scholarly journals A simple model of saturation excess runoff generation based on geomorphology, steady state soil moisture

2001 ◽  
Vol 37 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Garry Willgoose ◽  
Hemantha Perera
Keyword(s):  
Soil Moisture ◽  
Steady State ◽  
Simple Model ◽  
Runoff Generation ◽  
Saturation Excess

scholarly journals Multiple runoff processes and multiple thresholds control agricultural runoff generation

2016 ◽  
Author(s):  
Shabnam Saffarpour ◽  
Andrew W. Western ◽  
Russell Adams ◽  
Jeffrey J. McDonnell
Keyword(s):  
Soil Moisture ◽  
Overland Flow ◽  
Riparian Zone ◽  
Agricultural Runoff ◽  
Seasonal Effect ◽  
Hydrologic Response ◽  
Runoff Generation ◽  
Rainfall Events ◽  
Riparian Area ◽  
Saturation Excess

Abstract. Hydrologic connectivity associated with runoff processes is a critical concept for understanding catchment hydrologic response at the event timescale. However, to date, most attention has focused on single runoff response types in individual research catchments. Here we examine how runoff response and the catchment threshold response to rainfall affect a suite of runoff generation mechanisms in a small agricultural catchment. A 1.37 ha hillslope in the Lang Lang River catchment, Victoria, Australia was instrumented and hourly data of rainfall, runoff, shallow groundwater level and isotope water samples were collected. We analyse 60 rainfall events that produced 38 runoff events over two runoff seasons. Our results show that the catchment hydrologic response was typically controlled by the antecedent soil moisture condition and rainfall characteristics. There was a strong seasonal effect in the antecedent moisture conditions that led to marked seasonal scale changes in runoff response. Analysis of shallow well data revealed that streamflows early in the runoff season were dominated primarily by saturation excess overland flow from the riparian area. As the runoff season progressed, the catchment soil water storage increased and the hillslope connected to the riparian area. The hillslope transferred a significant amount of water to the riparian zone during and following events. Then, during a particularly wet period, this connectivity to the riparian zone, and ultimately to the stream, persisted between events for a period of one month. These findings are supported by isotope results which showed the dominance of pre-event water, and increased contributions of new water early (rising limb and peak) in the event hydrograph for wetter conditions. We conclude that event runoff at this site is a combination of subsurface event flow and saturation excess overland flow. However, during high intensity rainfall events, flashy hillslope flow was observed even though the soil moisture threshold for activation of subsurface flow was not exceeded. We hypothesize that this was due to the activation of infiltration excess overland flow and/or fast lateral flow through preferential pathways on the hillslope and saturation overland flow from the riparian zone.

Mathematical modelling of salt purification by recrystallization. Countercurrent arrangement

1986 ◽  
Vol 51 (11) ◽  
pp. 2481-2488
Author(s):  
Benitto Mayrhofer ◽  
Jana Mayrhoferová ◽  
Lubomír Neužil ◽  
Jaroslav Nývlt
Keyword(s):  
Steady State ◽  
Simple Model ◽  
Mathematical Modelling ◽  
Distribution Coefficient ◽  
Mother Liquor ◽  
Equilibrium Temperature ◽  
Operating Conditions ◽  
Limiting Case

The paper presents a simple model of recrystallization with countercurrent flows of the solution and the crystals being purified. The model assumes steady-state operating conditions, an equilibrium between the outlet streams of each stage, and the same equilibrium temperature and distribution coefficient for all stages. With these assumptions, the model provides the basis for analyzing the variation in the degree of purity as a function of the number of recrystallization stages. The analysis is facilitated by the use of a diagram constructed for the limiting case of perfect removal of the mother liquor from the crystals between the stages.

scholarly journals Effects of preferential flow on snowmelt partitioning and groundwater recharge in frozen soils

2019 ◽  
Vol 23 (12) ◽  
pp. 5017-5031 ◽  
Author(s):  
Aaron A. Mohammed ◽  
Igor Pavlovskii ◽  
Edwin E. Cey ◽  
Masaki Hayashi
Keyword(s):  
Soil Moisture ◽  
Groundwater Recharge ◽  
Preferential Flow ◽  
Frozen Soil ◽  
Time Lags ◽  
Runoff Generation ◽  
Frozen Ground ◽  
Soil Matrix ◽  
Frozen Soils ◽  
Flow Through

