The Growing Value of Ground Water Supplies

The writer wishes to call the attention of members to the fact that as the population in any district increases annually and the troubles from contamination necessarily grow worse, the intrinsic value of ground water supplies increases correspondingly. The natural growing troubles due to density of population have led many large cities in Europe, as well as this country, to abandon their old surface water supplies, and they have gone back to the old original ground water supplies as being the best and safest and this conclusion has been reached after long years of sad experience. It is true that ground water supplies are surrounded by grave doubts as to their capacity in a long season of protracted drought. The sum and substance of the whole business is this, that in all such cases the best teacher is broad experience. This teaches us that in cases where you have ample capacity of gravel beds to store up the available waters, the maximum supply possible, in any case, will be 25 to 30 per cent of the long average rainfall. In a great many cases, however, the capacity of the gravel beds is inadequate to store up and hold all the available waters and as a final result you will only get the volume of water that the gravel beds will naturally hold and no more. Hence it is that in a great many cases you only get 8 to 10 per cent of the average rainfall, simply because your gravel beds are not large enough to hold all the available waters. In arriving at the volume of storage in the gravel beds a great deal of conservatism should be exercised. After you have carefully figured out the total volume of the gravel beds, then assume that half of this will be lost by reason of underground topography, then assume that the voids in the balance will be one third, hence we have ' X ' = ' the total volume of gravel beds is available for storage of water and ' average rainfall is the maximum water available.