The depth to the water table can be determined by installing wells that penetrate the top of the saturated zone just far enough to respond to water table fluctuations. Preparation of a water-table map requires that only wells that have their well screens installed near the water table be used. If the depth to water is measured at a number of such wells throughout an area of study, and if those water levels are referenced to a common datum such as sea level, the data can be contoured to indicate the configuration and altitude of the water table (Winter and others, 1998).
In addition to various practical uses of a water-table map, such as estimating an approximate depth for a proposed well, the configuration of the water table provides an indication of the approximate direction of ground-water flow at any location on the water table. Lines drawn perpendicular to water-table contours usually indicate the direction of groundwater flow along the upper surface of the groundwater system (figures 21A-C). The water table is continually adjusting to changing recharge and discharge patterns. Therefore, to construct a water-table map, water-level measurements should ideally be made at approximately the same time, and the resulting map is representative only of that specific time. These are called "synoptic" water level measurements.
Water levels in the upper glacial aquifer (water table), Magothy aquifer, and Lloyd aquifer on Long Island have previously been mapped in detail and are depicted in many reports. The first water-table map was compiled in 1903 by Burr and others (1904) for the New York State Water Power Control Commission and the New York State Conservation Department (Burr and others, 1904).
Other water-table maps for Long Island were compiled by Veatch and others (1906) for 1903; Spear (1912) for 1908; Suter (1937) for 1936; Jacob (1945) for 1943; Lusczynski and Johnson (1951) for 1951; Kimmel (1971) for 1970; Koszalka and Koch (1971) for 1971; Koszalka (1975) for 1974; Vaupel and others (1977) for 1943, 1959, 1966, and 1972; Nakao and Erlichman (1978) for 1975; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others (1998) for 1997; Busciolano (2002) for 2000, and Monti and others (2009) for 2006.
The first potentiometric-surface map of the Magothy aquifer was compiled by Koch and Koszalka (1973) for 1972. Other Magothy aquifer maps were compiled by Prince (1976) for 1975; Vaupel and others (1977) for 1959, 1966, and 1972; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others(1998) for 1997; Busciolano (2002) for 2000, and Monti and others (2009) for 2006.
The first potentiometric-surface map of the Lloyd aquifer was compiled by Lusczynski (1952) for 1947. Other Lloyd aquifer maps were compiled by Rich and others (1975) for 1975; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others (1998) for 1997; and Monti and others (2009) for 2006.
The most recent (2010) representation of the potentiometric surfaces of the water table, Magothy and Lloyd aquifers included depth to water information (Monti and others, 2013). These two links are derived products of Monti and others (2013) as an interactive map interface:
Source: Potentiometric Surface 2010
Source: Depth to Water 2010
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Table of Contents
Below are other science projects associated with this project.
Long Island Water Availability
Long Island Precipitation
NWIS - the USGS Data Archive
Long Island Surface Water - Streamflow
Long Island Groundwater Levels
Long Island Water Use
Long Island Groundwater Budget
Long Island Inflow to the Groundwater System
Long Island Outflow from the Groundwater System
Long Island Water Suitability
Long Island Water Suitability Case Studies
Long Island Groundwater System Potential Hazards
- Overview
The depth to the water table can be determined by installing wells that penetrate the top of the saturated zone just far enough to respond to water table fluctuations. Preparation of a water-table map requires that only wells that have their well screens installed near the water table be used. If the depth to water is measured at a number of such wells throughout an area of study, and if those water levels are referenced to a common datum such as sea level, the data can be contoured to indicate the configuration and altitude of the water table (Winter and others, 1998).
In addition to various practical uses of a water-table map, such as estimating an approximate depth for a proposed well, the configuration of the water table provides an indication of the approximate direction of ground-water flow at any location on the water table. Lines drawn perpendicular to water-table contours usually indicate the direction of groundwater flow along the upper surface of the groundwater system (figures 21A-C). The water table is continually adjusting to changing recharge and discharge patterns. Therefore, to construct a water-table map, water-level measurements should ideally be made at approximately the same time, and the resulting map is representative only of that specific time. These are called "synoptic" water level measurements.
Sources/Usage: Public Domain.Figure 21. Using known altitudes of the water table at individual wells (A), contour maps of the water-table surface can be drawn (B), and directions of ground-water flow along the water table can be determined (C) because flow usually is approximately perpendicular to the contours. Groundwater moves along flow paths of varying lengths in transmitting water from areas of recharge to areas of discharge (Winter and others, 1998).(Public domain.) Water levels in the upper glacial aquifer (water table), Magothy aquifer, and Lloyd aquifer on Long Island have previously been mapped in detail and are depicted in many reports. The first water-table map was compiled in 1903 by Burr and others (1904) for the New York State Water Power Control Commission and the New York State Conservation Department (Burr and others, 1904).
