Opportunities in the Hydrologic Sciences (1991) / Chapter Skim
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4. Scientific Issues of Data Collection, Distribution, and Analysis
4. Scientific Issues of Data Collection, Distribution, and Analysis
Pages 214-274
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From page 214... ...
In the history of the hydrologic sciences as in other sciences, most of the significant advances have resulted from new measurements, yet today there is a schism between data collectors and analysts. The pioneers of modern hydrology were active observers and measurers, yet now designing and executing data collection programs, as distinct from experiments carried out in a field setting with a specific research question in mind, are too often viewed as mundane or routine.
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From page 215... ...
Some of the current uncertainties in our knowledge of the hydrologic cycle require better understanding of hydrologic processes, but progress in the hydrologic sciences will also depend on improved methods for collecting hydrologic data, more complete and better-organized archives of already-available information, and better mechanisms for distribution and exchange of data, particularly in developing countries and in the international arena. This chapter describes some requirements for and characteristics of hydrologic data, assesses the current hydrologic data base, and then discusses some opportunities to improve hydrologic data and their use.
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From page 216... ...
216 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES :~:~i~y~nR~o~Lo~G~1c~l~MpL~l~cAT~l~oNs~ OF:~AL~W AlC~M~I~r~Qi~:~:~:~:~ :~ : ~ :~:~:~: ~~:~:::: ~ ~ ~ ~ ~ ~~ ~~ ~~ ~~ 0 :: ~ ~ : ~ ~ ~:~:~ :: ~:~ :~ : ~ ~ :~: :::: : ~~ ~ ~~::~ :~ ~ ~ ~::~: ::: ~ :~: ~ ~ F~ : T:~ :~:~c u~rlng~t 1~e:~spr~l~n~g:~:~montus~ot;;~Ap~r~i~ A l~a~gh~::~J~u~:n~e:.~:~:~The~ ~:net~:~res~u~l~t::~ot~ An - :~:~::4::~::::: ~::~ :::::: :::: ::: :::~:::::~t: ~ ~ ~~ ~~ ~~ ~~ ~ ~~ ~~ ~ ~ ~~. ~n~£reas~e~ ~:~1~n~g~ nodal If::: tem~p~e~r:a:tu~re~wo~u~ tic ~:~:~be~a~ ~~d~ec~re~a~se~:~:~i~n~ stream flow ~:~d~u~r:~i~n~g~ :~ :: ~: :~:~ :~: ~: ~ ~ ~ ~ ~: ~ ~:~: ::~: :~ ~ ~ ~:::~:~::~::~: :~ ~ ~ ~:: ~: ::: ::~: ~: ~ ~ ~ ~ :~:~ :~:~ ::~:~ ~ ~:: ~ ~r:~ ~: ~:: ~-~ ~ :~ ~ ~: ~:~ ~: ~:~:~:: ~ ~ ~ ~ : : ~ ~ ~ ~ ~ : ~ t n e ~ ~ ~ ~ n o ~ r m a ~ : l ~ ~ ~ ~ : ~ s ~ n ~ o w m e I ~ ~ t ~ r u ~ ~ n ~ r ~ ~ : ~ ~ ~ o ~ n ~ t h ~ s ~ ~ ~ ~ ~ o r ~ ~ ~ n e : ~ ~ ~ ~ ~ s p ~ r !
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From page 217... ...
Technical and analytical innovations are necessary to overcome the paucity of useful hydrologic data now being collected and collated. To better characterize the hydrologic cycle requires data in several categories, and the choice of what to measure and where and when to measure influences what hydrologic questions we can investigate.
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From page 218... ...
_ OPPORTUNITIES IN THE HYDROLOGIC SCIENCES ~ 25 ._ 10 , c~~~..o....~.~- ~cl ~ 0 ~ - 5 80 82 84 86 88 ~ 6 Yea r 50 40 ~ ~ ·_ ~ ~,.,~ e Go Lo,.,,.
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From page 219... ...
How much comes from Antarctica and Greenland, from thermal expansion of the ocean waters, from shrinking alpine glaciers, and from depleted ground water reservoirs? Data are needed at a variety of scales, and the spatial and temporal scales of available data restrict the questions that can be investigated.
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From page 220... ...
design data collection programs that will allow the study of theoretical constructs, described in Chapter 3, to structurally link the fluctuations at different scales. Need to Develop Accurate Hydrologic Data Bases to Improve Scientific Understanding Detection of hydrologic change requires a committed, international, long-term effort and requires also that the data meet rigorous standards for accuracy.
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From page 221... ...
