Impact of Urban Agglomeration on the Longitudinal Hydrochemical Profile of the Mleczna River (Central Poland)

Snowmelt or ice melt typically control diurnal streamflow cycles during rain-free periods in high-altitude alpine catchments. Evapotranspiration-controlled streamflow cycles are less prominent, but can occur simultaneously (Mutzner et al., 2015). In general, the importance of evapotranspiration for the water balance of alpine catchments is likely to increase due to changing atmospheric boundary conditions and (related) changes in land cover. In this study, we focus on controls of diurnal streamflow cycles in the Fundusbach catchment (13 km²) in the Ötztal Alps (Austria). In addition to the official gauge at the catchment outlet, we have installed three further gauges along the longitudinal river profile. Here, we are recording the variability in water level/discharge at high temporal resolution (15 min) since June 2022. We have also adapted the deterministic spatially distributed hydrological model WaSiM with hourly and high spatial resolution (25 x 25 m²) for the Fundusbach catchment. Based on this model and the observation data, we are able todetermine the diurnal streamflow dynamics and their change along the longitudinal profile, analyze the seasonal dynamics of diurnal streamflow patterns, and thus, draw conclusions about the spatially and temporally changing control variables of the diurnal streamflow cycles (data- and model-attributed) for rain-free periods outside winter. Results show that (i) the diurnal streamflow variability decreases along the longitudinal profile, (ii) the amplitude of meltwater driven runoff cycles decreases exponentially over the year, whereby (iii) evapotranspiration-driven cycles always seem to attenuate meltwater-driven cycles. At later points in the snow-free season, the signal of the evapotranspiration-induced streamflow cycles can occasionally be inferred directly from the measurement data. For these days, catchment evapotranspiration amounts can be determined from runoff data as the integral between the daily maximum (during nighttime) and minimum (during daytime). The results also indicate an altitude-dependency of the control processes along the longitudinal profile, which needs to be further investigated.Reference:Mutzner, R., Weijs, S.V., Tarolli, P., Calaf, M.C., Oldroyd, H.J., Parlange, M.B. (2015): Controls on the diurnal streamflow cycles in two subbasins of an alpine headwater catchment. Water Resour. Res., 51, 3403-3418. doi.org/10.1002/2014WR016581.

Understanding nitrous oxide production by ammonia oxidizing bacteria in an enriched nitrifying sludge

Japanese rivers where a large amount of sediment accumulates along the middle reaches are today not at grade. Nevertheless, most of their longitudinal profiles can be described by one of the mathematical functions proposed for graded rivers. For these rivers, the mathematical function should show an aspect of fluvial processes different from the explanations of grade theories. The geomorphological significance of differences in the mathematical functions describing the longitudinal profiles of rivers is discussed here. A dynamic change in the shape of longitudinal profile of a river accompanying the change in mathematical function type is proposed in relation to changes in fluvial processes and stage of evolution of a river. Most Japanese rivers can be described by either exponential or power functions. The fluvial processes of the rivers described by exponential functions are in the depositional state. The front of depositional area of gravels increases in altitude and migrates downstream. The rivers expressed by power functions are in the transportational state. The front of depositional area of gravels decreases in altitude and migrates downstream. The rivers matched by linear functions, indicating that their longitudinal profiles are almost straight lines, are in mass equilibrium: the sediment load is balanced between inflow and outflow. Through aggradational processes, the shape of longitudinal profile of a river changes with the change in mathematical function type, from exponential, to power, and finally to linear functions. The difference in the type of function best fitting the longitudinal profile of a river reflects variations in fluvial processes and the evolutionary stage of the river.

