Hydrologic Model Selection for the CFCAS Project: Assessment of Water Resources Risk and Vulnerability to Changing Climatic Conditions

The main purpose of this report is to present an up-to-date summary and comparison of existing hydrologic models that are potentially suitable for achieving the goals set in the Canadian Foundation for Climatic and Atmospheric Sciences (CFCAS) funded project “Assessment of Water Resources Risk and Vulnerability to Changing Climatic Conditions” (“project” hereafter). The report is intended to provide the information necessary for choosing the “right” model; a model which would be the most appropriate hydrologic modeling tool for the project in terms of various criteria. A two-level selection approach is used to objectively determine the most suitable model. At the first level a large number of existing hydrologic models are reviewed according to four fundamental selection criteria, and a subset of 18 models is identified. The selected 18 models are then ranked according to several evaluation criteria reflecting different aspects of specific project’s requirements. At the second level, total ranks attributed to the 18 selected models serve as an objective measure for determining the most appropriate model(s).https://ir.lib.uwo.ca/wrrr/1008/thumbnail.jp

Calibration, Verification and Sensitivity Analysis of the HEC-HMS Hydrologic Model

The main objective of this report is to describe the calibration, verification, and sensitivity analysis of the United States Army Corps of Engineers (USACE) Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) on the data from the Upper Thames River basin (UTRb) study area. The HEC-HMS model was chosen to be the most appropriate hydrologic modeling tool for achieving the goals set in the Canadian Foundation for Climatic and Atmospheric Sciences (CFCAS) funded project “Assessment of Water Resources Risk and Vulnerability to Changing Climatic Conditions” (“project” hereafter), (Cunderlik and Simonovic, 2003). The calibration, verification and sensitivity analysis of the HMS model are parts of the project Task 1: Development of a hydrologic model (ICLR, 2004).https://ir.lib.uwo.ca/wrrr/1010/thumbnail.jp

Selection of Calibration and Verification Data for the HEC-HMS Hydrologic Model

The main purpose of this report is to summarize the strategy applied for selecting the hydro-climatic data, which will be used for the calibration and verification of the US-ACE Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS). The HEC-HMS model was chosen to be the most appropriate hydrologic modeling tool for achieving the goals set in the Canadian Foundation for Climatic and Atmospheric Sciences (CFCAS) funded project “Assessment of Water Resources Risk and Vulnerability to Changing Climatic Conditions” (“project” hereafter), (Cunderlik, 2003).https://ir.lib.uwo.ca/wrrr/1009/thumbnail.jp

Production and Non-Production Functions of Grassland in an Upland Region of Slovakia

The importance of grassland lies chiefly in its production of good quality forage that is utilised by cattle and sheep. In upland and mountain regions the non-production functions of grassland such as landscape enhancement or water catchment are especially important. These functions are performed mainly through the sward tillering zone (boundary area between above-ground vegetation and roots) and root characteristics (Jancovic, l985). The objective of this research was to study the biomass above, at, and below ground level of three sward types at different fertilisation levels

Production and Non-Production Functions of Grassland in an Upland Region of Slovakia

The importance of grassland lies chiefly in its production of good quality forage that is utilised by cattle and sheep. In upland and mountain regions the non-production functions of grassland such as landscape enhancement or water catchment are especially important. These functions are performed mainly through the sward tillering zone (boundary area between above-ground vegetation and roots) and root characteristics (Jancovic, l985). The objective of this research was to study the biomass above, at, and below ground level of three sward types at different fertilisation levels

Statistical models for over-dispersion in the frequency of peaks over threshold data for a flow series.

In a peaks over threshold analysis of a series of river flows, a sufficiently high threshold is used to extract the peaks of independent flood events. This paper reviews existing, and proposes new, statistical models for both the annual counts of such events and the process of event peak times. The most common existing model for the process of event times is a homogeneous Poisson process. This model is motivated by asymptotic theory. However, empirical evidence suggests that it is not the most appropriate model, since it implies that the mean and variance of the annual counts are the same, whereas the counts appear to be overdispersed, i.e., have a larger variance than mean. This paper describes how the homogeneous Poisson process can be extended to incorporate time variation in the rate at which events occur and so help to account for overdispersion in annual counts through the use of regression and mixed models. The implications of these new models on the implied probability distribution of the annual maxima are also discussed. The models are illustrated using a historical flow series from the River Thames at Kingston

Regionalization by fuzzy expert system based approach optimized by genetic algorithm.

