Grantee Research Project Results
1998 Progress Report: Integrated Urban Watershed Analysis: The Los Angeles Basin and Coastal Environment
EPA Grant Number: R825381Title: Integrated Urban Watershed Analysis: The Los Angeles Basin and Coastal Environment
Investigators: Turco, Richard , Fong, Peggy , Berk, Richard , Ambrose, Richard , Dracup, John A. , Forrester, Graham E , Fovell, Robert G , Venkatesan, M. Indira , Orme, Antony , MacDonald, Glen , Walter, Hartmut , Suffett, Irwin , McWilliams, James , Feddema, Johannes , Stolzenbach, Keith , Raphael, Marilyn , Savage, Melissa , Stenstrom, Michael , Vance, Richard , Friedlander, Sheldon , Trimble, Stanley
Current Investigators: Turco, Richard , Friedlander, Sheldon , Berk, Richard , Ambrose, Richard , Fong, Peggy , Dracup, John A. , Feddema, Johannes , Forrester, Graham E , Fovell, Robert G , MacDonald, Glen , McWilliams, James , Orme, Antony , Raphael, Marilyn , Stenstrom, Michael , Stolzenbach, Keith , Suffett, Irwin , Vance, Richard , Venkatesan, M. Indira , Walter, Hartmut , Trimble, Stanley , Hamner, William M
Institution: University of California - Los Angeles
EPA Project Officer: Packard, Benjamin H
Project Period: December 1, 1996 through November 30, 1999 (Extended to November 30, 2000)
Project Period Covered by this Report: December 1, 1997 through November 30, 1998
Project Amount: $1,200,000
RFA: Water and Watersheds Research (1996) RFA Text | Recipients Lists
Research Category: Watersheds , Water
Objective:
This project seeks to understand the processes that control water availability and quality in a major urban watershed?the Los Angeles Basin in Southern California. The study is based on the coupling of data and models that bear on numerous aspects of the water resource problem, including: regional meteorology and climatology; basin hydrology, vegetation, and land use; anthropogenic water consumption and disposition; runoff sources of sediments, toxics and nutrients; air pollutant transport, transformation, and surface deposition; downstream wetlands ecology and impacts; and coastal water circulation, biogeochemistry, and sediments. The various aspects of the problem are being addressed by members of the scientific team assembled through the recently organized UCLA Institute of the Environment. The effort consists of a broad synthesis of observational data?in situ measurements, remotely sensed data, and local geographical information?and model simulations of material flow, deposition, transformation, and bioassimilation. Both the observational and computational data are being collected within a Geographical Information System (GIS) for analyses and applications. Models are being linked to provide a coupled simulation system for the watershed. Planned applications include: an assessment of sources and distributions of trace metals and other toxins in the Los Angeles watershed and their ecosystem effects; estimation of the contributions of anthropogenic water and waste treatment on the coastal environment; and the contributions of air transport and deposition to the burden of various compounds in different compartments of the watershed.The regional modeling consists of atmospheric, land, and coastal ocean components, which are being coupled to define physically consistent regional-scale factors that influence individual watersheds within the L.A. Basin. A coupled regional model can provide a means for integrating diverse natural and anthropogenic sources of materials within the extended watershed environment, for investigating long-range transport and deposition of pollutants, and for producing forecasts of watershed effects owing to changes in the regional setting, human activities within the basin, and so on. The problem is thus seen as a nesting of scales of influence, from the regional scale (the Los Angeles basin and Southern California Bight), to the watershed scale (a major drainage and its coastal receptor wetland and bay?such as the Ballona Wetlands and Santa Monica Bay), to the scales of local drainages (the Ballona Creek sources and estuary). Local sampling is being used to define properties at the smaller scales, while regional modeling is being applied to describe processes on larger scales. The comprehensive database developed under this project includes: local measurements and time series, historical databases, geological and hydrological data, relevant societal and demographic records, land use information, model simulated data, and remote observations, and offers a resource to other studies aimed at scientific understanding of the watershed, environmental impact assessment, or restoration and mitigation schemes.
