Irrigation (121-140)

Updated: Apr 25, 2020

121. The aqueduct or superpassage type of works are generally used when

high flood drainage discharge is large and continues for a long time

122. An aggrading river is a silting river

123. Tortuosity of a meandering river is the ratio of curved length along the channel to the direct axial length of the river reach

124. The meander pattern of a river is developed by dominant discharge


125. The main cause of meandering is the extra turbulence generated by the

excess of river sediment during floods

126. Tortuosity of a meandering river is always greater than l

127. A meander increases the river length but a cut off reduces the river length

128. River training for depth is achieved by groynes and bandalling

129. Main purpose of mean water training for rivers is to preserve the channel in good shape by efficient disposal of suspended and bed load

130. If D is the depth of scour below original bed, then the width of launching apron is generally taken as 1.5 D

131 1) Levees are constructed parallel to river flow,

2) Spurs are constructed transverse to river flow.

132. A repelling groyne is aligned pointing upstream

133. A river training work is generally required when the river is meandering type

134. Length and width of a meander are pro portional to (discharge)¹/²

135. A river bend in alluvial soil is characterized by scouring on concave side and silting on convex side

136

a) Intensive irrigation should be avoided in areas susceptible to water logging.

b) Extensive irrigation should be adopted in areas susceptible to water logging

137. A land is known as waterlogged capillary fringe reaches the root zone of plants

138. Lining of irrigation channels decreases the waterlogging area

139. A runoff river plant is a low head scheme

140. The net speed under which the turbine reaches its peak efficiency is called

design speed

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