1. Hydrologic Concepts

2. Hydrologic Dimensions and Units The fundamental dimensional character of quantities encountered in this course (and all of hydrology) can be expressed as: M = mass L = length T = time Θ = temperature F = force

3. Hydrologic Dimensions and Units M = a measure of the amount of matter contained in a given quantity of material kg; 1 kg = 1000 g; 1 g =1000 mg L = linear measure of distance m; 1 m = 100 cm; 1 km = 1000 m T = passage of time measured in terms of motion or displacement of bodies in space sec; 1 yr = 365 day; 1 day = 24 hr; 1 hr = 60 min, 1 min =60 sec Θ = measure of the amount of molecular kinetic energy ("heat”) contained within a substance °C; °F F = the push or pull action on an object N (newton); 1 N = 1 kg-m/s 2 =1 kg-ms -2

4. Hydrologic Dimensions and Units meter (m) foot (ft) square meters (m 2) square feet (ft 2 ) cubic meters (m 3) cubic feet (ft 3 ) 1-dimensional 2-dimensional 3-dimensional

5. Some common hydrologic units: Stream velocity = change in position over time m 2 /second or ft 2 /second Discharge = flow rate of water m 3 /second or ft 3 /second Density = mass/volume kg/m 3 Hydrologic Dimensions and Units

6. Suppose the streamflows for two days were 1,020 ft 3 /sec and 3 ft 3 /sec. What is the total volume of water for the two days? Hydrologic Dimensions and Units

7. SI (System International) (or Metric) vs. English system Conversions between units (feet to meters or cubic feet to cubic meters) will be an important part of this class For example, I may want you to convert meters to feet Or pounds to kilograms Or ft 2 /sec to m 3 /sec Or ft 3 /sec to m 3 /sec Or °C to °F Hydrologic Dimensions and Units

8. See handout of conversions Let’s try some examples How many meters are in 10 feet? How many miles are 1,000 kilometers? How many seconds are in 2 years? How many acres in 5 square miles? What is 10 m 3 /s in ft 3 /s? Hydrologic Dimensions and Units

9. HYDROLOGY | watershed | definition “A watershed is an extent or an area of land here surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another water body, such as river, lake, reservoir, wetland, sea, or ocean” Also known as: Catchment Catchment area Catchment basin Drainage area River basin Water basin

13. HYDROLOGY | watershed | US hydrologic regions

14. 1.Region 21 nationally HYDROLOGY | watershed | hydrologic classification 2. Sub-region 221 nationally 3. Basins 378 nationally 4. Sub-basins 2246 nationally 700 square miles average area 4. Watershed 5-15 per sub- basin 5. Sub-watershed 5-15 per watershed

15. Ohio River Watershed

23. YOUR TURN!