Geology topics

Lawrence A. Weiss

Publications and source records attributed to Lawrence A. Weiss.

5 recordsLinked to original sources

USGS2001

Salt-front movement in the Hudson River estuary, New York — Simulations by one-dimensional flow and solute-transport models

The Hudson River is being considered for use as a supplemental source of water supply for New York City during droughts. One proposal entails withdrawal of Hudson River water from locations near Newburgh, Chelsea, or Kingston, but the extent to which this could cause the salt front to advance upstream to points where it could adversely affect community water supplies is unknown. The U.S. Geological Survey (USGS) one-dimensional Branch-Network Dynamic Flow model (BRANCH) was used in conjunction with the USGS one-dimensional Branched Lagrangian Solute-Transport Model (BLTM) to simulate the effect of five water-withdrawal scenarios on the salt-front location. The modeled reach contains 132 miles of the lower Hudson River between the Federal Dam at Troy and Hastings-on-Hudson (near New York City). The BRANCH model was calibrated and verified to 19 tidal-cycle discharge measurements made at 11 locations by conventional and acoustic Doppler current-profiler methods. Maximum measured instantaneous tidal flow ranged from 20,000 ft 3 /s (cubic feet per second) at Albany to 368,000 ft 3 /s at Tellers Point; daily-mean flow at Green Island near Troy ranged from 3,030 ft 3 /s to 45,000 ft 3 /s during the flow measurements. Successive ebb- and flood-flow volumes were measured and compared with computed volumes; daily-mean bias was -1.6 percent (range from -21.0 to +23.7 percent; 13.5 percent mean absolute error). Daily-mean deviation between simulated and measured stage at eight locations (from Bowline Point to Albany) over the 19 tidal-cycle measurements averaged +0.06 ft (range from -0.31 to +0.40 ft; 0.21 ft root mean square error, RMSE). These results indicate that the model can accurately simulate flow in the Hudson River under a wide range of flow, tide, and meteorological conditions. The BLTM was used to simulate chloride transport in the 61-mi reach from Turkey Point to Bowline Point under two seasonal conditions in 1990.one representing spring conditions of high inflow and low salinity (April-June), the other representing typical summer conditions of low inflow and high salinity (July-August). Measured chloride concentrations at Bowline Point were used to drive the BLTM simulations, and data collected at West Point were used for calibration. Mean bias in simulated chloride concentration for the April-June 1990 (high flow) data (observed range from 12 to 201 mg/L [milligrams per liter]; 30 mg/L RMSE) was .16 mg/L, and mean bias for the July-August 1990 (low flow) data (observed range from 31 to 2,000 mg/L; 535 mg/ L RMSE) was +126 mg/L. The salt front (saltwater/ freshwater interface) on the Hudson River was defined as the furthest upstream location where the chloride concentration exceeded 100 mg/L. Data from August 1991 were used to evaluate solute transport between West Point and Poughkeepsie because a chloride concentration of 100 mg/L was not observed at Clinton Point in 1990. The BLTM then was used to simulate chloride concentrations at Chelsea Pump Station and Clinton Point. Regression equations, based on daily mean values of specific conductance measured at West Point, were used to estimate daily mean chloride concentrations at Chelsea Pump Station and Clinton Point for model analysis. Mean biases in BLTM-simulated daily mean chloride concentrations for August 1991 were .38 mg/L at Chelsea Pump Station (range from 189 to 551 mg/L; 103 mg/L RMSE) and .9 mg/L at Clinton Point (range from 53 to 264 mg/L; 62 mg/L RMSE). Hypothetical withdrawals at (1) Newburgh, (2) Chelsea, (3) Chelsea and Newburgh, (4) Chelsea and Kingston, and (5) Kingston and Newburgh, were simulated to compute the effects of withdrawals on salt-front movement. Withdrawals of 300 Mgal/d from any combination of Chelsea or Newburgh could result in upstream movement of the salt front of as much as 1.0 mi, given an initial salt-front location between West Point and Rogers Point. Scenarios that included withdrawals at Kingston caused the greatest upstream salt-front movement. Simulation of a 90-day April-June high-flow period during which discharges at Green Island averaged 25,200 ft 3 /s indicated that withdrawals of 1,939 Mgal/d (million gallons per day) at Chelsea Pump Station would not measureably increase chloride concentrations at Chelsea Pump Station under normal tidal and meteorological conditions, but withdrawals at twice that rate (3,878 Mgal/d) could increase the chloride concentration at Chelsea Pump Station to 250 mg/L.

