Introduction

Since its inception, the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) has supported, at the request of the German Government, appropriate measures for water supply improvement in many countries. Although this activity represents only of a small sector of GTZ's numerous projects, a particular significance has been allocated to it. The availability of sufficient and high-quality drinking water is a basic human requirement; that is why numerous world-wide organized efforts are being pursued within this sector. In addition, it must be kept in mind that polluted water actually causes some 80% of all the diseases in the Third World. As a consequence, it can be anticipated that the already inadequate supplies for at least 2 billion people will become even more problematical in the near future.For a significant number of countries, mainly in the Third World, the supply conditions deteriorated markedly in the past years. This was mainly due to the population growth in urban areas — which continues to proceed too fast and far too extensively -- the increasing per-capita water consumption and the shortage or depletion of appropriate resources available for the water supply. Moreover, the extension of regional arid areas must be taken into account, partly the consequence of inappropriate or incorrect soil management, such as large scale deforestation, or climatic changes resulting from a number of complex chain reactions, partly induced by mankind.

These described conditions show very clearly that it is urgent to exploit the natural available water resources more intensively and more efficiently. In particular, techniques should be improved in their efficiency which aim at the investigation of still unknown subterranean water reserves. This is relevant, to a high degree, for thinly populated areas where a great number of wells are lacking — although delivery of relatively low yields is mostly sufficient here. Altogether it is true that modern techniques offer a rich choice of prospecting methods, but applications cannot be pursued to the desired extent because in most cases they turn out to be too time-consuming and too costly, and are often inadequate to guarantee a high rate of success. Experiences with classic methods has shown that, particularly in moderately fractured crystalline rock basement, the rate of dry drillings must be considered as being relatively high. It is therefore advisable to examine all available techniques with respect to their potential to allow an increase of the success rates for identifying proper well sites.

In 1986, GTZ presented in its series of publications a special report number 183 on a project in the northern dry zone districts of Sri Lanka, where dowsing techniques have been implemented on a large scale for the identification of well sites [1]. The resulting success and the economic benefit turned out to be unexpectedly high, thus justifying this unconventional technique despite all initial doubts and reservations, put forward from various parties.