Historically, the major providers of funding for hydrologic data collection have expected that the resulting data would be useful in setting water policies, developing water resources plans, designing water resources systems, operating the structures that make up such systems, and monitoring the management of water resources. Increased hydrologic understanding can and does contribute to improved information for these utilitarian purposes, but the design of hydrologic data networks seldom has as a primary objective the betterment of basic hydrologic understanding.
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From page 222... ...
Two general areas for which long-term hydrologic data are specifically needed are discussed briefly in the remainder of this section, but these examples are not meant to be exclusive or exhaustive. Understanding Hydrologic Behavior and Hydrologic Change Long-term data are required to understand the basic hydrologic behavior of natural landscape units.
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From page 223... ...
Because they are infrequent in occurrence, they are poorly represented in all but the longest hydrologic records; only a few data sets contain enough extreme events to allow a precise estimation of their return periods. Moreover, the dynamics of extreme events are hard to measure; stage versus discharge relationships for gaging stations are usually not calibrated for high stages, and scouring of the channel during such flows makes extrapolation of rating curves for lower stages prone to error.
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From page 224... ...
224 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES :: W~ER~RESOUR(:ES~IAGEMENT~i~ i ~~ A A ~~ ~ A i ~~:~ ~~ ~~. H:u~nd~reds~of~bi I lilions~ot Eli den l~ars~ha~tei~b~et~:nikested :~s~~nce ~ lain i i I: ~~ ~ ter Or: ~ ~ ~~sta~ em: :~ ~~£~ hi.
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From page 225... ...
This information substantially altered the interpretation and implications of the 1985-1986 drought, showing it to be a much more common event than it was first considered. Need to Collect Data Worldwide to Address Global Hydrologic Issues Useful hydrologic data representing processes at the gIobal scale are sparse.
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From page 226... ...
A fundamental block to progress in using most hydrologic data is our poor knowledge of how to interpolate between measurement points. For example, depths and water equivalences of a snowpack are measured at many snow courses in cold regions, but it is only possible to use these data as crude estimates of the water content of a regional or basin-wide snowpack.
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From page 227... ...
Cummings 18. Lake Pillsbury FIGURE 4.2 Rain gages in the Eel River basin at Scotia, California.
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From page 228... ...
Therefore, government agencies and granting agencies need to be able rapidly to mount coordinated field studies to collect data when such transient processes occur. Collection and Archiving of Selected Water Samples The archiving of selected water samples will allow better analysis of chemical and biological changes in aquatic habitats.
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From page 229... ...
STATUS OF HYDROLOGIC DATA Knowledge of the distributions in space and time of water, solutes, and sediments is needed for investigation of scientific questions,
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From page 230... ...
Our knowledge of the frequencies of extreme events is usually uncertain. Availability of Hydrologic Measurements Hydrologic data networks are best developed in the humid-temperate, mid-latitude, industrial ized nations.
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From page 231... ...
Complete analysis of water for all common and exotic solutes is expensive, but for water used for human consumption and industrial processes, such analysis is becoming more necessary. Contamination of surface water and, even more so, ground water can render resources permanently unusable.
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From page 232... ...
232 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES ~~ ~~ ~) l~l;OG~1~ 5~1~—E W~ERSH~S~: On ctr0:m~ smoker ~~a~l:~5W~ ~ ~~ ~ ~ ~ ~ ~ .
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From page 233... ...
As with other hydrologic data, coverage is poorest in arid, semiarid, tropical, and highland regions and over the oceans. Like many other hydrologic parameters, rainfall is highly variable in time and space.
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From page 234... ...
234 1.5— en- 1.2 UJ , Lo en ~ ~ ~ 0.6 Li En oh ~ 6 en 0.9 0.3 o OPPORTUNITIES IN THE HYDROLOGIC SCIENCES 68 78.
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From page 235... ...
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~~ ~~ ~ ~ ~~ ~ ~ ;~ ~~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~~ ~ ~ ~~ c'om ma` or: ic~ions~:Mt Rose ~ samp ers~ar~ ~:th~ei~r;~mar~y~: deri~va:ti:ves~: are~:sti~l l ~ ~ ~ ~ ~ ~ ~ ~~ ~ ~ ~~ ~ :~ ~ ~ ~ i~ ~ ~ ~ ~ ~ ~ ~ :? ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~:~e~ the I~m~to~ls~of~:snow~and~::i~c;ol lection;~today.~:~ , : ~ :: I: :: ::: :: :~ if:: I: ~ :~: :: : :::: : I: Snow Accumulation and Ablation Snow accumulates as a seasonal cover before it melts to produce water for runoff and ground water recharge.
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From page 236... ...
