scholarly journals Twentieth-Century Trends in Runoff, Evapotranspiration, and Soil Moisture in the Western United States*

2007 ◽  
Vol 20 (8) ◽  
pp. 1468-1486 ◽  
Author(s):  
Alan F. Hamlet ◽  
Philip W. Mote ◽  
Martyn P. Clark ◽  
Dennis P. Lettenmaier
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Summer Precipitation ◽  
Annual Runoff ◽  
Early Summer ◽  
Western United States ◽  
Spring Precipitation ◽  
Physically Based ◽  
Increasing Trends ◽  
Precipitation Trends

Abstract A physically based hydrology model is used to produce time series for the period 1916–2003 of evapotranspiration (ET), runoff, and soil moisture (SM) over the western United States from which long-term trends are evaluated. The results show that trends in ET in spring and summer are determined primarily by trends in precipitation and snowmelt that determine water availability. From April to June, ET trends are mostly positive due primarily to earlier snowmelt and earlier emergence of snow-free ground, and secondarily to increasing trends in spring precipitation. From July to September trends in ET are more strongly influenced by precipitation trends, with the exception of areas (most notably California) that receive little summer precipitation and have experienced large changes in snowmelt timing. Trends in the seasonal timing of ET are modest, but during the period 1947–2003 when temperature trends are large, they reflect a shift of ET from midsummer to early summer and late spring. As in other studies, it is found that runoff is occurring earlier in spring, a trend that is related primarily to increasing temperature, and is most apparent during 1947–2003. Trends in the annual runoff ratio, a variable critical to western water management, are determined primarily by trends in cool season precipitation, rather than changes in the timing of runoff or ET. It was found that the signature of temperature-related trends in runoff and SM is strongly keyed to mean midwinter [December–February (DJF)] temperatures. Areas with warmer winter temperatures show increasing trends in the runoff fraction as early as February, and colder areas as late as June. Trends toward earlier spring SM recharge are apparent and increasing trends in SM on 1 April are evident over much of the region. The 1 July SM trends are less affected by snowmelt changes and are controlled more by precipitation trends.

scholarly journals Soil storage influences climate–evapotranspiration interactions in three western United States catchments

2015 ◽  
Vol 12 (8) ◽  
pp. 7893-7931
Author(s):  
E. S. Garcia ◽  
C. L. Tague
Keyword(s):  
United States ◽  
Process Model ◽  
Summer Precipitation ◽  
Western United States ◽  
Primary Control ◽  
Influence Model ◽  
Mountainous Catchments ◽  
Precipitation Regimes ◽  
Physically Based ◽  
And Storage

Abstract. In the winter-wet, summer-dry forests of the western United States, total annual evapotranspiration (ET) varies with precipitation and temperature. Geologically mediated drainage and storage properties, however, may strongly influence these relationships between climate and ET. We use a physically based process model to evaluate how soil available water capacity (AWC) and rates of drainage influence model estimates of ET-climate relationships for three snow-dominated, mountainous catchments with differing precipitation regimes. Model estimates show that total annual precipitation is a primary control on inter-annual variation in ET across all catchments and that the timing of recharge is a second order control. Low soil AWC, however, increases the sensitivity of annual ET to these climate drivers by three to five times in our two study basins with drier summers. ET–climate relationships in our Colorado basin receiving summer precipitation are more stable across subsurface drainage and storage characteristics. Climate driver-ET relationships are most sensitive to soil AWC and soil drainage parameters related to lateral redistribution in the relatively dry Sierra site that receives little summer precipitation. Our results demonstrate that uncertainty in geophysically mediated storage and drainage properties can strongly influence model estimates of watershed scale ET responses to climate variation and climate change. This sensitivity to uncertainty in geophysical properties is particularly true for sites receiving little summer precipitation. A parallel interpretation of this parameter sensitivity is that spatial variation in soil properties are likely to lead to substantial within-watershed plot scale differences in forest water use and drought stress.

scholarly journals Contribution of Cutoff Lows to Precipitation across the United States

2016 ◽  
Vol 55 (4) ◽  
pp. 893-899 ◽  
Author(s):  
John T. Abatzoglou
Keyword(s):  
United States ◽  
Great Plains ◽  
Summer Precipitation ◽  
The United States ◽  
Precipitation Variability ◽  
Western United States ◽  
Spring Precipitation ◽  
Mountain Ranges ◽  
Extreme Precipitation Events ◽  
Slow Moving