New York↗

USGS1994

Hydraulic modeling of stream channels and structures in Harbor and Crow Hollow Brooks, Meriden, Connecticut

Effects of urbanization have increased the frequency and size of floods along certain reaches of Harbor Brook and Crow Hollow Brook in Meriden, Conn. A floodprofile-modeling study was conducted to model the effects of selected channel and structural modifications on flood elevations and inundated areas. The study covered the reach of Harbor Brook downstream from Interstate 691 and the reach of Crow Hollow Brook downstream from Johnson Avenue. Proposed modifications, which include changes to bank heights, channel geometry, structural geometry, and streambed armoring on Harbor Brook and changes to bank heights on Crow Hollow Brook, significantly lower flood elevations. Results of the modeling indicate a significant reduction of flood elevations for the 10-year, 25-year, 35-year, 50-year, and 100-year flood frequencies using proposed modifications to (1 ) bank heights between Harbor Brook Towers and Interstate 691 on Harbor Brook, and between Centennial Avenue and Johnson Avenue on Crow Hollow Brook; (2) channel geometry between Coe Avenue and Interstate 69 1 on Harbor Brook; (3) bridge and culvert opening geometry between Harbor Brook Towers and Interstate 691 on Harbor Brook; and (4) channel streambed armoring between Harbor Brook Towers and Interstate 691 on Harbor Brook. The proposed modifications were developed without consideration of cost-benefit ratios.

Water-Resources Investigations Report↗

USGS1994

Flow and chloride transport in the tidal Hudson River, NY

A one-dimensional dynamic-flow model and a one-dimensional solute-transport model were used to evaluate the effects of hypothetical public-supply water withdrawals on saltwater intrusion in a 133-mile reach of the tidal Hudson River between Green Island dam, near Troy, N.Y., and Hastings-on-Hudson, N.Y. Regression techniques were used in analyses of current and extreme historical conditions, and numerical models were used to investigate the effect of various water withdrawals. Of four withdrawal scenarios investigated, simulations of a 27-day period during which discharges at Green Island dam averaged 7,090 ft3/s indicate that increasing the present Chelsea pumping-station withdrawal rate of 100 Mgal/d (million gallons per day) to 300 Mgal/d would have the least effect on upstream saltwater movement. A 90-day simulation, during which discharges at Green Island dam averaged 25,200 ft3/s, indicates that withdrawals of 1,940 Mgal/d at Chelsea would not measurably increase chloride concentrations at Chelsea under normal tidal and meteorological conditions, but withdrawals of twice that rate (3,880 Mgal/d) could increase the chloride concentration at Chelsea to 250 mg/L.

