Mass inflow is a curve which represents the cumulative flow in a reservoir at any particular instance.
It is a plot between cumulative inflow in the reservoir with time.
It can be prepared with the help of a hydrograph of the river for the dam site for a large number of years.
We know hydrograph is a plot or curve between discharge versus time.
Figure 9.4 (a) shows a hydrograph of a river for the dam site for a number of years and Fig. 9.4 (b) a corresponding mass curve prepared from the hydrograph of Fig. 9.4 (a). Let starting year of the hydrograph is 1998.
The total quantity of water that has flown through the river from 1998 to a time t1 (say 2001) has been represented by the hatched area.
In mass curve, the corresponding ordinate at time t1 (ordinate AB) will represent the total volume of water indicated by the hatched area of hydrograph curve.
Similarly the ordinates of the mass curve corresponding to other years can be determined from the hydrograph curve and plotted.
When all such points are joined free hand we get the mass curve corresponding to the hydrograph.
It is evident that a mass curve will continuously rise as it is the plot of accumulated inflow versus time.
Periods of no inflow would be indicated by horizontal lines on the mass curve.
The slope of the mass curve at any time gives the rate of inflow at that time.
Mass inflow curve is sometimes known as Ripple diagram also.
SOME IMPORTANT TERMS Following are some important terms which are frequently use in the exploitation of ground water reservoir. 1. Aquifer. The permeable formations which permit appreciable water to move through them under ordinary field conditions are know as aquifers. These are geological formations made of gravel or sand, which possess lot of ground water….
ROLLING GATE This grate is show in Fig. 14.24. It consists of a steel cylinder as large in diameter as the height of the opening and spanning between the piers. Each pier has an inclined rack. The gate is wound around the periphery of the cylinder. The gate is also attach to the incline rack…
Sprinkler Irrigation Sprinkling irrigation is the method of applying water to the soil surface in the form of a spray which is somewhat similar to rain. In Sprinkling irrigation method, water is sprayed into the air and allowed to fall on the soil surface in a uniform pattern at a rate less than the infiltration…
INTRODUCTION A structure whose main purpose is to supply water to the off taking canal is know as head works. When the off taking canal is to supply water for irrigation purpose, its headworks is call irrigation head works. Irrigation headworks may be divid into two categories. 1. Diversion headworks or simply head works. 2….
ESSENTIAL PROPERTIES OF A GOOD LINING Following are the essential properties of a good lining: The lining should be completely water tight. The rugosity coefficient of the lining material should be low, so as to make the section more efficient, hydraulically. The lining should be strong and durable. Initial cost of lining and its subsequent…
SIDE CHANNEL SPILLWAY This spillway is suitable for earth or rock fill dams, in narrow canyons and other situations. This spillway is also the best choice where a long overflow crest is require so as to limit the surcharge head and also under the situation where abutments are steep and precipitous. In this spillway the…