Morphotectonic control on drainage network evolution in the Perachora Peninsula, Greece

Headwater streams account for 70% or more of total stream length in most catchments, making it crucial to better understand the processes and controlling factors governing streamflow generation as well as water quality. In this context, stream water chemistry longitudinal profiles can provide valuable insights. This study examines longitudinal stream chemistry profiles across six headwater catchments in three mid-mountain ranges in Germany: The Ore Mountains (catchments OM 1 and OM 2), Black Forest (BF 1 and BF 2), and Sauerland (SL 1 and SL 2).Three to four snapshot sampling campaigns were conducted per catchment across different seasons and catchment wetness conditions. During the campaigns, water samples were collected from 22 stream monitoring points in the Ore Mountains catchments, 14 in the Black Forest, and 14 in Sauerland, and the samples were analyzed for major cations, anions, and dissolved organic carbon. Subsequently, the longitudinal profiles observed were grouped into spatial and temporal patterns.In the Ore Mountains, solute concentrations were generally stable over time. However, the spatial patterns varied between the two neighbouring catchments (OM 1 and OM 2). OM 2 exhibited chemostatic longitudinal profiles for most solutes, while OM 1 showed pronounced spatial variability in solutes such as nitrate, dissolved organic carbon (DOC), chloride, and sodium. This variability is usually linked to monitoring points located near springs, tributaries, and drainage systems. However, some spikes in ion concentrations along the stream were not linked to these obvious inflows, thus potentially indicating hotspots for groundwater inflow. The Sauerland catchments showed elevated concentrations of DOC, magnesium, calcium, and sodium in July 2023, a period associated with lower streamflow. An increase in concentration from upstream to downstream was here seen in both streams for solutes like calcium and sodium, during all snapshot campaigns. However, other solutes, like nitrate and sulfate, showed different longitudinal patterns and notable shifts in solute concentration during the snapshot campaigns in SL 2. The shifts in patterns indicate a dependency on time-variant factors like seasonal changes in water input, and land use practices. BF 1 catchment in the Black Forest showed a decreasing pattern in DOC, from upstream to downstream, while the neighbouring catchment BF 2 showed a chemostatic trend. These trends could be influenced by the land use changes within the catchments. Notable increased nitrate concentrations were seen along reaches adjacent to grassland areas and at sampling points near tile drains in OM 1, BF 1, SL 1, and SL 2.Overall, solute spatial and temporal patterns were stream-specific, with no universal behaviour observed across all catchments. This variability likely results from the interplay of factors such as geology, soils, land use, stream morphology, and climate. High-resolution spatial sampling enabled the identification of point sources and hotspots of groundwater inflow which could be missed by sparse sampling. These findings enhance our understanding of the processes regulating water quality and flow in headwater systems, providing a basis for better management of these systems.

Mass movements in mountainous areas are capable of damming rivers and can have a lasting effect on the river longitudinal profile. The long profile is commonly used to retrieve regional tectonic information, but how much dams may compromise geomorphometry-based tectonic analysis has not been systematically researched. In this study, we investigate the relationship between river dams and the longitudinal profile of the upper Indus River basin, based on interpretation and analysis of remote sensing imagery and digital elevation models (DEMs) and local field work. We identified 178 landslide, glacier and debris flow dams. Using TopoToolbox, we automatically extracted the river longitudinal profile from the 30 m SRTM DEM, determined the location of convex knickpoints and calculated the channel steepness index. One hundred and two knickpoints were detected with heights above 148 m, of which 55 were related to dams. There is good spatial correspondence between dams, convexities in the river longitudinal profile and relatively high steepness index. Different dam types have different impacts on the river profile; on the upper Indus, debris flow dams have a greater impact than landslide and glacier dams and can form knickpoints of up to 900 m. Therefore, dams may have a significant influence on the river longitudinal profile, knickpoints and steepness index, and should be considered when extracting information on regional tectonics using these indices.

