Complexity in microbial metabolic processes in soil nitrogen modeling: a case for model averaging

Model uncertainty is rarely considered in the field of biogeochemical modeling. The standard biogeochemical modeling approach is to proceed based on one selected model with the “right” complexity level based on data availability. However, other plausible models can result in dissimilar answer to the scientific question in hand using the same set of data. Relying on a single model can lead to underestimation of uncertainty associated with the results and therefore lead to unreliable conclusions. Multi-model ensemble strategy is a means to exploit the diversity of skillful predictions from different models with multiple levels of complexity. The aim of this paper is two fold, first to explore the impact of a model’s complexity level on the accuracy of the end results and second to introduce a probabilistic multi-model strategy in the context of a process-based biogeochemical model. We developed three different versions of a biogeochemical model, TOUGHREACT-N, with various complexity levels. Each one of these models was calibrated against the observed data from a tomato field in Western Sacramento County, California, and considered two different weighting sets on the objective function. This way we created a set of six ensemble members. The Bayesian Model Averaging (BMA) approach was then used to combine these ensemble members by the likelihood that an individual model is correct given the observations. Our results demonstrated that none of the models regardless of their complexity level under both weighting schemes were capable of representing all the different processes within our study field. Later we found that it is also valuable to explore BMA to assess the structural inadequacy inherent in each model. The performance of BMA expected prediction is generally superior to the individual models included in the ensemble especially when it comes to predicting gas emissions. The BMA assessed 95% uncertainty bounds bracket 90–100% of the observations. The results clearly indicate the need to consider a multi-model ensemble strategy over a single model selection in biogeochemical modeling study

Do water savings persist? Using survival models to plan for long-term responses to extreme drought

Water utilities must maintain reliable service in a world where climate shocks and other socio-economic and health stressors are likely to disrupt water availability and demand more frequently. Understanding short- and long-term customer responses to these salient events is critical for infrastructure planning and capital investment. Although the short-term demand impacts of extreme droughts and related policy measures have been studied extensively, less is known about how these impacts persist—especially when driven by public awareness, media coverage, or other external drivers. Here, we introduce a novel approach combining survival models and change detection to assess water demand conservation ‘survival’ and rebound, using this method to analyze residential water demand in Costa Mesa, California after the state’s record-breaking 2012–2016 drought. We find that, of 54% of customers with detected savings in 2014–2015, just 25% rebounded to prior consumption levels after 5 years, implying mean conservation survival of 8 years. Survival was greater in young and politically progressive neighborhoods, smaller in residences with occupancy changes, and not significantly associated with water-efficiency rebates. Comparing the 2012–2016 drought to California’s milder 2007–2009 drought shows no evidence that drought severity associated with water savings persistence. This study presents an innovative approach to measure impacts of various stressors and their long-term water demand impacts. Our method enables utilities to more accurately discern structural changes in water demand, better informing strategic planning for short- and long-term water reliability and security

A Framework for Building Efficient Environmental Permitting Processes

Despite its importance as a tool for protecting air and water quality, and for mitigating impacts to protected species and ecosystems, the environmental permitting process is widely recognized to be inefficient and marked by delays. This article draws on a literature review and interviews with permitting practitioners to identify factors that contribute to delayed permit decisions. The sociopolitical context, projects that are complex or use novel technology, a fragmented and bureaucratic regulatory regime, serial permit applications and reviews, and applicant and permitting agency knowledge and resources each contribute to permitting inefficiency when they foster uncertainty, increase transaction costs, and allow divergent interests to multiply, yet remain unresolved. We then use the interviews to consider the potential of a collaborative dialogue between permitting agencies and applicants to mitigate these challenges, and argue that collaboration is well positioned to lessen permitting inefficiency

Fast in the pandemic, durable after droughts, inequal during economic downturn. A 20 year multi-dimensional retrospective analysis of water demand change in Southern California

Determining changes in water consumption behavior due to recurring external stressors (e.g. droughts and socio-economic fluctuations) and previously unseen shocks like the COVID-19 pandemic can support future demand-side management (DSM) programs and identifying vulnerable social groups. Yet, most studies analyzing external drivers of water consumption change are noncomparative as they examine only one stressor at the time, mainly droughts. Here we develop a multi-dimensional retrospective analysis (MDRA) to quantify residential water consumption changes in Southern California over the last two decades under compound hydroclimatic, economic, and pandemic stressors. We then uncover what socio-economic groups relate to predominant behavioral changes under each stressor. We observe a long-lasting decreasing water consumption trend for more than 76% of the analyzed households. Socio-economically vulnerable households were more likely to reduce water consumption during the economic and pandemic stressors. Differently, affluent neighborhoods tended to increase water consumption during or after droughts and the pandemic. Our MDRA supports utilities and policy makers to discern the impacts of different stressors on water demand and helps to identify social and economic sensitivities across a service area to develop adaptive DSMs and assistance programs

Groundwater Management and the Cost of Reduced Surface Water Deliveries to Urban Areas: The Case of the Central and West Coast Basins of Southern California

