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Wells in the Coastal Zone

On coastal zones, some older shallow boreholes existed which did not dry up but could not satisfy the demand due to two different reasons. First, polluted surface water was infiltrating and, secondly, the water table dropped during the dry season, so that too much salt water intruded and lowered the water quality. The target of the new project was therefore to find potable water from aquifers which, on the one hand, are deep enough to be fed through fractures by sufficient amounts of water from higher lying parts of the country and, thus, provide drinking water in acceptable quantity all-year round. On the other hand, the boreholes should not reach too far down in order to avoid any significant salt water intrusion from the nearby sea. In this region, it was not possible to rely only on the geo-electrical measurements. It is certainly possible to establish vertical soil resistivity profiles by means of this technique and to locate the transition from salt water to fresh water. The risk will however exist that brackish water cannot be recognized beforehand with the necessary certainty. In addition, if the measurements are carried out during the rainy season, the conditions may change unfavorably in the dry season.

To solve that problem, Schröter tried to find fracture zones lying as shallow as possible. Some spots, located along these lines of argument, have been once again checked by means of geo-electrical techniques and turned out to be promising. Out of some 80 wells with depths between 6 and 23 m, situated on the coast of Mullaitivu, as many as 72 provided good drinking water, five produced slightly saline water still appropriate for cooking and washing, and only three could not be used due to a too high salt content. In some cases, salty water infiltrating above the actual fresh water zone could be impeded by means of a special casing technique applied during the borehole development.

Summary of Project Phase 1

Just as for the urban water supply of Vavuniya Town it appeared that the first 100 drilling sites, determined by Schröter for wells in the rural areas, could be reasonably well confirmed as being promising by the geo-electric assessments; moreover, the acquired drilling results revealed that in more than 90% of the cases these spots were pinpointed most effectively. These practical experiences and their interpretation were confirmed by the geologist team involved. For this reason, it was then decided to use the dowsing technique almost exclusively for the larger part of the subsequently determined (557) locations of well sites in areas with comparable underground conditions. As most of the desired sites had to be situated in the middle of the most populated and urbanized regions, an optimal use of conventional methods, above all of the geo-electrical technique, would have suffered from a number of perturbation effects which would have led to either considerable complications or practical inapplicability.

The hydrogeological factors which had been determined in the meantime and had allowed a general characterization of the area, constituted of course an important basis for the use of the unconventional procedure; even when the dowsing was exclusively applied, these factors had not at all been neglected and they continued to play an important part for the further work and subsequent, fundamental discussions. In any case, the selected decision with respect to intensive use of the dowsing technique allowed for an impressive optimization of both time and cost inputs into the project. As a consequence, up to 10 drilling points could sometimes be located within one day and handed over to the drilling team. In many cases, the time elapsed between first inspection and selection of a site and subsequent successfully completed pump tests amounted to less than a few days or weeks only.

The effective increase of the success rate due to water detection by means of the dowsing technique continued (and turned out to be well reproducible in later projects performed under varying local conditions). The vast project phase 1 had been implemented in Sri Lanka within a record time of three years and, regarding the prevailing conditions, with a convincing unprecedented success. Apart from the establishment of effective sanitary measures, some 691 drillings had been carried out, of which 34 were related to the town of Vavuniya and 604 were equipped with hand pumps and handed over in operating conditions to the different villages of Vavuniya and Mullaitivu Districts (the difference of 53 drillings will be discussed below). It is notable that the mean yield of 30 l/min., which was established for 557 wells in the last part of project phase 1, largely exceeded the minimum requirement of 5-10 l/minute and showed a yield distribution displayed in Table 1. The maximum yields, though, which could have been safely taken from the wells, have not been determined and may be estimated as ranging, on the average, up to about twice the indicated yields.

For completeness, it must be clearly noted that the 691 mentioned drillings include all the control and test drillings. Of these, only 13 sites had been drilled, all in the area of Vavuniya Town and at the beginning of the project, and could be integrated with few exceptions into the new well system.

Furthermore, one has succeeded not only to place the majority of the well spots in the proximity of the locations desired by the population, but also to recognize very shallow lying fracture zones. The latter point allowed a reduction of the necessary drilling depths; the well depths essentially varied between 20 and 30 meters only, whereas other exploration companies resorted to drilling depths ranging up to 90 m in the same area or in comparable prospecting zones.

The value of this result has to be highly appreciated: in a terrain largely unknown from a hydrogeological point of view, proving to be particularly difficult on account of its principally crystalline bedrock of variable and mostly light fracture intensity, 654 wells have been successfully constructed within a short time and without any noteworthy precursory studies, partly under very difficult imposed conditions, and with a small staff and two relatively simple and medium-capacity rigs.

