PPT-Hydrograph Analysis

71 Components of a natural hydrograph The various contributing components of a natural hydrograph are shown in figure 71 To begin with there is baseflow only that is the groundwater contribution from the aquifers bordering the river which go on discharging more and more slowly with time The hydrograph of baseflow is near to an exponential curve and the quantity at any time is represented very nearly by. Reading: Applied Hydrology Sections 8.1, 8.2, 8.4. 2. Flow Routing. Procedure to determine the flow hydrograph at a point on a watershed from a known hydrograph upstream. As the hydrograph travels, it. Residence Time. Mean Water Residence Time (aka: turnover time, age of water leaving a system, exit age, mean transit time, travel time, hydraulic age, flushing time, or kinematic age). T. . = V. . Reading: Sections 7.1-7.3, 7.5, 7.7, . Hydrologic Analysis. Change in storage w.r.t. time = inflow - outflow. In the case of a linear reservoir, . S = kQ. Transfer function for a linear system (S = kQ).. Rami. . Harfouch. Surface Water Hydrology. University of Texas at Austin, April 2010. Peak flows (flood applications, channels design). Rationale method Q=C . i. A. Hydrograph (storage structures design). From Mays, 2011, Ground and Surface Water Hydrology. See tabulated values in Mays Table 8.8.1. Example. A watershed has 40% residential (1/4 ac lots), 25% open space (good condition), 20% commercial and business (85% impervious) and 15% industrial (72% impervious) with corresponding soil groups of C, D, C and D. . the Onion . Creek Watershed. Laura . Gundlach. Effects of Urbanization on the Hydrograph . Increased Impervious Cover and Improved Drainage Systems cause:. Higher . Peak . Flows. Shorter . Lag . Times. Soil Water. Precipitation and Evaporation. Infiltration, Streamflow, and Groundwater. Hydrologic Statistics and Hydraulics. Erosion and Sedimentation. Soils for Environmental Quality and Waste Disposal . CE 365K Hydraulic Engineering Design. Spring . 2016. Watersheds upstream of Dam 6. Subbasin. BUT_060. Flow along the longest path. Sheet Flow. Shallow Flow. Channel . Flow.  . Sum travel times over each segment. Bucket. Recording gage. Collector and Funnel. Bucket and Recorder. Accurate to .01 ft. Telemetry- computer. From . Bedient. Interpretation of storm rainfall records. From Mays, 2011, Ground and Surface Water Hydrology. on streams throughout the USA. Tonia Hack. William Sanford. Department of Geosciences. Colorado State University. Separate hydrograph using 2-component end member mixing. Estimate . baseflow. Compare to analytical methods: fixed interval, sliding interval, local minimum. 2. Flow Routing. Procedure to determine the flow hydrograph at a point on a watershed from a known hydrograph upstream. As the hydrograph travels, it. attenuates . gets delayed. Q. t. Q. t. Q. t. Q. t. Hydrologic Analysis. Change in storage w.r.t. time = inflow - outflow. In the case of a linear reservoir, . S = kQ. Transfer function for a linear system (S = kQ).. Proportionality and superposition. From Mays, 2011, Ground and Surface Water Hydrology. A D hour unit hydrograph is the characteristic response of a given watershed to a unit volume (e.g. 1 in or cm) of effective water input (usually rain) applied at a constant rate for D hours. HYDROGRAPHS. A hydrograph is a continuous graph showing the properties of stream flow with respect to time. Normally obtained by means of a continuous strip recorder that indicates stage versus time (stage hydrograph) and is then transformed to discharge hydrograph by use of rating curve..