| Title: | Impact of coastal wetland restoration plan on the water balance components of Heeia Watershed, Hawaii |
| Authors: | Ghazal, K.A., O.T. Leta, A.I. El-Kadi and H. Dulai |
| Year: | 2020 |
| Journal: | Hydrology |
| Volume (Issue): | 7(4) |
| Pages: | |
| Article ID: | 86 |
| DOI: | 10.3390/hydrology7040086 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | wetland effects and/or processes |
| Secondary Application Category: | irrigation impacts or irrigation BMP scenarios |
| Watershed Description: | Heeia River, located on northeast coast of the Island of Oahu in the state of Hawaii, U.S. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Optimal restoration and management of coastal wetland are contingent on reliable assessment
of hydrological processes. In this study, we used the Soil and Water Assessment Tool (SWAT) model to
assess the impacts of a proposed coastal wetland restoration plan on the water balance components of
the Heeia watershed (Hawaii). There is a need to optimize between water needs for taro cultivation
and accompanying cultural practices, wetland ecosystem services, and streamflow that feeds downstream
coastal fishponds and reefs of the Heeia watershed. For this, we completed two land use change scenarios
(conversion of an existing California grassland to a proposed taro field and mangroves to a pond in
the wetland area) with several irrigation water diversion scenarios at different percent of minimum
streamflow values in the reach. The irrigation water diversion scenarios aimed at achieving sustainable
growth of the taro crop without compromising streamflow value, which plays a vital role in the health
of a downstream fishpond and coastal environment of the watershed. Findings generally suggest that
the conversion of a California grassland to a patched taro field is expected to decrease the baseflow
value, which was a major source of streamflow for the study area, due to soil layer compaction,
and thus decrease in groundwater recharge from the taro field. However, various taro irrigation water
application and management scenarios suggested that diverting 50% of the minimum streamflow value
for taro field would provide sustainable growth of taro crop without compromising streamflow value
and environmental health of the coastal wetland and downstream fishponds. |
| Language: | English |
| Keywords: | Hawaii; Heeia; SWAT; water balance components; wetland restoration |