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Introduction to the 28th international geological congress symposium on the hydrogeology of Wetlands
.hmma/~!1 lt?'.!r¢~k~g?'.141 ( 19931 1-3 IEIscvicrScien,~c Publishers B.V.. Amsterdam
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Introduction to the 28th International Geological Congress Symposium on the Hydrogeology of Wetlands Wetlands are hydrologic features that occur in physiographic and climatic settings that favor the accut~ulation, or retention, of surface water and (or) soil water, Depending oll their physiographic position in the landscape and the climate of tile setting, wedands interact in varying amounts with all componenls of the hydrologic sy~teln; atmospheric water, surface water, and ground water. The terrestrial wa~cr components, ground water and surface water, are controlled largely by geologic characteristics such as land-surface slope, permeability of soils, and hy~raulic characteristics of the underlying geologic framework. Depending on the~e terrestrial features as well as climate, some landscapes contain extensive wettxnds and others contain only a few widely scattered wetlands. It is increasingly being recognized that understanding the hydrologic !;=nctions of wetlands is fundamental to wlderstanding the chemical and biological characteristics of wetlands. I'urthevnore, it is also recognized that the effectiveness of many wetland-management practices is limited because of inadequate understanding of the basic hydrologic processes associated with the wide variety of wetland types. For ~xample, it is commonly thought that surface water is the primary source of t~..rrestrial wa~er input to wetlands; yet, many wetlands are primarily ground-water discharge features, and the persistence el" the wetness is the result of a re!~tively stable influx of ground water throughom changing seasonal and a~ auai climatic cycles. Construction of wetlands to replace destroyed wetland::; can be successful only if the ceplacement wetland has the same hlvdrogeologic and climatic setting as the destroyed wetland. For example, th~ replacement of a wetland that is dependent on ground waIer fc,r its water and chemical inlc~ut needu to be located in a similar ground-wa'.er discharge area. It would be eb'-urd to construct a ground-water rechar:;e-type wetland in a ground-wa~:er discharge area, or conversely, to construct a ground*water discharge-type wetiand in a ground-water recharge area, and expect the constructed wetland -.':obe an exact replacement for the natural wetland. Many water-development, !and-sLrfaec development, and landscapemanagement practices can nit;eel lhe hydrology of wetlands in varying ways and deglecs. These practices include weather modification, storage of surface f~}22~16941931506.00 ~,ci19'-)3~,-- ElsevierSciencePublishers B.V. All righls reserved
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| t : W|N1ER AND Nt R i,I AMAS
water, drainage of sure)ice water and soil water, urbar~ization such as paving and sewering, road building, changes in land use, and alteration of plant communities. In addition, a number of studies have suggt~sted thal tile development of ground-water resources could have a prc,lkmnd effect on groundwater flow syslems associated with wetlands, and theretbre, on the wetlands thenlselves. Such concerns are commonly voiced in developed semiarid countries, where intensive ground-water extraction is relatively recent. In ott,,er countries that have similar development, bm where ground-water use began well before the ecological movement, wellands may have completely disappeared without public concern: therelk~re, the literature contains few well-documented cases of the effect of ground-water development on wetlands. However, the paper by Suso and Llamas (this issue) discusses the strong relation between the hydrogeologic system and the ecosystems of Donana National Park, Spain, which is considered to be the most ecologically important remaining wetland in soulhern Ezlrope. According to the paper, ground-water pumpage for a nearby irrigation project may cause the destruction of wetlands in Don~ina National Park similar to that which occurred in Las Tablas de Daimiel National Park, Spain: another locality where wetlands have been virtually destroyed because pumpage for irrigation over the past 20 years has lowered the water table by 20-30 m. Given the importance of understanding the relations of hydrogeologic processes to tile overall ,lyu,-,:t)~:;~,,~' -,~ "l ~f ,,~.~,a,tu~,"' ' and tile importance of ilydrology to the characterization of wetlands and to wetland management, a Iqydrogeology of Wetlands Symposium was held at the 28th international Geological Congress in Washington. DC in July 1989. The purpose of the symposium was to assemble papers describing hydrogeologic studies of wetlands representative of differem geographic regions, wetland types, ~md study appro~.