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33597 (4)06 IE 335 G'� J. C. Green & Associates 38 -647 Nasturtium Way Palm Desert, CA 92211 (760) 799 -3086 Coral Mountain Subdivision Hydrology and Hydraulic Calculations City of La Quinta Riverside County California JO JCGA0515 December 2005 Revised as directed February 200;6 1 of 9 Background The proposed Coral Mountain Subdivision located southwest of the intersection of Avenue 60 Madison Street in the City of La Quinta. Most of the subdivision drains to the northeast comer of the property to a large retention basin. On completion the subdivision will contain 57 lots. 11. Purpose The purpose of these calculations is to make an estimate of the size of the retention pond needed to serve the subdivision and adjacent tributary areas. I. Calculations The calculations which follow are in the form of Excel spreadsheets based upon the Riverside County Flood Control and Water Conservation District, Hydrology Manual, April 1978. The City also requires that ponds be provided with 1 foot of freeboard above the design water level and include one or more sand filters to prevent clogging of the underlying sandy soil. Previous studies have demonstrated that the maximum required retention volume results from a storm of 24 hours duration. Good practice generally requires that the designer use the best, most reliable and current information available. The most reliable precipitation data for the Coachella Valley may be found at the NOAA website noted below. Notwithstanding, the City of La Quinta requires designers to use an arbitrary 24 hour precipitation of 4.5 inches. Calculations for both the NOAA data and the City's value are presented to illustrate the difference in required volume which is about 19 percent. Sheet 1 Grading Plan Sheets 2 -7 Preliminary Retention Calculations Sheet 8 Hydrology Manual Plate D-5.2 Precipitation Data (NOAH) http: //Www.nws.noaa.gov /oh /hdsc 9 Of 2 + - Y .. *� ., � a + i � -, + G�A. mot. � .. T ... . ,, r � .. � .. �' 7 f � � � 4• � r �. ' �� i, ` �, M rcfcdret.xls Date: 10 -20 -05 Design: rwf Project: Coral Mountain Subdivision (TTM 33597) Check: Location: La Quinta, CA Job No. JCGA0515 Client: R.T. Hughes C. LLC & J.C. Green & Associates Revised 2 -12 -06 Conceptual Site Plan Attached PRELIMINARY RETENTION CALCULATIONS - SUMMARY Site Data: Pervious Area 17.19 Ac 748800 SF 50.00% Imperv. Area 17.19 748800 50.00% Totals 34.38 Ac 1497600 SF 100.00% See Sketch Below La Quinta Retention Criteria Whitewater River watershed Design for 1 % Annual Exceedance Probability (AEP) storm Retain difference between undeveloped and developed runoff volume Rational C varies see RCFCD Plate D -5.2 (attached) Soil Type Hyd. Group A and B (Myoma & Gilman Soils) Use B for design w/ AMC II Percolation Rate ( RCFCD PI. E-6.2) = Assumed 0 -inch per hour Inflow= CIA ( Modified Method) Critical Duration Duration - hours Rainfall - inches Undev. Peak Q - cfs Dev. Peak Q -cfs Undevel. Volume -d Developed Volume -cf Difference - cf 24" 24- 3.8 4.5 4.2 5.7 10.15 12.37 64413 87662 246732 297556 182320 209894 "NOAA Website "La Quinta arbitrary standard C/L Avenue 60 - -------------------•-------------- 1920- + /=---------------------- - -• - -- Coral Mountain Subdiv.- 22.97 Ac. ' C/L Madison St 1560' +/- Top of Levee i BASIN SKETCH Area estimated conservatively to account for off -site drainage Project: Coral Mountain Subdivision Undeveloped vs. Developed Hydrographs - 24 Hour Storm 1 % AEP Rainfall = 3.8 inches Area = 34.38 Undevelo ed. Developed Time Time Percent Intensity C Inflow Incr. Vol. C Inflow Incr. Vol. Step min Rain in/hr cfs cf cfs cf 1 15 0.2 0.03 0.03 0.03 27 0.47 0.50 446 2 30 0.3 0.05 0.04 0.06 51 0.48 0.75 673 3 45 0.3 0.05 0.04 0.06 51 0.48 0.75 673 4 60 0.4 0.06 0.04 0.09 81 0.48 1.00 904 5 75 0.3 0.05 0.04 0.06 51 0.48 0.75 673 6 90 0.3 0.05 0.04 0.06 51 0.48 0.75 673 7 105 0.3 0.05 0.04 0.06 51 0.48 0.75 673 8 120 0.4 0.06 0.04 0.09 81 0.48 1.00 904 9 135 0.4 0.06 0.04 0.09 81 0.48 1.00 904 10 150 0.4 0.06 0.04 0.09 81 0.48 1.00 904 11 165 0.4 0.06 0.04 0.09 81 0.48 1.00 904 12 180 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 13 195 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 14 210 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 15 225 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 16 240 0.6 0.09 0.06 0.18 162 0.49 1.53 1375 17 255 0.6 0.09 0.06 0.18 162 0.49 1.53 1375 18 270 0.7 0.11 0.06 0.24 213 0.49 1.79 1615 19 285 0.7 0.11 0.06 0.24 213 0.49 1.79 1615 20 300 0.8 0.12 0.07 0.30 269 0.49 2.06 1858 21 315 0.6 0.09 0.06 0.18 162 0.49 1.53 1375 22 330 0.8 0.12 0.07 0.30 269 0.49 2.06 1858 23 345 0.8 0.12 0.07 0.30 269 0.49 2.06 1858 24 360 0.9 0.14 0.08 0.37 332 0.50 2.34 2104 25 375 0.9 0.14 0.08 0.37 332 0.50 2.34 2104 26 390 0.9 0.14 0.08 0.37 332 0.50 2.34 2104 27 405 1.0 0.15 0.09 0.45 402 0.50 2.61 2353 28 420 1.0 0.15 0.09 0.45 402 0.50 2.61 2353 29 435 1.0 0.15 0.09 0.45 402 0.50 2.61 2353 30 450 1.1 0.17 0.09 0.53 478 0.50 2.89 2605 31 465 1.2 0.18 0.10 0.62 559 0.51 3.18 2860 32 480 1.3 0.20 0.11 0.72 647 0.51 3.46 3118 33 495 1.5 0.23 0.12 0.93 841 0.52 4.05 3642 34 510 1.5 0.23 0.12 0.93 841 0.52 4.05 3642 35 525 1.6 0.24 0.13 1.05 947 0.52 4.34 3908 36 540 1.7 0.26 0.13 1.18 1059 0.52 4.64 4177 37 555 1.9 0.29 0.15 1.44 1299 0.53 5.25 4723 38 570 2.0 0.30 0.15 1.59 1428 0.53 5.56 5000 39 585 2.1 0.32 0.16 1.74 1562 0.53 5.87 5279 40 600 2.2 0.33 0.16 1.89 1701 0.54 6.18 5561 41 615 1.5 0.23 0.12 0.93 841 0.52 4.05 3642 43 44 46 47 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81. 