Reservoir Capacity and Yield

Reservoir Capacity and Yield CAPACITY CURVETopographic map(with contours at 0.5-1m spacing)Dam catchment areaDam site and dam layout

HOW TO PRODUCE A CAPACITY CURVE

METHODS OF PRODUCING THE CAPACITY CURVEEnd areas methodTrapezoidal Prismoidal

END AREAS METHOD FOR CALCULATING THE VOLUMES.

Contour (m)Elevation difference(m)Area (m2)Volume (m3)Cum. Volume (m3)1195.4000011960.637774.9111332.47311332.47311971232018.04134896.475146228.94811981411241.07321629.555456526.0311991606791.35509016.21830645.76512001915268.41761029.881270046.09DRAW THE CAPACITY CURVERESERVOIR SIZINGDetermine active storage capacity using Ripple diagram or the mass diagram. Plot with time as abscissa and cumulative inflow as ordinate. For constant release Rt, line with slope Rt placed tangential. Maximum distance between the two gives ACTIVE STORAGEMASS CURVE ANALYSIS

Estimating Active Storage Capacity

Mass Balance Equation of Reservoirs St-1 + Qt Rt Lt = StWhere St-1 is storage at end of previous time interval St is storage at end of current time interval Qt is inflows at current time interval Rt is release at current time interval Lt is loss (evap/seepage) at current time interval

Reservoirs have a fixed storage capacity, K, so

St