Water Quality Index for Agricultural Runoff (WQIag)

Transcription

1 Water Quality Index for Agricultural Runoff (WQIag) By Harbans Lal, Environmental Engineer National Water Quality/Quantity Team, WNTSC/USDA-NRCS, Portland, OR and Brooks Engelhardt, Resource Conservationist USDA-NRCS, Oxnard, CA Outline Definition of an Index & its Common Uses Complexity of Water Quality Parameters WQI (Water Quality Index) WQIag (Water Quality I ndex for Agricultural Runoff) Justification Components Description & Procedure Demo Current and Potential Usages (Case Study from California by Brooks Engelhardt) Concluding Remarks and Future Plans Helping People Help Land Definition of Index A dimensionless number that combines multiple variables into a single value representing the overall condition (measure) of something Traditionally used for financial and other systems (Dow J, NASDAQ, Happiness Index, GDP Index, etc.) Easy to understand and follow Indices and their General Usage

2 Water Quality (WQ) A complex representation of multiple factors Includes parameters such as DO, ph, Turbidity, BOD, COD, Ecoli, Temp, Nutrients (N & P) and many more WQ Parameters expressed in different units (ppm, number, etc.) and measured in different ranges Hard to understand and follow by non professionals Felt need for a simple tool for expressing WQ WQI (Water Quality Index) Thus, the concept of the Water Quality Index (WQI) is introduced The concept is adopted by many state, national and international agencies including the US EPA, OR DEQ, India, Canada, FAO of the UN. How we got involved? A short story! Water Quality Index (WQI) A dimensionless number that combines the values of multiple water quality factors such as DO, ph, BOD, COD, Ecoli, Temp, Nutrients (N & P), etc. into a single value by normalized subjective rating curves Primarily used for evaluating the quality of water in rivers, streams and lakes, etc. Multiple models (Review Paper) No Index for Agricultural Runoff Water

3 Review Paper Agriculture Needs & Pollutes Water Agriculture Uses Major Portion of Freshwater Agriculture is the Major Source of Freshwater Pollution Helping People Help Land NRCS Programs for Improving and Maintaining water quality USDA/NRCS spends big moneys on conservation programs for improving water quality from agricultural and forested area NRCS always looking for tools for evaluating the effectiveness of its conservation programs Helping People Help Land

4 Justification Tools for evaluating effectiveness of conservation practices for improving water quality Available Tools Planning and Assessment Tool (e.g. CPPE) Modeling (CEAP, RUSLE2, etc.) Edge of Field (EoF) Monitoring Tools either too generic or too expensive Needed a tool that uses site-specific information and multiple factors with least cost Thus, need for a Water Quality Index for Agricultural Runoff (WQIag) was recognized Got us started on this project with intensive literature review and consultation with multiple disciplinary experts` Water Quality Index for Agricultural Runoff (WQIag) Web based WQIag

5 Water Quality Index for Agricultural Runoff (WQIag) Web based WQIag What it is? A tool for ranking runoff water from agricultural fields (1 to 10): 10 being the best Simple and easy to use web-based system Uses multiple field characteristics and management factors Weighting for different factors for local preferences Site-specific weather data with the possibility of customization Components Field physical /sensitivity factors Nutrient management Tillage management Pest management Irrigation / Drainage management Conservation practices

6 Description & Procedure Multiple factors in some of the components Ranks and combines factors within a component Ranks and combines different components WQIag# based upon 4-key components Adjusting WQIag# based upon drainage/irrigation type Adjusting WQIag# based upon conservation practices Demo Current and Potential Uses Use of the Runoff Water Quality Index in Ventura County, CA Brooks Engelhardt Resource Conservationist USDA NRCS

7 WQI tool used to evaluate runoff in a citrus orchard located on sloped land in a Mediterranean Climate Field location Setting: mature lemon orchard loam soil 5% 9% slopes minimal ground cover in the alleys micro sprinkler irrigation tree rows up and down slope Field location Resource Concerns: - sheet and rill erosion, estimate soil loss = >6 tons/ac/yr. RUSLE2 - irrigation induced erosion - irrigation runoff -storm runoff, sediment transport WQI benchmark = 5.67 Field location

8 Benchmark WQI output: 5.67 Soils data is from the Web Soil Survey Selected Medium Veg Cover, Considers: tree canopy, shredded prunings on orchard floor sprinkler irrigation and No till Lemon orchard treated with cover crop Planted: November, 2012 Cover crop growth in spring March 2013 April 2013

9 WQI output increased 5.67 to 5.85, changing to High Veg. Cover WQI output increased to 7.30 Adding conservation cover (planting reseeding, cool season annual grasses) RUSLE 2 estimated soil loss from sheet and rill erosion Benchmark condition: >6 tons/ac/year Planned condition (adding cover crop): <1 ton/ac/year Other Current and Potential Uses NRCS-National Water Quality Initiative State WQIag WQIag WQIag with Trend Conservat -ion Colorado Hawaii 5.08 Idaho 3.43 Indiana 5.92 Minnesota Oklahoma Integrated into FieldPrint Calculator of Field2Market Baseline Criteria for Water Quality Trading Possibility of Many More Applications and Usage Concluding Remarks WQIag an index for quick assessment with least cost Incorporates professional knowledge and local preferences through weighting factors Low cost, Low Rigor, High Intensity Usage Tool Highly useful when actual monitoring is out of reach

10 Future Plans Re-designing nutrient management component and tile drainage system Extending WQIag framework at the whole farm and watershed level Working with the Idaho National Lab of the US- DOE) to link WQIag to their LEAF framework for evaluating water quality at landscape level Calibration with actual monitoring data and other models Our Motto To be innovative in solving water problems?