90 91 630 1.5 0.23 0.12 0.93 841 0.52 4.05 3642 645 2.0 0.30 0.15 1.59 1428 0.53 5.56 5000 660 2.0 0.30 0.15 1.59 1428 0.53 5.56 5000 675 1.9 0.29 0.15 1.44 1299 0.53 5.25 4723 690 1.9 0.29 0.15 1.44 1299 0.53 5.25 4723 705 1.7 0.26 0.13 1.18 1059 0.52 4.64 4177 720 1.8 0.27 0.14 1.31 1176 0.53 4.94 4448 735 2.5 0.38 0.18 2.39 2152 0.55 7.14 6423 750 2.6 0.40 0.19 2.57 2313 0.55 7.46 6715 765 2.8 0.43 0.20 2.94 2650 0.55 8.12 7307 780 2.9 0.44 0.21 3.14 2826 0.56 8.45 7606 795 3.4 0.52 0.24 4.20 3779 0.57 10.15 9138 810 3.4 0.52 0.24 4.20 3779 0.57 10.15 9138 825 2.3 0.35 0.17 2.05 1846 0.54 6.50 5846 840 2.3 0.35 0.17 2.05 1846 0.54 6.50 5846 855 2.7 0.41 0.20 2.75 2479 0.55 7.79 7010 870 2.6 0.40 0.19 2.57 2313 0.55 7.46 6715 885 2.6 0.40 0.19 2.57 2313 0.55 7.46 6715 900 2.5 0.38 0.18 2.39 2152 0.55 7.14 6423 915 2.4 0.36 0.18 2.22 1997 0.54 6.81 6133 930 2.3 0.35 0.17 2.05 1846 0.54 6.50 5846 945 1.9 0.29 0.15 1.44 1299 0.53 5.25 4723 960 1.9 0.29 0.15 1.44 1299 0.53 5.25 4723 975 0.4 0.06 0.04 0.09 81 0.48 1.00 904 990 0.4 0.06 0.04 0.09 81 0.48 1.00 904 1005 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1020 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1035 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 1050 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 1065 0.5 0.08 0.05 0.13 118 0.48 1.26 1138 1080 0.4 0.06 0.04 0.09 81 0.48 1.00 904 1095 0.4 0.06 0.04 0.09 81 0.48 1.00 904 1110 0.4 0.06 0.04 0.09 81 0.48 1.00 904 1125 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1140 0.2 0.03 0.03 0.03 27 0.47 0.50 446 1155 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1170 0.4 0.06 0.04 0.09 81 0.48 1.00 904 1185 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1200 0.2 0.03 0.03 0.03 27 0.47 0.50 446 1215 0.3 0.05 0.04 0.06 51 0.48 0.75 6731 1230 0.3 0.05 0.04 0.06 51 0.48 0.75 673' 1245 0.3 0.05 0.04 0.06 51 0.48 0.75 673, 1260 0.2 0.03 0.03 0.03 27 0.47 0.50 446 1275 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1290 0.2 0.03 0.03 0.03 27 0.47 0.50 446 1305 0.3 0.05 0.04 0.06 51 0.48 0.75 673 1320 0.2 0.03 0.03 0.03 27 0.47 0.50 446 1335 0.3 0.05 0.04 0.06 51 0.48 0.75 673 11350 0.2 0.03 0.03 0.03 27 0.47 0.50 446' 1365 0.2 0.03 0.03 0.03 27 0.47 0.50 446 92 1380 0.2 0.03 0. 93 1395 0.2 0.03 0. 94 1410 0.2 0.03 0. 95 1425 0.2 0.03 0. 96 1440 0.1 0.02 0. Totals 3.8 ChkSum 100.0 3.80 Peak 0.52 in/hr Project: Coral Mountain Subdivision 0.03 27 0.47 0.50 446 0.03 27 0.47 0.50 446 0.03 27 0.47 0.50 446 0.03 27 0.47 0.50 446 0.01 10 0.47 0.25 221 64413 246732 4.20 cfs 10.15 cfs Required Vol. (cf) = 182,320 Undeveloped vs. Developed Hydrographs - 24 Hour Stone 1 % AEP Rainfall = 4.5 inches Area = 34.38 Undevelo ed Develo ed Time Time Percent Intensity C Inflow Incr. Vol. C Inflow Incr. Vol. Step min Rain in/hr cfs cf cfs cf 1 15 0.2 0.04 0.03 0.04 35 0.48 0.59 529 2 30 0.3 0.05 0.04 0.07 67 0.48 0.89 801 3 45 0.3 0.05 0.04 0.07 67 0.48 0.89 801 4 60 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 5 75 0.3 0.05 0.04 0.07 67 0.48 0.89 801 6 90 0.3 0.05 0.04 0.07 67 0.48 0.89 801 7 105 0.3 0.05 0.04 0.07 67 0.48 0.89 801 8 120 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 9 135 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 10 150 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 11 165 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 12 180 0.5 0.09 0.06 0.18 159 0.49 1.51 1356 13 195 0.5 0.09 0.06 0.18 159 0.49 1.51 1356 14 210 0.5 0.09 0.06 0.18 159 0.49 1.51 1356 15 225 0.5 0.09 0.06 0.18 159 0.49 1.51 1356 16 240 0.6 0.11 0.07 0.24 218 0.49 1.82 1641 17 18 19 20 21 24 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 CVl 51 5� 5; 54 5! 5E 57 5E 5E 6C 61 64 65 255 0.6 0.11 0.07 0.24 218 0.49 1.82 1641 270 0.7 0.13 0.07 0.32 287 0.49 2.14 1929 285 0.7 0.13 0.07 0.32 287 0.49 2.14 1929 300 0.8 0.14 0.08 0.41 365 0.50 2.47 2222 315 0.6 0.11 0.07 0.24 218 0.49 1.82 1641 330 0.8 0.14 0.08 0.41 365 0.50 2.47 2222 345 0.8 0.14 0.08 0.41 365 0.50 2.47 2222 360 0.9 0.16 0.09 0.50 451 0.50 2.80 2519 375 0.9 0.16 0.09 0.50 451 0.50 2.80 2519 390 0.9 0.16 0.09 0.50 451 0.50 2.80 2519 405 1.0 0.18 0.10 0.61 546 0.51 3.13 2820 420 1.0 0.18 0.10 0.61 546 0.51 3.13 2820 435 1.0 0.18 0.10 0.61 546 0.51 3.13 2820 450 1.1 0.20 0.11 0.72 650 0.51 3.47 3125 465 1.2 0.22 0.11 0.85 762 0.51 3.82 3434 480 1.3 0.23 0.12 0.98 882 0.52 4.16 3746 495 1.5 0.27 0.14 1.28 1148 0.52 4.87 4384 510 1.5 0.27 0.14 1.28 1148 0.52 4.87 4384 5251 1.6 0.29 0.15 1.44 1292 0.53 5.23 4708 5401 1.7 0.31 0.15 1.61 1445 0.53 5.60 5036 555 1.9 0.34 0.17 1.97 1773 0.54 6.34 5703 570 2.0 0.36 0.17 2.17 1949 0.54 6.71 6042 585 2.1 0.38 0.18 2.37 2131 0.55 7.09 6385 600 2.2 0.40 0.19 2.58 2322 0.55 7.48 6730 615 1.5 0.27 0.14 1.28 1148 0.52 4.87 4384 630 1.5 0.27 0.14 1.28 1148 0.52 4.87 4384 645 2.0 0.36 0.17 2.17 1949 0.54 6.71 6042 660 2.0 0.36 0.17 2.17 1949 0.54 6.71 6042 675 1.9 0.34 0.17 1.97 1773 0.54 6.34 5703 690 1.9 0.34 0.17 1.97 1773 0.54 6.34 5703 705 1.7 0.31 0.15 1.61 1445 0.53 5.60 5036 720 1.8 0.32 0.16 1.78 1605 0.54 5.96 5368 735 2.5 0.45 0.21 3.26 2935 0.56 8.65 7789 750 2.6 0.47 0.22 3.50 3153 0.56 9.05 8148 765 2.8 0.50 0.23 4.01 3610 0.57 9.86 8876 780 2.9 0.52 0.24 4.28 3848 0.57 10.27 9245 795 3.4 0.61 0.27 5.70 5134 0.59 12.37 11135 810 3.4 0.61 0.27 5.70 5134 0.59 12.37 11135 825 2.3 0.41 0.20 2.80 2519 0.55 7.87 7080 840 2.3 0.41 0.20 2.80 2519 0.55 7.87 7080 855 2.7 0.49 0.22 3.75 3378 0.57 9.46 8510 870 2.6 0.47 0.22 3.50 3153 0.56 9.05 8148 885 2.6 0.47 0.22 3.50 3153 0.56 9.05 8148 900 2.5 0.45 0.21 3.26 2935 0.56 8.65 7789'. 915 2.4 0.43 0.20 3.03 2723 0.56 8.26 7433' 930 2.3 0.41 0.20 2.80 2519 0.55 7.87 7080 945 1.9 0.34 0.17 1.97 1773 0.54 6.34 5703 960 1.9 0.34 0.17 1.97 1773 0.54 6.34 5703 975 0.4 0.07 0.05 0.12 108 0.48 1.20 1076 990 0.4 0.071 0.051 0.12 108 0.48 1.20 1076 , 71 74 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 Totals ChkSum Peak 1005 0.3 0.05 0.04 1020 0.3 0.05 0.04 1035 0.5 0.09 0.06 1050 0.5 0.09 0.06 1065 0.5 0.09 0.06 1080 0.4 0.07 0.05 1095 0.4 0.07 0.05 1110 0.4 0.07 0.05 1125 0.3 0.05 0.04 1140 0.2 0.04 0.03 1155 0.3 0.05 0.04 1170 0.4 0.07 0.05 1185 0.3 0.05 0.04 1200 0.2 0.04 0.03 1215 0.3 0.05 0.04 1230 0.3 0.05 0.04 1245 0.3 0.05 0.04 1260 0.2 0.04 0.03 1275 0.3 0.05 0.04 1290 0.2 0.04 0.03 1305 0.3 0.05 0.04 1320 0.2 0.04 0.03 1335 0.3 0.05 0.04 1350 0.2 0.04 0.03 1365 0.2 0.04 0.03 1380 0.2 0.04 0.03 1395 0.2 0.04 0.03 1410 0.2 0.04 0.03 1425 0.2 0.04 0.03 1440 0.1 0.02 0.02 4.5 100.0 4.50 0.61 in/hr 0.07 67 0.48 0.89 801 0.07 67 0.48 0.89 801 0.18 159 0.49 1.51 1356 0.18 159 0.49 1.51 1356 0.18 159 