U.K. KARST HYDROLOGICAL
PROGRAMME (Devon)

1.  General Introduction :

The Devon Karst Research Society.
ACTIVITIES (U.K.)
.
U.K. KARST HYDROLOGICAL PROGRAMME (Devon).
1.  General Introduction :
.updated 09 April 2007. and under reconstruction.
Webpage Contents :
Sect.1..General Introduction (opposite).
Sect.2..Details for Obtaining Karst Hydrometric Data.
Sect.3.Details for Obtaining Karst Water Quality Data.
Sect.4..Establishing Karst Underground Flowlines in Devon.
Sect.5. Further Information.

Click on the underlined Links.above to move
down to the Sections quickly.


Views of Karst Ponors and Sinking Streams
in South Devon :

1. Karst Ponor Systematic No. KS1.

The Society's U.K. Karst Hydrological Programme was begun in 1976 initially to monitor pollution levels in the cave water within the Baker's Pit / Reed's Cave System in the Church Hill Karst at Buckfastleigh, Devon. It gradually developed over the following 2 years with the addition of the determination of subterranean flow-lines and then the determination of carbonate chemistry of the cave waters.
The Society's UK Karst Hydrological Programme was at its peak level of activity around the early to mid 1990's and has declined since then, due to the change in emphasis of the Science Programmes. Sadly, a long Data Series was ended in 1998 in the Denbury Karst Hydrogeological Unit, in the Denbury Master Cave and its associated catchments. Although the U.K. Hydrological Programme was due for a renewal of activity in 2004., resulting from another change in emphasis of the Science Programme and also in order to support the International Karst Hydrological Programme, this has not happened due to the pending change in status of the Society.

The U.K. Programme has greatly benefited from the experiences of the Society's International Karst Hydrological Programme, especially that undertaken in Hungary, Slovakia and Bosnia & Herzegovina.

OVERVIEW :
The Society's U.K Karst Hydrological Programme (hereinafter UK-KHP) is a continuously running core-programme which, on the one hand, is long-term monitoring karst water quality and quantity and on the other hand, is correlating data in an attempt to better understand the dynamism and mechanism of the Karst Process in various karst areas of the U.K.
The resultant information-databases receive data from two types of activities. The first type includes projects specifically devised and implemented to purposely generate such information. For instance, an example would be the design and construction of a hydrometric weir for installation at a karst ponor or spring. The second type of activity is where data is generated or collected during the course of undertaking other work such as, for example, when visiting a cave or karst area to undertake conservation work.

The Society's U.K. Karst Hydrological Database has been receiving data from such activities since 1974. The only continuous data-series obtained during that period was for the Denbury Master Cave and its associated karst and catchments. The data-series ran continuously from 1987 for a period of 11 years but was regettably terminated in 1998.

The Karst Hydrological Database is also useful for time-based trend-analysis for environmental evaluation projects and in this regard, is especially useful for tracking the effects of pollution. The webpages on this aspect of the Society's activities detail examples of specific projects, together with methods used and the problems encountered.
From experience gained in processing karst hydrological field data from the Society's projects in Bosnia & Herzegovina, the U.K. Karst Hydrological Databases are currently being reconstructed into a similar digital format and for the first time, will be published and available in these pages. However, the Links to these Databases will not be made available to non-Members of the Society, insofar as the data is of commercial interest.

The information contained in the Society's Karst Hydrological Database (Devon Section) also contributes to the aim of developing a series of 1 : 2 500 Karst Hydrogeological Maps for the Devon's karst areas.

FIELD-DATA COLLECTION AND INTERPRETATION :
Prior to 1976, experimental work was undertaken to try and assess the best and most practical methods for obtaining reliable and accurate data.
The field data collected since 1976 has been obtained using standardized methods and equipment.

It is interesting to note that during the intervening period between 1976 and now, some of our core methods for field chemical analysis have not changed significantly. Although accurate, reliable and affordable electronic instrumentation is now available to augment the number of parameters we monitor in our field-work, the aspect concerned with obtaining the core carbonate-chemistry values continues to be underpinned by the use of portable wet-chemistry EDTA rapid-titrimetric methodologies. In this aspect alone, we have not been convinced of the application of the currently available electronic instrumentational alternatives, although we are searching for an electronic alternative to the cumbersome wet-chemical method for determining the carbonate-saturation value.
An outline of our methodologies for obtaining karst water physico-chemical field-data can be viewed in the appropriate Section below.