AbstractA chronology of cutoff lows (COL) from 1979 to 2014 alongside daily precipitation observations across the conterminous United States was used to examine the contribution of COL to seasonal precipitation, extreme-precipitation events, and interannual precipitation variability. COL accounted for between 2% and 32% of annual precipitation at stations across the United States, with distinct geographic and seasonal variability. The largest fractional contribution of COL to precipitation totals and precipitation extremes was found across the Great Plains and the interior western United States, particularly during the transition seasons of spring and autumn. Widespread significant correlations between seasonal COL precipitation and total precipitation on interannual time scales were found across parts of the United States, most notably to explain spring precipitation variability in the interior western United States and Great Plains and summer precipitation variability in the northwestern United States. In addition to regional differences, a distinct gradient in the contributions of COL to precipitation was found in the lee of large mountain ranges in the western United States. Differences in orographic precipitation enhancement associated with slow-moving COL resulted in relatively more precipitation at lower elevations and, in particular, east of north–south-oriented mountain ranges that experience a strong rain shadow with progressive disturbances.

scholarly journals Patterns and Drivers of Atmospheric River Precipitation and Hydrologic Impacts across the Western United States

2020 ◽  
Vol 21 (1) ◽  
pp. 143-159
Author(s):  
Christine M. Albano ◽  
Michael D. Dettinger ◽  
Adrian A. Harpold
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Water Vapor ◽  
Wind Direction ◽  
Land Surface ◽  
Soil Column ◽  
Western United States ◽  
Antecedent Soil Moisture ◽  
Study Region ◽  
Hydrologic Impacts

AbstractAtmospheric rivers (ARs) significantly influence precipitation and hydrologic variability in many areas of the world, including the western United States. As ARs are increasingly recognized by the research community and the public, there is a need to more precisely quantify and communicate their hydrologic impacts, which can vary from hazardous to beneficial depending on location and on the atmospheric and land surface conditions prior to and during the AR. This study leverages 33 years of atmospheric and hydrologic data for the western United States to 1) identify how water vapor amount, wind direction and speed, temperature, and antecedent soil moisture conditions influence precipitation and hydrologic responses (runoff, recharge, and snowpack) using quantile regression and 2) identify differences in hydrologic response types and magnitudes across the study region. Results indicate that water vapor amount serves as a primary control on precipitation amounts. Holding water vapor constant, precipitation amounts vary with wind direction, depending on location, and are consistently greater at colder temperatures. Runoff efficiencies further covary with temperature and antecedent soil moisture, with precipitation falling as snow and greater available water storage in the soil column mitigating flood impacts of large AR events. This study identifies the coastal and maritime mountain ranges as areas with the greatest potential for hazardous flooding and snowfall impacts. This spatially explicit information can lead to better understanding of the conditions under which ARs of different precipitation amounts are likely to be hazardous at a given location.

scholarly journals Seasonal Precipitation Influences Streamflow Vulnerability to the 2015 Drought in the Western United States

2019 ◽  
Vol 20 (7) ◽  
pp. 1261-1274
Author(s):  
Christopher P. Konrad
Keyword(s):  
United States ◽  
Pacific Northwest ◽  
Summer Precipitation ◽  
Western United States ◽  
Order Model ◽  
First Order ◽  
The Pacific ◽  
Critical Issues ◽  
Desert Southwest ◽  
Normative Models

Abstract Streamflow was exceptionally low in the spring and summer of 2015 across much of the western United States because of a regional drought that exploited the sensitivity of both snow- and rain-dominant rivers. Streamflow during 2015 was examined at 324 gauges in the region to assess its response to the amount, form, and seasonal timing of precipitation and the viability of using spatially aggregated, normative models to assess streamflow vulnerability to drought. Seasonal rain and spring snowmelt had the strongest effects on runoff during the same season, but their effects persisted into subsequent seasons as well. Below-normal runoff in the spring of 2015 was pervasive across the region, while distinct seasonal responses were evident in different hydroclimatic settings: January–March (winter) runoff was above normal in most snow-dominant rivers and runoff in all seasons was above normal for much of the desert Southwest. Summer precipitation contributed to summer runoff in both the Pacific Northwest and desert Southwest. A first-order model that presumes runoff is a constant fraction of precipitation (the precipitation elasticity of runoff, E = 1) could be used for assessing and forecasting runoff responses to precipitation deficits across the region, but runoff generally is more vulnerable to drought (E > 1) than predicted by a first-order model. Uncertainty in spring and summer precipitation forecasts remain critical issues for forecasting and predicting summer streamflow vulnerability to drought across much of the western United States.