Conference Paper↗

USGS1982

Water resources inventory of Connecticut Part 10: Lower Connecticut River basin

The lower Connecticut River basin study area in south-central Connecticut includes 639 square miles and is drained principally by the Connecticut River and by seven smaller streams that flow directly to Long Island Sound between the West River on the west and the Connecticut River on the east. The population in 1979 was estimated to be 210,380. Much of the industrial development and population centers are in the Mattabesset River basin in the northwestern part, and the largest water use is also in the Mattabesset River basin. Precipitation averages 47 inches per year and provides an abundant supply of water. About 20 inches returns to the atmosphere as evapotranspiration, and the remainder either flows directly to streams or percolates to the water table, eventually discharging to Long Island Sound. Small quantities of water are exported from the basin by the New Haven and Meridan Water Departments, and small quantities are imported by the New Britain Water Department and Metropolitan Direct Commission. Precipitation during 1931-60 resulted in an average annual runoff of 302 billion gallons. In inflow from the Connecticut River is added to the average annual runoff, the 4,370 billion gallon s per year is potentially available for water ue. The domestic, institutional, commercial, and industrial (other than cooling water) water use for 1970 was 7 billion gallons, which is only 3 percent of the total water used, whereas 97 percent of the total is cooling water for power plants. Approximately 60 percent of the 7 billion gallons is treated before being discharged back to the streams. The total amount of fresh water used during 1970 was estimated to be 256,000 million gallons (Mgal), of which 247,000 Mgal was used for cooling water at stream electric-generating plants. The quantity for domestic, commercial, industrial, and agricultural used was 9,000 Mgal, which was approximately 120 gallons a day per person. Public water systems providing 70 percent of these requirement and all the systems supplying water met the drinking water standards of the Connecticut General Assembly (1975). Till is widespread and generally provides only small amounts of water. Wells in till normally yield only a few hundred gallons of water daily and may be inadequate during dry periods. The thickness of of till ranges from 0 to 15 feet; a median thickness of 26 feet is estimated from information provided in drillers' logs of 467 wells penetrating underlying bedrock. The till is generally used only as an emergency or secondary source of water. Bedrock aquifers underlie the entire area and include sedimentary and crystalline (igneous and metamorphic) rock types. These aquifers supply small and usually reliable quantities of water to wells and are the chief source of water for many rural homes and farms., About 90 percent of the wells tapping bedrock yield at least 2 gal/min. The median yields from wells tapping aquifers in sedimentary, igneous, and metamorphic rocks are 11, 8, and 6.5 gal/min, respectively. The quantity of water potentially available from stratified drift was estimated on the basis of hydraulic characteristics of the aquifers, mathematical modeling of the aquifer system, and evaluation of natural and induced recharge. Long-term yields estimated or ten areas underlain by significant thickness of stratified drift range from 0.4 to 4.4 million gallons per day (Mgal/d). A change in well spacing or numbering could increase the long-term yields, but detailed modeling verification studies are needed to confirm optimal well locations. The chemical and physical (turbidity, color, taste, and sediment load) quality of water is good. The water if generally low in dissolved solids and is classified as soft to hard. Surface water is less mineralized than ground water, especially during high flow, when it is primarily derived from surface runoff rather than groundwater runoff. A median dissolved-solids concentration of 42 milligrams per liter (mg/L) and median hardness of 18 mg/L were determined from water samples collected from 26 streams during the high-flow period. During the low-flow period, median dissolved-solids concentration of 61 mg/L and median hardness of 27 mg/L were determined from sample from the same streams. The quality of water in stratified-drift and crystalline-rock aquifers is generally better than that in the sedimentary-rock aquifers. Water from 32 wells tapping stratified drift had median dissolved-solids concentrations of 116 mg/L; and 33 wells tapping stratified drift and 42 tapping crystalline rock had median hardness of 73 mg/L and 68 mg/L, respectively. Water from 32 wells tapping sedimentary rock had median dissolved concentrations of 231 and 156 mg/L, respectively. Sedimentary rock generally yields the hardest water. Iron and manganese occur objectionable concentrations in places, particularly in water from streams draining swamps and in water from aquifers either rich in iron and manganese-nearing minerals or where the reducing environment for solution of these minerals is favorable. Concentrations of iron in excess of 0.3 mg/L were found in 35 percent of the high streamflow samples, and in 45 percent of the ground-water samples. Most of the high iron and manganese concentration in streams and aquifers are found east of the Connecticut River. Human activities and tidal influence along the coast have modified the quality of water in much f the study area. The greatest influence from human activities has been in the northwestern part, in the Mattabesset River basin. There, the quality of water has been affected by domestic and animal wastes, which cause high dissolved-solids concentrations, high nitrate and phosphate loads and high bacterial counts. In the entire area, high nitrate in groundwater occur only locally, and its presence in an individual water supply is chiefly a function of its proximity to sources of contamination, of well construction, and of thickness of overburden. Thirty public-supply wells did have water that had high sodium concentrations or objectionable iron and manganese concentrations, but these are not considered health hazards in the concentrations found in the water samples. Streams, wetlands, and some aquifers along the sough boundary of the basin contain salty water because of tidal movement or extensive ground-water withdrawals. High sediment concentrations also occur as a result of tidal influence in this area.

