This new research should help HGS users to select a suitable method for the spatial distribution/interpolation of precipitation data at different scales. The study evaluates three different methods of spatially distributing precipitation data – including Thiessen Polygons (TP), Co-Kriging (CK) and Simulated Annealing (SA) - at two different watershed scales using HydroGeoSphere.
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HGS RESEARCH HIGHLIGHT – The Response of the HydroGeoSphere Model to Alternative Spatial Precipitation Simulation Methods
HGS RESEARCH HIGHLIGHT – Simulating preferential flow and snowmelt partitioning in seasonally frozen hillslopes
AUTHORS: Aaron A. Mohammed, Edwin E. Cey, Masaki Hayashi, Michael V. Callaghan
This research highlights the ability to model pore-water freeze/thaw and how it impacts the partitioning of snowmelt into infiltration, runoff and groundwater recharge in seasonally frozen hillslopes.
This research follows on an earlier highlight by author Aaron Mohammed about the development of a dual-permeability model which integrates the effects of soil freeze-thaw and preferential flow on infiltration and runoff generation in structured soils. This formulation was incorporated successfully into HydroGeoSphere. Read the original research highlight here.
The infiltrability of frozen soils strongly influences snowmelt partitioning and redistribution in cold regions. Preferential flow in frozen soil can enhance infiltration, but dynamics are complicated by coupled water and heat transfer processes as well as landscape conditions prior to and during snowmelt.
Model simulations in HydroGeoSphere, based on hydrological functioning and landscape properties of the Canadian Prairies, were used to evaluate a dual-domain (matrix and macropore) formulation of variably-saturated flow in frozen soils, with distinct water and heat transport regimes in each domain.
Two-dimensional hillslope simulations were able to capture the landscape hydrologic response to snowmelt fluxes observed in the Prairies and similar landscapes, specifically: (1) enhanced infiltration into frozen soil due to preferential flow, (2) refreezing of infiltrated water and its effect on the evolution of runoff generation in frozen soils, and (3) groundwater recharge prior to ground thaw. Results showed that multiple meltwater input events progressively decreased frozen soil infiltrability and increased runoff generation. Simulations demonstrated that refreezing of infiltrated water along preferential flowpaths is an important process governing the timing and magnitude of both runoff generation and groundwater recharge in frozen soils, but that this behaviour can be highly counterintuitive and depends on soil structure. The modeling framework provides a physically-based approach for describing these interacting preferential flow and soil freezing processes at the hillslope scale needed to simulate the hydrologic functioning of seasonally frozen landscapes.
HGS RESEARCH HIGHLIGHT – Storm Surges and Coastal Salinization/Saltwater Intrusion
This week’s research highlight introduces two papers by Dr. Holly Michael’s research group at the University of Delaware – papers which bring attention to the impact of storm surges on coastal salinization/saltwater intrusion under a changing climate, and on the subsequent impact of saltwater flooding on crop-yields in adjacent agricultural lands.
Dr. Holly Michael (firstname.lastname@example.org) is corresponding author for both papers.
Paper #1: Effects of Marsh Migration on Flooding, Saltwater Intrusion, and Crop Yield in Coastal Agricultural Land Subject to Storm Surge Inundation
AUTHORS: Julia A. Guimond and Holly A. Michael
Abstract: Low-lying coastlines are vulnerable to sea-level rise and storm surge salinization, threatening the sustainability of coastal farmland. Most crops are intolerant of salinity, and minimization of saltwater intrusion is critical to crop preservation. Coastal wetlands provide numerous ecosystem services, including attenuation of storm surges. However, most research studying coastal protection by marshes neglects consideration of subsurface salinization. Here, we use two-dimensional, variabledensity, coupled surface-subsurface hydrological models to explore how coastal wetlands affect surface and subsurface salinization due to storm surges. We evaluate how marsh width, surge height, and upland slope impact the magnitude of saltwater intrusion and the effect of marsh migration into farmland on crop yield. Results suggest that along topographically low coastlines subject to storm surges, marsh migration into agricultural fields prolongs the use of fields landward of the marsh while also protecting groundwater quality. Under a storm surge height of 3.0 m above mean sea level or higher and terrestrial slope of 0.1%, marsh migration of 200 and 400 m protects agricultural yield landward of the marshfarmland interface compared to scenarios without migration, despite the loss of arable land. Economic calculations show that the maintained yields with 200 m of marsh migration may benefit farmers financially. However, yields are not maintained with migration widths over 400 m or surge height under 3.0 m above mean sea level. Results highlight the environmental and economic benefits of marsh migration and the need for more robust compensation programs for landowners incorporating coastal wetland development as a management strategy.
