Informing Evapo-Transpirative Cover Design With Plant Water Use Efficiency

Transcription

1 Informing Evapo-Transpirative Cover Design With Plant Water Use Efficiency Mr. Robert Murphy Certified Professional Soil Scientist Mr. Jesse Dillon Senior Reclamation Ecologist, Principal Acknowledgement to Dr. Ed Redente Prof. Emeritus - CSU Cedar Creek Associates, Inc

2 Presentation Overview Evapo-Transpirative (ET) Cover Theory Transpiration (T) Leaf Area Index (LAI) Water Use Efficiency (WUE) Application to TSF, northern NV Other Applications of WUE

3 Review of ET Covers Cover Buried / Encapsulated Materials Soil / Alluvium Tailings PAG Waste Rock Radioactive Materials

4 Goal of this Presentation Get a better handle on Transpiration / LAI Apply in useful ways (WUE)

5 Transpiration Difficult to quantify Varies annually Temperature (elevation, latitude) Precipitation (amount, timing) Varies seasonally Northern NV LAI Transpiration Peak Veg Production AZ / NM Jan Feb Mar April May June July Aug Sept Oct Nov Dec

6 Transpiration / LAI LAI *Deserts ( ) *Grasslands ( ) *Shrublands ( ) Pixel Classification Technique to Measure LAI

7 Leaf Area Index LAI Biomass = Transpiration April July Sept

8 Leaf Area Index Biomass Transpiration

9 Leaf Area Index LAI Time Grasslands Mixed Grass - Shrub Sagebrush 0-5 Years 5-15 Years Years

10 Biomass Allocation Where LAI Meets WUE 50% 33% 25% Ground Surface 50% 66% 75% 3 FT Depth Cover Waste / Tailings

11 Water Use Efficiency WUE = volume of water required for plant species to produce one unit of biomass. (X ml H2O = X g Plant Biomass) *Data Available for Common Reclamation Species

12 Water Use Efficiency Cheatgrass (Bromus tectorum) Big Sagebrush (Artemisia tridentata)

13 Water Use Efficiency

14 Water Use Efficiency Thunder Basin Nat l Grassland, Wyoming Kobeh Valley, Eureka County, NV

15 Water Use Efficiency Big Sagebrush WUE 2,216 ml/g Pernennial Grass 1,000 ml/g Annual Grass 280 ml/g

16 Water Use Efficiency Big Sagebrush Pernennial Grass WUE 2,216 ml/g 1,000 ml/g 2x Annual Grass 280 ml/g

17 Water Use Efficiency WUE Big Sagebrush 2,216 ml/g Pernennial Grass 1,000 ml/g 2x 8x Annual Grass 280 ml/g

18 Water Use Efficiency TSF Northern NV Project Goals Sustainable vegetation community (transpiration) Sufficient plant cover to limit erosion Constraints Volume of available cover materials Likely thin cover (12-18 inches) Our Primary Objective What vegetation community do we expect? How much water required to sustain vegetation?

19 Water Use Efficiency TSF Northern NV Project Goals Sustainable vegetation community (transpiration) Sufficient plant cover to limit erosion Constraints Volume of available cover materials Likely thin cover (12-18 inches) Our Primary Objective What vegetation community do we expect? How much water required to sustain vegetation?

20 Water Use Efficiency TSF Northern NV Project Goals Sustainable vegetation community (transpiration) Sufficient plant cover to limit erosion Constraints Volume of available cover materials Likely thin cover (12-18 inches) Our Primary Objective What vegetation community do we expect? How much water required to sustain vegetation?

21 Water Use Efficiency TSF Northern NV Modeled Transpiration in Avg Year = 4.62 inches (474,705 L H2O/Acre) Composition Plant Production WUE Total Total (milliliter:gram) grams / acre pounds / acre Perennial Grasses Perennial Forbs Shrubs Big Sagebrush Fourwing Saltbush 50% 1, , % , % 2,216 42, % , Annuals 7% , Total Plant Production NRCS Lower Estimate = 366 lbs / Acre Current Annual Growth 359

22 Water Use Efficiency TSF Northern NV Discussion - Could we have done better? Soil Development (Pedogenesis) 0 ft Aw A (Low Density, Sandy) Btw Bt (Increase in Clay) Mixed Media C Bk (Increase in carbonates) C (Bulk material) 3 ft 0 years 2-10 years 10+ years

23 Water Use Efficiency TSF Northern NV Vegetation Considerations 1. Fluctuations in Transpiration 1. Increased in wet years 2. Decreased in dry years

24 Water Use Efficiency TSF Northern NV Vegetation Considerations 1. Fluctuations in LAI 2. Sustainability Threshold 1. There is a limit to plant stress 2. Goals may not be met

25 Water Use Efficiency TSF Northern NV Vegetation Considerations 1. Fluctuations in LAI 2. Sustainability Threshold 3. Realistic Vegetation Composition 1. Site specific revegetation surveys 2. Adjusted for anthropogenic soil system

26 Future Studies Cover Depth Optimization Moving earth is $,$$$,$$$.$$

27 Future Studies Cover Depth Optimization Designed Vegetation Communities Site specific seed mixes Optimized to timing, rate, duration, distribution

28 Future Studies Cover Depth Optimization Designed Vegetation Communities Evaporation vs. Transpiration Deciphering Completed projects With or without lysimeters

29 Finding Data to Apply WUE Site Field Surveys Ask site environmental staff for data.

30 Finding Data to Apply WUE Site Field Surveys Baseline Data NEPA permitting documents vegetation surveys Ecological site / soil verifications Reclamation Plan (MPO)

31 Summary Main Takeaways LAI is Extremely Variable Ranges from 0.85 to 5.48 in arid systems LAI / Transpiration Relationship is Imperfect WUE helps evaluate accuracy of LAI and T

32 Thanks for your time! Questions?