1. Systems and Components – A Process for Developing the Total Water Budget
Handbook for Water Budget Development - With or Without Models CWEMF 2019 Annual Meeting
April 22, 2019
PRESENTER
Todd Hillaire (DWR)
COLLABORATORS
Abdul Khan (DWR)
Paul Shipman (DWR)
Saquib Najmus (Woodard & Curran)
Frank Qian (Woodard & Curran)

2. Presentation Outline Total water budget and water budget zone
Systems and components
Water Budget Accounting Template
Handbook organization using systems and components
Water budget components – definitions, methods, and data

3. The Total Water Budget and Water Budget Zone
The total water budget is a comprehensive accounting of all inflows to and outflows from the three interrelated and interacting systems in a water budget zone:
Land system.
Surface water system.
Groundwater system.
A water budget zone represents any user-defined water management area, such as a watershed, groundwater basin, water district, groundwater sustainability agency (GSA), or other geographical area.

4. Total Water Budget Schematic
Land System
Surface Water System
Groundwater System

5. Water Accounting Template – The Total Water Budget

6. Systems and Components
Systems organize a highly complex water budget schematic into manageable units of analysis
Represent all inflows, all outflows, and change in storage for each system
Check for mass balance error at the system level
Systems illustrate flow interactions not captured in a total water budget
Inflows and outflows across a system boundary
Systems illustrate the internal water flow associated with management.
Applied Water - identifies how much water is used for Ag, Urban, and Managed Wetlands but is only an internal flow component but is not a mass balance term
Reuse and recycled water – identifies water management actions but is not a mass balance term

7. Handbook Organization
The Handbook organizes components by system – Land, Surface Water, and Groundwater – for ease of analysis.
The Handbook provides context, outlines a range of methods, identifies potential data sources, and provides examples by system
Individual component calculations are key for modeling and non-modeling approaches.
Models need input based on component calculations, such as urban applied water.
The Handbook systematically organizes systems and components to roll-up water balances.

8. Land System - Overview
The land system is the portion of the water budget zone that includes the land surface and the unsaturated zone that extends vertically to the top of the groundwater system (i.e., water table).

9. Land System – Organization by Water Use Sectors
Managed land uses
Agricultural lands
Urban areas, including large landscape and industrial
Managed wetlands
Native and riparian lands

10. Land System – Components
Precipitation
Evapotranspiration
Applied Water – agriculture, urban, managed wetlands
Surface Water Delivery
Groundwater Extraction
Applied Water Reuse And Recycled Water
Recycled Water Export
Runoff
Return Flow
Change In Land System Storage
Note
Recharge of Applied Water & Precipitation included in Groundwater System

11. Water Accounting Template – Land System

12. Land System Water Budget – Urban Example
Inflows = Precipitation + Surface Water Delivery + Groundwater Extraction + Stored Water Extraction
Outflows = ET of Precipitation + Recharge of Precipitation + Runoff from Precipitation + ETAW (Landscape) + Recharge of Applied Water + Return Flow of Outdoor Water Use + Return Flow of Indoor Water Use + Managed Aquifer Recharge + Recycled Water Export
Change in Land System Storage for Urban Areas = Inflows – Outflows

13. Urban Applied Water
Account for all components of water routing

14. Agricultural Applied Water
Account for all components of water routing

15. Agricultural Applied Water
Account for the sources of supply
Account for the components of applied water
Similar for managed wetlands – accounts for habitat vegetation and ponding

16. Estimating Agricultural Applied Water Using the Handbook – An Example Process
Defined – “Volume of water applied on agricultural land from all sources of water to meet on-farm crop irrigation requirements.”
Context – it is a function of the water management goals and methods used to irrigate a crop and may be unique to each area.
Calculation –
Agricultural Applied Water = (Crop ET – Effective Precipitation) / Irrigation Efficiency
Applied water adjustments - irrigation efficiency, on-farm managed aquifer recharge, shallow groundwater uptake.

17. Methods for Estimating Agricultural Applied Water
Obtain available water delivery data.
Use available technical reports and existing numerical models.
Estimate applied water volumes (2 approaches)
Water-duty based approach
Crop ET approach
Includes practical steps added to estimate supply by source, recharge, return flow in relation to applied water

18. Crop ET Approach – Steps to Estimate Applied Water and More
Calculate Crop ET Requirements
Calculate Precipitation Volume for the Agricultural Area
Calculate Runoff Volume
Calculate ET of Precipitation
Calculate ET of Applied Water
Estimate Applied Water using Irrigation Efficiency
Calculate Volume of Applied Water
Calculate Volume of Groundwater Extraction
Calculate Volume of Applied Water Reuse
Calculate Volume of Surface Water Delivery
Calculate Volume of Irrigation Recharge
Calculate Volume of Irrigation Return Flow
Practical steps added to estimate supply by source, recharge, return flow

