scholarly journals Modelling Recharge from Irrigation Developments with a Perched Water Table and Deep Unsaturated Zone

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 944 ◽  
Author(s):  
Glen R. Walker ◽  
Dougal Currie ◽  
Tony Smith
Keyword(s):  
Vadose Zone ◽  
Numerical Models ◽  
Environmental Risks ◽  
Time Lags ◽  
New Developments ◽  
Perched Water ◽  
Perched Water Table ◽  
Water Tables ◽  
Temporal And Spatial ◽  
Parameter Ranges

Modelling of recharge under irrigation zones for input to groundwater modelling is important for assessment and management of environmental risks. Deep vadose zones, when coupled with perched water tables, affect the timing and magnitude of recharge. Despite the temporal and spatial complexities of irrigation areas; recharge in response to new developments can be modelled semi-analytically, with most outputs comparing well with numerical models. For parameter ranges relevant to the western Murray Basin in southern Australia, perching can reduce the magnitude of recharge relative to irrigation accessions and will cause significant time lags for changes to move through vadose zone. Recharge in the vicinity of existing developments was found to be similar to that far from existing developments. This allows superposition to be implemented spatially for new developments, thus simplifying estimation of recharge. Simplification is further aided by the use of exponential approximants for recharge responses from individual developments.

scholarly journals Modelling Groundwater Returns to Streams From Irrigation Areas with Perched Water Tables

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 956 ◽  
Author(s):  
Dougal Currie ◽  
Tariq Laattoe ◽  
Glen Walker ◽  
Juliette Woods ◽  
Tony Smith ◽  
...  
Keyword(s):  
Surface Water ◽  
Vadose Zone ◽  
Transfer Functions ◽  
Root Zone ◽  
Integrated Modelling ◽  
Perched Water ◽  
Modelling Method ◽  
Murray River ◽  
Water Tables

Quantifying the magnitude and timing of groundwater returns to streams from irrigation is important for the management of natural resources in irrigation districts where the quantity or quality of surface water can be affected. Deep vadose zones and perched water tables can complicate the modelling of these fluxes, and model outputs may be biased if these factors are misrepresented or ignored. This study was undertaken in the Murray Basin in southern Australia to develop and test an integrated modelling method that links irrigation activity to surface water impacts by accounting for all key hydrological processes, including perching and vadose zone transmission. The method incorporates an agronomic water balance to simulate root zone processes, semi-analytical transfer functions to simulate the deeper vadose zone, and an existing numerical groundwater model to simulate irrigation returns to the Murray River and inform the management of river salinity. The integrated modelling can be calibrated by various means, depending on context, and has been shown to be beneficial for management purposes without introducing an unnecessary level of complexity to traditional modelling workflows. Its applicability to other irrigation settings is discussed.

scholarly journals Stormwater harvesting in ephemeral streams: how to bypass clogging and unsaturated layers

2021 ◽  
Author(s):  
José D. Henao Casas ◽  
Fritz Kalwa ◽  
Marc Walther ◽  
Randolf Rausch
Keyword(s):  
Vadose Zone ◽  
Numerical Models ◽  
Water Storage ◽  
Sensitivity Analyses ◽  
Ephemeral Streams ◽  
Infiltration Rates ◽  
Stormwater Harvesting ◽  
Harvesting Systems ◽  
Study Case ◽  
Recharge Rates

AbstractTo cope with water scarcity in drylands, stormwater is often collected in surface basins and subsequently stored in shallow aquifers via infiltration. These stormwater harvesting systems are often accompanied by high evaporation rates and hygiene problems. This is commonly a consequence of low infiltration rates, which are caused by clogging layers that form on top of the soil profile and the presence of a thick vadose zone. The present study aims to develop a conceptual solution to increase groundwater recharge rates in stormwater harvesting systems. The efficiency of vadose-zone wells and infiltration trenches is tested using analytical equations, numerical models, and sensitivity analyses. Dams built in the channel of ephemeral streams (wadis) are selected as a study case to construct the numerical simulations. The modelling demonstrated that vadose-zone wells and infiltration trenches contribute to effective bypassing of the clogging layer. By implementing these solutions, recharge begins 2250–8100% faster than via infiltration from the bed surface of the wadi reservoir. The sensitivity analysis showed that the recharge rates are especially responsive to well length and trench depth. In terms of recharge quantity, the well had the best performance; it can infiltrate up to 1642% more water than the reservoir, and between 336 and 825% more than the trench. Moreover, the well can yield the highest cumulative recharge per dollar and high recharge rates when there are limitations to the available area. The methods investigated here significantly increased recharge rates, providing practical solutions to enhance aquifer water storage in drylands.

Paleoanthropology: Pliocene and Pleistocene human evolution

Paleobiology ◽  
1981 ◽  
Vol 7 (3) ◽  
pp. 298-305 ◽  
Author(s):  
Eric Delson
Keyword(s):  
Human Evolution ◽  
Eastern Africa ◽  
Integrative Approach ◽  
New Developments ◽  
Recent Advances ◽  
Temporal And Spatial ◽  
Evolutionary Aspects

Modern paleoanthropology is broadly interdisciplinary, integrating the results of studies in hominid (or more generally primate) paleontology, morphology and systematics with archeology, stratigraphy, chronometry, general paleontology, taphonomy and ecology, among other fields. (I here employ the term “hominid” to include all advanced hominoids of Miocene to Pleistocene age, following Delson and Andrews, 1975; similarly “hominine” (or “human”) refers to members of the subfamily Homininae of this usage, especially Australopithecus and Homo. Many other authors restrict hominine/human to Homo alone, employing hominid where I use hominine.) This integrative approach has been both spectacular and successful in eastern Africa (see Laporte 1980), due to the influence of F. C. Howell, the Leakeys and their colleagues, but it has also been responsible for recent advances in other temporal and spatial intervals in human evolution. In this review, I will concentrate on the morpho-evolutionary aspects of recent paleoanthropological studies, indicating major sources and new developments. Most fossils not otherwise referenced are discussed, albeit often with a different interpretation, in Wolpoff's (1980a) text.

