Impact of power line construction upon the hydrology of part of a mid-latitude swamp

A study was carried out to determine the hydrologic impact caused by the construction of a power transmission line across a swamp in southern Ontario, Canada. The creation of forest openings for the erection of towers led to local increases in rainfall and snowfall reaching the ground. Spatial variation in snow distribution was also caused by differential heating of the snow-pack in the openings. During the construction period, such activites as drilling and pumping caused irregularities in the ground water level regimes.Recovery from the construction effects was rapid. Thus, lateral ground water flow and recurrent flooding quickly eliminated water level anomalies. At the construction sites, the continued absence of a forest cover will have more effects on precipitation distribution. However, in view of the limited areal extent of the disturbed areas, the hydrology of the swamp as a whole will not noticeably be altered.