Richard C. Warner

Water quality characteristics of discharge from reforested loose-dumped mine spoil in eastern Kentucky.

Surface mining is a common method for extracting coal in the coal fields of eastern Kentucky. Using the Forestry Reclamation Approach (FRA), which emphasizes the use of minimally compacted or loose-dumped spoil as a growth medium for trees, reclamation practitioners are successfully reestablishing forests. Yet, questions remain regarding the effects FRA has on the quality of waters discharged to receiving streams. To examine the effect of FRA on water quality, this study compared waters that were discharged from three types of spoils: predominantly brown, weathered sandstone (BROWN); predominantly gray, unweathered sandstone (GRAY); and an equal mixture of both aforementioned sandstones and shale (MIXED). The water quality parameters pH, EC, Ca, K, Mg, Na, NO-N, NH-N, SO, Cl, TC, suspended sediment concentration (SSC), settleable solids (SS), and turbidity were monitored over a 2-yr period on six 0.4-ha plots (two replications per spoil type). Generally, levels of Cl, SO, Ca, NO-N, NH-N, SS, SSC, and turbidity decreased over time. The pH for all spoils increased from about 7.5 to 8.5. The EC remained relatively level in the BROWN spoil, whereas the GRAY and MIXED spoils had downward trajectories that were approaching 500 μS cm. The value of 500 μS cm has been reported as the apparent threshold at which certain taxa such as Ephemeroptera (e.g., Mayfly) recolonize disturbed headwater streams of eastern Kentucky and adjacent coal-producing Appalachian states.

EVAPORATION REDUCTION POTENTIAL IN AN UNDISTURBED SOIL IRRIGATED WITH SURFACE DRIP AND SAND TUBE IRRIGATION

The efficiency of drip irrigation is highly dependent on evaporation losses occurring from the constantly saturated soil beneath emitters. Advent of subsurface drip irrigation is in part an approach to curb this inefficiency. An irrigation method, Sand Tube Irrigation (STI), is proposed to increase the efficiency of “Normal” surface applied drip Irrigation (NI method) on permanent tree crops without the need for burying the irrigation tubing. The sand tube consists of removing a soil core beneath the emitter and filling the void with coarse sand. A weighing lysimeter was constructed in the laboratory and instrumented to directly measure temporal evaporation from large, undisturbed soil columns, 0.7 m in diameter and 0.8 m in height. Experiments were performed on six replicated soil monoliths to compare the two methods. The results indicated that, for four consecutive days after irrigation, there was a significant difference at the 95% confidence level between evaporation occurring from the NI and STI methods. After four days of evaporation, comparison of water contents indicated that a higher amount of water existed between the depths of 0.2 to 0.55 m in the STI versus the NI method. Although drainage occurred from the macropore structure of the undisturbed soil monoliths, the STI method showed potential in retaining more water in the micropore structure of the lower depths, that would be available for plant use rather than potential evaporation.

Runoff curve numbers for loose-dumped spoil in the Cumberland Plateau of eastern Kentucky

Excess compaction occurs through the use of traditional surface mining reclamation techniques, resulting in low infiltration rates and subsequently high peak flows and runoff volumes. The incorporation of loose-dumped spoil into the reclamation process has been shown to promote tree growth; however, designers have little information regarding the probable hydrologic consequences (PHC) associated with this spoil disposal method. To better understand the hydrologic effects of reclaiming mined lands using loose-dumped spoil, curve numbers (CN) were developed for both a steeply sloping, forested watershed in eastern Kentucky and six, 0.4 ha test cells comprised of three types of loose-dumped spoil: (1) brown, weathered sandstone, (2) grey, unweathered sandstone and (3) a mixture of both sandstones and shale. The spoil was placed in accordance with the Forestry Reclamation Approach (FRA). Results of this project indicate that the mean CN for loose-dumped spoil was equivalent to the mean CN for the forested watershed.

FOREST ESTABLISHMENT AND WATER QUALITY CHARACTERISTICS AS INFLUENCED BY SPOIL TYPE ON A LOOSE- GRADED SURFACE MINE IN EASTERN KENTUCKY

