ASSESSMENT OF HAND-HELD GPS SURVEYING IN LAND ADJUDICATION: A CASE STUDY OF NGOLIBA SETTLEMENT SCHEME IN KENYA
Keywords:land adjudication, hand-held GPS, total station, aerial photograph, PIDs, Ngoliba
Land adjudication is the process through which existing rights in a particular parcel of land are ascertained. Land ownership in Kenya is largely achieved through a land adjudication process, especially in the rural areas. The Preliminary Index Diagrams (PIDs) are the official map documents that together with adjudication records constitute the adjudication register required for determination and registration of interests and rights over land. The PIDs are produced from enlarged, marked and un-rectified aerial photographs; hence they contain distortions. This paper assesses the application of hand-held GPS surveying to determine plot boundaries in an adjudication area in Kenya. The study was conducted in Ngoliba Settlement schemes. Areas of 12 plots of similar sizes were obtained by three methods - PIDs, traditional ground based surveying using a station-theodolite and EDM (total station) and using a hand-held single GPS (in point positioning mode). Plot areas obtained from PIDs and GPS were compared against those determined from total station measurements, which are taken as the standard in this study. We also compared the coordinates and side lengths derived from total station and handheld GPS measurements. Results show that hand-held GPS can recover 98.1% of the combined area of the 12 plots compared to PIDs which can only recover 77.5%. Results from coordinates and side lengths differences show that hand-held GPS can determine side lengths and coordinates that are approximately close to the ones obtained by total station. Hence Hand-held GPS would significantly improve the accuracy of parcel areas for land adjudication when compared to those obtained from PIDs only.