ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03227.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:The Central Nebraska Basins (NAWQA) study unit includes the Platte River and two major tributaries, the Loup and Elkhorn Rivers. Platte River flows are variable in the western part of the study unit because of diversions, but the Loup and Elkhorn Rivers originate in an area of dune sand covered by grassland that generates consistent base flows. More frequent runoff in the eastern part of the study unit also sustains stream flow. Ground water in the study unit has no regional confining units and the system is a water table aquifer throughout. Macroinvertebrate and fish taxa at biological sampling sites in the state were related to stream flow. One of the four wetland complexes identified in the study unit includes habitat for threatened and endangered bird species. The study unit is an agricultural area that includes row crops, both irrigated and nonirrigated in the eastern and southern parts, and rangeland in the Sand Hills of the western part. A water quality assessment will be based on the differences in environmental setting in each of four subunits within the study unit.]

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03228.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:The environmental setting of the Red River of the North basin within the United States is diverse in ways that could significantly control the areal distribution and flow of water and, therefore, the distribution and concentration of constituents that affect water quality. Continental glaciers shaped a landscape of very flat lake plains near the center of the basin, and gently rolling uplands, lakes, and wetlands along the basin margins. The fertile, black, fine‐grained soils and landscape are conducive to agriculture. Productive cropland covers 66 percent of the land area. The principal crops are wheat, barley, soybeans, sunflowers, corn, and hay. Pasture, forests, open water, and wetlands comprise most of the remaining land area. About one‐third of the 1990 population (511,000) lives in the cities of Fargo and Grand Forks, North Dakota and Moorhead, Minnesota. The climate of the Red River of the North basin is continental and ranges from dry subhumid in the western part of the basin to subhumid in the eastern part.From its origin, the Red River of the North meanders northward for 394 miles to the Canadian border, a path that is nearly double the straight‐line distance. The Red River of the North normally receives over 75 percent of its annual flow from the eastern tributaries as a result of regional patterns of precipitation, evapotranspiration, soils, and topography. Most runoff occurs in spring and early summer as a result of rains falling on melting snow or heavy rains falling on saturated soils. Lakes, prairie potholes, and wetlands are abundant in most physiographic areas outside of the Red River Valley Lake Plain. Dams, drainage ditches, and wetlands alter the residence time of water, thereby affecting the amount of sediment, biota, and dissolved constituents carried by the water.Ground water available to wells, streams, and springs primarily comes from sand and gravel aquifers near land surface or buried within 100 to 300 feet of glacial drift that mantles the entire Red River of the North basin. Water moves through the system of bedrock and glacial‐drift aquifers in a regional flow system generally toward the Red River of the North and in complex local flow systems controlled by local topography. Many of the bedrock and glacial‐drift aquifers are hydraulically connected to streams in the region.The total water use in 1990, about 196 million gallons per day, was mostly for public supply and irrigation. Slightly more than one half of the water used comes from ground‐water sources compared to surface‐water sources. Most municipalities obtain their water from ground‐water sources. However, the largest cities (Fargo, Grand Forks and Moorhead) obtain most of their water from the Red River of the North.The types and relative amounts of various habitats change among the five primary ecological regions within the Red River of the North basin. Headwater tributaries are more diverse and tend to be similar to middle‐reach tributaries in character rather than the lower reaches of these tributaries for the Red River of the North.Concentrations of dissolved chemical constituents in surface waters are normally low during spring runoff and after thunderstorms. The Red River of the North generally has a dissolved‐solids concentration less than 600 milligrams per liter with mean values ranging from 347 milligrams per liter near the headwaters to 406 milligrams per liter at the Canadian border near Emerson, Manitoba. Calcium and magnesium are the principal cations and bicarbonate is the principal anion along most of the reach of the Red River of the North. Dissolved‐solids concentrations generally are lower in the eastern tributaries than in the tributaries draining the western part of the basin. At times of low flow, when water in streams is largely from ground‐water seepage, the water quality more reflects the chemistry of the glacial‐drift aquifer system.Ground water in the surficial aquifers commonly is a calcium bicarbonate type with dissolved‐solids concentration generally between 300 and 700 milligrams per liter. As the ground water moves down gradient, dissolved‐solids concentration increases, and magnesium and sulfate are predominant ions. Water in sedimentary bedrock aquifers is predominantly sodium and chloride and is characterized by dissolved‐solids concentrations in excess of 1,000 milligrams per liter.Sediment erosion by wind and water can be increased by cultivation practices and by livestock that trample streambanks. Nitrate‐nitrogen concentrations also can increase locally in surficial aquifers beneath cropland that is fertilized, particularly where irrigated. Nitrogen and phosphorous in surface runoff from cropland fertilizers and nitrogen from manure can contribute nutrients to lakes, reservoirs, and streams. Some of the more persistent pesticides, such as atrazine, have been detected in the Red River of the North. Few data are available to conclusively define the presence or absence of pesticides and their break‐down products in Red River of the North basin aquifers or streams.Urban runoff and treated effluent from municipalities are discharged into streams. These point discharges contain some quantity of organic compounds from storm runoff, turf‐applied pesticides, and trace metals. The largest releases of treated‐municipal wastes are from the population centers along the Red River of the North and its larger tributaries. Sugar‐beet refining, potato processing, poultry and meat packing, and milk, cheese, and cream processing are among the major food processes from which treated wastes are released to streams, mos