Six research plots were established on a surface mine for the purpose of evaluating the forest productivity potential and hydrological and water quality characteristics of three different loose-graded spoil types. The three spoil types were: (1) predominately brown, weathered sandstone (BROWN); (2) predominately gray, un-weathered sandstone (GRAY); and (3) mixed weathered and un-weathered sandstones and shale material (MIXED). The average area of the six plots was approximately 3,658 m 2 . The physical and chemical soil characteristics that gave the BROWN spoil type a predictably higher productivity potential and natural regeneration than the GRAY and MIXED spoil were its finer soil texture, higher CEC and P concentration, and a pH that was more suitable for native hardwood trees. Four species of tree seedlings were planted into the spoils. Growth and survival of the planted trees were evaluated for three years. As an indicator of natural succession potential, percentage ground cover of volunteer vegetation on the three spoil types was also evaluated. By the third year (2007) after planting, the BROWN spoil type had a significantly higher average tree volume index than the MIXED spoil and MIXED was significantly higher than GRAY. Ground cover from natural regeneration was found to be 66.4% on the BROWN spoil (61 different species), 5.8% on the MIXED spoil (35 different species), and less than 2.0% on the GRAY spoil (12 different species). Results showed that the loose-graded spoil in this experiment was characterized by low discharge volumes, small peak discharges, and long durations of discharge and had hydrologic characteristics of a forested watershed, even at this early stage of development. Generally, concentrations of Ca, Mg, and SO4 2- decreased over time in GRAY and MIXED and increased in BROWN. The pH of the water discharge from all three spoil types has increased from about 7.5 to 8.5. Although the average electrical conductivity (EC) in water discharged from the BROWN spoil remained relatively level during the study period, the GRAY and MIXED appears to be on a downward trajectory from about 1500 µS cm -1 to about 500 µS cm -1 . The latter value of EC has been reported as the apparent threshold at which the benthic invertebrate community returns to drastically disturbed headwater streams of eastern Kentucky and adjacent coal-producing Appalachian states.

SURFACE MINE REFORESTATION RESEARCH: EVALUATION OF TREE RESPONSE TO LOW COMPACTION RECLAMATION TECHNIQUES 1

In 1996, a multidisciplinary group of researchers at the University of Kentucky initiated a study on the Starfire surface mine in eastern Kentucky to evaluate the effects of soil compaction and two organic amendments on the survivability and growth of high value tree species. Three types of prepared rooting medium were examined: compacted spoil, lightly compacted spoil, and uncompacted spoil. The compacted spoil was prepared using normally accepted spoil handling techniques that resulted in a smooth graded surface. The lightly compacted spoil was loose-dumped and struck-off with one or two passes of a bulldozer. The uncompacted spoil was loose-dumped and not further disturbed. In addition, organic amendments (mulches) were evaluated within the three reclamation techniques. The organic amendments used were processed hardwood bark mulch and a combination of straw and horse manure mulch. The following six species of trees were planted: white oak (Quercus alba), white ash (Fraxinus americana), eastern white pine (Pinus strobus), northern red oak (Quercus rubra), black walnut (Juglans nigra), and yellow poplar (Liriodendron tulipifera). Five of the six species, the exception being white ash, showed increased survivability as compaction was minimized. Additionally, the loose-graded techniques led to enhanced growth in height for the seedlings. The addition of organic amendments also showed additional benefit but results varied by species and by treatment. Results definitively show that strike-off and loose-dump techniques improve seedling height and survival. The data also suggest that even a small amount of traffic (i.e., one or two passes per the strike-off method) may result in enough compaction to significantly reduce survival and growth in some species, such as yellow poplar and white pine. In the backfilling and grading process, spoil material should be placed and compacted according to standard engineering practices so that the required stability and approximate original contour is achieved. However, the top 1.2 to 1.8 meters (4 to 6 feet) of material should not be graded or only lightly graded so that it is as uncompacted as possible.

MODELING SURFACE AND SUBSURFACE PESTICIDE TRANSPORT UNDER THREE FIELD CONDITIONS USING PRZM-3 AND GLEAMS

Contaminant transport models should be evaluated over a wide range of conditions to determine their limitations. The models PRZM and GLEAMS have been evaluated many times, but few studies are available in which predicted movement in runoff and percolate were simultaneously evaluated against field data. Studies of this type are essential because pesticide leaching and runoff are mutually dependent processes. For this reason, PRZM-3 and GLEAMS were evaluated for their ability to predict metribuzin concentrations in runoff, sediment, subsurface soil, and pan lysimeters under three field conditions (yard waste compost amended, no-till, and conventional-till) on a Lowell silt loam soil. Sensitive input parameters were either site specific (climatic, soil, and chemical) or calibrated (K-factor, C-factor, curve number). In general, both models under-predicted metribuzin concentration in runoff water, runoff sediment, subplow layer soil (15-75 cm), and pan lysimeter water (75 cm). Contrary to field data, both models predicted that a large percentage (> 50%) of metribuzin would move below the “mixing zone” (top 1 cm) during the first rainfall event after application. Relatively little metribuzin was predicted to move beyond the plow layer (top 15 cm) into the pan lysimeters or subsurface soil throughout the simulation period, possibly due to the lack of a macropore component in the models. High metribuzin concentrations in sediment (field data) indicated that relatively little metribuzin moved below the “mixing zone”, possibly because of hysteresis but much of the metribuzin that did move was quickly transported into the pan lysimeters, probably due to macropore flow. GLEAMS more accurately predicted pesticide concentration in sediment and PRZM predicted subsurface soil concentration somewhat more accurately than GLEAMS. Little difference in accuracy was detected between models on metribuzin concentration in runoff or metribuzin concentration in percolate. Although both models generally under-predicted metribuzin concentration in runoff, runoff transport (mass of metribuzin in runoff) for the study period was over-predicted by both models which emphasizes the importance of accurately predicting herbicide concentration and runoff volume soon after application when the surface pesticide concentrations are highest.