The interpretation of our field-data can be undertaken by applying many different statistical methods, according to what factors are being looked for. One of the obvious uses of some of the data collected from certain sites is that of observing time-based trend-analysis for the effects of pollution. Although pollutants are rarely directly monitored for, the effects of pollutants on the rate of carbonate-dissolution in particular can be clearly seen at those locations which, for example, are in direct hydrological contact with landfill sites.

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U.K. KARST HYDROLOGICAL
PROGRAMME (Devon)
2...Details of Methodologies for Obtaining Karst Hydrometric Field Data in Devon
U.K. KARST HYDROLOGICAL PROGRAMME (Devon).
2...Details of Methodologies for Obtaining Karst Hydrometric Field Data in Devon
and details of Specific Hydrometric Installations in Devon, with Construction & Performance Details.
Views of Karst Resurgence Springs and
Rising Streams in South Devon :

1. Karst Spring Systematic No. K.Res.05.
.

Image 1. The outlet of the Fairwater Karst Risings
at Rydon, Kingsteignton.
(Photo :..B. Lewarne, 17 June 2001)


Image 2...The outlet of the Fairwater Karst Risings
at Rydon, Kingsteignton.
(Photo :..B. Lewarne, 20 March 2003)


Image 3...The upstream artificial lake of "Well Head" submerging the point-source of the Fairwater Karst
Risings at Rydon, Kingsteignton.
(Photo :..B. Lewarne, 17 June 2001)

KARST HYDROMETRICS PROGRAMME :
METHOD FOR DETERMINATION OF WATER VOLUME :
Introduction :
The discharge of a surface stream into a karst sink (ponor) or that of a stream rising from a spring can be measured as the VOLUME of water sinking or emerging respectively, in UNIT TIME.
This value is usually expressed in terms of litres per second ( l sec-1) or, in the case of larger volumes, cubic metres per second ( m3 sec-1 ).
Several established methods for guaging water-volume are available, from which we could chose the most appropriate to suit any particular site and circumstance.
When devising a suitable method for water-volume measurement, the main criteria we have to consider are :-
  • Accuracy of the method;
  • Purchase costs of the measuring apparatus;
  • Installation costs of the apparatus;
  • Maintenance costs;
  • Calibration costs, if any;
  • Locational (site-specific) considerations & limitations / suitability of method;
  • Security and proof against interference and vandalism.
  • Method options available vary from fixed stream-bed flumes and brim-boards to Thin Plate V-notch or Rectangular-notch weirs and associated recording guages and guage-heads.

    Methodology of Direct Measurement :
    It has been found that a large proportion of streams sinking into ponors or rising from karst springs in Devon can be conveniently quantified by accurately measuring the time taken to completely fill a container of known and calibrated volume.

    ..........Q = V
    .................t
    where :
    ..........Q  =..Amount of water in litres / sec. ( litres sec-1)
    ..........V  =..Volume of Container, (litres).
    ........... =..Time taken to fill the container, (seconds).

    So, for many of the ponor sites, it was decided to employ a simple and economical method, whereby a small semi-permanent weir or dam was constructed across the streamway. Into the weir was incorporated a pipe or series of pipes through which the entire flow could pass unhindered into a calibrated container on the downstream side. It was important to ensure that the water always has free-flow, by deciding on large enough pipe diameters to cope with the flow under all conditions. In some locations, British Standard Thin Plate Weirs were also installed.

    Methodology of Indirect Measurement :
    The use of Weirs and Flumes in association with water-feed Canals and Stilling Wells have been and continue to be both acceptable and commonly used methods of determining the Flow Volume. The Stilling Well may be used in conjunction with a fixed Hydrograph device or other measure for recording the water-level upstream of the Weir.
    The Society has had to resort to the construction and installation of British Standard Thin Plate V-notch Weirs and associated infrastructure at various karst spring-heads and ponor sites to evaluate the yield of springs or the point-discharge volumes of water into ponors, where the volume of water is either too great for a Pipe-Weir or where the recording of water volume is being undertaken by a continuously recording hydrograph. Limited details of specific hydrometric installations are in preparation for publication on this Webpage.

    Locations remaining Un-guaged :
    It must be stated that we have not always been able to instal permanent or even semi-permanent hydrometric installations at some important locations which are in private ownership, due either to the lack of permission to do so or to the financial cost involved. One such site is the Fairwater Karst Risings, (Site No. K.Res.05) at Rydon, Kingsteignton, illustrated in the left-side column of this Webpage. This karst hydrological location is of sub-regional importance and contains the vestiges of a previous hydrometric installation from many years ago and of unknown origin. We have an ongoing research requirement to monitor the flow or yield of this considerable karst aquifer, whose output is periodically too large to measure with a standard Multiple-pipe Weir or a Thin Plate Weir. Permission has not been forthcoming for us to install an effective hydrometric device at this important karst hydrological location.
    There are many other examples.

