Title: | An improved SWAT vegetation growth module and its evaluation for four tropical ecosystems |
Authors: | Alemayehu, T., A. van Griensven, B.T. Woldegiorgis and W. Bauwens |
Year: | 2017 |
Journal: | Hydrology and Earth System Sciences |
Volume (Issue): | 21(9) |
Pages: | 4449–4467 |
Article ID: | |
DOI: | 10.5194/hess-21-4449-2017 |
URL (non-DOI journals): | |
Model: | SWAT-T & SWAT |
Broad Application Category: | hydrologic only |
Primary Application Category: | crop, forest and/or vegetation growth/yield and/or parameters |
Secondary Application Category: | model and/or data comparison |
Watershed Description: | 13,750 km^2 Mara River, which drains portions of southwest Kenya and northeast Tanzania before flowing into Lake Victoria. |
Calibration Summary: | |
Validation Summary: | |
General Comments: | |
Abstract: | The Soil and Water Assessment Tool (SWAT) is
a globally applied river basin ecohydrological model used in
a wide spectrum of studies, ranging from land use change
and climate change impacts studies to research for the development
of the best water management practices. However,
SWAT has limitations in simulating the seasonal growth cycles
for trees and perennial vegetation in the tropics, where
rainfall rather than temperature is the dominant plant growth
controlling factor. Our goal is to improve the vegetation
growth module of SWAT for simulating the vegetation variables
– such as the leaf area index (LAI) – for tropical ecosystems.
Therefore, we present a modified SWAT version for
the tropics (SWAT-T) that uses a straightforward but robust
soil moisture index (SMI) – a quotient of rainfall (P) and
reference evapotranspiration (ETr) – to dynamically initiate
a new growth cycle within a predefined period. Our results
for the Mara Basin (Kenya/Tanzania) show that the SWAT-T simulated
LAI corresponds well with the Moderate Resolution
Imaging Spectroradiometer (MODIS) LAI for evergreen
forest, savanna grassland and shrubland. This indicates that
the SMI is reliable for triggering a new annual growth cycle.
The water balance components (evapotranspiration and
streamflow) simulated by the SWAT-T exhibit a good agreement
with remote-sensing-based evapotranspiration (ET-RS)
and observed streamflow. The SWAT-T model, with the proposed
vegetation growth module for tropical ecosystems, can
be a robust tool for simulating the vegetation growth dynamics
in hydrologic models in tropical regions. |
Language: | English |
Keywords: | |