LRGV_SOW_1.pdf

TITLE: Geomorphic change detection along the U.S.-Mexico border in south Texas, within the Lower Rio Grande Valley (LRGV).

Objective: Geomorphic change detection from airborne lidar datasets acquired in 2010 and 2023 along the U.S.-Mexico border in south Texas, within the Lower Rio Grande Valley (LRGV).

Statement of Problem: The SBSC is working with the Wetland and Aquatic Research Center

(WARC) and Ecosystems Mission Area (EMA), U.S. Fish and Wildlife Service and the U.S.

Customs and Border Protection on landscape conservation projects related to the international border wall along the U.S.-Mexico border in south Texas, within the Lower Rio Grande Valley

(LRGV). The Lower Rio Grande National Wildlife Refuge (LRGVNWR) was established in

1979 with a management priority to protect the unique biodiversity of the LRGV. As a wildlife corridor, the refuge follows the Rio Grande along the last 275 river miles. It connects isolated tracts of land managed by private landowners, non-profit organizations, the State of Texas, and two other USFWS National Wildlife Refuges: Santa Ana and Laguna Atascosa. Water is a critical resource for wildlife in this semi-arid region, and many of the LRGVNWR tracts are located near the river adjacent to water and wetland resources critical to wildlife.

In recent years, border wall construction activities on the LRGVNWR river tracts have increased. Beyond just the building of fences and walls, border wall construction has cleared vegetation and altered roads, levees, and lighting infrastructure. There is concern that these changes in the landscape have affected the geomorphology of the environment in ways that may impact the movement of water, sediment, and wildlife. In particular, there is concern that topographic changes have created barriers to water flow, altered flooding patterns, altered the flow of water from the floodplain to the river channel, or degraded the floodplain and river channel in other ways which may create increased risks to wildlife. However, these geomorphic changes have been unstudied with respect to the recent border wall construction activities and the river. WARC contracted the acquisition of airborne lidar data in the LRGV in 2023.

Scope: This project will analyze 2023 aerial lidar data (to be provided by project PIs) with respect to a comparable airborne lidar dataset that was acquired in 2010 (TetraTech/Watershed

Sciences, Inc. for the International Boundary and Water Commission (IBWC)) in order to quantify geomorphic changes along the border wall and river in the LRGV. Geomorphic change detection will be conducted to determine if border wall construction, and flow paths near the border wall may impact wildlife migration.

WORK REQUIREMENTS

Contractor must have prior experience conducting geomorphic change detection analyses, using aerial or ground-based lidar data. Experience must be demonstrated in prior publications/reports that must be made available to the project PIs.

Contractor must have experience collecting geomorphic data within the Lower Rio Grande

Valley, such that they are familiar with data collection requirements along an international border.

Methodology:

1. Conduct change detection of airborne lidar datasets acquired in 2010 and 2023 along the

U.S.-Mexico border in south Texas, within the Lower Rio Grande Valley (LRGV).

2. Interpret geomorphic changes from the lidar topographic change detection results along the international border wall and Rio Grande River within LRGV.

3. Assess uncertainty and errors associated with change detection methods as outlined in items 1 and 2.

4. Acquire additional geomorphic data and/or field measurements to validate and verify the topographic change detection results and geomorphic change detection interpretations if needed.