Paper #2: Storm Surges Cause Simultaneous Salinization and Freshening of Coastal Aquifers, Exacerbated by Climate Change
AUTHORS: Anner Paldor and Holly A. Michael
Abstract: Ocean surge events are known to threaten coastal aquifers through vertical infiltration, with the degree of salinization depending on hydrogeologic factors. Another salinization process in coastal aquifers is lateral saltwater intrusion, which may also be affected during surges as the inundation alters the aquifer hydraulic heads. While these processes have been considered individually, here we consider the interplay between them and the longer-term impact of climate change, which is projected to increase the frequency of surges in the future. Using numerical modeling, the location of the lateral freshwater-saltwater interface and the total salt storage are calculated for single and repetitive surge events with different recurrence times to predict the long-term effect of surges. Results point to two novel mechanisms: (1) Following a single overwash event, salt storage in the aquifer peaks due to vertical salinization, and a second, lower peak occurs on a longer time scale. This second peak is due to the surge-induced rebound motion (seaward and then landward) of the interface. (2) The projected increase in surge frequency due to climate change can potentially induce long-term migration of the interface seaward, independent of a change in sea level, depending on the aquifer permeability. Together with this freshening effect, the total salt load in the aquifer increases due to repetitive vertical salinization. Thus, we show for the first time the combined effect of storm surges and climate change on both vertical and horizontal movement of salt in coastal aquifers, with important implications for water management along global coastlines.
HGS RESEARCH HIGHLIGHT – Development of an integrated numerical flow model in the Prairie Environment
AUTHORS: Arefin Haque, Amgad Salama, Kei Lo, Peng Wu
A recent publication by researchers at the University of Regina uses HydroGeoSphere to investigate the impact of climate variability and different groundwater withdrawal scenarios on groundwater levels in the Leech Lake aquifer. This paper provides an excellent introduction to the use of HGS in semi-arid prairie regions, making use of the built-in evapotransporation and snowmelt processes to estimate overall recharge rates under various climate scenarios (including extreme drought).
“The interaction between surface water and groundwater is complicated due to the existence of many factors, such as uncertainty of land cover and aquifer properties, which can cause substantial errors in model output (Eslamian and Nekoueineghad, 2009; Sophocleous, 2010; Straatsma et al., 2013). A fully-integrated, physically-based numerical model is well capable of handling these factors (Alaghmand et al., 2014). HydroGeoSphere (HGS), fully integrated model has been selected for this research because of its capability to address some of these complexities while considering a large scale study (Therrien, 2011). HydroGeoSphere can simulate the dynamic interactions between all sub-domains at each time step.”
“In HGS, rainfall precipitation is branched into components such as evapotranspiration, runoff and infiltration. HGS allows for the computation of water infiltration or exfiltration between rivers, lakes and aquifers. These interactions play a significant role in the prediction of future scenarios with respect to climate change, since recharge (precipitation, snowmelt) is very susceptible to climatic fluctuations.”
This study was co-authored by researchers at the University of Regina (Faculty of Engineering and Applied Science) and the Saskatchewan Water Security Agency. For more information, please contact the corresponding author Peng Wu (Assistant Professor and Program Chair, Environmental Systems Engineering; Peng.Wu@uregina.ca).
Study focus: Groundwater and surface water interactions have been conducted numerically for bringing out a sustainable management of the Leech Lake aquifer in the southern portion of City of Yorkton area within the province of Saskatchewan, Canada. The aquifer is composed of highly conductive sediments over bedrock strata with low hydraulic conductivity. A fully coupled, physically based surface-groundwater flow model using HydroGeoSphere (HGS) is developed for the purpose of simulation. In this numerical model, different withdrawal scenarios and the effects of climate variabilities (precipitation and snowmelt) are being conducted to investigate the impact of water usage on groundwater level.
Fig. 4. (a) 2-D mesh for overland flow (surface domain); (b) a slice of 3-D mesh for subsurface domain.