It remains to detail the remaining above-mentioned 53 drillings which, for three different reasons, could not be put into service:

Within the final evaluation of the entire program, only 27 of the 691 drillings can be considered as classical dry holes; that constitutes a failure rate of 4%. Not only for that particular area, a success rate of 96% must be considered as being untypically high; no prospecting area with comparable sub-soil conditions is known where such outstanding results have ever been attained. But before trying to make a reliable judgment about the question to what part the success, achieved in project phase 1, can be really attributed to the dowsing technique, one should pay attention to the information gained from various subsequently performed control tests and competing projects.

Comparison and Control Experiments

As has been conjectured by various parties before, a detailed analysis of the well documented facts concerning expenditure, planning, implementation and results of the first project phase, clearly showed the relevance of the applied technique. However, in view of the prejudices and comprehension difficulties related to the field of dowsing in general, it appeared necessary to present numerous and especially simple experiments in order to allow assessment and eventual confirmation on a broader basis. The three following tests point towards such a conclusion, for they have been purposely timed and yielded clear results, easy to evaluate.

Test 1: Successful Well Near Dry Drillings

Due to favorable circumstances, a significant test of the envisaged kind could be carried out very early in the first project area. If separately considered from a scientific point of view, the result can only be taken as a single and isolated case, but within the whole mosaic, it gets an appreciable practical value (a more precise repetition of that kind of experiment will be discussed in part 1.10). In a 200 x 200 meters school yard, two 90 m deep boreholes had been drilled into the crystalline rock basement by a project team financed by Norway—in both drillings no water was encountered at that depth. Geo-electrical soundings had not been carried out. On account of that situation, responsible persons from GTZ and the Bundesministerium für Wirtschaftliche Zusammenarbeit (BMZ: Federal Ministry for Economic Cooperation) asked Schröter to make use of his dowsing ability to solve the current problem and to locate a successful well as close as possible to the dry borehole drillings.

Schröter therefore examined the test area by means of dowsing. On the flat and restricted area almost out of vegetation an "intelligent guessing" of appropriate drilling points was visibly hopeless—as conceded by skeptical hydrologists—as no signs were present at the surface which could be exploited to reveal the presence of underground fracture zones (see part 3.1). According to this local situation, it clearly appeared to all participants that no success could be expected here by adherence to experience and conventional intuitions, often imputed to successful dowsers—and without introducing measuring techniques. After a short time, Schröter found, thanks to his subjective dowsing reaction, a place where he supposed that drinking water could be found at a depth of as low as 35 m and with a yield of at least 10 l/minute. The allegedly productive spot was located some 30 m from the one and 80 m from the other dry borehole.

A light mobile drilling rig could immediately carry out the test drilling and finished it by dawn of the same day. The result was unequivocal: water was found just as predicted. In this case, the value of the dowsing technique was confirmed, regarding not only the location but, to general surprise, also the depth and deliverable water quantity.

This clear-cut experiment contributed towards a more progressive attitude: GTZ and BMZ could no longer ignore this economical and successful method which promised a reduction of time and expenditure; it appeared no longer justified to stick exclusively to classical procedures because of principles and the lack of understanding the allegedly unconventional method applied by Schröter.

Test 2: Intentional Dry Borehole Drilling

At the end of the project phase 1, the cooperation between GTZ and the involved institutions of the University of Munich was put into effect; as one result of discussions with experts of earth sciences, GTZ was requested to carry out two different further experiments. The first one was to perform a dry borehole drilling, if possible near a successful well, the second one was to establish a direct and appropriate comparison between results obtained with conventional procedures and the dowsing technique.

Because of the prevailing imposed conditions and the rigorously controlled and appropriated financial allowance, it was of course impossible to proceed with intentional dry borehole drillings. Nevertheless, as an alternative it became possible to arrange for an exploration well very near a drilling which had been located by Schröter and produced more than 200 l/min. from a depth of 50 m. After intensive discussions, this test was put on the agenda and it was hoped to obtain both some information about the extension of the fracture zone and to complete the hydrogeological model representation for the area by means of quantitative data.

