How to Calculate Water Storage Capacity of a Pond?

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How can I calculate the capacity of a lake for storing water?

I know there is a simple equation to calculate the lake water volume using the Frustrum Method: 

lake formula.png

V = volume of water;
H = difference in depth between two successive depth contours;
A1 = area of the lake within the outer depth contour being considered;
A2 = area of the lake within the inner contour line under consideration. 


Which other methods can you suggest for calculations for lakes with slopes? Which method will best take the slope into account and yet remain simple? 

Is there a software or an app to estimate the storage capacity of the lake? 

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6 Answers

  1. Different Type of Pond Shape,

    1. Circular.
    2. Rectangular or Square,
    3. Trapezoid
    4. Irregular shape
    1. Average Length and Width Method:  Take numerous measurements to determine the average length and average width. Make certain you get both the longest and shortest distances in calculating the average length, and the widest and narrowest distances for determining the average width. The more measurements that you make, the more accurate your result will be. The area is then calculated by multiplying the average width times the average length.
    2. Multiple Trapezoids Method:  A more accurate method to determine the area of an odd-shaped pond is to divide the pond into multiple trapezoid shapes. A new trapezoid is defined anywhere the shoreline makes a rapid change in direction. Note that instead of horizontal transects, this method requires measurement of the distance between each vertical transect.
    3. Handheld Global Positioning Systems (GPS):  Handheld GPS systems have become quite common over the past five years as they have become more affordable. and navigation. GPS units allow you to determine your exact location on earth using multiple satellites in space. Various locations, or “waypoints,” can be stored in the GPS unit for use with mapping software that either accompanies the unit or can be purchased separately. The software can connect the waypoints and calculate the area inside the resulting shape.
    4. Geographical Information Websites:  There are also geographical information programs on the internet, like Google Earth or Bing Maps, which use satellite imagery to display a map of your pond or lake. These website tools can make it very easy to determine the surface area of your water resource.
    5. Another important measurement for a pond or lake manager to know is the “residence time” of your water resource. Residence time is how long water resides in the pond, from the time it enters the pond to the time it leaves through the spillway or overflow pipe. This calculation is important for making herbicide or liming applications to the pond. If water flows too quickly through your pond, it may not be effective to make these types of applications. 

  4. If the bottom area is relatively even and slope of sides is roughly 45 degr. (as is often the case) you could just calculate volume based om bottom area, then calculate volume based on water surface area (top). Subtract the two volumes and divide by two, there you have the volume of the sides, then add or subtract that from either volume. But this is very rough of course.....

  5. AutoCAD Civil 3D or equivalent can also be used to derived pond storage volume.