Monday, 5 December 2011

Guest Blog - The Importance of Groundwater Monitoring

The latest in our series of guest blogs is an article on the importance of groundwater monitoring, written by Richard Boak, an independent hydrogeologist. Richard has over 30 years of hydrogeological experience, and has done much of his work internationaly with a strong focus on Africa.  

"I attended the launch in London recently of a joint publication from the Institution of Civil Engineers, Oxfam GB and WaterAid entitled “Managing Water Locally”, which encourages water resource management to take place at local or community level. I was very pleased to see that the report also emphasises the importance of long-term monitoring of key parameters such as rainfall, groundwater levels and water abstraction. This is a subject close to my heart – I’ve lost count of the number of times in my career that I’ve wished that basic monitoring data were available. When called in to advise on why groundwater levels are falling, why a well has dried up, or how deep should a new borehole be drilled, then several obvious questions raise themselves. What is the normal seasonal behaviour of the groundwater levels in this area? How often does the well dry up? What are the highest and lowest groundwater levels that have been observed? What is the typical difference between the rest water level and the pumping water level, for different pumping rates? Has the pattern of groundwater abstraction changed recently (increased consumption, for example, or new abstractions elsewhere exploiting the same aquifer)? All of these questions can be answered fairly easily with some good monitoring data, and the longer the data record, the better. Without this information, we are working in the dark, and the risk of a groundwater source failing to live up to expectations rises enormously.

So please, if you are involved in planning a new water supply scheme, or rehabilitating an existing groundwater source, start collecting data now (to paraphrase the proverb: the best time to start monitoring groundwater is twenty years ago; the second-best time is now). Make sure you include access for monitoring equipment in the design of headworks for boreholes and wells (this is not complicated, and is usually as simple as a well-placed hole with removable cover). Involve the local community in collection of data, and ensure that people are trained and equipped to continue monitoring after you drive away. Run some simple quality-control checks on the data before archiving. Use the data, so that you and your successors gain an understanding of how the groundwater system is behaving. Of course, groundwater monitoring is not without its pitfalls, and bad data can be worse than no data. If you’re unsure, get advice from an experienced hydrogeologist on where, what, how and when (how often) to monitor."

Richard has also recently authored a fascinating account of Richard Thornton, a geologist who accompanied David Livingstone on his explorations of Africa, which many of you may be interested in reading.