Delineation of Ditches in Wetlands by Remote Sensing

Abstract: Wetlands have been heavily affected by human-alteration, this is done to drain thewetland so that the ground can be used for other purposes such as forestry oragriculture. With high accuracy data available now, it is possible to use differentmethods automatically to identify these ditches in wetlands or other areas. Fourdifferent methods were applied to two areas to delineate ditches. To compare the different methods, the results were quantified by comparing with amanually created map of the ditches. Drainage density and an agreement index wereused. The results indicate that the methods of impoundment index and map gullydepth are best able to distinguish the ditches in wetlands. The former gave a betterresult on areas inside wetlands while the latter gave a better result with non-wetlandareas. The other two methods make mistakes and misjudgements that givemisleading results, they ignore ditches partially or completely, or finds ditches inareas without them. Even so, all methods are at least a clear improvement over thecurrently available property map's water flows, but not in the same class as the timeconsumingmanual method.