Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on January 5, 2010. Major professor: David Pilliod, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Biology." "December 2009." Includes bibliographical references. Also available on microfiche.

At the turn of the century, Kanab Creek incised 30-meters into its alluvium, leaving behind fluvial terraces and thick basin fill sediments exposed along arroyo walls. Research objectives were to determine the timing and causes of past valley-filling and arroyo-cutting episodes along a 20 km-long reach of Kanab Creek in southern Utah. Fluvial deposits were mapped at the 1:12,000 scale and sediments were described and dated using Optically Stimulated Luminescence (OSL) and radiocarbon dating. The Kanab Creek valley can be divided into a narrow, upper terraced reach and a broad lower basin fill reach near Kanab, Utah. The most prominent terrace in the upper reach is Quaternary alluvial terrace 4 (Qat4), followed by Qat3, Qat2/3, and Qat2 map units. These are composed of tabular-bedded, fine-grained sand, silt, and clay layers. The Qat2/3 map unit is a both a fill and fill-cut terrace underlain by Qa4, Qa3, and Qa2 alluvium and is used when the Qat3 fill-cut (fill-strath) terrace can not be differentiated from the Qat2 fill terrace due to their similar geomorphic position. The Qat3 fill-cut terrace upstream correlates to ~8 meters of aggradation downstream. The youngest terrace, Qat1, is a minor terrace, composed of coarse-grained channel facies. More recent channel and floodplain deposits were deposited over the last century following arroyo cutting. OSL and radiocarbon results suggest at least four cycles of fluvial cutting and filling: >6-3.5ka (Qa4), ~3->1ka (Qa3), 0.7-0.12ka (Qa2), and post-1880 AD (Qa1). Correlation to regional climate records suggests major periods of aggradation correlate to regionally cooler and wetter climatic intervals. Periods of arroyo cutting occurred at >6ka, ~3ka, 1-0.7ka, and during historic arroyo cutting (1882-1914 AD), and correlate to regionally warmer, drier intervals. These periods of aggradation and incision are roughly contemporaneous with regional drainages, except for the large aggradation seen in Kanab Creek 6-3.5ka (Qa4). Analysis of terrace longitudinal profiles indicates Qat4 has the lowest concavity suggesting that Qat4 aggraded during a period of greater sediment supply and/or reduced flood regime. Although OSL samples exhibited some degree of incomplete zeroing, calculated ages using a minimum age model are consistent with radiocarbon results.

155 pages / In the stratigraphic record of Camp Creek are episodes of fluvial scour and fill thousands of years old. Radiocarbon dates and the Mazama tephra, which serves as a stratigraphic time line, temporally bracket episodes of vertical aggradation and incision. Before 9000 years B.P. the valley floor was scoured to the Tertiary bedrock. Aggradation dominated since that time. Large cut-and-fill structures indicate that two periods of erosion occurred prior to incision of the modern arroyo. The first occurred before 6800 yr B.P. and the second occurred approximately 3000 years ago. The modern arroyo-channel flows at or near the Tertiary bedrock, is entrenched as much as nine meters in the valley-fill alluvium and is thought to have originated during the late 19th century.

