scholarly journals Anti-Erosion Efficiency of Stands Installed On Degraded Land

2021 ◽  
Author(s):  
Mircea Cristian Moldovan ◽  
Tăut Ioan ◽  
Dîrja Marcel
Keyword(s):  
Surface Runoff ◽  
Land Surface ◽  
Rain Intensity ◽  
Degraded Land ◽  
Natural Factors ◽  
Significant Damage ◽  
Erosion Efficiency ◽  
Sloping Land ◽  
Two Parameters ◽  
The 19Th Century

Abstract Background: The naturally present erosion phenomenon has been active throughout the geological eras, shaping the land surface to date. Today, this phenomenon causes significant damage to the environment and human activities.In the geographical conditions of Romania, where the sloping land represents up to 67% of the national territory and supported by a complex number of natural factors, as well as the intense human interventions from the end of the 19th century and the beginning of the 20th, the vegetation and soils face serious ecological imbalances. The afforestation of degraded lands gained momentum after 1948, and the most used species were pines, especially black pine and Scots pine.Methods: In order to achieve the proposed objectives regarding the evaluation of stands in terms of anti-erosion effectiveness, were analyzed the consistency of trees, the number of trees on the surface, the weight of the seedlings, and surface runoff, from the perspective of rainfall and soil retention.Results: Analyzing the influence of rain intensity, respectively 39% in compartment 49, 38% in 73 and ground retention on surface runoff, being 28% in both compartments, it results that the two parameters directly influence surface runoff. Thus, it can be stated that indirectly surface runoff is influenced by the consistency of the stands, by the degree of proximity of the crowns, which directly influence the intensity of rain and the number of trees and the vegetation that grows under them directly influences the retention in the soil through the litter that is formed, which promotes retention.Conclusions: The results obtained suggest that indirectly surface runoff is influenced by the consistency of the tree, by the degree of proximity of the crowns, which directly influence the intensity of rain.Also, the number of trees and the vegetation that grows under them directly influences the retention in the soil through the litter that is formed, which promotes retention and by creating areas that reduce the speed of water, favoring infiltration into the soil.

Emergent constraints on the sensitivity of global land surface runoff to temperature based on CMIP6 projections

2021 ◽  
Author(s):  
Yuanfang chai ◽  
Wouter R. Berghuijs ◽  
Yao Yue ◽  
Thomas A.J. Janssen ◽  
Han Dolman
Keyword(s):  
Surface Runoff ◽  
Land Surface ◽  
Global Land ◽  
Emergent Constraints

Two parameters are required for a Budyko function to describe the land-atmosphere interaction

2021 ◽  
Author(s):  
Daeha Kim ◽  
Jong Ahn Chun
Keyword(s):  
Land Surface ◽  
River Basins ◽  
Control Surface ◽  
Primary Control ◽  
Evaporative Demand ◽  
Atmosphere Interaction ◽  
The Mean ◽  
Two Parameters ◽  
Two Parameter ◽  
Surface Changes

<p>While the Budyko framework has been a simple and convenient tool to assess runoff (Q) responses to climatic and surface changes, it has been unclear how parameters of a Budyko function represent the vertical land-atmosphere interactions. Here, we explicitly derived a two-parameter equation by correcting a boundary condition of the Budyko hypothesis. The correction enabled for the Budyko function to reflect the evaporative demand (E<sub>p</sub>) that actively responds to soil moisture deficiency. The derived two-parameter function suggests that four physical variables control surface runoff; namely, precipitation (P), potential evaporation (E<sub>p</sub>), wet-environment evaporation (E<sub>w</sub>), and the catchment properties (n). We linked the derived Budyko function to a definitive complementary evaporation principle, and assessed the relative elasticities of Q to climatic and land surface changes. Results showed that P is the primary control of runoff changes in most of river basins across the world, but its importance declined with climatological aridity. In arid river basins, the catchment properties play a major role in changing runoff, while changes in E<sub>p</sub> and E<sub>w</sub> seem to exert minor influences on Q changes. It was also found that the two-parameter Budyko function can capture unusual negative correlation between the mean annual Q and E<sub>p</sub>. This work suggests that at least two parameters are required for a Budyko function to properly describe the vertical interactions between the land and the atmosphere.</p>

scholarly journals A 368-year maximum temperature reconstruction based on tree-ring data in the northwestern Sichuan Plateau (NWSP), China