AUTOMATIC SAMPLING OF PERCHED WATER FROM VADOSE ZONE SHALLOW WELLS

1998 ◽  
Vol 14 (4) ◽  
pp. 399-406
Author(s):  
N. R. Rainwater ◽  
R. E. Yoder ◽  
J. B. Wilkerson ◽  
B. D. Russell
Keyword(s):  
Vadose Zone ◽  
Perched Water ◽  
Automatic Sampling ◽  
Shallow Wells

Numerical analysis of one-dimensional decay of a perched water table

1978 ◽  
Vol 36 (1-2) ◽  
pp. 109-119 ◽  
Author(s):  
K.K. Watson ◽  
F.D. Whisler ◽  
A.A. Curtis
Keyword(s):  
Numerical Analysis ◽  
Water Table ◽  
One Dimensional ◽  
Perched Water ◽  
Perched Water Table

scholarly journals Modelling the Effect of Efficiency Measures and Increased Irrigation Development on Groundwater Recharge through a Deep Vadose Zone

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 936 ◽  
Author(s):  
Glen R. Walker ◽  
Dougal Currie ◽  
Tony Smith
Keyword(s):  
Numerical Model ◽  
Vadose Zone ◽  
Time Delays ◽  
Total Change ◽  
Initial Development ◽  
Irrigation Development ◽  
Soil Layers ◽  
Efficiency Measures ◽  
Water Tables ◽  
Individual Actions

Water use measures are being implemented in irrigation areas to make better use of limited water resources and reduce adverse environmental impacts. A semi-analytical model is developed and tested with a numerical model to estimate changes in timing and magnitude of recharge from such measures in irrigation areas to support management of impacts, especially for areas with deep vadose zones and perched water tables. Low hydraulic conductivity of soil layers will lengthen time delays between actions and changes to recharge in addition to limiting the maximum recharge. Despite variations in detailed processes, the recharge outputs from models are surprisingly similar, irrespective of whether lateral effects are major. Superposition may be used to simplify the modelling of the total change in recharge from successive actions, including the initial development. Further simplification is possible, using an exponential conceptual model to approximate recharge responses to individual actions.

Perched Water Tables on Argixeroll and Fragixeralf Hillslopes

2001 ◽  
Vol 65 (3) ◽  
pp. 805-810 ◽  
Author(s):  
P.A. McDaniel ◽  
R.W. Gabehart ◽  
A.L. Falen ◽  
J.E. Hammel ◽  
R.J. Reuter
Keyword(s):  
Perched Water ◽  
Water Tables

scholarly journals Compound flood modelling framework for rainfall-groundwater interactions

2021 ◽  
Author(s):  
Francisco Peña ◽  
Fernando Nardi ◽  
Assefa Melesse ◽  
Jayantha Obeysekera ◽  
Fabio Castelli ◽  
...  
Keyword(s):  
Water Table ◽  
Flood Risk ◽  
Numerical Models ◽  
Absorption Capacity ◽  
Subsurface Water ◽  
Climate Projections ◽  
Exchange Flow ◽  
Storm Events ◽  
Modelling Framework ◽  
Water Tables

Abstract. Compound floods are an active area of research where the complex interaction between pluvial, fluvial, coastal or groundwater flooding are analyzed. A number of studies have simulated the compound flooding impacts of precipitation, river discharge and storm surge variables with different numerical models and linking techniques. However, groundwater flooding is often neglected in flood risk assessments due to its sporadic frequency - as most regions have water tables sufficiently low that do not exacerbate flooding conditions -, isolated impacts and considerably less severity in respect to other types of flooding. This paper presents a physically-based, loosely-coupled modelling framework using FLO-2D and MODFLOW-2005 that is capable to simulate surface-subsurface water interactions to represent compound flooding events in North Miami. FLO-2D, responsible of the surface hydrology and infiltration processes, transfers the infiltration volume as recharge to MODFLOW-2005 until the soil absorption capacity is exceeded, while MODFLOW-2005 return exchange flow to the surface when groundwater heads are higher than the surface depth. The model calibration is based on three short-lived storm events that as individual processes represent minimum flooding conditions but in combination with pre-existing high-water table levels results in widespread flooding across the study area. Understanding groundwater flood risk is of particular interest to low-elevation coastal karst environments as the sudden emergence of the water table at ground surface can result in social disruption, adverse effects to essential services and damage infrastructure. Results are validated using FEMA’s severe repetitive loss (SRL) property records and crowdsourced data. Further research should assess the exacerbated impacts of high tides and sea level rise on water tables under current and future climate projections.

scholarly journals Perched-Water Evaluation for the Deep Vadose Zone Beneath the B, BX, and BY Tank Farms Area of the Hanford Site

2013 ◽  
Author(s):  
Michael J. Truex ◽  
Martinus Oostrom ◽  
KC Carroll ◽  
Glen B. Chronister
Keyword(s):  
Vadose Zone ◽  
Hanford Site ◽  
Perched Water
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