Identifying and Calibrating a Catchment Area - In this lesson, you will learn how to delineate a catchment area using topographic maps. Start by visualizing the landscape, where contour lines represent elevation, and water flows perpendicular to these lines. To define a catchment area, trace the high points (ridges or hilltops) surrounding a stream or wetland. By drawing lines perpendicular to the contours, you’ll mark the boundaries of the catchment, which is the entire drainage area that contributes water to the wetland or stream. This process helps identify areas affecting water quality and runoff, making it essential for environmental assessments.