Holly Richter

• Doctor of Philosophy
• Principal at Resilient Rivers LLC

Groundwater is the most ubiquitous source of liquid freshwater globally, yet its role in supporting diverse ecosystems is rarely acknowledged1,2. However, the location and extent of groundwater-dependent ecosystems (GDEs) are unknown in many geographies, and protection measures are lacking1,3. Here, we map GDEs at high-resolution (roughly 30 m) and...

Groundwater is the most ubiquitous source of liquid freshwater globally, yet its role in supporting diverse ecosystems is rarely acknowledged1,2. However, the location and extent of groundwater-dependent ecosystems (GDEs) are unknown in many geographies, and protection measures are lacking1,3. Here, we map GDEs at high-resolution (roughly 30 m) and...

Freshwater connectivity and the associated flow regime are critical components of the health of freshwater ecosystems. When freshwater ecosystems are fragmented, the movements and flows of species, nutrients, sediments, and water are altered, changing the natural dynamics of freshwater ecosystems. The consequences of these changes include declines...

Groundwater is a critical resource not only for human communities but also for many terrestrial, riparian, and aquatic ecosystems and species. Yet groundwater planning and management decisions frequently ignore or inadequately address the needs of these natural systems. As a consequence, ecosystems dependent on groundwater have been threatened, deg...

The San Pedro River originates in Sonora, Mexico, and flows north through Arizona, USA, to its confluence with the Gila River. The 92-km Upper San Pedro River is characterized by interrupted perennial flow, and serves as a vital wildlife corridor through this semiarid to arid region. Over the past century, groundwater pumping in this bi-national ba...

Groundwater pumping along portions of the binational San Pedro River has depleted aquifer storage that supports baseflow in the San Pedro River. A consortium of 23 agencies, business interests, and non-governmental organizations pooled their collective resources to develop the scientific understanding and technical tools required to optimize the ma...

Due to water limitation, thresholds in hydrologic and biogeochemical processes are common in arid and semi-arid systems. Some of these thresholds such as those focused on rainfall runoff relationships have been well studied. However to gain a full picture of the role that thresholds play in driving the hydrology and biogeochemistry of xeric systems...

Wet/dry mapping provides a low-cost, comprehensive snapshot for monitoring flow conditions in rivers with interrupted perennial (spatially intermittent) surface flow. When used in conjunction with more traditional point-specific stream flow or groundwater measurements, it provides a better understanding of hydrologic systems at the broad landscape...

Spatial data sets to assess the nature of stream groundwater interactions and the resulting power law/fractal structure of travel time distributions are rare. Spatial data sets can be collected using high technology or by use of a large number of field assistants. The labor intensive way is expensive unless the public can be enlisted as citizen sci...

The Monsoon'90 Experiment conducted at the USDA-ARS Walnut Gulch Experimental Watershed in southeast Arizona was the start of a long arc of subsequent experiments and research that were larger, longer-term, more international, more interdisciplinary, and led to more direct integration of science for decision making and watershed management. In this...

The San Pedro Basin sits within an intermountain ecotone with the Sonoran and Chihuahuan Deserts to the west and east and the Rocky Mountain and Sierra Madre Mountain habitats to the north and south. The headwaters of the basin originate in northern Sonora and flow north into southeast Arizona. As the region's only remaining perennial stream, the S...

The San Pedro River originates in northern Sonora near the town of Cananea and spans the U.S. - Mexico border into southeastern Arizona. The San Pedro Basin and perennial portions of its river support one of the most ecological diverse regions in the world. The regional groundwater aquifer which largely supports perennial flow and the associated ri...

The Upper San Pedro Partnership (USPP) (http://www.usppartnership.com/) has been in existence since 1998. Its purpose is to coordinate and cooperate in the implementation of comprehensive policies and projects to meet the long-term water needs of residents within the U.S. side of the basin and of the San Pedro Riparian National Conservation Area. T...

Water resources management in Arizona is critical to the development and sustainability of local communities. Several regions in the state are facing immediate challenges to meet water demands. However, tools to assist the wide range of water interests understand the impact of decisions are lacking. This paper describes the development of a dynamic...

Successful binational planning and management of water resources is a complex process dependent on informed decision-making across diverse economic, social and political sectors. Additional technical and scientific information is often required as a part of this process. A critical factor in this process is how effectively social and physical scien...

A primary goal of the HELP (Hydrology for the Environment, Life, and Policy) Program is the integration of science with policy and decision makers. This presentation will provide an overview of the HELP Program and our experience with the evolution of natural resources research in the San Pedro Basin into a mature example of integrated science and...

The composition and structure of native riverine ecosystems are tightly linked to natural hydrologic variability. By managing river flows for water supplies and power generation, water management agencies have inadvertently caused considerable degradation of riverine ecosystems and associated biodiversity. New approaches for meeting human needs for...

Approaches to conservation and natural resource management are maturing rapidly in response to changing perceptions of biodiversity and ecological systems. In past decades, biodiversity was viewed largely in terms of species richness, and the ecosystems supporting them were seen as static adn predictable(Fielder et.al. 1997). Conservation activitie...

Thesis (Ph. D.)--Colorado State University, 1999. Includes bibliographical references.

1. OBJECTIVES Understanding how anthropogenic and climate-induced changes alter ecological systems and evaluating the effects of alternative hydrologic profiles on these ecosystems are important concerns in the semi-arid West. The goal of the proposed research is to incorporate hydrologic, vegetation, avian, and economic models into an integrated f...