Hydro-ecology

Hints and Tips

1. Agree your objectives and how they should be met

Just as every site is different, so is every hydro-ecological investigation. Without clearly defined objectives many of your surveys may be of little use to your primary objective and at the end of the day you may not have the crucial information that you need.

This is particularly important if the information is part of a risk assessment or an environmental impact assessment with tight planning deadlines.

It is also important if you have a limited budget and wish to make a best approximation to the solution within a limited time-scale or financial constraints.

It is only with clearly defined objectives and methodology that those that come after you will be able to understand your project and interpret the data themselves.

2. Survey only what you need to survey

Unless you are undertaking a research project with unlimited time and computer facilities, keep your surveys limited to those needed to answer your questions. Surveys for the sake of them will accumulate a great mass of data which may take ages to sort out and delay the drawing together of conclusions.

If in doubt, undertake an initial reconnaissance. Acidic valley mire systems are often exceedingly complex and surveys may need to be quite detailed. In contrast, sites with neutral or alkaline catchments are often much more uniform and need far less input. Unless of course there are obvious signs of pollution or other adverse impacts from development for instance.

It may not be necessary to undertake deep drilling to determine water tables. For instance, if the substrates below and around your site are not permeable you may not have a water table to measure. Your expensive boreholes may not tell you much.

3. Be careful with your dipwells

Dipwells can be relatively simple to put in, but be sure to record the strata they are inserted into so that those that come after you know what they are dealing with.

Remember that a dipwell will only tell you what you want to know if you read the water level in it on a regular basis for at least a full year. Failure to read your dipwells means that all of the effort of putting them in will have been wasted.

In areas with high groundwater, monthly readings may be appropriate. In seasonally waterlogged land, you may need to read them every week and be careful about the weather conditions at the time.

Remember, dipwells record what is going on in the rooting zone of the vegetation. Read the level from the top of the ground, not from the bottom of the dipwell.

4. One dipwell or many?

A single dipwell into clayey soils will provide you with different information to a dipwell in permeable soils with high groundwater. Putting in three dipwells each to a different depth at the same location (within a metre of each other) will tell you far more than a single dipwell will if the soils have slowly permeable layers. Try putting in three such triples at 20m apart and see if they all tell the same story - if they do not, you will have to think very carefully about the complexity they are recording.

5. Be holistic

Hydro-ecology is the sum of all of the physical and biological factors that support the fauna and flora of the site.

Knowledge of water flows is of little use without an understanding of soil and geological conditions. A knowledge hydrogeology may be of little use if its connection with soil water regimes is not understood.

Remember that engineering hydrology used for many development projects may be off little use in understanding wildlife habitats. Similarly, descriptions of soils from trial pits dug for engineering purposes may not tell you what you want to know about soil water regimes.

6. Be in control

Define your own objectives and your time scale, decide for yourself the investigations necessary (or take expert advice) and take nothing less. If you do, you may well be wasting valuable time and money and may not achieve your objectives.