Using heat to characterize streambed water flux variability in four stream reaches

Estimates of streambed water flux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to study the temporal and spatial variability of fluxes through the streambed. Synoptic methods (seepage meter and differential discharge measurements) were compared with estimates obtained by using heat as a tracer. Water flux was estimated by modeling one-dimensional vertical flow of water and heat using the model VS2DH. Flux was influenced by physical heterogeneity of the stream channel and temporal variability in stream and ground-water levels. During most of the study period (April-December 2004), flux was upward through the streambeds. At the IN, NE, and CA sites, high-stage events resulted in rapid reversal of flow direction inducing short-term surface-water flow into the streambed. During late summer at the IN site, regional ground-water levels dropped, leading to surface-water loss to ground water that resulted in drying of the ditch. Synoptic measurements of flux generally supported the model flux estimates. Water flow through the streambed was roughly an order of magnitude larger in the humid basins (IN and NE) than in the arid basins (WA and CA). Downward flux, in response to sudden high streamflows, and seasonal variability in flux was most pronounced in the humid basins and in high conductivity zones in the streambed.     

Biophysical‐Regulatory Classification and Profiling of Streams Across Management Units and Ecoregions1

Caruso, Brian S. and Joshua Haynes, 2011. Biophysical‐Regulatory Classification and Profiling of Streams Across Management Units and Ecoregions. Journal of the American Water Resources Association (JAWRA) 00(0):1‐22. DOI: 10.1111/j.1752‐1688.2010.00522.x Abstract: Aquatic resources management in the United States (U.S.) under Clean Water Act Section 404 has become more complex after recent Supreme Court decisions and U.S. Army Corps of Engineers and Environmental Protection Agency (USEPA) guidance. Many intermittent/ephemeral and headwater streams may not be jurisdictional if they lack a significant nexus with navigable waters. Streams in semiarid USEPA Region 8 were classified based on hydrologic permanence and stream order using National Hydrography Dataset (NHD) Plus and GIS to provide information across broad spatial scales to aid with jurisdictional determinations (JDs). Four classes were developed for profiling across management units and ecoregions. Based on medium‐resolution NHDPlus data, intermittent streams comprise >¾, and first order streams constitute >½ of the total stream length in Region 8. Mountain states and ecoregions have the largest percentage of perennial first order streams, whereas the Dakotas, plains, and desert ecoregions have the greatest percentages of intermittent first order and intermittent higher order streams. In the Upper Colorado River Basin, >50% of reaches are intermittent first order, and 9% are perennial first order. NHDPlus data can significantly underestimate the length of headwater and intermittent streams, but can still be a valuable tool to help develop stream classes and for regional JD planning and analysis. Refinement of the stream classes using high resolution NHD data and other key catchment parameters can improve their utility for JDs.     

Southwestern Intermittent and Ephemeral Stream Connectivity

Ephemeral and intermittent streams are abundant in the arid and semiarid landscapes of the Western and Southwestern United States (U.S.). Connectivity of ephemeral and intermittent streams to the relatively few perennial reaches through runoff is a major driver of the ecohydrology of the region. These streams supply water, sediment, nutrients, and biota to downstream reaches and rivers. In addition, they provide runoff to recharge alluvial and regional groundwater aquifers that support baseflow in perennial mainstem stream reaches over extended periods when little or no precipitation occurs. Episodic runoff, as well as groundwater inflow to surface water in streams support limited naturally occurring riparian communities. This paper provides an overview and comprehensive examination of factors affecting the hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams on perennial or intermittent rivers in the arid and semiarid Southwestern U.S. Connectivity as influenced and moderated through the physical landscape, climate, and human impacts to downstream waters or rivers is presented first at the broader Southwestern scale, and secondly drawing on a specific and more detailed example of the San Pedro Basin due to its history of extensive observations and research in the basin. A wide array of evidence clearly illustrates hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams throughout stream networks.     

