Hydrological parametrization of peatland water level dynamics using
satellite-based precipitation: a case study in Brunei
Abstract
Tropical peatlands are characterized by highly organic, heterogeneous,
and compressible peat soils. Without sampling and disturbing the soil,
peat hydraulic and discharge parameters can be estimated from analyzing
the in situ water level rise and recession. Such an analysis allows for
the representation of the hydraulic behavior of a peatland from water
level, precipitation, and topography data. Water level is measured in
several remote tropical peatlands, whereas in situ precipitation is
often not. Gridded satellite precipitation products provide an
alternative, but are coarse and highly uncertain. Here, we introduce an
algorithm for the hydrological parameterization of water level dynamics
using satellite-based precipitation, and apply it to a tropical peatland
in Brunei, while accounting for representativeness errors in the
precipitation data. First, we adapt the rise and recession analysis
developed by Cobb & Harvey (2019) for use with Integrated
Multi-satellitE Retrievals for the Global Precipitation Measurement
mission (IMERG) precipitation estimates. The adapted rise analysis
reduces the average error in the slope of the master rise curve with
IMERG data from 21% to 3%. The average daily recession overestimation
with IMERG data is reduced from 0.45 cm day -1 to 0.18
cm day -1. We also quantify the sensitivity of our
rise analysis to precipitation errors using an ensemble of erroneous
precipitation time series. Second, the adapted master rise and recession
curves are used to fit soil hydraulic and discharge function parameters
within the peatland-specific module of the NASA Catchment Land Surface
Model. Our method enables the retrieval of accurate hydrological
parameters for our case study, and should be tested in other peatland
regions and with other satellite-based precipitation products.