scholarly journals Regionalisation for lake level simulation – the case of Lake Tana in the Upper Blue Nile, Ethiopia

2011 ◽  
Vol 15 (4) ◽  
pp. 1167-1183 ◽  
Author(s):  
T. H. M. Rientjes ◽  
B. U. J. Perera ◽  
A. T. Haile ◽  
P. Reggiani ◽  
L. P. Muthuwatta
Keyword(s):  
Water Balance ◽  
Model Calibration ◽  
Lake Level ◽  
Regional Model ◽  
Model Parameters ◽  
Ungauged Catchments ◽  
Time Step ◽  
Lake Tana ◽  
Multi Objective ◽  
Objective Model

Abstract. In this study lake levels of Lake Tana are simulated at daily time step by solving the water balance for all inflow and outflow processes. Since nearly 62% of the Lake Tana basin area is ungauged a regionalisation procedure is applied to estimate lake inflows from ungauged catchments. The procedure combines automated multi-objective calibration of a simple conceptual model and multiple regression analyses to establish relations between model parameters and catchment characteristics. A relatively small number of studies are presented on Lake Tana's water balance. In most studies the water balance is solved at monthly time step and the water balance is simply closed by runoff contributions from ungauged catchments. Studies partly relied on simple ad-hoc procedures of area comparison to estimate runoff from ungauged catchments. In this study a regional model is developed that relies on principles of similarity of catchments characteristics. For runoff modelling the HBV-96 model is selected while multi-objective model calibration is by a Monte Carlo procedure. We aim to assess the closure term of Lake Tana's water balance, to assess model parameter uncertainty and to evaluate effectiveness of a multi-objective model calibration approach to make hydrological modeling results more plausible. For the gauged catchments, model performance is assessed by the Nash-Sutcliffe coefficient and Relative Volumetric Error and resulted in satisfactory to good performance for six, large catchments. The regional model is validated and indicated satisfactory to good performance in most cases. Results show that runoff from ungauged catchments is as large as 527 mm per year for the simulation period and amounts to approximately 30% of Lake Tana stream inflow. Results of daily lake level simulation over the simulation period 1994–2003 show a water balance closure term of 85 mm per year that accounts to 2.7% of the total lake inflow. Lake level simulations are assessed by Nash Sutcliffe (0.91) and Relative Volume Error (2.71%) performance measures.

scholarly journals Multi-objective regionalisation for lake level simulation, the case of Lake Tana in the Upper Blue Nile, Ethiopia

2010 ◽  
Vol 7 (5) ◽  
pp. 7341-7381
Author(s):  
T. H. M. Rientjes ◽  
B. U. J. Perera ◽  
A. T. Haile ◽  
P. Reggiani
Keyword(s):  
Water Balance ◽  
Lake Level ◽  
Ad Hoc ◽  
Relative Volume ◽  
Model Parameters ◽  
Lake Levels ◽  
Ungauged Catchments ◽  
Time Step ◽  
Lake Tana ◽  
Multi Objective

Abstract. The aim in this study is to simulate lake levels of Lake Tana by solving the water balance at daily time step. Since 42% of the basin is ungauged regionalisation procedures are applied. We examine the predictive capability of a regionalisation approach that combines multi-objective calibration of a simple conceptual model and multi regression analyses to establish relations between model parameters and catchment characteristics. Recently few studies are presented on lake level simulation of Lake Tana. In these studies the water balance of the lake is closed by estimation of runoff contributions from ungauged catchments. Studies partly relied on simple ad-hoc procedures of area comparison to estimate runoff from ungauged catchments. In this study a regional model is developed that relies on principles of similarity of catchments. For runoff modelling the HVB-96 model is selected while multi-objective model calibration is by a Monte Carlo procedure. Assessment of the lake water balance was established by comparing measured to estimated lake levels. Results of daily lake level simulation show a water balance closure term of 85 mm and a relative volume error of 2.17%. Results show runoff from ungauged catchments of 527 mm per year for the simulation period 1994 to 2003 that is approximately 30% of Lake Tana stream flow inflow. Compared to previous works this closure term is smallest.