    Constraints of the Land Drainage Act (1991) when installing Hydrometric Weirs in the U.K.
    The construction of installations in or on waterways which cause impoundment, diversion reduction or cessation of flow, is not permitted without licence. This is partly covered in :-

    "Control of flow of watercourses etc. (Prohibition on obstructions etc. in watercourses)
            23.—(1) No person shall—
           (a) erect any mill dam, weir or other like obstruction to the flow of any ordinary watercourse or raise or otherwise alter any such obstruction; or
           (b) erect any culvert that would be likely to affect the flow of any ordinary watercourse or alter any culvert in a manner that would be likely to affect any such flow,
    without the consent in writing of the drainage board concerned."

    When deciding exactly where to construct hydrometric weirs, the Society has had to be very careful in ensuring that the Law is not infringed. Our weir installations are constructed at spring-heads or within ponor features (ie. at the beginning or termination of surface watercourses). The Law does not seem to have any technical regard for such events underground within cave systems!

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    Image 4....A 5-Pipe Weir in use at a Devon Ponor.
    This installation is a Combination Weir.
    (Photo :..B. Lewarne, 17 June 2001)
    DETAILS OF SPECIFIC HYDROMETRIC INSTALLATIONS IN DEVON, with Construction & Performance Details.
    [under construction]

    Pipe Weirs are not only very efficient and convenient installations in their own right for guaging flow volumes, but when used in combination with Thin Plate V-notch Weirs, they can also provide a very useful calibration function for the V-notch weir, where the latter is used for most of the time as the guaging structure. The Society has had occasion to use a combination of Pipe Weirs with other types of Weir to measure a stream flow.
    Thin Plate V-notch Weirs are more complicated devices, both to install and to operate. They are also very expensive to construct and install, when compared with Pipe Weir installations. The advantage with Thin Plate V-notch Weirs is that they can be used in combination with automatic constant-measurement water-level guages (recording hydrographs), installed under specific conditions on the upstream side of the V-notch. The Society has had such installations operating in Devon's Karst.

    1. PIPE WEIRS :
    [under construction]
    When used as the principal flow-measuring device, Pipe weirs do have limitations in functionality and to a certain extent, under certain conditions, these limitations can be meliorated. We would suggest that about 92% of Devon's ponor-ingress streams  and 70% of the egress streams from karst springs are suitable for this type of hydrometric installation. There is an optimum point at which the advantages of the use of multiple-pipe Weirs are outweighed by the use of Thin Plate Weirs or Flumes. The optimum point is determined by prevailing practical conditions and not always necessarily by a mathematical function!
    The simplest Pipe Weir would be a single unit that is incorporated into a stream bed through which the whole flow has to pass and which can be caught in a container of known volume on the downstream side of the Pipe Weir which can be filled in a time that can be easily and accurately measured. Such a simple system has been used on innumerable occasions underground in cave systems, where a temporary structure is easily made and demolished. However, on the surface, more permanent structures have been created at the mouths of ponors or karst springs.
    In Devon, we have constructed such systems, usually with multiple pipes, as part of a ponor melioration scheme, with the Pipe Weir being installed when all other work has been completed.

    2. BRITISH STANDARD THIN PLATE "V"-NOTCH WEIRS :
    [under construction]


     

    Where they can be used, Thin Plate Weirs have distinct operational advantages over the use of Pipe Weirs. They do have limitations and are more needy of maintenance. Unfortunately, the installation of such hydrometric installations is complex and if the device is to perform to specified British Standards of operation to yield reliable data, certain critical constructional parameters must be adhered to, both with the manufacture of the Thin Plate Weir itself and in its installation and operation.
    Owing to the operational criticality of the whole hydrometric installation and the time, costs and labour involved with its construction, very few hydrologically-active karst locations (ponors or karst springs) in Devon are technically suitable to receive such a device or, if they are technically suitable, carry a high risk of attracting unwanted attention and the ensuing vandalism.