Connecticut↗

USGS1981

Water resources inventory of Connecticut Part 7: upper Connecticut River basin

The 508 square miles of the upper Connecticut River basin in north-central Connecticut include the basins of four major tributaries: the Scantic, Park, and Hockanum Rivers, and the Farmington River downstream from Tariffville. Precipitation over this area averaged 44 inches per year during 1931-60. In this period, an additional 3,800 billion gallons of water per year entered the basin in the main stem of the Connecticut River at the Massachusetts state line, about 230 billion gallons per year in the Farmington River at Tariffville, and about 10 billion gallons per year in the Seantic River at the Massachusetts state line. Some water was also imported from outside the basin by water-supply systems. About half the precipitation, 22.2 inches, was lost from the basin by evapotranspiration; the remainder flowed out of the study area in the Connecticut River at Portland. Variations in streamflow at 41 long-term continuous-record gaging stations are summarized in standardized graphs and tables that can be used to estimate streamflow characteristics at other sites. For example, mean-flow and two low-flow characteristics: (1) the 7-day annual minimum flow for 2-year and (2) 10-year recurrence intervals, have been determined for many partial-record stations throughout the basin. Of the 30 principal lakes, ponds, and reservoirs, two have usable storage capacities of more than 1 billion gallons. The maximum safe draft rate (regulated flow) of the largest of these, Shenipsit Lake at Rockville, is 6.5 million gallons per day for the 2-year and 30-year recurrence intervals (median and lowest annual flow). Floods have occurred within each month of the year but in different years. The greatest known flood on the Connecticut River was in March 1936; it had a peak flow of 130,000 cubic feet per second at Hartford. Since then, major floods have been reduced by flood-control measures. The major aquifers underlying the basin are composed of unconsolidated materials (stratified drift and till) and bedrock. Stratified drift overlies till and bedrock in valleys and lowlands in the eastern and western parts and in most of the broad central valley. The stratified drift generally ranges in thickness from 10 feet in small valleys to more than 200 feet in the Connecticut River Valley. Bedrock underlies the entire basin and is composed of (1) interbedded sedimentary and igneous rocks and (2) crystalline rocks. Ground-water sources yield from several million gallons per day from large well fields to 1 gallon per minute from single wells. Yields of 100 gal/min or more are most commonly obtained from screened wells tapping stratified-drift aquifers; amounts can be calculated by use of a series of graphs in conjunction with estimates of aquifer transmissivity and thickness. Eighteen areas underlain by good aquifers are selected as the most favorable locations for large-scale development of ground water. Selection of these areas is based on estimates of aquifer characteristics and the amount of water potentially available from induced infiltration of streamflow at low-flow conditions. Small to moderate water supplies can generally be obtained from any of the aquifers. Wells in bedrock yield at least a few gallons per minute at most sites. The probability of obtaining an adequate yield for domestic supply is greater in sedimentary than in crystalline bedrock and is also greater in stratified-drift overburden than in till. Where unaffected by man's activities, the water is of the calcium magnesium bicarbonate type, is generally low to moderate in dissolved-solids concentration, and ranges from soft to hard. In general, streamflow is less mineralized than ground water, particularly when it consists largely of direct runoff. However, streams become more highly mineralized during low-flow conditions, when most flow consists of more highly mineralized water discharged from aquifers. The median dissolved-solids concentration in water from 25 stream sites was 113 mg/L (milligrams per liter) during high flow, and 148 mg/L during low flow within the study period. Iron and manganese occur naturally in objectionable concentrations in some streams draining swamps and in some waters draining from sedimentary bedrock which contains iron- and manganese-bearing minerals. Man's activities have affected the water quality of streams in much of the area, particularly in the Hockanum and Park River basins. The degradation in quality in these streams is shown by wide and erratic changes in dissolved-solids concentration, excessive amounts of trace elements, a low dissolved-oxygen content, and abnormally high temperatures. Ground water within this area is degraded principally by induced infiltration of surface water that contains chemical wastes, by leachate from wastes stored or disposed of on the ground, and by effluents discharged from septic tanks. The quantity and quality of water are satisfactory for a wide variety of uses, and, with suitable treatment, the water may be used for most purposes. The total amount of water used in 1968 was more than 100 billion gallons. About 80 percent of this was used for industrial purposes, and 90 percent of the industrial water was obtained from surface-water sources. About 85 percent of the population was supplied with water for domestic use by 15 major public and municipal systems and 25 private associations. Analyses of water from the 13 largest systems show generally good quality.

Connecticut↗