For that purpose, Schröter was requested to locate such a site by means of his dowsing technique, where he would expect a yield of less than 5 l/min. up to a comparable depth of 50 m, reaching into the bed rock. After having scoured the concerned area, Schröter thought that he had found an appropriate site 38 m from the said existing well. Of course, some water may be found within the surface layer of moderate thickness, at least for some time of the year, but that was not the issue. If that test succeeded, it could be shown once more by means of these two neighboring boreholes that the dowser exhibits special capabilities and that the relevant project area cannot be characterized by a homogeneous aquifer in the proximity of a successful drilling into the crystalline bedrock; instead, permeability is moderate and water may only be found in apparently small fracture zones. By the way, experienced dowsers claim to be able to differentiate water lying close to the surface (which is, thus, of less interest) from other water resources originating much deeper; evidently, the relevant biological sensations during dowsing are sufficiently different to allow for the required process of distinction and elimination.

According to Schröter's hypothesis—and in accordance with elementary geological evidence—such a distance could be viewed as being relatively large in a particular rock formation, so that it might determine success or failure of water detecti on. Unfortunately, the environment of the existing borehole had not been checked by geo-electrical techniques. From a conventional point of view, and without employment of sophisticated technical measurements, i.e. as long as sufficient information is not available about the presence of fractures, their extension and permeability, it can not be decided whether a site A or a site B which is 38 m distant from A would be more or less appropriate.

It should be stressed that according to the assessment of the participating experts, the selected test area did not, even after a thorough visual examination, allow good or bad drilling spots to be differentiated and pinpointed by intelligent observation or guessing within a radius of, say, 40 m.

The new drilling was carried out up to a depth of 50 m, similarly to the previous procedure. Between 9 and 11 m, i. e. within the superficial layer overlying the hard base rock, a relatively low yield of 13 l/min. was encountered—not unusual for the current season—but no measurable yield improvement could be detected while penetrating the underlying bedrock—there, the drilling was dry. By contrast, the neighboring successful well, fed by the crystalline zone, exhibits a yield of 237 l/minute at a depth of up to 50 m. Both wells, as well as their respective water tables have been thoroughly examined during the pump tests. No connection due to fractures could be noticed between the two wells. This result, typical for many areas, demonstrated that water may not be found anywhere in hard rock, because the expected groundwater accumulates mainly in narrow fractures and fracture systems. It is therefore necessary to attain a precise location of the drill sites; this seems to be possible by means of the method employed by Schröter and attributed to dowsing. Beyond doubt, these findings give more credibility to dowsing technique, provided that other remaining objections can be overcome (see the discussion in part 3.1).

Test 3: Systematic Comparison Experiment

No less significant is a directly arranged and controlled comparison between the two quite different procedures for ground water investigation, geophysics and the alleged dowsing technique, which has been carried out in order to provide a water supply for several small towns in Sri Lanka's Kurunegala District. At this instance, the objective consisted in the location of several wells with much higher yields of at least 100 l/min.

In a first step, a hydrogeologist and his collaborating expert team, already well familiarized with the successful project phase 1 and the local conditions, began to localize drilling points by the employment of modern hydrogeological and geophysical methods. Geo-electrical procedures played the most prominent part, as well as the use of geological maps and the study of aerial photographs. Besides this, the leading geologist, chairman of the Water Resources Board in Sri Lanka, had information at his disposal, which was not easily accessible and concerned former investigations within the relevant area in the Kurunegala District, especially on older wells not easily recognizable today. After several weeks of intensive work, 14 sites were located. Thereafter, Schröter was requested to inspect exactly the same area in order to determine drilling sites as well, but exclusively by means of the dowsing technique and without having any detailed knowledge of the available geological data. Within a few days, he could indicate 7 points. Then, the drilling of all 21 positions began, in all cases the same drilling team used the same drilling technique and the same criteria for the final depth (42–70 meters, dependent on the ground above sea level and the encountered underlying formations). The combined results are summarized in Table 2. Obviously, Schröter obtained the better scores.

The numbers of 14 and 7 locations involved are certainly not very impressive, but because of the very different results there is still a good basis for a practical evaluation. The appraisal of the success rate does not require a particularly sophisticated analysis. First, it must be stated that Schröter had, once more, successfully carried through his allotted task. Second, it was proved again, this time in a very well documented way, that the usual conventional siting method could not be applied with high success rates because of the particularly intricate underground conditions. Of course, one might claim, that the quality of the conventionally working team could be doubted; however, regarding the described conditions, it is rarely expected that other teams could have obtained a fourfold success (namely 80%).

TABLE 2
Conventional Technique Dowsing Technique
Number Liter/Minute Number Liter/Minute
1 400 * 1 400 *
2 400 * 2 200 *
3 300 * 3 188 *
4 80 4 150 *
5 60 5 150 *
6 45 6 150 *
7 25 7 30
8 22
9 17
10 10
11 7
12 6
13 1
14 1 * target quota reached

Table 2. Comparison between the yields of 21 exploration wells situated in the same area and located by means of conventional techniques (14; left column) and the dowsing procedure (7; right column). The required yield of 100 l/min. was reached, according to usual pump tests, in 3 of 14, and 6 of 7 cases, respectively. Altogether, with a success rate of 86% Schröter significantly surpassed the 21%-result obtained with the conventional method.

