Water-Level Trends and Pumpage in the Cambrian and Ordovician Aquifers in the Chicago Region: 1980 - 1985
Notice bibliographique
Résumé
This report considers pumpage and water-level changes from 1980 through 1985 in deep sandstone wells penetrating the Cambrian and Ordovician aquifer system in northeastern Illinois, the most highly developed aquifer system for large ground-water supplies in Illinois.The term "Cambrian and Ordovician aquifer system" is an unofficial designation for the "Cambrian-Ordovician Aquifer" in northeastern Illinois that has been described in previous reports.Its usage in this report is for convenience only, since formal names of hydrostratigraphic units in Illinois are in the process of change to reduce confusion with rock stratigraphic terminology (Visocky et al., 1985).The Cambrian and Ordovician aquifer system is encountered at depths ranging from less than 300 feet in areas of central northern Illinois to an average of about 500 feet below land surface at Chicago.The aquifer system has an average thickness of 1000 feet and is composed chiefly of sandstones and dolomites: most of the water is obtained from the sandstones.In this report, emphasis has been given to eight counties of the Chicago metropolitan area.Pumpage from deep wells for public and self-supplied industrial supplies in the Chicago region increased from 200,000 gallons per day (gpd) in 1864 to 175.9 million gallons per day (mgd) in 1980 and by 1985 declined to 157.7 mgd.Peak pumpage of 182.9 mgd occurred in 1979.As a result of the pumpage, artesian pressure in the Cambrian and Ordovician aquifer system declined more than 850 feet in Chicago.Pumpage from deep wells in the Chicago region is concentrated in northwestern and western Cook County, eastern Du Page and eastern Kane Counties, and around Joliet in northwestern Will County.Heavy pumpage from deep wells outside the Chicago region occurs at Rockford in southeastern Winnebago County, Belvidere in south central Boone County, De Kalb-Sycamore in central De Kalb County, Rochelle in southeastern Ogle County, and Ottawa-Peru in central and west central La Salle County.Numerous other municipalities and self-supplied industries throughout northeastern Illinois pump small to large quantities of water from deep wells.During the period from October 1980 through December 1985, pumpage from deep wells in the Chicago region decreased from 175.9 mgd to 157.7 mgd, a decrease of 18.2 mgd or 10.3 percent.This is the first time that there has been an extended period of decreased pumpage from deep wells in the area since the post-depression pre-World War II period.Changes in pumpage primarily reflect the transition from use of deep wells to water from Lake Michigan for public and industrial supplies, decreasing use of deep wells by self-supplied industries, and use of Fox River water to supplement the public water supply at Elgin in northeastern Kane County.As a result of this transition, water levels in deep wells in some areas of the Chicago region have risen during the period.However, throughout most of the area, and for the region as a whole, the average trend continues downward, because total deep well pumpage continues to exceed the sustained yield.Average annual water-level changes during the 5-year period varied from a rise of approximately 2 feet in Will County to a decline of 9 feet in Du Page County and averaged a decline of about 3 feet.This is the lowest average decline since detailed records began in the 1950s.Withdrawals for the 1980-1985 period within the Chicago region continued to exceed the practical sustained yield of the Cambrian and Ordovician aquifer system, as they have each year since before 1950, with the result that ground-water users continue to mine water and to borrow water from future generations.By the end of 1985, the upper and some of the middle units of the aquifer system had already been dewatered in many areas, with some pumping levels exceeding 1000 feet.In spite of the recent decrease in deep well pumpage, withdrawals continue to exceed the practical sustained yield by a ratio of more than 2 to 1. Continued heavy withdrawals and declining water levels are major factors in the acute concern regarding the capability of the aquifers to continue to provide a significant share of the water supply for northeastern Illinois.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».