The Central and West Coast groundwater basins (“basins” or “Central and West Coast Basins”) are located in southern Los Angeles County. Groundwater produced from these basins provides approximately forty percent of the water supply for residents and businesses in all or parts of 43 cities. The 4 million residents in the area comprise more than ten percent of the total population of the State of California.This report measures the economic costs and benefits of the various program elements encompassed by the proposed judgment amendments (Judgment Amendments) to pumpers extracting groundwater in the basins. Because those pumpers include water agencies, who collectively serve nearly 4 million customers the economic costs and benefits also extend to the region as a whole. The analysis calculates such costs and benefits by modeling basin storage, water supply augmentation, replenishment and water leasing activities, taking into account variations in the availability of imported water. The analysis is conducted at an aggregate level, which means the collection of all water agencies and entities in the Central and West Coast Basins. The analysis conservatively examines only the benefits that would accrue to the current holders of adjudicated groundwater rights in the Basins and does not attempt to quantify the direct or indirect benefits that may accrue to other entities (e.g., entities that may seek to access the “regional” storage space). Benefits are expressed in both annual and present value terms, with present values calculated in 2009 dollars. The potential benefits are calculated based on the use of the storage space by a groundwater right holder whether through a priority right granted under the Judgment Amendments or on a “space available, at risk of spill” basis. Finally, the time frame for the analysis is 2009-2030, the term of the Judgment Amendments

Groundwater Management and the Cost of Reduced Surface Water Deliveries to Urban Areas: The Case of the Central and West Coast Basins of Southern California

The Central and West Coast groundwater basins (“basins” or “Central and West Coast Basins”) are located in southern Los Angeles County. Groundwater produced from these basins provides approximately forty percent of the water supply for residents and businesses in all or parts of 43 cities. The 4 million residents in the area comprise more than ten percent of the total population of the State of California. This report measures the economic costs and benefits of the various program elements encompassed by the proposed judgment amendments (Judgment Amendments) to pumpers extracting groundwater in the basins. Because those pumpers include water agencies, who collectively serve nearly 4 million customers the economic costs and benefits also extend to the region as a whole. The analysis calculates such costs and benefits by modeling basin storage, water supply augmentation, replenishment and water leasing activities, taking into account variations in the availability of imported water. The analysis is conducted at an aggregate level, which means the collection of all water agencies and entities in the Central and West Coast Basins. The analysis conservatively examines only the benefits that would accrue to the current holders of adjudicated groundwater rights in the Basins and does not attempt to quantify the direct or indirect benefits that may accrue to other entities (e.g., entities that may seek to access the “regional” storage space). Benefits are expressed in both annual and present value terms, with present values calculated in 2009 dollars. The potential benefits are calculated based on the use of the storage space by a groundwater right holder whether through a priority right granted under the Judgment Amendments or on a “space available, at risk of spill” basis. Finally, the time frame for the analysis is 2009-2030, the term of the Judgment Amendments

Groundwater Management and the Cost of Reduced Surface Water Deliveries to Urban Areas: The Case of the Central and West Coast Basins of Southern California

The Central and West Coast groundwater basins (“basins†or “Central and West Coast Basinsâ€) are located in southern Los Angeles County. Groundwater produced from these basins provides approximately forty percent of the water supply for residents and businesses in all or parts of 43 cities. The 4 million residents in the area comprise more than ten percent of the total population of the State of California. This report measures the economic costs and benefits of the various program elements encompassed by the proposed judgment amendments (Judgment Amendments) to pumpers extracting groundwater in the basins. Because those pumpers include water agencies, who collectively serve nearly 4 million customers the economic costs and benefits also extend to the region as a whole. The analysis calculates such costs and benefits by modeling basin storage, water supply augmentation, replenishment and water leasing activities, taking into account variations in the availability of imported water. The analysis is conducted at an aggregate level, which means the collection of all water agencies and entities in the Central and West Coast Basins. The analysis conservatively examines only the benefits that would accrue to the current holders of adjudicated groundwater rights in the Basins and does not attempt to quantify the direct or indirect benefits that may accrue to other entities (e.g., entities that may seek to access the “regional†storage space). Benefits are expressed in both annual and present value terms, with present values calculated in 2009 dollars. The potential benefits are calculated based on the use of the storage space by a groundwater right holder whether through a priority right granted under the Judgment Amendments or on a “space available, at risk of spill†basis. Finally, the time frame for the analysis is 2009-2030, the term of the Judgment Amendments.groundwater, water supply, water costs, water demand, Natural Resources and Conservation

Groundwater management and the cost of reduced surface water deliveries to urban areas: The case of the central and west coast basins of southern california

The Central and West Coast groundwater basins (“basins” or “Central and West Coast Basins”) are located in southern Los Angeles County. Groundwater produced from these basins provides approximately forty percent of the water supply for residents and businesses in all or parts of 43 cities. The 4 million residents in the area comprise more than ten percent of the total population of the State of California. This report measures the economic costs and benefits of the various program elements encompassed by the proposed judgment amendments (Judgment Amendments) to pumpers extracting groundwater in the basins. Because those pumpers include water agencies, who collectively serve nearly 4 million customers the economic costs and benefits also extend to the region as a whole. The analysis calculates such costs and benefits by modeling basin storage, water supply augmentation, replenishment and water leasing activities, taking into account variations in the availability of imported water. The analysis is conducted at an aggregate level, which means the collection of all water agencies and entities in the Central and West Coast Basins. The analysis conservatively examines only the benefits that would accrue to the current holders of adjudicated groundwater rights in the Basins and does not attempt to quantify the direct or indirect benefits that may accrue to other entities (e.g., entities that may seek to access the “regional” storage space). Benefits are expressed in both annual and present value terms, with present values calculated in 2009 dollars. The potential benefits are calculated based on the use of the storage space by a groundwater right holder whether through a priority right granted under the Judgment Amendments or on a “space available, at risk of spill” basis. Finally, the time frame for the analysis is 2009-2030, the term of the Judgment Amendments.groundwater, water supply, water costs, water demand

Economic impacts of reduced delta exports resulting from the wanger interim order for delta smelt

water transfers, water supply, water demand, water conservation