Minimum Flows and Levels Method of the St. Johns River Water Management District, Florida, USA

Abstract

The St. Johns River Water Management District (SJRWMD) has developed a minimum flows and levels (MFLs) method that has been applied to rivers, lakes, wetlands, and springs. The method is primarily focused on ecological protection to ensure systems meet or exceed minimum eco-hydrologic requirements. MFLs are not calculated from past hydrology. Information from elevation transects is typically used to determine MFLs. Multiple MFLs define a minimum hydrologic regime to ensure that high, intermediate, and low hydrologic conditions are protected. MFLs are often expressed as statistics of long-term hydrology incorporating magnitude (flow and/ or level), duration (days), and return interval (years). Timing and rates of change, the two other critical hydrologic components, should be sufficiently natural. The method is an event-based, non-equilibrium approach. The method is used in a regulatory water management framework to ensure that surface and groundwater withdrawals do not cause significant harm to the water resources and ecology of the above referenced system types. MFLs are implemented with hydrologic water budget models that simulate long-term system hydrology. The method enables a priori hydrologic assessments that include the cumulative effects of water withdrawals. Additionally, the method can be used to evaluate management options for systems that may be over-allocated or for eco-hydrologic restoration projects. The method can be used outside of the SJRWMD. However, the goals, criteria, and indicators of protection used to establish MFLs are system-dependent. Development of regionally important criteria and indicators of protection may be required prior to use elsewhere.

Hindcasting multidecadal predevelopment groundwater levels in the Floridan aquifer

“…Long‐term data is vital for resolving a range of water‐resource issues including groundwater availability, land subsidence, changes in groundwater quality, setting minimum levels, and surface water and groundwater interaction (Alley et al 1999; Taylor and Alley 2001; Neubauer et al 2008; Jackson et al 2016). Although essential for characterizing the impacts of climate change and withdrawals, groundwater level data extending 50 years or more are rare (Taylor and Alley 2001; Stoll et al 2011; Jackson et al 2015; Jackson et al 2016).…”

Aspectos conceituais sobre o regime hidrológico para a definição do hidrograma ambiental

“…Jain e Srinivasulu (2006) apresentam divisões para o hidrograma mais discretizadas com ascendência em duas partes (segmento inicial e outro próximo ao cume sob maior influência do fluxo superficial, destacando-se que os processos físicos ocorrentes no primeiro são bastante diferenciados do segundo) e o ramo cadente em três partes (parte inicial nas proximidades do pico, parte mediana, influenciado pelo escoamento sub-superficial, e o segmento final -escoamento de base). A Figura 3 resume a separação do hidrograma adaptado de Shaw (2005) Poff et al (1997) citam que a variabilidade hidrológica é influenciada pela magnitude, duração, frequência e época de ocorrência de vazões mínimas e máximas (Jacobson e Galat, 2006;Neubauer et al, 2008;Masih et al, 2009;Gao et al, 2009;Wen, 2009;Zeilhofera e Moura, 2009), ilustrativamente observadas em Bunn e Arthington (2002) (Tucci 2009, Naiman et al, 2008, em que se destacam quatro princípios sobre a influência do regime natural de vazões na biodiversidade ripária mediante vários mecanismos relacionados no tempo e no espaço, resumidamente expressos em um hidrograma, atentando-se: às relações entre a diversidade ecológica e fluxo do canal (mudanças geomorfológicas pelas grandes vazões); a variabilidade hidrológica (sazonalidade); as trocas de fluxo vertical e lateral no escoamento (ressalta-se, mais uma vez, as supracitadas fases de rio efluente e influente) e as alterações no regime natural do fluxo quanto as espécies invasivas.…”

Evaluation of Sustainable Environmental Flows Based on the Valuation of Ecosystem Services: a Case Study for the Baiyangdian Wetland, China

“…We used canonical correlation analysis and gray relationship analysis to re-veal the relationships between the wetland's ecosystem services value and hydrological data, and used a nonlinear curve-fitting approach to evaluate the sustainable ranges of values for key hydrological parameters, thereby revealing the range of sustainable environmental flows that is possible under the existing constraints. This research provides more useful results than those provided by an approach based on supplying the minimum environmental flows (Zhao et al, 2005;Neubauer et al, 2008;Zhong et al, 2008) because it accounts for ecologically crucial aspects of these flows such as the timing, magnitude, and duration of key hydrological events. Our goal was to develop an analytical framework that can support practical hydrological management of wetlands such as the Baiyangdian Wetland based on seeking a feasible compromise between human and ecological needs.…”