A Novel Multi-Objective Model Calibration Method for Ecohydrological Applications

2021 ◽  
pp. 105161
Author(s):  
J. Sebastian Hernandez-Suarez ◽  
A. Pouyan Nejadhashemi ◽  
Kalyanmoy Deb
Keyword(s):  
Model Calibration ◽  
Calibration Method ◽  
Multi Objective ◽  
Objective Model

scholarly journals Estimation of parameters in a distributed precipitation-runoff model for Norway

2003 ◽  
Vol 7 (3) ◽  
pp. 304-316 ◽  
Author(s):  
S. Beldring ◽  
K. Engeland ◽  
L. A. Roald ◽  
N. R. Sælthun ◽  
A. Voksø
Keyword(s):  
Land Surface ◽  
Distributed Model ◽  
Small Scale ◽  
Model Parameters ◽  
Estimation Of Parameters ◽  
Ungauged Catchments ◽  
Time Step ◽  
Landscape Characteristics ◽  
Average Annual Runoff ◽  
Scale Properties

Abstract. A distributed version of the HBV-model using 1 km2 grid cells and daily time step was used to simulate runoff from the entire land surface of Norway for the period 1961-1990. The model was sensitive to changes in small scale properties of the land surface and the climatic input data, through explicit representation of differences between model elements, and by implicit consideration of sub-grid variations in moisture status. A geographically transferable set of model parameters was determined by a multi-criteria calibration strategy, which simultaneously minimised the residuals between model simulated and observed runoff from 141 Norwegian catchments located in areas with different runoff regimes and landscape characteristics. Model discretisation units with identical landscape classification were assigned similar parameter values. Model performance was evaluated by simulating discharge from 43 independent catchments. Finally, a river routing procedure using a kinematic wave approximation to open channel flow was introduced in the model, and discharges from three additional catchments were calculated and compared with observations. The model was used to produce a map of average annual runoff for Norway for the period 1961-1990. Keywords: distributed model, multi-criteria calibration, global parameters, ungauged catchments.

scholarly journals Modelling catchment inflows into Lake Victoria: regionalisation of the parameters of a conceptual water balance model

2012 ◽  
Vol 44 (5) ◽  
pp. 789-808 ◽  
Author(s):  
Michael Kizza ◽  
Jose-Luis Guerrero ◽  
Allan Rodhe ◽  
Chong-yu Xu ◽  
Henry K. Ntale
Keyword(s):  
Water Balance ◽  
Model Calibration ◽  
Lake Victoria ◽  
Uncertainty Assessment ◽  
Uncertainty Estimation ◽  
Water Balance Model ◽  
Balance Model ◽  
Model Parameters ◽  
Lake Victoria Basin ◽  
Global Mean

The goal of this study was to evaluate regionalisation methods that could be used for modelling catchment inflows into Lake Victoria. WASMOD, a conceptual water balance model, was applied to nine gauged sub-basins in Lake Victoria basin in order to test the transferability of model parameters between the basins using three regionalisation approaches. Model calibration was carried out within the GLUE (generalised likelihood uncertainty estimation) framework for uncertainty assessment. The analysis was carried out for the period 1967–2000. Parameter transferability was assessed by comparing the likelihood values of regionalised simulations with the values under calibration for each basin. WASMOD performed well for all study sub-basins with Nash–Sutcliffe values ranging between 0.70 and 0.82. Transferability results were mixed. For the proxy-basin method, the best performing parameter donor basin was Mara with four proxy basins giving acceptable results. Sio, Sondu, Gucha and Duma also performed well. The global mean method gave acceptable performance for seven of the nine study basins. The ensemble regionalisation method provides the possibility to consider parameter uncertainty in the regionalisation. Ensemble regionalisation method performed best with an average departure of 40% from the observed mean annual flows compared to 48 and 60% for proxy-basin and global mean methods, respectively.

scholarly journals Catchment modeling and model transferability in upper Blue Nile Basin, Lake Tana, Ethiopia

2008 ◽  
Vol 5 (2) ◽  
pp. 811-842 ◽  
Author(s):  
A. S. Gragne ◽  
S. Uhlenbrook ◽  
Y. Mohammed ◽  
S. Kebede
Keyword(s):  
Water Resources ◽  
Water Resource Management ◽  
Model Parameters ◽  
Hydrological Process ◽  
Runoff Generation ◽  
Time Step ◽  
Lake Tana ◽  
Blue Nile ◽  
Model Transferability ◽  
Catchment Modeling

