Nandita Basu

Assistant Professor
Civil and Environmental Engineering
Earth and Environmental Sciences
University of Waterloo
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Monsoon Harvests

Dynamics of Hormone Loads and Attenuation in Ditches and Streams

Passive Surface Water Flux Meter (PSFM)

Hydrologic Connectivity of Drained (Farmed) Wetlands in Iowa’s Prairie Pothole Landscape

Hydrologic Impacts of Artificial Drainage

People, Water and Climate

Remote Sensing Based Distributed Hydrologic Modeling















































































































































































Monsoon Harvests:

Dynamics of Hormone Loads and Attenuation in Ditches and Streams

This is a collaborative project between Purdue University and University of Iowa, and funded by USDA, to study the environmental fate and transport of synthetic and natural hormones from land application of animal manures generated by concentrated animal feeding operations (CAFOs). Concentrations of hormones sufficient to invoke impacts on aquatic species
have been detected in the ditch network receiving tile drainage and surface run off from fields fertilized with animal manure and associated lagoon effluent.
However, the propagation of this hormone load into the watershed into which the ditch network flows is not well understood. Our overall goal is to evaluate persistence of hormones in ditch-stream networks and how they may propagate in the stream network by achieving the following four objectives:
(1) Develop a “source function” module to predict the hormone mass available for transport to ditches via subsurface tile-drains or surface runoff;
(2) Assess legacy hormone loads accumulated in ditches receiving tile drainage and runoff;
(3) Assess in-stream biogeochemical processes attenuating hormones during transport; and
(4) Predict and validate what hormone loads will be transported in the stream network beyond the source area.

Passive Surface Water Flux Meter (PSFM)

Much research in watersheds is aimed at describing spatially distributed processes while telescoping monitoring efforts towards a single point of interest, the watershed outlet. Developing spatially distributed models that are calibrated against such spatially integrated measurements often leads to equifinality and non-uniqueness issues.
The need for spatially distributed data in multiple first order streams within a watershed is well recognized, but often not practiced due to cost and practical considerations. We are designing a Passive Surface Water Flux Meter (PSFM) to get better spatial data. The PSFM is a low-cost, flow integrated stream water quality sampler designed to provide estimates of cumulative water and solute fluxes across a stream cross-section over the deployment period (~ 3 to 5 days). The device is composed of sorbent that captures the solute of interest (eg, nitrate, pesticides,
horm.ones) and extracting the sorbent post deployment is used for estimating the cumulative solute flux. Simultaneously, pre-sorbed alcohol tracers are eluted in proportion to streamflow, and provide estimates of water flux. Temporal resolution within a storm is sacrificed in order to get better spatial coverage over the watershed.

Hydrologic Connectivity of Drained (Farmed) Wetlands in Iowa’s Prairie Pothole Landscape

The Prairie Pothole Region (PPR) is a vast area of glacially formed depressional wetlands that extends from Alberta to Minnesota, with the southern tip reaching into Iowa (Figure 1). The portion of the PPR that extends into Iowa is known as the Des Moines Lobe and covers an area of 3.5 million ha.
This region of the state is heavily farmed for the production of row crops, with more than 95-99% of the wetlands drained (farmed) for agricultural use. Despite efforts by producers to “dry out” these wetlands by drainage using subsurface tiles, many of them still flood during particularly wet periods when the tile capacity is exceeded (Figure 2), and often produce only marginal crop yields.
Restoration of these marginal farmed areas back to wetlands could provide a myriad of environmental benefits, including decreased flooding, improved water quality and habitat for waterfowl and other migratory birds. Little research has been done into the effect that this could have upon the environment, and while restoration works are ongoing it is difficult to understand how beneficial they may be, especially at the watershed scale.
Figure 1

Figure 2
 Studies have been primarily focused on individual wetlands, but the role of hydrologic connectivity of distributed wetlands in maintaining seasonal inundations is still mostly unknown. The overall objective of this project is to understand the dynamics of water storage in these systems, and use the understanding to develop a hydrologic model that adequately captures the surface and sub-surface water flow dynamics.



Hydrologic Impacts of Artificial Drainage

Following recent flooding, there has been renewed discussion regarding the impacts of drainage, specifically tile drainage, on streamflow hydrology. Due to the importance of drainage systems to agricultural productivity in Iowa there is a need to conduct a comprehensive assessment of the hydrologic impacts of drainage systems.

This research brings together a team of researchers from the two major Universities in the state of Iowa, The University of Iowa (UI) and Iowa State University (ISU), with complementary expertise in drainage systems in terms of watershed modeling and observational data. Our effort will utilize state-of-the-art knowledge and modeling tools coupled with selective observations to fill a critical gap in understanding the extent to what degree artificial drainage has changed surface and subsurface water storage, residence times, flow duration, and peak flows within river basins here in Iowa over the last century. We anticipate the application of physically based, coupled surface water/groundwater models (e.g., DRAINMOD, MIKE-SHE, GSSHA, Hydrogeosphere) to simulate these watershed systems.
The contributions of the proposed research program will be significant because 1) it will quantify the spatial and temporal heterogeneity of water fluxes in tile-drained landscapes from local to regional scales, 2) it will identify the factors affecting variability in storage, residence times, and pathways among parts of the hydrologic system and 3) it will perform research using a cross-disciplinary hydrology team that links two major universities in Iowa. We are currently hiring a Masters student for this project.

People, Water and Climate: Adaptation and Resilience in Agricultural Watersheds

This is a collaborative project between University of Iowa, Iowa State University and the Southern Illinois University, and funded by NSF Coupled Natural and Human Systems Program. The overall objective of this project is to develop a better understanding of the processes that link global-scale climate and socioeconomic drivers to regional-scale responses in land use decision making, water quality, and water quantity. We are currently hiring Masters and PhD level students on this project.

Remote Sensing Based Distributed Hydrologic Modeling in Midwestern Landscapes for Predicting “Tile-to-Tide” Responses

In this project, funded by the Center for Global, Regional and Environmental Research (CGRER), we are exploring the use of remote sensing (RS) products (MODIS) for developing parsimonious hydrologic models that can then be used in conjunction with water quality modules to evaluate impacts of dynamic land-use shifts under alternate energy production scenarios. The Threshold Exceedance Lagrangian Model (TELM) developed by Basu et al (2010) is unique in its ability to identify functionally homogeneous units in the watershed, and predict streamflow, without calibration, using hydrologic attributes specific to tile-drained Midwestern watersheds. Our overall objective is to enhance the parsimonious hydrologic model TELM by using remotely sensed vegetation data. The model RS-TELM will then be used for prediction of spatially distributed runoff patterns in watersheds across the state of Iowa.