Spatial analysis of borrow pits along the Platte River in south-central Nebraska, USA, in 1957 and 2016

Abstract

The Central Platte River Valley (CPRV) of Nebraska provides critical habitat for wildlife, while serving agricultural, industrial, and other human uses. Mining of sand and gravel from the floodplain of the Platte River has supported construction of roads and other uses, and this extraction has created many borrow-pit ponds, lakes, and other small bodies of standing water (hereafter borrow-pits), further transforming riparian and prairie habitats. The objective of this study was to compare the abundance, size, and distribution of borrow pits before construction of Interstate 80 (1957) and at present (2016) from Lexington to Chapman, Nebraska, a length of river spanning about 146 km (90 mi) and sometimes referred to as the Big Bend Reach. Orthorectified aerial imagery of the Platte River was obtained for years 1957 and 2016, and we digitized the standing bodies of water within the floodplain in Arc-GIS. Total numbers of borrow pits and measures of pit shape were calculated and compared between floodplain regions where imagery overlapped. From 1957 to 2016, the number of borrow pits increased from 300 to 786, total area occupied by pits expanded by 538%, and total shoreline of pits increased by 261%. In 2016, aerial imagery was available for a larger extent of the floodplain and contained a total of 1,062 borrow pits covering 16 km 2 (6 mi 2), with a total shoreline of 581 km (361 mi). For context, the Platte River channels' approximate area was 45 km 2 (17 mi 2) and shoreline 1,582 km (983 mi) between Lexington and Chapman, Nebraska, in 2016. Results provide insight into historical and current presence, distribution, and shape of borrow pits along the Platte River, as well as serve as a reference point for future studies investigating regional landscape change and ecological effects of creating hundreds of borrow pits on the floodplain.

Assessing the hydroregime of an archetypal riverine wet meadow in the central Great Plains using time‐lapse imagery

“…Wet meadows have been reduced in the CPRV to 5% of their historic area (Currier et al 1985, Sidle et al 1989. A myriad of hydrologic, climatic, and anthropic changes (Johnson et al 2012, Fassnacht et al 2018, Pauley et al 2018, Caven et al 2019b) have resulted in encroachment of woody vegetation and channel incisions that threaten to lower the shallow groundwater table (Williams 1978, Currier 1982, Eschner et al 1983, Randle and Samad 2003. In turn, this has resulted in the drying of some wet meadow systems, causing a change in stable state to lowland prairie ecosystems, thus rendering the previous wet meadows drier and more viable for agricultural row-crop conversion (Sidle and Faanes 1997).…”