Teaching the Hydrologic and Geomorphic Significance of Drainage Basins and Discharge in Physical Geography

Abstract

Drainage basins, stream discharge, and sediment discharge are fundamental concepts in physical geography, and they play an integral part in other cognate disciplines. To enhance student understanding of water and sediment discharge there needs to be an integration of field-based monitoring exercises with classroom exercises using readily available (published) discharge data from water resource agencies. This paper outlines two groups of exercises. The first set of exercises involves a combination of field-based monitoring and associated laboratory analysis, and they include the following worked examples for Manoa Stream, Oahu, Hawai'i: 1) discharge measurement using the velocity-area technique, 2) measurement of suspended sediment concentration, and computation of suspended sediment load, yield and erosion rates for a drainage basin, and 3) determination of channel hydraulic parameters.

The second set of exercises was developed for students who are not able to conduct field monitoring. These may also be used by students who have completed field discharge monitoring. These exercises focus on readily available daily discharge data for several drainage basins in Hawai'i, and worked examples include: 1) developing annual stream discharge hydrographs for drainage basins of different size, 2) comparing river regimes of local systems to global models, and 3) developing flow-duration curves for different drainage basins.

Utilization of real-world discharge data allows students the opportunity to explore relationships and to grasp the underlying controls on discharge variation from drainage basins. These are important aspects in developing an understanding of water and sediment linkages within environmental systems.

Key Words:

• discharge
• suspended sediment
• channel hydraulics
• physical geography
• river regime
• hydrograph
• flow duration curves