Abstract. Understanding spatial and temporal distribution of water resources has an important role for water resource management. To understand water balance dynamics and runoff generation mechanisms at the Gilgel Abay catchment (a major tributary into lake Tana, source of Blue Nile, Ethiopia) and to evaluate model transferability, catchment modeling was conducted using the conceptual hydrological model HBV. The catchment of the Gigel Abay was sub-divided into two gauged sub-catchments (Upper Gilgel Abay, UGASC, and Koga, KSC) and one ungauged sub-catchment. Manual calibration of the daily models for three different catchment representations (CRs): (i) lumped, (ii) lumped with multiple vegetation zones, and (iii) semi-distributed with vegetations zone and elevation zones, showed good to satisfactory model performance (Nash-Sutcliffe efficiency values, Reff>0.75 and >0.6, respectively, for UGASC and KSC). The change of the time step to fifteen and thirty days resulted in very good model performances in both sub-catchments (Reff>0.8). The model parameter transferability tests conducted on the daily models showed poor performance in both sub-catchments, whereas the fifteen and thirty days models yielded high Reff values using transferred parameter sets. This together with the sensitivity analysis carried out after Monte Carlo simulations (1 000 000 model runs) per CR explained the reason behind the difference in hydrologic behaviors of the two sub-catchments UGASC and KSC. The dissimilarity in response pattern of the sub-catchments was caused by the presence of dambos in KSC and differences in the topography between UGASC and KSC. Hence, transferring model parameters from the view of describing hydrological process was found to be not feasible for all models. On the other hand, from a water resources management perspective the results obtained by transferring parameters of the larger time step model were acceptable.

Estimation of flow in ungauged catchments by coupling a hydrological model and neural networks: case study

2011 ◽  
Vol 42 (5) ◽  
pp. 386-400 ◽  
Author(s):  
A. H. Saliha ◽  
S. B. Awulachew ◽  
J. Cullmann ◽  
Hans-B. Horlacher
Keyword(s):  
Regional Model ◽  
Homogeneous Group ◽  
Low Flow ◽  
Model Parameters ◽  
Watershed Model ◽  
Ungauged Catchments ◽  
Kohonen Neural Network ◽  
Catchment Characteristics ◽  
Ungauged Basin ◽  
Distributed Hydrological Models

The prediction of hydrological variables for ungauged basins is still a big challenge. Regionalization is the most widely used method to date, which relates parameters of watershed models to catchment characteristics. Relating catchment characteristics to watershed model parameters is too difficult for distributed hydrological models, due to the heterogeneous nature of catchments. A regional model was proposed by coupling a Kohonen neural network (KNN) and distributed Water Balance Simulation Model (WaSiM-ETH) to estimate flow in ungauged basin. KNN was used to delineate a hydrological homogeneous group based on predefined physical characteristics of catchments and WaSiM-ETH was applied to generate daily stream flow. Twenty-six subcatchments of the Blue Nile River basin, Ethiopia, were grouped into five hydrological homogenous groups, each with its own full set of optimized WaSiM-ETH parameters. In the regional model, the KNN assigned the ungauged catchment into one of the five hydrological homogenous groups. The whole set of optimized WaSiM parameters from the homogeneous group (which the ungauged river belongs to) were transferred to the ungauged river and WaSiM-ETH was used to compute the flow for this ungauged river. The regional model generally overestimated the low flow. In general, the results for validation subcatchments showed the regional model is satisfactory in transferring information from data-rich to data-poor catchments.

scholarly journals Quantifying the Regional Water Balance of the Ethiopian Rift Valley Lake Basin Using an Uncertainty Estimation Framework

2021 ◽  
Author(s):  
Tesfalem Abraham ◽  
Yan Liu ◽  
Sirak Tekleab ◽  
Andreas Hartmann
Keyword(s):  
Water Balance ◽  
Rift Valley ◽  
Model Parameters ◽  
Lake Basin ◽  
Climatic Data ◽  
Ungauged Catchments ◽  
Regional Regression ◽  
Validation Parameters ◽  
Global Precipitation ◽  
Regional Water

Abstract. In Ethiopia more than 80 % of big freshwater lakes are located in the Rift Valley Lake Basin (RVLB), serving over 15 million people a multipurpose water supply. The basin covers an area of 53,035 km2, and most of the catchments recharging these lakes are ungauged and their water balance is not well quantified, hence limiting the development of appropriate water resource management strategies. Prediction for ungauged basins (PUB) has demonstrated its effectiveness in hydro-climatic data-rich regions. However, these approaches are not well evaluated in climatic data-limited conditions and the consequent uncertainty is not adequately quantified. In this study we use the Hydrologiska Byråns Vattenbalansavdelning (HBV) model to simulate streamflow at a regional scale using global precipitation and potential evapotranspiration products as forcings. We develop and apply a Monte-Carlo scheme to estimate model parameters and quantify uncertainty at 16 catchments in the basin where gauging stations are available. Out of these 16, we use the 14 most reliable catchments to derive the best regional regression model. We use three different strategies to extract possible parameter sets for regionalization by correlating the best calibration parameters, the best validation parameters, and parameters that give the most stable predictions with catchment properties that are available throughout the basin. A weighting scheme in the regional regression accounts for parameter uncertainty in the calibration. A spatial cross-validation is applied multiple times to test the quality of the regionalization and to estimate the regionalization uncertainty. Our results show that, other than the commonly used best-calibrated parameters, the best parameter sets of the validation period provide the most robust estimates of regionalized parameters. We then apply the regionalized parameter sets to the remaining 35 ungauged catchments in the RVLB to provide regional water balance estimations, including quantifications of regionalization uncertainty. The uncertainties of elasticities from the regionalization in the ungauged catchments are higher than those obtained from the simulations in the gauged catchments. With these results, our study provides a new procedure to use global precipitation and evapotranspiration products to predict and evaluate streamflow simulation for hydro-climatically data-scarce regions considering uncertainty. This procedure enhances the confidence to understand the water balance of under-represented regions like ours and supports the planning and development of water resources.