New hydrological insights for the region: Groundwater from several aquifers serves as the main water supply for the city of Yorkton. Aquifer protection and sustainable use of the limited resource is of utmost importance to the municipality and in support of economic development in the region. Insight and understanding of the risks and impact to the municipal groundwater supply is required. To address the sustainability of the aquifers in the area, a numerical model was developed to provide greater comprehension of the surface and groundwater fluxes. Model calibration and validation was completed with existing long term monitoring information from piezometers in the area. In the semi-arid environment of the Prairie Provinces, water withdrawal and precipitation plays a significant role in affecting groundwater level. Different withdrawal scenarios are conducted to investigate the impact of the water usage on the Leech Lake aquifer that will provide a tool to support the development of a sustainable management plan. Precipitation as well as snowmelt have been incorporated into the model to identify the driving recharge factor for groundwater variation. Temporal and spatial variabilities, as well as estimation of magnitude for exchange flow rates at the interfaces are presented. The fully integrated model developed in this study provides the foundation for future groundwater management applications in climate driven changes within the Prairie environment.
Fig. 5. Overland flow (surface) domain at the finishing time of the simulation period of 14 years; (a) elevation contours, Z and (b) water depth contours.
Fig. 16. Relative comparison and major recharge factor identification between precipitation and snowmelt for the entire simulation period (2002–2015).
HGS RESEARCH HIGHLIGHT – Fully Coupled Surface–Subsurface Hydrological Modeling to Optimize Ancient Water Harvesting Techniques
AUTHORS: Wim M. Cornelis, Koen Verbist, Tesfay Araya, Emmanuel Opolot, Jasmien C.J. Wildemeersch, and Bashar Al-Barri
We’re so proud that an entire chapter in the recently published “Handbook of Water Harvesting and Conservation: Case Studies and Application Examples” is dedicated to the modeling of ancient water harvesting techniques using HydroGeoSphere. In this chapter HGS was used to evaluate and optimize rain harvesting techniques across four case studies. Two of these case studies were from Chile, while the other two were in Ethiopia and Niger. The Chilean case studies evaluated the effectiveness of infiltration trenches (zanjas) in reducing surface runoff losses, promote recovery of natural vegetation and reduce land degradation. “In Ethiopia, the model was used to evaluate and optimize conservation practices with broad and narrow permanent beds, which are modified versions of locally called terwah and derdero systems.” And in Niger HydroGeoSphere models were used to evaluate several water harvesting techniques “include[ing] scarification, zaï pits, and microcatchments like semi-circular or half-moon bunds (demi lunes)”.
The study demonstrates clearly the benefits of integrated hydrologic modeling in the evaluation of various water harvesting and conservation techniques.
“With [HydroGeoSphere] being originally developed to simulate surface–subsurface water flow and solute transport at a larger watershed scale, this chapter describes the first attempts to apply it for evaluating and improving water harvesting techniques at the field and small watershed scale. Whereas water harvesting studies are often based on a trial and error approach or at best on an empirical approach, the approach presented here has many advantages and provides a better understanding of water flow processes at or near water harvesting techniques.”
This study was co-authored by researchers at UNESCO, Ghent University, University of Fort Hare and Makerere University. For more information please reach out to the main author Wim Cornelis (Professor in Agro-Environmental Soil Physics at Ghent University; email@example.com).
HGS RESEARCH HIGHLIGHT - 8 Projects from the European Geosciences Union 2021 General Assembly
Aquanty is so pleased to see the volume of high quality research being conducted using HydroGeoSphere.
This years annual general assembly of the European Geosciences Union featured eight (8!) presentations based on HydroGeoSphere projects from researchers around the world, including: Poland, France, China, Germany, Switzerland, Oman, Italy and (of course) Canada. For more information about any of these projects click on the titles below for abstracts and author info:
If you have conducted research of your own with HydroGeoSphere we would be thrilled to highlight it here on our blog. Please send research submissions to firstname.lastname@example.org.
HGS RESEARCH HIGHLIGHT – Hydraulic tomography analysis of municipal-well operation data with geology-based groundwater models
AUTHORS: Xin Tong, Walter A. Illman, Steven J. Berg & Ning Luo
This study is focused on the estimation of aquifer parameters (e.g. hydraulic conductivity and specific storage) through inverse modeling of water-level data from observation wells collected during municipal well operations. The data is tested using four different conceptual geological models in HydroGeoSphere coupled to PEST, and the results indicate that this is a viable method of estimating reliable parameter values using existing data sets (providing a valuable new dimension to data collected during municipal well operations).
This study was co-authored by Steve Berg (Aquanty CEO and Principle Hydrogeologist) and Walter Illman (Scientific Advisor to Aquanty). If you would like to learn more about this paper please reach out to email@example.com.
