2 Precipitation and Evaporation

Transcription

1 Zone 7 Water Agency 2.1 Program Description 2 Precipitation and Evaporation Program Description This section describes Zone 7's Climatological Monitoring Program which tracks rainfall and evaporation in the Valley. Zone 7 uses a network of climatological stations to provide high quality data for long-term studies, basin recharge calculations, and water management decisions. The Zone 7 Climatological Monitoring Program network consists of seven rainfall stations, two pan evaporation stations, and one California Irrigation Management Information System (CIMIS) station located within the Upper Alameda Creek Watershed. The boundary of the watershed, the location of the climatological stations, and isohyets (the lines of equal annual average rainfall) are shown in Figure 2-1. Table 2-2 lists the stations and provides basic station information including the station ID, name, location, and mean annual precipitation or evapotranspiration (ETo). There are two basic types of rainfall stations used in Zone 7 s climatological monitoring program: daily record stations and recorder stations. A daily record station consists of a rain gauge at which, once-a-day, the observer measures and records the depth of rain that has fallen during the preceding 24 hours. A recorder station, which provides rainfall intensity for periods of less than 24 hours as well as daily totals, consists of a computerized-tipping-bucket rain gauge and a data recorder. These semi-continuous-reading rain gauges generally provide rainfall totals on a 15-minute frequency. Zone 7 s climatological monitoring program also contains both reference evapotranspiration and pan evaporation stations to determine water transfer to the atmosphere. Station 191 (CIMIS) is a reference evapotranspiration station, which estimates the ETo value of the water used by a wellwatered, full-cover grass surface, whereas the pan evaporation stations at Lake Del Valle (LDV) and Livermore Water Reclamation Plant (LWRP) measure evaporation directly. LDV and LWRP pan evaporation data is converted to ETo using a conversion factor (ETo=Pan Evap x ). Zone 7 uses ETo to calculate evaporation from the mining ponds as well as in its applied water recharge model. The CIMIS Station s ETo is also used as part of Zone 7 s Water Conservation program to help regulate weather-based irrigation controllers (WBIC or SMART Controllers) Program Changes for the 2016 WY In the 2016 WY, four new rainfall stations were incorporated into Zone 7 s rainfall program. Three of these new stations, ALTC (Altamont Creek), AMNL (Arroyo Mocho Near Livermore), and AMP (Arroyo Mocho Pleasanton) are 15-minute recorder stations that have been added to Annual Report for the Groundwater Management Program 2016 WY July 2017

2 Zone 7 Water Agency 2 Precipitation and Evaporation existing stream flow gauging stations. The fourth new station, NC (North Canyons) is also a 15- minute recorder station and is located at Zone 7 s main office in Livermore. 2.2 Results for the 2016 WY In the 2016 WY (October 1, 2015 through September 30, 2016), total rainfall in the Valley was 116% of the average water year. Rainfall totals from individual stations ranged from inches (103% of average) at Station 24 (Patterson Pass Water Treatment Plant) to inches (113% of average) at Station 170 (Parkside). The rainfall hydrograph for Station 15E (Figure 2-3), presents data for that station for the 2016 WY, along with the driest water year (1977), the average water year (calculated), the wettest year (1983), and the previous water year for comparison. The monthly precipitation totals for each of Zone 7 s rainfall monitoring stations for the 2016 WY are shown in Table 2-4. Table 2-5 shows historical monthly data from Station 15E in Livermore, the station with the longest historical record ( ). In the 2016 WY, Station 15E received 106% of the historical record annual average. ETo for the 2016 WY was inches (108% of normal) at the Lake Del Valle Station, (103% of normal) inches at the CIMIS station, and inches (88% of normal) at the LWRP Station; however, the LWRP data has a history of being somewhat unreliable (e.g., missing data or results not consistent with other stations). Table 2-6 provides the monthly ETo for each of the three monitoring stations during the 2016 WY, and Table 2-7 shows monthly pan evaporation measured at Lake Del Valle (Station LDV-EV) with data going back to the 1969 WY. Annual Report for the Groundwater Management Program 2016 WY 2-2 July 2017

3 Legend Climatological Stations 2016 Miles Measures Rainfall Rainfall and Evaporation Rainfall and Evapotranspiration (CIMIS) Isohytes of Average Annual Rainfall (in)(alameda Cnty 2011) Zone 7 Service Area Main Basin Management Area Fringe Management Area Upland Management Area ALTC 15E LWRP LDV AMP 24 NC AMNL Figure 2-1 Climatological Monitoring Stations with Average Rainfall (in) 19 E:\MONITOR\PR\2016WY\AnnualReport2016\Fig02-01-MapCMStations2016.mxd Date: Jul 11, Service Layer Credits: Sources: Esri, HERE, DeLorme, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, 28 14

