Holzer, Thomas L.

English

Colorado Law

University of Colorado Law School Colorado Law Scholarly Commons Water Resources Allocation: Laws and Emerging Issues: A Short Course (Summer Conference, June 8-11) 1981 6-8-1981 Land Subsidence and Ground-Water Pumping: Outline Thomas L. Holzer Follow this and additional works at: https://scholar.law.colorado.edu/water-resources-allocation-laws-and-emerging-issues  Part of the Agriculture Law Commons, Animal Law Commons, Contracts Commons, Dispute Resolution and Arbitration Commons, Energy and Utilities Law Commons, Environmental Law Commons, Indian and Aboriginal Law Commons, Legislation Commons, Litigation Commons, Natural Resources and Conservation Commons, Natural Resources Law Commons, Natural Resources Management and Policy Commons, Oil, Gas, and Mineral Law Commons, Property Law and Real Estate Commons, Recreation, Parks and Tourism Administration Commons, State and Local Government Law Commons, Urban Studies Commons, Water Law Commons, and the Water Resource Management Commons Citation Information Holzer, Thomas L., "Land Subsidence and Ground-Water Pumping: Outline" (1981). Water Resources Allocation: Laws and Emerging Issues: A Short Course (Summer Conference, June 8-11). 10. https://scholar.law.colorado.edu/water-resources-allocation-laws-and-emerging-issues/10 Reproduced with permission of the Getches-Wilkinson Center for Natural Resources, Energy, and the Environment (formerly the Natural Resources Law Center) at the University of Colorado Law School.     Thomas L. Holzer, Land Subsidence and Ground-Water Pumping: Outline, in WATER RESOURCES ALLOCATION: LAWS AND EMERGING ISSUES (Natural Res. Law Ctr., Univ. of Colo. Sch. of Law 1981).  Reproduced with permission of the Getches-Wilkinson Center for Natural Resources, Energy, and the Environment (formerly the Natural Resources Law Center) at the University of Colorado Law School.  OUTLINELAND SUBSIDENCE AND GROUND-WATER PUMPINGBYTHOMAS L. HOLZERGEOLOGISTU. S. GEOLOGICAL SURVEY345 MIDDLEFIELD ROADMENLO PARK, CALIFORNIA 94025WATER RESOURCES ALLOCATION:LAWS AND EMERGING ISSUESTHE UNIVERSITY OF COLORADO SCHOOL OF LAWI. INTRODUCTIONA. Summary Land subsidence is loss of elevation of the landsurface. Although it can be caused by a variety of man-induced processes, the most areally extensive landsubsidence in the United States has been caused by ground-water pumping from unconsolidated aquifer systems. Suchpumping has caused a cumulative area of more than 22,000km2 (8500 mi 2 ), an area approximately the size of theState of New Jersey, to subside more than 30 cm (1 ft).The maximum subsidence exceeds 8.8 m (29 ft) which wasobserved in the San Joaquin Valley, California, from 1926to 1972. Although effects from subsidence are mostdramatic in coastal areas subject to flooding upon loss ofelevation, regional differential subsidence has had acostly impact on the design and operation of canals andaqueducts in the western United States. In addition,rupture or failure of the ground has locally accompaniedland subsidence, damaging many engineered structures andposing limitations to land use in subsiding areas.B. Research Sources 1. Poland, J. F., and Davis, G. H., 1969, Land subsidencedue to withdrawal of fluids in Varnes, D. V., andKiersch, G., eds. Reviews in Engineering Geology, v.2, Geological Society of America, pp. 187-269--Thisarticle describes the occurrence of subsidence on aworld-wide basis and reviews the mechanisms ofIisubsidence.2. Helm, D. C., 1976, One-dimensional simulation ofaquifer system compaction near Pixley, California,2. Stress-dependent parameters: Water ResourcesResearch, v. 12, no. 3, pp. 375-391--This technicalarticle describes and illustrates the precision of thebest of the digital models available for predictingland subsidence.3. Holzer, T. L., 1977, Ground failure in areas ofsubsidence due to ground-water decline in the UnitedStates in International Land Subsidence Symposium,2nd, Anaheim, 1976, Proceedings: InternationalAssociation of Scientific Hydrology, Publication No.121, pp. 423-k33--This article summarizes anddescribes the occurrence of ground failure associatedwith land subsidence in the United States.4. Holzer, T. L., 1979, Elastic expansion of thelithosphere caused by ground-water depletion: Journalof Geophysical Research, v. 84, no. 89, pp. 4689-4698--This article examines the potential for deep-seatedcrustal movements caused by ground-water mining.5. Brah, W. J., and Jones, L. L., 1978, Institutionalarrangements for effective groundwater management tohalt land subsidence: Texas Water Resources InstituteTechnical Report No. 95, Texas A & M, 194 p.