Manoa Watershed Runoff By: Mari Doi, Travis Voeller, Kiku Mochimaru, Victor Lee, Boyd Mackenzie, Rebecca Mierzejewski, Daniel Mehrez, Will Couture
Objectives • Calculate runoff for Manoa watershed (60 grids) using Curve # Method and base flow • RO-the amount of precipitation that is unavailable for groundwater recharge
Model Runoff using the Curve Number Method Each grid assigned a CN number based on the dominant current land cover. Soil properties and hydrologic condition were taken into consideration.
Model Runoff • CN for Antecedent Moisture conditions (I & III) assigned. • ROMatrix program used to determine model runoff for each grid using: -CN -Actual Rainfall
Calculate estimated stream flow • Find the average runoff of all 60 grid squares for each day • Multiply by area of the watershed to get volume of discharge
Determining Baseflow Look at the average minimum stream flow on days with no rainfall From the runoff found from ROmatrix, get average and multiply it by the area of the watershed to get volume of runoff Look at difference of the measured and modeled stormflow
Calculate weighted base flow • Find average rainfall for each grid • Find average rainfall for all grids • Base flow for grid= (average rainfall per grid)/ (average rainfall for all grids * average base flow)
Conclusion • Adjusted curve #’s & added base flow provided us with the most efficient results of basin RO • RO results can then be plugged into water balance equation as an output of water Runoff was calculated by obtaining precipitation data and utilizing the curve number method. By adjusting the curve numbers and adding base flow, the data was a close representation the model data from the USGS results.