~ches.The ptmers orese~lted at the Symposium ranged ~eographicatly ffonl wetlands in the Arctic to the Subtropics. I)iffcrcnt we|land types included ~'~astaL riverine, depressi~md glacial terrane, and dtmal depressions. Ditl~|~ent study ;q~ploaches included regional syntheses, analyses of groundwater flow systems, wetland-°river interaction~ and geomorphology-vegetation interaction, Of the 14 papers presented orally at the Symposium, the l%llowing ten papers are included in this volume. (I) Woo and Winter present a gener~|l c~7"p~:~rison of the ell~cts of ,~asonal frost trod penmal~rosI on hydrologic pro~zcsses in the Arctic. Subar,;iic~ aml northern Temperate zor~es of North America, (27) C~owe di,~usscs the use of a watcrsb.ed model to simulate the hydrology o,f a prairie lake in glacial terrain in Alberta, Canada, with emphasis on the ground-water component and on the eff}cts of climatic change on the !ake and its contiguous ground-water system. (3) Arndt and
~,N ~| I R N A ' I t O N A ! G~,~OLO!)ICAL CONGRESS
Richardson discuses a prairie wetland in glacial terrane in North Dakota, USA, from the pers~.ective c f soil cl,emistry and hydrology. (4) Doss discusses transient flow of shallow ground water associated with wetlands in a sand dune environment aio~g the sou th shore ,,f Lake Michigan, Indiana, USA. (5) Shedlock, Wilcox, Thoa~pson, and Cohen also discuss the interaction of ground water with wetlands in this same area of dunes in northern Indiana, USA, bvt they include considerable discussion of chemistry as well. (6) Philhps and Shedlock discuss transient ground-water flow and chemistry associated with wetlands and shallow depressions in the coastal peninsula between Chesapeake Bay and the Atlantic Ocean, Delaware, Maryland, and Virginia, USA, (7) Hupp and Ba~emore discuss the effects of sedimentation on riverine wetlands in Tennessee, USA. (8) Schot and Wassen discuss ground-water flow and chemistry associated with wetlands in central Netherlands. (9) Bernaldez, Benayas, and Martinez discuss the effect of ground-water development on the ecology (largely botanical) of wetlands in the Douro Basin, Spain. (10) Snso and Llamas discuss the effect of groundwater development on wetlands in the coa~;tal Donfina National Park region, southwestern Spain. Thomas C. Winter U.S. Geological Survey, Box 25046, Mail Stop 413 Dem,er Federal Center, Denver, CO 80z2~, ~ " USA
M. Ramon Llamas Fa~.ultad de Ciencias Geologicas, Universidad Complutei~se, 28040 Madrid, Spain
l
[21
Introduction to the 28th International Geological Congress Symposium on the Hydrogeology of Wetlands Wetlands are hydrologic features that occur in physiographic and climatic settings that favor the accut~ulation, or retention, of surface water and (or) soil water, Depending oll their physiographic position in the landscape and the climate of tile setting, wedands interact in varying amounts with all componenls of the hydrologic sy~teln; atmospheric water, surface water, and ground water. The terrestrial wa~cr components, ground water and surface water, are controlled largely by geologic characteristics such as land-surface slope, permeability of soils, and hy~raulic characteristics of the underlying geologic framework. Depending on the~e terrestrial features as well as climate, some landscapes contain extensive wettxnds and others contain only a few widely scattered wetlands. It is increasingly being recognized that understanding the hydrologic !;=nctions of wetlands is fundamental to wlderstanding the chemical and biological characteristics of wetlands. I'urthevnore, it is also recognized that the effectiveness of many wetland-management practices is limited because of inadequate understanding of the basic hydrologic processes associated with the wide variety of wetland types. For ~xample, it is commonly thought that surface water is the primary source of t~..rrestrial wa~er input to wetlands; yet, many wetlands are primarily ground-water discharge features, and the persistence el" the wetness is the result of a re!~tively stable influx of ground water throughom changing seasonal and a~ auai climatic cycles. Construction of wetlands to replace destroyed wetland::; can be successful only if the ceplacement wetland has the same hlvdrogeologic and climatic setting as the destroyed wetland. For example, th~ replacement of a wetland that is dependent on ground waIer fc,r its water and chemical inlc~ut needu to be located in a similar ground-wa'.er discharge area. It would be eb'-urd to construct a ground-water rechar:;e-type wetland in a ground-wa~:er discharge area, or conversely, to construct a ground*water discharge-type wetiand in a ground-water recharge area, and expect the constructed wetland -.':obe an exact replacement for the natural wetland. Many water-development, !and-sLrfaec development, and landscapemanagement practices can nit;eel lhe hydrology of wetlands in varying ways and deglecs. These practices include weather modification, storage of surface f~}22~16941931506.00 ~,ci19'-)3~,-- ElsevierSciencePublishers B.V. All righls reserved