--Thisreport evaluates the alternative arrangements oflegal, economic, and political institutions that were12considered in order to arrest subsidence in theHouston-Galveston, Texas, area where subsidence of thecoastal area was costing approximately $31.7 millionper year by the 1970's.6. Lucas, C. V., and James, L. B., 1977, Land subsidenceand the California State Water Project in Internation-al Land Subsidence Symposium, 2nd, Anaheim, 1976,Proceedings: International Association of ScientificHydrology, Publication No. 121, pp. 533-543--Thisnontechnical article describes the effect of landsubsidence on the design of the California Aqueduct.7. Poland, J. F., Lofgren, B. E., and Riley, F. S., 1972,Glossary of selected terms useful in studies of themechanics of aquifer systems and land subsidence dueto fluid withdrawal: U. S. Geological Survey Water-Supply Paper 2025, 9 p.--A well-written glossary ofsubsidence terms.Water Table-Confining BedNAFAIMAIIIMINNAWConfin•dAquiferCZW:1>anfarAtircztZZ22>Land SurfaceWater-table--AquiferII. CAUSE OF LAND SUBSIDENCEA. Idealized Aquifer System BedrockA A	 A Is	A A 1,AS A	 P	 AAA*	 P	 P ARFAT	 PA	 $	 A I A I A	 Pv	 AP P A	 A	 Y. AA • A	 AA	 5Subeidence-prone areas typically are underlain byunconsolidated (nonlithified) sediments that consist ofalternating layers of sand, silt, and clay. When ground-water is pumped from these sediments, the water istransmitted laterally to pumping wells in the sandlayers. The fine-grained clay and silt layers behave asbarriers to rapid movement of ground-water. Givensufficient time, sometimes measured in years or decades,these fine-grained layers may transmit significantquantities of water to the sand beds and ultimately to thepumping wells. The sand beds and clay and silt beds arecalled aquifers and aquitards, respectively. Laterallyextensive aquitards that are particularly slow intransmitting water are called confining beds and14compartmentalize the aquifer such that pumping from oneaquifer may have negligible effect on adjacent aquifers.B. Subsidence Mechanism When water levels are lowered by ground-water pumping, thewater pressure decreases in the pores of the sedimentsfrom which the ground-water is withdrawn. Because thewater pressure in the pores helps support the weight ofoverlying sediments, the decrease of pore pressure causesmore of the weight of the overlying sediments to betransferred to the intergranular skeleton of thesediments. At the depths encountered in aquifer systems,clay and silt beds, i.e., aquitards, often are verycompressible and compact (decrease of pore volume)irreversibly as the weight of the overlying sediments isslowly transferred to the intergranular skeletons.Because the lateral extent of these beds typically is muchgreater than their depth, 100 percent of the compaction istransmitted to the land surface and is manifested as landsubsidence.III. SUBSIDING AREAS AND METHODS OF DETECTIONA. Subsiding Areas in the United States More than 15 areas in the United States have experiencedsubsidence caused by ground-water withdrawal. Most ofthese areas occur in the Gulf Coast and in valleys in thewestern United States. The areas vary greatly in sizeranging approximately from 100 to 10,000 km2 (40 to 4,000mi2 ). The three largest areas of land subsidence are the15Houston-Galveston, Texas, area, the San Joaquin Valley,California, and south-central Arizona. Land subsidenceaffects both rural and urban areas.B. Characteristics of Subsiding Areas Subsidence-prone areas in general are topographically flatand are underlain by thick geologically youthful sediments(less than 5 million years old) deposited by a variety ofgeologic agents including streams, lakes, and oceans. Thedeposits most prone to subsidence are those that havesignificant amounts of clays and silts and have hadrelatively simple geologic histories. Deposits