Progress Summary:
Significant progress was made in each primary area of research and in coupling various components of the project. The MM5 mesoscale dynamics model was applied to study rainfall events in the L.A. Basin, and calculated precipitation was compared with corresponding rain gauge and streamflow data available in Malibu and other watersheds. The MM5 was utilized with and without data assimilation to contrast the fidelity of the predictions, and it was shown that data assimilation improves the forecasts marginally. Simulated precipitation amounts and distributions were then coupled to a hydrological model (see below), and calculated and observed hydrographs were intercompared, revealing good overall agreement. It was, in addition, demonstrated that meteorological predictions lead to improved stream flow representations than rain gauge data alone. Steps were taken to extend the precipitation simulations to higher spatial resolution. In one approach, higher resolution numerical calculations were carried out with the MM5 and compared with rain gauge and hydrologic data. In a second approach, a wavelet analysis technique was applied to extrapolate the coarse resolution mesoscale model rainfall patterns to much finer scales. At present, radar reflection data are being evaluated as a means of identifying geographically fixed relationships between topographical structures and precipitation features at different scales, information that is needed to apply wavelet theory reliably.The work on dendroclimatology of the L.A. region advanced significantly with the collection of six new tree ring series around the area of interest, including records of up to 1,300 years for the first time. These chronologies extend previous climatological information, which in the past provided only a fragmented geographical picture of historical rainfall and soil. Additional data on streamflows in major watersheds were also collected for correlation studies with the tree ring data corresponding to this century. Correlations with dendrochronologies dating back to the early 1900s were positive, although weak. Nevertheless, these relationships will allow us to estimate precipitation regimes hundreds of years ago, and to identify extreme regional conditions of drought and flood. Such information will be invaluable to regional water resource development and emergency planning for extreme seasonal events.
The hydrological component of the project adopted a version of the TOP model for applications in several L.A. area watersheds. In the important Malibu Creek watershed, detailed information on elevation, land use, vegetation type, and soils were collected from regional agencies and analyzed for accuracy. Other data were compiled for model calibration and validation studies, including streamflow and precipitation measurements. The initial validation runs for Malibu Creek were completed this year. In parallel with the hydrologic modeling, a historical frequency analysis was performed on the streamflow and precipitation data for the Malibu Creek watershed. The hydrologic model was then run separately, and coupled to the regional meteorological model as described above, for comparison to the statistical results. The performance of the coupled simulation system was found to be excellent in the cases investigated.
Several dynamic river models were investigated for their ability to predict time-dependent flow within the Los Angeles River, the major drainage for much of the western and northern Los Angeles regions. Both the DWOPER (Dynamic Wave Operational Model), and FLDWAV model were considered, because they allow fundamental transient flow studies to be carried out, and are readily coupled to mesoscale meteorological models such as the MM5 and surface hydrological models such as TOP. Stream gauge and engineering data were collected for the purpose of testing the DWOPER model along a stretch of the L.A. River. With this model in place, the runoff into the San Pedro Bay can be quantified in conjunction with the meteorological forecasting system, and potential impacts of extreme rainfall conditions indicated by historical tree ring analysis can be assessed.
Air quality simulations are being coupled to the hydrologic and runoff components of the project (also see below). A comprehensive regional air quality model (SMOG) was applied to predict nitrogen (in the form of gaseous and particulate fixed nitrogen compounds) deposition across the L.A. Basin and coastal waters. The geographical and temporal characteristics of the deposition indicate heavy deposition near the headwaters of major drainages in the eastern and northern reaches of the L.A. Basin. Significant deposition is also predicted along the coastal waters, off Santa Monica Bay, for example. The inland deposition pattern is found to correlate with nitrate content measured in runoff from these areas. The present calculations represent the first quantitative estimates of regional scale deposition patterns of air pollutants such as nitrates in the L.A. Basin.
The input of speciated size-differentiated aerosol-borne materials to coastal waters were also directly measured under this project. It was found that the trace metal composition (up to 18 elements) of surface air over coastal waters is strongly correlated with the airborne composition measured inland. Lead and cadmium, however, were found to have possible local sources along the coastal region. Unexpectedly, iron and aluminum abundances were observed to increase dramatically during the early morning hours from 2 to 10 a.m. The data suggest that transport of air from land to sea during the night is a key process controlling coastal deposition of particulate mass. This conclusion is consistent with concurrent air quality modeling, as described above.
The runoff component of the project collected a substantial new database on the trace composition of wetland and coastal waters. Local sources were calibrated in the framework of an existing runoff model using measurements of the composition of streams in the region, particularly those in heavily impacted urbanized watersheds such as the Ballona Creek watershed. The runoff chemistry code is based on GIS and hydrologic analysis techniques. Runoff materials?from lead and other metals, to nutrients, to grease and oil?were also recently measured directly in receptor waters for the first time. The data analysis, which has not been completed, will be connected with the air and surface microlayer measurements (described below) as well as deposition simulations available from the air quality component. The various airborne contributions to runoff chemistry are thus being quantified for the first time.
