scholarly journals Exploring Local Riverbank Sediment Controls on the Occurrence of Preferential Groundwater Discharge Points

Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 11
Author(s):  
Martin A. Briggs ◽  
Kevin E. Jackson ◽  
Fiona Liu ◽  
Eric M. Moore ◽  
Alaina Bisson ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Groundwater Discharge ◽  
Organic Matter Content ◽  
Thermal Infrared ◽  
Soil Survey ◽  
Tree Canopy ◽  
Soil Parameters ◽  
Near Surface ◽  
Physical Controls ◽  
Riparian Tree

Groundwater discharge to rivers takes many forms, including preferential groundwater discharge points (PDPs) along riverbanks that are exposed at low flows, with multi-scale impacts on aquatic habitat and water quality. The physical controls on the spatial distribution of PDPs along riverbanks are not well-defined, rendering their prediction and representation in models challenging. To investigate the local riverbank sediment controls on PDP occurrence, we tested drone-based and handheld thermal infrared to efficiently map PDP locations along two mainstem rivers. Early in the study, we found drone imaging was better suited to locating tributary and stormwater inflows, which created relatively large water surface thermal anomalies in winter, compared to PDPs that often occurred at the sub-meter scale and beneath riparian tree canopy. Therefore, we primarily used handheld thermal infrared imaging from watercraft to map PDPs and larger seepage faces along 12-km of the fifth-order Housatonic River in Massachusetts, USA and 26-km of the Farmington River in Connecticut, USA. Overall, we mapped 31 riverbank PDPs along the Housatonic reach that meanders through lower permeability soils, and 104 PDPs along the Farmington reach that cuts through sandier sediments. Riverbank soil parameters extracted at PDP locations from the Soil Survey Geographic (SSURGO) database did not differ substantially from average bank soils along either reach, although the Farmington riverbank soils were on average 5× more permeable than Housatonic riverbank soils, likely contributing to the higher observed prevalence of PDPs. Dissolved oxygen measured in discharge water at these same PDPs varied widely, but showed no relation to measured sand, clay, or organic matter content in surficial soils indicating a lack of substantial near-surface aerobic reaction. The PDP locations were investigated for the presence of secondary bank structures, and commonly co-occurred with riparian tree root masses indicating the importance of localized physical controls on the spatial distribution of riverbank PDPs.

scholarly journals Last-decade progress in understanding and modeling the land surface processes on the Tibetan Plateau

2020 ◽  
Vol 24 (12) ◽  
pp. 5745-5758
Author(s):  
Hui Lu ◽  
Donghai Zheng ◽  
Kun Yang ◽  
Fan Yang
Keyword(s):  
Heat Transfer ◽  
Tibetan Plateau ◽  
Land Surface ◽  
Organic Matter Content ◽  
Matter Content ◽  
Surface Processes ◽  
Soil Parameters ◽  
The Tibetan Plateau ◽  
Land Surface Processes ◽  
Near Surface

Abstract. Land surface models (LSMs) that simulate water and energy exchanges at the land–atmosphere interface are a key component of Earth system models. The Tibetan Plateau (TP) drives the Asian monsoon through surface heating and thus plays a key role in regulating the climate system in the Northern Hemisphere. Therefore, it is vital to understand and represent well the land surface processes on the TP. After an early review that identified key issues in the understanding and modeling of land surface processes on the TP in 2009, much progress has been made in the last decade in developing new land surface schemes and supporting datasets. This review summarizes the major advances. (i) An enthalpy-based approach was adopted to enhance the description of cryosphere processes such as glacier and snow mass balance and soil freeze–thaw transition. (ii) Parameterization of the vertical mixing process was improved in lake models to ensure reasonable heat transfer to the deep water and to the near-surface atmosphere. (iii) New schemes were proposed for modeling water flow and heat transfer in soils accounting for the effects of vertical soil heterogeneity due to the presence of high soil organic matter content and dense vegetation roots in surface soils or gravel in soil columns. (iv) Supporting datasets of meteorological forcing and soil parameters were developed by integrating multi-source datasets including ground-based observations. Perspectives on the further improvement of land surface modeling on the TP are provided, including the continuous updating of supporting datasets, parameter estimation through assimilation of satellite observations, improvement of snow and lake processes, adoption of data-driven and artificial intelligence methods, and the development of an integrated LSM for the TP.