4 SITE TABLE 2-2 TABLE OF CLIMATOLOGICAL STATIONS 2016 WATER YEAR (Oct 2015 to Sep 2016) COMPUTER SITE ID STATION NAME LOCATION OBSERVER 15E CM_STA 15E NOAA Livermore 17 CM_STA 17 Del Valle Plant PRECIPITATION NETWORK Wellingham Drive, Livermore 601 East Vallecitos Rd, Livermore ELEV- ATION STATION ESTABLISHED 15 MIN RECORD MEAN ANNUAL (IN) MR. RON HAFNER ZONE to Present CM_STA 24 Patterson Plant Patterson Pass Rd, Livermore ZONE to Present CM_STA 34 Mocho Wellfield Santa Rita Rd, Pleasanton ZONE to CM_STA 44 Mt Hamilton 101 CM_STA 101 Tassajara Lick Observatory, Mt. Hamilton Camino Tassajara Rd, Danville LICK OBSERVATORY MRS. JOAN HANSEN CM_STA 170 Parkside Parkside Drive, Pleasanton ZONE to CM_STA 191 CIMIS Station ALTC CM_STA ALTC Altamont Creek AMNL CM_STA AMNL Arroyo Mocho Near Liv AMP CM_STA AMP Arroyo Mocho Pleas NC CM_STA NC North Canyons Office Alameda County Fairgrounds, Pleasanton at ALTC_BD surface water station at AMNL surface water station At AMP Surface Water Station Zone 7's North Canyons building DWR to Present ZONE to Present ZONE to Present ZONE to Present ZONE to Present EVAPORATION NETWORK SITE COMPUTER SITE ID STATION NAME LOCATION OBSERVER ELEV- ATION STATION ESTABLISHED 15 MIN RECORD MEAN ANNUAL (IN) LDV CM_STA LDV-EV Lake Del Valle Arroyo Rd, Livermore DWR LWRP CM_STA LWRP-EV Livermore Water Reclamation Plant 191 CM_STA 191-ETO CIMIS Station Jack London Drive, Livermore Alameda County Fairgrounds, Pleasanton LWRP DWR * Stations LDV and LWRP record evaporation using pan evaporation equipment. ETo is derived using : ETo= Pan Evaporation x E:\MONITOR\PR\2016WY\Climatological2016.xlsm Table 2-2

5 9/30 10/31 11/30 12/31 1/31 2/28 3/31 4/30 5/31 6/30 7/31 8/31 9/30 FIGURE 2-3 ZONE 7 WATER AGENCY GRAPH OF LIVERMORE RAINFALL (DAILY RECORD FROM STATION 15E NOAA) 35 Total Annual Rainfall % Avg Probability of Exceedence Wettest (1983 WY) % 1% WY % 3% Inches of Rain WY Average Rainfall 2015 WY % 36% % 41% % 53% 10 5 Driest (1977 WY) % 98% 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 2016 Water Year Monthly (inches) % Monthly Avg 3% 152% 96% 137% 28% 152% 199% 45% 0% 0% 0% 0% YTD (inches) % Average YTD 3% 107% 101% 114% 94% 104% 112% 109% 108% 108% 108% 106% % Annual Avg 0% 17% 35% 62% 67% 90% 105% 106% 106% 106% 106% 106% E:\MONITOR\PR\2016WY\ST15eGRF16.xlsx Figure 2-3

6 TABLE 2-4 MONTHLY PRECIPITATION DATA 2016 WATER YEAR (Oct 2015 to Sep 2016) MONTHLY PRECIPITATION IN INCHES MONITORING STATION 2016 % Historic Network Network CM_STA 15E CM_STA 17 CM_STA 24 CM_STA 34 CM_STA 44 CM_STA 101 CM_STA 170 CM_STA 191 CM_STA ALTC CM_STA AMNL CM_STA AMP CM_STA NC Average Average 15E ALTC AMNL AMP NC OCT % NOV % DEC % JAN % FEB % MAR % APR % MAY % JUN % JUL % AUG % SEP % TOTAL * % AVG 106% 109% 103% 108% 144% 108% 113% 124% 100% 100% ** 100% 116% *Average Rainfall for Station 191 calculated from data collected at the station from 2004 to present. **Insufficient data for average calculation DISTRIBUTION OF DAILY PRECIPITATION Number of days with rainfall greater than reference MONITORING STATION 2016 Rainfall Network (inches) 15E ALTC AMNL AMP NC Average >Trace > > > > E:\MONITOR\PR\2016WY\Climatological2016.xlsm 8/2/2017 Table 2-4

7 TABLE 2-5 HISTORICAL MONTHLY PRECIPITATION MONITORING STATION 15E, LIVERMORE (INCHES) 1871 to 2016 WATER YEARS TOTAL TOTAL % AVERAGE Water Year OCTWY NOVWY DECWY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT-SEP JULY-JUNE OCT-SEP 1871 NA NA NA NA NA NA % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % Water Year = October to September E:\MONITOR\PR\2016WY\Climatological2016.xlsm Table 2-5 Page 1 of 2

8 TABLE 2-5 HISTORICAL MONTHLY PRECIPITATION MONITORING STATION 15E, LIVERMORE (INCHES) 1871 to 2016 WATER YEARS TOTAL TOTAL % AVERAGE Water Year OCTWY NOVWY DECWY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT-SEP JULY-JUNE OCT-SEP % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % MAXIMUM % MINIMUM % MEAN % Water Year = October to September E:\MONITOR\PR\2016WY\Climatological2016.xlsm Table 2-5 Page 2 of 2

9 TABLE 2-6 MONTHLY EVAPOTRANSPITATION (ETo) DATA 2016 WATER YEAR (Oct 2015 to Sep 2016) MONTHLY REFERENCE EVAPOTRANSPIRATION (Eto) (inches) 2016 % Historic Network Network LDV LWRP 191 Average Average OCT % NOV % DEC % JAN % FEB % MAR % APR % MAY % JUN % JUL % AUG % SEP % TOTAL % AVG 108% 88% 103% 100% 1) ETo values for LDV and LWRP were approximated using : ETo= Pan Evaporation x E:\MONITOR\PR\2016WY\Climatological2016.xlsm Table 2-6

10 TABLE 2-7 HISTORICAL MONTHLY PAN EVAPORATION MONITORING STATION LAKE DEL VALLE, LIVERMORE (INCHES) TOTAL TOTAL % AVERAGE Water Year OCTWY NOVWY DECWY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT-SEP JULY-JUNE OCT-SEP NA 103% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % MAXIMUM % MINIMUM % MEAN % ETo can be approximated using: ETo= Pan Evaporation x Water Year = October to September E:\MONITOR\PR\2016WY\Climatological2016.xlsm Table 2-7