Flow Direction Overview

Introduction

It is very important to know the flow directions in the facility network analysis. Before the analysis, you need to ensure that the network data have the flow direction field, and specify the field as the Flow Direction Field in the Environment Settings window. The flow direction is determined by two factors: network connectivity; locations of the sources and sinks. Source belongs to the junction feature, which makes the substance flows away from it through the network edges. Take for example the irrigation system, the pumping stations can be abstracted as the sources, because the water within the pipeline is always flowing away from the pumping stations. The sink is also the junction feature, which make the substance flows into it through the edges. Take for example the river system, the estuary can be abstracted as a sink, because the water is always flowing into it. The stream flows out of the source, and finally flows into the sink.

The flow direction can be created by the source or sink, so generally you just need to specify the source and sink in the network. According to the locations of the sources and sinks, the source-sink field information will be saved into the attribute table of the point dataset. The source-sink field has 3 types: 0 denotes the common node, 1 denotes the source node, and 2 denotes the sink node.

SuperMap provides the function to build the flow direction in the network analysis module. The flow direction information will be saved into the flow direction field after it is built. The default name is Direction. Please see Tracking Analysis Network Modeling for how to build the flow direction.

When creating the flow direction, you firstly need to specify the source and sink in the tracing network, and then save the information of the source and sink into a field. The flow direction is calculated with the source-sink field. In addition, you also can create the grade field for saving the grade information of different networks.