Comparisons of flow time series between preimpact and postimpact periods have been widely used to determine hydrological alterations caused by reservoir operation. However, might also be characterized different climatological properties, a problem that has not well addressed. In this study, we propose framework assess the cumulative impact dams on regime over time. The impacts Three Gorges Dam (TGD) Yangtze River were investigated using framework. We reconstructed unregulated compare with...

Abstract Confluences are important locations for river mixing within drainage networks, yet few studies have examined in detail the dynamics of confluences. This study examines influence momentum flux ratio, scale flow (cross‐sectional area) and density differences between incoming flows on thermal at a small stream confluence. Results reveal that rates patterns depend event‐specific combinations three factors. The interface this confluence is generally distorted towards mouth lateral...

Abstract Although past field work at stream confluences has relied on velocity information specific cross sections to examine flow structure, detailed characterizations of spatial and temporal variations in the hydrodynamics are lacking. This study uses large‐scale particle image velocimetry (LSPIV) obtained from small unmanned aerial systems (sUAS), a method evaluated companion paper, map surficial patterns mean turbulent structures two unprecedented levels detail. LSPIV reveals...

Abstract The extent to which flows mix at confluences is pivotal for determining spatial patterns of water quality and biodiversity. Because mixing processes are complex, predicting rates characteristic scales difficult. Here we introduce a theory confluence dynamics shallow in the process controlled by switching between two modes behaviour—one similar wake behind an obstacle other layer parallel flows. Dye visualizations field-based experiments agree with theoretical predictions support...

Abstract Large‐scale particle image velocimetry (LSPIV) has emerged as a valuable tool for measuring surface velocity in variety of fluvial systems. LSPIV typically been used the field to obtain or discharge measurements relatively simple one‐dimensional flow. Detailed two‐dimensional three‐dimensional characterization flow structure relegated laboratory settings because difficulty controlling PIV limiting factors such poor seeding, need camera rectification, and challenging conditions. In...

Abstract Confluences are locations of complex hydrodynamic conditions within river systems. The effects on hydrodynamics and mixing temperature‐induced density differences between incoming flows investigated at a small‐size, concordant bed confluence. To evaluate effects, results eddy‐resolving simulations for densimetric Froude number Fr = 4.9 (weak‐density‐effects cases) 1.6 (strong‐density‐effects compared to in which the densities do not differ (no‐density‐effects cases). Flow patterns...

Abstract Measuring two‐dimensional (2‐D) patterns of flow in rivers at high resolution over large areas is challenging using traditional velocity‐measurement methods, which provide data specific locations or cross sections. Large‐scale particle image velocimetry (LSPIV) based on imagery obtained from fixed camera platforms can measure velocity the surface and generally accurate compared to near‐surface measurements by methods. The proliferation inexpensive small unmanned aerial systems...

Abstract Past work on lateral mixing downstream of river confluences has focused at individual confluences, limiting general knowledge this process. This study evaluates the average length scales, rates, and variability 43 for 150 events based contrasts in gray‐scale intensity confluent flows captured by aerial images. Only 45% exhibit complete over imaged reach. The dimensionless scale ( s d ) is 7.4 times flow width varies from = 1.1–26.3, but not all completely mix. A nonlinear spatial...

Abstract Confluences are important sites for mixing within river networks. Past work has shown that confluences is highly variable; in some cases flows mix rapidly and other remain unmixed far downstream of the confluence. The fluvial processes govern poorly understood. This study relates patterns amounts to three‐dimensional flow structure at three small confluences. It focuses on lateral fluxes streamwise momentum, which theoretical considerations suggest should influence mixing. Patterns...

Abstract Meandering river sinuosity increases until the channel erodes into itself (neck cutoff) or forms a new over floodplain (chute and is reduced. Unlike neck cutoff, which can be measured modelled without considering overbank processes, chute cutoff must at least partially controlled by channel‐forming processes on floodplain. Even though controls meandering form, that cause are not well understood. This study analyses morphology of two incipient cutoffs along East Fork White River,...

Volunteered geographic information and citizen science have advanced academic public understanding of geographical ecological processes. Videos hosted online represent a large data source that could potentially provide meaningful results for studies in physical geography—a concept we term volunteered videos (VGV). Technological advances image-capturing devices, computing, image processing resulted increasingly sophisticated methods treat imagery as raw data, such resolving high-resolution...

Abstract Meandering rivers experience fluctuations in width whenever riverbanks migrate different directions or at rates, which can be observed after individual floods. However, meandering maintain approximately constant widths over decadal timescales. This implies some timescale below fluctuates as banks independently, and above is maintained by a bank‐coupling process. coupling thought to occur either point bar deposition events induce cutbank erosion (bar‐push), (bank‐pull). coupling,...

Abstract Despite widespread recognition that confluences are characterized by complex hydrodynamic conditions, few studies have mapped in detail spatial patterns of flow at and variation these over time. Recent developments large‐scale particle image velocimetry (LSPIV) created novel opportunities to explore the temporal dynamics confluences. This study uses LSPIV map two‐dimensional structure water surface a confluence examine this Results show within is large region stagnation junction...

Global measurements of reservoir water levels are crucial for understanding Earth’s hydrological dynamics, especially in the context global industrialization and climate change. Although radar altimetry has been used to measure level some reservoirs with high accuracy, it is not yet feasible unless body sufficiently large or directly located at satellite’s nadir. This study proposes a gauging method applicable wide range using Sentinel–1 Synthetic Aperture Radar data digital elevation model...

Abstract Wind‐driven tree throw is an observable and consequential process that suddenly moves soil downslope, inverts the column, roughens surface with pit‐mound topography. Quantifying fluxes due to complicated by its stochastic nature estimation requires averaging over a large area or long time. Here, we develop theory leads dimensionless metric directly measurable from high resolution topographic data. The explains flux roughness as function of production decay rate creep‐like processes....

Abstract The spatial patterns of transport‐effective flows at confluences and the relation these to channel morphology remain poorly understood. This field study uses acoustic Doppler current profiler measurements explore structure different three small stream where flow have been obtained previously using electromagnetic meters or velocimeters for events incapable mobilizing bed material with much smaller discharges. Results show that accelerates from upstream downstream all six measured in...

Background To stem the HIV epidemic among adolescent girls and young women (AGYW), prevention programs must target services towards those most at risk for HIV. This paper investigates approaches to estimate map spatial heterogeneity of at-risk populations in three countries: Eswatini, Haiti Mozambique. Methods We analyzed biomarker factor data from recent population-based household surveys. characterized using approaches: complementary log-log regression, latent class analysis (LCA),...