PHYTOREMEDIATION OF WEATHERED PETROLEUM IN GROUNDWATER BY ARROYO WILLOWS IN NUTRIENT AMENDED ON-SITE MESOCOSMS SARAH BRAGG-FLAVAN A large-scale mesocosm study was conducted to determine if vegetation with willow trees enhances biodegradation and to evaluate the mechanisms of natural biodegradation of weathered petroleum compounds under field conditions. The mesocosms were designed to model conditions at a former oil field where mid-range petroleum distillates were used as a diluent for pumping crude oil contaminated the soil and groundwater at the site with petroleum compounds. Ten mesocosms were constructed at the field site using un-impacted soil and diluent-impacted groundwater from the site. Five of the mesocosms were planted with Arroyo Willow trees native to the field site and the other five served as controls without trees. Since these willow trees are phreatophytes, their roots are capable of consuming water from the water table. A previous study was conducted using these mesocosms, however the willow trees then were in poor condition. In this study, fertilizer was added to the mesocosms to promote healthy growth of the willows. Fertilizer was added equally to mesocosms with and without willow trees to avoid introducing bias. Groundwater was circulated through the mesocosms for two 109 to 126 days runs, while the total petroleum hydrocarbon (TPH) concentrations of the groundwater were measured periodically. Dissolved oxygen concentrations were also monitored in each of the mesocosms to determine if the willow trees had any impact on oxygen transfer to the subsurface. In the first run without nutrient amendments the trees did not enhance biodegradation. All the mesocosms started with an average TPH concentration of 6.3 mg/L and ended with a concentration of 1.0 mg/L. After this first run, nutrient amendments were added to all the mesocosms, resulting in healthy trees with robust growth. With healthy willow trees, the planted mesocosms resulted in a statistically significant increase in long-term biodegradation of dissolved-phase petroleum compounds. The planted mesocosms resulted in 29 percent more degradation. These results agree with prior lab studies using bench-scale microcosms with media from the former oil field which indicated that TPH concentrations after 100 days were lower in containers with willows or lupines compared to controls without plants. Microtox® toxicity decreased for both planted and control mesocosms, showing no toxic root exudates or by-products. There are several potential mechanisms of the observed phytoremediation. Terminal restriction fragment analyses showed that the planted mesocosms had different microbial communities than the unplanted mesocosms. Thus, a possible mechanism of the phytoremediation is stimulation of a rhizobial microbial community that biodegrades petroleum compounds. The dissolved oxygen (DO) concentrations were actually lower in the planted mesocosms, possibly due to consumption of oxygen during biodegradation of root exudates. The reduced DO concentrations in the planted mesocosm discounts the possibility that the plants stimulated biodegradation by increasing oxygen transfer to the subsurface. It is not known from these experiments if the petroleum compounds were taken up by the plants or if the plants stimulated bacterial biodegradation. Since it is difficult for plants to uptake non-polar compounds with a high octanol-water coefficient (Kow), it is usually unlikely that plants could uptake petroleum compounds which usually have a Kow > 3. However, the log Kow of the dissolved phase diluent determined in this research was only 0.14. Although the mechanism by which the willow trees increased biodegradation was not elucidated, this study demonstrated that phytoremediation of the polar and hydrophilic weathered petroleum compounds was successful. Column chromatography was used to fractionate petroleum compounds extracted from the groundwater into aliphatic, aromatic and polar components so that biodegradation of each of these fractions could be determined independently. The first mesocosm experiments showed that regardless of the presence of trees, there was a decrease in TPH concentration for all three fractions. The overall unfractionated biodegradation rates averaged 41 ug/L/day over this experiment, and the biodegradation rate of the polar fraction was similar at 40 ug/L/day. In comparison, the biodegradation rates of the aliphatic and aromatic fractions were considerably lower at 1.2 and 2.6 ug/L/day, respectively.

Arroyos are entrenched channels characterized by near-vertical walls of alluvium and flat channel bottoms. Historic channel entrenchment in the southwest United States during the late AD 1800s and early 1900s has stimulated extensive research on these dynamic fluvial systems. The near-synchronous episodes of arroyo entrenchment and aggradation in Kanab Creek and other drainages in southern Utah during the last ~1 Ka has led many researches to argue that hydroclimatic forcings drive arroyo processes. These hypotheses remain largely untested, and there remains considerable uncertainty regarding the timing of these events and the specific mechanisms responsible for arroyo formations. Previous work established an alluvial chronology for the kanab canyon reach of Kanab creek, but it remained unclear if arroyo events in this reach were continuous with those downstream or synchronous with events in the disconnected arroyo in the upper basin. Using deailed sedimentologic and stratigraphic descriptions coupled with AMS radiocarbon and optically stimulated luminescence (OSL) dating, a new chronostratigraphic record of arroyo entrenchment and aggradation for kanab creek is produced in this study. Results suggest at least five periods of fluvial aggradation and episodic arroyo entrenchment during the middle-to late-Holocene, with aggradation occuring from ~6.2 to 3.67 ka (Qfl), ~3.2 to 2.5 ka (Qf2), ~2.2 to `.45 ka (Qf3), 1.4 to 0.8 ka (Qf4), and 0.75 to 0.14 ka (Qf5). This record is compared to regional alluvial and paleoclimate records to explore potential allogenic and autogenic forcing mechanisms. Rapid transitions from exceptional drought to pluvial periods are quasi-synchronous with regional arroyo entrenchment over the last ~1.5 Ka, but the lack of clear correlations amongst the regional alluvial records and between paleoclimate records beyond 1.5 Ka suggests that internal geomorphic thresholds are important controls on the timing of entrenchment in individual catchments. Previous research on arroyo dynamics has largely focused on the timing of entrenchment. The few studies that have investigated the processes related to aggradation have used historic observations, and not the stratigraphic record of arroyo deposits. In this study, the alluvial records from three reaches of Kanab Creek are combined to test models of the processes and geometric patterns of paleoarroyo aggradation. Results indicate that aggradation initially propagates upstream and then transitions to synchronous vertical aggradation along the entire channel profile as arroyos approach complete filling.