EFFECTS OF LOMA PRIETA EARTHQUAKE ON SURFACE WATERS IN WADDELL VALLEY1

ABSTRACT: Waddell Creek is a perennial stream near Santa Cruz, California, which discharges into the Pacific Ocean about 38 km from the epicenter of the Loma Prieta earthquake (October 17, 1989, M 7.1). The earthquake caused no significant changes or damage to structures or surface features in the area, but was followed by an order of magnitude transient increase in discharge of Waddell Creek and nearby springs. The transients approximate a step rise followed by an exponential recession with time constants of from 37 to 59 days. The flow recession pattern of Waddell Creek was obscured by heavy rains after about 50 days; however, the springs maintained an exponential recession with minimal rain interference for periods of several time constants, then abruptly ceased flowing. A comparison of the pre-quake and post-quake chemical signature of one of the springs shows only minor changes in water chemistry indicating a common source for pre- and post-quake waters. Increased permeability of the subsurface ground material appears to be the most probable cause of the hydrologic changes. Post-seismic reduction of permeability has not been observed or inferred.     

Impacts of Variable Climate and Effluent Flows on the Transboundary Santa Cruz Aquifer

Assessing groundwater resources in the arid and semiarid borderlands of the United States and Mexico represents a challenge for land and water managers, particularly in the Transboundary Santa Cruz Aquifer (TSCA). Population growth, residential construction, and industrial activities have increased groundwater demand in the TSCA, in addition to wastewater treatment and sanitation demands. These activities, coupled with climate variability, influence the hydrology of the TSCA and emphasize the need for groundwater assessment tools for decision‐making purposes. This study assesses the impacts of changes in groundwater demand, effluent discharge, and climate uncertainties within the TSCA from downstream of the Nogales International Wastewater Treatment Plant to the northern boundary of the Santa Cruz Active Management Area. We use a conceptual water budget model to analyze the long‐term impact of the different components of potential recharge and water losses within the aquifer. Modeling results project a future that ranges from severe long‐term drying to positive wetting. This research improves the understanding of the impact of natural and anthropogenic variables on water sustainability, with an accessible methodology that can be globally applied.     

GROUNDWATER QUALITY IN THE CORTARO AREA NORTHWEST OF TUCSON,ARIZONA1

ABSTRACT The Cortaro Area is currently the depository for much of the liquid waste from the City of Tucson. In the past, more than one-half of the sewage effluent was used for crop irrigation. However, since 1970 virtually all of the sewage effluent has been percolated in the normally dry Santa Cruz River channel. Nitrate and chloride contents were monitored monthly in water samples from about 20 large-capacity irrigation wells. Contents and seasonal trends for these constituents were closely related to the disposal of sewage effluent. Water quality problems other than nitrate include total dissolved solids, boron, coliform, and lead. High lead contents in the area appear to be a natural phenomenon and the coliform contents are likely related to poor well construction. The other quality problems are primarily due to sewage effluent.     

Classification of Ephemeral,Intermittent, and Perennial Stream Reaches Using a TOPMODEL‐Based Approach

Whether a waterway is temporary or permanent influences regulatory protection guidelines, however, classification can be subjective due to a combination of factors, including time of year, antecedent moisture conditions, and previous experience of the field investigator. Our objective was to develop a standardized protocol using publically available spatial information to classify ephemeral, intermittent, and perennial streams. Our hypothesis was that field observations of flow along the stream channel could be compared to results from a hydrologic model, providing an objective method of how these stream reaches can be identified. Flow‐state sensors were placed at ephemeral, intermittent, and perennial stream reaches from May to December 2011 in the Appalachian coal basin of eastern Kentucky. This observed flow record was then used to calibrate the simulated saturation deficit in each channel reach based on the topographic wetness index used by TOPMODEL. Saturation deficit values were categorized as flow or no‐flow days, and the simulated record of streamflow was compared to the observed record. The hydrologic model was more accurate for simulating flow during the spring and fall seasons. However, the model effectively identified stream reaches as intermittent and perennial in each of the two basins.     