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03229.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:The Rio Grande Valley National Water‐Quality Assessment study unit encompasses about 45,700 square miles in Colorado, New Mexico, and Texas upstream from the gaging station Rio Grande at El Paso, Texas, and includes surface‐water closed basins east of the Continental Divide in New Mexico, and the San Luis Closed Basin in Colorado. The mean annual precipitation ranges from less than 6 to more than 50 inches; potential evapo‐transpiration ranges from less than 35 to more than 80 inches per year. Land use is mainly rangeland, forest land, and cropland. Total irrigated acreage in 1990 was about 914,000 acres and water use was about 3,410,000 acre‐feet. Two structural settings are found in the study unit: alluvial basins and bedrock basins. The alluvial basins can have through‐flowing surface water or be closed basins. The discussion of streamflow and water quality for the surface‐water system is based on four river reaches for the 750 miles of the main stem. The quality of the ground water is affected by both natural process and human activities and by nonpoint and point sources. Nonpoint sources for surface water include agriculture, hydromodification, and mining operations; point sources are mainly discharge from wastewater treatment plants. Nonpoint sources for ground water include agriculture and septic tanks and cesspools; point sources include leaking underground storage tanks, unlined or manure‐lined holding ponds used for disposal of dairy wastes, landfills, and mini

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03230.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:The South Platte River Basin was one of 20 study units selected in 1991 for investigation under the U.S. Geological Survey's National Water‐Quality Assessment (NAWQA) program. One of the initial tasks undertaken by the study unit team was to review the environmental setting of the basin and assemble ancillary data on natural and anthropogenic factors in the basin. The physical, chemical, and biological quality of the water in the South Platte River Basin is explicitly tied to its environmental setting. The resulting water quality is the product of the natural conditions and human factors that make up the environmental setting of the basin.This description of the environmental setting of the South Platte River Basin and its implications to the water quality will help guide the design of the South Platte NAWQA study. Natural conditions such as physiography, climate, geology, and soils affect the ambient water quality while anthropogenic factors such as water use, population, land use and water‐management practices can have a pronounced effect on water quality in the basin. The relative effects of mining, urban, and agricultural land‐ and water‐uses on water‐quality constituents are not well understood. The interrelation of the surface‐water and ground‐water systems and the chemical and biological processes that affect the transport of constituents needs to be addressed. Interactions between biological communities and the water resources also should be considered. The NAWQA program and the South Platte River Basin study will provide information to minimize existing knowledge gaps, so that we may better understand the effect these natural conditions and human factors have on the water‐quality conditions in the basin, now an

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03231.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:In 1991 the Trinity River Basin National Water‐Quality Assessment (NAWQA) was among the first 20 study units to begin investigations under full‐scale program implementation. The study‐unit investigations will include assessments of surface‐water and ground‐water quality. Initial efforts have focused on identifying water‐quality issues in the basin and on the environmental factors underlying those issues. The environmental setting consists of both physical and cultural factors. Physical characteristics described include climate, geology soils, vegetation, physiography, and hydrology. Cultural characteristics discussed include population distribution, land use and land cover, agricultural practices, water use, and reservoir operations. Major water‐quality categories are identified and some of the implications of the environmental factors for water quality

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1993.tb03232.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY