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5 NAWQA Cycle II Goals - Understanding
Pages 121-161

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From page 121...
... Conversely, model development and application require understanding. The studies that provide an understanding of contaminant sources and their transport can be viewed as the raw materials for the design and development of water quality models.
From page 122...
... committees, should not be underestimated. Understanding and prediction, embodied in water quality models, are the cornerstones of water resources management for the future.
From page 123...
... Thus, each specific targeted study will be designed and executed by various topical teams composed of one or more planned Cycle II study units, and they will be assisted by a single, nationally responsible HST. These so-called targeted studies will focus on the major factors that govern water quality.
From page 124...
... Understanding contaminant sources and contaminant transport to water resources is important for the development of
From page 125...
... The spatial and temporal scales of a mass balance may vary over several orders of magnitude, depending on the objectives of the study in question. Control volumes may range from entire watersheds as in river basin models to infinitesimal slices as in numerical transport models.
From page 126...
... There is a continuum of massbalance efforts ranging from conceptual mass balance of aggregated data to comprehensive numerical models that operate in small time and space intervals. The requirements for constructing even a simplified, conceptual mass balance may entail substantial data and information collection.
From page 127...
... The committee recommends that at least a conceptual mass balance be developed for nonpoint source pollutants and constituents of concern for TMDLs in all Cycle II study units. The reactivity of a given NPS pollutant may be generic, but the extent of biological and chemical reactions of the pollutant is highly dependent upon site-specific conditions.
From page 129...
... Statistical water quality models range from the very simple concentrationdischarge models described above to the more complex regional multivariate statistical models such as SPARROW (Spatially Referenced Regression on Watershed Attributes)
From page 130...
... To address problems of model selection, application, and analysis, a set of modular modeling tools, termed the Modular Modeling System (MMS; Leavesley, 1997) is being developed by the National Research Program of the USGS.
From page 131...
... PROPOSED IMPLEMENTATION APPROACH FOR THE UNDERSTANDING GOAL OF CYCLE II Several practical aspects of conducting scientific research have to be considered in an evaluation of the potential for successful implementation. In the case of NAWQA, these aspects include preliminary procedures such as defining objectives and selecting targeted studies to meet these objectives.
From page 132...
... In relation to the many objectives, the committee suggests that more thought should be given to how information from multiple study units will be analyzed and integrated to address questions of national significance. The understanding objectives must be more clearly defined and stated in terms of testable hypotheses that can then be addressed by targeted studies designed for that purpose, as in the ASTT example.
From page 133...
... The NIT report recognizes this problem and clearly states that the understanding issues "can only partially be addressed by Cycle II investigations, even in all three groups of study units." With the expressed resource constraints, the number and complexity of the objectives for understanding and the staff resources and expertise issues must be carefully addressed in finalizing plans for targeted studies and modeling implementation. The financial support available will ultimately govern what can be accomplished in Cycle II.
From page 134...
... The proposed approach for Objective U1 is that a large-scale mass-balance analysis will be developed for a selected basin (major stream) and/or major aquifer for selected constituents in most Cycle II study units (Gilliom, 2000b)
From page 135...
... The proximity of a contaminant source to a water resource may be very influential and more important than land use as an explanatory factor. High-resolution data at a subbasin scale and model application may be needed to obtain satisfactory understanding of large-scale natural and anthropogenic contaminant sources.
From page 136...
... To understand the origin of contaminant sources in greater detail, supplementary high-resolution sampling may be needed. Sources of contaminants to streams from runoff and spills are best addressed by storm event sampling, rather than baseflow sampling.
From page 137...
... As noted previously, the example ASTT presents an excellent set of clearly articulated hypotheses for its proposed study (Gilliom et al., 2000~. This example targeted study, designed to investigate sources and transport of agricultural chemicals, is an excellent model for the Cycle II topical teams to follow to develop focus for the objectives and further targeted study development.
From page 138...
... The proposed approach implies that Cycle I data should be analyzed using the space-for-time concept to predict future water quality and its distribution. This objective, however, should be stated separately from the idea of characterizing variability of contaminant sources.
From page 139...
... NAWQA should consider evaluation of the variability of sources and contaminant occurrence as a first step for the objectives related to "understanding contaminant sources"; this should take place prior to subsequent space-for-time and targeted study design. · Sampling design should consider interpolation and indexing considerations that may be necessary to develop as complete a mass balance as possible.
From page 140...
... affect the transport of contaminants along streams. The models and software packages to be used to help implement the above objectives by the planned HST in Cycle II will be coordinated with the needs of other NAWQA national synthesis teams as well as the study units.
From page 141...
