Methodology

Methodology for the Headwaters to Groundwater Project was based upon precipitation -- how much, and where does the water go once it reaches the surface?

Precipitation falls to the surface in a predictable, but spatially variable pattern. Surface characteristics affect the behavior of the rain as it hits the surface. For example, porous soil absorbs water, while concrete causes it to flow down slope. Both the slope and aspect (which way it faces) may alter the water flow speed and path. Water flow which bypasses opportunities for recharge has a negative environmental impact on the thirsty SFB aquifer.

The Headwaters to Groundwater Project reviewed the study area's topography to determine various opportunities to intervene and change the water flow outcome to improve the natural utilization of the limited Southern California precipitation

Recharge Suitability Analysis (RSA)

The Project team selected a geographic information system (GIS) tool for analyzing the focus area for existing and potential groundwater recharge zones. GIS specialists from California State University Northridge and the University of Southern California participated in the analysis effort. A three-part hydrological study and analysis identifying existing recharge areas and areas with potential recharge capacity.

Project - Part I - Data collection, existing data review on geology, hydrology, vegetation, land use and watershed plans. A pre-data list for conducting a RSA helped guide the direction for collecting subsequent data. A geodatabase for storing geographic and spatial data was created and assimilated into existing watershed efforts and helped identify information gaps.

Project - Part II - Monitor the focus area to understand stream water quality health and determine where stream pollutants were affecting Los Angeles River groundwater. Stream condition was measured by riparian surveys, including stream walks, wetland mapping and stream survey. Wetland mapping followed the National Wetland Inventory protocols, and stream survey was guided by the Natural Channel Design Stream Survey Protocols.

Monthly water sampling was done on 20 creeks in the focus area to analyze water chemistry and on-site measurable water properties. Factors in site selection included presence of human impact upstream, access ease and safety, and flow quantity.

Project - Part III - A suitability analysis identifying suitable areas to recharge native waters before it becomes urban runoff with associated pollutant loads. The two-part analysis included Direct Infiltration Analysis and Flow Accumulation Analysis.

Download the complete Recharge Suitability Analysis (RSA) pdf. 7.5MB....