Driss Ennaanay, Stacie Wolny, Guillermo Mendoza, Heather Tallis, Kannan

Narayanan, and Jeff Arnold.

ForACES – Naples, Fl- Dec 8-11, 2008

Introduction

Land Use Impacts on Water Resources

InVEST Water Models

Focus on Water YieldPhilosophyResultsComparison to SWATClimate Change

May 4 – 17

Areas of annual row cropping

April 20 – May 3

Areas of perennial vegetation

Evaluation of how landscape management impacts water resources,In the context of:

- Complexity and site-specificity of the natural conditions and climate regimes

- Data availability- Complex to model

Land Use impacts Hydrology: Water Yield: Seasonality and QuantityFlooding: Timing and Peaks (stormflow)Baseflow: Magnitude and TimingWater Quality: Loads and TimingErosion: QuantityErosion/Flow: flow frequency and sediment loading frequency

Any changes in land use will change hydrologic regime.

Any changes in terrestrial ecosystems and landscape processes will change Hydrologic services such as provisioning of water supply (irrigation and hydropower) and regulation of water quality

InVEST tools are used to compare land use scenarios and investigate impacts on hydrologic regime.

Need to understand linkages fairly quickly

Simple and generalizable

Key / basic ecosystem processes

Data must be readily available Minimal data neededRelative values w/ physical units

Relative Scoring: Comparing landscape within basin

Prioritize management activities under poor data conditions

Planning and Targeting monitoring and research

Engage Stakeholders.

Logic/Service/Model

Water Yield

Water Retention

Erosion/ Sediment Retention

Storm Peak

Water Quality

PRINCIPLE Water Balance

Topo_ind. Soil-Water-Storage

USLE SCS-CN Export Coef. (EPA)

Hydropower-Reservoir

X X

Hydropower-Run-of-River

X X

Irrigation X

Storm Peak Mitigation

X

Pollutant Regulation

X

http://invest.ecoinformatics.org

Model: Yield = Precip. – f(ETo)Yield is defined as the volume of water that DOES NOT evapo-transpire.Water that is potentially available but don’t know where it is* Might be storm runoff* Might be baseflow* Some might go to deep groundwater only accessible by a deep well, or by farmers 1000s of miles away, in a 1000 years time

Applying General Hydrologic LawWe can state something without detailed calibratingNo Temporal Dynamics: Annual AverageLeaf dynamics and physionomy (sp?) are not importantNo cell/pixel Interconnectivity each cell is directly connected to the stream (like most models!)Fog Drip not consideredSnow is ok if converted to Snow Water Equivalent.

RastersAnnual PrecipitationReference Evapotranspiration (ETo)Soil DepthPlant available water content

Table FieldsEvapotranspiration coefficientRoot Depth

Sub-Watershed

sWater Yield

Eco-region R2Kendall Tau (τ) p-value

Willamette111

nl 0.38 < 0.01

Texas122

0.89 0.59 < 0.01

Tennessee32

0.96 0.89 < 0.01

Lower Co.85

nl 0.59 < 0.01

California135

0.95 0.42 < 0.01