How wide is a wetland boundary?

Abstract

New South Wales State Environmental Planning Policy 14 – Coastal Wetlands (SEPP 14), which was introduced in 1985, is accompanied by a series of 1:25000 maps which delineate coastal wetlands for the purposes of controlling development. The wetlands were mapped by interpretation of botanical indicators using colour aerial photography at an approximate scale of 1:25000 (Adat et al, 1985). For this scale of map the actual boundary line of the wetland areas is 10 to 20 metres wide,a feature which invoked immediate criticism. This criticism was countered in an amendment to SEPP 14 which stated that the outside edge of the boundary line was the edge of the wetland. Nevertheless, the scale of mapping still led to difficulty in accurately transcribing the wetland boundary to a larger scale map. In addition, many errors have been found in comparing SEPP 14 boundaries to the actual extent of wetlands on the ground (Winning, 1991; Payne & H\arty, 1998). In order to more accurately define the extent of wetlands, some Councils are developers have undertaken ground surveys of wetland boundaries. The techniques used have generally involved the delineation of a boundary by a wetland specialist interpreting vegetation or some other feature, with that boundary being subsequently plotted on a map of appropriate scale using various surveying techniques (Winning,1991; Payne & Harty,1998). This results in a sharp line which is then used to delineate the wetland’s edge for planning and legal purposes.