Dams,Floodplain Land Use,and Riparian Forest Conservation in the Semiarid Upper Colorado River Basin,USA

Land and water resource development can independently eliminate riparian plant communities, including Fremont cottonwood forest (CF), a major contributor to ecosystem structure and functioning in semiarid portions of the American Southwest. We tested whether floodplain development was linked to river regulation in the Upper Colorado River Basin (UCRB) by relating the extent of five developed land-cover categories as well as CF and other natural vegetation to catchment reservoir capacity, changes in total annual and annual peak discharge, and overall level of mainstem hydrologic alteration (small, moderate, or large) in 26 fourth-order subbasins. We also asked whether CF appeared to be in jeopardy at a regional level. We classified 51% of the 57,000 ha of alluvial floodplain examined along >2600 km of mainstem rivers as CF and 36% as developed. The proportion developed was unrelated to the level of mainstem hydrologic alteration. The proportion classified as CF was also independent of the level of hydrologic alteration, a result we attribute to confounding effects from development, the presence of time lags, and contrasting effects from flow alteration in different subbasins. Most CF (68% by area) had a sparse canopy (50% canopy cover occupied <1% of the floodplain in 15 subbasins. We suggest that CF extent in the UCRB will decline markedly in the future, when the old trees on floodplains now disconnected from the river die and large areas change from CF to non-CF categories. Attention at a basinwide scale to the multiple factors affecting cottonwood patch dynamics is needed to assure conservation of these riparian forests.     

DIN Retention‐Transport Through Four Hydrologically Connected Zones in a Headwater Catchment of the Upper Mississippi River1

Abstract: Dissolved inorganic nitrogen (DIN) retention‐transport through a headwater catchment was synthesized from studies encompassing four distinct hydrologic zones of the Shingobee River Headwaters near the origin of the Mississippi River. The hydrologic zones included: (1) hillslope ground water (ridge to bankside riparian); (2) alluvial riparian ground water; (3) ground water discharged through subchannel sediments (hyporheic zone); and (4) channel surface water. During subsurface hillslope transport through Zone 1, DIN, primarily nitrate, decreased from ～3 mg‐N/l to <0.1 mg‐N/l. Ambient seasonal nitrate:chloride ratios in hillslope flow paths indicated both dilution and biotic processing caused nitrate loss. Biologically available organic carbon controlled biotic nitrate retention during hillslope transport. In the alluvial riparian zone (Zone 2) biologically available organic carbon controlled nitrate depletion although processing of both ambient and amended nitrate was faster during the summer than winter. In the hyporheic zone (Zone 3) and stream surface water (Zone 4) DIN retention was primarily controlled by temperature. Perfusion core studies using hyporheic sediment indicated sufficient organic carbon in bed sediments to retain ground water DIN via coupled nitrification‐denitrification. Numerical simulations of seasonal hyporheic sediment nitrification‐denitrification rates from perfusion cores adequately predicted surface water ammonium but not nitrate when compared to 5 years of monthly field data (1989‐93). Mass balance studies in stream surface water indicated proportionally higher summer than winter N retention. Watershed DIN retention was effective during summer under the current land use of intermittently grazed pasture. However, more intensive land use such as row crop agriculture would decrease nitrate retention efficiency and increase loads to surface water. Understanding DIN retention capacity throughout the system, including special channel features such as sloughs, wetlands and floodplains that provide surface water‐ground water connectivity, will be required to develop effective nitrate management strategies.     

INFLUENCE OF TWO WOODY RIPARIAN SPECIES ON CRITICAL CONDITIONS FOR STREAMBANK STABILITY: UPPER TRUCKEE RIVER,CALIFORNIA1

Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine grained sediment emanating from upland and channel erosion. A recent study showed that the Upper Truckee River is the single largest contributor of sediment to Lake Tahoe, with a large proportion of the sediment load emanating from streambanks. This study combines field data with numerical modeling to identify the critical conditions for bank stability along an unstable reach of the Upper Truckee River, California. Bank failures occur during winter and spring months, brought on by repeated basal melting of snow packs and rain‐on‐snow events. Field studies of young lodgepole pines and Lemmon's willow were used to quantify the mechanical, hydrologic, and net effects of riparian vegetation on streambank stability. Lemmon's willow provided an order of magnitude more root reinforcement (5.5 kPa) than the lodgepole pines (0.5 kPa); the hydrologic effects of the species varied spatially and temporally and generally were of a smaller magnitude than the mechanical effects. Overall, Lemmon's willow provided a significant increase in bank strength, reducing the frequency of bank failures and delivery of fine grained sediment to the study reach of the Upper Truckee River.     

