HorsleyWittenGroup2017 Horsley Witten Group , Inc. and Malcolm Johnson Talakhaya Watershed Soil Loss Assessment: Phase II Stream Monitoring Report NOAA Coral Reef Conservation Program. NOAA NOS Office of Coastal Management 2017 FY17; CRCP Project ID: 30010; Project Title: Continuation of Talakhaya Soil Loss Assessment https://www.ncei.noaa.gov/data/oceans/coris/library/NOAA/CRCP/NOS/OCM/Projects/30010/HorsleyWittenGroup2017_Talakhaya_Soil_Loss_PhaseII_Cover.pdf Tech Report https://www.ncei.noaa.gov/data/oceans/coris/library/NOAA/CRCP/NOS/OCM/Projects/30010/HorsleyWittenGroup2017_Talakhaya_Soil_Loss_PhaseII.pdf "The purpose of this report is to provide a comprehensive summary of results from a two-phase, stream monitoring study of soil loss in the Talakhaya Watershed on Rota, CNMI between 2012 and 2017. This NOAA-supported study was conducted to assess and to quantify the change in soil loss from Talakhaya badlands in conjunction with revegetation efforts led by Rota DLNRForestry staff that started in 2007. Phase I of the monitoring study was conducted by the University of Guam (UOG) between 2012 and 2014. This study attempted to measure localized precipitation, establish stream stage-discharge relationships, and quantify turbidity and total suspended solids at fixed monitoring stations in four streams. The monitored streams were strategically selected to represent subwatersheds with varying levels of vegetated cover, including a mostly forested subwatershed, two areas where revegetation efforts had occurred or were underway, and a control subwatershed that included eroding badlands. UOG researchers concluded that reductions in soil loss were observed, with the caveat that the differences between unvegetated and revegetated streams were not significant. Further, they suggest that more time was needed for plants to establish (Golabi and Manibusan, 2014) and that additional monitoring was required to quantify the information with statistical certainty. There was a fifteen month gap in stream monitoring, during which time revegetation efforts continued. Monitoring was resumed in 2016-2017 by NOAA Coral Fellows. Phase II monitoring protocols were based on the methodology used in Phase I, but were adapted to account for progress in the revegetation efforts. Specifically, a new control subwatershed (barren areas) was added since DLNR revegetation efforts had expanded into the original control subwatershed from Phase I. Unfortunately, lack of rain and flowing streams, as well as staffing and equipment issues during Phase II, limited the number of additional water quality samples and flow data collected. Talakhaya is frequently referenced as an example where empirical monitoring data have shown improvement in water quality due to watershed restoration efforts. Based on an analysis of Phase I and Phase II results, however, this conclusion should not be made with any certainty due to a number of limitations (e.g., few number of samples, equipment issues, lack of information on the extent of vegetative cover or other sediment sources in each subwatershed). Comparing water quality across subwatersheds or trends in improvement over time based on stream monitoring, particularly in remote mountainous island watersheds, is challenging. Estimating reductions in sediment loss, or even showing relative improvement in the revegetated watersheds over time, is not feasible with existing data. However, the lack of stream data support should not diminish the anticipated benefit of the revegetation effort or dampen enthusiasm over this herculean effort. While few definitive conclusions can be drawn directly from the stream monitoring data to date, a number of recommendations for improving and expanding future monitoring in the watershed and redefining more obtainable project goals and objectives are provided. In addition, recommendations are provided for utilizing other metrics to measure revegetation performance." 20170831000000 CNMI Guam 146 142 12.732335 21 techreport techreport publication CoRIS Bibliographic