0.49 1.51 1356 0.12 108 0.48 1.20 1076 0.12 108 0.48 1.20 1076 0.12 108 0.48 1.20 1076 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.07 67 0.48 0.89 801 0.12 108 0.48 1.20 1076 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.07 67 0.48 0.89 801 0.07 67 0.48 0.89 801 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.07 67 0.48 0.89 801 0.04 35 0.48 0.59 529 0.04 35 0.48 0.59 529 0.04 35 0.48 0.59 529 0.04 35 0.48 0.59 529 0.04 35 0.48 0.59 529 0.04 35 0.48 0.59 529 0.01 131 0.471 0.291 262 87662 297556 5.70 cfs 12.37 cfs Required Vol. (cf) = 209,895 U O LL Is 1% AEP Storm Hydrographs -100 100 30Q 500 700 900 1100 1300 1500 Time - minutes . t Developed Conditions Hydrographs 4.5 inch total rainfall 3.8 inch total rainfall 0 rl-n+- W,rf4rr%1t%nw Unniani Plata n-j; 9 BcVS1.x1S Comm. / Industrial MHP Apartments Condos !SFR 0.25 Acre SFR 0.5 Acre SFR -1 Acre Undeveloped jCj = 0.0037d - 0.050212 +0.2277i+0.467 Ci = 0.009313 -0.1158i2 +0.4875i+.014 11 am V Rational C in/hr Undev SFR 1 Ac SFR .5 Ac SFR .25 Ac Condo MHP APT Comm./Ind Pct. Imp.> 0 20 40 50 65 75 80 90 0 0.000 0.180 0.360 0.450 0.580 0.670 0.720 0.810 1 0-430 0.530 0.620 0.670 0.740 0.780 0.810 0.850 2 0.590 0,650 0.710 0.750 0.790 0.820 0.840 0.870 3 0.660 0.710 0.760 0.780 0.820 0.840 0.850 0.880 4 0.710 0.750 0.790 0.810 0,830 0.850 0,860 0.885 5 0.745 0.780 0.810 0.820 0.845 0.860 0.865 0.890 6 0.770 0.790 0.820 , 0.830 0.850 , 0.870 0.880 0.895 Comm. / Industrial MHP Apartments Condos !SFR 0.25 Acre SFR 0.5 Acre SFR -1 Acre Undeveloped jCj = 0.0037d - 0.050212 +0.2277i+0.467 Ci = 0.009313 -0.1158i2 +0.4875i+.014 11 am V Precipitation Frequency Data Server http:// hdsc. nws. noaa. gov /cgi- bin/hdsc/buildout.perl? type-- pf &series=pd&units= us&state:.. POINT PRECIPITATION 6�'"' FREQUENCY ESTIMATES $ FROM NOAH ATLAS 14 California 33.61185 N 116.2667 W 104 feet from "Precipitation- Frequency Atlas of the United States" NOAA Atlas 14, Volume 1, Version 3 G.M. Bonnin, D. Todd, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland, 2003 Extracted: Mon Feb 6 2006 Confidence Limits 1 Seasonality I Location Maps Other Info. I GIS data I Maps I Help Docs I U.S. Map Precipitation Frequency Estimates (inches) ARI* (years) 5 10: min min _ 0.13:0.20 0.21; 0.32 0.28 0.42 [0.38: 0.58 [0 K. 48 0.73 x0 59 0 90 0.73'[3 11 0.94 [I 43 1.13 1.73 15' 30 60 120: 3 min min min min hr 0.25.0.34 0.42 i 6 O.bS 0.39; f 0 53 0.66 0.87 �0 97 [0.52.0.70 0.87 1.12 1.25 72`10.97 [1.21 1.52 [1.66! (0 91:1.22 1.51 1.86 [2.01 1.12 1.51 1.87 2.26 2.40 137 .85 [�2 29 2.71 2 85 1.77 2.39 [2.96 3.41 [3 52 [2-1 4 I 8 3.57 I4 04 4 11 [4.53 6 hr 12 24 hr hr 48 f 4 hr day 10 20 day 30 [day ' 45 60 day , day, [-2 0.84 1.25 1.57_1.90 [2.04 x2.42 2.84 �3 30 r3 97 1.03 111; 1.52 (1.68; 2.11 [2:42 [2.74 2.84 [3.25 [3 29 [3.80 �3 77 4 39 [5.54 4.45 5 25 5.00 [5 95 __ 1.23 [1.34 1.47 1.56. 1.70' 1 89 2.07 x2.27 2.40 2.63 �2 43 [2.65,[2 90 r3 0808 [3.35 [3.23 [3.52 13.81.4.06 4.38 3.92 x4.25 (4 57': 4.88;[5.23 4 68' 5.07 �5 41:5.77 6.15: 5.97 6.32 [6.75 7.14 6.82 7.32 7.65 8.19 8.58 7.92 8.47 [8.77 9,40.9.77 i [F86-J2 .10 ° 2.28 3.54 ' -13.54 324 5 10 25 2.87 3.65 .4.11 4.74 63 6.59 5.31 6.26 7.28 8.35 4.50 [5.83 (6.90 [8.04 19.24 [� 50 100 200 500 1000 7.61 (9.07 .9.86 t 2 11 06 10.94 12.31 Text version of table * These precipitation frequency estimates are based on a partial duration series. ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting forces estimates near zero to appear as zero. 7IFl7nnr% 1 •77 DX4 Precipitation Frequency Data Server http://hdsc.nws.noaa.govlcgi-binlhdsclbuildout.perl?type=pf&series=pd&units=us&state,.,. Partial duration based Point Prooipitation Frequenoy Estimates Version: 3 33.61185 H 116.2667 W 104 ft min 20 30 40 50 80100 140 200 300 Average Reourrenoe, Interval (years) 4-day 7-dao, 0 -d ly -A-- 20-dau 0 500 700 1000 'Ylf;l')Of)C, 1 -1) YJkA 13 10 T CL 7 C 0 CL 4 L 3 Kim 2 3 4 5 6 78910 Man Feb 06 16121s14 2006 min 20 30 40 50 80100 140 200 300 Average Reourrenoe, Interval (years) 4-day 7-dao, 0 -d ly -A-- 20-dau 0 500 700 1000 'Ylf;l')Of)C, 1 -1) YJkA Precipitation Frequency Data Server 14 9 .0 40 CL 7 0 6 ro -P 4 L 3 Q. http,:Ilhdsc.nws.noaa.govlcgi-binlhdsclbuildout.pefl?type=pf&sefies--pd&units=us&state... Partial duration based Point Precipitation Frequency Estimates Versions 3 33.61185 h 116.2667 N 104 ft Average Recurrence Interval (Mears) Igo t% Confidence Limits - Upper bound of the 90% confidence interval Precipitation Frequency Estimates (inches) 20 J-i i 45 12 24 48 4 7 10 Fidif-��F 5 30 6 1 da (years) min mill min min in hr hr hr hr hr day day day da., day da:3 Fmili i9 1'1-.-8-3- ­- 12.0-0 .10.25 F1 1 70 [0. .03 017 0.3 0.4210.52 10. j 1.4611.59 11.73 2.18 2.47 --j-0 26 [0.39 0 1.0611,18 11.5411.85 12.01 2.2312.46 2.66 82 3.36 3.79 1 i I F L L L L L z ? 2 z% M ZI V a 42 I I I lu M 10 1 Cu 00 It 1 0 1 1 1 1 1 1 1 1 1 1 N 0 J) 0 0 0 CU A It 0) 1. th 11 .4 0 0 1 J, 0 M `O 0% Duration — (U M V �b Mon Feb 06 16121:14 2006 Average Recurrence Interval (Mears) Igo t% Confidence Limits - Upper bound of the 90% confidence interval Precipitation Frequency Estimates (inches) 20 J-i i 45 12 24 48 4 7 10 Fidif-��F 5 30 6 1 da (years) min mill min min in hr hr hr hr hr day day day da., day da:3 Fmili i9 1'1-.-8-3- ­- 12.0-0 .10.25 F1 1 70 [0. .03 017 0.3 0.4210.52 10. j 1.4611.59 11.73 2.18 2.47 --j-0 26 [0.39 0 1.0611,18 11.5411.85 12.01 2.2312.46 2.66 82 3.36 3.79 1 i I F Precipitation Frequency Data Server http: //hdsc.nws.noaa.gov /cgi- bin /hdsc/buildout.perl? type =pf&series= pd&units=us&state.; . 10 0.34. 0.52 0.64. 0.86 1.07 1.36: 1.52 1.93: 2.31 2.53 2.8713.15 13.39 3.61 13.93 4.28 14.80 5.26 25 0.47 0.72 0.89 1.20 (1.48 1.83 2.01 12.50. 2.94 3.27 3.81 14.18 4.47 14 75 5.14 5.57 16 83 50 0.59 0.89 1.11 1.49 1.85.12.25 2.43 2.97 3.46 3.89 4.635.06 5.37 ' 5.71 6.14 6.62 17.36 18 10 1^100 0.73 1-1.11:11.37 1.85 2.29 2.72: 2.92 3.50 4.01; 4.561-5.5416.05 6.38 16.77 17 23 7.78 8.59 9.47 200 10 8911.3511.68 2.26 2.80 3.28 3.48 4.07 4.61:x5 30 6.5817.17 7.49 17.95 8.44 : 9.04 19 90 10.90. 