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Sediment supplies are a fundamental component of alluvial river systems, but the importance of sustained supplies of externally derived sediments for the evolution of meandering planforms remains unclear. Here we demonstrate the importance of sediment supply in enhancing the growth of point bars that influence the rate of sinuosity increase through flow deflections in meander bends. We use an archive of Landsat images of 16 meandering reaches from across the Amazon Basin to show that rivers transporting larger sediment loads increase their sinuosity more rapidly than those carrying smaller loads. Sediment-rich rivers are dominated by downstream-rotating meanders that increase their sinuosity more rapidly than both extensional and upstream-rotating meanders. Downstream-rotating meanders appear to establish larger point bars that expand throughout the meander, in contrast to extensional meanders, which have smaller bars, and upstream rotating meanders, which are characterized by deposition over the bar head. These observations demonstrate that the size and position of point bars within meander bends influences flow routing and thus controls the dominant direction of meander growth. Rivers with low sediment supplies build smaller point bars, which reduces their capacity to increase meander curvature and the resulting sinuosity.

The existence of ancient fluvial systems on Mars is widely accepted, but little is known about how quickly they formed, or what environmental conditions controlled their evolution. We analyzed a sequence of well-preserved inner-bank bar deposits within the meander bends of a multistacked sinuous fluvial ridge in Aeolis Dorsa and compared them to similar features on Earth to establish the conditions required for their formation. Our results reveal that these Martian channels were highly aggradational, rising an order of magnitude higher than terrestrial rivers. This evolution occurred over very rapid time scales, with our estimates suggesting that some entire inner-bar set deposits, and therefore the aggradational channel, may have formed in less than a single Martian year, with upper bounds of a few decades. We suggest that this unique channel topography was created by a rapidly rising downstream water body, triggered by a sequence of externally sourced megafloods (e.g., crater lake breaches).

<p>Detailed methodological approaches and rationale for calculations and deposit interpretations for channel AD1 (Aeolis Dorsa, Mars).  </p>

&lt;p&gt;Mangroves provide critical ecosystem services that support livelihoods and communities at the coastal margin. They are key natural flood defences to tropical cyclone driven storm surges, they store sediment that is vital for maintaining delta surface elevations in the face of rising sea levels, and transfer key nutrients to agricultural land. Over the past few decades, stressors on mangroves have increased with associated declines in global areal extent, and growing concern about their condition, including for forests that have been restored or afforested. Most remaining mangrove forests comprises a mix of ages and quality. Limited research exists exploring how differing age, structure and health of mangroves impacts sediment retention and aids the dissipation of wave and storm energy, and links these physical processes to the delivery of ecosystem services.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In this study, we demonstrate how mangrove age and health differentially impacts rates of sedimentation, attenuates water level and tidal propagation and aids storm energy dissipation along a section of mangrove forest in Thai Binh province on the Red River Delta in Vietnam. Data were collected over a four month period and highlight spatially variable responses to tides and the increasing influence of the nearby Thai Binh River. We show that sedimentation rates vary from 0.8 m/yr to 0.14 m/yr with increasing distance inland, whilst peak tidal range varies from 1.5 m to 0.5 m with mangrove age. &amp;#160;We demonstrate that these spatial patterns correlate not only to distance inland, but also mangrove age, and the provision of ecosystem services as recorded by household surveys from local communities. This highlights the need for global mangrove databases to account for mangrove quality and health data in order to capture definitively the ecological, hydrodynamic and sedimentological impacts of mangrove forests on coastal and deltaic regions.&lt;/p&gt;

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&lt;p&gt;Flooding affects &gt;300 million people each year and causes loss of life, damage to infrastructure, and long-term mental and physical health problems. Across many parts of the globe, climate change is projected to increase the magnitude, frequency, and intensity of rainfall events, thus exacerbating future flood risk and increasing the demand for flood alleviation schemes. Agricultural land covers 39% of Europe, and as such intercepts a significant fraction of precipitation. Agricultural intensification has increased soil compaction and decreased soil porosity and permeability, thus decreasing infiltration, storage and groundwater recharge. Here, we report on experiments that aim to constrain the effects of using cover crops to increase soil porosity and permeability and hence decrease runoff during rainfall events in three arable fields in East Yorkshire, UK.&lt;/p&gt;&lt;p&gt;Half of each field was treated with a cover crop between harvest and winter cultivation, and the organic matter of this crop was incorporated into the soil. The second half of each field was used as a control. A suite of methodologies is being used to assess the long-term influence of this extra organic matter content on soil structure, health and permeability:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;An array of soil moisture loggers (Delta-T PR2/4, DalesLandNet MKII, GroPoint Profile 2625-N-T-4) was deployed in each field to provide long term soil moisture data at high temporal resolution;&lt;/li&gt; &lt;li&gt;Roaming soil moisture measurements (Campbell Scientific HydroSense II) were used to increase spatial coverage and resolution;&lt;/li&gt; &lt;li&gt;Laboratory measurements of soil density, ambient soil moisture content, porosity, permeability, and nutrient content (nitrogen, phosphorous and potassium); and&lt;/li&gt; &lt;li&gt;A 3D MODFLOW model parameterised with collected data was used to assess the long term impact of increased soil porosity and permeability on rainfall transmission in to surface water drainage systems.&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;Preliminary results suggest that enhanced organic matter &amp;#8211; delivered through cover crops &amp;#8211; increases soil nutrient and moisture retention and decreases the peak flow stage in adjacent drainage channels after intense rainfall events. These observations suggest soil restoration may provide an important mechanism for attenuating flood peaks under future climate scenarios.&lt;/p&gt;