Other water-table maps for Long Island were compiled by Veatch and others (1906) for 1903; Spear (1912) for 1908; Suter (1937) for 1936; Jacob (1945) for 1943; Lusczynski and Johnson (1951) for 1951; Kimmel (1971) for 1970; Koszalka and Koch (1971) for 1971; Koszalka (1975) for 1974; Vaupel and others (1977) for 1943, 1959, 1966, and 1972; Nakao and Erlichman (1978) for 1975; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others (1998) for 1997; Busciolano (2002) for 2000, and Monti and others (2009) for 2006.
The first potentiometric-surface map of the Magothy aquifer was compiled by Koch and Koszalka (1973) for 1972. Other Magothy aquifer maps were compiled by Prince (1976) for 1975; Vaupel and others (1977) for 1959, 1966, and 1972; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others(1998) for 1997; Busciolano (2002) for 2000, and Monti and others (2009) for 2006.
The first potentiometric-surface map of the Lloyd aquifer was compiled by Lusczynski (1952) for 1947. Other Lloyd aquifer maps were compiled by Rich and others (1975) for 1975; Donaldson and Koszalka (1983) for 1979; Doriski (1986) for 1983; Doriski (1987) for 1984; Busciolano and others (1998) for 1997; and Monti and others (2009) for 2006.
The most recent (2010) representation of the potentiometric surfaces of the water table, Magothy and Lloyd aquifers included depth to water information (Monti and others, 2013). These two links are derived products of Monti and others (2013) as an interactive map interface:
Source: Potentiometric Surface 2010
Source: Depth to Water 2010
_______________________________
Table of Contents
- Science
Below are other science projects associated with this project.
Long Island Water Availability
The foundation of any groundwater analysis, including those analyses whose objective is to propose and evaluate alternative management strategies, is the availability of high-quality data. Some, such as precipitation data, are generally available and relatively easy to obtain at the time of a hydrologic analysis. Other data and information, such as geologic and hydrogeologic maps, can require...Long Island Precipitation
The National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC) offers several types of climate information generated from examination of the data in the archives. These types of information include record temperatures, record precipitation and snowfall, climate extreme statistics, and other derived climate products. A collection of statistical weather and climate...NWIS - the USGS Data Archive
As part of the U.S. Geological Survey's (USGS) program for disseminating water data within USGS, to USGS cooperators, and to the general public, the USGS maintains a distributed network of computers and fileservers for the acquisition, processing, review, and long-term storage of water data. This water data is collected at over 1.5 million sites around the country and at some border and...Long Island Surface Water - Streamflow
Surface water current conditions are based on the most recent data from on-site automated recording equipment. Measurements are commonly recorded at a fixed interval of 15 to 60 minutes and transmitted by satallite uplink or telephone telemetry to the USGS every hour. Values may include "Approved" (quality-assured data that may be published) and/or more recent "Provisional" data (of unverified...Long Island Groundwater Levels
Water-level measurements from observation wells are the principal source of information about the hydrologic stresses acting on aquifers and how these stresses affect groundwater recharge, storage, and discharge (Taylor and Alley, 2001). Water-level measurements are made by many Federal, State, and local agencies.Long Island Water Use
The U.S. Geological Survey's National Water-Use Information Program (NWUIP) is responsible for compiling and disseminating the nation's water-use data. The USGS works in cooperation with local, State, and Federal environmental agencies to collect water-use information. USGS compiles these data to produce water-use information aggregated at the county, state, and national levels. Every five years...Long Island Groundwater Budget
A groundwater system consists of a mass of water flowing through the pores or cracks below the Earth's surface. This mass of water is in constant motion. Water is constantly added to the system by recharge from precipitation, and water is constantly leaving the system as discharge to surface water and as evapotranspiration. Each groundwater system is unique in that the source and amount of water...Long Island Inflow to the Groundwater System
Precipitation that infiltrates and percolates to the water table is Long Island's only natural source of freshwater because the groundwater system is bounded on the bottom by relatively impermeable bedrock and on the sides by saline ground water or saline bays and the ocean. About one-half the precipitation becomes recharge to the groundwater system; the rest flows as surface runoff to streams or...Long Island Outflow from the Groundwater System
The flow of water leaving, or discharging, the groundwater system of Long Island occurs naturally through streams, as base flow, at the coastline as shoreline discharge and sub-sea discharge, and through pumping wells as withdrawals. Estimates of each component of outflow from the groundwater system is presented and summarized in this section using streamflow measurements, and a compilation of...Long Island Water Suitability
Groundwater quality may be affected by natural and human factors (Johnston, 1988). Although the vulnerability of groundwater to contamination from the land surface is influenced by many factors, the degree of aquifer confinement, the depth of the well, and the surrounding land use are primary key factors that influence shallow groundwater quality.Long Island Water Suitability Case Studies
A collection of studies that focused on the quality of groundwater and surface water, are presented in this section. The reports associated with these areas of water quality concerns are linked as an online source for further reading.Long Island Groundwater System Potential Hazards
Hazards which may impact the ground water system adversely are presented in this web page. The impacts of these hazards are only shown here as a topic for further discussion and may need to be investigated with further details.