Finally, another experiment carried out in the same district of Sri Lanka is worth mentioning and will contribute to complete the insight. In one of the villages where the foregoing comparison test has been carried out, 4 drillings have been done at conventionally determined sites; two of them were practically dry and the two others provided insufficient yields with regard to the required water demand of the village. Due to organizational reasons, Schröter could not locate sites in this village during the former test. Because of the unsatisfactory results of these four drillings, Schröter was afterwards appointed here too in order to investigate the possibilities of the dowsing technique.

Thus, 4 sites could be located in and around this village by means of the dowsing technique at a later time; for two of them he expected particularly good yields exceeding 100 l/min. These additional 4 sites are not mentioned in Table 2 because they could not fulfill the agreed test conditions (drillings had already been carried out meanwhile and results were available). As predicted, the first good site determined by Schröter produced more than 200 l/min. and ensured the required water supply. The second "good" site is situated about 1 km away and has not yet been drilled. Each of the two remaining boreholes, however, produced only some 20 l/min.

Projects of Other Institutions

For different reasons, it was very difficult to establish an objective and fair comparison between the success rates of GTZ projects with the inclusion of dowsing techniques and various other water investigation projects in Sri Lanka. In spite of intensive efforts, it was not possible to get final reports from other organizations which had been active there. According to usual procedure, though, unsuccessful drillings would not have been particularly mentioned in such protocols. A possible comparison between the rates of success therefore must remain incomplete. Limited detailed data could only be obtained until now from two organizations, the Norway Cooperation Redd Barna [8] and a project supported by the World Bank [9] which will be mentioned in the following.

In 1980, two years before the beginning of the GTZ project, Redd Barna began the planning of deep wells (also to be functioning with hand pumps) for communities and villages in the Vavuniya, Mullaitivu and Mannar Districts. Concerning exploration area and purpose, far-reaching possibilities were given for comparison with the GTZ project to be carried through somewhat later. The Redd Barna project was supposed to be operational till 1989, but had already been interrupted in 1985 on account of the low success rate and the relatively high costs.

For a start, a simple drill rig (Hydra Drill) was used, by means of which 38 wells were drilled; from 1981 on, a more modern drill rig (Halco V493) came into operation. During the following 4 years 237 successful drillings were carried out. Nevertheless, only 154 of them were handed over in perfect working order. The report does not provide any details on the number of dry borehole drillings; the project manager, however, indicated by other means of communication a success rate of 50%, but the calculation basis is unknown.

The total average costs per well have been quoted by Redd Barna to amount to 77,000 Rs. Calculated on the same basis, the 654 wells built by GTZ within 3 years with 2 drill rigs (Velco Drill) of moderate capacity, were estimated to 25,000 Rs per well. The efficiency of Redd Barna therefore amounted to only 1/3 of the GTZ costs; this difference cannot only be explained by means of a different project organization (efficiency of the management). Besides that, Redd Barna and GTZ were both hindered by ethnical troubles in the project area. The argument that Redd Barna generally drilled deeper wells than GTZ cannot be considered as decisively important; drilling costs, on account of high supplementary costs, depend only partly on exact drilled depths. The indicated expenditures allow the preliminary conclusion that the success rate might have amounted to approximately 30%.

Incidentally, it might not be without interest to think about the reason for the differently chosen average depth of the wells in the two projects to be compared. In the GTZ program one succeeded in systematically locating those points where good wells could be established with a minimum of drilling. Apparently, Redd Barna had no such technique at its disposal and was urged, therefore, to rely on the supposedly increased chances associated with deeper drilling. The following paragraph is very informative, abstracted from the final report: "Some of Redd Barna's wells have been given up because in their immediate proximity the GTZ had established wells which provided a better water quality" (intended to state is also quantity). That is a clear statement and there is no hint that the situation has ever been reversed. On the contrary: the unusual success of GTZ did not remain unknown. Several of the other institutions, whose duty was also to supply drinking water, requested GTZ to support them with respect to well point location. In addition, it must be stated that Redd Barna repeatedly (and successfully) drilled on sites, previously located by Schröter, but which had not yet been taken over and carried out by his drilling team. The reality of these remarkable incidences is also reflected in Redd Barna's report. Limited information referring to a comparable project of the World Bank in Kurunegala District is also available (1982-85). It is reported therein that less than 30% of 848 drillings were successful [9].

 

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