500 11 1511.76 2.18.2_93 3.63 4.16 4.35 4.95:x5.47 6.3818 16 8.86 9.20- 9.70 :x10.20 10.87.11 i.78113;00 (1000.1.4012.13 2.6513.56, 4.41, 4.9---4 J5-11'5.69 6.21 17.27 9 52110.32'F- 0 32 10 65 11.21 11.71 12.39.113.31' 14.70 •The upper bound of the confidence Interval at 90% confidence level is the value which 5% of the simulated quantile values for a given frequency are greater than. These precipitation frequency estimates are based on a partial duration series. ARI is the Average Recurrence Interval. Please refer to the documentation for more Information. NOTE: Formatting prevents estimates near zero to appear as zero. Lower bound of the 90% confidence interval 1 Precipitation Frequency Estimates (inches) iARI ** 5 10 15 . 30 60 ' 120' 3 6 12 24 48 . 4 7 10 20 : 30 45 : [-60 (years) min min. min: min min hr hr hr 1 hr , hr day day day day day day' day i 2 -F--i-.107 1 10 21 0.28 10.341 -0.46 0.54 6 69 0.8410.93 1.04 ,11.14 1.24 1.32 1.43 11 59:x1.7811.93' 5 0.17 1'-0 2 0 32 0.43 0.541 7 0.81 11 03,11.24 11 40 1.59 ` 1.75 1.91 2.03: 2.22 244; 2.7412 98s 10 10 22.00 34: 0.42 [0-.5-610.70 .. 0.92 102; 1.28 11.53'11.75 12 05' 2.23 2.43 2.60.2.81 3.09:.. .3.77 25 0.30 10.46 0.57 0.7710.95 11 23 11 35:11.64 1.94 2.26 2.69 2.94 3.16.3.39 3.65 4.00; 4.45 4.86 -- _ __ x -50 0.38`10.57 10 71 10.9511.1811 48 11.60,11.93' 2.26 12 65 3.23 3.51 ' 3.75 4.03 14 33 14.72 5.23 15 71 0 0.46 0.69 10.86 1.16 1.43 1.76 1.89 �25 12.58 13.08 13.81 4.13 4.40 4.72 15 04 15 49 6.03; 6.59 1 200 V 0.54 K. 1 02 1.38 1.71 2.08 2 21 2.56 12 92 13.51 14.44 4.81 15.07 15.45 5.81 6.2816.87 7.50 x 500 0.68 1.03 1.28 1.72 12 13 12 54 2.65 13.02 X3.38 4.13:5.36 5.78 6.03 4 6.86 7.38 8.01 8.77 1 1000 0.79 1.21 (1.50 202.12.50 2.92 3.02 13 ^38 13.75 �62 6.12 6.58 6.82 7.36 7.71 18 2618 89` 9.78 • The lower bound of the confidence interval at 90% confidence level is the value which 5% of the simulated quantile values for a given frequency are less than. •• These precipitation frequency estimates are based on a partial duration maxima series. ARI is the Average Recurrence Interval. Please refer to the documentation for more information. NOTE: Formatting prevents estimates near zero to appear as zero. Maps - 7./A /7(1(1A 1.7.7 PM Precipitation Frequency Data Server i Other Maps/Photographs - 1 QO"il 71 fi � ?°d61 http: //hdsc.nws. noaa. gov/ cgi- bin/hdsc/buildout.perl ?type=pf &series =pd &units= us&state... E i nese maps were p=uoea usmg a aireat map request Tram me U.S. Census, Bureau Mapping and Cartographic Resources Tinter Map Server, All Pie e read disclaimer for more information. LEGEND �. #xx —° State Connector x H ivjhwayT v County Oman Scale 1:220503 lo 2 6 i kn 8 ni *averaft- -true scale d pends on monitoAreesol A"on View USGS = ital orthovhoto auadranigle (DOO covering this location from TerraServer; USGS Aerial Photograph may also be available from this site. A DOQ is a computer- generated image of an aerial photograph in which image displacement caused by terrain relief and camera tilts has been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. Visit the National Digital Orthophoto Pro_gam DOW) for more information. 2/6/7006 1.22 PM Precipitation Frequency Data Server http-: // hdsc. nws. noaa .gov /cgi- bin / hdsc /buildout. perl ?type=pf&series= pd&units==us&state .. Watershed/Stream Flow Information - Find the Watershed for this location using the U.S. Environmental Protection Agency's site. Climate Data Sources - Precipitation frequency results are based on data from a variety of sources, but largely NCDC. The following links provide general information about observing sites in the area, regardless of if their data was used in this study. For detailed information about the stations used in this study, please refer to our documentation. Using the National Climatic Data Center's (NCDC) station search engine, locate other climate stations within: +/ -30 minutes ...OR... +/ -1 degree of this location (33.61185/- 116.2667). Digital ASCII data can be obtained directly from NCDC. Find Natural Resources Conservation Service (MRCS) SNOTEL (SNOwpack TELemetry) stations by visiting the Western Regional Climate Center's state - specific SNOTEL station maps. Hydrometeorological Design Studies Center DOC/NOMINational Weather Service . 1325 East -West Highway Silver Spring, MD 20910 (301) 713 -1669 Questions ?: HDSC.Questions(&,,noaa.gov Disclaimer 1 /l. MAA4 1 •7'1 D11A Malaga Riverside County Hydrology Manual Concentration Point NA Area Designation NA Area (acres) Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I I 0.1 333333 11-ag (hr) = 1 0.0 SHORTCUT METHOD Less than 100 -200 acrelsqmi e < 7 -8 min) Elev @Headwater 1 Elev @Concentration Point 0 S (fUmile)= 7.5 Soil Group (Sheet 11/ pp 78) n (Ave Mann, Plate E.3) B Lag (min) 0.1 Storm Frequency (10, 25, 100) Precipitation Rate (PI E5.1 -5.6) 2.5 La Quinta Zone (1 to 6) 6 Duration 3, 6, 24 Area Precip Corr (E5.8 ( %)) 100.00 Total Adjusted Storm = 2.50 Runoff Index (PI E -6.1) 56 AMC Condition (I, II, or III (Sheet E -8)) 2 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.51 Devel Area Cover (PI 6.3) 58% Const Loss Rate, F (3 -6 hr storm) 0.24 Fm, Min Low Loss 50 -75% of F 0.12 Low Loss Rate Percent 3 & 6hr : 0.90 Results 183695 Cubic Ft 4.2 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cuft) (cuft) (cuft) 5 1.3 0.39 0.24 0.24 0.15 0.0 0 0 10 1.3 0.39 0.24 0.24 0.15 4.2 1265 1265 15 1.1 0.33 0.24 0.24. 