Comparing flow regime, channel hydraulics, and biological communities to infer flow–ecology relationships in the Mara River of Kenya and Tanzania

McClain, Michael E.; Subalusky, Amanda L.; Anderson, Elizabeth P.; Dessu, Shimelis Behailu; Melesse, Assefa M.; Ndomba, Preksedis M.; Mtamba, Joseph; Tamatamah, Rashid; Mligo, Cosmas

doi:10.1080/02626667.2013.853121

Cited by 70 publications

(63 citation statements)

References 46 publications

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“…Where the hydrology and morphology of rivers perform economically essential functions, an alternative objective of good ecological potential (GEP) can be followed, provided other criteria are met. In many developing countries, there is a more explicit link between the ecological benefits of environmental flows and the livelihoods of rural subsistence users of the river, such as in the Okavango basin (King et al 2014), Mara River (McClain et al 2014), Rufiji River (Duvail et al 2014) and River Mekong (Thompson et al 2014).…”

Section: Setting Objectivesmentioning

confidence: 99%

“…Local and scientific knowledge regarding the floodplains and lakes on the Lower Rufiji, Tanzania, for instance, was critical to environmental flow assessment for that river (Duvail et al 2014). Likewise, integrating science, expert knowledge and stakeholder participation has been fundamental to assessing environmental flows for the Mara River basin of East Africa (McClain et al 2014) and assessing them for the Okavango River system (King et al 2014).…”

Section: Evidence and Uncertaintymentioning

confidence: 99%

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The changing role of ecohydrological science in guiding environmental flows

Acreman

Overton

King

et al. 2014

Hydrological Sciences Journal

134

122

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The term "environmental flows" is now widely used to reflect the hydrological regime required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on them. The definition suggests a central role for ecohydrological science to help determine a required flow regime for a target ecosystem condition. Indeed, many countries have established laws and policies to implement environmental flows with the expectation that science can deliver the answers. This article provides an overview of recent developments and applications of environmental flows on six continents to explore the changing role of ecohydrological sciences, recognizing its limitations and the emerging needs of society, water resource managers and policy makers. Science has responded with new methods to link hydrology to ecosystem status, but these have also raised fundamental questions that go beyond ecohydrology, such as who decides on the target condition of the ecosystem? Some environmental flow methods are based on the natural flow paradigm, which assumes the desired regime is the natural "unmodified" condition. However, this may be unrealistic where flow regimes have been altered for many centuries and are likely to change with future climate change. Ecosystems are dynamic, so the adoption of environmental flows needs to have a similar dynamic basis. Furthermore, methodological developments have been made in two directions: first, broad-scale hydrological analysis of flow regimes (assuming ecological relevance of hydrograph components) and, second, analysis of ecological impacts of more than one stressor (e.g. flow, morphology, water quality). All methods retain a degree of uncertainty, which translates into risks, and raises questions regarding trust between scientists and the public. Communication between scientists, social scientists, practitioners, policy makers and the public is thus becoming as important as the quality of the science. lois et des politiques de mise en oeuvre de débits environnementaux en espérant que la science peut fournir les réponses. Ce document donne un aperçu des développements et des applications récents de débits environnementaux sur les six continents dans le but d'explorer l'évolution du rôle des sciences éco-hydrologiques, en reconnaissant leurs limites et les nouveaux besoins de la société, des gestionnaires des ressources en eau et des décideurs politiques. La science a répondu par de nouvelles méthodes pour relier l'hydrologie à l'état des écosystèmes, mais à cette occasion des questions fondamentales ont été soulevées qui vont au-delà de l'éco-hydrologie, telles que : qui décide de l'état souhaité pour un écosystème ? Certaines méthodes de débits environnementaux sont basées sur le paradigme de l'écoulement naturel, ce qui suppose que le régime souhaité est la condition naturelle « non modifiée ». Cela peut être irréaliste là où les régimes d'écoulement ont été modifiés pendant de nombreux siècles et sont susceptibles d'évoluer avec le changement climatique ...

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Section: Setting Objectivesmentioning

confidence: 99%

Section: Evidence and Uncertaintymentioning

confidence: 99%

The changing role of ecohydrological science in guiding environmental flows

Acreman

Overton

King

et al. 2014

Hydrological Sciences Journal

134

122

View full text Add to dashboard Cite

show abstract

“…In the Mara River case study, a review of land use and land cover (Mati et al, 2008;Atisa et al, 2014), hydrology (Mango et al, 2011;McClain et al, 2014), the vision for the case study, current and future land and water resource use options and socio-ecological importance (Karanja, 2002;LVBC and WWF-ESARPO, 2010;Mango et al, 2011;GLOWS-FIU, 2012;Dessu et al, 2014;Dutton et al, 2013) was used to select risk regions. Ten risk regions were selected for the Mara River case study which conformed to catchment boundaries, ecoregions, land use practices and the international boundary (Fig.…”

