Nutrient and Sediment Modeling of the Yahara Lakes Watershed

Transcription

1 Nutrient and Sediment Modeling of the Yahara Lakes Watershed Yahara CLEAN Project Rob Montgomery John Panuska

2 Watershed Remediation Flow Chart - Watershed-scale Analysis - Pheasant Branch Field-scale pilot project Watershed Scale analysis - SWAT Field-scale analysis SNAP Plus Relative ranking of sub-areas Implement management practices Evaluate lake water quality Goal met Goal not met

3 Topic Overview Watershed model input data Results of watershed scale modeling The field scale modeling approach Implementation to meet watershed goals

4 Watershed Model Input Data Topographic, soils, land use Climate Livestock and manure spreading Stream gage data on runoff and nutrients

5 Building the Watershed Model Define watersheds Assemble and check data Define modeling process Calibrate model to stream gage data

6 Existing Land Use Sediment Delivery Variable by location Related to land use, soils, topography All areas contribute sediment

7 Manure Analysis Where & How Much? Manure application rates based on: Number of animal units Haul distances Agricultural land available for spreading

8 Existing Land Use Phosphorus Delivery Extremely variable by location Dependent on soils, manure application, tillage practices Highest loadings to Mendota, but also substantial loadings to Waubesa and Kegonsa

9 Phosphorus Contribution by Watershed 70% 60% 50% 40% 30% 20% 10% Phosphorus Contribution to the Yahara Chain of Lakes 0% Mendota Monona Waubesa Kegonsa

10 Nutrient Delivery Under Alternative Land Use Scenarios 1. Continuation of existing land-use patterns 2. Increases or decreases in manure application 3. Planting the watershed to continuous perennial crop

11 Phosphorous Load Reduction Across Watershed Existing Land Use Manure Control Manure Control & Perennial Crops

12 Nutrient Reduction by Land Management Scenario - Lake Mendota Watershed - Land Management Change Estimated Total Reduction in P 100% Manure Control ~ % 80% Manure Reduction ~ % 60% Manure Reduction ~ % 25% Manure Increase ~ % No Manure & Perennial Crops ~ % Urban TSS Reduction ~ < 5 %

13 Nutrient Reduction by Land Management Scenario - Lake Monona Watershed - Land Management Change Estimated Total Reduction in P 100% Manure Control ~ % 80% Manure Reduction ~ 8 10 % 60% Manure Reduction ~ 6 8 % 25% Manure Increase ~ % No Manure & Perennial Crops ~ % Urban TSS Reduction ~ %

14 SWAT Modeling Summary Described nutrient and sediment loading variability in both time and space Prioritized sub-watershed areas for nutrient control practices Evaluated whole watershed loading responses to major load reduction measures

15 Watershed Remediation Flow Chart - Field-scale Analysis - Pheasant Branch Field-scale pilot project Watershed Scale analysis - SWAT Field-scale analysis SNAP Plus Relative ranking of sub-areas Implement management practices Evaluate lake water quality Goal met Goal not met

16 Wisconsin Phosphorus Index (WPI) - Part of SNAP Plus A tool to rank fields for runoff P loss potential The WPI is used throughout WI for nutrient management planning and is familiar to producers, LCD staff and crop consultants Field 2 Field 1 Stream

17 Research Base for P Index Simulated rainfall runoff trials with different managements and soils ( > 500 plot events). Replicated small plots with long-term natural runoff collectors, different managements and soils (100 plots) Year-round runoff monitoring in field-scale watersheds with different soils and management (21 sites)

18 WPI Estimates Average Annual P Loss from Agricultural Fields to Perennial Streams Soil erosivity and soil test P Land slope and slope length Average annual climate Fertilizer and manure application Crop and tillage type

19 WI Phosphorus Index Map - Pheasant Branch Watershed Pilot -

20 WI Phosphorus Index Distribution - Pheasant Branch Watershed Pilot Frequency P - Index Value 18 21

21 What can SNAP Plus & WPI do at the field scale?? WPI MdC2 (Slope 9%) Tillage is SC-N-N-N-SC-SC-SC As-A-A-A-Cg-Cg-Cs OfAs-A-A-A-Cg-Cg-Cs As-A-A-A-Cs-Cg-Cg OfAs-A-A-A-Cs-Cg-Cg SNAP Plus the WPI can evaluate Year Manure Application the impact of crop rotation and tillage on P losses 7.0 WPI Liquid, Surface Liquid, Incorporated Solid, Surface Solid, Incorporated also the impact of manure and application method on P losses Manure P Added (Lbs)

22 SNAP Plus / WPI Modeling Summary Rank fields by sediment and P loss. Evaluate alternative field-scale Mgmt. practices to reduce P loss. - tillage, fertilizer, manure and cropping systems Work toward percent reduction goals identified by the watershed model. Use an adaptive management strategy.