0.09 2.5 743 2008 20 1.5 0.45 0.24 0.24 0.21 6.0 1787 3796 25 1.5 0.45 0.24 0.24 0.21 6.0 1787 5583 30 1.8 0.54 0.24 0.24 0.30 8.6 2570 8153 35 1.5 0.45 0.24 0.24 0.21 6.0 1787 9940 40 1.8 0.54 0.24 0.24 0.30 8.6 2570 12510 45 1.8 0.54 0.24 0.24 0.30 8.6 2570 15080 50 1.5 0.45 0.24 0.24 0.21 6.0 1787 16868 55 1.6 0.48 0.24 0.24 0.24 6.8 2048 18916 60 1.8 0.54 0.24 0.24 0.30 8.6 2570 21486 65 2.2 0.66 0.24 0.24 0.42 12.0 3614 25100 70 2.2 0.66 0.24 0.24 0.42 12.0 3614 28714 75 2.2 0.66 0.24 0.24 0.42 12.0 3614 32329 80 2.0 0.60 0.24 0.24 0.36 10.3 3092 35421 85 2.6 0.78 0.24 0.24 0.54 15.5 4658 40079 90 2.7 0.81 0.24 0.24 0.57 16.4 4919 44998 95 2.4 0.72 0.24 0.24 0.48 13.8 4136 49134 100 2.7 0.81 0.24 0.24 0.57 16.4 4919 54053 105 3.3 0.99 0.24 0.24 0.75 21.6 6485 60539 110 3.1 0.93 0.24 0.24 0.69 19.9 5963 66502 115 2.9 0.87 0.24 0.24 0.63 18.1 5441 71943 120 3.0 0.90 0.24 0.24 0.66 19.0 5702 77645 125 3.1 0.93 0.24 0.24 0.69 19.9 5963 83608 130 4.2 1..26 0.24 0.24 1.02 29.4 8834 92443 135 5.0 1.50 0.24 0.24 1.26 36.4 10922 103365 140 3.5 1.05 0.24 0.24 0.81 23.4 7007 110372 145 6.8 2.04 0.24 0.24 1.80 52.1 15620 125992 150 7.3 2.19 0.24 0.24 1.95 56.4 16925 142917 155 8.2 2.46 0.24 0.24 2.22 64.2 19274 162191 160 5.9 1.77 0.24 0.24 1.53 44.2 13271 175463 165 2.0 0.60 0.24 0.24 0.36 10.3 3092 178555 170 1.8 0.54 0.24 0.24 0.30 8.6 .2570 181125 _ 175 1.8 0.54 0.24 0.24 0.30 8.6 2570 183695 180 0.6 0.18 0.24 0.16 0.02 0.5 0 183695 0 0.0 0.00 0.24 0.00 0.00 0.0 0 183695 Data Input (boxed is calced) Concentration Point NA Area Designation NA Area (acres) 29 L (miles) 0.1 333333 Lca (miles) 0.1 Elev @Headwater 1 Elev @Concentration Point 0 S (fUmile)= 7.5 n (Ave Mann, Plate E.3) 0.0015 Lag (min) 0.1 Storm Frequency (10, 25, 100) 100 La Quinta Zone (1 to 6) 6 Duration 3, 6, 24 3 Page 1 Malaga 10_3_07 Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD Lag (hr) = 0.0 SHORTCUT METHOD Less than 100 -200 acres & La Time < 7 -8 min) Data Input (boxed is calced) Concentration Point NA Soil Group (Sheet 11/ pp 78) C Area Designation NA Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres) 25.8 0.04 sqmi Area Precip Corr (E5.8 ( %)) I 1 1 100.00 L (miles) 1 0.1333333 1 Total Adjusted Storm = 1 2.50 Lca (miles) 0.1 1 Runoff Index (PI E -6.1) 1 1 69 Elev @ Headwater 1 JAMC Condition (I, II, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.37 F-Fs =� 7-(ft/mH 1 1 Devel Area Cover (PI 6.3) 1 55% le ) =1j 7.5 Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) I 1 0.1 Low Loss Rate Percent 3 & 6hr : 0.90 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 178484 Cubic Ft Duration 3, 6, 24 3 4.1 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cult) (cult) (cuft) 5 1.3 0.39 0.19 0.19 0.20 0.0 0 0 10 1.3 0.39 0.19 0.19 0.20 5.2 1568 1568 15 1.1 0.33 0.19 0.19 0.14 3.7 1104 2673 20 1.5 0.45 0.19 0.19 0.26 6.8 2033 4705 25 1.5 0.45 0.19 0.19 0.26 6.8 2033 6738 30 1.8 0.54 0.19 0.19 0.35 9.1 2729 9468 35 1.5 0.45 0.19 0.19 0.26 6.8 2033 11501 40 1.8 0.54 0.19 0.19 0.35 9.1 2729 14230 45 1.8 0.54 0.19 0.19 0.35 9.1 2729 16960 50 1.5 0.45 0.19 0.19 0.26 6.8 2033 18992 55 1.6 0.48 0.19 0.19 0.29 7.6 2265 21258 60 1.8 0.54 0.19 0.19 0.35 9.1 2729 23987 65 2.2 0.66 0.19 0.19 0.47 12.2 3658 27645 70 2.2 0.66 0.19 0.19 0.47 12.2 3658 31304 75 2.2 0.66 0.19 0.19 0.47 12.2 3658 34962 80 2.0 0.60 0.19 0.19 0.41 10.6 3194 38156 85 2.6 0.78 0.19 0.19 0.59 15.3 4587 42743 90 2.7 0.81 0.19 0.19 0.62 16.1 4819 47562 95 2.4 0.72 0.19 0:19 0.53 13.7 4123 51685 100 2.7 0.81 0.19 0.19 0.62 16.1 4819 56504 105 3.3 0.99 0.19 0.19 0.80 20.7 6212 62716 110 3.1 0.93 0.19 0.19 0.74 19.2 5748 68465 115 2.9 0.19 0.19 0.68 17.6 5284 73748 120 3.0 0.19 0.19 0.71 18.4 5516 79264 125 3.1 N1.26 0.19 0.19 0.74 19.2 5748 85012 130 4.2 0.19 0.19 1.07 27.7 8302 93314 135 5.0 0.19 0.19 1.31 33.9 10160 103474 140 3.5 1.05 0.19 0.19 0.86 22.3 6677 110151 145 6.8 2.04 0.19 0.19 1.85 47.8 14339 124491 150 7.3 2.19 0.19 0.19 2.00 51.7 15500 139991 155 8.2 2.46 0.19 0.19 2.27 58.6 17590 157581 160 • 5.9 1.77 0.19 0.19 1.58 40.8 12250 169831 165 2.0 0.60 0.19 0.19 0.41 10.6 3194 173025 170 1.8 0.54 0.19 0.19 0.35 9.1 2729 175754 175 1.8 0.54 0.19 0.19 0.35 9.1 2729 178484 180 0.6 1 0.18 0.19 0.16 0.02 0.5 0 178484 0 0.0 1 0.00 0.19 0.00 0.00 1 0.0 0 178484 Page 1 Malaga 2_26_08 Riverside County Hydrology Manual Concentration Point 0 Area Designation 0 Area (acres) Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I L (miles) 0 Lag (hr) _ #DIV /0! SHORTCUT METHOD Less than 100 -200 acres & La 2 Time < 7 -8 min) Elev @Headwater 0 Elev @Concentration Point 0 H =� 0 S (fUmile)= #DIV /0! Soil Group (Sheet 11/ pp 78) n (Ave Mann, Plate E.3) A Lag (min) #DIV /O! Storm Frequency (10, 25, 100) Precipitation Rate (PI E5.1 -5.6) 2.5 La Quinta Zone (1 to 6) 6 Duration 1, 3, 6, 24 Area Precip Corr (E5.8 ( %)) 100.00 Total Adjusted Storm = 2.50 Runoff Index (PI E -6.1) 72.978 AMC Condition (I, II, or III (Sheet E -8)) 2 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.34 Devel Area Cover (PI 6.3) 50% 17728 Const Loss Rate, F (3 -6 hr storm) 1 0.19 Fm, Min Low Loss 50 -75% of F1 0.09 Low Loss Rate Percent 3 & 6hr : 0.50 Results 187627 Cubic Ft 4.31 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cult) (cuft) (cuft) 5 1.3 0.39 0.19 0.19 0.20 0.0 0 0 10 1.3 0.39 0.19 0.19 0.20 5.5 1652 1652 15 1.1 0.33 0.19 0.19 0.14 3.9 1164 2816 20 1.5 0.45 0.19 0.19 0.26 7.1 2140 4956 25 1.5 0.45 0.19 0.19 0.26 7.1 2140 7095 30 1.8 0.54 0.19 0.19 0.35 9.6 2871 9967 35 1.5 0.45 0.19 0.19 0.26 7.1 2140 12107 40 1.8 0.54 0.19 0.19 0.35 9.6 2871 14978 45 1.8 0.54 0.19 0.19 0.35 9.6 2871 17849 50 1.5 0.45 0.19 0.19 0.26 7.1 2140 19989 55 1.6 0.48 0.19 0.19 0.29 7.9 2384 22373 60 1.8 0.54 0.19 0.19 0.35 9.6 2871 25244 65 2.2 0.66 0.19 0.19 0.47 12.8 3847 29091 70 2.2 0.66 0.19 0.19 0.47 12.8 3847 32938 75 2.2 0.66 0.19 0.19 0.47 12.8 3847 36785 80 2.0 0.60 0.19 0.19 0.41 11.2 3359 40144 85 2.6 0.78 0.19 0.19 0.59 16.1 4823 44967 90 2.7 0.81 0.19 0.19 0.62 16.9 5067 50034 95 2.4 0.72 0.19 0.19 0.53 14.4 4335 54368 100 2.7 0.81 0.19 0.19 0.62 16.9 5067 59435 105 3.3 0.99 0.19 0.19 0.80 21.8 6530 65965 110 3.1 0.93 0.19 0.19 0.74 20.1 6042 72007 115 2.9 0.87 0.19 0.19 0.68 18.5 5554 77561 120 3.0 0.90 0.19 0.19 0.71 19.3 5798 83359 125 3.1 0.93 0.19 0.19 0.74 20.1 6042 89402 130 4.2 1.26 0.19 0.19 1.07 29.1 8725 98127 135 5.0 1.50 0.19 0.19 1.31 35.6 10676 108803 140 3.5 1.05 0.19 0.19 0.86 23.4 7018 115820 145 6.8 2.04 0.19 0.19 1.85 50.2 15066 130887 150 7.3 2.19 0.19 0.19 2.00 54.3 16286 147173 155 8.2 2.46 0.19 0.19 2.27 61.6 18481 165654 160 5.9 1.77 0.19 0.19 1.58 42.9 12871 178525 165 2.0 0.60 0.19 0.19 0.41 11.2 3359 181884 170 1.8 0.54 0.19 0.19 0.35 9.6 2871 184756 175 1.8 0.54 0.19 0.19 0.35 9.6 2871 187627 180 0.6 0.18 0.19 0.09 0.09 2.4 0 187627 0 0.0 0.00 0.19 0.00 