Legacy effects of past land use and disturbance are increasingly recognized, yet consistent definitions of and criteria for defining them do not exist. To address this gap in biological- and ecosystem-assessment frameworks, we propose a general metric for evaluating potential legacy effects, which are computed by normalizing altered system function persistence with duration of disturbance. We also propose two distinct legacy-effect categories: signal effects from lags in transport and structural effects from physical landscape changes. Using flux records for water, sediment, nitrogen, and carbon from long-term study sites in the eastern United States from 1500 to 2000, we identify gaps in our understanding of legacy effects and reveal that changes in basin sediment dynamics precede instrumented records. These sediment dynamics are not generally incorporated into interpretations of contemporary records, although their potential legacy effects are substantial. The identification of legacy effects may prove to be a fundamental component of landscape management and effective conservation and restoration practice.
Bain, D.J., Green, M.B., Campbell, J.L., Chamblee, J.F., Chaoka, S., Fraterrigo, J.M., Kaushal, S., Martin, S.L., Jordan, T.E., Parolari, A.J., Sobczak, W.V., Weller, D.E., Wollheim, W.M., Boose, E., Duncan, J.M., Gettel, G.,.pdf
Forests cover approximately one third of the global land surface area. Changes induced by human activities can exert significant impacts on the environmental services provided by forests. Nevertheless, the long term footprints of certain types of forest cover conversions on the water and biogeochemical cycles are poorly understood. My research work has focused on observing and predicting hydrological processes in managed forested ecosystems. This is, how the disturbance and recovery of forests can affect the components of the water balance.
Currently, I am investigating the potential effects on the water quantity and quality of the Great Lakes Basin from on-going environmental changes as the intensive development of biofuel crops in the Midwestern United States. I am also involved in the large-scale assessment of the Ogallala-High Plains aquifer, one of the largest aquifers in the world, from a sustainability approach that combines climate, economic, social, crop, and hydrological models. A third topic of my research concerns the observation and modeling of subsurface processes using geophysical methods.
Moreover, I am also interested on additional topics as ecohydrology, desertification, nonlinear patterns in geophysics, climate change and infrastructure and, water management systems.
- Ph.D. Forestry and Environmental Sciences, University of Freiburg, Germany. 2012. Dissertation Title: The hydrology of forest disturbance and succession during dry periods.
- M.A.S. Water resources engineering and management, Swiss Federal Institute of Technology Lausanne/Zurich, Switzerland. 2007. Thesis Title: On the sensitivity analysis of the PMF to the space-time distribution of a PMP: Analysis of the hydrological response of a catchment.
- B.Eng. Hydrological engineering, Metropolitan Autonomous University, Mexico. 2005.
- Brena A, Stahl K and Weiler M (2011) Evapotranspiration and land cover transitions: long term watershed response in recovering forested ecosystems. Ecohydrology DOI: 10.1002/eco.256
- Brena A, Weiler M and Stahl K (2011) The sensitivity of a data-driven soil water balance model: insights from
a successional chronosequence. Hydrology and Earth System Sciences Accepted.
- Brena A, Stahl K and Weiler M. 2011. How does forest disturbance and succession affect summer streamflow recession?, AGU Fall Meeting, San Francisco, USA.
- Brena A, Weiler M and Stahl K. 2011. Predicting evapotranspiration in a successional forest without eddy covariance measurements, EGU General Assembly, Vienna, Austria.
- Brena A, Weiler M, Stahl K and Smith R. 2010. Comparative ecohydrology across disturbed forested watersheds: soil moisture regimes and storage-discharge relationships, LATSIS Symposium. Lausanne, Switzerland.
- Brena A, Weiler M and Stahl K. 2010. Inferring long-term water balance dynamics in forested watersheds: tracing vegetation cover transitions, EGU General Assembly, Vienna, Austria.
- Gaume E, Bain V, Marchi L, Preciso E, Bass S, Brena A, Borga M, Bonnifait L, Horvat O, Rogga M, Stegmeier A, Schütz T and Viglione A. 2009. An intensive Post Event Campaign (IPEC) on the extreme flash flood which affected the Starzel river (Germany) on the 2nd of June 2008, EGU General Assembly, Vienna, Austria.
- Brena A, Schneider J, Stahl K. and Weiler M. 2009. Estimation of low flows sensitivity to climate and land use changes using a parsimonious water balance model, EGU General Assembly, Vienna, Austria.
- Brena A,. 2006. Strategies for flood prediction in large urban zones, 2nd International Symposium “Preventing and Fighting Hydrological Disasters”, Timisoara, Romania.
- Brena A, and Briseno F. 2005. Strategies for flood prediction in large urban zones, 4th Worldwide Workshop for Young Environmental Scientists CEREVE-UNESCO-IWA, Paris, France.
- Brena A,. 2003. Managing Urban Development and Industrial Growth in the Basin of Mexico, 13th Stockholm Water Symposium, Stockholm, Sweden.
