A New Algorithm for Delineation of Surface Depressions and Channels

Ning Wang,Xuefeng Chu

doi:10.3390/w12010007

Abstract

Topographic delineation is critical to watershed hydrologic modeling, which may significantly influence the accuracy of model simulations. In most traditional delineation methods, however, surface depressions are fully filled and hence, watershed-scale hydrologic modeling is based on depression-less topography. In reality, dynamic filling and spilling of depressions affect hydrologic connectivity and surface runoff processes, especially in depression-dominated areas. Thus, accounting for the internal hydrologic connectivity within a watershed is crucial to such hydrologic simulations. The objective of this study was to improve watershed delineation to further reveal such complex hydrologic connectivity. To achieve this objective, a new algorithm, HUD-DC, was developed for delineation of hydrologic units (HUs) associated with depressions and channels. Unlike the traditional delineation methods, HUD-DC considers both filled and unfilled conditions to identify depressions and their overflow thresholds, as well as all channels. Furthermore, HUs, which include puddle-based units and channel-based units, were identified based on depressions and channels and the detailed connectivity between the HUs was determined. A watershed in North Dakota was selected for testing HUD-DC, and Arc Hydro was also utilized to compare with HUD-DC in depression-oriented delineation. The results highlight the significance of depressions and the complexity of hydrologic connectivity. In addition, HUD-DC was utilized to evaluate the variations in topographic characteristics under different filling conditions, which provided helpful guidance for the identification of filling thresholds to effectively remove artifacts in digital elevation models.

Highlights

Surface depressions are one of the dominant topographic characteristics for many landscapes.For example, the Prairie Pothole Region (PPR) in North America is unique due to its numerous depressions
HUD-DC implements ArcGIS-based surface delineation to reveal the hydrologic connectivity at a watershed scale by identifying a series of hydrologic units (HUs), including puddle-based units (PBUs) and channel-based units (CBUs), and provides topographic information related to depressions and channels for hydrologic modeling in depression-dominated watersheds
To test the performance of HUD-DC in surface delineation, it was applied to the Upper Pipestem

Summary

Introduction

Surface depressions are one of the dominant topographic characteristics for many landscapes.For example, the Prairie Pothole Region (PPR) in North America is unique due to its numerous depressions. It can be a challenge to model hydrologic processes in such depression-dominated areas [1,2]. As a pre-processing procedure of hydrologic modeling, surface delineation is essential and critical to reveal hydrologic connectivity across a land surface. Depressions in a watershed (including artifact depressions) are commonly removed by implementing filling and/or breaching approaches [3,8,9,10,11,12,13,14]. It is assumed in these methods that the entire watershed contributes surface runoff to its associated outlet. This assumption can be appropriate for watersheds with fewer depressions, but not for depression-dominated areas like PPR

Objectives

Methods

Results

Conclusion