scholarly journals EVALUATION OF SOIL QUALITY PARAMETERS IN SILVOARABLE SYSTEMS

AGROFOR ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Maria KOKKORA ◽  
Michael VRAHNAKIS ◽  
Vassiliki KLEFTOYANNI
Keyword(s):  
Soil Quality ◽  
Organic Matter Content ◽  
C Sequestration ◽  
Agroforestry Systems ◽  
Quality Parameters ◽  
Matter Content ◽  
Tree Canopy ◽  
Soil Parameters ◽  
Available Phosphorus ◽  
Research Areas

Agroforestry is considered a sustainable cultivating methodology in comparison to intensified and one-dimension agriculture, resulting in higher yields, socioeconomic benefits and environmental protection as well. The silvoarable systems constitute classification of the agroforestry systems that involve crops and trees in the same spatiotemporal scales. One of the most important benefits related to the productivity of silvoarable systems is the maintenance or improvement of soil quality. In the present study, qualitative characteristics of soils in traditional silvoarable systems in the area of Mouzaki, central Greece, were studied through the determination of basic soil parameters, including the organic matter content, total nitrogen, exchangeable potassium and available phosphorus. All systems under investigation were characterised as boundary hedgerows (livefences). The trees in the hedgerows may include mulberry, wild pear, wild walnut, and other wild tree types typical of the Mouzaki landscape, whereas the understorey crops were both arable and horticultural. Within the research areas, the effect of the trees on the concentration of the selected soil parameters was investigated. Soil samples were collected in all systems at two depths (0-30 and 30-60 cm) and at three distances from the selected trees, corresponding to half, twice, triple or quadruple the tree canopy width. The results of the research provided evidence of C sequestration in all soils under investigation, thus indicating the positive effect of agroforestry systems on the environment.

scholarly journals Last Decade Progress in Understanding and Modeling the Land Surface Processes on the Tibetan Plateau

2020 ◽  
Author(s):  
Hui Lu ◽  
Donghai Zheng ◽  
Kun Yang ◽  
Fan Yang
Keyword(s):  
Heat Transfer ◽  
Tibetan Plateau ◽  
Land Surface ◽  
Organic Matter Content ◽  
Surface Processes ◽  
Soil Parameters ◽  
Surface Model ◽  
The Tibetan Plateau ◽  
Land Surface Processes ◽  
Near Surface

Abstract. The Land Surface Model (LSM) that simulates water and energy exchanges at the land-atmosphere interface is a key component of the Earth system model. The Tibetan Plateau (TP) drives the Asian monsoon through surface heating and thus plays a key role in regulating the climate system in the Northern Hemisphere. Therefore, it's vital to understand and represent well the land surface processes on the TP. After an early review that identified key issues in the understanding and modelling of land surface processes on the TP in 2009, several progress have been made in the last decade in developing new land surface schemes and supporting datasets. This review summarizes the major advances, including (i) An enthalpy-based approach was adopted to enhance the description of cryosphere processes such as glacier/snow mass balance and soil freeze-thaw transition. (ii) Parameterization of the vertical mixing process was improved in lake models to ensure reasonable heat transfer to the deep water and to the near-surface atmosphere. (iii) New schemes were proposed for modelling water flow and heat transfer in soils accounting for the effects of vertical soil heterogeneity due to the presence of high soil organic matter content and dense vegetation roots in surface soils, or gravel in soil columns. (iv) Supporting datasets of meteorological forcing and soil parameters were developed by integrating multi-source datasets including ground-based observations. Perspectives on the further improvement of land surface modelling on the TP are provided, including the continuous updating of supporting datasets, parameter estimation through assimilation of satellite observations, improvement of snow and lake processes, and the development of an integrated LSM for the TP.

scholarly journals Exploring the Functional Strategies Adopted by Coastal Plants Along an Ecological Gradient Using Morpho-functional Traits