    The Society has been able to locate a suitable location for the installation of such devices on private land and well away from unwanted public attention. In one location at a complex karst resurgence spring group, BS V-notch Thin Plate Weirs were employed at the two principal outlets, whilst Pipe Weirs guaged the other outlets associated with the same resurgence group. Further details will be given below.
    For those of a more technical disposition, we shall discuss the practical issues surrounding the design, construction, installation and operation of Thin Plate Weirs at karst locations

    Image 5...(left).
    A British Standard V-notch Thin Plate Weir in use at a Devon Karst Resurgence Spring.
    This installation is a single unit built to guage water output volumes in tandem with adjacent Weirs at the same Resurgence Spring Unit.
    (Photo :..B. Lewarne, 12 January 2002)

    U.K. KARST HYDROLOGICAL
    PROGRAMME (Devon)
    3...Details of Methodologies for Determining
    Karst Water Quality Data in Devon.
    U.K. KARST HYDROLOGICAL PROGRAMME (Devon).
    3...Details of Methodologies for Determining Karst Water Quality Data in Devon.
    DETERMINATION OF KARST WATER QUALITY :
    General Approach :
    The Society recognizes the many potential and actual problems associated with the accurate determination or collection of field data in karst hydrological research programmes. Such problems are particularly prevalent in the determination of karst hydrochemical data. This latter situation is due to the inherent instability of the ionic regimes comprising the fundamental karst process, which do not contribute to a strong and stable hydrochemistry. Indeed, the carbonate / hydrogen-carbonate chemical ionic regime is notoriously unstable, being perpetually subjected to changes as any number of prevailing physical conditions change.
    The Society has long realised that for the purposes of accurately measuring physico-chemical characteristics of karst water which relate directly to the fundamental reactions of the karst process, it is best that such measurements are determined in situ at the location being monitored, whether this happens to be underground or on the surface. Conversely, it is not an acceptable approach to sample such water and to remove it to a location elsewhere for later examination. This latter approach does not necessarily apply to the methodology of the micro-biological examination of such water.

    The practical procedural limitations of extending this essential principal into actual fieldwork conducted onto the karst surface are not so great as the problems to be overcome when extending it underground into cave systems. Since its inception in 1976., the Society has accomplished this feat within its own karst hydrological research programmes, both in the UK and elsewhere, by using an overall optimized methodology of mixed procedures, involving the use of a combination of manually / automatically calibrated electronic methods and wet-chemistry methods, both on the karst surface and deep underground in cave systems.

    The benefits of this are obvious and immediate. Using this approach, our researchers are able to obtain the dynamic values of physico-chemical data relating to karst water quality and data-profiles of complete "surface-to-underground-to-surface" karst water systems, including that in underground locations where values are needed upstream and downstream of waterway-confluences and other locations where different types of water enter the hydrosystem. Thus, the characteristics of underground karst water in situations such as waterfalls, condensation water, percolation water, rimstone and other sinter-pools, can be accurately determined and their effects, singly or in various combinations, can also be measured when they eventually mix with each other and with main cave streams.

    It is obvious that by obtaining data directly from in situ determinations of the dynamic karst process on and within the karst, in scientific terms the results are more valid than relying on the later remote testing of collected samples.

    METHOD-TYPES FOR DETERMINATION OF PHYSICO-CHEMICO CHARACTERISTICS :
    Methodology of Direct Measurement of Water Quality Values :
    The following values are determined directly :-

    ........... dynamic pH..(0.00 -14.00)..direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Glass Electrode and Temperature Probe and with Temperature Compensating Device set at automatic for 25 º C.
    ........... dynamic Electrical Conductivity  ( µS / cm.).direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Conductivity Probe and Temperature Probe.
    ........... dynamic Total Dissolved Solids  (mg / litre)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with TDS Probe and Temperature Probe.
    ........... dynamic Eh Redox Potential  (mV)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Eh Probe and Temperature Probe.
    ........... sample Temperature  ( º Celsius)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Temperature Probe.
    ........... ambient Temperature  ( º Celsius)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Temperature Probe.
    ........... dynamic Dissolved Oxygen  (mg / litre)  direct method using a Palintest PT148 Dissolved Oxygen Meter and Temperature Probe.  (not yet undertaken)
    ........... dynamic Turbidity   (NTU)  direct method using Palintest Micro 900 Turbidimeter. (not yet undertaken)
    .
    ........... dynamic Calcium Hardness  (as mg / litre calcium carbonate)..direct.in situ method by EDTA Titrimetric Complexometry.
    ........... dynamic Magnesium Hardness  (as mg / litre calcium carbonate)  direct.in situ method by EDTA Titrimetric Complexometry or through calculation "by difference".
    ........... dynamic Total Hardness (as mg / litre calcium carbonate)..direct.in situ method by EDTA Titrimetric Complexometry.
    ........... dynamic Carbonate Under-  or Super-Saturation Level (as mg / litre calcium carbonate)..direct.in situ method by EDTA Titrimetric Complexometry.
    .
    ........... total Copper  (mg / litre Cu)  direct method by Palintest tablet count.
    ........... Chlorides  (mg / litre Chloride)  direct method by Palintest tablet count.
    ........... Nitrates  (mg / litre Nitrate)  direct method by Palintest tablet count.
    ........... Phosphates  (mg / litre Phosphate)  direct method by Palintest tablet count.
    ........... Sulphates  (mg / litre Sulphate)  direct method by Palintest tablet count.
    ........... Ammonia  (mg / litre Ammonia)  direct method by Nutrafin reagent drop count test.
    ........... Iron  (mg / litre Iron)  direct method by Nutrafin reagent drop count test.