Basic hydrologic studies for assessing impacts of flow diversions on riparian vegetation: Examples from streams of the eastern Sierra Nevada,California, USA

As the number of proposals to divert streamflow for power production has increased in recent years, interest has grown in predicting the impacts of flow reductions on riparian vegetation. Because the extent and density of riparian vegetation depend largely on local geomorphic and hydrologic setting, site-specific geomorphic and hydrologic information is needed. This article describes methods for collecting relevant hydrologic data, and reports the results of such studies on seven stream reaches proposed for hydroelectric development in the eastern Sierra Nevada, California, USA. The methods described are: (a) preparing geomorphic maps from aerial photographs, (b) using well level records to evaluate the influence of streamflow on the riparian water table, (c) taking synoptic flow measurements to identify gaining and losing reaches, and (d) analyzing flow records from an upstream-downstream pair of gages to document seasonal variations in downstream flow losses. In the eastern Sierra Nevada, the geomorphic influences on hydrology and riparian vegetation were pronounced. For example, in a large, U-shaped glacial valley, the width of the riparian strip was highly variable along the study reach and was related to geomorphic controls, whereas the study reaches on alluvial fan deposits had relatively uniform geomorphology and riparian strip width. Flow losses of 20% were typical over reaches on alluvial fans. In a mountain valley, however, one stream gained up to 275% from geomorphically controlled groundwater contributions.     

LOW DISCHARGE PERIODS OF RIVERS IN THE UPPER VISTULA RIVER BASIN,POLAND1

ABSTRACT: A method is presented for determining low discharge periods of rivers based on threshold values defined in terms of MEAN OF MINIMUM SUMMER (WINTER) DISCHARGES. The method is used to determine summer low flow periods in the Vistula River basin in Poland. Analysis is based on daily discharge data for 84 basins of the Upper Vistula River which was collected by the Polish Institute of Meteorology and Water Economy.     

Application of the ELOHA Framework to Regulated Rivers in the Upper Tennessee River Basin: A Case Study

In order for habitat restoration in regulated rivers to be effective at large scales, broadly applicable frameworks are needed that provide measurable objectives and contexts for management. The Ecological Limits of Hydrologic Alteration (ELOHA) framework was created as a template to assess hydrologic alterations, develop relationships between altered streamflow and ecology, and establish environmental flow standards. We tested the utility of ELOHA in informing flow restoration applications for fish and riparian communities in regulated rivers in the Upper Tennessee River Basin (UTRB). We followed the steps of ELOHA to generate univariate relationships between altered flows and ecology within the UTRB. By comparison, we constructed multivariate models to determine improvements in predictive capacity with the addition of non-flow variables. We then determined whether those relationships could predict fish and riparian responses to flow restoration in the Cheoah River, a regulated system within the UTRB. Although ELOHA provided a robust template to construct hydrologic information and predict hydrology for ungaged locations, our results do not suggest that univariate relationships between flow and ecology (step 4, ELOHA process) can produce results sufficient to guide flow restoration in regulated rivers. After constructing multivariate models, we successfully developed predictive relationships between flow alterations and fish/riparian responses. In accordance with model predictions, riparian encroachment displayed consistent decreases with increases in flow magnitude in the Cheoah River; however, fish richness did not increase as predicted 4 years after restoration. Our results suggest that altered temperature and substrate and the current disturbance regime may have reduced opportunities for fish species colonization. Our case study highlights the need for interdisciplinary science in defining environmental flows for regulated rivers and the need for adaptive management approaches once flows are restored.     