Abstract. Snowmelt is a major source of groundwater recharge in cold regions. Throughout many landscapes snowmelt occurs when the ground is still frozen; thus frozen soil processes play an important role in snowmelt routing, and, by extension, the timing and magnitude of recharge. This study investigated the vadose zone dynamics governing snowmelt infiltration and groundwater recharge at three grassland sites in the Canadian Prairies over the winter and spring of 2017. The region is characterized by numerous topographic depressions where the ponding of snowmelt runoff results in focused infiltration and recharge. Water balance estimates showed infiltration was the dominant sink (35 %–85 %) of snowmelt under uplands (i.e. areas outside of depressions), even when the ground was frozen, with soil moisture responses indicating flow through the frozen layer. The refreezing of infiltrated meltwater during winter melt events enhanced runoff generation in subsequent melt events. At one site, time lags of up to 3 d between snow cover depletion on uplands and ponding in depressions demonstrated the role of a shallow subsurface transmission pathway or interflow through frozen soil in routing snowmelt from uplands to depressions. At all sites, depression-focused infiltration and recharge began before complete ground thaw and a significant portion (45 %–100 %) occurred while the ground was partially frozen. Relatively rapid infiltration rates and non-sequential soil moisture and groundwater responses, observed prior to ground thaw, indicated preferential flow through frozen soils. The preferential flow dynamics are attributed to macropore networks within the grassland soils, which allow infiltrated meltwater to bypass portions of the frozen soil matrix and facilitate both the lateral transport of meltwater between topographic positions and groundwater recharge through frozen ground. Both of these flow paths may facilitate preferential mass transport to groundwater.

scholarly journals THE RICH AND THE POOR IN A SIMPLE MODEL OF GROWTH AND DISTRIBUTION

2016 ◽  
Vol 20 (7) ◽  
pp. 1934-1952 ◽  
Author(s):  
Kirill Borissov
Keyword(s):  
Economic Growth ◽  
Steady State ◽  
Simple Model ◽  
Disposable Income ◽  
State Equilibrium ◽  
Positional Concerns ◽  
The Poor ◽  
The Rich ◽  
Intertemporal Equilibrium ◽  
Unique Steady State

We consider a model of economic growth with altruistic agents who care about their consumption and the disposable income of their offspring. The agents' consumption and the offspring's disposable income are subject to positional concerns. We show that, if the measure of consumption-related positional concerns is sufficiently low and/or the measure of offspring-related positional concerns is sufficiently high, then there is a unique steady-state equilibrium, which is characterized by perfect income and wealth equality, and all intertemporal equilibira converge to it. Otherwise, in steady-state equilibria, the population splits into two classes, the rich and the poor; under this scenario, in any intertemporal equilibrium, all capital is eventually owned by the households that were the wealthiest from the outset and all other households become poor.

scholarly journals Physically-based modelling of hydrological processes in a tropical headwater catchment (West Africa) – process representation and multi-criteria validation

2006 ◽  
Vol 10 (6) ◽  
pp. 829-847 ◽  
Author(s):  
S. Giertz ◽  
B. Diekkrüger ◽  
G. Steup
Keyword(s):  
Soil Moisture ◽  
Rainy Season ◽  
Overland Flow ◽  
Soil Layer ◽  
Hydrological Processes ◽  
Runoff Generation ◽  
Field Investigations ◽  
Physically Based ◽  
In The Beginning ◽  
Headwater Catchment

Abstract. The aim of the study was to test the applicability of a physically-based model to simulate the hydrological processes in a headwater catchment in Benin. Field investigations in the catchment have shown that lateral processes such as surface runoff and interflow are most important. Therefore, the 1-D SVAT-model SIMULAT was modified to a semi-distributed hillslope version (SIMULAT-H). Based on a good database, the model was evaluated in a multi-criteria validation using discharge, discharge components and soil moisture data. For the validation of discharge, good results were achieved for dry and wet years. The main differences were observable in the beginning of the rainy season. A comparison of the discharge components determined by hydro-chemical measurements with the simulation revealed that the model simulated the ratio of groundwater fluxes and fast runoff components correctly. For the validation of the discharge components of single events, larger differences were observable, which was partly caused by uncertainties in the precipitation data. The representation of the soil moisture dynamics by the model was good for the top soil layer. For deeper soil horizons, which are characterized by higher gravel content, the differences between simulated and measured soil moisture were larger. A good agreement of simulation results and field investigations was achieved for the runoff generation processes. Interflow is the predominant process on the upper and the middle slopes, while at the bottom of the hillslope groundwater recharge and – during the rainy season – saturated overland flow are important processes.