    Additional qualitative values are likely to be added to the list above in the future
    The analyses using Palintest Tablet Count procedures are now reserved for non-carbonate determinations and it is to be hoped that they will be replaced in due course with more accurate methods.

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    U.K. KARST HYDROLOGICAL
    PROGRAMME (Devon)
    4...Details of Methodologies for Establishing
    Karst Underground Flowlines in Devon.
    U.K. KARST HYDROLOGICAL PROGRAMME (Devon).
    4...Establishing Karst Underground Flowlines in Devon.
    ESTABLISHING KARST UNDERGROUND FLOWLINES IN DEVON :
    This aspect of the Society's work in Devon is on-going. Over the period of the last 31 years, we have undertaken numerous and often extensive exercises to establish underground flowlines either from within cave systems or from ponors to springs. The reasons for doing so have ranged from the purely academic to those of practical necessity as part of the support work of other research projects and has sometimes even been commissioned by others. It is our intention to investigate the flow-direction and underground connections of all of Devon's ponor streams and we have attained much towards achieving that objective.
    Karst underground flowlines should never be viewed as purely 2-dimensional phenomena. The flow-regime characteristics of karst aquifers are inherently ephemeral and ever changing in the 4 dimensions. The flow of water through karst aquifers is always changing with time and with the seasons, in addition to those changes brought about by the occasional internal morphological rearrangements within the aquifer itself.
    To extend this concept of uncertainty into a practical scenario, we have identified the presence of underground bifurcations in the flow directions within some Karst Hydrologeological Units of South Devon. Where they occur, these bifurcated flowlines can simultaneously direct the underground flow in opposite directions and furthermore, they often only occur when the water levels in the karst aquifer are high. Even undertaking repeated tests under differing groundwater conditions through one "hydrological year" of 13 months, may not reveal the full extent of the underground karst flow regimes for many such years, until certain unseen conditions within the bifurcated aquifer are optimal for such results to be obtained. Then there are the questions of flow-through rates and times to be considered!!

    Thus, what at first may be considered to be a simple endeavour to establish a ponor-to-spring underground flow-line may, in actuality, be far more complicated. Therefore, the results of field operations devised to establish underground flowlines in Devon can often be fraught with potential problems of mis-interpretation, if the operations themselves are not prepared, planned and executed thoroughly.
    The cost of undertaking such work can and often is relatively expensive in time, materials and labour. Within the voluntary sector, labour costs are assumed to be free but nevertheless can still be quite demanding in the sheer numbers of field operatives required to oversee such operations in certain areas. Such work is always a balance between efficiency of data acquisition and the investment level of resources.
    It should, therefore, be generally understood that the results of such tests, especially when repeated at the same locations over many years, have an inherent commercial value and for this reason, we are reluctant to offer specific details about our results. This situation will not continue forever and we have plans to formally publish some of the accumulated data in the future.

    Some of the early dye-testing experiments that the Society has undertaken at the beginning of the past 31 year period, have been controversial because of the locations selected for the experiments and the highly visible results obtained!
    However, as our expertise has grown, most of the dye testing undertaken from the mid 1980's onward has not yielded highly visible results. This development has correspondingly resulted in the use of less dye, costing us less money and with no negative public relations issues to have to address. The development of such skills have been as a direct result of experiences with professional hydrogeologists in Eastern Europe.

    In the meantime, we are now digitally preparing one or two examples of our Reports for Web-publishing. As and when these Reports are digitized, they will be made available via the passworded-access Link in the Section below.

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    5.  FURTHER INFORMATION :
    Below are the Passworded-access Links which, when they become active, will lead authorized users to further information.
    • UK KHP (Devon Section) Combined Physico-Chemical & Hydrometric Database.

    • (Passworded for Authorized Access only).  (ready for access).
    • UK KHP (Devon Section) Hydrometric Database.

    • (Passworded for Authorized Access only).  (not yet active).
    • Details of Established Karst Underground Flowlines in Devon.

    • (Passworded for Authorized Access only). (not yet active).
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