Journal of Water Resources Planning and Management

Ecosystem services (ES) have complex flow dynamics that operate across distances. However, ES assessments have focused more on their supply. Few studies consider the impacts of interregional flows on ES provision and the spatial and temporal changes of interregional flows are little known. Here, we quantified interregional flows and analyzed their variations by evaluating the interregional dependency of four water-related ES (water yield, flood mitigation, water purification, and soil retention) in the Yellow River Basin, China. The results showed that about one-third of the basin area had $51.3\%–98.9\%$ of the ES sourced from interregional flows, and these areas increased by $2.6\%–11.9\%$ during $2000–2015$. Generally, the upstream regions with contributions of $64.0\%–79.7\%$ of water yield, $93.2\%–96.9\%$ of flood mitigation, $89.0\%–95.3\%$ of water purification, and $53.7\%–97.4\%$ of soil retention played an important role in sustaining the human well-being in downstream regions. Our approach offers a reference for building a telecoupled decision-making for other regions based on interregional flows. Moreover, the results of this study provide insights into interregional dependency on and responsibility for the transboundary ES impacts, and can help in sustainable development of watersheds by achieving environmental equality through guiding transboundary management.

Pressure dependent modeling (PDM) for water distribution systems (WDSs) is now widely accepted as being much more realistic than the previously used demand driven modeling. Steady-state linkflows, $q$, outflows, $c$, and heads, $h$, of a PDM WDS with no controls of flow and pressure in the system can reliably be found as the active set method solution of a linear-equality-constrained nonlinear optimization of the system’s content. Introducing linkflow controls, such as flow control valves (FCVs) and check valves can be handled by imposing box constraints on the decision variables $q$ and $c$ in the optimization; these problems can also be found either by an ASM or an interior point method. The heads in these problems are the Lagrange multipliers in the content model, and controlling these cannot be handled simply by imposing constraints on them. In this paper, the problem of modeling pressure-control devices such as pressure-reducing valves (PRVs) is solved by finding the Nash Equilibrium of a model that treats (1) the (global) linkflow constrained content optimization; and (2) the local pressure controls, as players in a competitive, noncooperative game. While this paper details how to model FCVs and PRVs together, this modeling framework is equally applicable to pressure-sustaining valves and variable speed pumps for pressure control without essential modification. An important contribution of this proof-of-concept paper is the development of a comprehensive model that includes flow and pressure controls and which finds a solution without using heuristics. The new method is illustrated on some examples.

Saltwater intrusion is a pervasive threat to coastal ecosystems. Common management strategies entail the installment of engineered flow control structures, though there is a dearth of work on their prevalence across the landscape and how different structures impact salinity under various hydrologic conditions. We manually classified more than 900 structures with most either being culvert pipes or riser structures. We then investigated how these structures impacted salinity in surface waters after the landfall of Hurricane Florence in 2018 and during the Summer of 2020. To accomplish this, we combined longitudinal and depth surveys, with long-term monitoring of salinity up and downstream of three flow control structures. Our results reveal that a flow control structure’s ability to exclude or trap saltwater from/in upstream environments depends on its position inland and design. Engineered structures were effective at excluding saltwater, while unintentional structures sometimes trapped saltwater in upstream environments. This work sheds light on important factors land managers should consider when putting in place new structures for freshwater management purposes.

Abstract

Idaho is one of the fastest-growing states in the US. The stressors of population growth and climate change are increasing the strain on its water resources, emphasizing the need for water management strategies. Public support, however, can vary by a range of factors, including geography. This study aims to assess the rural and urban distinctions of support for water resource management. In 2014, 401 people from Idaho’s general public responded to an online survey, with 375 of the respondents georeferenced into three groups: urban areas; urban clusters (small towns); and rural. The responses showed similarities in support among the groups; however, there were some notable differences. Water conservation received the most support for all groups, but there was a significant difference around land use regulations. The majority of respondents supported land use regulations, with urban clusters having the highest level of support. These findings can assist water managers throughout the United States with respect to recognizing public preferences in different geographies of residence.

Practical Applications

The findings from this study are relevant to water managers and decision-makers as they develop strategies to address water shortages. Results show that individuals in rural and urban communities alike share strong support for water conservation, including the reuse of water. Land use planning and regulation can be controversial; however, there is support to regulate development in order to protect water resources. Elected officials, decision-makers, and managers should understand that, on the surface, it may appear there is strong support for the development of new infrastructure, including dams and pipelines, but the results here show that support all but dries up when these efforts involve moving water from one community to another. Overall, this study showed that individuals in rural and urban communities support water conservation and land use planning to address water shortages. They do not, however, support the transfer, sale, or movement of water from one area to another. This is relevant, as water transfers are increasingly being used in the West to address water shortages. Most importantly, water managers and elected officials need understand that, when it comes to water, rural and urban communities are more alike than different.