Section: Step 3: Risk Region Selectionmentioning

confidence: 99%

“…The Mara River case study (refer to Table S1) was based on existing data from historical surveys (Mati et al, 2008;McCartney, 2010;Majule, 2010;LVBC and WWF-ESARPO, 2010;Mango et al, 2011;Kanga et al, 2011;GLOWS-FIU, 2012;Dutton et al, 2013;Atisa et al, 2014;Gichana et al, 2014;Kilonzo et al, 2014;McClain et al, 2014) and a single site visit to refine the CPTs (NBI, 2016). During this survey seven sites were selected to represent the variability of all of the RRs in the study area.…”

Section: Mara River Risk Calculationmentioning

confidence: 99%

A regional-scale ecological risk framework for environmental flow evaluations

O’Brien

Dickens

Hines

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Environmental flow (E-flow) frameworks advocate holistic, regional-scale, probabilistic E-flow assessments that consider flow and non-flow drivers of change in a socioecological context as best practice. Regional-scale ecological risk assessments of multiple stressors to social and ecological endpoints, which address ecosystem dynamism, have been undertaken internationally at different spatial scales using the relative-risk model since the mid-1990s. With the recent incorporation of Bayesian belief networks into the relativerisk model, a robust regional-scale ecological risk assessment approach is available that can contribute to achieving the best practice recommendations of E-flow frameworks. PROBFLO is a holistic E-flow assessment method that incorporates the relative-risk model and Bayesian belief networks (BN-RRM) into a transparent probabilistic modelling tool that addresses uncertainty explicitly. PROBFLO has been developed to evaluate the socio-ecological consequences of historical, current and future water resource use scenarios and generate E-flow requirements on regional spatial scales. The approach has been implemented in two regional-scale case studies in Africa where its flexibility and functionality has been demonstrated. In both case studies the evidence-based outcomes facilitated informed environmental management decision making, with trade-off considerations in the context of social and ecological aspirations. This paper presents the PROBFLO approach as applied to the Senqu River catchment in Lesotho and further developments and application in the Mara River catchment in Kenya and Tanzania. The 10 BN-RRM procedural steps incorporated in PROBFLO are demonstrated with examples from both case studies. PROBFLO can contribute to the adaptive management of water resources and contribute to the allocation of resources for sustainable use of resources and address protection requirements.

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“…The Mara mines and Kirumi ferry gauging stations have been in operation since 1969. The other stations were specifically installed to support the flood modeling and understanding reach-scale hydraulics in 2011-2013 [47,48]. The figure below shows historical gauging stations and temporary stations for hydraulic study (1)(2)(3)(4).…”

Section: Study Areamentioning

confidence: 99%

Use of Radarsat-2 and Landsat TM Images for Spatial Parameterization of Manning’s Roughness Coefficient in Hydraulic Modeling

et al. 2015

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Vegetation resistance influences water flow in floodplains. Characterization of vegetation for hydraulic modeling includes the description of the spatial variability of vegetation type, height and density. In this research, we explored the use of dual polarized Radarsat-2 wide swath mode backscatter coefficients (σ°) and Landsat 5 TM to derive spatial hydraulic roughness. The spatial roughness parameterization included four steps: (i) land use classification from Landsat 5 TM; (ii) establishing a relationship between σ° statistics and vegetation parameters; (iii) relative surface roughness (Ks) determination from Synthetic Aperture Radar (SAR) backscatter temporal variability; (iv) derivation of the spatial distribution of the spatial hydraulic roughness both from Manning's roughness coefficient look up table (LUT) and relative surface roughness. Hydraulic simulations were performed using the FLO-2D hydrodynamic model to evaluate model performance under three different hydraulic modeling simulations results with different Manning's coefficient parameterizations, which includes SWL1, SWL2 and SWL3. SWL1 is simulated water OPEN ACCESSRemote Sens. 2015, 7 837 levels with optimum floodplain roughness (np) with channel roughness nc = 0.03 m −1/3 /s; SWL2 is simulated water levels with calibrated values for both floodplain roughness np = 0.65 m −1/3 /s and channel roughness nc = 0.021 m −1/3 /s; and SWL3 is simulated water levels with calibrated channel roughness nc and spatial Manning's coefficients as derived with aid of relative surface roughness. The model performance was evaluated using Nash-Sutcliffe model efficiency coefficient (E) and coefficient of determination (R 2 ), based on water levels measured at a gauging station in the wetland. The overall performance of scenario SWL1 was characterized with E = 0.75 and R 2 = 0.95, which was improved in SWL2 to E = 0.95 and R 2 = 0.99. When spatially distributed Manning values derived from SAR relative surface values were parameterized in the model, the model also performed well and yielding E = 0.97 and R 2 = 0.98. Improved model performance using spatial roughness shows that spatial roughness parameterization can support flood modeling and provide better flood wave simulation over the inundated riparian areas equally as calibrated models.

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Comparing flow regime, channel hydraulics, and biological communities to infer flow–ecology relationships in the Mara River of Kenya and Tanzania

Cited by 70 publications

References 46 publications

The changing role of ecohydrological science in guiding environmental flows

The changing role of ecohydrological science in guiding environmental flows

A regional-scale ecological risk framework for environmental flow evaluations

Use of Radarsat-2 and Landsat TM Images for Spatial Parameterization of Manning’s Roughness Coefficient in Hydraulic Modeling

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