From the soil, the moisture will either be returned to the atmosphere, temporarily stored in vegetation, or percolated to the saturated zone. Information about soil moisture and its spatial distribution would be of great value in delineating the dynamic nature of hydrologic processes, but except in experimental basins, soil moisture is never measured routinely, and data on its spatial variation are extremely scarce.
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From page 237... ...
In regions of sparse population or in areas without significant potential for ground water supplies, background data are scarce. On a continental scale, no inventory exists to define the extent and quality of the total volume of subsurface water in storage.
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From page 238... ...
Much of the work in the large-scale, coordinated field experiments such as HAPEX, FIFE, and GEWEX addresses this question of the measurement of evapotranspiration over the spatial scales of large drainage basins. Fluxes of Energy In spite of the fundamental influence that the processes of surface energy exchange have on the hydrology and climate of the earth, data required to estimate the energy fluxes from the land surface are usually available only for areas where intensive field experiments are under way.
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From page 239... ...
Therefore we need information on the exchange of solar and thermal-infrared radiation, latent and sensible heat, and heat flux into or out from the soil or snow. A major influence on the atmospheric circulation and the distribution of precipitation is the distribution of surface heat flux into the atmosphere, whose estimation requires knowledge of the spatial distribution of surface temperature.
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From page 240... ...
Topography Examination of hydrologic processes also requires other information about the surface and subsurface of the earth. Among these, perhaps the most important is topography.
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From page 241... ...
. , , ~ _ , clata Wlth tine spatial resolution needed tor accurate calculation ot slopes over individual drainage basins, but more widely spaced elevation measurements accurate to within a few centimeters.
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From page 242... ...
Satellite measurements of forest clearing can be incorporated into large-scale hydrologic models. Subsurface Information Characterization of a ground water reservoir requires data on the extent, thickness, and structure of the geological units at and below the ground surface; on the hydraulic properties of each of the geological units; on the depth to the water table; on the chemical character of dissolved solutes within each unit; and on the areal distribution of ground water recharge.
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From page 243... ...
SOME OPPORTUNITIES TO IMPROVE HYDROLOGIC DATA Coordinated Experiments Hydrologic models and field measurements in a coordinated program are neecled to obtain a detailed understanding of the energy and water cycle at scales beyond that of the field plot. Large-scale field experiments, combining satellite and extensive in situ measurements, are a means to verify large-scale hydrologic models and validate spatially extensive observations.
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From page 244... ...
New opportunities have arisen as a result of developments in low-cost electronic instrumentation, computer technology for handling large data sets, and remote sensing from satellites and aircraft for observations with appropriate spatial scales. One stream of activity has developed from the realization that simulations of the earth's climate using general circulation models (GCMs)
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From page 245... ...
The First ISLSCP Field Experiment (FIFE) marked the initial phase of an experimental effort envisioned to accomplish these goals.
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From page 247... ...
/ I \\ in, FIGURE 4.7 Range of scales addressed in First ISLSCP Field Experiment (FIFE)
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From page 248... ...
248 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES I~;~;~:~:~:~T~H~E:~ATI~O~NA ~ O M Pi ~~ ~~:~ ~~ ~~ ~~:~-~I~n~e:~c~u~i:r~n~t~state~of~und~ - often teorol~ ~ ~~ If- ~~ ~ ~~ ~: ~~ ~~ ~~ ~ ~ ~~ ~ ~~ ~ ~ ~~ ~~ . ~~: ~ ~~ ~ ~~ ~ :~: ~ ~ ~rece~nt~yea~s~h That a ~~r:~e-:~:~five-d;a~y ~~ou~troo~ki~tor~a~su~n~ny~w~eel~n~d~:~:~ wet:~:p~;:s~ - legato ~~be::~:~And~yet,~ ~ - rtiterm: :~ pm~$lK~n~p~r~i~o:~n~a~n~liswere~ - atlNe~r~:~::~eve~n~ts~::~:~al~Q:ugli~:~:~m~o~re~:~:~:~: Scan sty l~i: ~~:~to~t~:~:b~l:~i~:~a~n:d ~ ersatz ~ar~:~l~ - eq~:;~t~h~is~:e~n~l~:ng~Q~cca~s~:l~o~n~a;~l~t~y~ ~be~d:~e~l~e~s~t~h~at~:~ca~n~:~a~n~d:~:~ :~:d:~o ~:~c~a~s~e~t~g~fl~a~fiQod~s~.~ ~~l~s~s~::~d~ram~ati;:dJ~li~ - c~:~ra~:ns~: May:; ~~nlY~:~i~h~:~, ~ ~~ ~~i~e~p~s~h~t~h~ey~ IS Carried o:~:t~o~u~l~oo~r~a£f~i~v~i~i~=c~ ~~r~:~ ~ ;~:~ ~ :~:~;~:~v:y~i~ rives Nan ~~::~ex~pl a~:l~n~:~th~l~s~ state: ~ ~f~:~a~ if pa id ~ In As: so ~~ id Olin flu n d 4 ;~5y~eratiorial~and~ ReQearch~logy~ ( ~~P~w~;~l;~l~be~a~n~:~;i~m~porta~nt~::~ - t~:th~e~1~9~9~0s.~:~We~h~a~v~e ~~:~im~p~rovre~d~:~ ~ ~~ ~~ ~ ~~ ~.~.~ ~ ~~: ~.~ ~ :~ ~ ~ ~~ ~ :~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~ ~~ ~ ~ :~ l ~ ~ ~ b ~ e c a u s e ~ ~ ~ o ~ i ~ r ~ : ~ ~ ~ ~ ~ n ~ ~ ~ ~ ~ ~ ~ s t a n ~ i n ~ g : o b s e r v a e ~ n a ~ I :a~;~:ies,~pg~t - vial ~~:~apa~l~tie~s~are:~e~q - ~~to~t~h~e~k~:~Th~ ~: ~ ~ ~ ~ , ~ i.
