Ground Water Vulnerability Assessment Predicting Relative Contamination Potential Under Conditions of Uncertainty (1993) / Chapter Skim
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4 Data and Databases
4 Data and Databases
Pages 104-134
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From page 104... ...
To date most vulnerability assessments have used existing data sources, and have rarely involved new data collection efforts in support of the vulnerability assessment. Since the data available for a particular region are often meager, the attributes of interest are often derived by some type of interpolation of information collected at sparsely distributed locations, sometimes from outside the region of interest, and frequently using data collected at a different spatial scale.
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From page 105... ...
Since public funds are limited, many federal agencies currently are interested more in maintaining and improving the usefulness, accuracy, and availability of existing databases than in embarking on new programs of data collection. This chapter reviews the status of existing information, and describes several databases, their availability, and their use in ground water vulnerability assessments.
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From page 106... ...
The circular established the Federal Geographic Data Committee (FGDC) to promote the coordinated development, use, sharing, and dissemination of surveying, mapping, and related spatial data.
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From page 107... ...
Geological Survey, Department of the Interior Federal Highway Administration, Department of Transportation Office of the Geographer, Department of State Soil Conservation Service, Department of Agriculture U.S. Forest Service, Department of Agriculture U.S.
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From page 108... ...
Several FGDC activities support the development of the NSDI. Town meetings and more direct contacts with groups representing different sectors of the spatial data community provide forums for making the public aware of federal geographic data and discussing roles and opportunities for participating in the NSDI.
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From page 109... ...
The availability and quality of state and local digital databases needed to support ground water vulnerability assessments depend on: (1) the presence of a jurisdictionwide coordination entity, (2)
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From page 110... ...
Some additional digital elevation data are collected as part of operational programs or specialized research projects in other federal, state, and local agencies, and may be available from these sources. Discussion Digital terrain data, which might be used in regional or national ground water vulnerability assessments, are not currently accessible on a nationwide basis with uniform spatial and attribute characteristics.
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From page 111... ...
~ Lit ;^ At e c)
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From page 112... ...
This mapping has been done on aerial photobases at scales of 1:15,840 to 1:31,680 and line maps at a scale of 1:250,000. SCS has established standards for creation of digital soil geographic databases and begun adding to these databases (Reybold and TeSelle 1989~.
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From page 113... ...
. The soil map unit boundaries in each geographic database are linked with soil attribute data to give the extent and properties of the dominant soil series phase in each mapping unit.
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FIGURE 4.2 A conceptual diagram of a soil geographic database (SSURGO) map unit.
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115 FIGURE 4.3 A conceptual diagram of a state soil geographic database (STATSGO) map unit.
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From page 116... ...
FIGURE 4.4 A conceptual diagram of a national soil geographic database (NATSGO) map unit (Adapted from Lytle and Mausbach 1991.
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From page 117... ...
Hence, all map units have inclusions of other soil series with similar and/or dissimilar properties. Soil survey guidelines (USDA 1983)
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From page 118... ...
A subset of SIR that contains most of the soil properties applicable for ground water vulnerability assessments is being compiled in ASCII formatted direct access files as the soil database used in the NLEAP model (Shaffer et al.
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From page 119... ...
In addition, where available, acreage, percent composition of different taxonomic units, and SIR numbers to link SIR data with map unit components are included. When the MUUF database is combined with subsets of estimated soil properties from SIR, the resulting Map Unit Interpretation Record (MUIR)
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From page 120... ...
The NSCDB, which, in part, will replace SIR database, will incorporate site-specific, experimental data, including data means, variances, and associated uncertainties. The development of NSCDB will require the identification of the specific pedon that best describes the dominant soil series phase of each soil map unit.
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From page 121... ...
Vulnerability assessments at the field and watershed scale must consider land use and spatial and temporal variability of the land surface as they affect water movement across and into soil. The development of digital soil geographic databases has not kept pace with demand.
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From page 122... ...
Geologic maps at sufficiently large scales provide the lithologic and structural data from which the information found in SCS soil maps can be placed in a larger context, particularly if lithologic facies are identified (e.g., Anderson 1989~. Geologic and hydrogeologic maps, however, are only progress reports, whose accuracy depends on scale and the expertise of the scientist doing the mapping.
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From page 123... ...
As a result, several natural resource oriented agencies, such as the Forest Service, SCS, National Park Service, Bureau of Land Management, Bureau of Reclamation, and Bureau of Indian Affairs, and similar state government and university entities have developed climate data collection systems and databases to suit their own needs in their areas of jurisdiction. Also, agency coordination in climate data collec
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From page 124... ...
. However, much of this data collection is driven by irrigation water management needs, which do not necessarily match the data needs for ground water vulnerability assessments.
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From page 125... ...
Many climate information providers collect climate data from RCC established networks or from agencies under RCC contract or data archiving services. Three other major efforts are under way to develop better climate databases for the United States.
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From page 126... ...
The system is expected to be a significant new source of computer derived spatial information for use in calibration of spatial data extrapolation models. Over the next decade AWIPS and NEXRAD will be implemented nationwide.
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From page 127... ...
Most land use or land cover mapping projects manually interpret areas from remotely sensed imagery and then digitize class boundaries. The classification scheme applied to LULC data is perhaps the most critical factor in determining the value of this information for ground water vulnerability assessment.
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From page 128... ...
and SCS land use and land cover data collected at the farm and ranch level are valuable because of their level of detail and currency, however, they lack a digital geographic reference. The utility of digital LULC data for ground water vulnerability studies and other applications could be enhanced by the development of a standard LULC classification scheme to achieve consistency in data at the national scale.
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From page 129... ...
MANAGEMENT FACTORS Ideally, management factors such as plant growth, tillage and other soil disturbances with their associated ground cover conditions, irrigation, drainage, conservation practices, grazing, and agrichemical applications should be considered when conducting a ground water vulnerability assessment (USDA 19921. Not all these factors are described in national or regional databases; however, several databases are worthy of note because they address some of these factors, including the National Resources Inventory, the National Agricultural Census of 1987, the Irrigation Water Use Survey of 1988, and several pesticide databases.
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From page 130... ...
and the SCS, collect land information such as land cover and use, irrigation, drainage, crop history, crop yield, erosion rates, and conservation practices such as terracing and residue management for farmers and ranchers who participate in USDA farm programs. This information is collected on a farm field or ranch pasture basis and exists in digital tabular form for much of the country's private croplands.
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From page 131... ...
The MSC concluded that "unless a vision for the National Spatial Data Infrastructure exists and the spatial data bases, policies, and standards are in place to facilitate the access and use of the spatial data on a national scale, opportunities in areas from environment to development will be lost." The MSC report also recommends that federal efforts expand beyond the compilation of various types of spatial databases and development of standards for data exchange to include "more specific measures and standards of content, quality, currency, and performance of various components" of the proposed NSDI. It is not enough to have easy access to existing spatial data; it is important to know how good is the information contained in these databases.
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From page 132... ...
In addition, there exists a wealth of analog maps and photographs that could be converted to the more useful digital format. The collection and synthesis of existing spatial databases has involved the extraordinary efforts of a large number of technical experts.
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1991. Interpreting soil geographic databases.
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From page 134... ...
1985. Spatial variability: Its documentation, accommodation and implication to soil surveys.
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