0.00 0.0 0 187627 Data Input (boxed is calced) Concentration Point 0 Area Designation 0 Area (acres) 27.1 0.0 sgmi L (miles) 0 Lca (miles) 0 Elev @Headwater 0 Elev @Concentration Point 0 H =� 0 S (fUmile)= #DIV /0! n (Ave Mann, Plate E.3) 0.0015 Lag (min) #DIV /O! Storm Frequency (10, 25, 100) 100 La Quinta Zone (1 to 6) 6 Duration 1, 3, 6, 24 3 hr Page 1 Malaga 2_26_08 Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I Lag (hr) _ #DIV /0! SHORTCUT METHOD Less than 100 -200 acres & Lag Time < 7 -8 min) Data Input (boxed is calced) Concentration Point 0 Soil Group (Sheet 11/ pp 78) A Area Designation 0 Precipitation Rate (PI E5.1 -5.6) 3.8 Area (acres) 27.1 0.0 sqmi Area Precip Corr (E5.8 ( %)) I 1 100.00 E(miles) 1 0 1 1 Total Adjusted Storm = 1 3.75 Lca (miles) 0 Runoff Index (PI E -6.1) 1 1 72.978 Elev @ Headwater 0 AMC Condition (I, II, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.34 H = 0 Devel Area Cover (PI 6.3) 1 50% S (fUmile)= #DIV /0! 17728__l Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) I #DIV /0! Low Loss Rate Percent 3 & 6hr : 0.50 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 173990 Cubic Ft Duration 1, 3, 6, 24 24 hr 3.99 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) N (in /hr) (in /hr) (cfs) (cuft) (cuft) (cult) 15 0.2 0.03 0.33 0.02 0.02 0.0 0 0 30 0.3 0.05 0.32 0.02 0.02 0.6 549 549 45 0.3 0.05 0.32 0.02 0.02 0.6 549 1098 60 0.4 0.06 0.32 0.03 0.03 0.8 732 1829 75 0.3 0.05 0.31 0.02 0.02 0.6 549 2378 90 0.3 0.05 0.31 0.02 0.02 0.6 549 2927 105 0.3 0.05 0.31 0.02 0.02 0.6 549 3476 120 0.4 0.06 0.19 0.03 0.03 0.8 732 4207 135 0.4 0.06 0.30 0.03 0.03 0.8 732 4939 150 0.4 0.06 0.29 0.03 0.03 0.8 732 5671 165 0.5 0.08 0.29 0.04 0.04 1.0 915 6585 180 0.5 0.08 0.29 0.04 0.04 1.0 915 7500 195 0.5 0.08 0.28 0.04 0.04 1.0 915 8415 210 0.5 0.08 0.28 0.04 0.04 1.0 915 9329 225 0.5 0.08 0.28 0.04 0.04 1.0 915 10244 240 0.6 0.09 0.27 0.05 0.05 1.2 1098 11341 255 0.6 0.09 0.27 0.05 0.05 1.2 1098 12439 270 0.7 0.11 0.27 0.05 0.05 1.4 1280 13719 285 0.7 0.11 0.26 0.05 0.05 1.4 1280 15000 300 0.8 0.12 0.26 0.06 0.06 1.6 1463 16463 315 0.6 0.09 0.26 0.05 0.05 1.2 1098 17561 330 0.7 0.11 0.25 0.05 0.05 1.4 1280 18841 345 0.8 0.12 0.25 0.06 0.06 1.6 1463 20305 360 0.8 0.12 0.25 0.06 0.06 1.6 1463 21768 375 0.9 0.14 0.24 0.07 0.07 1.8 1646 23414 390 0.9 0.14 0.24 0.07 0.07 1.8 1646 25061 405 1.0 0.15 0.24 0.08 0.08 2.0 1829 26890 420 1.0 0.15 0.23 0.08 0.08 2.0 1829 28719 435 1.0 0.15 0.23 0.08 0.08 2.0 1829 30548 450 1.1 0.17 0.23 0.08 0.08 2.2 2012 32561 465 1.2 0.18 0.22 0.09 0.09 2.4 2195 34756 480 1.3 0.20 0.22 0.10 0.10 2.6 2378 37134 495 1.5 0.23 0.22 0.22 0.01 0.2 183 37317 510 1.5 0.23 0.21 0.21 0.01 0.3 257 37574 525 1.6 0.24 0.21 0.21 0.03 0.8 696 38270 540 1.7 0.26 0.21 0.21 0.05 1.3 1135 39405 555 1.9 0.29 0.21 0.21 0.08 2.2 1939 41344 Page 1 Malaga 2_26_08 Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD Lag (hr) _ #DIV /0! SHORTCUT METHOD Less than 100 -200 acres & Lag Time < 7 -8 min ) Data Input (boxed is calced) Concentration Point 0 Soil Group (Sheet 11/ pp 78) A Area Designation 0 Precipitation Rate (PI E5.1 -5.6) 3.8 Area (acres) 27.1 0.0 sgmi Area Precip Corr (E5.8 ( %)) 1 100.00 L (miles) 1 0 Total Adjusted Storm = 3.75 Lca (miles) 0 Runoff Index (PI E -6.1) 1 72.978 Elev @ Headwater 0 AMC Condition (I, II, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.34 H = 0 Devel Area Cover (PI 6.3) 50% _ S (ft/mile) =l #DIV /0! 17728 Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) I I #DIV 101 Low Loss Rate Percent 3 & 6hr : 0.50 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 173990 Cubic Ft Duration 1, 3, 6, 24 24 hr 3.99 JAcre - Ft Unit Time Pattern Storm Loss Rates Effective I Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cuft) (cult) (cu-ft) 15 0.2 0.03 0.33 0.02 0.02 0.0 0 0 30 0.3 0.05 0.32 0.02 0.02 0.6 549 549 45 0.3 0.05 0.32 0.02 0.02 0.6 549 1098 60 0.4 0.06 0.32 0.03 0.03 0.8 732 1829 75 0.3 0.05 0.31 0.02 0.02 0.6 549 2378 90 0.3 0.05 0.31 0.02 0.02 0.6 549 2927 105 0.3 0.05 0.31 0.02 0.02 0.6 549 3476 120 0.4 0.06 0.19 0.03 0.03 0.8 732 4207 135 0.4 0.06 0.30 0.03 0.03 0.8 732 4939 150 0.4 0.06 0.29 0.03 0.03 0.8 732 5671 165 0.5 0.08 0.29 0.04 0.04 1.0 915 6585 180 0.5 0.08 0.29 0.04 0.04 1.0 915 7500 195 0.5 0.08 0.28 0.04 0.04 1.0 915 8415 210 0.5 0.08 0.28 0.04 0.04 1.0 915 9329 225 0.5 0.08 0.28 0.04 0.04 1.0 915 10244 240 0.6 0.09 0.27 0.05 0.05 1.2 1098 11341 255 0.6 0.09 0.27 0.05 0.05 1.2 1098 12439 270 0.7 0.11 0.27 0.05 0.05 1.4 1280 13719 285 0.7 0.11 0.26 0.05 0.05 1.4 1280 15000 300 0.8 0.12 0.26 0.06 0.06 1.6 1463 16463 315 0.6 0.09 0.26 0.05 0.05 1.2 1098 17561 330 0.7 0.11 0.25 0.05 0.05 1.4 1280 18841 345 0.8 0.12 0.25 0.06 0.06 1.6 1463 20305 360 0.8 0.12 0.25 0.06 0.06 1.6 1463 21768 375 0.9 0.14 0.24 0.07 0.07 1.8 1646 23414 390 0.9 0.14 0.24 0.07 0.07 1.8 1646 25061 405 1.0 0.15 0.24 0.08 0.08 2.0 1829 26890 420 1.0 0.15 0.23 0.08 0.08 2.0 1829 28719 435 1.0 0.15 0.23 0.08 0.08 2.0 1829 30548 450 1.1 0.17 0.23 0.08 0.08 2.2 2012 32561 465 1.2 0.18 0.22 0.09 0.09 2.4 2195 34756 480 1.3 0.20 0.22 0.10 0.10 2.6 2378 37134 495 1.5 0.23 0.22 0.22 0.01 0.2 183 37317 510 1.5 0.23 0.21 0.21 0.01 0.3 257 37574 525 1.6 0.24 0.21 0.21 0.03 0.8 696 38270 540 1.7 0.26 0.21 0.21 0.05 1.3 1135 39405 555 1 1.9 0.29 0.21 0.21 0.08 2.2 1939 41344 Page 1 Malaga 2_26_08 (3) Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I Lag (hr) _ #DIV /0! SHORTCUT METHOD Less than 100 -200 acres & Lag Time < 7 -8 min) Data Input (boxed is calced) Concentration Point 0 Soil Group (Sheet 11/ pp 78) A Area Designation 0 Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres) 27.1 0.0 sqmi Area Precip Corr (E5.8 ( %)) 1 100.00 L (miles) 1 0 1 Total Adjusted Storm = 2.50 Lca (miles) 0 IRunoff Index (PI E -6.1) 1 72.978 Elev @ Headwater 0 AMC Condition (I, Il, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 llnfiltr Rate for Pery Areas (PI E -6.2) Fp 0.34 R 0 Devel Area Cover (PI 6.3) 50% S (ft/mile) =� #DIV /0! 