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From page 249... ...
DATA COLLECTION, DISTRIBUTION, AND ANALYSIS 249 ~~;rharader`:ratlon~ by ~~r~emote~sens~i~n~gt~d~u~ri~n~th~e~ne~xt~d~ec~an~e~.~ multaneous observations from aircraft and at numerous ground stations, and by atmospheric soundings of different types. As international efforts both HAPEX-MOBILHY and FIFE posed severe and formidable problems of logistics and coordination.
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From page 250... ...
The hydrologic sciences, much like the rest of modern earth science, are starting to examine interactions among the different terrestrial components at all temporal and spatial scales. Such an inclusive perspective requires an integrated data collection program, and remote sensing is an essential component.
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From page 251... ...
Examples include anthropogenic damage to vegetation, which first appears in patches; forest clearing, which dramatically affects evaporation and carbon cycling, and which in the tropics occurs in small, noncontiguous areas; land use change and desertification, where boundaries may move only short distances; alpine snow and ice, where spatial coverage may be small but where large volumes of water are stored; changes in permafrost and buried ice lenses caused by atmospheric warming; and changes in the extent of freshwater and saltwater marshes caused by changes in the water table height or sea level. Remote Sensing of Hydrologic Parameters Some important hydrologic variables can be measured by remote sensing.
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From page 252... ...
252 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES ~~ ~~;~:~I:QWS:~BAlik~N:: ~~ :~ ~ ~:~f1~q9~_1~q~:~::~ ~~ ~~ ~~ ~~:~ Also ~me~of~u~s:~:~struggl<~ tbroug~h~li~ to find ~::the~right::~ career path,: ~~whiJe~ mbers~take~:a~:~random~step~t~t~s~ets~a~:route~:early. ~~rs~J.~ :~ ~~Ba~tta~ew~;~:~ - :~i~i~:~so~n:~Austria:n~ i mm inrn~nic ~ ~;~rh~i~u=:r1~ Hi cat :: : : : ::~:: :~: ~ : :: :~ :::: :: :: : ::: : :: : :: : i: ~:~r~own~:as~:~ a n~eteoro~iog~ist~bec:ause:~:~an :~Army ~~r~ruiti~r~g:~ ~poster.
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From page 253... ...
DATA COLLECTION, DISTRIBUTION, AND ANALYSIS 253 ~~:~:a~sL rye.
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From page 254... ...
will improve the knowledge of rainfall over important tropical areas of the earth where data are scarce. One important focus of these future missions is the creation of hydrologic data products.
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From page 255... ...
1. Universities must recognize that students in the diverse array of disciplines that analyze the earth's hydrologic processes will need to be trained in remote sensing, as well as in the conventional supporting subjects of physics, chemistry, mathematics, and computer science.
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From page 256... ...
5. Hydrologic data products must be defined and processed from raw remote sensing data, so that the information will be available to a wider variety of scientists instead of being restricted to those with expertise in remote sensing.
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From page 257... ...
Basic research is needed to better understand the relationship between the recorded signal and the hydrogeologic properties of the subsurface. If the potential of these two methods is realized, they will herald a new era in detailed mapping of subsurface properties relevant to hydrologic processes.
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From page 258... ...
Incorporating isotopic data with new advances in geochemical and hydrologic modeling promises considerable potential for gaining new insights into subsurface hydrologic processes and their link to processes occurring on the land surface. During the period from 1957 to 1963 massive amounts of tritium were introduced into the upper atmosphere from the testing of thermonuclear weapons.
