CREATING SOLUTIONS FOR A CHANGING WORLD Watershed Runoff Analysis April 18, 2017 John Melack, UCSB Ed Beighley & Dongmei Feng, Northeastern University
Study Workflow Civil and Environmental Engineering Daily P&T (>100 km grid) 10 GCM s 1950-2100 RCP 4.5&8.5 Measurements Daily P&T (6 km grid) Gauge-Based 1950-2013 Daily Q USGS 1984-2013 Land Cover Soil Properties Topography Downscaled Climatology Daily P&T (6 km grid) 10 GCM s 1950-2100 RCP 4.5&8.5 Calibrated Hydro-Model Hillslope River Routing (HRR) Hydro-Model Parameter Calibration Land Cove-Based Parameter Transfer Functions Regional Hydro-Model Simulated Streamflow Historical Q 1950-2005 10 GCM s Future Q 2006-2100 10 GCM s RCP 4.5&8.5 Projected Q 2006-1961 2045-2100 10 GCM s RCP 4.5&8.5
Study Region ID USGS No. Station name Start Date End Date Area (km 2 ) G1 11119500 Carpinteria Creek 1941/1/1/ current 33.9 G2 11119745 Mission Creek, Rocky Nook 10/28/1983 current 17.1 G3 11119750 Mission Creek, Mission St. 10/1/1970 current 21.7 G4 11119940 Maria Ygnacio Creek 10/1/1970 current 14.3 G5 11120000 Atascadero Creek 1941/1/1/ current 49.0 G6 11119780 Arroyo Burro Creek 10/1/1970 9/30/1993 17.2 G7 11120510 San Jose Creek 10/1/1970 9/30/2000 24.4 G8 11120550 Gaviota Creek 10/1/1966 9/30/1986 48.7
Focus Drainage Systems Civil and Environmental Engineering Area Landcover distribution (%) ID Name (km 2 ) Developed Forest Shrubland Herbaceous Planted W1 Devereux Slough 9.0 67 2 4 21 4 W2 Goleta Slough* 123 35 26 26 7 6 W3 Arroyo Burro 25.5 38 33 25 3 1 W4 Mission 30.0 45 35 19 1 0 W5 Santa Monica/Franklin 18.3 22 40 29 5 3 W6 Carpinteria 45.4 10 48 29 3 9 * Goleta Slough includes: Atascadero, Los Canaros, Maria Ygnacio, San Jose, San Pedro, and Tecolotito Creeks
Hydro-Model calibrated based on gauge-based Precip & Temp Results at USGS stream gauge locations
Hydro-Model calibrated based on gauge-based Precip & Temp Results at USGS stream gauge locations ID USGS No. Bias (%) E p (%) RM G1 11119500 9.4-14 0. G2 11119745-1.9 5.0 0. G3 11119750 4.2 0.1 0. G4 11119940-11 -9.1 0. G5 11120000-9.3-26 0.
Future Climate Impacts on Streamflow Hydrologic model calibrated at gauge locations Model parameters transferred to un-gauged watersheds Simulated streamflow based downscaled GCM precipitation and temperature for all coastal watersheds From Climate Study no change in annual precipitation From Watershed Study?
Median change (%) in annual runoff (Qm) for RCP 4.5 & 8.5 Drainage System ID 2006-2061 2045-2100 Devereux Slough 1 12 18 25 43 Goleta Slough* 2 11 15 23 38 Arroyo Burro 3 6 16 22 39 Mission 4 5 16 21 39 Santa Monica/Franklin 5 11 13 22 32 Carpinteria 6 11 13 21 28 Coast wc 10 13 26 42 Changes shaded gray for RCP 8.5 Change in annual runoff (Qm) 2006-2061 RCP4.5 Max Median of upper half, Q3 Median for all values (5 above - 5 below) Median of lower half, Q1 Min Statistics based on changes resulting from 10 GCMs
Median change (%) in annual peak discharge (Qp) for RCP 4.5 & 8.5 Drainage System ID 2006-2061 2045-2100 Devereux Slough 1 20 17 24 32 Goleta Slough* 2 22 20 36 44 Arroyo Burro 3 17 14 29 44 Mission 4 17 10 25 38 Santa Monica/Franklin 5 22 12 36 41 Carpinteria 6 20 11 36 39 Coast wc 34 19 67 99 Changes shaded gray for RCP 8.5 Change in annual peak flow (Qp) 2006-2061 RCP4.5 Max Median of upper half, Q3 Median for all values (5 above - 5 below) Median of lower half, Q1 Min Statistics based on changes resulting from 10 GCMs
Median change (%) in 100-yr flood discharge for RCP 4.5 & 8.5 Drainage System Name 2006-2061 RCP 4.5 RCP 2045-2100 8.5 ID P 2006-2061 Q m 2045-2100 Q p 2006-2061 P Q2045-2100 m Q p Devereux Slough W1 1-2 12-22 18 20-4 17 3 491 25 435 24 32 Goleta Slough* W2 1-3 11 47 15 2240 20 2 960 23 3869 36 44 Arroyo Burro W3 0-3 637 16 1777 14 1 1202 22 39 110 29 44 Mission W4 0-3 531 16 1792 10 1 862 21 39 120 25 38 Santa Monica/Franklin W5 0-2 119 13 2237 12 1 4 2 22 3245 36 41 Carpinteria W6 0-1 11-2 13 2047 11 2 103 21 2855 36 39 Coast 0-3 10 13 34 19 1 1 26 42 67 99 Change in Q 100-yr 2006-2061 RCP4.5 Max Median of upper half, Q3 Median for all values (5 above 5 below) Median of lower half, Q1 Min Statistics based on changes resulting from 10 GCMs
Future Climate Impacts on Streamflow From Climate Study No change in annual precipitation From Watershed Study Increases in streamflow WHY?
