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Bathymetric LiDAR technology is a technology used for simultaneous data acquisition regarding the morphology of the bottom of water reservoirs and the surrounding coastal zone, realized from the air, e.g., by plane or drone. Contrary to the air topographic LiDAR, which uses an infrared wavelength of 1064 nm, bathymetric LiDAR systems additionally use a green wavelength of 532 nm. The green laser can penetrate the water, which makes it possible to measure the depth of shallow water reservoirs, rivers, and coastal sea waters within three Secchi depths. This article presents the theoretical basis for the construction of a green laser. Against the background of other methods of measuring the bottom of water reservoirs, the technology using waves from the visible light range is presented in detail in the assessment of the bottom morphology of shallow water reservoirs. The possibilities of using green laser in lidar bathymetry implemented in particular in non-navigable regions are shown. The results of the researchers’ work on river processes (erosion, sedimentation), design of stream restoration, determination of morphometric parameters of the riverbed, as well as assessment of the topography of the marine coastal bottom zones are summarized. The development direction of lidar bathymetry is discussed.

Strike‐slip faults act as landscape change agents, offsetting rivers, driving river capture, and generating hillslope responses. In this study, inspired by the hyperarid Atacama Fault System in Chile, we use numerical models to investigate how landscapes that experience oscillatory dry and humid periods respond to strike‐slip faulting at variable slip rates. Our results show that riverbed aggradation from hillslope sediment flux during dry periods delays stream capture, increases deflection angles of fault‐crossing channels, and produces highly perturbed longitudinal river profiles. In some cases, these phenomena, as well as the thickness of aggraded sediment, are slip‐rate dependent. Lags in capture timing and/or fully missed captures that occur in landscapes with climatic oscillation have a profound impact on the long‐term evolution of strike‐slip landscapes. Our work also highlights the importance of hillslope contributions to landscape modification in arid and semi‐arid settings with ephemeral rivers.

Interactions of fluvial and eolian processes are prominent in dryland environments and can significantly change Earth surface morphology. Here, we report on sediment records of eolian and fluvial interactions since the last glacial period, in the semiarid area of northwest China, at the limit of the Southeast Asian monsoon. Sediment sequences of last glacial and Holocene terraces of the Yellow River are composed of channel gravels, overlain by flood sands, eolian dunes, and flood loams. These sequences, dated by optically stimulated luminescence, record interlinks between fluvial and eolian processes and their response to climate change. Sedimentologic structures and grain-size analysis show flood loams, consisting of windblown sediment, deposited from floodwater suspended sediment. The gravel and sand were deposited during cold periods. During transitions from cold to warm phases, the river incised, and dunes were formed by deflation of channel and floodplain deposits (>70 and 21–16 ka). Dunes also formed at ~0.8 ka, probably after human intervention. After dune formation, flood loam covered dunes without erosion during peak discharges at the beginning of the subsequent warm period. The fluctuations of the Southeast Asian monsoon as a moisture-transporting agent have perhaps been the driving force for interactions between fluvial and eolian processes in this semiarid environment.

Flume experiments were conducted to comprehend the impact of different patterns of an emergent vegetation patch on the flow field and the scour process in natural rivers. Velocity measurements, flow visualization, and scour tests were undertaken around different vegetation patch patterns, which were simulated inspired by the expansion process of a typical instream vegetation. The patch expansion process was idealized with an initially circular patch of rigid emergent stems becoming elongated due to positive and negative feedbacks. The expansion of the vegetation patch was considered to occur in three stages, in which the density of the patch from the previous stage was increased while the patch was also elongated by connecting at its downstream side with another sparser vegetation patch. These stages were replicated succesively by increasing the density and elongating the patch. In this way, two processes (i.e., elongation and decrease in permeability), which usually have hydrodynamically opposite effects on flow fields, were simulated at the same obstruction. Despite generally elongated obstacles being streamlined bodies, the morphometric analysis obtained by laser scanner revealed that streamlined elongation of permeable patches amplifies global scour and enhances localization of the local scour hole. This situation implies that as the patch expands, in the wake region, the steady‐wake region becomes shorter, turbulence diminishes, lateral shear stress enhances, and deposition cannot occur far from the patch. Consequently, as the patch expands, the hydrodynamic consequences may restrict further patch expansion after a certain length/density. Plain Language Summary What effect does enlarging a single patch have on the local flow field and scour pattern? This research question was examined experimentally. Despite the fact that streamlined patches are hydrodynamically favorable formations, morphometric scour measurements show that the streamlined extension of permeable patches increases global scour and promotes local scour hole localization. As the patch develops, the steady‐wake zone of low velocity and suppressed turbulence that favors sediment entrapment decreases restricting its expansion. Key Points Experiments were conducted to see the impact of different patterns of an emergent vegetation patch on flow field and scour in rivers Streamlined bodies are hydrodynamically favorable bodies. Yet, tests showed that the elongation of patches increases scour and localization The steady‐wake zone becomes shorter as the patch elongated, hence restricting the patch's expansion

