The results of a hydrological analysis that was conducted as part of a larger, multifaceted, collaborative effort to quantify ecosystem functions in watersheds subjected to land-use and land-cover change are presented. The primary goal of the study was to determine whether a small watershed in the Appalachian region (USA) that was recently subjected to surface mining and reclamation practices produces stormflow responses to rain events that are different from those produced by a nearby reference watershed covered by young, second-growth forest. Water balances indicated that runoff yields did not vary significantly between the two watersheds on an annual basis. Statistically significant differences (p⩽0·05) in runoff responses were observed on an event basis, however, with the mined/reclaimed watershed producing, on average (a) higher storm runoff coefficients (2·5×), (b) greater total storm runoff (3×), and (c) higher peak hourly runoff rates (2×) when compared with the reference watershed. Results of a unit hydrograph analysis also showed, unexpectedly, that the modelled unit responses of the two watersheds to effective rainfall pulses were similar, despite the noted differences in land cover. Differences in stormflow responses were thus largely explained by dramatic reductions in cumulative rates of rainfall abstraction (measured using infiltrometers) attributable to soil compaction during land reclamation. Additional field hydrological measurements on other mined watersheds will be needed to generalize our results, as well as to understand and predict the cumulative hydrological impacts of widespread surface mining in larger watersheds and river basins. Copyright © 2006 John Wiley & Sons, Ltd.

Comparison of stormflow responses of surface-mined and forested watersheds in the Appalachian Mountains, USA

Early succession aspen and late succession conifer forests have different architecture and physiology affecting hydrologic transfer processes. An evaluation of water pools and fluxes was used to determine differences in the hydrologic dynamics between stands of quaking aspen (Populus tremuloides) and associated stands of mixed conifer consisting of white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), and Engelmann spruce (Picea engelmannii). In 2005 and 2006, measurements of snow water accumulation, snow ablation (melt), soil water content, snowpack sublimation, and evapotranspiration (ET) were measured in adjacent aspen and conifer stands. Peak snow water equivalent (SWE) averaged 34–44% higher in aspen in 2005 (average snow fall) and 2006 (above average snow fall), respectively, whereas snow ablation rates were greater in aspen stands (21 mm day−1) compared to conifer stands (11 mm day−1). When changes in soil water content (due to over-winter snowmelt) were combined with peak snow accumulation in 2006, aspen had greater potential (42–83%) water yield for runoff and groundwater recharge. Snowpack sublimation during the ablation period was not significantly different between meadow, aspen, and conifer sites and comprised less than 5% of the winter precipitation. Extended conifer transpiration in spring and fall did not contribute to large differences in water yield (<28 mm y−1). Summertime ET rates were higher in aspen plots (3.6 mm day−1) than in conifer plots (2.7 mm day−1), and differences in net ET largely reflected soil column porosity. This study shows that the largest differences in annual water yield between aspen and conifer stands result from differences in SWE and net summertime ET. Although SWE and accumulation of water in soil was greater in aspen, it was partly offset by greater net annual ET losses in aspen.

Differential Snowpack Accumulation and Water Dynamics in Aspen and Conifer Communities: Implications for Water Yield and Ecosystem Function

Aspen is considered a keystone species, and aspen communities are critical for maintaining biodiversity in western landscapes Inventories of aspen stand health across the Eagle Lake Ranger District (ELRD), Lassen National Forest, California, USA, indicate that 77% of stands are in decline and at risk of loss as defined by almost complete loss of mature aspen with little or no regeneration This decline is due to competition from conifers establishing within aspen stands as a result of modification of natural fire regimes coupled with excessive browsing by livestock Restoration treatments were implemented in four aspen stands in 1999 using mechanical equipment to remove competing conifers to enhance the growth environment for aspen Recruitment and establishment of aspen stems were measured in treated stands (removal of competing conifers) and non-treated stands (control) immediately prior to treatment and 2 and 4 years post-treatment There was a significant increase in total aspen stem density and in two of three aspen regeneration size classes for treated stands compared to controls Pre-treatment total aspen density was positively associated with total aspen density and density in all size classes of aspen (p < 0001) The results demonstrate that mechanical removal of conifers is an effective treatment for restoring aspen

http://rangelandwatersheds.ucdavis.edu/publication list and files/jones aspen paper restoration ecology 2005.pdf

Removal of Encroaching Conifers to Regenerate Degraded Aspen Stands in the Sierra Nevada

Streamflow changes resulting from clearcut harvest of lodgepole pine (Pinus contorta) on a 2145 hectare drainage basin are evaluated by the paired watershed technique. Thirty years of continuous daily streamflow records were used in the analysis, including 10 pre-harvest and 20 post-harvest years of data. Regression analysis was used to estimate the effects of timber harvest on annual water yield and annual peak discharge. Removal of 14 million board feet of lodgepole pine (Pinus contorta) from about 526 hectares (25 percent of the basin) produced an average of 14.7 cm additional water yield per year, or an increase of 52 percent. Mean annual daily maximum discharge also increased by 1.6 cubic meters per second or 66 percent. Increases occurred primarily during the period of May through August with little or no change in wintertime streamflows. Results suggest that clearcutting conifers in relatively large watersheds (> 2000 ha) may produce significant increases in water yield and flooding. Implications of altered streamflow regimes are important for assessing the future ecological integrity of stream ecosystems subject to large-scale timber harvest and other disturbances that remove a substantial proportion of the forest cover.