Median change (%) in rainy season duration for RCP 4.5 & 8.5 Drainage System Name ID 2006-2061 2006-2061 2045-2100 2045-2100 P Start Q m End Q p Duration P Start Q m QEnd p Duration Devereux Slough W1 1-2 15 1213 18 0 20-2 17-8 3-91 25 28 4326 241 32-2 -11-15 Goleta Slough* W2 1-3 17 1114 15 1 22-2 20-8 2-90 23 30 3827 361 44-2 -10-14 Arroyo Burro W3 0-3 17 6 14 16 0 17-2 14-8 1-92 22 30 3930 291 44-1 -11-12 Mission W4 0-3 17 5 14 16 0 17-2 10-7 1-92 21 30 3930 251 38-1 -11-13 Santa Monica/Franklin W5 0-2 16 1113 13 0 22-2 12-7 1-112 22 27 328 361 410-10 -14 Carpinteria W6 0-16 1113 13 0 20-3 11-7 2-113 21 27 2827 361 390-11 -14 Coast Coast 0-3 16 1013 13 0 34-3 19-8 1-101 26 29 426 671 990-10 -13 Change in annual rainy season duration 2006-2061 RCP4.5 Max Changes shaded gray for RCP 8.5 Median of upper half, Q3 Median for all values (5 above 5 below) Median of lower half, Q1 Min Statistics based on changes resulting from 10 GCMs
Median change (%) in rainfall event characteristics for RCP 4.5 2006-2061 (%) 2045-2100 (%) 2045-2100 Drainage System Name P <15 15-45 Q >45 All <15 15-45 >45 All m Q p P Q m Q p ID mm/d mm/d mm/d events mm/d mm/d mm/d events Devereux Slough 1-2 12 18 20 17 3 1 25 43 24 32 W1-12 -6 17-8 -15-10 36-9 Goleta Slough* 1-3 11 15 22 20 2 0 23 38 36 44 W2-11 -6 19-7 -14-11 29-10 Arroyo Burro W3 0-8-3 6-8 165 17-6 14-14 1-9 2 2022-9 39 29 44 Mission W4 0-9-3 5-9 1611 17-6 10-15 1-9 2 2021-9 39 25 38 Santa Monica/Franklin W5 0-7-2 11-15 1318 22-6 12-15 1-13 2 1122-9 32 36 41 Carpinteria W6 0-11 -1 11-10 13 13 20-7 11-14 2-11 3 1221-9 28 36 39 Coast 0-3 10 13 34 19 1 1 26 42 67 99 Coast -9-7 18-7 -13-10 24-7 Change in number rain events >45 mm/d 2006-2061 RCP4.5 Max Median of upper half, Q3 Median for all values (5 above 5 below) Median of lower half, Q1 Min Statistics based on changes resulting from 10 GCMs
Summary Changes based on GCM derived values for 2006-2061 or 2045-2100 relative to GCM derived values for 1950-2005 Median value from model ensembles used for assessment Precipitation relatively unchanged (-3 to +3%) Duration of rainy season decreases (7 to 15%) Number of large rainfall events increases (4 to 77%) Runoff increase (5 to 43%) Peak annual streamflow increase (10 to 44%) Potential large changes in 100-yr flood flow (-22 to 120%) Emission scenarios result in similar changes with higher emissions (RCP 8.5) generally resulting in larger changes