2
| t : W|N1ER AND Nt R i,I AMAS
water, drainage of sure)ice water and soil water, urbar~ization such as paving and sewering, road building, changes in land use, and alteration of plant communities. In addition, a number of studies have suggt~sted thal tile development of ground-water resources could have a prc,lkmnd effect on groundwater flow syslems associated with wetlands, and theretbre, on the wetlands thenlselves. Such concerns are commonly voiced in developed semiarid countries, where intensive ground-water extraction is relatively recent. In ott,,er countries that have similar development, bm where ground-water use began well before the ecological movement, wellands may have completely disappeared without public concern: therelk~re, the literature contains few well-documented cases of the effect of ground-water development on wetlands. However, the paper by Suso and Llamas (this issue) discusses the strong relation between the hydrogeologic system and the ecosystems of Donana National Park, Spain, which is considered to be the most ecologically important remaining wetland in soulhern Ezlrope. According to the paper, ground-water pumpage for a nearby irrigation project may cause the destruction of wetlands in Don~ina National Park similar to that which occurred in Las Tablas de Daimiel National Park, Spain: another locality where wetlands have been virtually destroyed because pumpage for irrigation over the past 20 years has lowered the water table by 20-30 m. Given the importance of understanding the relations of hydrogeologic processes to tile overall ,lyu,-,:t)~:;~,,~' -,~ "l ~f ,,~.~,a,tu~,"' ' and tile importance of ilydrology to the characterization of wetlands and to wetland management, a Iqydrogeology of Wetlands Symposium was held at the 28th international Geological Congress in Washington. DC in July 1989. The purpose of the symposium was to assemble papers describing hydrogeologic studies of wetlands representative of differem geographic regions, wetland types, ~md study appro~.~ches.The ptmers orese~lted at the Symposium ranged ~eographicatly ffonl wetlands in the Arctic to the Subtropics. I)iffcrcnt we|land types included ~'~astaL riverine, depressi~md glacial terrane, and dtmal depressions. Ditl~|~ent study ;q~ploaches included regional syntheses, analyses of groundwater flow systems, wetland-°river interaction~ and geomorphology-vegetation interaction, Of the 14 papers presented orally at the Symposium, the l%llowing ten papers are included in this volume. (I) Woo and Winter present a gener~|l c~7"p~:~rison of the ell~cts of ,~asonal frost trod penmal~rosI on hydrologic pro~zcsses in the Arctic. Subar,;iic~ aml northern Temperate zor~es of North America, (27) C~owe di,~usscs the use of a watcrsb.ed model to simulate the hydrology o,f a prairie lake in glacial terrain in Alberta, Canada, with emphasis on the ground-water component and on the eff}cts of climatic change on the !ake and its contiguous ground-water system. (3) Arndt and
~,N ~| I R N A ' I t O N A ! G~,~OLO!)ICAL CONGRESS
Richardson discuses a prairie wetland in glacial terrane in North Dakota, USA, from the pers~.ective c f soil cl,emistry and hydrology. (4) Doss discusses transient flow of shallow ground water associated with wetlands in a sand dune environment aio~g the sou th shore ,,f Lake Michigan, Indiana, USA. (5) Shedlock, Wilcox, Thoa~pson, and Cohen also discuss the interaction of ground water with wetlands in this same area of dunes in northern Indiana, USA, bvt they include considerable discussion of chemistry as well. (6) Philhps and Shedlock discuss transient ground-water flow and chemistry associated with wetlands and shallow depressions in the coastal peninsula between Chesapeake Bay and the Atlantic Ocean, Delaware, Maryland, and Virginia, USA, (7) Hupp and Ba~emore discuss the effects of sedimentation on riverine wetlands in Tennessee, USA. (8) Schot and Wassen discuss ground-water flow and chemistry associated with wetlands in central Netherlands. (9) Bernaldez, Benayas, and Martinez discuss the effect of ground-water development on the ecology (largely botanical) of wetlands in the Douro Basin, Spain. (10) Snso and Llamas discuss the effect of groundwater development on wetlands in the coa~;tal Donfina National Park region, southwestern Spain. Thomas C. Winter U.S. Geological Survey, Box 25046, Mail Stop 413 Dem,er Federal Center, Denver, CO 80z2~, ~ " USA
M. Ramon Llamas Fa~.ultad de Ciencias Geologicas, Universidad Complutei~se, 28040 Madrid, Spain