The Modelling of Groundwater Table Management for Canal Blocking Scenarios In Sub Peatland Hydrological Unit

Abstract

Drainage in peatland caused reducing water storage and subsidence. Groundwater
level fluctuations are a major role in the water balance that occurs in peatlands. The
research was conducted in a specific area of agricultural peatland. The location in
Sub-Peatland Hydrological Unit (Sub- PHU) 5 and 6 Kahayan Sebangau, Central
Kalimantan Province, Indonesia. Modeling for groundwater table was applied using
Freewat / Modflow software with input rainfall probability 80% (R80), infiltration,
and evapotranspiration data analysis. Groundwater table should not be less than
minus 0.4 meters based on the Indonesian Ministry of Environment and Forestry
(Menlhk). The deficit means the groundwater level below -0.4 m and surplus upon
the criteria. Land modeling is simulated with an area of 300 x 1000 meters. The
calibration in the model was found conductivity values, 50 m / day or 5.78 x 10-4 m /
s with the best value with the largest NSE and Correlation. The modeling showed
that the deficit occurred in seven months. The groundwater management is how to
keep the water level upon -0.4 m with the planning of canal blocking height. The
scenarios are 0.2 m. 0.3 m, 0.4m, and 0.5 m upon the base flow of the canal. The
best scenario was chosen 0.5m according to the simulation which has the water
level upon -0.4 m.