ABSTRACT
ABSTRACT The drainage pattern of a river network is the arrangement in which a stream erodes the channels of its network of tributaries. It can reflect the geographical characteristics of a river network to a certain extent because it depends on the topography and geology of the land. Whether in cartography or geographic information system (GIS), hydrography is one of the
CONTENTS
8.1 Introduction ................................................................................................ 120 8.2 Fundamentals of Fuzzy Logic .................................................................. 122
8.2.1 Fuzzy Set ......................................................................................... 122 8.2.2 Fuzzy Operator .............................................................................. 123 8.2.3 Fuzzy Rule ...................................................................................... 123
8.3 Evaluation Methods ................................................................................... 124 8.3.1 Predicates and Fuzzy Rules ......................................................... 124 8.3.2 Evaluation Method for Each Pattern ........................................... 126
8.3.2.1 Dendritic Pattern ............................................................. 126 8.3.2.2 Parallel Pattern ................................................................ 126 8.3.2.3 Trellis Pattern ................................................................... 126
8.4 Experiments and Results .......................................................................... 127 8.4.1 Experiment Design ........................................................................ 127
8.4.1.1 Strategies to Be Tested .................................................... 127 8.4.1.2 Testing Data ..................................................................... 128
8.4.2 Case Studies in Russian River ...................................................... 129 8.5 Conclusions ................................................................................................. 132 References ............................................................................................................. 132
most important feature classes to generalize in order to produce representations at various levels of detail. Cartographic generalization is an intricate process whereby information is selected and represented on a map at a certain scale not necessarily preserving all geographical or other cartographic details. There are many methods for river network generalization, but the generalized results are always inspected by expert cartographers visually. This chapter proposes a method that evaluates the quality of a river network generalization by assessing if drainage patterns are preserved. This method provides a quantitative value that estimates the membership of a river network in different drainage patterns. A set of geometric indicators describing each pattern are presented, and the membership of a network is defined based on fuzzy logic. For each pattern, the fuzzy set membership is given by a defined IF-THEN rule composed of several indicators and logical operators. Assessing the quality of a generalization is done by comparing and analyzing the values before and after the network generalization. This assessment method is tested with several river network generalization methods on different sets of networks, and results are analyzed and discussed.