Fan‐shaped sedimentary deposits are key indicators of paleoclimate on Mars. The largest example, a multi‐lobed deposit (>1,000 km2) at the outlet of Hypanis Valles, may have formed either subaerially or at the edge of a water body. We used a numerical model to test whether these contrasting basin boundary conditions would cause deposit geometries that are diagnostic and distinguishable from orbit. We compared depositional scenarios with either (a) fully subaerial conditions, (b) a constant water level, or (c) a falling water level. In the model, standing water generates deposits that are thicker, less extensive, and increase in dip angle from proximal to distal locations. Nonetheless, deposit geometries for all scenarios are consistent with orbital observations, which are inconclusive regarding a topset‐foreset break that would indicate standing water. Thus, it is possible that the Hypanis deposits formed subaerially, without a water body onlapping the Mars dichotomy boundary. Plain Language Summary On the surface of Mars, outcrops of sedimentary rock hold clues to climate conditions in the early history of the planet several billion years ago. Based on satellite observations, a particularly large, fan‐shaped feature has been interpreted as either a sediment fan deposited entirely on land, or instead as a river delta formed at the edge of an ancient lake or ocean. Distinguishing between these scenarios, which imply vastly different amounts of water, is critical to determining ancient surface conditions. We used a computer model to simulate the formation of the sediment deposits under different scenarios and compared the modeled deposits to satellite observations. Results suggest that while previous work has interpreted the Hypanis deposits as remants of a delta marking the edge of an ancient ocean, the deposits could have formed entirely on land and therefore did not require an ancient ocean. Key Points The Hypanis sediment fan is the largest on Mars and has been previously interpreted as a delta formed near the dichotomy boundary We reformulated a numerical model to test if scenarios with and without standing water in the basin cause distinctive deposit geometries Comparison to orbital data suggests that the Hypanis deposits could have formed subaerially and did not require an ancient ocean

The Pleistocene development of the Vasilikos River exemplifies the interaction of focused, tectonically induced surface uplift and climate-influenced changes. The resulting sediments are well exposed in Vasilikos Quarry and in the main river catchment further east. An important erosional surface incises the highest-level (oldest) fluvial conglomerates, down into Late Pliocene – Early Pleistocene open-marine mudrocks (Nicosia Formation), allowing integration with the circum-Cyprus sedimentary–geomorphic development (F1–F4 stages). To determine where the quarry deposits lie in relation to the Vasilikos river catchment, the fluvial deposits were mapped and valley profiles were constructed, revealing four main episodes, each associated with incision and distinctive fluvial deposition. Source lithology strongly influenced channel morphology, infill and adjacent slope-sediment (colluvium) composition. Palaeosols, particularly red-brown terra rossa, developed on abandoned fluvial terraces and adjacent hillslopes, especially overlying F3 surfaces. The combined evidence allows close correlation of the Vasilikos river and quarry deposits. Relatively coarse (chalky conglomerate/breccia) and fine-grained colluvium (calcareous silt – Cyprus harvara) developed especially on lower hillslopes following incision (mainly above F2 and F3 surfaces). Based on regional comparisons, overall sediment aggregation ended during the Early Pleistocene. The F1–F2 surfaces and deposits are inferred to be Middle Pleistocene, the F3 ones later Middle Pleistocene and the F4 ones near the Middle–Late Pleistocene boundary. Geomorphology and deposition were tectonically forced during strong, focused Early–Middle Pleistocene surface uplift. Coarse clastic ruff-off and palaeosol development (terra rossa) and related sediment aggradation are inferred to have increased during warm, humid periods. Late Pleistocene geomorphology and deposition were more influenced by climatic change, with semi-perennial streamflow, rapid sediment aggradation and palaeosol (terra rossa) development during warm, humid periods (interglacials). Cooler (glacial) periods enhanced fluvial-incision, sediment-bypassing and hillslope colluvial processes (e.g. frost shattering, downslope creep and mass flow) when sediment transport (bypassing) exceeded sediment supply. Neotectonic faulting affected the catchment but did not greatly affect geomorphology or sediment supply. Although climate / climate change (and eustatic sea-level change) had an important influence, tectonics is interpreted as the fundamental driver of geomorphological development and fluvial sedimentation, with implications for other areas, regionally to globally.

