Water Resources Research Act Program

Details for Project ID 2020GU272B

A sustainable plan for stormwater management and flooding at Garapan, Saipan

Institute: Guam
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $29,947 Total Non-Federal Funds: Not available

Principal Investigators: Dr. Myeong-Ho Yeo

Project Summary: Flooding is an overflow of a large amount of water beyond its normal limits. Floods are the most common and widespread of all weather-related natural disasters. Floods in the U.S. kill more people each year than other natural disasters. Average annual flood damages in the U.S. are more than 2.2 billion dollars a year. Furthermore, increasing trends in number of these natural disaster have been observed. Today flooding control including stormwater management has become a critical issue in civil and environmental engineering applications. There are several different kinds of flood, and each one bears a different impact in terms of how it occurs, the damage it causes, and how it is forecasted. A coastal flood occurs in areas the lie on the coast of ocean. Of particular storm surge, which high winds push water to onshore, is the leading cause of coastal flooding and often the greatest threat associated with a tropical storm. As the most dangerous kind of floods, flash flood occurs when excessive or heavy rainfall in a short time fills river beds. It is characterized by an intense, high velocity torrent of water. A surface flood occurs when moderate precipitation accumulates over several days, intense precipitation falls over a short period, or a river overflows because of an ice or debris jam or dam or levee failure. It is therefore essential to understand a major flood type and its characteristics at an interest site for protecting public health, safety, infrastructure, and properties.Stormwater management is originally intended for flood control and minimal water quality improvement. With stormwater runoff, four major problems begin to emerge;•Flooding: excess stormwater increases the extent, severity, and frequency of floods.•Degraded water quality: stormwater carries a number of pollutants, nutrients, pathogens, and floating matters on streets.•Erosion: increased stream volume and velocity exacerbate streambank erosion.•Sewer overflows: increasing stormwater volumes contribute to combined sewer overflows. Floods are a common occurrence in the lower Garapan area, Saipan. The relatively flat terrain in the target area causes lack of gradient, which prevents adequate drainage and the lack of drainage outlets. Thus, severe ponding problems are emerged from following moderate and heavy rainfalls. A flood prone zone includes an extensive number of residential structures, stores, and commercial establishments. Especially, the most critical area is located between the hotel resort area and the West Coast Highway. Due to frequent flooding over the area, it can be expected that the following offshore water quality, which caused by erosion and sewer overflows, and flooding damages. The objectives of the proposed project can be summarized as the followings;1)To collect relevant base data, maps, aerial imagery;2)To identify stormwater runoff flowing characteristics;3)To develop stormwater management model;4)To suggest the Low Impact Development (LID);5)To simulate the stormwater model for current and future weather conditions.