Identification of spatially distributed precipitation-runoff response routines for hourly simulation in gauged and ungauged basins
Doctoral thesis
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http://hdl.handle.net/11250/283321Utgivelsesdato
2015Metadata
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Sammendrag
Due to sudden and considerable flow fluctuations during hydropeaking operation,
forecasting of inflow to hydropower reservoirs at high temporal resolution (e.g. hourly)
is required. Prediction of streamflow for both gauged and ungauged basins using
Precipitation-Runoff (P-R) models is widely employed for operational purposes.
However, there are various challenging factors and inherent uncertainties in the P-R
modelling. Moreover, for the boreal Norwegian catchments there are research gaps for
prediction of hourly streamflow related to identification of suitable parameterizations,
model structures and regionalization methods for prediction in ungauged basins (PUB).
Therefore, to address some of the research gaps, comprehensive calibration and postcalibration
comparative evaluation of the performances of the different runoff response
routines for both catchment and regional scale modelling are required. This is required
to improve the runoff simulation based on observed input climate forcing (simulation
mode) and hence for the improvement of hydrological forecast (forecast mode).
The objective of the first paper (P1) in this study was the identification of six
different cases of explicitly resolved or probabilistic parameterizations of the spatial
heterogeneity of a single state subsurface storage capacity. We conducted semidistributed
and distributed simulations based on the ‘fill-and-spill’ saturation excess,
infiltration excess and subsurface drainage runoff mechanisms. Equivalent
performances of simulation from the different cases indicate the unidentifiably of the
parameterizations and hence a preference for a parsimonious simple distributed
parameterization. Identification requires more representative input climate data than a
mere calibration problem. In addition, calibration only to streamflow data cannot fully
identify the parameterizations.
In light of the findings from the first paper, we conducted a study on identification of
parametrical parsimonious and more complex configurations of the widely used
conceptual Hydrologiska Byråns Vattenbalansavdelning (HBV) runoff response routine
in the second paper (P2). Despite equivalent streamflow simulations for the tested HBV
variants, a parametrical parsimonious HBV routine (HBV-Parsim) provided better
parameter identifiability and more reliable baseflow simulation. In the other variants,
considerable interactions between the soil moisture accounting and the response routine parameters and compensation between the outflow from the upper reservoir and the
baseflow from the lower reservoir affect the reliability of the simulation. Hence,
evaluation of the reliability of internal simulations of baseflow and soil moisture by the
widely used HBV routines against tailor-made analytical methods or observations is
necessary.
Inspired by the preference to parsimony in P1 and P2 and the compensation between
the fluxes from multiple storage reservoirs of the conceptual model in P2, our objective
in P3 was geared towards the evaluation of the performance of a distributed version of a
‘top-down’ parsimonious single storage routine (hereafter named Kirchmod). We
applied the principle of catchments as simple dynamical systems following Kirchner
(2009) for a macroscale (3090 km2) mountainous catchment of considerable runoff
delay compared to the hourly simulation. In this case, we both set the response routine
parameters by estimation from streamflow recession analysis and by calibration. We
obtained simulated streamflow hydrographs and flow duration curves that are in good
agreement with the observed and transferability of the optimal parameter sets to the
interior subcatchments validated the model. However, the parameter calibration
provides slightly better simulation of peak flows than estimation from the recession
analysis. In addition, the various sources of uncertainty in parameter estimation needs
thorough assessment. There is no marked influence of the runoff delay due to the
correlation among the free parameters, which indicates problems of parameter nonidentifiability
even for the parsimonious routine.
Based on the findings from the catchment scale performances of the P-R response
routines in P1, P2 and P3, we wished to address the issues of Prediction in Ungauged
Basins (PUB) through multi-model identification of different regionalization methods
on 26 catchments in a mid-Norway study region in P4. We found that the best
performing regionalization methods for the catchments vary among the model structures
and evaluation metrics. However, based on the regional performances, the
regionalization methods based on the single-donor physical similarity and the multidonor
regional calibration corresponding to maximum regional weighted average
(MRWA) performance measures (PM) performed better than the nearest neighbor and
regional median parameters. The lack of data on the subsurface physical attributes and high- density hourly hydro-climatic gauging networks for the region can affect the
performances of the regionalization methods, which needs scrutiny in future endeavors.
The fifth objective was the identification of distributed P-R response routines relevant
to operational purposes based on a multi-basin (26 catchments) local and regional
calibration in P5. The best performing model structure(s) vary among the catchments
and the evaluation metrics and hence there is no unique model structure that performs
best for all catchments in the region. However, the Kirchmod followed by the BGM
perform better than the various configurations of the HBV routine for the majority of
the catchments and in terms of the regional calibration (MRWA) for the PUB.
Therefore, flexible models and a multi-basin modelling framework, which allow
identification of models for hourly simulation among a pool of plausible options for
several catchments in the region, is better than the common single catchment model for
operational purposes.
In P1 to P5, we observed the challenges in identifying a unique regional P-R response
routine due to the uniqueness of catchments runoff response and various sources of
uncertainties. The last objective of the thesis was the development of data based
statistical model and comparative evaluations against the best performing P-R response
routine for hourly prediction in an ungauged and regulated basin for ecological
applications in P6. A simple regional regression model based on the relationship among
streamflow percentiles and catchment drainage areas, and regional transfer of
streamflow information to the nearest neighbor catchment performed better than the
MRWA based transfer of model parameters using the Kirchmod. We found the simple
regional regression model to be useful to predict a natural time series of streamflow in a
regulated river to derive ecologically relevant streamflow metrics, for assessing
hydrological alterations due to regulation and hydropeaking and environmental flows.
Består av
Paper 1: Hailegeorgis, Teklu Tesfaye; Alfredsen, Knut; Abdella, Yisak Sultan; Kolberg, Sjur. Evaluation of different parameterizations of the spatial heterogeneity of subsurface storage capacity for hourly runoff simulation in boreal mountainous watershed. Journal of Hydrology 2015 ;Volum 522. s. 522-533 http://dx.doi.org/10.1016/j.jhydrol.2014.12.061Paper 2: Hailegeorgis, Teklu Tesfaye; Alfredsen, Knut. Comparative evaluation of performances of different conceptualisations of distributed HBV runoff response routines for prediction of hourly streamflow in boreal mountainous catchments. Hydrology Research 2015 s. is not included due to copyright . available at http://www.iwaponline.com/nh/up/nh2014051.htm
Paper 3: Teklu T. Hailegeorgis, Knut Alfredsen, Yisak S. Abdella and Sjur Kolberg. Distributed hourly runoff computations in mountainous boreal catchments from This is an Author's Original Manuscript of an Article submitted to the Hydrological Sciences Journal available online at http://www.tandfonline.com/ ‘catchments as simple dynamical systems’ storage-discharge relationships
Paper 4: Hailegeorgis, Teklu Tesfaye; Abdella, Yisak Sultan; Alfredsen, Knut; Kolberg, Sjur. Evaluation of Regionalization Methods for Hourly Continuous Streamflow Simulation Using Distributed Models in Boreal Catchments. Journal of hydrologic engineering 2015 http://dx.doi.org/10.1061/(ASCE)HE.1943-5584.0001218
Paper 5: Teklu T. Hailegeorgis and Knut Alfredsen. Multi-basin and regional calibration based identification of distributed Precipitation- Runoff models for prediction of hourly streamflow on 26 catchments in mid-Norway
Paper 6: Teklu T. Hailegeorgis and Knut Alfredsen. Regional statistical and Precipitation-Runoff modelling for ecological applications: prediction of hourly streamflow in regulated Rivers and ungauged basins - is not included due to copyright