scholarly journals A conceptual model of daily water balance following partial clearing from forest to pasture

2006 ◽  
Vol 10 (3) ◽  
pp. 321-337 ◽  
Author(s):  
M. A. Bari ◽  
K. R. J. Smettem
Keyword(s):  
Soil Moisture ◽  
Water Balance ◽  
Soil Depth ◽  
Groundwater Depth ◽  
Balance Model ◽  
Model Parameters ◽  
Stream Length ◽  
Time Step ◽  
Moisture Balance ◽  
Soil Moisture Balance

Abstract. A simple conceptual water balance model representing the streamflow generation processes on a daily time step following land use change is presented. The model consists of five stores: (i) Dry, Wet and Subsurface Stores for vertical and lateral water flow, (ii) a transient Stream zone Store (iii) a saturated Goundwater Store. The soil moisture balance in the top soil Dry and Wet Stores are the most important components of the model and characterize the dynamically varying saturated areas responsible for surface runoff, interflow and deep percolation. The Subsurface Store describes the unsaturated soil moisture balance, extraction of percolated water by vegetation and groundwater recharge. The Groundwater Store controls the baseflow to stream (if any) and the groundwater contribution to the stream zone saturated areas. The daily model was developed following a downward approach by analysing data from Ernies (control) and Lemon (53% cleared) catchments in Western Australia and elaborating a monthly model. The daily model performed very well in simulating daily flow generation processes for both catchments. Most of the model parameters were incorporated a priori from catchment attributes such as surface slope, soil depth, porosity, stream length and initial groundwater depth, and some were calibrated by matching the observed and predicted hydrographs. The predicted groundwater depth, and streamflow volumes across all time steps from daily to monthly to annual were in close agreement with observations for both catchments.

scholarly journals Water balance modeling of Upper Blue Nile catchments using a top-down approach

2010 ◽  
Vol 7 (5) ◽  
pp. 6851-6886 ◽  
Author(s):  
S. Tekleab ◽  
S. Uhlenbrook ◽  
Y. Mohamed ◽  
H. H. G. Savenije ◽  
S. Ayalew ◽  
...  
Keyword(s):  
Water Balance ◽  
Model Complexity ◽  
Model Parameters ◽  
Nile Basin ◽  
Top Down ◽  
Ungauged Catchments ◽  
Blue Nile ◽  
Blue Nile Basin ◽  
High Flows ◽  
Upper Blue Nile Basin

Abstract. The hydrological behavior and functioning of twenty catchments in the Upper Blue Nile basin have been analyzed using a top-down modeling approach that is based on Budyko's hypotheses. The objective is to obtain better understanding of catchment response for prediction in ungauged catchments. The water balance analysis using Budyko-type curve at annual scale reveals that the aridity index does not exert a first order control in most of the catchments. This implies the need to increase model complexity to a monthly time scale to include the effects of seasonal soil moisture dynamics. The dynamic water balance model used in this study predicts the direct runoff and other processes based on limit concept. The uncertainty of model parameters has been assessed using the GLUE (Generalized Likelihood Uncertainty Estimation). The results show that the majority of the parameters are reasonably well identifiable. Moreover, a multi-objective model calibration strategy has been employed within the GLUE framework to emphasize the different aspects of the hydrographs on low and high flows. The model has been calibrated and validated against observed streamflow time series and it shows good performance for the twenty catchments of the upper Blue Nile. During the calibration period (1995–2000) the Nash and Sutcliffe coefficient of efficiency for monthly flow prediction varied between 0.52 to 0.93 during high flows, while it varied between 0.32 to 0.90 during low flows (logarithms of flow series). The model is parsimonious and it is suggested that the resulting parameters can be used to predict monthly stream flows in the ungauged catchments of the Upper Blue Nile basin, which accounts about 60% of total Nile basin flow.

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