Water Management Advantages of Comprehensive Representation of Wetlands in anIntegrated HSPF-Modflow Hydrologic Model

摘要

Open water and wetlands, referred to as wetlands, comprise 25% of the westcentralFlorida landscape and locally, can cover a much larger proportion of thelandscape. Local and regional water budgets and the spatial and temporal distributionof evapotranspiration, streamflow, baseflow, and recharge to the water table areinfluenced by the spatial extent and type of wetlands. Management of water resourcesfor annual and seasonal scales is significantly influenced by the presence of wetlands.Tampa BayWater is a wholesale water utility that delivers almost 170 million gallonsper day average annual (2005) of drinking water from a diverse set of sourcesincluding ground water and surface water. Tampa BayWater has found that wetlandsplay a key role when optimizing the withdrawal of water from these sources and thatoptimization must account for inter-seasonal and inter-annual response of thecombined surface and ground-water hydrologic system which is a function ofhydrologic storage. In this context, simulation of the combined surface and groundwatersystem for water management purposes requires a more comprehensiverepresentation of wetlands than has been used in past modeling activities. Throughmanagement of the diverse drinking water sources using various tools includingintegrated surface and ground-water hydrologic models, Tampa BayWater concludedthat water management could be improved using a more comprehensive and spatiallyexplicitsimulation of wetland hydrology within the integrated model framework.Comprehensive representation includes all wetland features from a land use mapusing a spatially distributed format, explicit and unique hydrologic simulation unitsfor land and wetlands, unique simulation of different wetland types includingdifferences in storage characteristics, transition in evapotranspiration from waterabove land to water below land in wetlands, and dynamic hydraulic connectionbetween ground water and wetlands. In response to the need for more comprehensivesimulation of wetland systems and other processes, a model called IntegratedHydrologic Model (IHM) has evolved from a prior HSPF-Modflow integrated model.Using the IHM and the principles on which it was developed, the Integrated NorthernTampa Bay (INTB) model has been developed and calibrated over a 10,400 square km (4,000 square mile) region. It is anticipated that the INTB model will be used asone of many emerging tools with which to improve management of water resourcesin west-central Florida.