Riparian vegetation instream flow requirements: A case study from a diverted stream in the Eastern Sierra Nevada,California, USA

A methodology is described that allows determination of instream flow requirements for maintenance of riparian trees. Tree-ring data revealed strong relationships between tree growth and stream flow volume for riparian species at Rush Creek, an alluvial stream within an arid setting; these relationships allowed development of models that predict growth rates from hydrologic variables. The models can be used to assess instream flow requirements under the assumption that certain levels of growth are necessary to maintain the population. There is a critical need for development and use of instream flow methodologies for riparian vegetation, since present methodologies focus on needs of aquatic animals (e.g., fish) and may underestimate needs of the entire riparian ecosystem.     

Evaluating Flow Diversion Impacts to Groundwater‐Dependent Riparian Vegetation with Flow Alteration and Groundwater Model Analysis

An approach for assessing the potential ecologic response of groundwater‐dependent riparian vegetation to flow alteration is developed, focusing on change to groundwater. Groundwater requirements for riparian vegetation are reviewed in conjunction with flow alteration statistics. Where flow alteration coincides with groundwater‐related vegetation sensitivities, scenarios are developed for groundwater simulation. Groundwater depths and recession rates in the riparian zone are simulated for baseline and altered stream hydrographs, with changes to river stage and width represented with a transient, flow‐dependent boundary condition. Potential flow diversion from the Upper Gila River in New Mexico is examined. Statistical flow alteration analysis, applying prospective diversions to a 76‐year record of daily flow, shows that flows in the winter‐spring months and within the high‐pulse to small flood range are subject to greatest potential change. Groundwater simulation scenarios are developed for these flow conditions in representative dry, near‐average, and wet years. Differences in groundwater elevations, generally less than 0.25 m during the flow alteration period, dissipate rapidly following cessation of diversion. Relating groundwater depth, recession rates and range of fluctuations to riparian vegetation needs, we find adverse ecological response is not expected from groundwater impacts for the flow alteration examined.     

Spatial Calibration and Temporal Validation of Flow for Regional Scale Hydrologic Modeling1

Abstract: Physically based regional scale hydrologic modeling is gaining importance for planning and management of water resources. Calibration and validation of such regional scale model is necessary before applying it for scenario assessment. However, in most regional scale hydrologic modeling, flow validation is performed at the river basin outlet without accounting for spatial variations in hydrological parameters within the subunits. In this study, we calibrated the model to capture the spatial variations in runoff at subwatershed level to assure local water balance, and validated the streamflow at key gaging stations along the river to assure temporal variability. Ohio and Arkansas‐White‐Red River Basins of the United States were modeled using Soil and Water Assessment Tool (SWAT) for the period from 1961 to 1990. R² values of average annual runoff at subwatersheds were 0.78 and 0.99 for the Ohio and Arkansas Basins. Observed and simulated annual and monthly streamflow from 1961 to 1990 is used for temporal validation at the gages. R² values estimated were greater than 0.6. In summary, spatially distributed calibration at subwatersheds and temporal validation at the stream gages accounted for the spatial and temporal hydrological patterns reasonably well in the two river basins. This study highlights the importance of spatially distributed calibration and validation in large river basins.     

STORMFLOW SIMULATION USING A GEOGRAPHICAL INFORMATION SYSTEM WITH A DISTRIBUTED APPROACH1

ABSTRACT: With the increasing availability of digital and remotely sensed data such as land use, soil texture, and digital elevation models (DEMs), geographic information systems (GIS) have become an indispensable tool in preprocessing data sets for watershed hydrologic modeling and post processing simulation results. However, model inputs and outputs must be transferred between the model and the GIS. These transfers can be greatly simplified by incorporating the model itself into the GIS environment. To this end, a simple hydrologic model, which incorporates the curve number method of rainfall‐runoff partitioning, the ground‐water base‐flow routine, and the Muskingum flow routing procedure, was implemented on the GIS. The model interfaces directly with stream network, flow direction, and watershed boundary data generated using standard GIS terrain analysis tools; and while the model is running, various data layers may be viewed at each time step using the full display capabilities. The terrain analysis tools were first used to delineate the drainage basins and stream networks for the Susquehanna River. Then the model was used to simulate the hydrologic response of the Upper West Branch of the Susquehanna to two different storms. The simulated streamflow hydrographs compare well with the observed hydrographs at the basin outlet.     