2016 ◽  
Vol 12 (7) ◽  
pp. 1485-1498 ◽  
Author(s):  
Liangjun Zhu ◽  
Yuandong Zhang ◽  
Zongshan Li ◽  
Binde Guo ◽  
Xiaochun Wang
Keyword(s):  
Tree Ring ◽  
Land Surface ◽  
Temperature Reconstruction ◽  
Temperature Variability ◽  
Ice Age ◽  
Maximum Temperature ◽  
Tree Ring Data ◽  
The Mean ◽  
Extreme Cold ◽  
The 19Th Century

Abstract. We present a reconstruction of July–August mean maximum temperature variability based on a chronology of tree-ring widths over the period AD 1646–2013 in the northern part of the northwestern Sichuan Plateau (NWSP), China. A regression model explains 37.1 % of the variance of July–August mean maximum temperature during the calibration period from 1954 to 2012. Compared with nearby temperature reconstructions and gridded land surface temperature data, our temperature reconstruction had high spatial representativeness. Seven major cold periods were identified (1708–1711, 1765–1769, 1818–1821, 1824–1828, 1832–1836, 1839–1842, and 1869–1877), and three major warm periods occurred in 1655–1668, 1719–1730, and 1858–1859 from this reconstruction. The typical Little Ice Age climate can also be well represented in our reconstruction and clearly ended with climatic amelioration at the late of the 19th century. The 17th and 19th centuries were cold with more extreme cold years, while the 18th and 20th centuries were warm with less extreme cold years. Moreover, the 20th century rapid warming was not obvious in the NWSP mean maximum temperature reconstruction, which implied that mean maximum temperature might play an important and different role in global change as unique temperature indicators. Multi-taper method (MTM) spectral analysis revealed significant periodicities of 170-, 49–114-, 25–32-, 5.7-, 4.6–4.7-, 3.0–3.1-, 2.5-, and 2.1–2.3-year quasi-cycles at a 95 % confidence level in our reconstruction. Overall, the mean maximum temperature variability in the NWSP may be associated with global land–sea atmospheric circulation (e.g., ENSO, PDO, or AMO) as well as solar and volcanic forcing.

THE INFLUENCE OF IMPROVED PLACEMENT OF FLOW-REGULATING FOREST BELTS ON THE FORMATION OF SURFACE RUNOFF OF MELTWATER

2021 ◽  
Author(s):  
A.I. Petelko ◽  
Keyword(s):  
Surface Runoff ◽  
Scientific Research ◽  
Soil Freezing ◽  
Water Runoff ◽  
Combined Design ◽  
Spring Runoff ◽  
Natural Factors ◽  
Melt Water ◽  
Forest Belts ◽  
Snow Deposition

The materials of scientific research for a number of years on the formation of melt water runoff on autumn plowing with stock-regulating forest belts of a combined design with low-growing shrubs are presented. It was revealed that the spring runoff depends on the main natural factors: moisture, soil freezing and snow deposition.

scholarly journals Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balances

2012 ◽  
Vol 16 (8) ◽  
pp. 2547-2565 ◽  
Author(s):  
G. Tang ◽  
P. J. Bartlein
Keyword(s):  
Soil Moisture ◽  
Surface Water ◽  
Surface Runoff ◽  
Land Surface ◽  
Surface Hydrology ◽  
Large Spatial Scale ◽  
Land Surface Water ◽  
Land Surface Hydrology ◽  
Water Balances ◽  
Global Vegetation

