Water Resources Research Act Program

Principal Investigators: Shahram Khosrowpanah, Leroy Heitz

Abstract: The Nanpil Watershed is situated in the Sokehs and Nett Municipalities on the Northern side of Pohnpei Island. It is unique in many aspects. This area of approximately 3 square miles provides inflow to the Nanpil River that is the main source of the islands water supply. In recent years large areas of native forests and ecologically sensitive areas are being cleared for housing and road development projects and unmanaged agricultural activities (e.g., sakau/kava plots). These new development activities are now negatively impacting the biodiversity health of much of the area, the headwaters and freshwater resources as well as the mangrove forests and coral reefs of Pohnpei Island. To implement any watershed management/protection plan requires having a better understanding of the physical and environmental components of the watershed. This includes how much rain the watershed receives, how much flow runs through the streams, what is the sediment load in the streams during the year, and how all these dynamic components are related to mans activities within the watershed. The lack of baseline information about the components of watersheds is a critical issue throughout the Federated States of Micronesia. When the political status of the Federated States of Micronesia with the United States changed from Trusteeship into Free Association in 1986, all the stream flow gages that were built and monitored by the US Geological Survey were halted and have remained effectively abandoned. Since 1986 there has been no information on how much flow runs through the streams and how much sediment is being carried to the reefs. The objectives of this project are to: 1) install stream flow, sediment, and raingages for selected sites within the Nanpil Watershed; 2) monitor the gages and develop a rating curve for selected site; 3) develop a correlation between stream flow, sediment load and rainfall; and 4) develop a database for future use. This project will generate baseline information and correlations among the dynamic components of the Nanpil watershed environment. The baseline information will be used for future comparison between Nanpil watershed and the ongoing study for Enipein Watershed. The findings will reveal the impact of the various activities such as land clearing, land sliding/slope failures, and population growth on the quality of the watershed. This information will help various parties such as Conservation Society of Pohnpei (CSP), Land Management, the Pohnpei EPA, and local mayors to implement plans for protecting the watersheds in Pohnpei. Pohnpeis Public Utilities Commission (PUC) will be able to operate the water treatment plan more efficiently by knowing the level of streams turbidity and the available water at the stream. Also the information obtained in this project may be used by Pohnpeis Weather Service to enable them to provide flash flood warnings for Nanpil River.