Most approaches to interpreting alluvial records in drylands fall into one of two categories: (1) The "arroyo problem," wherein workers study cycles of streambed aggradation and degradation in broad, unconstricted alluvial valleys; and (2) paleoflood hydrology, where alluvial sequences in constricted bedrock canyons are interpreted as paleoflood deposits from streams with stable channel grade and geometry. Both approaches can be valid in their end-member settings, but there is confusion about how the two record types relate in a single drainage. We address this disconnect in Buckskin Wash, an ephemeral stream that consists of a broad alluvial reach draining into a tightly constricted slot canyon. By employing detailed sedimentology, stratigraphy, and geochronology in both the alluvial and constricted reaches of the watershed, we test the hypothesis that the slot canyon deposits are anticorrelated to valley-fill deposits upstream, implying that arroyo cutting is driven by episodic flooding. Alluvial reach deposits are characterized by stratal packages representing incremental, long-term aggradation bound by erosion surfaces representing channel entrenchment. At least four packages younger than ~3 ka are present, the youngest spanning ~0.7 - 0.15 ka. Each is composed of interfingering imbricated gravels, laminated sands, and massive silty clays. Constricted reach deposits consist of five discrete packages, each composed of tabular beds of laminated silty sand that were deposited relatively rapidly. The oldest package dates to ~1.9 - 1.1 ka, whereas the rest of the deposits are younger than ~0.15 ka. Traditional paleoflood techniques would suggest that the constricted reach deposits record a ~1000-year absence of paleofloods followed by ~100 years of frequent, high-magnitude flooding that indeed correlate to arroyo cutting upstream. We argue instead that the constricted reach deposits record an episode of higher preservation potential. Transport of sediment from the alluvial reaches during historic arroyo cutting likely led to a pulse of sediment storage and changed stage-discharge relations in the slot canyon downstream, allowing even moderate floods to overtop existing deposits and be preserved. This new interpretation suggests that, because preservation may be a function of episodic sediment loading from upstream, constricted-reach deposits may not accurately record the paleoflood history of a stream.

The arroyo toad (Anaxyrus californicus) is a federally endangered species found on Fort Hunter Liggett, Monterey County, California. The species was discovered in 1996 and was determined to occupy 26.7 km of the San Antonio River from approximately 2.4 km northwest of the San Antonio Mission de Padua, to the river delta above the San Antonio Reservoir. The construction of the San Antonio Reservoir dam in 1963 isolated this northern population of arroyo toads. Through time, the Fort Hunter Liggett landscape has changed drastically. The land was heavily grazed by cattle until 1991, which considerably reduced vegetation in riparian areas. Military training following acquisition of the land in 1940 far exceeded current allowable training. Fire was used extensively to reduce unfavorable vegetation, and as a result, extreme tree loss occurred through the ranges. Today cattle grazing is prohibited and military activity is restricted from riparian corridors. While riparian vegetation continues to recover in the San Antonio River, habitat for breeding arroyo toads has become less suitable. To improve conservation efforts and management of this endangered species, I have provided a thorough assessment of the life history of arroyo toads specific to Fort Hunter Liggett and identified the status and current threats to the population on the installation. I have also prepared a habitat assessment of the San Antonio River in the arroyo toad range, quantified habitat conversion, and identified areas that may no longer provide suitable breeding habitat for the species. The research conducted for this report is preliminary to restoration efforts that are inevitable to ensure recovery of the endangered species at Fort Hunter Liggett.