Abstract. Satellite-based data, such as vegetation type and fractional vegetation cover, are widely used in hydrologic models to prescribe the vegetation state in a study region. Dynamic global vegetation models (DGVM) simulate land surface hydrology. Incorporation of satellite-based data into a DGVM may enhance a model's ability to simulate land surface hydrology by reducing the task of model parameterization and providing distributed information on land characteristics. The objectives of this study are to (i) modify a DGVM for simulating land surface water balances; (ii) evaluate the modified model in simulating actual evapotranspiration (ET), soil moisture, and surface runoff at regional or watershed scales; and (iii) gain insight into the ability of both the original and modified model to simulate large spatial scale land surface hydrology. To achieve these objectives, we introduce the "LPJ-hydrology" (LH) model which incorporates satellite-based data into the Lund-Potsdam-Jena (LPJ) DGVM. To evaluate the model we ran LH using historical (1981–2006) climate data and satellite-based land covers at 2.5 arc-min grid cells for the conterminous US and for the entire world using coarser climate and land cover data. We evaluated the simulated ET, soil moisture, and surface runoff using a set of observed or simulated data at different spatial scales. Our results demonstrate that spatial patterns of LH-simulated annual ET and surface runoff are in accordance with previously published data for the US; LH-modeled monthly stream flow for 12 major rivers in the US was consistent with observed values respectively during the years 1981–2006 (R2 > 0.46, p < 0.01; Nash-Sutcliffe Coefficient > 0.52). The modeled mean annual discharges for 10 major rivers worldwide also agreed well (differences < 15%) with observed values for these rivers. Compared to a degree-day method for snowmelt computation, the addition of the solar radiation effect on snowmelt enabled LH to better simulate monthly stream flow in winter and early spring for rivers located at mid-to-high latitudes. In addition, LH-modeled monthly soil moisture for the state of Illinois (US) agreed well (R2 = 0.79, p < 0.01) with observed data for the years 1984–2001. Overall, this study justifies both the feasibility of incorporating satellite-based land covers into a DGVM and the reliability of LH to simulate land-surface water balances. To better estimate surface/river runoff at mid-to-high latitudes, we recommended that LPJ-DGVM considers the effects of solar radiation on snowmelt.

changing landscapes, human impact on

2019 ◽  
Author(s):  
John Bintliff
Keyword(s):  
Human Impact ◽  
Land Surface ◽  
Agricultural Technology ◽  
Short Term ◽  
Rural Landscapes ◽  
Natural Factors ◽  
Classical World ◽  
Ancient Society ◽  
Shed Light

The Classical world witnessed many forms of physical landscape change due to long-term and short-term geological and climatological processes. There have also been alterations to the land surface resulting from an interaction between human impact and these natural factors. Cyclical changes in land use, agricultural technology, economy, and politics have continually transformed the rural landscapes of the Mediterranean and the wider Classical world and their mapping, in turn, can shed light on fundamental aspects of ancient society that are not always documented in Classical texts.

Improving the representation of the prairie pothole dynamics in land surface models

2020 ◽  
Author(s):  
Mohamed I. Ahmed ◽  
Amin Elshorbagy ◽  
Alain Pietroniro
Keyword(s):  
Surface Runoff ◽  
Land Surface ◽  
Flow Simulation ◽  
Hydrologic Model ◽  
Surface Model ◽  
Prairie Pothole ◽  
Runoff Generation ◽  
Dem Resolution ◽  
Physically Based ◽  
Streamflow Simulation

