Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree. Calibration methods can involve formal optimization methods or manual methods in which the modeler informally examines alternative model parameters. The development of a calibration framework typically involves the following: (1) definition of the model variables, coefficients, and equations; (2) selection of an objective function to measure the quality of the calibration; (3) selection of the set of data to be used for the calibration process; and (4) selection of an optimization/manual scheme for altering the coefficient values in the direction of reducing the objective function. Hydraulic calibration usually involves the modification of system demands, fine-tuning the roughness values of pipes, altering pump operation characteristics, and adjusting other model attributes that affect simulation results, in particular those that have significant uncertainty associated with their values. From the previous steps, it is clear that model calibration is neither unique nor a straightforward technical task. The success of a calibration process depends on the modeler's experience and intuition, as well as on the mathematical model and procedures adopted for the calibration process. This paper provides a summary of the Battle of the Water Calibration Networks (BWCN), the goal of which was to objectively compare the solutions of different approaches to the calibration of water distribution systems through application to a real water distribution system. Fourteen teams from academia, water utilities, and private consultants participated. The BWCN outcomes were presented and assessed at the 12th Water Distribution Systems Analysis conference in Tucson, Arizona, in September 2010. This manuscript summarizes the BWCN exercise and suggests future research directions for the calibration of water distribution systems.
In the eastern temperate region of North America, treed headwater swamps are a familiar watershed feature. These low‐gradient wetlands commonly exist at groundwater discharge sites and represent a link between the underlying groundwater system and the surface drainage system. In contrast to the extensive literature pertaining to the hydrologic modeling of agricultural and forest land classes, little attention has been focused on the development and testing of numerical simulation models for predicting the hourly stormflow response from headwater wetland sites. If required to predict the rate of outflow from a wetland‐dominated catchment, the hydrologist or engineer has few numerical tools and little data available to assist in the prediction. The objective of this research was to investigate the feasibility of applying a numerical model to simulate the rainfall‐runoff response from a treed headwater wetland site. The wetland model utilizes a hydrology model coupled to a hydraulic stream‐routing model. A depth‐averaged laminar flow model is used to simulate the horizontal movement of stormwater both through and over the wetland sediments. The development and testing of the wetland model were completed in conjunction with a data collection program in which hydrometric and meteorologic data were obtained at a 400‐ha first‐order headwater swamp located within the Teeswater River watershed in southern Ontario, Canada. An analysis revealed that the simulated wetland streamflows were sensitive to the antecedent saturation of the wetland sediments, the storage and flow transport characteristics of the wetland sediments, and the conveyance capabilities of the wetland channel system.
In contrast to the extensive literature on hydrologic modeling of agricultural and urban land classes, relatively little attention has been focused on the prediction ofthe storm flow response from wetland ecosystems. If required to predictthe rate of outflow from a vvetland system, the hydrologist or engineer has few numerical tools and little available data to assist in the prediction. This chapter presents the application of a numerical wetland model using synthetic precipitation events. The wetland model consists of a field hydrology model fully coupled to a stream routing model. The field hydrology model incorporates two distinct layers, one representing the surficial hummock terrain common to many wetlands and the other representing the organic layer characteristic of all wetland sites. The hydrology model includes process representations for the quickflow responses associated with overland flows through the surficial hummock terrain and longterm subsurface interflow mechanisms within the wetland organics. Antecedent saturation states dictate the amount of storage available for temporarily storing meteorologic inputs. Under low saturation levels, the stormflow response is controHed by subsurface stonnflow mechanisms. Under high saturation levels, overland flow mechanisms shape the response. Over the past few years, the integration of adjacent urban la11d use has been a focus of discussion. The results of this study illustrate the complexity and variability of the hydrologic response at a wetland site, even to a single precipitation input. McKillop, R.C., N. Kouwen and E. Soulis. 1999 (Mitsch and Gosselink, 1986). Wetlands improve water quality, protect shorelines from erosion, provide a measure of flood control, and offer social and economic benefits. The importance of protecting and preserving these wetland systems is being increasingly recognized by the general public, water resources engineers and regulators. It is estimated that wetlands currently comprise 1,270,000 km 2 or 14% of Canada's land surface (National Wetlands Working Group, 1988). In Ontario, wetlands occupy approximately 33% of the land area or 290,000 km 2 , predominantly within the northern regions ofthe province. In southern Ontario, it has been estimated that over 75% of the wetland sites have been lost since European settlement (Ministries of Natural Resources and Municipal Affairs, 1992). In the past, the dominant cause of wetland loss in southern Ontario has been the reclamation of agricultural land use (Bardecki, 1981).At any wetland site, the hydrologic response is influenced by numerous factors. These include: the size and shape of the wetland, the microtopography of the wetland, the properties of the organic sediments, the interaction between the wetland and the channel network, the nature ofthe water inputs and amount of storage space available yvithin the organic sediments. It is recognized that the storm flow response of wetlands is strongly influenced by seasonal variations in both water inputs and evapotranspiration demand....
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