Arrangement and structure ofweirs on the Kalampangan canal

Abstract

The main objectives of this study were to determine the suitable arrangement and structure of weirs on the Kalampangan Canal in the Mega Rice Project (MRP) area of Central Kalimantan based on the field investigation and laboratory test of materials. The purpose of the weir construction in this area is to keep the water level of canals high and to prevent the outflow of groundwater from peatlands. The field investigation was carried out to identify the types and reasons of the damages on the weirs which were already constructed on the canal. The undisturbed peat samples carefully taken by using the thin-wall sampler were used to determine the physical parameters of the peat. The sampling rates of peat columns were more than 90 %. The unconfined compressive strength of peat in this site was 3,2 kN/m2. The weir should be strong mechanically and hydrologically during dry and wet seasons. The weir has a spillway of which the overflow width and depth are 10 m and 0.3 m respectively. The slope of the embankment is 2:1 with wooden supports. The weir structure is divided into two zones, a water blockade zone and an erosion protection zone. The clay soil is used for the water blockade zone and the sand bags are used for the erosion protection zone. The erosion protection zone can prevent the destruction by permeation of water. Clay and sandy soils can be procured locally.