A new post-doc, Agustin Brena, joins the Hydrogeology Lab
Groundwater models coupled with GIS analyses can be used to estimate the time for groundwater and solutes to be transported from each location across a watershed to surface water bodies. Coupled to backcast land use models, these estimates can be used to create land use “legacy” maps that quantify the contribution of historic land uses to the groundwater signal arriving at streams. However, groundwater models and backcast land use models contain uncertainties inherent to each model. These uncertainties may affect the outcome of the coupled model and hence their reliability to natural resource and land use planning. In this paper we demonstrate how a simple spatially explicit, multi-uncertainty metric can be used to assess uncertainties from our backcast land use change and groundwater travel time model. We couple five variants of groundwater travel time (GWTT) simulations with 12 variants of historic land uses, and analyze the resulting 60 realizations of land use legacy maps using a spatially explicit, multi-metric uncertainty score. We apply this approach to the Muskegon River Watershed in Michigan, where groundwater flow provides the vast majority of streamflow. Our results indicate that despite uncertainties inherent in both models, townships located in the north-central portion of the study watershed can benefit from using legacy maps as planning tools despite a wide range of evaluated uncertainties.
Ray et al Lecacy uncertainties – Applied Geography 2012
My research focuses on developing source models for nutrient loading to watersheds in the lower peninsula of Michigan. Watershed nutrient loading models are important tools used to address issues including eutrophication, harmful algal blooms, and decreases in aquatic species diversity. A source specific model will help show the value of detailed source inputs, revealing regional trends while still providing insight to the existence of variability at smaller scales.
I have additional interest and background in groundwater management, characterization, and prediction for mining projects and contaminated sites.
Dartmouth College, 2008 BA
Luscz E.C., Kendall, A.D., Martin, S.L., Hyndman, D.W. (2011): Modeling Nutrient Loading to Watersheds in the Great Lakes Basin: A Detailed Source Model at the Regional Scale, AGU Fall Meeting, San Francisco
Breckenridge, James Larry; Luscz, Emily (2011): Predicting Underground Mine Dewatering Requirements: A Case Study of a Precious Metal Mine in a Subtropical Environment. – In: Rüde, R. T., Freund, A. & Wolkersdorfer, Ch.: Mine Water – Managing the Challenges. – p. 101 – 105; Aachen, Germany.
Watershed nutrient loading models are important tools used to address issues including eutrophication, harmful algal blooms, and decreases in aquatic species diversity. Such approaches have been developed to assess the level and source of nutrient loading across a wide range of scales, yet there is typically a tradeoff between the scale of the model and the level of detail regarding the individual sources of nutrients. To avoid this tradeoff, we developed a detailed source nutrient loading model for every watershed in Michigan’s lower peninsula. Sources considered include atmospheric deposition, septic tanks, waste water treatment plants, combined sewer overflows, animal waste from confined animal feeding operations and pastured animals, as well as fertilizer from agricultural, residential, and commercial sources and industrial effluents . Each source is related to readily-available GIS inputs that may vary through time. This loading model was used to assess the importance of sources and landscape factors in nutrient loading rates to watersheds, and how these have changed in recent decades. The results showed the value of detailed source inputs, revealing regional trends while still providing insight to the existence of variability at smaller scales.
Conventional characterization methods can be combined with Gaussian geostatistical methods to develop 3D hydraulic conductivity (K) fields for sites with low levels of heterogeneity. Parameterization of K fields for flow and transport modeling in highly heterogeneous aquifers, however, remains challenging. Novel stochastic and geostatistical methods have been proposed to improve simulations of highly heterogeneous K fields, but these generally rely on in-situ measurement methods that are invasive, provide limited spatial sampling, and have large support volumes with unknown geometries. We present fully conditional fractal simulations to faithfully synthesize 3D non-Gaussian K fields at the Macro Dispersion Experiment (MADE) site. Full-resolution ground penetrating radar data were used for soft conditioning, to separate hydrologically distinct facies. High-resolution K data from a novel Direct Push tool were then used for hard conditioning and estimation of required facies parameters, including fractal dimensions and correlation lengths. The resulting 3D K fields were used in a flow and transport model. These simulations reproduced the long tailed behavior of observed concentration histories, characteristic of tracer tests at the MADE site.
Full‐resolution 3D Ground‐Penetrating Radar (GPR) data were combined with high‐resolution hydraulic conductivity (K) data from vertical Direct‐Push (DP) prof i l es to characterize a por t ion of the highly heterogeneous MAcro Dispersion Experiment (MADE) site. This is an important first step to better understand the influence of aquifer heterogeneities on observed anomalous transport. Statistical evaluation of DP data indicates nonnormal distributions that have much higher similarity within each GPR facies than between facies. The analysis of GPR and DP data provides high‐resolution estimates of the 3D geometry of hydrostratigraphic zones, which can then be populated with stochastic K fields. The lack of such estimates has been a significant limitation for testing and parameterizing a range of novel transport theories at sites where the traditional advection‐dispersion model has proven inadequate.