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.

Grid Land Cover Level I Land Cover Level II % Land Cover Level II CN Value II CN Value I CN Value III 1 3 Rangeland 32 Shrub and Brush Rangeland 100% 86 71 95 2 4 Forest Land 42 Evergreen Forest land 1% 83 67 93 99% 79 62 90 3 4 77 59.5 89.5 5 6 7 25% 75% 8 9 10 11 60 40 78 12 13 89% 11% 69 50 84 14 49% 66 46 51%

Model Runoff CN for Antecedent Moisture conditions (I & III) assigned. ROMatrix program used to determine model runoff for each grid using: -CN -Actual Rainfall

Total Runoff (mm) 1 2 3 0-100mm 4 5 6 7 8 9 100-200mm 10 11 12 13 14   0-100mm 4 5 6 7 8 9 100-200mm 10 11 12 13 14 15 16 200-300mm 17 18 19 20 21 22 23 300-400mm 24 25 26 27 28 29 400-500mm 30 31 32 33 34 35 500-600mm 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Use ROMatrix.exe to find estimated runoff for each grid cell

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

Adjust curve numbers to optimize runoff estimates

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)

% Runoff from Total Precipitation

% Runoff from Precipitation

Total Rainfall vs. Total Runoff

Conclusion 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. 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