scholarly journals Prediction of snowmelt derived streamflow in a wetland dominated prairie basin

2010 ◽  
Vol 7 (1) ◽  
pp. 1103-1141 ◽  
Author(s):  
X. Fang ◽  
J. W. Pomeroy ◽  
C. J. Westbrook ◽  
X. Guo ◽  
A. G. Minke ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Hydrological Model ◽  
Snow Accumulation ◽  
Model Parameters ◽  
Field Observations ◽  
Runoff Generation ◽  
Stream Channels ◽  
Physically Based ◽  
Set Up ◽  
Spot 5

Abstract. The eastern Canadian Prairies are dominated by cropland, pasture, woodland and wetland areas. The region is characterized by many poor and internal drainage systems and large amounts of surface water storage. Consequently, basins here have proven challenging to hydrological model predictions which assume good drainage to stream channels. The Cold Regions Hydrological Modelling platform (CRHM) is an assembly system that can be used to set up physically based, flexible, object oriented models. CRHM was used to create a prairie hydrological model for the externally drained Smith Creek Research Basin (~400 km2), east-central Saskatchewan. Physically based modules were sequentially linked in CRHM to simulate snow processes, frozen soils, variable contributing area and wetland storage and runoff generation. Five "representative basins" (RBs) were used and each was divided into seven hydrological response units (HRUs): fallow, stubble, grassland, river channel, open water, woodland, and wetland as derived from a supervised classification of SPOT 5 imagery. Two types of modelling approaches calibrated and uncalibrated, were set up for 2007/08 and 2008/09 simulation periods. For the calibrated modelling, only the surface depression capacity of upland area was calibrated in the 2007/08 simulation period by comparing simulated and observed hydrographs; while other model parameters and all parameters in the uncalibrated modelling were estimated from field observations of soils and vegetation cover, SPOT 5 imagery, and analysis of drainage network and wetland GIS datasets as well as topographic map based and LiDAR DEMs. All the parameters except for the initial soil properties and antecedent wetland storage were kept the same in the 2008/09 simulation period. The model performance in predicting snowpack, soil moisture and streamflow was evaluated and comparisons were made between the calibrated and uncalibrated modelling for both simulation periods. Calibrated and uncalibrated predictions of snow accumulation were very similar and compared fairly well with the distributed field observations for the 2007/08 period with slightly poorer results for the 2008/09 period. Soil moisture content at a point during the early spring was adequately simulated and very comparable between calibrated and uncalibrated results for both simulation periods. The calibrated modelling had somewhat better performance in simulating spring streamflow in both simulation periods, whereas the uncalibrated modelling was still able to capture the streamflow hydrographs with good accuracy. This suggests that prediction of prairie basins without calibration is possible if sufficient data on meteorology, basin landcover and physiography are available.

scholarly journals Shallow soil moisture – ground thaw interactions and controls – Part 1: Spatiotemporal patterns and correlations over a subarctic landscape

2010 ◽  
Vol 14 (7) ◽  
pp. 1375-1386 ◽  
Author(s):  
X. J. Guan ◽  
C. J. Westbrook ◽  
C. Spence
Keyword(s):  
Soil Moisture ◽  
Surface Soil ◽  
Companion Paper ◽  
Hydrological Models ◽  
Runoff Generation ◽  
Cold Regions ◽  
Shallow Soil ◽  
Thaw Depth ◽  
Study Sites ◽  
Simple Link

