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MONOGRAPHS OF THE BOREAL ENVIRONMENT RESEARCH 12 Markku Puupponen Structural development of the Finnish national hydrometric monitoring network Yhteenveto: Suomen valtakunnallisen hydrometrisen seurantaverkon rakenteellinen kehittäminen FINNISH ENVIRONMENT INSTITUTE, FINLAND Helsinki 1998 ISSN 1239-1875 ISBN 952-11-0329-9 Tammer-Paino Oy Tampere 1998 Contents List of terms and abbreviations 5 List of symbols 1 LIILIUUUCLIUII 11 1.1 International developments of hydrological network design 11 1.2 Development of hydrometric monitoring in Finland 12 1.3 Needs to restructure monitoring at FHNS 14 1.4 Aims of the study 15 1.5 Steps of the study 15 2 Role of the national hydrometric network 16 2.1 Model of network characteristics and monitoring objectives 16 2.1.1 Monitoring purposes and monitoring objectives 16 2.1.2 Network characteristics 16 2.2 Estimates of data needs and related monitoring practices 18 2.2.1 General approach 18 2.2.2 Weights of monitoring purposes 20 2.2.3 Weights of monitoring practices 21 2.2.4 Results of the stochastic simulation 22 2.2.5 Overall assessment of the procedure 22 3 Evaluation of the original network 23 3.1 General approach 23 3.2 Decision rules for station classification by objective 23 3.3 Results of classification by objective 26 3.4 Further evaluations 26 3.5 Network structure after the evaluation 27 4 Studies of spatial estimation stations 28 4.1 Cluster analysis 28 4.1.1 Method 28 4.1.2 Selected stations and flow characteristics 29 4.1.3 General results 31 4.1.4 Individual stations and cluster formation 36 4.2 NAUGLS 36 4.2.1 Method 36 4.2.2 Selected stations 38 4.2.3 Regression studies 39 4.2.4 Results of the preliminary regression experiments 41 4.2.5 Stationarity of the discharge time series 44 4.2.6 GLS regression procedure 46 4.2.7 NAUGLS ranking procedure 48 4.3 Decisions about the future network 50 4.3.1 International decision frameworks 50 4.3.2 Evaluation procedure of the present study 51 4.3.3 Accepted and rejected stations 53 5 The reduced network nnd its cost-efficiency 53 5.1 Changes in the extent of the network during the programme 53 5.2 Comparison between the original and reduced network 53 5.3 Cost analysis 56 5.3.1 General principles 56 5.3.2 Cost calculations 57 5.3.3 Comparison of total costs 57 5.4 Cost-efficiency 58 5.4.1 General approach 58 5.4.2 Water level monitoring 60 5.4.3 Discharge monitoring 62 6 Discussion 66 6.1 Clarification of monitoring objectives and network structure 66 6.2 Improvement of cost-efficiency 67 6.3 General standards of national stations 68 6.4 Criteria on spatial estimation 68 6.5 Future prospects 70 x nwenveio 70 Acknowledgments 73 References 75 Appendix 1 79 Appendix 2 94 Appendix 3 95 Appendix 4 98 Appendix 5 100 Appendix 6 101 Appendix 7 103 Appendix 8 105 Structural development of the Finnish national hydrometric monitoring network 5 List of terms and abbreviations Basic station type Station classification according to the measured variable. The categories are (1) water level station, (2) discharge station, and (3) combined station. Basin A general term for a lake, a reservoir, or a river basin Catchment A synonym for river basin Cluster analysis Statistical network design method that was applied to the subnetwork of spatial estimation stations Combined station Station that measures both water level and discharge. Cost-efficiency index (of a network) In water level monitoring: the number of lake stations divided by the covered lake area. In discharge monitoring: the number of stations divided by the covered catchment area. Some specifications are given in 5.4.2 and 5.4.3. Discharge monitoring Covers the operation of discharge stations and combined stations Discharge station Station that measures only discharge Drainage basin A synonym for river basin EEA The European Environment Agency (coordinator of hydrometric monitoring at the European Union level) Evaluation of the original network Evaluation process, which included a classification of stations by monitoring objective, and individual estimation of stations Flow characteristic Some specified statistical parameter of discharge FNHS The Finnish National Hydrological Survey (the name used in this study for the coordinator of the national hydrometric network) GLS regression procedure The second of the three steps of NAUGLS Hydrometric monitoring In the present study: systematic observations of surface water level and river discharge. In international practice, two scopes are mostly being used: either the above (limited), or a wider defined e.g. by WIvIO and UNESCO (1992). 6 Puupponen Monographs of the Boreal Environment Research No. 12 Hydrometric monitoring system The entity of monitoring networks and modelling systems that produce data on surface water level and river discharge Independent catchment Independent catchments include (1) all main river basins, (2) all 1st division river subbasins, and (3) those river subbasins that represent the size categories <500 km2, 500—1,500 km2 1,500—3,000 km2, 3,000—6,000 km2 and> 6,000 km2 in any river system. Primarily, the catchments of points (1) and (2) represent the size categories. Secondarily, the representatives are the smallest 2nd division river subbasins in each gategory. Long-term monitoring Monitoring that has a minimum duration of 20 years. Generally, the duration is several decades. Main field of activity General classification of fields that are users of hydrometric data. The categories are (1) operational use and planning, (2) monitoring and research, and (3) protection of waters. Monitoring and research A main field of activity that includes four monitoring purposes: process study, enviromnental impact assessment, trend research, and water resources assessment and monitoring. Monitoring objective Station classification according to the type of information which is required. The categories are (1) water balance station, (2) spatial estimation station, (3) operational station, (4) planning and inventory station, and (5) research station. Monitoring practice Classification of practical solutions for the organisation of hydrometric measurements. The categories are: (1) long-term monitoring and (2) short-term observations. Monitoring purpose End-user’s specified need for hydrometric monitoring National hydrometric network The basic monitoring network of surface water level and river discharge (maintained by FNHS) NAUGLS (Network Analysis Using Generalised Least Squares) Statistical network design method that was applied to the subnetwork of spatial estimation stations NAUGLS ranking procedure The third of the three steps of NAUGLS Operational station Hydrometric station that has the main objective of measuring water level or discharge for the daily operation of various water resources projects Operational use and planning A main field of activity that includes five monitoring purposes: lake and river regulation, supervision of operation, flood management and dam safety, project planning and design, and planning of water supply.