Biological and Environmental Engineering Soil & Water Research Group Spatial Variability of Groundwater Soluble Phosphorous on an Alluvial Valley-Fill Aquifer and Connection to Stream Quality in the Catskill Mountains Francisco Flores-Lopez Zachary M. Easton Tammo S. Steenhuis Cornell University Biological and Environmental Engineering

Soil & Water Research Group Groundwater monitoring of SRP levels in agricultural fields and connection to stream quality is the major consideration in this study Objective To develop a farm-scale groundwater flow model and incorporate data regarding spatial variability of SRP to describe and predict SRP transport To identify critical management groundwater areas that may affect the stream SRP concentrations To assess the influence of these high risk groundwater areas on stream flow SRP concentrations

Biological and Environmental Engineering Soil & Water Research Group Site Layout, Water Samples and Data Analysis Soluble Reactive Phosphorous Modeling of the Groundwater Flow (Visual ModFlow) and SRP Tracking Pathlines (MODPATH)Modeling of the Groundwater Flow (Visual ModFlow) and SRP Tracking Pathlines (MODPATH) Steady State ConditionsSteady State Conditions Geostatistical Analysis of Groundwater SRP – Kriging Interpolation by SeasonsGeostatistical Analysis of Groundwater SRP – Kriging Interpolation by Seasons Relationship between Groundwater SRP Spatial Variability and Stream QualityRelationship between Groundwater SRP Spatial Variability and Stream Quality Valley bottom dairy farm in the Cannonsville Reservoir Watershed Valley bottom dairy farm in the Cannonsville Reservoir Watershed 22 Piezometers 22 Piezometers Depths from 0.3 to 1.5 m Depths from 0.3 to 1.5 m 542 groundwater samples (06/2004 – 04/2006) 542 groundwater samples (06/2004 – 04/2006) 22 Capacitance probes (Data Loggers) 22 Capacitance probes (Data Loggers) 1 hr intervals 1 hr intervals 4 Stream Sampling Sites 4 Stream Sampling Sites 146 stream water samples 146 stream water samples Sampling once every two weeks Sampling once every two weeks - base flow conditions -

Biological and Environmental Engineering Soil & Water Research Group Results –SRP Concentrations (mg L -1 ) Season# of SamplesMinimumMaximumMeanSE of MeanSkewness Groundwater Summer Fall Winter Spring Creek B Summer Fall Winter Spring

Biological and Environmental Engineering Soil & Water Research Group Results – Modeling of Groundwater Flow (ModFlow) Correlation coefficient for the calibrated steady state and observed average water table height: r 2 = 0.76 Average groundwater table depth = 0.6 m Maximum depth: Summer (0.72 m) Minimum depth: Spring (0.50 m) SRP tracking: - P21 shortest travel distance: 30 m - P8 longest travel distance : 420 m - Seven of the 22 piezometers influenced Creek B (P10, P12, P15, P17, P21, P22, and P27)

Biological and Environmental Engineering Soil & Water Research Group Results – Predicted Groundwater SRP Maps at 10-m Cell Size Resolution

Biological and Environmental Engineering Soil & Water Research Group Results – Predicted Groundwater SRP and Distance to Streams

Biological and Environmental Engineering Soil & Water Research Group Results – Stream Quality Creek B fed by groundwater [GW & SW not statistically different (p=0.876)] Stream sampling at “base flow” = 75% water samples < 0.03 mg L -1 => Background groundwater SRP

Biological and Environmental Engineering Soil & Water Research Group Conclusions We identified critical management groundwater zones where high SRP concentrations may be reaching streams Best management practices should be implemented in riparian areas (targeting hydrological pathways) to improve water quality Results demonstrate the importance of identifying processes that describe groundwater and stream flow interactions

Biological and Environmental Engineering Soil & Water Research Group Thank you !!!