Thanos Papanicolaou
IIHR - Hydroscience & Engineering, The University of Iowa

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Application Note: Watershed Studies
 
Watershed dynamics: Many watershed simulations today work in the batch world; an event is simulated based on a static set of field data.  If newer data become available, the simulation is simply rerun. For example, hydrodynamic and sediment transport simulations to predict geomorphologic changes within a stream and the impact of these changes to the aquatic life are conducted by considering a constant sediment input value from terrestrial sources such as roads, floodplains, and other natural occurring disturbances (i.e., landslides, fires).  As a result perturbations that exist in the system due to the spatial and temporal variability in the terrestrial sediment input are not accounted.  Very few applications use real time data even if the capability to do so is available.  A great effort has been recently devoted to run simulations faster than real time based on static data sets.  However, this is highly inefficient and leads to multiple sediment predictions that are conflicting when major events are predicted.  This lack of ability to dynamically inject data into simulations and other applications, as these applications execute, limits the analysis and the predictive capabilities of these applications.  The novel capabilities to be sought here are application simulations that can dynamically accept and respond to on-line field data and measurements and/or control such measurements.  This synergistic and symbiotic feedback control-loop between simulations and measurements is a novel technical direction that can open domains in the capabilities of simulations within watersheds that can facilitate the “capturing” of episodic catastrophic events. 
   
Infiltration and water quality: Infiltration, the entry of water into the soil through rainfall, snowmelt or irrigation, determines the amount of runoff as well as the supply of water in the soil. Infiltration is important in predicting surface runoff, water quality properties and hillside erosion.  Among the variables affecting runoff and soil retention of water are slope of hillside, soil type, land management, and rainfall intensity.  A study is currently carried out in the Clear Creek watershed to expand our knowledge on soil infiltration by performing for the first time detailed field experiments under different soil aggregate attributes, landforms and management conditions.  Sensor technology will be used to obtain measurements of infiltration and conductivity in a non-intrusive manner.  The study will lead to development of a versatile and robust method useful in TMDLs (total maximum daily loads) for measuring surface runoff and transport of contaminants.  Because the study includes extensive water quality sampling, it should reveal the amount of time required for the benefits of best management practices (BMP) programs to show up downstream.  This would be a great benefit to watershed planners who will apply BMP programs.  Over the long term, the study will be useful to farmers in the region interested in minimizing nutrient loss to surface waters as part of ongoing BMPs, and to the Iowa Department of Natural Resources in strategic planning to clean-up Iowa's surface waters.  The objectives of study are to prevent bank erosion, improve soil and water quality and help the NRCS.