The sustainable management of groundwater resources is essential to municipalities worldwide due to increasing water demand. Planning for the optimized use of groundwater resources requires reliable estimation of hydraulic parameters such as hydraulic conductivity (K) and specific storage (Ss). However, estimation of hydraulic parameters can be difficult with dedicated pumping tests while municipal wells are in operation. In this study, the K and Ss of a highly heterogeneous, multi-aquifer/aquitard system are estimated through the inverse modeling of water-level data from observation wells collected during municipal well operations.
In particular, four different geological models are calibrated by coupling HydroGeoSphere (HGS) with the parameter estimation code PEST. The joint analysis of water-level records resulting from fluctuating pumping and injection operations amounts to a hydraulic tomography (HT) analysis. The four geological models are well calibrated and yield reliable estimates that are consistent with previously studies.
Overall, this research reveals that: (1) the HT analysis of municipal well records is feasible and yields reliable K and Ss estimates for individual geological units where drawdown records are available; (2) these estimates are obtained at the scale of intended use, unlike small-scale estimates typically obtained through other characterization methods; (3) the HT analysis can be conducted using existing data, which leads to substantial cost savings; and (4) data collected during municipal well operations can be used in the development of new groundwater models or in the calibration of existing groundwater models, thus they are valuable and should be archived.
HGS RESEARCH HIGHLIGHT – Investigating groundwater-lake interactions in the Laurentian Great Lakes with a fully-integrated surface water-groundwater model
AUTHORS: Shu Xu, S.K. Frey, A.R. Erler, , O. Khader, S.J. Berg, H.T. Hwang, M.V. Callaghan, J.H. Davison, E.A. Sudicky
This study used HydroGeoSphere to quantify groundwater exchange with the five Great Lakes under monthly average climate inputs calculated using historical data from 1981–2010. The results indicate that groundwater discharge provides a relatively small component of positive basin supply, with significant seasonal fluctuations due to changes in lake levels and groundwater elevations. Another interesting result is the spatial variability in groundwater exchange, with the the 4-kilometer-wide nearshore lakebed area making a much larger contribution to groundwater/lake exchange than the remaining inner portion of the lakebed area.
This study was authored by past and present Aquanty scientists. If you would like to reach out and discuss please email us at firstname.lastname@example.org.
Modelling groundwater-surface water (GW-SW) interactions at scales of large river basins is a difficult challenge. In this study, a fully-integrated surface water-groundwater model accounting for hydrologic seasonality is developed for the 766,000 km2 Laurentian Great Lakes basin, and applied towards the characterization of groundwater-lake (GW-lake) interactions in the five Great Lakes under monthly normal climatology.
The simulated annual average rates of direct groundwater discharge to Lakes Superior, Michigan, Huron, Erie and Ontario through the combined lakebed and 8 km wide band of shoreline surrounding each lake are 29.0, 38.6, 24.5, 11.9, and 11.6 m3/s, respectively. Thus, direct groundwater discharge accounts for a small component of positive basin supply; ranging from 0.6% for Lake Ontario to 1.3% for Lake Michigan, with an overall average of 0.8% for all lakes combined.
Simulation results demonstrate that GW-lake interactions are strongest nearshore, and vary temporally in response to seasonal fluctuations in both lake levels and terrestrial groundwater levels in nearshore regions. In winter, direct groundwater discharge dominates the GW-lake interactions in both the distal and nearshore lakebed areas. In summer, the combined effects of rising lake levels and lowering terrestrial groundwater levels lead to notable reductions in direct groundwater discharge through nearshore areas. Direct groundwater discharge is also shown to vary spatially, with highest rates associated with areas containing thick Phanerozoic hydrostratigraphy, as opposed to Precambrian basement rock. The results from this study indicate that the Great Lakes primarily act as groundwater receivers, gaining considerable amounts of water directly from the basin’s groundwater system.
HGS RESEARCH HIGHLIGHT – Fully-Integrated Groundwater-Surface Water Forecasting in Two Contrasting Hydrostratigraphic Settings within Southern Ontario
AUTHORS: S.K. Frey (1), O. Khader, H. Zhang (2), G. Stonebridge, D. Steinmoeller, A.R. Erler, A. Taylor, S.J. Berg, E.A. Sudicky
(1) Aquanty, 564 Weber St N. Waterloo, ON, N2L 5C6; email@example.com
(2) Ontario Ministry of Environment, Conservation and Parks, 125 Resources Rd, Toronto, ON
We are happy to see the 2021 Southern Ontario Groundwater Geoscience Forum content is now available online (see below). Aquanty’s Steve Frey presented our latest work associated with the project for a fully integrated groundwater–surface-water model for southern Ontario.