Geomorphic constraints on uplift history in the Aspromonte Massif, southern Italy

Neotectonic development of drainage networks in the East Sudeten Mountains and monitoring of recent fault displacements (Czech Republic)

River channels, in general, have a concave longitudinal profile. However, some of them develop a convex longitudinal profile because discharge decreases downstream, losing transport capacity. The middle-low fluvial belt of the San Bartolomé River is developed in the eastern piedmont of the Sierra de Comechingones. This environment presents an undulating relief associated with basement blocks near the surface, covered by fluvial-aeolian sediments. This work shows the incidence of peri-mountain block distribution on the channel pattern, river cross-section and the longitudinal profile concavity along the San Bartolomé middle-low reach. The channel pattern, river cross-sections, river longitudinal profile, and peri-mountain block arrangements were analyzed by means of satellite images, aerial photographs, digital elevation models and fieldwork. Changes from a permanent hydrological regime to an ephemeral one downstream would be the cause of variability in geometric relationships and channel pattern, generating a middle reach dominated by aggradation. We found a clear correspondence between elevated morpho-structural blocks with a high sinuous incised fluvial belt and a concave longitudinal profile. On the other hand, depressed blocks are related to a low sinuous wide fluvial belt and a convex longitudinal profile, which show the influence of the peri-mountain blocks on the morphodynamics of this fluvial system.KeywordsPeri-mountain blocksMorphodynamicsSubsidenceAggradationConvexitySierra de Comechingones piedmontSierras de CórdobaArgentina

Accurate characterization of riverbed sediment is crucial for monitoring cross-sectional changes in rivers and modeling water dynamics, especially during large water discharge events. The UAV LiDAR technique, with recent advancements, offers enhanced capabilities for detailed riverbed topography mapping by eliminating surface vegetation. Despite its potential, the adoption of UAV LiDAR for riverbed cross-sectional profiling has faced delays and skepticism in regular practices. In this study, we applied the UAV LiDAR technique to measure the riverbed topography of a relatively wide river in the Ilan plain, northeast Taiwan. Our findings reveal that UAV LiDAR provides significantly more detailed results compared to Airborne LiDAR and surpasses topography measurements obtained through photogrammetry. The accuracy of UAV LiDAR-derived point clouds outperforms photogrammetry, especially when ground control points for the work of photogrammetry are insufficient or poorly distributed. Despite challenges posed by water bodies absorbing LiDAR signals, UAV LiDAR allows the production of complete riverbed topography, offering reliable estimates during dry seasons. Utilizing UAV LiDAR data, we conducted a comprehensive analysis of both cross-sectional and longitudinal riverbed profiles. The longitudinal profiles exhibit wavy frequencies associated with sediment transport processes, opening avenues for further investigation. Additionally, we evaluated Digital Elevation Models (DEMs) of Differencing (DoD) using previously acquired Airborne LiDAR point clouds. The DoD analysis unveiled the substantial magnitude of sediment movement and redistribution following an extreme rainfall event and dam failure, with a height difference exceeding 9m. This analysis, extending along the river's longitudinal profile, serves as a ground-truth field dataset illustrating how extreme rainfall events can trigger large sediment movements, posing potential hazards to the residents near rivers. Our study demonstrates the utility of UAV LiDAR in high-resolution mapping of riverbed sediment topography and provides valuable insights into sediment dynamics under extreme events, contributing to improved monitoring and hazard assessment practices.

<p>Continental collisional zone may include high-standing plateaus, both internally and externally drained. When endorheic basins are integrated into external drainage networks, the rivers could retain first order information on the capture as well as the interplay between climate and tectonic processes. The Eastern Anatolian Plateau (EAP) of the Arabia-Eurasia collision zone is one of the most representative examples of collisional plateau. It has a mean elevation of ~2000 m, presents three main endorheic basins (Van, Sevan and Urmia lakes), and is mostly drained by three river networks: the Kura-Arax drainage system to the NE, the Ҫoruh to the NW, and the Euphrates-Tigris to the SW. Seismic data indicate the presence of a thinned or totally removed lithospheric mantle beneath the plateau explaining the high heat flow and the late Cenozoic volcanic activity in the area. Despite the great number of studies on the EAP, its uplift history is still debated.</p><p>In this study we quantitatively investigated the drainage systems (river longitudinal profiles and chi-plots) and the general topographic features (swath profiles, slope, local relief, filtered topography) of the EAP. The results describe a topographic configuration characterized by a high-standing, low-relief plateau centered in the area of Lake Van, but strongly disrupted by tectonic structures with the formation of local topographic highs and lows that include endorheic basins. The fluvial network pattern is strongly disorganized and controlled by active tectonic structures. The irregular longitudinal profiles indicate that rivers are in a transient state of disequilibrium because of regional uplift, capture events or local tectonic activity. The presence of an uppermost fluvial segment characterized by low channel steepness suggests that the plateau interior has not been reached yet by the erosive wave produced by uplift. The chi-plots of the rivers draining the EAP suggest a complex uplift history, evidencing differences between the northern and the southern portions of the plateau in terms of uplift history and drainage system evolution. This uplift pattern is partially confirmed by the stratigraphic record documenting a southward younging transition from a marine to a continental depositional environment. In conclusion, the EAP is a high-standing plateau where the integration of hydrography into it is ruled by regional differential uplift and active tectonic structures.</p>