19. Change in Land System Storage
“Net change in the volume of water stored within the land system, which includes ponded water on the land surface (not including streams, lakes, and conveyance facilities) and soil moisture within the unsaturated zone, which includes the root zone.”
Inflow to the Land System – Outflow from the Land System =
Change in Unsaturated Zone Storage + Change in Ponded Water + Change in Rootzone Storage
Methods
Use published reports and numerical models
Estimate using inflow and outflow balance
Use ponded area, depth, and duration to estimate change in ponded water storage
Use water use models to determine change in soil moisture storage
Estimate change in unsaturated zone storage as a water balance
Assessing mass balance error - unrealistic given lack of direct measurements

20. Surface Water System - Overview
The surface water system is the portion of the water budget zone that includes rivers and streams, conveyance facilities and diversion ditches, and lakes and reservoirs that are part of the water supply system for meeting agricultural, urban, and managed wetlands applied water demands.

21. Surface Water System Organization - Overview
Stream Inflow And Outflow
Surface Water Diversion
Stream Evaporation
Conveyance Evaporation
Conveyance Seepage
Imported Water & Surface Water Export
Stream-Lake Interaction
Lake Evaporation
Change In Surface Water Storage
Note
Stream-Groundwater Interaction included in Groundwater System

22. Water Accounting Template – Surface Water System

23. Stream Inflow And Outflow – Estimating the Components
Methods
Obtain available streamflow data.
Estimate from available streamflow data.
Estimate streamflow using drainage area ratio method.
Estimate streamflow using rainfall-runoff model
Data Sources in component subsection
USGS Surface-Water Data for California
USGS publications: Water-Resources Investigations Reports , Scientific Investigations Reports
DWR California Data Exchange Center (CDEC)
DWR Water Data Library
Local agency records, including flood control districts or entities managing storm water
SWRCB Irrigated Lands Regulatory Program
Input/output files of numerical models (e.g. rainfall-runoff model).
Data Resources Directory

24. Groundwater System - Overview
The groundwater system is the portion of the water budget zone that extends vertically from the base of the unsaturated zone (water table) to the bottom of the basin within the water budget zone; it can include one or more principal aquifers and represents the physical extent of the water budget zone used to quantify the volume of groundwater stored.

25. Water Accounting Template – Groundwater System

26. Groundwater System - Components
Recharge Of Applied Water And Precipitation
Subsurface Inflow And Outflow
Stream-groundwater Interaction
Lake-groundwater Interaction
Managed Aquifer Recharge
Stored Water Extraction
Groundwater Export
Stored Water Export
Change In Groundwater Storage
Water Release Caused By Land Subsidence

27. Defining Recharge and Store Water Terms
Recharge Of Applied Water And Precipitation focuses on the term “Recharge” instead of “Deep Percolation” to better define destination of water
Managed Aquifer Recharge is part of defined recharge and water banking programs through spreading basins, injection wells, and other means.
Stored Water Extraction – groundwater pumped from the underlying aquifer(s) through a defined recharge and extraction program for use within the water budget zone.
Stored Water Export - groundwater pumped from the underlying aquifer(s) through a defined recharge and extraction program for use outside the water budget zone.

28. Change In Groundwater Storage
“Net change in the volume of groundwater stored within the underlying aquifer of the water budget zone.”
Change in Groundwater Storage = Inflow to Aquifer (Recharge) – Outflow from Aquifer (Discharge)
Can estimated using direct measurements (groundwater levels) or using indirect measurements (remote sensing) coupled with modeling tools
Evaluate mass balance error:
Mass Balance Error = Inflow to Aquifer – Outflow from Aquifer – Change in Groundwater Storage (measured)

29. Water Release Caused By Land Subsidence
“Volume of water released to an aquifer on a one-time basis as a result of land subsidence, which is caused by the inelastic consolidation of porous fine-grained material.”
Methods:
Obtain available technical reports and modeling studies.
Estimate using model results and groundwater level data.

30. Key Takeaways The Handbook provides a systematic process for:
Estimating water budget components
Aggregating components for system and total water budget balances
Estimating change in storage for each system
Evaluating mass balance error
Systems help to organize water budget development and provide water budget checks
Handbook organizes systems and components to promote a sequential pathway for water budget development
See “Case Study: Non-Modeling Approach” presentation
Handbook provides component definitions, context, methods, data sources (including the Data Resources Directory), and examples

31. Questions?