Abstract. Soil moisture and ground thaw state are both indicative of a hillslope's ability to transfer water. In cold regions, in particular, it is widely known that the depth of the active layer and wetness of surface soils are important for runoff generation, but the diversity of interactions between ground thaw and surface soil moisture themselves has not been studied. To fill this knowledge gap, detailed shallow soil moisture and thaw depth surveys were conducted along systematic grids at the Baker Creek Basin, Northwest Territories. Multiple hillslopes were studied to determine how the interactions differed along a spectrum of topological, typological and topographic situations across the landscape. Overall results did not show a simple link between soil moisture and ground thaw as was expected. Instead, correlation was a function of wetness. The interaction between soil moisture and ground thaw was more dependent at wetter sites. This indicates that interactive soil moisture and thaw depth behaviour on hillslopes in cold regions changes with location and cannot necessarily be lumped together in hydrological models. To explore further why these differences arise, a companion paper (Guan et al., 2010) will examine how the hydrological and energy fluxes influenced the patterns of moisture and thaw among the study sites.

Dominant drivers of runoff in a slash-and-burn affected catchment in upland Eastern Madagascar

2021 ◽  
Author(s):  
Bob W. Zwartendijk ◽  
H.J. (Ilja) van Meerveld ◽  
Ryan J. Teuling ◽  
Chandra P. Ghimire ◽  
L. Adrian Bruijnzeel
Keyword(s):  
Soil Moisture ◽  
Overland Flow ◽  
Quantitative Information ◽  
Forest Loss ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Valley Bottom ◽  
Antecedent Soil Moisture ◽  
Slash And Burn ◽  
Slash And Burn Agriculture

<p>In many tropical areas slash-and-burn agriculture is an important driver of forest loss. In areas where slash-and-burn agriculture has been practiced for decades, land cover is typically a mosaic of patches of remnant forest, fields under active cultivation, fallows in various stages of regrowth (ranging from young shrub to semi-mature), and degraded fire-climax grasslands. Although runoff generation mechanisms are expected to be different for these different patches, little quantitative information is available in this regard, particularly at the catchment scale and over longer time-scales (i.e., multiple slash-and-burn cycles).</p><p>We re-instrumented a 31 ha catchment in upland Eastern Madagascar, where slash-and-burn agriculture has been practiced for more than 70 years in 2015; it had been monitored between 1963 and 1972 as well<sup>1</sup>. We measured streamflow at two locations and overland flow and soil moisture for four hillside plots (0.05 – 1.93 ha): one plot under repeatedly coppiced and burned <em>Eucalyptus</em> and three plots under young shrub and tree fallows. One of the plots underwent rudimentary terracing in the past. We analysed the rainfall-runoff dynamics for 50 rainfall events (median 12 mm, maximum 71 mm).</p><p>For 60% of the events, the stormflow coefficient (minimum contributing area) was <3%, which is the proportion of valley-bottom wetlands and rice paddies in the catchment. Stable isotope sampling for five storm runoff events indicate a maximum total event-water contribution of 16%. However, instantaneous event-water contributions were as high as 66%. The hillside plot runoff response was dominated by saturation-excess overland flow and showed strong threshold behaviour in terms of the antecedent soil moisture storage in the upper 30 cm of the soil plus the event total rainfall amount (ASI + P). Average threshold values for overland flow occurrence ranged from 87 mm for the coppiced <em>Eucalyptus</em> to 137 mm for the young fallow plots (regardless of terrace presence). Stormflow also increased after an ASI+P-threshold was exceeded (100 mm based on the soil moisture sensors for the <em>Eucalyptus</em> plot and 150 mm for the sensors at the tree fallow plots).</p><p>These results indicate an increased hydrological connectivity between hillslopes and valley bottom under wetter conditions and that stormflow in the study catchment is strongly affected by variations in seasonal rainfall. The results will be used to validate a hydrological model to determine the net effect of concurrent changes in soil infiltrability and vegetation water use associated with forest loss and recovery on stormflow totals and the seasonal flow regime.</p><p><strong><sup>1</sup></strong>Bailly, C., de Coignac, G.B., Malvos, C., Ningre, J.M., and Sarrailh, J.M. (1974). Étude de l'influence du couvert naturel et de ses modifications á Madagascar. Expérimentations en bassins versants élémentaires. Cahiers Scientifiques, 4. Centre Scientifique Forestier Tropical, Nogent-sur-Marne, France, 114 pp.</p>

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