Flow map

The flow map shows the lines in the landscape where the water is potentially concentrated after a rainbui, taking into account topography and existing watercourses. A distinction shall be made between the single-line flow map and the multiple streamlining flow-map. In the case of the single-line flow-chart, the calculation algorithm shall direct all the run-off water due in a pixel to the lowest surrounding pixel (Single Flow Direction). This creates concentrated, clearly aligned run-off lines that represent the sites in the landscape with the highest probability of run-off. When using multiple lines, the calculation algorithm leads all the flowing water to a pixel proportionally to all the lower surrounding pixels, with the lowest pixel receiving the most flow and the least lower pixel receiving the least flow (Multiple Flow Direction). This creates diffuse flow lines that give a more realistic picture of slope flow.本流量图（flow map）展示了在考虑地形与现存水系的前提下，降雨后景观中潜在的水体富集线条。需对单线流量图与多流线流量图加以区分。针对单线流量图，其计算算法会将单个像素（Pixel）内产生的全部径流，导向周边地势最低的像素（单流向算法（Single Flow Direction））。由此生成的径流线条集中且排布规整，代表了景观中径流发生概率最高的区域。当采用多流线模式时，计算算法会将所有流水按比例分配至周边所有地势更低的像素，其中地势最低的像素承接最多流量，地势最低程度最弱的像素承接最少流量（多流向算法（Multiple Flow Direction））。由此生成的径流线条较为弥散，更能真实反映坡面径流的实际形态。