Multiscale modeling for watershed management using GIS
Helena Mitasova, Geographic Modeling Systems Laboratory, Department
of Geography,
220 Davenport Hall, University of Illinois at Urbana-Champaign, Urbana,
IL 61801, USA, ph:
217-333-4735, fax:217-244-1785, email: helena@gis.uiuc.edu
Douglas Johnston, Geographic Modeling Systems Laboratory, National Center
for Supercomputing Applications, 220 Davenport Hall, University of Illinois
at Urbana-Champaign, Urbana, IL 61801, USA, ph: 217-333-5880,
fax:217-244-1785, email: dmj@ncsa.uiuc.edu
Lubos Mitas, National Center for Supercomputing Applications, 405 N.
Mathews Ave, University of
Illinois at Urbana-Champaign, Urbana, IL 61801, USA
William M. Brown, Geographic Modeling Systems Laboratory, Department
of Geography, 220
Davenport Hall, University of Illinois at Urbana-Champaign, Urbana,
IL 61801, USA
Increasing pressures on the environment lead to profound changes
in land management approaches. Community based efforts are becoming more
common, enhancing the effectiveness of federal conservation measures.
To ensure the success of this approach landowners and managers need
to be provided with sufficient knowledge about their watershed and its
internal behavior. Computational and information technology provides valuable
tools for development and communication of this knowledge, creating conditions
for a long term sustained commitment. Models of watershed behavior demonstrating
how the lands within the watershed are connected, how they interact and
influence each other help to build sense of shared ownership necessary
for successful sustainable land management programs. Community based approach
involves coordination between a diverse group of individuals and agencies
which view and manage the landscape at different scales. The evaluation
of the impact of numerous, locally implemented conservation practices on
the entire watershed requires multiscale approach which links the high
resolution/landowner level simulation with the low resolution/regional
simulation. To better support the multilevel watershed management we propose
a methodology for watershed characterization and modeling at
multiple scales and levels of complexity.
We describe our efforts in GIS supported hydrologic and erosion simulations, which aim to fulfill some of the needs of multiscale approach, using the case study of the Court Creek Pilot Watershed Program supported by the Illinois Department of Natural Resources. To better understand the current situation in the watershed and possible impacts of planned conservation measures, we are using our set of modeling tools for assessment of water flow, sediment transport and net erosion/deposition patterns with increasing level detail and complexity. First, we have used the GIS-based, modified USLE model to illustrate a low cost, approximate evaluation of overland erosion risk. The analysis based on publicly available, relatively low resolution data indicates that headwater areas are less protected against erosion than the areas along the bigger streams. Based on the analysis for the entire watershed, we have identified two subwatersheds as "high risk" and performed a more detailed study. We have estimated the detachment limited erosion by modified USLE and a potential for net erosion and deposition for transport capacity limited erosion using the USPED model. Combined overland flow and stream modeling (to be performed in cooperation with Illinois State Water Survey) will allow us to evaluate how much impact have the upland and headwater areas on downstream problems and whether improved protection in these areas could reduce flooding, bank erosion and sediment loads. While the process-based SIMWE model was developed to model erosion processes, its hydrologic submodel supports simulation of water depth in depressions and flat areas allowing us to identify those locations which have natural topographic conditions for wetlands. We have simulated water depth from shallow overland flow (without the impact of channels/streams) to find the areas which can accumulate and hold enough water from surface flow . According to the wetland inventory data, the selected high risk subwatersheds have only 0.32% area covered by wetlands, however the model indicates that terrain configuration has natural conditions for 2.5% area for wetlands, especially in flatter locations and depressions along the streams.
Communication of results to the participants involved in watershed management
is challenging due to the varied backgrounds and complexity of analysis.
We rely heavily on advanced visualization tools to represent the spatial
distribution of processes and outcomes. Work in multidimensional
visualization and virtual reality applications is reported.