04_PWS_Aerial_Snow_Survey_11072019.pdf

PERFORMANCE WORK STATEMENT

Aerial Snow Surveys of Upper San Joaquin Basin

1.0 SCOPE

The objective of this contract is to acquire spatial snow depth measurements across the San Joaquin Watershed and be provided accurate spatial estimates of snow water equivalent. These surveys will be acquired through remote sensing, conducted at periodic or strategic intervals, and span across accumulation and ablation phases of a winter season. Measurements must be robust to steep terrain, forested areas, and capture the full variability in snow depth. Data acquisition must be able to respond to changing weather, and data reporting must allow Reclamation to make reservoir management decisions in near real-time. The advances in runoff forecasting made possible by remotely sensed snow surveys create substantial benefits to Friant Division water users and the San Joaquin River Restoration Program and provide broad public benefits such as reduced flood magnitude.

2.0 BACKGROUND

The San Joaquin watershed above Millerton Lake, impounded by Friant Dam which is operated by Reclamation, is a high elevation watershed of California’s Sierra Nevada. On average, 70% of runoff originates from snowpack. Peak runoff is typically in May, but this can vary from April to July. The watershed produces on average 1.8 Million acre-feet of runoff (MAF), yet Millerton Lake can only impound 0.5 MAF. Annual runoff is highly variable, ranging from 0.3 MAF to 4.6 MAF, and appears to be trending toward greater variability. Ground-based snow sensors omit portions of the watershed due to land management regulations, and rugged terrain extending nearly to 14,000’ elevation.

Management of snowmelt runoff has been challenged by limited forecast accuracy and slow reporting times, which results in reservoir management decision by Reclamation, and water management decisions by water users and environmental projects, to stray from optimal. Better runoff forecasting results in optimization of limited reservoir storage capacity and canal conveyance capacity, effectively “building” new storage capacity through better information.

Reclamation has been acquiring this information through an Interagency Agreement with NASA and other methods. NASA had been providing aerial snow survey services through the “Airborne Snow Observatory” research project of CalTech/JPL (a NASA contractor). This NASA effort ended the research phase in 2019 and completed the Technology Transfer process to a private vendor in August of 2019. Adjacent watersheds have participated in the Airborne Snow Observatory project in past years, most notably the Tuolumne watershed since 2013. Reclamation retains responsibility for evaluating the snowpack survey information, estimating runoff from snowpack information, and reservoir management decisions.

The service provider retains responsibility for all aspects of data acquisition, airspace permission, ensuring that flight operations adhere to any applicable DOI Office of Aviation Service requirements, reporting, and transfer of data.

3.0 REFERENCES — The following list of documents are required in the performance of this contract:

Author

Title

Date

Source

Pending Pending Pending Pending

4.0 PERIOD OF PERFORMANCE — January 15, 2020 through October 15, 2020

5.0 TASKS — The contractor shall perform the following tasks:

1. Collect snow depth data and snow water equivalent data (SWE) across the San Joaquin Watershed above Millerton Lake. Surveys will be conducted between January 15, 2020 and July 15, 2020, unless the period is otherwise extended by mutual agreement (extremely wet years may result in snow surveys into September). Reclamation will consult with the contractor and set a 15-day target window to accomplish a complete survey, based upon weather and hydrology, which may require multiple flights across multiple days. This window will be scheduled to start at least 72 hours into the future; the window may be rescheduled or shifted by mutual agreement. Five surveys are anticipated within the period of performance.

2. For each aerial snow survey, provide an electronic report within 72 hours of final flight completion. 72 hours is roughly the time it takes for snowmelt in the upper watershed to reach Millerton Reservoir. Receiving reports later than 72 hours reduces the time that Reclamation has to evacuate water. This results in higher flood release magnitudes and reduced opportunities for groundwater recharge.

3. Coordinate weekly phone meetings between Reclamation and contractor from January 1 through July 1 to consult on survey timing, weather, hydrology, and performance factors

4.0 PERFORMANCE REQUIREMENTS SUMMARY

Task #

Task Description

Performance

Indicator

Performance

Standard

Minimum Acceptable Quality Level

1 Snow Depth data and Snow Water Equivalent data across San Joaquin Watershed

SD and SWE at < 5 meter resolution with a precision of 5 centimeters or better

Coverage of watershed’s snow-covered area

> 95% of snow-covered area has survey data at this requisite resolution and precision

1 Complete survey within 15-day window, which may be scheduled with 72 hours notice

Completion rate 75% of surveys within a given year completed within the window when an uninterrupted span of 72 hours of clear skies over the watershed occurs.

Survey reporting Complete and transmit report within 72 hours if final flight completion

Completion rate 75% of reports completed and transmitted within 72 hours of final flight completion

3 Coordination through weekly phone meetings

Consistency of availability for meetings

Minimum fraction of meetings will be scheduled and conducted

75% of weeks between Jan 1 and July 1 have a meeting scheduled and attended by contractor representative

5.0 DATA AND REPORTS — The contractor shall provide the following data and reports as follows:

Task #

Description

Content

Format

Medium

Delivery

2 Snow survey report

See Task #2 Deliverables below

Electronic file Contractor’s choice

Via FTP or data sharing portal

6.0 DELIVERABLES - The contractor shall submit the following reports in accordance with paragraph 5.0, “DATA AND REPORTS”:

• Snow Survey Report (Task #2) shall include:

a. Brief narrative of survey acquisition and conditions

b. Snow depth by 1000’ elevation band (table: mean, std deviation or percentiles)

c. Snow water equivalent by 1000’ elevation band (table: mean, std deviation or percentiles, total volume)

d. Tabular data broken down by HUC 10 units, broken down by four subwatersheds, and aggregated for entire San Joaquin Watershed above Millerton Lake.

e. 50 meter geoTIFF file of snow depth and snow water equivalent