17728 Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) I I #DIV /0! Low Loss Rate Percent 3 & 6hr : 0.50 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 187627 Cubic Ft Duration 1, 3, 6, 24 3 hr 4.31 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood .Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cuft) (cult) (cuft) 5 1.3 0.39 0.19 0.19 0.20 0.0 0 0 10 1.3 0.39 0.19 0.19 0.20 5.5 1652 1652 15 1.1 0.33 0.19 0.19 0.14 3.9 1164 2816 20 1.5 0.45 0.19 0.19 0.26 7.1 2140 4956 25 1.5 0.45 0.19 0.19 0.26 7.1 2140 7095 30 1.8 0.54 0.19 0.19 0.35 9.6 2871 9967 35 1.5 0.45 0.19 0.19 0.26 7.1 2140 12107 40 1.8 0.54 0.19 0.19 0.35 9.6 2871 14978 45 1.8 0.54 0.19 0.19 0.35 9.6 2871 17849 50 1.5 0.45 0.19 0.19 0.26 7.1 2.140 19989 55 1.6 0.48 0.19 0.19 0.29 7.9 2384 22373 60 1.8 0.54 0.19 0.19 0.35 9.6 2871 25244 65 2.2 0.66 0.19 0.19 0.47 12.8 3847 29091 70 2.2 0.66 0.19 0.19 0.47 12.8 3847 32938 75 2.2 0.66 0.19 0.19 0.47 12.8 3847 36785 80 2.0 0.60 0.19 0.19 0.41 11.2 3359 40144 85 2.6 0.78 0.19 0.19 0.59 16.1 4823 44967 90 2.7 0.81 0.19 0.19 0.62 16.9 5067 50034 95 2.4 0.72 0.19 0.19 0.53 14.4 4335 54368 100 2.7 0.81 0.19 0.19 0.62 16.9 5067 59435 105 3.3 0.99 0.19 0.19 0.80 21.8 6530 65965 110 3.1 0.93 0.19 0.19 0.74 20.1 6042 72007 115 2.9 0.87 0.19 0.19 0.68 18.5 5554 77561 120 3.0 0.90 0.19 0.19 0.71 19.3 5798 83359 125 3.1 0.93 0.19 0.19 0.74 20.1 6042 89402 130 4.2 1.26 0.19 0.19 1.07 29.1 8725 98127 135 5.0 1.50 0.19 0.19 1.31 35.6 10676 108803 140 3.5 1.05 0.19 0.19 0.86 23.4 7018 115820 145 6.8 2.04 0.19 0.19 1.85 50.2 15066 130887 150 7.3 2.19 0.19 0.19 2.00 54.3 16286 147173 155 8.2 2.46 0.19 0.19 2.27 61.6 18481 165654 160 5.9 1.77 0.19 0.19 1.58 42.9 12871 178525 165 2.0 0.60 0.19 0.19 0.41 11.2 3359 181884 170 1.8 0.54 0.19 0.19 0.35 9.6 2871 184756 175 1.8 0.54 0.19 0.19 0.35 1 1 9.6 2871 187627 180 0.6 0.18 0.19 0.09 0.09 2.4 0 187627 0 0.0 1 0.00 0.19 1 0.00 0.00 0.0 0 187627 Page 1 Malaga. Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD Lag (hr) _ 0.0 SHORTCUT METHOD Less than 100 -200 acres & La Time < 7 -8 min) Data Input (boxed is calced) Concentration Point NA Soil Group (Sheet 11/ pp 78) . B Area Designation NA Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres). 29 0.05 sqmi Area Precip Corr (E5.8 ( %)) 100.00 L (miles) 1 0.1333333 Total Adjusted Storm = 2.50 Lca (miles) 0.1 Runoff Index (PI E -6.1) ' 1 56 Elev @ Headwater 1 JAMC Condition (I, II, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.51 De el Area Cover (PI 6.3) 1 58% S (fUmile)= 7.5 Const Loss Rate, F (3 -6 hr storm) 1 0.24 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.12 Lag (min) 0.1 _ Low Loss Rate Percent 3 & 6hr : 0.90 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 183695 Cubic Ft Duration 3, 6, 24 3 4.2 JAcre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cult) (cuft) (cuft) 5 1.3 0.39 0.24 0.24 0.15 0.0 0 0 10 1.3 0.39 0.24 0.24 0.15 4.2 1265 1265 15 1.1 0.33 0.24 0.24 0.09 2.5 743 2008 20 1.5 0.45 0.24 0.24 0.21 6.0 1787 3796 25 1.5 0.45 0.24 0.24 0.21 6.0 1787 5583 30 1.8 0.54 0.24 0.24 0.30 8.6 2570 8153 35 1.5 0.45 0.24 0.24 0.21 6.0 1787 9940 _ 40 1.8 0.54 0.24 0.24 0.30 8.6 2570 12510 45 1.8 0.54 0.24 0.24 0.30 8.6 2570 15080 50 1..5 0.45 0.24 0.24 0.21 6.0 1787 16868 55 1.6 0.48 0.24 0.24 0.24 6.8 2048 18916 60 1.8 0.54 0.24 0.24 0.30 8.6 2570 21486 65 2.2 0.66 0.24 0.24 0.42 12.0 3614 25100 70 2.2 0.66 0.24 0.24 0.42 12.0 3614 28714 75 2.2 0.66 0.24 0.24 0.42 12.0 3614 32329 80 2.0 0.60 0.24 0.24 0.36 10.3 3092 35421 85 2.6 0.78 0.24 0.24 0.54 15.5 4658 40079 90 2.7 0.81 0.24 0.24 0.57 16.4 4919 44998 95 2.4 0.72 0.24 0.24 0.48 13.8 4136 49134 100 2.7 0.81 0.24 0.24 0.57 16.4 4919 54053 105 3.3 0.99 0.24 0.24 0.75 21.6 6485 60539 110 3.1 0.93 0.24 0.24 0.69 1 19.9 5963 66502 115 2.9 0.87 0.24 0.24 0.63 18.1 5441 71943 120 3.0 0.90 0.24 0.24 0.66 19.0 5702 77645 125 3.1 0.93 0.24 0.24 0.69 19.9 5963 83608 130 4.2 1.26 0.24 0.24 1.02 29.4 8834 92443 135 5.0 1.50 0.24 0.24 1.26 36.4 10922 103365 140 3.5 1.05 0.24 0.24 0.81 23.4 7007 110372 145 6:8 2.04 0.24 0.24 1.80 52.1 15620 125992 150 7.3 2.19 014 0.24 1.95 56.4 16925 142917 155 8.2 2.46 0.24 0.24 2.22 64.2 19274 162191 160 5.9 1.77 0.24 0.24 1.53 44.2 13271 175463 165 2.0 0.60 0.24 0.24 0.36 10.3 3092 178555 170 1.8 0.54 0.24 0.24 0.30 8.6 2570 181125 175 1.8 0.54 0.24 0.24 0.30 8.6 2570 183695 180 0.6 0.18 0.24 0.16 0.02 0.5 0 183695 0 0.0 1 0.00 1 0.24 0.00 0.00 0.0 0 183695 Page 1 Malaga 10_3_07 Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I 1 Lag (hr) _ 0.0 SHORTCUT METHOD Less than 100 -200 acres & La Time < 7 -8 min) Data Input (boxed is calced) Concentration Point NA JSoil Group (Sheet 11/ pp 78) C Area Designation NA Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres) 25.8 0.04 sqmi Area Precip Corr (E5.8 ( %)) 1 100.00 L (miles) 1 0.1333333 Total Adjusted Storm = 1 2.50 Lca (miles) 0.1 Runoff Index (PI E -6.1) 69 Elev @ Headwater 1 AMC Condition (I, II, or III (Sheet E -8)) I 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.37. H =� 1 Devel Area Cover (PI 6.3) 55% S (fUmile) =J 7.5 1 Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) 0.1 Low Loss Rate Percent 3 & 6hr : 0.90 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 178484 Cubic Ft Duration 3, 6, 24 3 4.1 Acre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cult) (cult) (cuft) 5 1.3 0.39 0.19 0.19 0.20 0.0 0 0 10 1.3 0.39 0.19 0.19 0.20 5.2 1568 1568 15 1.1 0.33 0.19 0.19 0.14 3.7 1104 2673 20 1.5 0.45 0.19 0.19 0.26 6.8 2033 4705 25 1.5 0.45 0.19 0.19 0.26 6.8 2033 6738 30 1.8 0.54 0.19 0.19 0.35 9.1 2729 9468 35 1.5 0.45 0.19 0.19 0.26 6.8 2033 11501 40 1.8 0.54 0.19 0.19 0.35 9.1 2729 14230 45 1.8 0.54 0.19 0.19 0.35 9.1 2729 16960 50 1.5 0.45 0.19 0.19 0.26 6.8 2033 18992 55 1.6 0.48 0.19 0.19 0.29 7.6 2265 21258 60 1.8 0.54 0.19 0.19 0.35 9.1 2729 23987 65 2.2 0.66 0.19 0.19 0.47 12.2 3658 27645 70 2.2 0.66 0.19 0.19 0.47 12.2 3658 31304 75 2.2 0.66 0.19 .0.19 0.47 12.2 3658 34962 80 2.0 0.60 0.19 0.19 0.41 10.6 3194 38156 85 2.6 0.78 0.19 0.19 0.59 15.3 4587 42743 90 2.7 0.81 0.19 0.19 0.62 16.1 4819 47562 95 2.4 0.72 0.19 0.19 0.53 13.7 4123 51685 100 2.7 0.81 0.19 0.19 0.62 16.1 4819 56504 105 3.3 0.99 0.19 0.19 0.80 20.7 6212 62716 110 3.1 0.93 0.19 0.19 0.74 19.2. 