&lt;p&gt;The hydrography of the prairie basins is complicated by the existence of numerous land depressions, known as prairie potholes, which can retain a substantial amount of surface runoff. Consequently, the runoff production in the prairies follows a fill, spill, and merging mechanism, which results in a dynamic contributing area that makes the streamflow simulation challenging. Existing approaches to represent the potholes&amp;#8217; dynamics, in different hydrological models, use either a lumped or a series of reservoirs that contribute flow after exceeding a certain storage threshold. These approaches are simplified and do not represent the actual dynamics of the potholes nor their spatial water extents. Consequently, these approaches may not be useful in capturing the potholes&amp;#8217; complexities and may not be able to accurately simulate the complex prairie streamflow. This study advances towards more accurate and physically-based streamflow simulation in the prairies by implanting a physically-based runoff generation algorithm (Prairie Region Inundation MApping, PRIMA model) within the MESH land surface model, and is referred to as MESH-PRIMA. PRIMA is a recently developed hydrological routing model that can simulate the lateral movement of water over prairie landscape using topographic data provided via DEMs. In MESH-PRIMA, MESH handles the vertical water balance calculations, whereas PRIMA routes the water and determines the amount of water storage and surface runoff. The streamflow simulations of MESH-PRIMA (using different DEM resolution as a topographic input) and MESH with its existing conceptual pothole dynamics algorithm are tested on a number of pothole-dominated watersheds within Saskatchewan, Canada, and compared against observed flows. MESH-PRIMA provides improved streamflow and peak flow simulation, compared to that of MESH with its conceptual pothole algorithm, based on the metrics evaluated for the simulations. MESH-PRIMA shows potential for simulating the actual pothole water extents when compared against water areas obtained from remote sensing data. The use of different DEM resolution changes the resulting pothole water extent, especially for the small potholes as they are not detected in the coarse DEM. MESH-PRIMA can be considered as a hydraulic-hydrologic model that can be used for better understanding and accurate representation of the complex prairie hydrology.&lt;/p&gt;

scholarly journals Assessment of Precipitation Error Propagation in Multi-Model Global Water Resources Reanalysis

2018 ◽  
Author(s):  
Md Abul Ehsan Bhuiyan ◽  
Efthymios I. Nikolopoulos ◽  
Emmanouil N. Anagnostou ◽  
Clement Albergel ◽  
Emanuel Dutra ◽  
...  
Keyword(s):  
Water Resources ◽  
Surface Runoff ◽  
Land Surface ◽  
Runoff Generation ◽  
Surface Exchange ◽  
Hydrologic Modelling ◽  
Study Region ◽  
Precipitation Characteristics ◽  
Model Structures ◽  
Global Water

Abstract. This study focuses on the Iberian Peninsula and investigates the propagation of precipitation uncertainty, and its interaction with hydrologic modelling, in global water resources reanalysis. Analysis is based on ensemble hydrologic simulations for a period spanning 11 years (2000–2010). To simulate the hydrological variables of surface runoff, subsurface runoff, and evapotranspiration, we used four land surface models—JULES (Joint UK Land Environment Simulator), ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems), SURFEX (Surface Externalisée), and HTESSEL (Hydrology-Tiled ECMWF Scheme for Surface Exchange over Land)—and one global hydrological model, WaterGAP3 (Water–Global Assessment and Prognosis). Simulations were carried out for five precipitation products—CMORPH, PERSIANN, 3B42 (V7), ECMWF reanalysis, and a machine learning-based blended product. As reference, we used a ground-based observation-driven precipitation dataset, named SAFRAN, available at 5 km/1  h resolution. We present relative performances of hydrologic variables for the different multi-model/multi-forcing scenarios. Overall, results reveal the complexity of the interaction between precipitation characteristics and different modelling schemes and show that uncertainties in the model simulations are attributed to both uncertainty in precipitation forcing and the model structure. Surface runoff is strongly sensitive to precipitation uncertainty and the degree of sensitivity depends significantly on the runoff generation scheme of each model examined. Evapotranspiration fluxes are comparatively less sensitive for this study region. Finally, our results suggest that there is no single model/forcing combination that can outperform all others consistently for all variables examined and thus reinforce the fact that there are significant benefits in exploring different model structures as part of the overall modelling approaches used for water resources applications.

scholarly journals It rains and then? Numerical challenges with the 1D Richards equation in kilometer-resolution land surface modelling

