دانلود رایگان ترجمه مقاله آنالیز مکانی استفاده از آب، تنش آب، و تاثیرات انباشت آب ناشی از تولیدات لبنی (نشریه الزویر 2013)

تجزیه و تحلیل مکانی استفاده بالقوه از آب، تنش آب، و تاثیرات انباشت آب ناشی از تولیدات لبنی آمریکا

Geospatial analysis of potential water use, water stress, and eutrophication impacts from US dairy production

Abstract

Water resource impacts from US dairy production include water use (scarcity impacts) and water quality (eutrophication impacts). These impacts are location-specific, depending upon characteristics of the region and watershed where on-farm dairy and feed production occurs. The objectives of this analysis were to evaluate the impact of US on-farm dairy production on water scarcity across the US, and evaluate dairy production’s impact on eutrophication processes within watersheds as well as on the Gulf of Mexico hypoxic zone. The primary water-utilization challenge for dairy producers is irrigation for growing feed rather than on-farm use. Most dairy production in the US does not occur in water stressed areas with the exception of production in some western states. The potential impacts on local (P pollution) and regional (N pollution to the Gulf of Mexico) watershed eutrophication are more likely to occur from feed production than from on-farm dairy activities.

1.1. Water resources management

Water resource demand in a region is generally characterized by the drainage area (Gleick, 1996). Water resources include surface water (streams, rivers, lakes, and reservoirs) and groundwater (riparian and geologic). Most hydrologic characteristics (timing and magnitude of water availability) that define water resources are contained geographically within a drainage area; the exception is geologic groundwater. Geologic groundwater includes water from geologic strata that are not directly connected to a water body. Riparian groundwater resources are those that are directly connected to a stream, river, or lake through a saturated subsurface conveyance.

Management from the watershed level allows the manager and ecological engineer to consider factors beyond chemical pollution in protecting water quality, including habitat destruction, geomorphologic changes, and changes in land use (Ludwig, Matlock, Haggard, Matlock, & Cummings, 2008; Matlock et al., 1994). For programmatic proposes and uniformity, watersheds are often delimited by government agencies. In the United States, the Natural Resources Conservation Service and the United States Geological Survey (USGS) delineate watersheds in a hierarchical scheme with sub-watersheds nested inside watersheds inside larger drainage basins. These delineations are referred to as hydrologic units, and each is identified by a hydrologic unit code (HUC). Data are available from many government databases describing HUC areas (www.nationalatlas.gov). In the US, there are six levels of delineation, with smaller HUCs nested within larger units (Watermolen, 2006). In order of descending area, the HUCs divide the country into 21 hydrologic regions, 222 sub-regions, 352 accounting units, and 2150 cataloging units. Parts of the country are further delineated into watersheds and sub-watersheds.

A hydrologic region is defined by a two-digit HUC and may be the drainage basin of a major river, like the Upper Mississippi, or the combined drainage area of several rivers, such as New England. Hydrologic sub-regions divide regions and include the area drained by a river system, a section of a river and its tributaries in that reach, a closed basin or basins, or a group of streams forming a coastal drainage area (Watermolen, 2006). Sub-regions are defined by a four-digit HUC. The first two digits are the same as the larger regional HUC, and the last two define the sub-region. Accounting units, or basins, subdivide the sub-regions. They are used by the USGS for managing national water data (Watermolen, 2006). Accounting regions are defined by a six-digit HUC. The last two digits of the HUC are the accounting unit; the preceding digits describe the region and sub-region. The most common scale for water resource analysis, and the scale used in this project, is the hydrologic accounting region (HAR, or six-digit HUC).