Impossible to determine the direction of groundwater without piezometric data

Yasmina Bouroubi

Topography and contact springs can give any degree of solution at least in scale dependent but not accurate.

You might be interested in Toth, 1962 as conceptual.

Article A Theory of Groundwater Motion in Small Drainage Basins in C...

But as suggested, there may be indicators, but data is needed. If you have a specific area of interest, there might be some data or general groundwater maps developed by geologists or hydrogeologists. The actual direction is generally assumed to be perpendicular to the pieziometric contours, but underground substrates, layers, fractures, etc. are seldom uniform, potentially affecting local direction and rates of movement. Streams may also give some insight from the local water levels on banks, and the hyporheic zone is a zone of surface, groundwater interchange, recharge, etc. Other general, but non-specific indicators might include wetlands, hydric soil indicators, hydrophytic plants presence, riparian or floodplain boundaries. And features such as jack strayed trees (leaning in multiple directions), J shaped trunks suggesting soil slippage or instability are some of the features found in ground surveys that suggest the unstable or earthflow soils with intermittent or permanent high water table issues. I mentioned some of my experiences in the conference paper.

Conference Paper Watershed Restoration after Calamity

If you have data on depth to water table in hand dug wells and elevation above mean sea level, you can generate your static water level and plot it on suffer software to get flow direction

If you have data on depth to water table in hand dug wells and elevation above mean sea level, you can generate your static water level and plot it on suffer software to get flow direction

Ernest Akudo,

I know. I added a question without the available data as you see in the question title. Your answer is not answer of this question. I recommend William F. Hansen's reply.

Accurately, groundwater flow direction can only be determined by measuring the groundwater level, however hypothetically we can estimate groundwater flow (especially groundwater flow in the phreatic aquifer) with a topographic approach.

La meilleure façon pour déterminer le sens d'écoulement des eaux dans les aquifères est la prise des mesures du niveau piézométrique dans les puits, si ces mesures sont impossibles, l'estimation de l'écoulement peut avoir lieu avec un degré de certitudes faibles par rapport à celui des piézométrie en faisant un étude structurale approfondie faisant intégrer les pendages et les fracturation ... ( modélisation structurale). Il est à noter que la modélisation structurale est plus difficile que la levée piézométrique, mais c'est aussi une solution théorique.

Hello Can Ertekin,

This is a good inquiry. I think under specific conditions you can guess the groundwater flow based on the topography.

The following paper could reply to your question:

Article Are Water Tables a Subdued Replica of the Topography?

Good luck!

Mohamed Ouarani

Thank you for your sharing.

My pleasure Can Ertekin.

I am not sure if you are aware about the following project:

https://www.magnet4water.com

It could be of interest for you.

When data on water level is not available, hydrochemistry can be used to deduce a simplified model for groundwater flow, based on the fact that groundwater dynamics usually influence ground water chemistry; where salinity distribution of groundwater is usually influenced by the location or the past movement of the groundwater, under the control of many chemical and physical factors, such as thee rock mineralogy, groundwater velocity and others along the pass.

As groundwater moves along its flow paths in the saturated zone, increases of total dissolved solids and most of the major ions normally occur. As would be expected from this generalization, it has been observed in groundwater investigations in many parts of the world that shallow groundwater in recharge areas is lower in dissolved solids than the water deeper in the same system and lower in dissolved solids than water in shallow zones in the discharge areas.

In a classic paper based on more than 10,000 chemical analyses of well samples from Australia, Chebotarev (1955) concluded that groundwater tends to evolve chemically toward the composition of seawater. He observed that this evolution is normally accompanied by the following regional changes in dominant anion species:

Travel along flow path →

HCO3- → HCO3- + SO4-2 → SO4-2 + Cl- → Cl- + SO4-2 → Cl-

Increasing age →

These changes occur as the water moves from shallow zones of active flushing through intermediate zones into zones where the flow is very sluggish and the water is old. This sequence, like many others in the geological sciences, must be viewed in terms of the scale and geology of the specific setting, with allowances for interruption and incompletion.

For more details about this concept can be found in literature about grondwater hydrochemistry.

The most simple approach to represent groundwater flow directions, in one single aquifer unit, is by generating contour maps of total dissolved solids, electrical conductivity, or dissolved chloride contours. Frequently those contours mimic groundwater flow directions with reasonable accuracy. The main issue with this approach arises from installations with long screens tapping multiple aquifers. Good luck!

The acquisition of the mineral load for a groundwater most often follows the flowpath (from the recharge zone = less mineralized water, towards the discharge zone = most mineralized water).

Plotting isolines of groundwater chloride contents will give you a good idea of the flow directions for your investigated aquifer. Chloride being a conservative ion, it does not react with any other elements along the flowpath and is the best environmental tracer in such a case.

