ItemMEASURING PORE WATER VELOCITIES AND DYNAMIC CONTACT ANGLES AT UNSTABLE WETTING FRONTS- SUPPLEMENTAL VIDEO FILESNaaran Brindt (2024)The imbibition of fluids in porous media has been studied widely. Still, processes of preferential flow under gravity due to instability at the wetting front, crucial in groundwater contamination, have yet to be fully understood. Recent theories using dynamic contact angles could describe unstable flow phenomena but have not been proven experimentally. Therefore, infiltration experiments in small sand-filled chambers were conducted to explore the effect of dynamic contact angles. A high-speed camera recorded pore invasion at the unstable imbibition liquid front. Since water moves in a plain in the 2-D finger experiment, the camera can be used to measure the velocity of water. However, the hydrophobic front and back walls possibly altered the flow dynamics. Therefore, these two additional 3-D experiment runs (Run III and IV) were performed to compare the wetting front advancement characteristics in 2-D and 3-D. Specifically, we investigated in 3-D whether the wetting front is discontinuous and water advances one pore at a time, which are the required conditions for the Hofmann-Baver equation. ItemVideo recordings for pore water velocities and dynamic contact angle measurements for unstable infiltration fronts in dry sandBrindt, Naaran; Yan, Jiuzhou; Min, Xinying; Jung, Sunghwan; Parlange, Jean-Yves; Steenhuis, Tammo (2023)These files are compressed high-speed video recordings of unstable infiltration runs to dry sand. Compression standard used was H.264. Video files were recorded at 500 fps and condensed to AVI H.264 format at 30 fps. ItemPore-Scale Phenomena of Gravity-Driven Unstable Flow - supplemental video filesMin, Xinying (2023-08-01)Understanding gravity-driven preferential flow in uniform porous materials is important as they can facilitate the movement of pollutants, pathogens, and pesticides to groundwater. Previous studies suggested the dynamic contact angle could be used to model unstable gravity-driven flow in coarse sand. This study aimed to examine this theory in a broader context involving a range of porous media with different static contact angles. The results show that pore water movement was discontinuous. After a period in which the pressure in the water increased, the water moved through the smallest pore with high velocity. After the initial breakthrough, the flow stopped within 0.01 seconds. The relationship between the dynamic contact angle followed the Hoffman-Jiang equation for media that exhibited unstable gravity drive flows. The acid-washed sand that only under very dry conditions had an unstable wetting front did not show a relationship between velocity and contact angle. ItemExperimental data for: Topography Impacts Hydrology in the Sub-Humid Ethiopian HighlandsMhiret, Demesew; Dersseh, Minychl; Guzman, Christian; Dagnew, Dessalegn; Abebe, Wubneh; Zaitchik, Benjamin; Steenhuis, Tammo (2022)(Abstract from full manuscript in Water vol 14, January 2022) Understanding the relationship between topography, hydrological processes, and runoff source areas is essential in engineering design, such as predicting floods and implementing effective watershed management practices. This relationship is not well defined in the highlands with a monsoon climate and needs further study. The objective of this study is to relate topographic position and hydrological response in tropical highlands. The research was conducted in the Debre Mawi watershed in the northwest sub-humid Ethiopian highlands. In the monsoon rain phase of 2017 and 2018, groundwater depth, infiltration rate, and surface runoff were monitored at the upslope, midslope, and downslope positions. Surface runoff rates were measured in farmer fields through distributed V-notch weirs as estimates of positional runoff. Average water table depths were 30 cm deep in the downslope regions and 95 cm in the upslope position. The water table depth affected the steady-state infiltration rate in the rain phase. It was high upslope (350 mm/hr), low midslope (49 mm/hr), and zero downslope. In 2017, the average runoff coefficients were 0.29 for the upslope and midslope and 0.73 downslope. Thus, topographic position affects all aspects of the watershed hydrology in the sub-humid highlands and is critical in determining runoff response. ItemBathymetric survey of Lake Tana, EthiopiaKebedew, Mebrahtom; Kibret, Aron; Tilahun, Seifu; Belete, Mulugeta; Zemale, Fasikaw; Steenhuis, Tammo (2020-07-02)(Abstract from related journal paper prepared in cooperation with Cornell University, BEE Soil and Water Lab) Lakes hold most of the world’s freshwater resources. Safeguarding these resources from water quality degradation requires knowledge of the relationship of lake morphometry and water quality. The 3000-km2 Lake Tana in Ethiopia is one of the water resources where the water quality is decreasing, and water hyacinths have invaded. The objective of this study is to understand the lake morphometry and water quality and specifically the phosphorus dynamics and its effect on the water hyacinths. A bathymetric survey was conducted in late 2017. Various morphometric parameters were derived and both these parameters and sediment available phosphorus were regressed with the dissolved phosphorus. The results show that with a wave base depth nearly equal to maximum depth of 14.8 m, the bottom sediments were continuously suspended in the water column. As a result of the mixing, the dissolved phosphorus in the water column decreased with lake depth and increased with sediment available phosphorus (R2 = 0.84) in the northern half and only 0.45 in the south due to the large