California faces a complex agricultural, environmental, and legal crisis regarding the management of precious water and soils around the state. Most water supplies are either increasingly polluted groundwater or snowmelt stored in reservoirs whose construction and operation has devastated Pacific salmonid populations, among other aquatic and riparian organisms. Meanwhile, intensive agriculture and logging are eroding away fertile soils, which limits the sustainable use of farmland, snuffs riverine habitat, and imposes a legal quagmire in implementation of EPA’s Total Maximum Daily Load (TMDL) requirements. The complexity of problems require teams of experts cutting across disciplines and across academic-government-practitioner boundaries to work together to come up with solutions. Unfortunately, the University of California has systematically abandoned it expertise in the area of water science and sediment transport, as indicated by a steady decline of hydrology and sediment transport professors, destruction of hydraulics laboratories (O’Brien Hall at UCB and the Hydraulics Lab behind Veihmeyer Hall at UCD), and mothballing of remaining research flumes. Within this milieu, I am one of the last remaining experts on river hydraulics and sediment transport in the UC system and I am overwhelmed by the amount of requests I receive for help with these problems.
There are three elements to my Agricultural Experiment Station mission:
- AES mission-oriented outreach and a current, active, and approved AES project focused on providing technical support regarding evaluation of a) water operations at the watershed scale and b) alternative non-water riverine mitigation measures on river landforms and ecological functions toward achieving a sustainable balance of human water use and ecosystem services.
- Mission-related research on the effects of eroded farmland, rangeland, and wildland soils on river channels, the coastal zone, and the ocean.
- Additional research related to my AES mission
Mission-Oriented Outreach And Clientele
During the last five years I have adhered to a strict interpretation of mission-oriented outreach as activities that directly serve agricultural and environmental clientele. My primary area of outreach has been providing advice, technical analysis, and education to government agencies (e.g. USFWS, CDFG, USBR, DWR), non-governmental organizations (SYRCL and YRPF), water and power utilities (EBMUD, PG&E, CEC, YCWA), private landowners, and news media on the evaluation of river landforms and ecological functions when considering reservoir reoperations and alternatives to that in terms of in-channel river rehabilitation to a broad range of clientele. The reservoirs I have worked on provide water to farms throughout the Central Valley as well as population centers in Sacramento and the Bay Area. For a decade I have been the lead designer of river rehabilitation projects for the lower Mokelumne River. I also designed a river rehabilitation project for the Trinity River below Lewiston Dam and I designed a gravel augmentation pilot project for the Yuba River below Englebright Dam. In addition, I trained managers of the American and Feather Rivers, and they have used my rehabilitation framework to design multiyear projects on those rivers. Beginning in 2009 I began to advise the River Management Team of the Yuba Accord and I played a significant role in the development of a 5-year monitoring and evaluation plan that will guide water reoperations under the Accord, dam relicensing, and river rehabilitation in the Yuba basin. I participate in regular meetings of the Accord managers to help advise them on river management. I am also working with the California Energy Commission to investigate advanced methods for studying the effects of high elevation dams on river processes and ecological functions. In short, a substantial fraction of the large rivers draining the northern Central Valley are being influenced by my research and recommendations. In 2007 I was interviewed by a TV production company for a show about the hydraulics of Niagara Falls (“Conquering Niagara”) that premiered on the National Geographic Channel. That show appears on a regular basis on several cable channels.
Current, Active, and Approved AES Projects
During the last five years I have focused on a single broad hatch project and I have conducted other AES-related research outside of that project. The purpose of my hatch project has been to develop and test new science-based, interdisciplinary tools and approaches for assessing riverine landforms, processes, and ecological functions in relations to options for reoperating reservoirs and/or rehabilitating rivers in California. My group has done a lot of exploration of specific ecohydraulic mechanisms in which the variations of channel shape drive shifts in physical processes and ecosystem services as discharge changes. That enables river managers to determine the best dam releases to make to meet key biological objectives. For example, in a series of publications my group investigated diverse combinations of local channel shape, discharge, and downstream hydraulic controls in several real and hypothetical rivers. We found that the mechanism of “flow convergence routing” that we proposed in a WRR journal article in 2006 is indeed present and is responsible for maintaining the diversity of riffles and pools in gravel-bed rivers. In turn, we found that these morphological units serve as the habitat for different fish species’ lifestages and that our simulation models were highly successful at predicting where fish were located in the rivers we studied. We also used one of the river rehabilitation projects we participated in to reinstate flow convergence routing into a river and then we found that after reinstatement this process functioned during a large flood to sustain and further enhance fish habitat. To further expand on our basic theory, we proposed the new mechanism of “reverse domino” riffle failure that explains how a gravel-bed channel re-organizes its morphological units when a large flood occurs. We also published a new conceptual framework and semi-analytical simulation in JGR that predicts the hydraulic conditions in waterfalls that occur through channel constrictions or expansions, which is a common occurrence in mountain rivers, because they have high variance in channel width. In terms of applied science, I led an engineering study into the effectiveness of front loaders to build complex river rehabilitation designs and I participated in a native plant restoration study with Professor Wallender. All of this scientific research has blended fundamental theoretical developments and applications to help manage real rivers in California.
Additional Research Related to AES Mission
In another line of research that is not under my hatch project, I have been investigating sediment fluxes in watersheds. I spent 2 years on a project looking at the problem of fine sediment deposition in the irrigation-dominated agricultural region south of the Salton Sea in the Imperial Irrigation District. Based on that work I published 5 journal articles that reported on suspended sediment dynamics and sediment deposition in agricultural drain channels in relation to different crop patterns and irrigation methods. More recently I have a $1.5 million grant from NSF to collaborate with colleagues in Oregon and at the USGS to study the flux of sediment and particulate organic carbon to the Pacific ocean from California and Oregon. For that project I have been monitoring materials moving through of the Salinas River, which is an intensively farmed basin terminating at Monterey Bay. I have also collected sediment cores from floodplains and the estuary, reconstructed sedimentation rates over the last 50 years, and found that wildfires and El Nino years have played a large role in exporting material to the ocean.