Comparison of drainage density in sapping valleys and runoff valleys on the western half of Molokai, Hawaii, USA

Rapach Lagowski, Maddy

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https://hdl.handle.net/2142/129020 Copy

Description

Title

Comparison of drainage density in sapping valleys and runoff valleys on the western half of Molokai, Hawaii, USA

Author(s)

Rapach Lagowski, Maddy

Issue Date

2025-08-13

Keyword(s)

• geomorphology
• GIS
• drainage density

Date of Ingest

2026-04-17T16:08:58-05:00

Geographic Coverage

Molokai, Hawaii, USA

Abstract

Drainage density is calculated as the ratio of total stream length to the total area of a drainage basin (Schumm, 2013). This property reflects the characteristics of a landscape, including evolutionary journey, lithology, and climate (Schumm, 2013, Sangireddy et al., 2016). When drainage density is known, we can predict flood peaks, sediment yields, erosion and mean annual discharge. However, due to the myriad of variables, and intersection of such variables, that affect formation of channels and catchments, drainage density can be difficult to predict (Schumm, 2013). Factors that can influence drainage density include vegetation, lithology, mean annual precipitation, precipitation intensity, slope, soil texture, human activity, and stage of drainage-network development (Schumm, 2013, Sangireddy et al., 2016). We seek to isolate one influencing factor to determine its relationship with drainage density in a specific location, with limited confounding variables. Traditional techniques for remotely measuring drainage density, which include using coarse, 10 meter or 30 meter digital elevation models (DEM) as well as a channel initiation threshold to extract stream data, can introduce errors and inaccuracies (Sangireddy et al., 2016, Clubb et al., 2014). The use of high resolution LiDAR data allows for a more detailed analysis of topography and more precise channel extraction. Additionally, modern methods of remote channel extraction avoid the use of a channel initiation threshold and instead determine a stream’s presence based on the shape or characteristics of the topography. Studies have found these modern methods produce more accurate delineations of channels and catchments (Clubb et al., 2014). Therefore, we use LiDAR data with modern methods of channel extraction to ensure a highly precise analysis. The defining feature of the eastern half of the Hawaiian island of Molokai is a volcano which has contributed to the formation of two classifications of valleys: sapping valleys and runoff valleys. These valleys are different from one another in channel formation, hydrology, and topographical characteristics. Furthermore, studies have shown that drainage density is lower in sapping valleys than runoff valleys on the eastern half of Molokai (Kochel & Piper, 1986). However, minimal research has been conducted regarding the relationship between drainage density and valley classifications on the western half of Molokai. In response to this data gap, we propose a study to determine if there is a statistically significant difference between drainage density in sapping valleys and in runoff valleys on the western half of Molokai which will use LiDAR data and modern channel extraction methods.

Type of Resource

text

Genre of Resource

technical report

Language

eng

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