The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily) intensive survey during a flood (a period of nine days) with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends.

Global demand for vegetable oil and high oil palm yield have driven the rapid expansion of oil palm plantations in tropical countries. The research literature widely recognizes the effects of forest cover conversion into oil palm on biodiversity, deforestation, and carbon dynamics. However, research on the ecohydrological impacts of oil palm plantations is sparse, despite studies indicating that oil palm development may reshape land-water interactions and the availability and movement of water at different spatial and temporal scales. We address this gap by conducting a systematic literature review on oil palm development and its relation to ecohydrological processes. We found 139 relevant papers up to the year 2021, addressing different ecohydrological processes related to oil palm. We reviewed their spatiotemporal scales, geographic distribution, oil palm species and age, and the effects of land conversion from forest, cropland, and pastures. We also incorporated societal aspects regarding community perceptions of water. Our review highlights the effects of oil palm plantations on three main components of the water cycle: (i) land-atmosphere, (ii) fluvial systems, and (iii) soils and groundwater. Most studies include analyses of the Indo-Malayan and Australasian biogeographical regions (113), followed by the Neotropics (49) and the Afrotropics (15). Compared to rainforests, oil palm monocultures are warmer and drier. They have higher evapotranspiration (ET) rates, lower runoff regulation and infiltration capacity, and lower soil organic carbon (SOC). Although less often implemented, alternative oil palm management practices, including oil palm agroforestry, can help to mitigate some of these effects. Forest to oil palm conversion is the most studied land transition, while conversions from croplands, pastures, and grasslands are less studied. Overall, we identify gaps in understanding the long-term effects of management on ecohydrological processes under different land conversions, especially in the Neotropics and the Afrotropics, precluding research-informed policy to manage impacts of this expanding crop.

The Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon. Plain Language Summary The Perseverance rover collected seven oriented samples of bedrock at the front of the apron‐like sediment deposit in the western side of Jezero crater, Mars. Grains and cements in these sedimentary rocks were likely deposited by water or formed in the presence of water in a range of past environments that predate the first signs of life on Earth. This study describes the geologic context and chemical composition of these samples and discusses how, upon return to Earth, they can be used to search for potential signs of past life, understand when and for how long Mars was habitable and why its climate changed. Studies of the returned samples would seek to detect and analyze organic compounds that may be present below the detection limit of the rover instruments, particularly in the finest‐grained rocks, and look for the traces of prebiotic processes or past life in all collected samples of sedimentary rocks. Additional analyses can also constrain tell us when, why and for how long the rivers and lakes existed in Jezero crater. The presence of diverse materials in rocks that were deposited by or into water can transform current views of Mars science and habitability outside of Earth. Key Points The Perseverance rover has collected seven cores of aqueously deposited sandstones and siltstones at the front of Jezero's western fan Hydrated sulfate, clay and carbonate minerals in the cores record the history of Mars's volatiles and surface habitability The same minerals may preserve organic and inorganic signals of abiotic, prebiotic and biological processes

The Shiyang River is an important ecological pillar in northwest China, sustaining Minqin oasis and its surrounding society. However, the basin has long been plagued by water scarcity and ecological fragility. Although the river classification is critical for understanding the complexity, diversity, and ecological functions of rivers, and the foundation of river management and watershed ecological restoration, it has not received adequate attention in this region. To obtain a deeper and comprehensive understanding of the Shiyang River, this study utilizes the Rosgen stream classification system to assess the river morphology, geomorphic features, and hydrologic processes. The results showed that seven first-level and fourteen second-level river types can be identified along 53 river sections of the Shiyang River. Further comparison analysis on the hydrologic parameters for each river type demonstrated a strong positive correlation between discharge and all river parameters. As discharge increased, channels with moderate to high width/depth ratios experienced significant lateral adjustments. A consistent channel gradient, coupled with higher discharge, facilitated the transition from single to multiple channels. Braiding tendencies were more pronounced in rivers where riverbeds were wider and shallower with higher stream power. Additionally, water-flow shear stress decreased with the increase in the width/depth ratio. This study offered critical insights into the Shiyang River’s forms and processes and for the river management and ecological restoration practices.