... · The current NAWQA program is not geared to the assessment of ephemeral streamflows that can be an important contaminant source in arid areas in particular. NAWQA should develop strategies to sample ephemeral streamflows, especially in perceived high-risk areas, such as those in which contamination could threaten perennial streams, lakes or reservoirs, or shallow groundwater systems.
From page 142...
... Although the NAWQA program has evolved from its original separate surface water and groundwater study units (Hirsch et al., 1988) there still needs to be more emphasis on GW-SW interactions and their effects on water quality in Cycle II.
From page 143...
... The hyporheic zone, or GW-SW ecotone, can be an important component in understanding surface water quality and near-surface groundwater quality in NAWQA study units (Hinkle et al., 2001~. Although there are study units that appear to be surface water dominated (e.g., Willamette Basin, New England Coastal Basins)
From page 144...
... Efforts to couple hyporheic zone modules to existing models should be accelerated, and the committee notes that a hyporheic module has recently been developed for MODFLOW. Since TOPMODEL (Beven, 1997)
From page 145...
... If this means seeking out collaborators and cooperators, then that should be encouraged as well. Recommendation · The hyporheic zone, or groundwater-surface water ecotone, can be an important component in understanding surface water quality and near-surface groundwater quality in NAWQA study units.
From page 146...
... However, focusing its attention only on nutrient enrichment in agricultural streams reduces its ability to contribute to the nationwide debate in all regions. Clearly there are nutrient enrichment problems in urban ecosystems as well, and regulations will not be able to ignore them.
From page 147...
... Thus, even though it will not be directly addressed through targeted studies in the first phase of Cycle II, it will be impossible to consider effects of nutrient enrichment (Ul3) or to consider effects of agricultural (e.g., Objective T6)
From page 148...
... Assessment of Biological Integrity Biological assessments focus on the living components of aquatic ecosystems and use those components to assess ecological health. They are typically used to help diagnose physical, chemical, and biological degradation of water resources and the cumulative effects of multiple sources of pollution.
From page 149...
... In this regard, the USGS's NAWQA program is in excellent position to make a meaningful contribution to the methods debate based on results from Cycle I studies in which it has conducted bioassessments based on fish, benthic invertebrate, and algal assemblages. This should be a top priority of the recently formed Ecological Synthesis Team.
From page 150...
... This data set should be employed to suggest cost-effective ways to use biological monitoring in Cycle II when resource limitations do not permit everything to be measured. In addition to evaluating different indices, it is critical that the Ecological Synthesis Team explore quantitative relationships between biotic indices and other measures of water quality.
From page 151...
... Extrapolation and Forecasting Geographic extrapolation of analyses from NAWQA study units to unmeasured areas and forecasting future water conditions (e.g., based on land management changes) is an essential feature of NAWQA.
From page 152...
... models are expected to play a key role in this extrapolation and forecasting theme. Beyond that, no additional details are presented in the Cycle II implementation guidelines to describe how this will be accomplished, except that consideration will be given to "knowledge of land use and contaminant sources, natural characteristics of the land and hydrologic system, and our understanding of governing processes." Despite the absence of details on extrapolation and forecasting planned for Cycle II, several papers and reports have been prepared by USGS-NAWQA scientists that provide an indication of related techniques that may be applied in Cycle II.
From page 153...
... Modeling of contaminant sources and their transport to water resources, and hence an ability to predict future conditions, are key to the development of efficient management and policies to protect the beneficial uses of the nation's water resources, including drinking water and viable ecosystems. Therefore, the application of water quality models is the cornerstone of water resource management for the future, and this was clearly recognized by the NRC as early as 1990 when model application was recommended for NAWQA.
From page 154...
... The six themes with 17 objectives that describe the understanding goal for Cycle II were developed (in the preliminary planning) by categorization of the wide variety of scientific studies proposed by the Cycle II study units.
From page 155...
... Recommendations for Implementation · The 17 objectives for the understanding goal, as presented in the NIT report, are complex and address too many issues to have a good focus. Further, the process of selecting topics for targeted studies to meet the understanding goal in Cycle II has not yet been clearly defined.
From page 156...
... · The current NAWQA program is not geared to the assessment of ephemeral streamflows that can be an important contaminant source in arid areas in particular. NAWQA should develop strategies to sample ephemeral streamflows, especially in perceived high-risk areas, such as those in which contamination could threaten perennial streams, lakes or reservoirs, or shallow groundwater systems.
From page 157...
... . The USGS' s NAWQA program is in excellent position to make a meaningful contribution to the debate on which biological indices are most meaningful based on results from Cycle I studies in which it has conducted bioassessments based on fish, benthic invertebrate, and algal assemblages.
From page 158...
... Journal of American Water Resources Association 32(4)
From page 159...
... 1997. Nutrient mass balance for the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia.
From page 160...
... Water Resources Research 29(6)
From page 161...
... Geological Survey.


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