La presente tesis doctoral aborda el estudio de las variables físico-naturales y antropogénicas que gobiernan la dinámica hidrográfica de la cuenca del arroyo Sauce Corto y sus implicancias en los procesos de inundaciones y anegamientos. El área de estudio se localiza en el suroeste de la provincia de Buenos Aires, con sus cabeceras en la vertiente nororiental del Sistema de Ventania y su nivel de base en las lagunas Inchauspe y de Juancho. Se estudiaron las características climáticas a través de los principales elementos que las definen: temperatura, viento y precipitaciones. En este último caso se profundizó en las variaciones en el tiempo y en el espacio a diversas escalas temporales. Se analizaron índices de anomalías de precipitación que permitieron identificar y caracterizar según duración e intensidad períodos secos y húmedos. Se obtuvieron y analizaron datos de caudal conjuntamente con las precipitaciones que posibilitaron identificar el régimen pluvial de alimentación del arroyo Sauce Corto. Se realizó un análisis morfométrico detallado de las principales subcuencas que conforman la cuenca alta del arroyo Sauce Corto a fin de identificar comportamientos diferenciales respecto de la potencialidad para generar crecidas. Se analizó la peligrosidad de cada subcuenca y de la cuenca alta en su conjunto. Se identificaron las principales obras de arte ejecutadas en la cuenca y su influencia en la dinámica hidrográfica. Se abordó el estudio de eventos históricos de inundación y anegamiento mediante la aplicación de imágenes satelitales. Se definieron zonas afectadas por dichos procesos. Mediante el desarrollo del estudio se pudo comprobar que las subcuencas con mayor peligrosidad son Cerro 832, Nacimiento Oeste, Nacimiento Este. No obstante ello, se comprobó también que los mayores efectos adversos para la población y sus actividades se deben a la peligrosidad de la cuenca alta en su conjunto. Por esta razón, las crecidas que afectan a la cuenca alta y media del arroyo Sauce Corto se deben controlar mediante obras de retención y almacenamiento de acuerdo a la dinámica de cada subcuenca. / This doctoral thesis studies the natural-physical and anthropogenic factors that govern hydrographic dynamic of the Sauce Corto basin and their implication in the processes of flooding and waterlogging. The study area is located in the southwest of the Buenos Aires province, its headwaters are in the north-east side of the Ventania System and its base level in the Inchauspe.and Juancho lagoons. Climatic characteristics were studied through the main elements that define them: temperature, wind and rainfall. In the last case, the analysis was focused on the temporal and spatial variations at different time scales. Precipitation anomalies indices were analyzed and these results helped identify and characterize the duration and intensity of the dry and wet periods. Discharge measures were obtained and analyzed as well as rainfall amouns which allowed to identify the Sauce Corto basin ́s water regime is controlled by rainfalls It was executed a detailed morphometric analysis of the major sub-basins of the Sauce Corto upper basin in order to identify differential behaviors regarding to its potential of flooding. The dangerousness of each sub-basin and as well as the upper basin was analyzed. The major works of art executed in the basin and its influence on its dynamics basin were identified. The study of flood and waterlogging historical events was made by applying satellite images. Affected areas by these processes were defined as well. Through the development of the study it was found that the most hazardous sub-basins are: Cerro 832, Nacimiento Oeste and Nacimiento Este. Nevertheless, it was also found that the most important harm to population and its activities is due to the dangerousness of the upper basin as a whole. For this reason, the floods that affects upper and middle basin of the Sauce Corto creek should be controlled by retention and storage constructions according to the dynamics of each sub-basin.

