CS(AR)-22/98-99 : Precipitation network design for Myntdu-Leska basin

Abstract

Precipitation is the most basic data required for any water resources studies. Estimation of the number and location of the rain gauge stations which will provide sufficient information regarding rainfall falling over the catchment is referred as network design. A rain gauge network is intended to serve the general as well as specific purposes such as water supply, hydro power generation, flood forecasting, irrigation and flood control etc.

In the present study, the network design for the Myntdu basin has been carried out. The basin lies in the zone of highest rainfall in the world (Cherapunjee is about 50 km from Myntdu).The rains are of long duration and occur mostly between March and October. During March and April the rainfall is sporadic, but it is steady and heavy or very heavy during May to October. Annual rainfall in the basin is over 10,000 mm. There is wide spatial variation in this small but almost all hilly catchment. The rainfall data of seven existing raingauge station in and around the study area have been analysed using various methods which take into account the location and type of basin and its climate. precipitation characteristics from the existing rainguage stations etc. Apart from BIS recommendations, Cv method, Key station method and spatial correlation method have been tried. Based on the study, the accuracy of the existing network in estimating the average areal rainfall is not within the prescribed limits. To bring the accuracy within the reasonable limit, additional four raingauge stations have been proposed in the catchment with their possible locations.