STREAM FLOW MONITORING FOR WATERSHED STUDIES FOLLOWING ‘RE-VEGETATION’ FOR REDUCING THE

SEDIMENT LOADING ON THE SHORELINES OF MICRONESIAN ISLAND OF ROTA, CNMI

Mohammad H. Golabi, Soil ScientistSydonia Manibusan, Research Associate

College of Natural and Applied SciencesUniversity of Guam

Presented at the 71st Annual SWCSLouisville, KN

Where is Rota (CNMI)?

CNMI Marshall IslandsGuam

YapPalau ChuukPohnpei

Kosrae

Google Earth image

Micronesia

A bird eye view of Rota

Some of the beautiful shores of Rota that might be already polluted by sedimentation

Talakhaya Watershed overview

Typical exposed/badland areas at the Talakhaya Watershed in Rota, CNMI

Rota

volcanic area

Google Earth image

Streams/Rivers that drain the Talakhaya Watershed runoff to ocean

Purpose of the Project Talakhaya watershed was

identified as a priority area to improve water quality and reduce sedimentation impacting coral reefs.

The study was designed to quantify the reduction in sediment as a result of the re-vegetation efforts occurring in Talakhaya Watershed.

Some of the management practices:

(i.e. Vetiver grass establishment)

Volunteer workers carrying Vetiver grass seedlings to Talakhaya Watershed

Areas where Vetiver grass is being planted at the Talakhaya Watershed in Rota

Marching towards Re-Vegetation

Volunteer workers carrying Vetiver grass seedlings to Talakhaya Watershed (at break)

Picture time

Volunteers at work planting Vetiver grass

seedlings_____________________

Vetiver seedlings are mass produced and prepared at the Rota’s DLNR in Rota.

Seedlings and equipment are carried manually to the selected areas of the Talakhaya Watershed despite steep slopes and rough terrain leading to the designated sites

Seedlings are planted one by one

Talakhaya on-going re-vegetation project(Dr. Golabi helping a Rota DLNR manager with planting of the Vetiver)

Show Time

Some of the results from the re-vegetation efforts so far:

Remember This:

More Show time: Only 4 months old Vetiver

What do you think?

Proud members of the team standing in the areas where Vetiver grass planting is completed

Victory moments

Areas where Vetiver grass is planted which in turn has induced improvement with vegetation growth

Year old Vetiver grass at the Talakhaya Re-vegetation project site:

Note: As shown Vetiver works as barrier to sediment loading down to the streams and shorelines, hence protecting the precious coral from siltation.

Project GoalsYear 1

Site assessment of the watershed

Obtain permissions and collaborate with community members and local agencies

Purchase equipment needed

Install equipment

Begin sampling/monitoring

Year 2

Continue Planting/Monitoring

Analyze Data

Submission of Final Report

Presentation of Findings to the community and resource agencies

Monitoring Methodology/Tools

Hydrologic Data Collection Rainfall Stream Level Water Quality Stream Discharge → →

Soil Sampling tools:

↓

Methodology/Observations

Rain Gauge

Water Quality Meter

Level Logger Flow Meter Analysis of Beach sediment/deposits

Soil sampling at the Talakhaya re-vegetation site for analysis

Soil Sampling (Cont’d)

Stream Study Sites

Treatment categorization at the Talakhaya Watershed Site

_________________________

Unvegetated Project Stream (TK1)

Re-vegetated Project Stream (TK2 and TK3)

Natural Vegetation Control Stream (TK4)

Stream Monitoring Results:

Stream Comparison

y = ‐3857.4x2 + 706.31x + 43.938 R² = 0.14785

y = 5693x2 ‐ 805.15x + 49.887 R² = 0.17939

y = 233.45x2 + 195.54x + 36.56 R² = 0.11453

y = 2161.5x2 ‐ 114.04x + 35.472 R² = 0.58621

0.0

50.0

100.0

150.0

200.0

250.0

0.0001 0.001 0.01 0.1 1

Turbidity

(NTU

)

Average Rainfall (in)

Talakhaya 6‐Hour Average Rainfall vs Turbidity

TK4

TK3

TK2

TK1

Poly. (TK4)

Poly. (TK3)

Poly. (TK2)

Poly. (TK1)

Stream Comparison

Educational efforts at the local level in Rota

Educational efforts at the local level (cont’d)

Recommendations:

It appears that re-vegetation to include Vetiver grass has had a positive impact on reducing sedimentation, however:

New growth must have time to establish itself

More data is required

Need for increased community awareness

More about Vetiver and its effect on Sedimentation Mitigation

Pago Bay construction site before a big rain

Source: Jason Biggs

Pago Bay construction site after a big rain

Source: Jason Biggs

Seedling development

Growing stage at Pago Bay cont’d

Since the Vetiver grass is salt tolerance it can also grow very close to sea water and protect the shoreline on the spot (Pago Bay, Guam)

Cutting at hip height

Cutting at hip height cont’d

Our Vetiver grass inventory in UOG research station in Ija (six years after planting)

We also have fun after we finish our daily work in Rota, etc.

Flying Residents of Rota

Rota’s ….bird

Rota’s ………........ Birds

Acknowledgement This project was funded by NOAA's Coral Reef

Conservation Program through National Fish and Wildlife Foundation.

Dr. Dana Okano from NOAA office in Saipan, CNMI

Staff from the DLNR, Forestry Division in Rota.

Xerxes Camacho, Research Assistant, Rota

Clancy Iyekar, Soil Labs, UOG

Our calabash cousins: all WERI and Marine Lab folks and of course the POETers.

Thank You!

Questions?