North Peoria Area Drainage Master Plan - Flood Control District of ...

NORTH PEORIAAREA DRAINAGE MASTER PLANfrom the HEC-RAS models, sediment yieldestimates, and size gradations as previouslydiscussed, and on the in-flow hydrographs.Initial model development and verificationwill be prepared for a test reach. Upon satisfactoryverification of the proposed modelingtechnique, HEC-6 models will be developed ina similar manner for the other study reaches.• Measure historical channel characteristics(width, sinuosity, etc.).• Plot and compare historical longitudinalprofiles.• Catalogue types of human impacts, plotlocations.Task 2 – Lateral Stability AssessmentInterpretation of Geologic Surfaces. Geologicdata will be used to identify and map recentgeomorphic surfaces near the stream. The ageand position of these surfaces will be used toconstrain the rate of lateral and vertical movementover recent geologic time. Specific tasksinclude the following:• Interpret aerial photographs.• Select soil test pit locations.• Describe soil profiles in soil test pits.• Describe surficial soil characteristics.• Inspect surfaces in field.• Prepare geomorphic mapping.Historical Analyses. Historical data will beused to identify historical patterns of channelbehavior, historical impacts on the stream byhumans, and past rates of lateral and verticalchannel change. Historical data will be usedto set the context for interpretation of existingconditions and prediction of future channelresponse. Specific tasks include the following:• Collect historical maps and topography.• Collect historical aerial and ground photographs.• Digitize historical channel position.• Determine rates and types of channelchange from digitized channel plots.• Prepare time line of watershed and channelchanges.Field Analyses. Field data will be collected toidentify areas of channel instability, quantifychannel and bank characteristics, and documentexisting channel conditions. Specifictasks include the following:• Select index cross section spacing andlocations.• Measure channel characteristics at indexcross sections.• Measure bank characteristics at indexcross sections.• Document existing conditions with photographsand notes.• Perform boulder counts for channel bedsediments.• Describe soil pits excavated in the channelbottom.• Collect sediment samples from the channelbottom for sieve analysis.Geomorphic Analysis. A geomorphic descriptionof the stream characteristics will be preparedto identify appropriate types ofhydraulic and empirical analyses, identifyexisting channel processes, and to predicttrends in future channel behavior. Specifictasks include the following:• Describe regional geologic history.30