Effects of basin‐scale timber harvest on water yield and peak streamflow

This document provides managers with a literature synthesis of the historical conditions, current conditions, fire regime condition classes (FRCC), and recommended treatments for the major ecosystems in southern Utah. Sections are by ecosystems and include: 1) coniferous forests (ponderosa pine, mixed conifer, and Engelmann spruce-subalpine fir), 2) aspen, 3) pinyon-juniper, 4) big and black sagebrush, and 5) desert shrubs (creosotebush, blackbrush, and interior chaparral). Southern Utah is at the ecological crossroads for much of the western United States. It contains steep environmental gradients and a broad range of fuels and fire regimes associated with vegetation types representative of the Rocky Mountains, the Great Basin, Northern Arizona and New Mexico, and the Mohave Desert. The Southern Utah Demonstration Area consists of contiguous state and federal lands within the administrative boundaries of the Bureau of Land Management (BLM), Fishlake and Dixie National Forests, National Park Sevice, and State of Utah, roughly encompassing the southern 15 percent of Utah (3.24 million ha). The vegetation types described are similar in species composition, stand structure, and ecologic function, including fire regime to vegetation types found on hundreds of millions of hectares in the 11 western states.

Fire Ecology and Management of the Major Ecosystems of Southern Utah

Heat pulse velocity techniques were developed for effective monitoring of water movement in aspen (Populus tremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (Picea engelmannif). Water loss was monitored in replicated trees of each species for one year. These data were used to modify the plant activity index (a reflection of the ability of plants to transpire water at various times during a year) and the crop coefficient (a reflection of differences in consumptive use rates of water by different vegetation types when all other factors are held constant) for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling in dicate 18.6 cm net loss of moisture available for streamflow when spruce replaced aspen, and a loss of 7.2 cm when fir forests replaced aspen. The aspen to conifer successional trend appears, therefore, to be significantly reducing water yields in the western United States.

A preliminary quantification of the impacts of aspen to conifer succession on water yield. II. Modeling results

Twenty-six aspen (Populus tremuloides Michx.), 20 subalpine fir (Abies lasiocarps (Hook.) Nutt.), and 20 Engelmann spruce (Pices engelmanil (Parry) Engelm.) of various sizes were cut under water and suspended in permanent reserviors at a northern Utah site. The reservoirs were asealed so that all water loss was due to consumption by the trees. Sap velocities, as computed from heat pulse velocities, were related to conducting areas of the tree trunks. Computed transpiration volumes were then correlated with actual water losses from the reservoirs. Coefficients of determination (R2) of 0.87, 0.86, and 0.82 were obtained for the fir, aspen, and sprucs, respectively. Reservoir water loss for each species for each season was then used to adjust a plant activity index for computing transpiration within ASPCON, a model describing the hydrology of aspen to conifer succession. The plant activity index reflects the variation in the capability of a plant community to transpire water over the year. Assumptions and limitations of the heat pulse velocity technique are also outlined.

A preliminary quantification of the impacts of aspen to conifer succession on water yield. I. Heat pulse methodology for model calibration

Heat pulse velocity techniques were developed for effectively monitoring water movement in aspen (Populus ttremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (picea engelmannii). Once the techniques were perfected, transpiration was monitored in replicated trees of each species for one year. This data was used to modify the plant activity index and the crop coefficient for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling indicate 18.5 cm (7.3 in) net loss of moisture available for streamflow when spruce replace aspen, and a loss of 7.1 cm (2.8 in) when fir forests cover the watershed. The aspen to conifer successional trend is therefore significantly reducing water yields within the Colorado River Basin, water that could be used to dilute salt downstream from the high water-yielding watersheds.

/pdf/a-preliminary-quantification-of-the-impacts-of-aspen-to-58rqvz181r.pdf

A Preliminary Quantification of the Impacts of Aspen to Conifer Succession on Water Yield Within the Colorado River Basin (A Process Aggravating the Salt Pollution Problem)

A diversion system has been designed to carry the flow from East Fork of Coal Creek around the area proposed for mining at Thunder Basin Coal Company's (TBCC) Coal Creek mine in Campbell County, Wyoming. This paper describes the field and analysis procedures necessary to prepare the diversion design and impact evaluation, and the innovative concepts developed for the diversion system design to minimize impacts on downstream channel stability. Under the proposed diversion system design, water from the East Basin of Coal Creek will be diverted at two locations. At one location, flow will be impounded by a small dam and decanted by a pump through a pipeline into East Fork at the location of the second diversion. At this location, a training dike will be placed across the stream channel to divert flows into a diversion channel. Gravity flow along the diversion channel will deliver water to a playa area which will be converted into a detention basin by placing a small dam across its southern end. Flows up to the magnitude of the 24-hour 2-year peak flow will be passed directly through the detention basin into Middle Fork with negligible attenuation of flow rates. For less frequent events,more » water will be stored in the detention basin in order to prevent velocities in Lower Middle Fork from exceeding the maximum permissible velocity above which scouring may occur. Evaporation and seepage losses from the diversion system were estimated to be small and should be more than offset by the addition of water from the playa drainage basin into the Coal Creek drainage. Velocities predicted for the Lower Middle Fork after the diversion is constructed are expected to be low enough that significant erosion of the channel is not expected to occur.« less

Design and impact analysis for diversion at Coal Creek mine

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A preliminary quantification of the impacts of aspen to conifer succession on water yield. II. Modeling results

A preliminary quantification of the impacts of aspen to conifer succession on water yield. I. Heat pulse methodology for model calibration

A Preliminary Quantification of the Impacts of Aspen to Conifer Succession on Water Yield Within the Colorado River Basin (A Process Aggravating the Salt Pollution Problem)

Design and impact analysis for diversion at Coal Creek mine