On the reintroduction of the endangered thick-shelled river mussel Unio crassus: The importance of the river's longitudinal profile

An uplift history of Crete, Greece, from inverse modeling of longitudinal river profiles

It has long been suggested that climate shapes land surface topography through interactions between rainfall, runoff and erosion in drainage basins1-4. The longitudinal profile of a river (elevation versus distance downstream) is a key morphological attribute that reflects the history of drainage basin evolution, so its form should be diagnostic of the regional expression of climate and its interaction with the land surface5-9. However, both detecting climatic signatures in longitudinal profiles and deciphering the climatic mechanisms of their development have been challenging, owing to the lack of relevant global data and to the variable effects of tectonics, lithology, land surface properties and human activities10,11. Here we present a global dataset of 333,502 river longitudinal profiles, and use it to explore differences in overall profile shape (concavity) across climate zones. We show that river profiles are systematically straighter with increasing aridity. Through simple numerical modelling, we demonstrate that these global patterns in longitudinal profile shape can be explained by hydrological controls that reflect rainfall-runoff regimes in different climate zones. The most important of these is the downstream rate of change in streamflow, independent of the area of the drainage basin. Our results illustrate that river topography expresses a signature of aridity, suggesting that climate is a first-order control on the evolution of the drainage basin.

The Colorado River in Grand Canyon has long been known as a “rapids‐and‐pools” river, with the rapids owing their existence primarily to tributary debris flows. The debris flows deposit subaerial debris fans that constrict the channel laterally and, when they enter the river, raise the bed elevation. The rapids are short‐wavelength (∼0.1 to ∼1 km), small‐amplitude (≤ ∼5 m) convexities in the river's longitudinal profile, arising from the shallow gradient in the upstream pool and the steep gradient through the rapid itself. Analysis of the entire longitudinal profile through Grand Canyon reveals two long‐wavelength (∼100 km), large‐amplitude (15–30 m) river profile convexities: the eastern canyon convexity between river mile (RM) 30 and RM 80 and the western canyon convexity between RM 150 and RM 250. Convexities of intermediate scale are also identified in the longitudinal profile. These longer‐wavelength, larger‐amplitude convexities have strong spatial correlations with high rates of debris flow occurrence, high densities of Holocene debris fans, the largest debris fans along the river, and alluvial thicknesses of 10 m or more. River profile convexities are unstable and require an active and powerful geologic process to maintain them, in this case the abundant, frequent, and voluminous Holocene debris flow activity in Grand Canyon. At all wavelengths the most likely cause for these river profile convexities is Holocene aggradation of the riverbed beneath them, driven by the coarse particles of tributary debris flows. Large enough debris flows will slow river flow for kilometers upstream, causing it to drop much of its suspended load. Integrated over time and all of the tributary point source contributions, this process will build short‐wavelength convexities into long‐wavelength convexities. For most if not all of the Holocene the Colorado River has been dissipating most of its energy in the rapids and expending the remainder in transporting fine sediment through Grand Canyon, with little or no regional incision of bedrock.