Moreover, plotting EC (or TDS) isolines could also give you roughly the same maps for flow directions.

Hope this would help. Good luck !

Flownet analyses approch is ideal to work out groundwater flow direction : ie use of groundwater level data plot with reference to the datum. One can visualize groundwater flow direction on basis of information on subsurface aquifer system disposition, it's relation with topographic features, drainage patterns etc other geomorhic features of the terrain. Assuming there is increase in chemical load along flow direction, information on chemical analysis also helpful to decipher groundwater flow direction...

I can categorize six possible ways (if we are talking about shallow phreatic aquifers not captive ones):

1) Self-Potential Electro-Magnetic technique: this method is general shows negative SP values (-50mV) at recharge zone and positive values (+50mV) at discharge zone. Electromagnetic methods can help a lot in this issue.

2) Time-lapse microgravity measurements: Also, we measure the microgravity at two different stations above the study area (if the topography is corrected or plane), the values should be high at shallow water table and low at deep water table (this is not 100% true because the geology can change this basic assumption).

3) The chemistry of waters: in general when the water flows, its chemistry is increasing due to contact with surrounding rocks with time.

4) The topography can give us also some information as the water table in general follows the shape of topography. Here also we have to be careful as geology and porosity/permeability of rocks if they change, they can affect this point.

5) You have to check some recent remote sensing techniques applications for shallow aquifers, they can give some interesting information.

6) You have to check if there are springs, discharges around the study area, this can give you some information on recharge and discharge zones.

I suppose that using hydrogeochemical characteristics for the evaluation of groundwater flow direction is not a reliable approach. Indeed, concentrations of SO4, Cl, and TDS value increase from recharge to discharge zone. However, it is an ideal situation when groundwater changes chemical types sequentially from HCO3 to SO4 and then to Cl with TDS growth. It should be a regional aquifer presented by aluminosilicate rocks with a low rate of water exchange. The chemical composition of groundwater should be analyzed based on borehole sampling because, in wells and springs, it may be interfered with atmospheric precipitation. Salt inclusions will also mess the “ideal” sequence of groundwater chemical composition changes (from HCO3-Ca to Cl-Na). As for shallow aquifers, they are subjected be an anthropogenic load, which drastically changes groundwater chemical type even up to such exotic types as Cl-NO3 with a prevalence of K among cations. Additionally, they usually have a wide recharge area, i.e., dilution by precipitation exists throughout all aquifer distribution area. Sometimes, shallow groundwater is subjected by evaporation in an arid zone. This changes its chemical composition to SO4 type despite time of movement and water-rock interaction. Too many factors affect water chemistry, and you should take into account all of them to get reliable results. Topography and geomorphology seem to be more suitable for groundwater flow direction.

Thank you for interesting question. I attempt to estimate a change of the underground water direction based at the result of the precise monitoring of tide waves. Please, see attachement. Best regards, Ella.

The temperature time series can also provide information on both groundwater derection and flow rate. See,

• Liu, Q.Y., Chen, S.Y., Jiang, L.W., Wang, D., Yang, Z.Z., Chen, L.C., 2019. Determining thermal diffusivity using near-surface periodic temperature variations and its implications for tracing groundwater movement at the eastern margin of the Tibetan Plateau. Hydrological Processes. 33(8), 1276-1286.
• Kurylyk, B.L., Irvine, D.J., 2019. Heat: An overlooked tool in the practicing hydrogeologist's toolbox. Groundwater. 57(4), 517-524.

I recommend that you look at the topography as this influences in some way the hydraulic gradient line.

You can measure directional properties either in wells or by installation of flux meters in the subsurface directly.

Groundwater Flow Direction are dynamic aspect of aquifers system defined / under consideration. Aquifer disposition and its parameters, like transmissivity - hydraulic conductivity etc are basic factors along with head difference's across the area. In general, GW flows from high to lower head side. Some pockets of intensive development cause lowering the piezometric head in semiconfined / confined aquifer system and it may alter groundwater flow direction which is aberrant to general regional flow pattern.

A Particle Fluxmeter Device is i.e. http://phrealog.de/. I used it myself, bt the flow directions were not really steady-state. I recommend using a "long term" measurement over a couple of days.

I don't know, but if you find out, please share! A standard answer is that the phreatic surface (water table) is a flattened version of the surface topography. I accept that, as a starting point, but then think we need to look at surface water bodies as breakout points where the phreatic surface surfaces. So even without wells, you have observations of the phreatic surface in the form of lakes and rivers. I have no idea how to generalise the approach. If I had time and remembered MODFLOW, I'd build a single layer aquifer model with real world topography and mean annual water levels in rivers and just apply uniform areal recharge to the model to see where the water goes in steady state, and where the flattened surface topography concept works and where it doesn't.