithology. Our results show that both tributary length and spacing systematically increase with downstream distance along the mainstem river, following a power-law scaling. This power-law scaling can be modulated by basin shape, with tributaries becoming shorter and, in some cases, more closely spaced as basin elongate. Furthermore, the power-law scaling may break down in cases where river networks have been disturbed by pervasive faulting, raising the possibility that the scaling we observe is not unique to all branching networks, and instead may be universal across undisturbed fluvial networks. These findings can be used to improve predictions of river network geometry and potentially to distinguish fluvial river networks from other branching networks.

A holistic approach to the spatio-temporal variability investigation of the main river water quality – The importance of tributaries

The surface water pollution can cause serious ecological disasters. An example is large-scale fish deaths due to excessive salinity, which is global problem. In order to prevent such situations, it is necessary to carry out regular monitoring of both main rivers and their tributaries. The current monitoring system is neither adapted to the variability associated with the diversified use of catchments nor to changing climatic conditions. The Bzura River is one of the most anthropogenically transformed Polish rivers. So far, no comprehensive assessment of the chemical status of its catchment has been carried out. The presented research is a continuation of the study of the spatio-temporal variability of the Bzura chemistry. It covered 19 tributaries within the boundaries of the Łódź Voivodeship. Samples were collected once a month for one hydrological year. In total, 228 samples were obtained, in which 21 parameters were measured. Spatio-temporal variability of water quality on the basis of coefficients of variation (CVs) and water quality indices (WQIs) was evaluated. Principal component analysis (PCA) and cluster analysis (CA) were also performed. In addition, the datasets were visualized using geochemical maps. Combined monitoring with geospatial analysis brings benefits in terms of efficient control and management of water resources. The tributaries were divided according to the degree of their pollution. It was found that the electrical conductivity and concentrations of dissolved oxygen, nitrates, calcium and magnesium differentiated the tributaries in terms of pollution the most. The strong salinity from agricultural and geogenic sources was found. The WQIs were higher for the tributaries than for the Bzura. It suggests that the Bzura may be polluted by the tributaries under “favorable” climatic and hydrological conditions. Therefore, smaller watercourses should be included in monitoring and become more important in terms of an effective solution to global problem of surface water pollution.

Linking movement and reproductive history of brook trout to assess habitat connectivity in a heterogeneous stream network

Summary Defining functional connectivity between habitats in spatially heterogeneous landscapes is a particular challenge for small‐bodied aquatic species. Traditional approaches (e.g. mark–recapture studies) preclude an assessment of animal movement over the life cycle (birth to reproduction), and movement of individuals may not represent the degree of gene movement for fecund species. We investigated the degree of habitat connectivity (defined as the exchange of individuals and genes between mainstem and tributary habitats) in a stream brook trout (Salvelinus fontinalis) population using mark–recapture [passive integrated transponder (PIT) tags], stationary PIT‐tag antennae and genetic pedigree data collected over 4 years (3425 marked individuals). We hypothesised that: (i) a combination of these data would reveal higher estimates of animal movement over the life cycle (within a generation), relative to more temporally confined approaches, and (ii) movement estimates of individuals within a generation would differ from between‐generation movement of genes because of spatial variation in reproductive success associated with high fecundity of this species. Over half of PIT‐tagged fish (juveniles and adults) were recaptured within 20 m during periodic sampling, indicating restricted movement. However, continuous monitoring with stationary PIT‐tag antennae revealed distinct peaks in trout movements in June and October–November, and sibship data inferred post‐emergence movements of young‐of‐year trout that were too small to be tagged physically. A combination of these methods showed that a moderate portion of individuals (28–33%) moved between mainstem and tributary habitats over their life cycle. Patterns of reproductive success varied spatially and temporally. The importance of tributaries as spawning habitat was discovered by accounting for reproductive history. When individuals born in the mainstem reproduced successfully, over 50% of their surviving offspring were inferred to have been born in tributaries. This high rate of gene movement to tributaries was cryptic, and it would have been missed by estimates based only on movement of individuals. This study highlighted the importance of characterising animal movement over the life cycle for inferring habitat connectivity accurately. Such movements of individuals can contribute to substantial gene movements in a fecund species characterised by high variation in reproductive success.

The potential role of tributaries as seed sources to an impoundment in Northern Sweden: a field experiment with seed mimics

AbstractFragmentation and flow regulation of rivers by large dams are known to obstruct the longitudinal dispersal of waterborne plant propagules between impoundments, and to affect plant community composition. However, even several decades after a dam has been built, impoundments may still have a relatively species‐rich riparian flora. We hypothesized that free‐flowing tributaries act as the major gene pools for such impoundments, thus alleviating the fragmenting effect large dams have on the main channel. The importance of tributaries as seed sources was tested by releasing wooden seed mimics in three different‐sized (0.22–6.93 m3 s−1) tributaries of an impoundment in the Ume River in Northern Sweden. In each tributary seed mimics were released, during the spring flood peak, from three points approximately 1, 2 and 3 km upstream the outlet in the impoundment. The importance of a tributary as a seed source increased with tributary size. Of the 9000 released seed mimics 1.5% reached the impoundment; 1.2% of the 9000 originated from the largest tributary and 0.3% from the middle‐sized one. The smallest tributary retained all its mimics. Copyright © 2007 John Wiley & Sons, Ltd.

Nighttime Valley Waves

Abstract This paper describes a regular oscillation observed in nighttime drainage airflow in a valley under relatively light upper-level wind conditions. The period of these oscillations is about 20 minutes with at least one harmonic at about 10 minutes. A strong coherence between tributary flow and main valley fluctuations was observed, with the phase of the tributary flow leading the valley oscillation; this indicates the importance of tributaries as major contributors to the dynamics of cold air flow in valleys.