hydrology

Introduction to Wetland Water Budgets

• Importance of understanding water inflow and outflow in wetlands.

• Comparison of wetland budgeting to personal finance - tracking what's coming in and going out.

• Focus on the significance of water sources and quality in wetland health and conservation.

Water Inputs to Wetlands

• Precipitation:

  • Major input through rainfall and snowfall.

  • Can be intercepted by vegetation, affecting what reaches the wetland.

  • "Through fall" refers to precipitation that makes it through the canopy to the ground.

  • Surface inflow: Water flowing into wetlands from surface sources with specific water quality characteristics.

  • Groundwater inflow: Water seepage from surrounding areas into the wetland.

  • Tides and Seiches:

    • Seiche: A standing wave in an enclosed or semi-enclosed body of water (like Lake Erie) influenced by wind.

    • Tides can both introduce and remove water from wetlands, affecting water levels.

Water Outputs from Wetlands

• Evapotranspiration (ET):

  • Combination of evaporation from free water surfaces and transpiration from plants.

  • Important metric for evaluating wetland water loss.

• Groundwater outflow: Water leaving the wetland and returning to the groundwater system.

• Surface outflow: Water that drains from the wetland surface into adjacent water bodies.

Analyzing Wetland Budgets

• Importance of analyzing how water volume changes over time, calculated as:

  • $ext{Change in Volume} = rac{ ext{Delta V}}{ ext{Delta t}}$

    • Necessary for assessing health and function of a wetland.

• Variability of water sources is characteristic to wetland types affecting management practices.

Surface Flow Measurement

• Critical in assessing how much water is flowing into or out of wetlands.

• Measurement techniques:

  • Heavy reliance on the velocity of water and cross-sectional area of flow.

  • $ext{Flow} = ext{Velocity} imes ext{Cross-Sectional Area}$

• Stream gauges are commonly used for long-term measurement of water levels and flows.

Estimation Methods

• Manning Equation: Used for estimating surface flow velocity in channelized areas based on channel characteristics.

  • Variables include cross-sectional area, hydraulic radius, and the Manning coefficient.

• Importance of site-specific measurements and adjustments based on sediment type (rock, gravel, vegetative matter).

Groundwater Interactions in Wetlands

• Distinction between Recharge and Discharge Wetlands:

  • Recharge wetlands: Water is added to groundwater systems.

  • Discharge wetlands: Water is released from groundwater to the wetland.

• Darcy's Law: Governs the flow through groundwater systems, incorporating hydraulic conductivity, cross-sectional area, and gradient.

Transpiration Dynamics

• Transpiration is the primary way water is transferred from soils through plants into atmosphere.

• Influence of plant growth and seasonality on evapotranspiration rates, affecting water availability in wetlands.

Seasonal Tidal Variability

• Tidal influence varies significantly depending on location, typically described as Diurnal (one high/low tide) or Semidiurnal (two high/low tides) patterns.

• Seasonality can significantly affect average sea levels and subsequent wetland flooding patterns over time.

Monitoring Techniques

• Suggestions for various tools and methods for monitoring wetland hydrology:

  • Use of weirs, evaporation pans, and through fall monitors for quantifying precipitation and evaporation.

  • Employing sophisticated hydrological models and empirical studies for effective wetland management.

Conclusion and Summary

• Revisiting the health of a wetland is essential for biodiversity, ecosystem services, and local watershed management.

• A comprehensive understanding of wetland budgeting principles is vital for effective conservation practices and ecological study.

Questions

• Open floor for any final questions on presented material.

• Encouragement that future classes will cover different and possibly less complex topics.