5 resultados para Irrigation and drainage
em Digital Commons at Florida International University
Resumo:
The management and restoration of the Biscayne Bay Coastal Wetlands (BBCW) is a complex issue. Unlike other natural areas under the supervision of the National Park System, the BBCW had endured many years of neglect and abuse by homesteaders who, prior to the establishment of Biscayne National Monument in 1968, had free reign of the area and tried to farm and develop the land by ditching and infilling. Furthermore, public works projects, dating back to the early 1900’s for mosquito control, land reclamation, and storm surge protection along with homesteader activities have combined to compartmentalize the coastal wetlands of present Biscayne National Park and adjacent marshes.
Resumo:
Pesticide monitoring in St. Lucie County by various local, state and federal agencies has indicated consistent residues of several pesticides, including ethion and bromacil. Although pesticides have long been known to pose a threat to non-target species and much background monitoring has been done, no pesticide aquatic risk assessment has been done in this geographical area. Several recognized United States Environmental Protection Agency (USEPA) methods of quantifying risk are employed here to include hazard quotients (HQ) and probabilistic modeling with sensitivity analysis. These methods are employed to characterize potential impacts to aquatic biota of the C-25 Canal and the Indian River Lagoon (in St. Lucie County, Florida) based on current agricultural pesticide use and drainage patterns. The model used in the analysis incorporates available physical-chemical property data, local hydrology, ecosystem information, and pesticide use practices. HQ's, probabilistic distributions, and field sample analyses resulted in high levels of concern (LOCs), which usually indicates a need for regulatory action, including restrictions on use, or cancellation. ^
Resumo:
The Mara River Basin (MRB) is endowed with pristine biodiversity, socio-cultural heritage and natural resources. The purpose of my study is to develop and apply an integrated water resource allocation framework for the MRB based on the hydrological processes, water demand and economic factors. The basin was partitioned into twelve sub-basins and the rainfall runoff processes was modeled using the Soil and Water Assessment Tool (SWAT) after satisfactory Nash-Sutcliff efficiency of 0.68 for calibration and 0.43 for validation at Mara Mines station. The impact and uncertainty of climate change on the hydrology of the MRB was assessed using SWAT and three scenarios of statistically downscaled outputs from twenty Global Circulation Models. Results predicted the wet season getting more wet and the dry season getting drier, with a general increasing trend of annual rainfall through 2050. Three blocks of water demand (environmental, normal and flood) were estimated from consumptive water use by human, wildlife, livestock, tourism, irrigation and industry. Water demand projections suggest human consumption is expected to surpass irrigation as the highest water demand sector by 2030. Monthly volume of water was estimated in three blocks of current minimum reliability, reserve (>95%), normal (80–95%) and flood (40%) for more than 5 months in a year. The assessment of water price and marginal productivity showed that current water use hardly responds to a change in price or productivity of water. Finally, a water allocation model was developed and applied to investigate the optimum monthly allocation among sectors and sub-basins by maximizing the use value and hydrological reliability of water. Model results demonstrated that the status on reserve and normal volumes can be improved to ‘low’ or ‘moderate’ by updating the existing reliability to meet prevailing demand. Flow volumes and rates for four scenarios of reliability were presented. Results showed that the water allocation framework can be used as comprehensive tool in the management of MRB, and possibly be extended similar watersheds.
Resumo:
Many coastal wetland communities of south Florida have been cut off from freshwater sheet flow for decades and are migrating landward due to salt-water encroachment. A paleoecological study using mollusks was conducted to assess the rates and effects of salt-water encroachment due to freshwater diversion and sea level rise on coastal wetland basins in Biscayne National Park. Modem mollusk distributions taken from 226 surface sites were used to determine local habitat affinities which were applied to infer past environments from mollusk distributions found in soil cores. Mollusks species compositions were found to be strongly correlated to habitat and salinity, providing reliable predictions. Wetland soils were cored to bedrock at 36locations. Mollusks were abundant throughout the cores and 15 of the 20 most abundant taxa served as bioindicators of salinity and habitat. Historic accounts coupled with mollusk based inference models indicate (1) increasing salinity levels along the coast and encroaching into the interior with mangroves communities currently migrating westward, (2) replacement of a mixed graminoid-mangrove zone by a dense monoculture of dwarf mangroves, and (3) a confinement of freshwater and freshwater graminoid marsh to landward areas between urban developments and drainage canals.
Resumo:
Non-native fishes present a management challenge to maintaining Everglades National Park (ENP) in a natural state. We summarized data from long-term fish monitoring studies in ENP and reviewed the timing of introductions relative to water-management changes. Beginning in the early 1950s, management actions have added canals, altered wetland habitats by flooding and drainage, and changed inflows into ENP, particularly in the Taylor Slough/C-111 basin and Rocky Glades. The first non-native fishes likely entered ENP by the late 1960s, but species numbers increased sharply in the early 1980s when new water-management actions were implemented. After 1999, eight non-native species and three native species, all previously recorded outside of Park boundaries, were found for the first time in ENP. Several of these incursions occurred following structural and operational changes that redirected water deliveries to wetlands open to the eastern boundary canals. Once established, control non-native fishes in Everglades wetlands is difficult; therefore, preventing introductions is key to their management. Integrating actions that minimize the spread of non-native species into protected natural areas into the adaptive management process for planning, development, and operation of water-management features may help to achieve the full suite of objectives for Everglades restoration.