Both rural and urban development can lead to accelerated gully erosion. Quantifying erosion is challenging in environments where gullies are rapidly repaired, areas microtopographic complexity complicates the delineation of contributing areas. This study used unmanned aerial vehicles (UAVs) Structure-from-Motion (SfM) photogrammetric techniques quantify Los Laureles Canyon watershed, a urbanizing watershed Tijuana, Mexico. Following storm event, network extent was mapped using an orthomosaic...

Urbanization can increase sheet, rill, gully, and channel erosion. We quantified the sediment budget of Los Laureles Canyon watershed (LLCW), which is a mixed rural-urbanizing catchment in Northwestern Mexico, using AnnAGNPS model field measurements geometry. The was calibrated with five years observed runoff loads used to evaluate reduction under mitigation scenario involving paving roads hotspots Calibrated load had mean-percent-bias 28.4 - 8.1, root-mean-square errors 85% 41% mean,...

Environmental flow programs aim to protect aquatic habitats and species while recognizing competing water demands. Often this is done at the local or watershed level because it relatively easier address technical implementation challenges these scales. However, a consequence of approach that ecological criteria are developed for only few areas as dictated by funding interest with many streams neglected. Here we discuss collaborative development California Flows Framework (CEFF) an example...

Flows in urban rivers are increasingly managed to support water supply needs while also protecting and/or restoring instream ecological functions, goals that often opposition each other. Effluent-dominated (i.e., consist primarily of discharged treated wastewater) pose a particular challenge because changes effluent discharge may impact river ecology. A functional flows approach, which metrics from the annual hydrograph correspond processes, was applied understand hydro-ecological...

Environmental flows are critical to the recovery and conservation of freshwater ecosystems worldwide. However, estimating needed sustain ecosystem health across large, diverse landscapes is challenging. To advance protections environmental for streams in California, United States, we developed a statewide modeling approach focused on functional components natural flow regime. Functional California streams—fall pulse flows, wet season peak base spring recession dry baseflows—support essential...

Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination field surveys Structure-from-Motion (SfM) photogrammetry techniques was used document spatial patterns geometry a rapidly urbanizing watershed, Los Laureles Canyon (LLCW), Tijuana, Mexico. Ground-based SfM map dimensions with 1 2 cm vertical mean error for...

Modelling gully erosion in urban areas is challenging due to difficulties with equifinality and parameter identification, which complicates quantification of management impacts on runoff sediment production. We calibrated a model (AnnAGNPS) an ephemeral network that formed unpaved roads following storm event watershed (0.2 km2) Tijuana, Mexico. Latin hypercube sampling was used create 500 ensembles. Modelled load most sensitive the Soil Conservation Service (SCS) curve number, tillage depth...

Restoring the health of urban streams has many characteristics a wicked problem. Addressing problem requires managers, academics, practitioners, and community members to make negotiated tradeoffs compromises satisfy values perspectives diverse stakeholders involved in setting restoration project goals objectives. We conducted gap analysis on 11 stream projects identify disconnections, underperformance issues, missing processes structures used develop examined results investigate whether...

Flow alteration is a pervasive issue across highly urbanized watersheds that can impact the physical and biological condition of streams. In altered systems, flows may support novel ecosystems not have been found under natural conditions reference-based environmental flow targets be relevant. Moreover, stream impairments such as channel morphology make less effective in supporting ecosystem functions. Here, we develop an approach for determining ecological needs modified systems to existing...

Abstract Stream channel erosion, enlargement, and habitat degradation are ubiquitous in urban watersheds with conventional stormwater management that increase channel-eroding flows relative to undeveloped watersheds. Hydrologic-based restoration aims discharge a more natural flow regime via interventions. Whether such interventions facilitate geomorphic recovery depends, part, on the degree which they restrict discharges would otherwise contribute erosion. Erosion potential (E), ratio of...

Anthropogenic development has adversely affected river habitat and species diversity in urban rivers, existing habitats are jeopardized by future uncertainties water resources management climate. The Los Angeles River (LAR), for example, is a highly modified system that been mostly channelized flood control purposes, altered hydrologic hydraulic conditions, thermally (warmed), which severely limits the suitability cold fish species. Efforts currently underway to provide suitable...

Tijuana River watershed on the US-Mexico border, where urbanization, estuarine sedimentation, and beach erosion incentivize quantification of runoff suspended sediment loads (SSL) concentrations (SSC). Rainfall, SSL were quantified for 2001–2019 (storm-wise) 1962–2019 (annual) using rating curves bootstrapping to quantify uncertainty. Annual increased a given rainfall depth following channelization start imported water in 1978–79, during urbanization over 1980–2019. SSC fell between 1970 s...

Contaminants of emerging concern such as pharmaceuticals, personal care products, per- and polyfluoroalkyl substances, plasticizers, are ubiquitous in effluent-dominated rivers have potential adverse effects on humans aquatic life. Demands water supply prompted conservation reuse measures, impacting the discharge these rivers, yet management decisions quality largely intuited not quantified. This research examines how changes practices will impact concentrations contaminants concern,...

A key challenge in managing flow alteration is determining the severity and pattern of associated with degradation biological communities. Understanding these patterns helps managers prioritize locations for restoration management actions. However, choices made about how to use flow-ecology relationships can have profound implications on decisions (e.g., which endpoints, thresholds, seasonal components use). We describe a process using actions that 1) Represents most relevant annual...

Abstract Restoration of urban rivers must simultaneously design for ecological habitat while accounting altered flow regimes associated with runoff, flood protection, and industrial/wastewater discharge. The goal this study was to use targets guide channel restoration the Los Angeles (LA) River across potential future regimes. Using a one‐dimensional hydraulic model, we simulated range cross section configurations subject different management decisions (wastewater reuse, low‐flow [LF]...

Abstract Stream channel erosion, enlargement, and habitat degradation are ubiquitous in urban watersheds with conventional stormwater management. Hydrologic-based restoration aims to discharge a more natural flow regime via management interventions. Whether such interventions facilitate geomorphic recovery depends, part, on the degree which they restrict discharges that would otherwise contribute erosion. Erosion potential (E), ratio of post-developed predeveloped sediment transport...