Ecosystem Restoration Flashcards

Which design approach uses natural channel geometry derived from stable reference reaches rather than solely relying on hydraulic equations?

Answer: Natural channel design (Rosgen methodology)

Natural channel design uses dimensionless ratios from stable reference reaches to set width, depth, slope, and pattern, providing geomorphically appropriate geometry.

A restored prairie pothole shows declining water levels across multiple dry years. What hydrologic monitoring approach best distinguishes climate variability from drainage infrastructure failure?

Answer: Paired monitoring of wetland stage and regional precipitation/ET with drainage tile inspection

Pairing wetland stage data with precipitation and ET records isolates climate forcing, while tile inspection detects subsurface drainage that can override restoration.

In riparian restoration, what is the primary hydrologic role of established native vegetation along stream banks?

Answer: Stabilizing banks through root reinforcement, reducing erosion, and increasing evapotranspiration

Riparian roots mechanically reinforce banks, leaf litter increases infiltration, and ET returns water to the atmosphere, collectively stabilizing the hydrologic regime.

What metric defines the 'entrenchment ratio' in Rosgen stream classification, and what restoration implication does a low value carry?

Answer: Flood-prone width divided by bankfull width; low value means the channel is entrenched and disconnected from its floodplain

Entrenchment ratio = flood-prone width / bankfull width; values <1.4 indicate a highly entrenched channel with limited floodplain access, requiring grade control or valley reconstruction.

Which abiotic factor most strongly controls the rate of sediment accumulation in a restored mangrove system?

Answer: Tidal range and suspended sediment concentration in tidal water

Tidal range determines inundation frequency and duration, while suspended sediment concentration in tidal water governs how much material is available to settle between tides.

A hydrographer is designing a step-pool sequence to reduce stream power in a steep restoration reach. What is the functional purpose of this structure?

Answer: Dissipating excess stream energy and preventing bed incision on steep gradients

Step-pool sequences convert kinetic energy to turbulence at each step, reducing unit stream power and stabilizing steep channels against incision.

When evaluating restoration success using the 'trajectory approach,' what does a positive trajectory indicate?

Answer: The ecosystem attributes are moving consistently toward reference condition over time

A positive trajectory means measured attributes are progressively converging toward reference conditions, confirming the restoration is on the right path even if not yet complete.