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From page 259... ...
Paleahydrology and Long-Term Records Paleohydrologic information can extend the time series of hydrologic data beyond the period of record and thereby give us a better picture of hydrologic trencis and the statistical distribution of phenomena.
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From page 260... ...
Traditional monitoring is useful in many applications, but new methodologies or increased efforts made with established procedures are necessary to produce information about long-term effects of climatic variation on hydrology. A current opportunity to improve hydrologic data is the development of new long-term records of climatic-hydrologic variation.
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From page 261... ...
The geomorphic-geologic sources of information, such as fluvial flood deposits, are sporadic in distribution, as are paleosols, varved sediments, and paleolimnological opportunities. In areas where proxy paleohydrologic indicators are absent, geochemical indicators, including isotopic analyses, can potentially determine sources, ages, and histories of ground water.
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From page 262... ...
262 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES TEMPORAL RESOLUTION ANNUAL BANDS ~ RADIOMETRIC 0-2 % ERROR ORBITAL TUNING - 5-10 % ERROR 2-3000 YEAR ERROR SOURCES OF ~ PALEOCLIMATIC ~ ~ ~ HISTORICAL DATA / _ — CORALS ICE CORE VARVES . GLACIER MOVEMENT ~ ~ |
From page 263... ...
Such exercises should validate the model mechanisms and concepts and also estimate potential changes in the global hydrologic cycle. The extent of the normally recorded information is too limited in time and space for such validation.
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From page 264... ...
264 o ~ LL Z > cn ~ '_ Z Z ~ c-)
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From page 265... ...
Although it has been used successfully in many areas of the world, there are now more opportunities than accomplishments in paleohydrology. Data Accessibility and Management Advances in the hydrologic sciences depend on how well investigators can integrate reliable, ~arge-scale, ~ong-term data sets.
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From page 266... ...
Data Storage and Access Optical disks and compact disks have become an attractive alternative to traditional magnetic tape or disk storage media, because they offer the capacity and security necessary for hydrologic archives, and because multiple copies of large archives can be made cheaply. For example, the entire daily stream gaging record of all gaging stations for one year is stored on optical disks for such countries as the United States and New Zealand.
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From page 267... ...
DATA COLLECTION, DISTRIBUTION, AND ANALYSIS 267 This is no small effort: it requires direction on a day-to-day basis by active scientists. In particular, for large projects, the role of a project information scientist must be recognized as critical and must be rewarded appropriately.
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From page 268... ...
If these studies are to be useful to understand the causes of observed conditions, and thus provide a foundation for cost-effective amelioration of water quality problems, they must address scientific principles as well as practical ones. Water Quality Monitoring and Assessment Data for water quality monitoring and assessment may be divided into three types:
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From page 269... ...
However, managers of data collection programs for all three types of data need to become more aware of ways that data from individual programs can be made more useful for addressing issues that are beyond the immediate program objectives. These include: · the need to collect important ancillary data, to place the water quality data in the context of the natural and cultural setting; · the need to carefully document sample collection and laboratory analysis procedures; and · the need to archive the raw data in easy-to-access computer files.
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From page 270... ...
Instead, innovative designs must be developed that fully use the existing understanding of the physical, chemical, and biological processes that determine water quality. A major deficiency in environmental data collection programs has been the inadequate development of information useful for defining long-term trends in water quality.
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From page 271... ...
Physical and chemical properties of water may vary rapidly, and intermittent or infrequent "grab" samples may give misleading indications of prevailing water quality. The native biota may be better indicators of water quality and human effects because of their prolonged exposure, integrated response, and differing sensitivity to all the varying conditions of their environment.
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From page 272... ...
The occurrence of one type of effect, sewage contamination, has traditionally been determined using as tracers microorganisms indigenous to the gut of humans and other warm-blooded animals. Bacterial density in laboratory cultures inoculated with water samples is interpreted to show the degree of fecal contamination and the potential occurrence of associated human pathogens.
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From page 273... ...
Pop~abo~ of orgasms are ~tendonaDy added by management programs and u~nhonaDy affected by natural and anthropogenic environmental effects These and other issues often require studies on large spatial and temporal scales. Saw sages Cold be ~o~ora~d Ho national Ed ~temabonal mater quality monitoring systems to provide the means to evaluate Ed Prove Completely developed but potendaNy valuable biological methods for understanding the organization and functioning of hydrologic systems.
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From page 274... ...
1989. Tritium as an indicator of recharge and dispersion in a ground water system in central Ontario.
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