Esta pesquisa teve como objetivo principal o mapeamento das áreas suscetíveis à inundação na Bacia Hidrográfica do Arroio do Salso, em vista da acelerada ocupação que vem se processando nos últimos anos e diante de uma perspectiva de urbanização cada vez mais intensa em curto e em médio prazos. Esta bacia, que é a maior do município, está localizada na zona sul de Porto Alegre, capital do Estado do Rio Grande do Sul, e atualmente constitui-se em uma nova “fronteira” de avanço da ocupação, inclusive irregular. O município tem um conhecido histórico de inundações, devido, entre outras causas, à existência de quase um terço de terras no mesmo nível dos rios, à riqueza hídrica da Região Hidrográfica do Guaíba e às características climáticas atuantes no Estado do Rio Grande do Sul – aliadas a um intenso processo de urbanização, que altera intensamente a dinâmica natural da drenagem. Embora as inundações sejam fenômenos cíclicos e naturais, testemunhos da dinâmica do ambiente que nos envolve, podem ser potencializadas pela ação do homem, o que justifica a busca da minimização de suas consequências por meio, sobretudo, da regulação da ocupação do espaço. Visando o reconhecimento dos condicionantes destes eventos, foi utilizada uma metodologia geográfica de pesquisa integrada, com a visão sistêmica proporcionada pela escolha da bacia hidrográfica como unidade de análise. A análise ambiental foi executada com ênfase geomorfológica, englobando os múltiplos fatores - naturais e antrópicos - que contribuem para a conformação da realidade local, sempre na perspectiva de um processo dinâmico e permanentemente ativo. Foram pesquisados os eventos de inundações na bacia, os padrões de precipitação local, a resposta de uma seção transversal do Arroio do Salso às chuvas intensas, as características geomorfológicas, geológicas e pedológicas da bacia e o uso e ocupação do solo. Os dados obtidos, incluindo as observações de campo, foram analisados e sintetizados graficamente em forma de mapas e a pesquisa demonstrou que há uma grande área suscetível a eventos de transbordamento do Arroio do Salso, ocorrendo frequentes prejuízos e transtornos às populações carentes do entorno. Foi possível demonstrar que a bacia apresenta características naturais que a tornam muito suscetível à inundação – o que é potencializado pela ação humana, que causa o aumento da vazão de pico, o estrangulamento da drenagem e o assoreamento dos canais. Associando-se, principalmente, as áreas de baixas declividades com solos de pequena capacidade de drenagem, foi possível identificar as áreas mais suscetíveis à ocorrência de inundação na bacia, bem como os pontos em que a ação humana intensifica esta suscetibilidade natural. A experiência da Bacia Hidrográfica do Arroio do Salso demonstra claramente que a urbanização intensa, sobretudo quando não é planejada para minimizar os impactos ambientais, pode resultar em grandes alterações na dinâmica hídrica natural. Como o próprio homem acaba por ser o maior prejudicado, a delimitação de áreas de ocupação previne estes riscos - e o mapeamento é um instrumento fundamental neste processo. / This research was aimed at mapping areas susceptible to flooding in the hydrographic basin of the Arroyo Salso in view of the rapid occupation that have been occurring in recent years and facing the prospect of urbanization increasingly intense in short and medium period of time. This basin, which is the largest of the city, nowadays, is a new "frontier" in advance of occupation, inclusively irregular. The city has a known history of flooding due to, among other reasons, the existence of almost one third of the lands in the same level of the rivers, the hydric wealth of the Guaíba Hydrographic region and climatic features operating in the State of Rio Grande do Sul - associated with an intense process of urbanization, which strongly changes the dynamics of natural drainage. Although floods are natural cyclic phenomena and as testimony of the dynamic environment that surrounds us, can be leveraged by man, which justifies the search for minimizing the consequences through, especially, the regulation of the use of space. For recognition of conditions of these events, we used a methodology geographical research integrated with the systems view provided by the choice of the basin as the unit of analysis. The environmental analysis was performed with emphasis on geomorphology, encompassing many factors - natural and man-made - that contribute to the shaping of local circumstances, bearing in mind that a dynamic and constantly active. We examined the flood events in the basin, the patterns of local precipitation, the response of a cross section of the Salso to heavy rain, the geomorphological characteristics, geological and soil basin and the use and occupation of land. The data obtained, including field observations, were analyzed and summarized graphically in the form of maps and the research has shown that there is a large area subject to flooding events of the Arroyo Salso occurring often damages and troubles to needy populations of the surroundings. It was possible to show that the basin has natural features that make it very susceptible to flooding - which is aggravated by human action, which causes an increase in peak discharge, the bottleneck in the drainage and siltation of the channels. Joining, mainly, the areas of lower slopes with little soil drainage capacity, it was possible to identify the areas at highest risk of flooding in the basin, as well as the points where human action intensifies this natural susceptibility. The experience of hydrographic basin of the Arroyo Salso clearly demonstrates that intensive urbanization, especially when it is not planned to minimize environmental impacts, can result in great changes in the natural hydric dynamics. As the man turns out to be the most affected, the delimitation of areas of occupation prevents these risks - and the mapping is a key tool in this process.

The purpose of this professional project is to address the practical implications of decentralized greywater usage in the City of Arroyo Grande. This professional project consists of two products: a brief greywater guide for the City and a background report. The greywater guide is intended for city planners to use for general information about greywater systems. The guide addresses Arroyo Grande’s potable water shortage; what greywater is; advantages and concerns about greywater use; plants that are tolerant and intolerant of greywater irrigation; appropriate detergents to use with a greywater system; and a summary of California greywater law. The background report discusses the City of Arroyo Grande’s potable water conditions and how water supply will be affected by growth projections for 2030. It is estimated that by the year 2030, Arroyo Grande’s water demand will outgrow its water supply by 283 acre feet. Future water shortages are a concern at a local level and also on a global level. Three case studies examine how water scarcity has prompted the successful use of greywater. These studies examine the Hashemite Kingdom of Jordan; the Casa del Agua project in Arizona; and a local study in Santa Barbara, California. The report concludes with California greywater law, and how the recent change in August, 2009 has greatly increased the legal accessibility of greywater reuse as an obtainable method of water conservation. In combination with education and outreach among city officials and residents, greywater has potential to play a main role in water conservation in Arroyo Grande.