Comparison of water and temperature distribution profiles under sand tube irrigation

Drip irrigation is one of the most efficient systems in delivering water to the plant root zone. Research has shown that the saturated, or nearly saturated, surface beneath the emitter may increase evaporation thereby reducing the irrigation efficiency. To increase the efficiency of surface applied drip irrigation on permanent tree crops a sand tube irrigation (STI) method was developed and tested. The sand tube method consists of removing a soil core beneath the emitter and filling the void with coarse sand. A weighing lysimeter was designed and instrumented to directly measure temporal evaporation during irrigation and for a period of three days after irrigation ceased. Thermocouples were used throughout the soil profile to detect the temperature variation and also to determine temporal movement of the wetting front. The results indicated that for the surface applied drip irrigation method, approximately 30% of the applied water evaporated during the four-day period after irrigation. The STI method resulted in approximately 4% of the applied water being evaporated. The STI method allowed more water to remain in the soil profile thereby increasing the irrigation efficiency.

The Relationship Between Soil Water Potential, Environmental Factors, and Plant Moisture Status for Poblano Pepper Grown Using Tensiometer-Scheduled Irrigation

Managing irrigation using soil moisture sensors for automation can allow for a reduction in water use while avoiding drought stress and maintaining optimum yields in high-value crops. Measurements of plant water status such as leaf water potential and relative water content are often utilized to demonstrate the presence or lack of drought stress in plants subjected to varying soil moisture regimes. Poblano peppers (Capsicum annuum L.) were grown under four automated, tensiometer-controlled irrigation regimes with set points of on/off −30/−25, −40/−35, −50/−45, and −60/−55 kPa and a manually operated treatment with set points of −50/−10 kPa. Soil moisture data were collected at depths of 15 and 25 cm and plant midday leaf water potential and relative water content data were collected throughout the growing season. Yield and fruit quality were unaffected by irrigation treatment. Soil water potential was poorly correlated with plant leaf water potential and relative water content. Plant leaf water potential and relative water content were well correlated with the following environmental factors: air temperature, relative humidity, dew point temperature, and solar radiation. These data indicate that in a non-drought-stressed production system leaf water potential and relative water content may be poor indicators of soil water status because they may be affected by environmental variables to a greater extent than by soil moisture.

Using GIS to Delineate Headwater Stream Origins in the Appalachian Coalfields of Kentucky

Headwater streams have a significant nexus or physical, chemical, and/or biological connection to downstream reaches. Generally, defined as 1st-3rd order with ephemeral, intermittent, or perennial flow regimes, these streams account for a substantial portion of the total stream network particularly in mountainous terrain. Due to their often remote locations, small size, and large numbers, conducting field inventories of headwater streams is challenging. A means of estimating headwater stream location and extent according to flow regime type using publicly available spatial data is needed to simplify this complex process. Using field-collected headwater point of origin data from three control watersheds, streams were characterized according to a set of spatial parameters related to topography, geology, and soils. These parameters were (1) compared to field-collected point of origin data listed in three nearby Jurisdictional Determinations, (2) used to develop a geographic information system (GIS)-based stream network for identifying ephemeral, intermittent, and perennial streams, and (3) applied to a larger watershed and compared to values obtained using the high-resolution National Hydrography Dataset (NHD). The parameters drainage area and local valley slope were the most reliable predictors of flow regime type. Results showed the high-resolution NHD identified no ephemeral streams and 9 and 65% fewer intermittent and perennial streams, respectively, than the GIS model.

Specific conductivity sensor performance: I. Laboratory evaluation

The focus on specific conductivity in the Central Appalachian Coal Fields of the USA has highlighted the need to obtain accurate specific conductivity measurements, particularly in light of the US Environmental Protection Agency (USEPA) guidance that water discharged from mine sites in this region should have specific conductance levels less than 300–500 μS cm−1. Being able to accurately determine the specific conductance levels of mine discharged waters has significant implications for the USEPA as well as mine operators particularly when specific conductance levels approach this designated threshold. Presently, a number of sensors are available on the market for recording specific conductance measurements; however, a detailed study comparing sensor performance under controlled conditions (e.g. temperature and specific conductance levels) has not been performed. This paper compares the performance of four commonly used sensors YSI 6600 V2-4 data sonde, HOBO U-24-001, Solinst Model 3001 LTC Levelogger Junior, and In-situ Aqua TROLL 100. Results of this laboratory study indicated that for conditions more frequently encountered in Kentucky streams, the HOBO and Solinst sensors were most accurate.