2021 ◽  
Author(s):  
Daniel Regenass ◽  
Linda Schlemmer ◽  
Elena Jahr ◽  
Christoph Schär
Keyword(s):  
Surface Runoff ◽  
Land Surface ◽  
Richards Equation ◽  
Wetting Front ◽  
Time Step ◽  
Infiltration Process ◽  
Numerical Convergence ◽  
Surface Modelling ◽  
Regular Grids ◽  
Land Surface Modelling

Abstract. Over the last decade kilometer-scale weather predictions and climate projections have become established. Thereby both the representation of atmospheric processes, as well as land-surface processes need adaptions to the higher-resolution. Soil moisture is a critical variable for determining the exchange of water and energy between the atmosphere and the land surface on hourly to seasonal time scales, and a poor representation of soil processes will eventually feed back on the simulation quality of the atmosphere. Especially the partitioning between infiltration and surface runoff will feed back on the hydrological cycle. Several aspects of the coupled system are affected by a shift to kilometer-scale, convection-permitting models. First of all, the precipitation-intensity distribution changes to more intense events. Second, the time-step of the numerical integration becomes smaller. The aim of this study is to investigate the numerical convergence of the one-dimensional Richards Equation with respect to the soil hydraulic model, vertical layer thickness and time-step during the infiltration process. Both regular and non-regular (unequally spaced) grids typical in land surface modelling are considered, using a conventional semi-implicit vertical discretization. For regular grids, results from a highly idealized experiment on the infiltration process show poor numerical convergence for layer thicknesses larger than approximately 5 cm and for time steps greater than 40 s, irrespective of the soil hydraulic model. The velocity of the wetting front decreases systematically with increasing time step and decreasing vertical resolution. For non-regular grids, a new discretization based on a coordinate transform is introduced. In contrast to simpler vertical discretizations, it is able to represent the solution second-order accurate. The results for non-regular grids are qualitatively similar, as a fast increase in layer thickness with depth is equivalent to a lower vertical resolution. It is argued that the sharp gradients in soil moisture around the propagating wetting front must be resolved properly in order to achieve an acceptable numerical convergence of the Richards Equation. Furthermore, it is shown that the observed poor numerical convergence translates directly into a poor convergence of infiltration-runoff partitioning for precipitation time series characteristic of weather and climate models. As a consequence, soil simulations with low resolution in space and time may produce almost twice the amount of surface runoff within 24 hours than their high-resolution counterparts. Our analysis indicates that the problem is particularly pronounced for kilometer-resolution models.

Effects of hydraulic and medium characteristics on solute transfer to surface runoff

1994 ◽  
Vol 30 (7) ◽  
pp. 145-155 ◽  
Author(s):  
J. L. Lai ◽  
S. L. Lo ◽  
C. F. Lin
Keyword(s):  
Mass Loss ◽  
Potassium Chloride ◽  
Surface Runoff ◽  
Relative Length ◽  
Packed Bed ◽  
Rate Of Change ◽  
Solute Transfer ◽  
Factors Affecting ◽  
The Media ◽  
Two Parameters

A two-stage scouring-based model including two parameters for each stage, the ultimate scoured depth and rate of change of scoured depth, was developed to describe solute transfer to surface runoff. While the first stage is a quick decrease of mass loss of solute to surface runoff, the second stage is a slow one. An experimental flume with a medium packed bed was designed. Four different sizes of glass beads were chosen to be the media and saturated with uniform concentration (20000 ppm) of potassium chloride solution before runoff occurred. In a series of experiments, runoff was passed at varied flow rate, velocities, and depths over the medium bed. Runoff samples were taken at the end of flume and the concentration of potassium chloride analysed. By use of this model, the dimensionless ultimate scoured depth and the dimensionless rate of change of each stage were investigated. The results showed that the Reynolds number within media and the relative length were two important factors affecting mass loss of chemicals.

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