5748 68465 115 2.9 0.87 0.19 0.19 0.68 17.6 5284 73748 120 3.0 0.90 0.19 0.19 0.71 18.4 5516 79264 125 3.1 0.93 0.19 0.19 0.74 19.2 5748 85012 130 4.2 1.26 0.19 0.19 1.07 27.7 8302 93314 135 5.0 1.50 0.19 0.19 1.31 33.9 10160 103474 140 3.5 1.05 0.19 0.19 0.86 .22.3 6677 110151 145 6.8 2.04 0.19 0.19 1.85 47.8 14339 124491 150 7.3 2.19 0.19 0.19 2.00 51.7 15500 139991 155 8.2 2.46 0.19 0.19 2.27 58.6 17590 157581 160 5.9 1.77 0.19 0.19 1.58 40.8 12250 169831 165 2.0 0.60 0.19 0.19 0.41 10.6 3194 173025 170 1.8 0.54 0.19 0.19 0.35 9.1 2729 175754 175 1.8 0.54 0.19 0.19 0.35 9.1 2729 178484 180 0.6 0.18 0.19 0.16 0.02 0.5 0 178484 0 0.0 0.00 0.19 0.00 0.00 0.0 0 178484 Page 1 Malaga (3) Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I I Lag (hr) _ 0.0 SHORTCUT METHOD Less than 100 -200 acres & Lag Time < 7 -8 min) Data Input (boxed is calced) Concentration Point NA Soil Group (Sheet 11/ pp 78) B Area Designation NA Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres) 29 0.05 sqmi Area Precip Corr (E5.8 ( %)) 100.00 L (miles) 0.1333333 Total Adjusted Storm = 2.50 Lca (miles) 0.1 Runoff Index (PI E -6.1) 1 56 Elev @ Headwater 1 JAMC Condition (I, II, or III (Sheet E -8)) _ 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.51 H =� 1 Devel Area Cover (PI 6.3) 1 58% S (fUmile) =� 7.5 Const Loss Rate, F (3 -6 hr storm) 1 0.24 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F1 0.12 Lag (min) I 1 0.1 Low Loss Rate Percent 3 & 6hr : 1 0.90 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 183695 lCubic Ft Duration 3, 6, 24 3 4.2 jAcre - Ft Unit Time Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) ( %) (in /hr) (in /hr) (cfs) (cult) (cult) (cult) 5 1.3 0.39 0.24 0.24 0.15 0.0 0 0 10 1.3 0.39 0.24 0.24 0.15 4.2 1265 1265 15 1.1 0.33 0.24 0.24 0.09 2.5 743 2008 20 1.5 0.45 0.24 0.24 0.21 6.0 1787 3796 25 1.5 0.45 0.24 0.24 0.21 6.0 1787 5583 30 1.8 0.54 0.24 0.24 0.30 8.6 2570 8153 35 1.5 0.45 0.24 0.24 0.21 6.0 1787 9940 _ 40 1.8 0.54 0.24 0.24 0.30 8.6 2570 12510 45 1.8 0.54 0.24 0.24 0.30 8.6 2570 15080 50 1.5 0.45 0.24 0.24 0.21 6.0 1787 16868 55 1.6 0.48 0.24 0.24 0.24 6.8 2048 18916 _ 60 1.8 0.54 0.24 0.24 0.30 8.6 2570 21486 65 2.2 0.66 0.24 0.24 0.42 12.0 3614 25100 70 2.2 0.66 0.24 0.24 0.42 12.0 3614 28714 75 2.2 0.66 0.24 0.24 0.42 12.0 3614 32329 80 2.0 0.60 0.24 0.24 0.36 10.3 3092 35421 85 2.6 0.78 0.24 0.24 0.54 15.5 4658 40079 90 2.7 0.81 0.24 0.24 0.57 16.4 4919 44998 95 2.4 0.72 0.24 0.24 0.48 13.8 4136 49134 100 2.7 0.81 0.24 0.24 0.57 16.4 4919 54053 105 3.3 0.99 0.24 0.24 0.75 21.6 6485 60539 110 3.1 0.93 0.24 0.24 0.69 19.9 5963 66502 115 2.9 0.87 0.24 0.24 0.63 18.1 5441 71943 120 370 0.90 0.24 0.24 0.66 19.0 5702 77645 125 3.1 0.93 0.24 0.24 0.69 19.9 5963 83608 130 4.2 1.26 0.24 0.24 1.02 29.4 8834 92443 135 5.0 1.50 0.24 0.24 1.26 36.4 10922 103365 140 3.5 1.05 0.24 0.24 0.81 23.4 7007 110372 145 6.8 2.04 0.24 0.24 1.80 52.1 15620 125992 150 7.3 2.19 0.24 0.24 1.95. 56.4 16925 142917 155 8.2 2.46 0.24 0.24 2.22 64.2 19274 162191 160 5.9 1.77 0.24 0.24 1.53 44.2 13271 175463 165 2.0 0.60 0.24 0.24 0.36 10.3 3092 178555 170 1.8 0.54 0.24. 0.24 0.30 8.6 2570 181125 175 1 1.8 0.54 0.24 0.24 0.30 8.6 2570 183695 180 0.6 0.18 0.24 0.16 0.02 0.5 0 183695 0 0.0 0.00 0.24 0.00 0.00 0.0 1 0 1 183695 Malaga 10_3_07 Riverside County Hydrology Manual Calculation of SYNTHETIC UNIT HYDROGRAPH METHOD I I Lag (hr) _ 0.0 SHORTCUT METHOD Less than 100 -200 acres & Lag Time < 7 -8 min) Data Input (boxed is calced) Concentration Point NA Soil Group (Sheet 11/ pp 78) C Area Designation NA Precipitation Rate (PI E5.1 -5.6) 2.5 Area (acres) 25.8 0.04 sqmi Area Precip Corr (E5.8 ( %)) 1 100.00 L (miles) 1 0.1333333 1 Total Adjusted Storm = 2.50 Lca (miles) 0.1 1 Runoff Index (PI E -6.1) 1 69 Elev @ Headwater 1 AMC Condition (I, II, or III (Sheet E -8)) 2 Elev @ Concentration Point 0 Infiltr Rate for Pery Areas (PI E -6.2) Fp 0.37 H =j 1 Devel Area Cover (PI 6.3) 1 55% S (ft/mile) =l 7.5 Const Loss Rate, F (3 -6 hr storm) 0.19 n (Ave Mann, Plate E.3) 0.0015 Fm, Min Low Loss 50 -75% of F 0.09 Lag (min) I 1 0.1 Low Loss Rate Percent 3 & 6hr : 0.90 Storm Frequency (10, 25, 100) 100 Results La Quinta Zone (1 to 6) 6 178484 lCubic Ft Duration 3, 6, 24 3 4.1 1 Acre - Ft Unit Time F Pattern Storm Loss Rates Effective Flood Period Percent Rain Max Used Rate Rain Hydrograph Volume Sum Vol Basin Infil (min) (%) (in /hr) (in /hr) (cfs) (cult) (cult) (cult) 5 1.3 0.39 0.19 0.19 0.20 0.0 0 0 10 1.3 0.39 0.19 0.19 0.20 5.2 1568 1568 15 1.1 0.33 0.19 0.19 0.14 3.7 1104 2673 20 1.5 0.45 0.19 0.19 0.26 6.8 2033 4705 25 1.5 0.45 0.19 0.19 0.26 6.8 2033 6738 30 1.8 0.54 0.19 0.19 0.35 9.1 2729 9468 35 1.5 0.45 0.19 0.19 0.26 6.8 2033 11501 _ 40 1.8 0.54 0.19 0.19 0.35 9.1 2729 14230 45 1.8 0.54 0.19 0.19 0.35 9.1 2729 16960 50 1.5 0.45 0.19 0.19 0.26 6.8 2033 18992 55 1.6 0.48 0.19 0.19 0.29 7.6 2265 21258 60 1.8 0.54 0.19 0.19 0.35 9.1 2729 23987 65 2.2 0.66 0.19 0.19 0.47 12.2 3658 27645 70 2.2 0.66 0.19 0.19 ` 0.47 12.2 3658 31304 75 2.2 0.66 0.19 0.19 0.47 12.2 3658 34962 80 2.0 0.60 0.19 0.19 0.41 10.6 3194 38156 85 2.6 0.78 0.19 0.19 0.59 15.3 4587 42743 90 2.7 0.81 0.19 0.19 0.62 16.1 4819 47562 95 2.4 0.72 0.19 0.19 0.53 13.7 4123 51685 100 2.7 0.81 0.19 009 0.62 16.1 4819 56504 105 3.3 0.99 0.19 0.19 0.80 20.7, 6212 62716 110 3.1 0.93 0.19 0.19 0.74 19.2 5748 68465 115 2.9 0.87 0.19 0.19 0.68 17.6 5284 73748 120 3.0 0.90 0.19 0.19 0.71 18.4 5516 79264 125 3.1 0.93 0.19 0.19 0.74 1 19.2 5748 85012 130 4.2 1.26. 0.19 0.19 1.07 27.7 8302 93314 135 5.0 1.50 0.19 0.19 1.31 33.9 10160 103474 140 3.5 1.05 0.19 0.19 0.86 22.3 6677 110151 145. 6.8 2.04 0.19 0.19 1.85 47.8 14339 124491 150 7.3 2.19 0.19 0.19 2.00 51.7 15500 139991 155 8.2 2.46 0.19 0.19 2.27 58.6 17590 157581 160 5.9 1.77 0.19 0.19 1.58 1 40.8 12250 169831 165 2.0 0.60 0.19 0.19 0.41 10.6 3194 173025 170 1.8 0.54 0.19 0.19 0.35 9.1 2729 175754 175 1.8 0.54 0.19 0.19 0.35 9.1 2729 178484 180 0.6 0.18 0.19 0.16 0.02 0.5 1 0 178484 0 0.0 0.00 0.19 0.00 0.00 0.0 1 0 178484 Page 1