Mass Curve
- The mass curve of rainfall is a plot of the accumulated precipitation against time,plotted in chronological order.
- Records of float type, weighing bucket type etc raingauges are of this form.
- It gives information on duration and magnitude of a storm.
- Intensity at various time intervals in a storm = slope of the curve.
- It’s a graph of cumulative rainfall against time (after it’s been arranged in chronological order). Rainfall is measured in terms of mass-curve by float type and weighing type rain gauges, but exclusively in terms of depth by symon type rain gauges.
Preparation of Mass Curve
- It is prepared for recording type raingauges.
- It can be prepared for non-recording raingauges also.
- For non-recording raingauges, mass curves are prepared from knowledge of the approximate beginning and end of a storm and by using the mass curves of adjacent recording gauge stations as a guide.
To prepare the mass-curve, the rainfall data obtained by non-recording type rain gauge is processed (i.e. in the form of cumulative w.r.t. time). The following information about the rainfall at a specific location can be extracted using mass curves.
1. It furnishes the information on duration of occurring rainfall and its Magnitude.
2. It provides the information on starting and end times of the given rainfall.
3. Of a given storm, it enables to determine the rainfall intensity at different time intervals. The intensity of rainfall is the slope of mass curve. A mass curve is shown in figure