squeezedby tectonic forces or previously weighed down by sedimentsnow eroded away, tend to be less compressible and not assubsidence prone.C. Subsidence Detection Subsidence usually is first detected before it is ofpractical consequence on the basis of resurveys ofpreexisting bench mark networks in an area. Surveytechniques are required that are more precise than thoseused for common land surveys. Such precise surveys areroutinely performed by many different governmentagencies. Subsidence also can be detected by speciallyinstrumented wells designed to measure the compactionwithin the aquifer system.IV. EFFECTSA. Loss of Surface Elevation Lowering of the land surface is of greatest concern near16bodies of surface water, particularly oceans and lakes,because of the potential for of inundation and theincreased hazard from tidal flooding. Costs associatedwith such flooding in the Houston-Galveston, Texas, areaare estimated to exceed $30 million per year.B. Tilting of the Land Surface Differential subsidence can wreak havoc on the operationof water-conveyance structures dependent on gravityflow. Special studies and design are required for suchstructures in subsiding areas.C. Well Damage Compaction within the aquifer system can cause wells tofail by shortening their casing to the point ofcollapse. Such collapse typically destroys theproductivity of the well, thereby necessitating itsreplacement.D. Ground failure Renewed aseismic movement of geologic faults anddevelopment of long tension cracks commonly accompany landsubsidence. Fault scarps as long as 16 km (10 mi) and ashigh as 1 m (3 ft) have been observed. Damage toengineered structures, particularly residences and otherbuildings, commonly is devastating from these faults. Inundeveloped areas, faults and tension cracks imposerestrictions on future land use.E. Decreased Storage Capacity of Aquifer System Water obtained from clay and silt beds during their17compaction is "mined" water because the compaction processis irreversible. In other words, the storage capacity ofan aquifer system is permanently diminished by thecompaction, so that less water will be available duringany subsequent cycles of recharge and depletion.F. Crustal Movements The mass of the water removed from the clay and silt bedsduring their compaction represents a permanent unloadingof the earth's crust. When mass losses are large, theearth's crust beneath the aquifer system may begin to moveslowly upward in response to the decreased weight on it.In seismically active areas, earthquakes might betriggered by such movements.V. ASSIGNING RESPONSIBILITIESA. Technical Evaluation In order to identify parties responsible for damagesassociated with land subsidence one must know what part ofthe aquifer system is compacting and which parties areresponsible for the water-level declines in that part ofthe system. In general, detailed subsurface informationwill be required as will Modelling of the ground-watersystem. It is technically feasible to identify bothelements.B. Scientific Expertise In well-studied areas, government agencies may havealready performed much of the analyses required for atechnical evaluation. In less well-studied areas,geotechnical (soils engineering) or water-resourceexpertise is required for appropriate analyses.VI. PREDICTION OF SUBSIDENCEA. Active Subsidence Areas The reliability of subsidence prediction in areas where itis ongoing depends on the amount of information available,particularly subsurface geology and water-level andleveling or survey data. Given adequate information andthe future water-level declines, accurate predictions canbe made.B. Undeveloped Areas Prediction of subsidence in areas of proposed ground-waterdevelopment can be made by either (1) comparing them withnearby developed areas with similar subsurface geology or(2) geotechnical testing of representative core samplesobtained by drilling. Predictions by either of thesetechniques generally are imprecise and permit onlyqualitative assessments of the subsidence potential.19

Land Subsidence and Ground-Water Pumping: Outline

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Land Subsidence and Ground-Water Pumping: Outline

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