Darwin Ockerman | Geology Reports

USGS2023

Monitoring sediment transport pathways from an artificial nearshore berm, South Padre Island, Texas, USA, August 2018 to November 2019: Implications for coastal management

During August 2018 – November 2019, the transport pathways of dredge material from a specially constructed nearshore feeder berm were investigated as part of a collaborative study by the City of South Padre Island, U.S. Army Corps of Engineers–Galveston District, U.S. Geological Survey, Partrac GeoMarine Inc., and Texas A&M University, into the efficacy of beneficial use dredge material (BUDM) as a method of replenishing the beach profile and shoreface at South Padre Island, Texas with sediment. Dual-signature (fluorescent and ferrimagnetic) tracer particles, designed to be hydraulically equivalent to the dredge material, were placed on the berm, and a sampling program was initiated to monitor the spatiotemporal movement of tracer particles under the influence of the prevailing hydrodynamic regime. Wave and current data were collected and were used together with available metocean data to identify the forcing mechanisms of sediment transport; improved understanding garnered from the consideration of multiple datasets can be used to inform future coastal management decisions. Tracer analysis results indicated low magnitude, shoreward transport of dredge material from the berm and along shore transport in both northerly and southerly directions. Small amounts of tracer detected in beach face samples demonstrated connectivity between the constructed feeder berm and the shoreface. However, the generally low tracer concentration within beach face samples indicated low rates of sediment transport for berm sediments, and a low magnitude sediment transport pathway from the berm directly to the beach face, with possible storage of sediment in the nearshore bar system. Given that the berm was at or beyond the closure depth and considering the relatively weak prevailing near bottom hydrodynamic conditions, the potential for sediment to be mobilized and transported during the study period was generally low. Periods of higher energy waves, driven by north-northwest winds, were identified as a key driver of sediment transport but due to the infrequent nature of these events the sediment transport regime across the area of interest was temporally limited. Longshore movement of sediment was both north and south, mainly dependent on prevailing wind directions and resulting longshore currents. We discuss implications for coastal zone management and the use of feeder berms as an artificial beach nourishment mechanism to replenish sediments lost by coastal erosional processes. The insight into nearshore emplacement of material can be used by local governments and coastal managers to optimize the efficacy of berm emplacement and implement such schemes as a cost-effective nourishment option, or when onshore placement of material is not feasible.

Texas↗

USGS2019

Report of the River Master of the Delaware River for the period December 1, 2009–November 30, 2010

A Decree of the Supreme Court of the United States, entered June 7, 1954, established the position of Delaware River Master within the U.S. Geological Survey. In addition, the Decree authorizes diversion of water from the Delaware River Basin and requires compensating releases from certain reservoirs, owned by New York City, to be made under the supervision and direction of the River Master. The Decree stipulates that the River Master will furnish reports to the Court, not less frequently than annually. This report is the 57th Annual Report of the River Master of the Delaware River. It covers the 2010 River Master report year, the period from December 1, 2009, to November 30, 2010. During the report year, precipitation in the upper Delaware River Basin was 49.38 inches or 112 percent of the long-term average. Combined storage in Pepacton, Cannonsville, and Neversink Reservoirs remained high much of the year and did not decline below 80 percent of combined capacity until September 2010. A lower basin drought warning was issued by the Delaware River Basin Commission on September 24, 2010. It automatically ended on October 31, 2010, when the reservoir contents rose above drought levels, due in large part to heavy rainfall during the last week of September. River Master operations during the year were conducted as stipulated by the Decree and the Flexible Flow Management Program. Diversions from the Delaware River Basin by New York City and New Jersey were in full compliance with the Decree. Reservoir releases were made as directed by the River Master at rates designed to meet the flow objective for the Delaware River at Montague, New Jersey, on 81 days during the report year. Interim Excess Release Quantity and conservation releases, designed to relieve thermal stress and protect the fishery and aquatic habitat in the tailwaters of the reservoirs, were made during the report year. The quality of water in the Delaware Estuary between Trenton, New Jersey, and Reedy Island Jetty, Delaware, was monitored at various locations. Data on water temperature, specific conductance, dissolved oxygen, and pH were collected continuously by electronic instruments at four sites.

Delaware, Maryland, New Jersey, New York, Pennsylv↗