The wetlands component launched major field studies this year emphasizing the goals of the integrated watershed project. The focus initially narrowed to three groups of estuarine organisms: rooted aquatic plants in salt marshes; algae that occupy the water column and/or the soft substratum of intertidal mudflats; and estuarine fish in the same environments. Among recent results, the growth response of pickleweed, Salicornia virginica, was quantified under conditions of artificial nitrogen and phosphorus fertilization, demonstrating that added nutrients can stimulate growth even in a naturally high nitrogen-enriched ecosystem. These findings imply a major role for urban runoff in the growth dynamics and community metabolism of salt marsh communities along an urbanized coastal zone. Other research documented the extreme degree of eutrophication that can be caused by such highly elevated nitrogen levels, even in the most "natural" estuaries still remaining in southern California.
The fish-related work, which is based on four controlled and replicated growth experiments conducted directly in the field, demonstrated that chemical variations in the ambient water characterizing different regional estuaries can lead to substantial growth variations in two resident fish species. These experiments represent one of only a handful of existing applications of field experimental techniques to study estuarine fish populations anywhere in the world. The observed growth variations are being related to the toxic compounds found in these estuaries, which are being measured through chemical analyses of samples of water, mud, and animal tissue, as well as assorted invertebrate prey. This aspect of the study was carried out in collaboration with the runoff component. Chemical and biological characterization of wetland environments will be used to define the impacts of urbanization and enable the identification of key sources of toxic chemicals and their effects.
The development of a new Regional Ocean Modeling System (ROMS) was essentially completed this year under the watershed project. This model incorporates a nesting of spatial scales from the entire western coast of the United States to the Southern California Bight to Santa Monica Bay. This is the first time such a model has been applied to the western United States coastal zone. Model simulations were compared with a variety of data (currents and circulation, sea surface temperature, sea level height, ocean color, etc.) with encouraging outcomes. To complement the modeling, a number of satellite data sets (including AVHRR, RADARSAT, and SeaWIFS) were utilized to study the Santa Monica Bay mesoscale circulations and surface biological activity in greater detail. To connect new in situ biological measurements undertaken in this project with the recently proven coastal simulation capability, a biogeochemical model has been implemented in ROMS.
In research related to the coastal ocean studies, as well as the air
quality and runoff components of the project, novel measurements of the
microlayer and bulk water concentrations of inorganic and organic constituents
in Santa Monica Bay were conducted over relevant spatial and temporal scales.
Microlayer concentrations under dry meteorological conditions provide an
indication of the quantity of atmospheric deposition (the air measurements being
described above). Preliminary results from the microlayer data indicate that
target constituent concentrations are significantly enhanced in the microlayer
as compared with bulk water, and that the enhancement is greatest near shore and
after a period of offshore winds. These findings implicate atmospheric
deposition from the urban airshed as a significant source of contaminants in
Santa Monica Bay. The microlayer compositional measurements are being correlated
with the aerosol constituency recorded at the same times and places, both to
estimate the relative and absolute rates of deposition of various materials to
the coastal waters and to determine the principal factors that control
microlayer composition along the entire L.A. Basin.
In related work on the sources of trace materials in coastal sediments, a novel analysis of DDT in bottom samples succeeded in separating the contributions due to sewage outflows and to industrial dumping. The sewage source is identified through a close relationship that exists between DDT and another class of stable organic compounds used in detergents such as the linear alkylbenzenes (LABs). Thus, using LABs as a tracer, coastal areas with heavy industrial DDT pollution have been identified. This information is being used to formulate remediation plans for the region.
Future Activities:
To enhance the watershed project, a $750,000 equipment grant was received from the Intel Corporation. The resources are being used to build three interrelated computer laboratories. One is a Regional Environmental Assessment Laboratory (REAL), housed in the Institute of the Environment, that will provide high performance computing facilities for various groups of watershed modelers and data analysts. A second connected laboratory provides an advanced GIS/Remote Sensing facility. A related fully equipped GIS teaching facility is also under development. The latter facility will offer access to watershed and related databases to researchers, students and the public.Journal Articles:
No journal articles submitted with this report: View all 91 publications for this projectSupplemental Keywords:
watershed, groundwater, land, sediment, wetland, estuary, meteorology, waste, hydrology, geology, remote sensing, west, Los Angeles, California., RFA, Scientific Discipline, Water, Geographic Area, Waste, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Water & Watershed, Hydrology, Geochemistry, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Contaminated Sediments, State, Ecological Effects - Environmental Exposure & Risk, Ecological Risk Assessment, Watersheds, aquatic ecosystem, coastal ecosystem, nutrient supply, remote sensing, basin hydrology, ecological exposure, wetlands, coastal watershed, meteorology, sediment, urban watersheds, contaminated sediment, Los Angeles Basin, coastal environments, sediment runoff, aquatic ecosystems, urbanizing watersheds, water quality, biogeochemistry, California (CA), groundwater, land useProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.