In this presentation we highlight our efforts to couple two watershed scale HydroGeoSphere models with the latest weather forecasts. The results allow us to forecast future groundwater levels and surface water flow rates over the short to medium term (i.e daily to monthly).
Over the course of the 2014 – 2019 Southern Ontario Groundwater Project, a fully-integrated groundwater – surface water model was developed and tested. This regional scale model extends across the Phanerozoic terrain of southern Ontario and localized areas of exposed Precambrian shield, such that the model boundary is coincident with watershed boundaries. The spatially heterogeneous subsurface component of the regional model includes three soil layers, five Quaternary layers, and either eleven or seven bedrock layers for the respective low (coarsely discretized) and high (finely discretized) resolution model versions. Since 2019, work with the regional model has been ongoing, including the development of a derivative set of watershed scale models that utilize the same hydrostratigraphy as the regional model, but are constructed with much higher levels of spatial resolution. The watershed scale models are incorporated into a hydrologic forecasting system that until recently had only been evaluated for its ability to predict short-term surface water flows. However, current efforts are focused on further developing and evaluating the ability of the forecasting system to predict future groundwater conditions, including recharge, discharge, and water table position.
In this presentation, we will discuss the progress that is being made towards the goal of using the platform to provide short term (i.e. 1 to 7 day) and sub-seasonal (i.e. monthly) groundwater forecasts. The watershed regions of particular interest in this work are those that encompass the Quinte and Long Point Region Conservation Authority management areas. While both of these areas are highly susceptible to drought impacts on their groundwater resources, they provide contrasting hydrostratigraphy and hydrologic behavior, which in turn makes them ideally suited for forecast model evaluation and comparison.
In addition to the model focused discussion, we will also show recent developments with the web portal that is designed to disseminate the groundwater (and surface water) forecast information to a broad base of groundwater and surface water stakeholders.
Research Highlight: Dual-permeability modeling of preferential flow and snowmelt partitioning in frozen soils
Dual-permeability modeling of preferential flow and snowmelt partitioning in frozen soils
AUTHORS: Aaron A. Mohammed, Edwin E. Cey, Masaki Hayashi, Michael V. Callaghan, Young-Jin Park, Killian L. Miller, Steven K. Frey
The study highlighted this month introduces a dual-permeability model which integrates the dynamics of soil free-thaw cycles and preferential flow on infiltration and runoff generation in structured soils. This formulation was incorporated successfully into HydroGeoSphere.
The infiltrability of frozen soils modulates the partitioning of snowmelt between infiltration and runoff in cold regions. Preferential flow in macropores may enhance infiltration, but flow dynamics in frozen soil are complicated by soil heat transfer processes. We developed a dual-permeability model that considers the interacting effects of freeze–thaw and preferential flow on infiltration and runoff generation in structured soils. This formulation was incorporated into the fully integrated groundwater–surface water model HydroGeoSphere, to represent water–ice phase change in macropores such that porewater freezing is governed by macropore–matrix heat exchange.
Model performance was evaluated against laboratory experiments and synthetic test cases designed to examine the effects of preferential flow on snowmelt partitioning between infiltration, runoff, and drainage. Simulations were able to reproduce experimental observations of rapid infiltration and drainage behavior due to macropores very well, and approximated soil thaw to an acceptable degree. Simulation of measured data highlighted the importance of macropore hydraulic conductivity, as well as macropore–matrix heat and water transfer, on controlling preferential flow dynamics. Test cases replicated a range of snowmelt partitioning behavior commonly observed in frozen soils, including subsurface conditions that produce rapid infiltration and deeper drainage, the contrast between limited vs. unlimited infiltration responses to snowmelt, and the temporal evolution of runoff generation. This study demonstrates the important influence that water freezing along preferential flowpaths can have on infiltrability and runoff characteristics in frozen soils and provides a physically based description of this mechanism that links infiltration behavior to hydraulic and thermal properties of structured soils.
HydroGeoSphere Research Highlights
At Aquanty we love to see new and innovative approaches to using HGS. With that in mind, we'll be making an effort to regularly highlight new research efforts by the scientists here at Aquanty and those in the wider HGS community.
If you are working on anything special, we'd love to hear about it! Feel free to share your work here.
If you've had any recent publications involving new and exciting ways to use HGS, we'll be happy to promote that innovative research as widely as possible. I hope to post regular research highlights on our blog, to be cross-posted on LinkedIn and the HGS User Community.