In recent years soft computing methods are being increasingly used to model complex hydrologic processes. These methods can simulate the real life processes without prior knowledge of the exact relationship between their components. The principal aim of this paper is perform hydrological regionalization based on soft computing concepts in the southern strip of the Caspian Sea basin, north of Iran. The basin with an area of 42,400 sq. km has been affected by severe floods in recent years that caused damages to human life and properties. Although some 61 hydrometric stations and 31 weather stations with 44 years of observed data (1961–2005) are operated in the study area, previous flood studies in this region have been hampered by insufficient and/or reliable observed rainfall-runoff records. In order to investigate the homogeneity (h) of catchments and overcome incompatibility that may occur on boundaries of cluster groups, a fuzzy expert system (FES) approach is used which incorporates physical and climatic characteristics, as well as flood seasonality and geographic location. Genetic algorithm (GA) was employed to adjust parameters of FES and optimize the system. In order to achieve the objective, a MATLAB programming code was developed which considers the heterogeneity criteria of less than 1 (H < 1) as the satisfying criteria. The adopted approach was found superior to the conventional hydrologic regionalization methods in the region because it employs greater number of homogeneity parameters and produces lower values of heterogeneity criteria

Flood seasonality across Scandinavia:Evidence of a shifting hydrograph?

Fluvial flood events have substantial impacts on humans, both socially and economically, as well as on ecosystems (e.g., hydroecology and pollutant transport). Concurrent with climate change, the seasonality of flooding in cold environments is expected to shift from a snowmelt-dominated to a rainfall-dominated flow regime. This would have profound impacts on water management strategies, that is, flood risk mitigation, drinking water supply, and hydro power. In addition, cold climate hydrological systems exhibit complex interactions with catchment properties and large-scale climate fluctuations making the manifestation of changes difficult to detect and predict. Understanding a possible change in flood seasonality and defining related key drivers therefore is essential to mitigate risk and to keep management strategies viable under a changing climate. This study explores changes in flood seasonality across near-natural catchments in Scandinavia using circular statistics and trend tests. Results indicate strong seasonality in flooding for snowmelt-dominated catchments with a single peak occurring in spring and early summer (March through June), whereas flood peaks are more equally distributed throughout the year for catchments located close to the Atlantic coast and in the south of the study area. Flood seasonality has changed over the past century seen as decreasing trends in summer maximum daily flows and increasing winter and spring maximum daily flows with 5–35% of the catchments showing significant changes at the 5% significance level. Seasonal mean daily flows corroborate those findings with higher percentages (5–60%) of the catchments showing statistically significant changes. Alterations in annual flood occurrence also point towards a shift in flow regime from snowmelt-dominated to rainfall-dominated with consistent changes towards earlier timing of the flood peak (significant for 25% of the catchments). Regionally consistent patterns suggest a first-order climate control as well as a local second-order catchment control, which causes inter-seasonal variability in the streamflow response

Land use change effects on extreme flood in the Kelantan basin using hydrological model

Land use and land cover (LULC) change results in increased of flood frequency and severity. The increase of annual runoff which is caused by urban development, heavy deforestation, or other anthropogenic activities occurs within the catchment areas. Therefore, accurate and continuous LULC change information is vital in quantifying flood hydrograph for any given time. Many studies showed the effect of land use change on flood based on hydrological response (i.e., peak discharge and runoff volume). In this study, a distributed hydrological modeling and GIS approach were applied for the assessment of land use impact in the Kelantan Basin. The assessment focuses on the runoff contributions from different land use classes and the potential impact of land use changes on runoff generation. The results showed that the direct runoff from developmental area, agricultural area, and grassland region is dominant for a flood event compared with runoff from other land-covered areas in the study area. The urban areas or lower planting density areas tend to increase for runoff and for the monsoon season floods, whereas the inter-flow from forested and secondary jungle areas contributes to the normal flow

On the variability of cold region flooding

Cold region hydrological systems exhibit complex interactions with both climate and the cryosphere. Improving knowledge on that complexity is essential to determine drivers of extreme events and to predict changes under altered climate conditions. This is particularly true for cold region flooding where independent shifts in both precipitation and temperature can have significant influence on high flows. This study explores changes in the magnitude and the timing of streamflow in 18 Swedish Sub-Arctic catchments over their full record periods available and a common period (1990-2013). The Mann-Kendall trend test was used to estimate changes in several hydrological signatures (e.g. annual maximum daily flow, mean summer flow, snowmelt onset). Further, trends in the flood frequency were determined by fitting an extreme value type I (Gumbel) distribution to test selected flood percentiles for stationarity using a generalized least squares regression approach.Results highlight shifts from snowmelt-dominated to rainfall-dominated flow regimes with all significant trends (at the 5% significance level) pointing toward (1) lower magnitudes in the spring flood; (2) earlier flood occurrence; (3) earlier snowmelt onset; and (4) decreasing mean summer flows. Decreasing trends in flood magnitude and mean summer flows suggest widespread permafrost thawing and are supported by increasing trends in annual minimum daily flows. Trends in selected flood percentiles showed an increase in extreme events over the full periods of record (significant for only four catchments), while trends were variable over the common period of data among the catchments. An uncertainty analysis emphasizes that the observed trends are highly sensitive to the period of record considered. As such, no clear overall regional hydrological response pattern could be determined suggesting that catchment response to regionally consistent changes in climatic drivers is strongly influenced by their physical characteristics