Heterogeneity of Hydrologic Response in Urban Watersheds1

Meierdiercks, Katherine L., James A. Smith, Mary Lynn Baeck, and Andrew J. Miller, 2010. Heterogeneity of Hydrologic Response in Urban Watersheds. Journal of the American Water Resources Association (JAWRA) 46(6):1221–1237. DOI: 10.1111/j.1752-1688.2010.00487.x Abstract: The changing patterns of streamflow associated with urbanization are examined through analyses of discharge and rainfall records for the study watersheds of the Baltimore Ecosystem Study (BES). Analyses utilize a decade (1999-2008) of observations from a dense U.S. Geological Survey stream gaging network and Hydro-NEXRAD radar rainfall fields. The principal study watershed of the BES is Gwynns Falls (171 km²). Focus is given to two Gwynns Falls basins with contrasting patterns and histories of development, Dead Run and Upper Gwynns Falls. The sharp contrasts in streamflow properties between the basins reflect the differences in urban development prior to implementation of stormwater management regulations (much of Dead Run) and development for which stormwater management is an integral part of the hydrologic system (Upper Gwynns Falls). The mean annual runoff in Dead Run (558 mm) is 35% larger than that of Upper Gwynns Falls; larger contrasts in runoff properties typify the “warm season” and are linked to storm event hydrologic response. Spatial heterogeneities in storm event response are reflected in seasonal and diurnal properties of streamflow. Analyses of storm event response are presented for June 2006, during which monthly rainfall over the BES region ranged from less than 150 to more than 500 mm. Baisman Run, the BES forest reference watershed, and Moores Run, a highly urbanized watershed in Baltimore City, provide “end-member” representations of urban impacts on streamflow.     

CHANNEL NETWORK EXTENSION BY LOGGING ROADS IN TWO BASINS,WESTERN CASCADES,OREGON1

ABSTRACT: Based on field surveys and analysis of road networks using a geographic information system (GIS), we assessed the hydrologic integration of an extensive logging-road network with the stream network in two adjacent 62 and 119 km² basins in the western Cascades of Oregon. Detailed surveys of road drainage for 20 percent of the 350 km road network revealed two hydrologic flow paths that link roads to stream channels: roadside ditches draining to streams (35 percent of the 436 culverts examined), and roadside ditches draining to culverts with gullies incised below their outlets (23 percent of culverts). Gully incision is significantly more likely below culverts on steep (< 40 percent) slopes with longer than average contributing ditch length. Fifty-seven percent of the surveyed road length is connected to the stream network by these surface flowpaths, increasing drainage density by 21 to 50 percent, depending on which road segments are assumed to be connected to streams. We propose a conceptual model to describe the hydrologic function of roads based on two effects: (1) a volumetric effect, increasing the volume of water available for quickflow and (2) a timing effect, altering flow-routing efficiency through extensions to the drainage network. This study examines the second of these two effects. Future work must quantify discharge along road segments connected to the stream network in order to more fully explain road impacts on basin hydrology.     

Probabilistic Streamflow Generation Model for Data Sparse Arid Watersheds1

Abstract: The authors present a model that generates streamflow for ephemeral arid streams. The model consists of a stochastic hourly precipitation point process model and a conceptual model that transforms precipitation into flow. It was applied to the Santa Cruz River at the border crossing from Mexico into Southern Arizona. The model was constructed for four different seasons and three categories of inter‐annual variability for the wet seasons of summer and winter. The drainage area is ungauged and precipitation information was inferred from a precipitation gauge downstream. The precipitation gauge record was evaluated against simulated precipitation from a mesoscale numerical weather prediction model, and was found to be the representative of the regional precipitation variability. The flow generation was found to reproduce the variability in the observed record at the daily, seasonal and annual time scales, and it is suitable for use in planning studies for the study site.