flows of Gilgel Abay. Water hyacinths were found where the lake was shallow and the available phosphorus was elevated. The large reservoir of sediment phosphorus will slow down the water hyacinth growth after the lake phosphorus input is reduced. ItemWater Quality Parameters at Small Tributaries to Owasco Lake for 2016-2018Lisboa, Maria Sol; Foley, Jillian; Walter, M. Todd (2020) ItemSupplemental information from: Antecedent and Post-Application Rain Events Trigger Glyphosate Transport from Runoff-Prone SoilsPacenka, Steven (2018-03-31)(Authors and Abstract from a related journal paper of similar title: Brian K. Richards, Steven Pacenka, Michael T. Meyer, Julie E. Dietze, Anna L. Schatz, Karin Teuffer, Ludmilla Aristilde, Tammo S. Steenhuis - all were with Cornell University during 2017 except Meyer and Dietze with US Geological Survey, Organic Geochemistry Research Laboratory, Lawrence, Kansas) Recent environmental surveys report widespread detections of the herbicide glyphosate [N-(phosphonomethyl)glycine] in surface waters, despite its strong immobilization and rapid biodegradation in soils. We carried out four sampling campaigns (during 2015 to 2017) following controlled spray applications on an experimental perennial grass field site with wetness-prone marginal soils. We monitored dissolved glyphosate concentrations in the outflow (runoff and shallow drainage) using liquid chromatography-mass spectrometry and enzyme-linked immunosorbent assays. Rainfall-triggered outflow events occurred between 3 and 13 days following spray application. Outflow concentrations varied widely from 0.01 µg L-1 up to 90 µg L-1, peaking during the first significant outflow event in each campaign and diminishing as flows subsided. Subsequent outflow peaks caused concentrations to again rise but to a lesser extent. Cumulative mass efflux in outflow ranged among campaigns from 0.06 to 1.0 percent of applied glyphosate. Cumulative glyphosate losses in outflow were not associated with total rainfall during the post-spray sampling period but rather with soil hydrologic conditions at the time of spraying as reflected by the 7-day cumulative pre-spray rainfall, with wetter antecedent conditions favoring greater cumulative mobilization. Avoiding spraying under such conditions may mitigate potential glyphosate mobilization. ItemData from: Recharge and groundwater use in the North China Plain for six irrigated crops for an eleven year periodYang, Xiaolin; Sui, Peng; Chen, Yuanquan; Gao, Wangsheng (2014-09-03)(Related journal paper prepared in cooperation with Cornell University, BEE Soil and Water Lab. Paper abstract follows.) Water tables are dropping by approximately one meter annually throughout the North China Plain mainly due to water withdrawals for irrigating winter wheat year after year. In order to examine whether the drawdown can be reduced we calculate the net water use for an 11 year field experiments from 2003 to 2013 where six irrigated crops (winter wheat, summer maize, cotton, peanuts, sweet potato, ryegrass) were grown in different crop rotations in the North China Plain. As part of this experiment moisture contents were measured each at 20 cm intervals in the top 1.8 m. Recharge and net water use were calculated based on these moisture measurement. Results showed that winter wheat and ryegrass had the least recharge with an average of 27mm/year and 39 mm/year, respectively; cotton had the most recharge with an average of 211 mm/year) followed by peanuts with 118 mm/year, sweet potato with 76 mm/year, and summer maize with 44 mm/year. Recharge depended on the amount of irrigation water pumped from the aquifer and therefore a poor indicators of future groundwater decline. Instead net water use (recharge minus irrigation) was found to be good indicator for the decline of the water table. The smallest amount of net (ground water) used was cotton with an average of 14 mm/year, followed by peanut with 32 mm/year, summer maize with 71 mm/year, sweet potato with 74 mm/year. Winter wheat and ryegrass had the greatest net water use with the average of 198 mm/year and 111 mm/year, respectively. Our calculations showed that any single crop would use less water than the prevalent winter maize summer wheat rotation. This growing one crop instead of two will reduce the decline of groundwater and in some rain rich years increase the ground water level, but will result in less income for the farmers. ItemStream Discharge from Harford, NYBarclay, Janet Rice (2013-10-03)This data set contains stream gauge data from Harford, NY during the period of June 18, 2012 to May 20, 2013. Stream depth was measured at 10 minute intervals with an Odyssey Capacitance Water Level Logger. The stream stage was converted to discharge rates with a rating curve that was generated by correlating stage against periodic wading-rod stream discharge measurements 10 using a Marsh-McBirney Flo-Mate Model 2000 portable flowmeter. HF_DailyStreamDischarge.csv gives the average daily discharge, HF_StreamGaugeDepthData.csv gives the stream depth measurements (10 minute intervals), HF_RatingCurve.csv gives the data that was used to generate the rating curve, and SouthBoundary.zip contains the shape file for the watershed. ItemTemperature Logger Data from Cornell’s Teaching and Research FarmBarclay, Janet Rice (2013-10-03)This data set contains data from 3 temperature loggers at the Cornell Teaching and Research Farm in Harford, NY during the period of June 14, 2012 to May 20, 2013. Shallow groundwater temperature (50 cm) was measured with an Odyssey Depth/Temperature logger at Sites A & C. Air temperature was measured at Site C using a Tru-Trak data logger suspended from a tree branch 1.5 m above the ground.