GEO 155 1st Edition Lecture 19 Last Lecture Hydrology Outline of Current Lecture I Hydrology and Hydrographs a Stage and Discharge b Short term Hydrograph c Annual Hydrograph d Slides Current Lecture Stage and Discharge Flood Stage How high is the water Shows different amounts of water Discharge Q Measured in feet cubed per seconds Volume of water in a channel at a certain time These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Hydrograph The graph of a given amount of water in a river at a given time Q vs T Short term Hydrograph Overland Flow Short base flow High flood peak large flooding Short lag time between rainstorm and flood Short duration rapid hydrologic response to rain storm o High peak means water moved quickly across the landscape and got to the stream channel quickly and all at once Steep topography Sparse vegetation Intense precipitation Frozen ground Shallow fine soil Typical of urban settings High Infiltration High base flow Low flood peak Long lag Long duration Slow hydrologic response o More water at ground water allows for a higher water table contributing to higher base flow Deep soil Dense vegetation Gentle topography Etc Typical of rural Farming Pre development before settlers came there was more infiltration Post development settlers began using straight row plowing creating more overland flow In between the two peaks contour plowing made overland flow harder Annual Hydrograph How discharge changes over the course of a year More Overland Flow Low Base flow Ephemeral Flow no base flow Not enough water table in the desert to reach the stream channels Northern Hemisphere Tropical Wet and Dry Northern Hemisphere Mediterranean Peak flooding in winter Mountainous Environments Mountainous environments have one peak flooding during the snow melt of spring
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