Archaeological Applications of Low-Cost Integrated Sidescan Sonar/Single-Beam Echosounder Systems in Irish Inland Waterways

Inland waterways, such as rivers and lakes have been foci of human settlement and use for millennia. However, underwater archaeological prospection or survey in these environments is often hindered by poor or no-visibility conditions. While this can be overcome using a range of well-established geophysical techniques, their application in inland waterways seems comparatively less common than in offshore environments. Possible reasons include the logistical challenges of surveying shallow confined, often inaccessible and uncharted waters coupled with a wider lack of awareness of the submerged archaeological potential of inland waterways. This paper demonstrates one method by which the logistical challenge can be circumvented, specifically the use of low-cost acoustic systems which combine a single-beam echo sounder and sidescan sonar. These systems have appeared within the last decade and are smaller and cheaper than their survey-grade counterparts. Although developed for the sport fishing community, as shown here, they can also be used for archaeological purposes. Their effectiveness for archaeological prospection is illustrated via three case studies from lacustrine and riverine settings in Northern Ireland and by reference to object detection and bathymetric mapping. The data presented indicate that the low-cost systems are capable of collecting data that is sufficient for archaeological purposes but they are best suited to shallow confined waters where their disadvantages (limited range and depth of operation, reduced image quality) are minimized. Copyright (c) 2016 John Wiley & Sons, Ltd.