2021 ◽  
Author(s):  
Daniela Ciccarelli ◽  
Cleusa Bona
Keyword(s):  
C4 Photosynthesis ◽  
Abiotic Factors ◽  
Species Abundance ◽  
Organic Matter Content ◽  
Matter Content ◽  
Strong Interactions ◽  
Soil Parameters ◽  
Dry Matter Content ◽  
Ecological Gradient ◽  
Ecological Conditions

AbstractCoastal dunes are characterised by strong interactions between biotic and abiotic factors along a short gradient from the shoreline to the inland region. We carried out an ecological analysis of the vegetation in a protected area of the Italian coast to evaluate the relationships among species abundance, the occurrence of morphoanatomical traits related to leaves, stems, and roots, and soil variables. Three transects were established perpendicular to the shoreline, with 27 plots distributed in the frontal dunes, backdunes, and temporarily wet dune slacks. An analysis based on community-weighted mean values showed that the pioneer communities of the frontal dunes were dominated by ruderals that are well adapted to the harsh ecological conditions of these environments, showing succulent leaves, high limb thickness values, and low values for leaf dry matter content (LDMC). The backdune vegetation was a mosaic of annual herbaceous and perennial shrub communities showing both ruderal and stress-tolerant strategies (clonality, sclerified leaves, high LDMC values, root phenolics) consistent with less extreme ecological conditions. The dune slack areas were dominated by plants showing adaptations to both arid and flooded environments, such as C4 photosynthesis, amphistomatic leaves, and abundant aerenchyma in the roots. The invasive status, C4 photosynthesis, leaf trichomes, and aerenchyma in the roots were significantly correlated with soil humidity, organic matter content, and pH. These results demonstrate the usefulness of anatomical traits (including root system traits) in understanding the functional strategies adopted by plants. Invasive species tended to occupy plots with high levels of soil moisture, suggesting an avoidance strategy for the harsh environmental conditions of coastal sand dunes. Finally, we suggest including information regarding root systems into coastal monitoring programs because they are directly linked to soil parameters useful in coastal dune management and protection.

Physical properties and spatial distribution of the sea ice surface layer (SSL/snow) during the autumn phase of the MOSAiC expedition

2021 ◽  
Author(s):  
Ruzica Dadic ◽  
Martin Schneebeli ◽  
Henna-Reeta Hannula ◽  
Amy Macfarlane ◽  
Roberta Pirazzini
Keyword(s):  
Surface Layer ◽  
Spatial Distribution ◽  
Sea Ice ◽  
Physical Properties ◽  
Surface Scattering ◽  
Climate Feedback ◽  
Energy Fluxes ◽  
Scattering Layer ◽  
Near Surface ◽  
Ice Surface

<p>Snow cover dominates the thermal and optical properties of sea ice and the energy fluxes between the ocean and the atmosphere, yet data on the physical properties of snow and its effects on sea ice are limited. This lack of data leads to two significant problems: 1) significant biases in model representations of the sea ice cover and the processes that drive it, and 2) large uncertainties in how sea ice influences the global energy budget and the coupling of climate feedback. The  MOSAiC research initiative enabled the most extensive data collection of snow and surface scattering layer (SSL) properties over sea ice to date. During leg 5 of the MOSAiC expedition, we collected multi-scale (microscale to 100-m scale) measurements of the surface layer (snow/SSL) over first year ice (FYI) and MYI on a daily basis. The ultimate goal of our measurements is to determine the spatial distribution of physical properties of the surface layer. During leg 5 of the MOSAiC expedition, that surface layer changed from the  surface scattering layer (SSL),   characteristic for the melt season, to an early autumn snow pack. Here,  we will present data showing both a) the physical properties and the spatial distribution of the SSL during the late melt season and b) the transition of the sea ice surface from the SSL to the fresh autumn snowpack. The structural properties of this transition period are poorly documented, and this season is critical  for the initialization of sea ice and snow models. Furthermore, these data are crucial to interpret simultaneous observations of surface energy fluxes, surface optical and remote sensing data (microwave signals in particular), near-surface biochemical activity, and to understand the sea ice  processes that occur as the sea ice transitions from melting to freezing.</p>

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