Herbicide Control of Locoweeds: A Review

1988 ◽  
Vol 2 (4) ◽  
pp. 460-465 ◽  
Author(s):  
Michael H. Ralphs ◽  
Darrell N. Ueckert
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Plant Growth ◽  
Environmental Conditions ◽  
Plant Density ◽  
Historical Review ◽  
Western United States ◽  
Control Methods ◽  
Poisonous Plant ◽  
Phenoxy Herbicides

Locoweed poisoning of livestock is the most widespread poisonous plant problem in the western United States. This paper presents a historical review of control methods to reduce locoweed plant density. Hand grubbing, the most common method of control before phenoxy herbicides, was practical in small pastures considering the number of livestock saved. Trials in the 1950s indicated that 2,4-D and 2,4,5-T generally controlled locoweeds effectively if applied when plants were actively growing and soil moisture was not limiting plant growth. Picloram, dicamba, clopyralid, and triclopyr provide more consistent control than 2,4-D and 2,4,5-T when applied at less than optimum environmental conditions.

scholarly journals Improving Onion Yield and Market Grade by Mechanical Straw Application to Irrigation Furrows

1999 ◽  
Vol 9 (2) ◽  
pp. 251-253 ◽  
Author(s):  
C.C. Shock ◽  
L.B. Jensen ◽  
J.H. Hobson ◽  
M. Seddigh ◽  
B.M. Shock ◽  
...  
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Wheat Straw ◽  
Allium Cepa ◽  
Water Movement ◽  
Furrow Irrigation ◽  
Western United States ◽  
Water Runoff ◽  
Experiment Station ◽  
Straw Application

Onion (Allium cepa var. cepa L.) is extensively grown under furrow irrigation in the western United States. Wheel compaction of furrows increases water runoff and erosion, and can lead to poor lateral water movement and reduced yields. We studied the effects of 560 to 800 lb/acre (630 to 900 kg·ha-1) wheat straw mechanically applied to the bottom of irrigation furrows on yield and bulb size of sweet Spanish onions in commercial onion fields in 1988, 1990, and 1991, and at an experiment station in 1991 and 1995. Furrows in commercial fields were either compacted with tractor wheels or not. In the commercial fields, straw application increased onion yield in plots with compacted furrows in 1988 and in all plots (with or without compacted furrows) in 1990. At the experiment station, straw mulch increased onion yield 64% in 1991, and 74% in 1995. Straw application primarily increased yields of jumbo (3 to 4 inches; 76 to 102 mm) and colossal (>4 inches; 10 cm) onions, whereas there was no effect on medium (2.25 to 3 inches; 57 to 76 mm) onions. We attributed yield improvements to decreased water runoff and increased lateral water movement and soil moisture.

scholarly journals Holocene Hydroclimate in the Southeastern United States During Abrupt Climate Events: Evidence From New Speleothem Isotopic Records From Alabama

2021 ◽  
Author(s):  
Martin Medina-Elizalde ◽  
Stefan Perritano ◽  
Matthew DeCesare ◽  
Josué Polanco-Martinez ◽  
Gabriela Serrato-Marks ◽  
...  
Keyword(s):  
United States ◽  
Model Simulation ◽  
Southeastern United States ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
Winter Precipitation ◽  
Meridional Overturning Circulation ◽  
Ice Age ◽  
Annual Rainfall ◽  
Spring Precipitation

Abstract We present new high-resolution absolute-dated stalagmite δ18O and δ13C records from the southeastern United States (SE US) spanning the last 12 thousand years (ka). A local relationship between annual rainfall amount and its amount-weighed δ18O composition exists on interannual timescales, driven mostly by an amount effect during summer and spring seasons, and by an isotopically depleted composition of fall and winter precipitation. Based on a novel interpretation of modern rainfall isotopic data, stalagmite δ18O variability is interpreted to reflect the relative contribution of summer and spring precipitation combined relative to combined fall and winter precipitation. Precipitation amount in the SE US increases during the Younger Dryas, the 8.2 ka and Little Ice Age abrupt cooling events. High precipitation during these events reflects enhancement of spring and summer precipitation while the contribution of fall and winter rainfall remained unchanged or decreased slightly. Results from this study support model simulation results that suggest increased precipitation in the SE US during Atlantic Meridional Overturning Circulation (AMOC) slowdown/shutdown (LeGrande et al., 2006; Renssen et al., 2002; Vellinga and Wood, 2002). In association with Northern Hemisphere mid-latitude cooling from the Early to mid-Holocene, annual precipitation in the SE US decreases, a pattern distinctive from that observed during abrupt cooling events related to AMOC shifts. Long-term hydroclimate change in the SE US is likely sensitive to summer insolation reduction as inferred for other tropical and subtropical regions. This study has implications for our understanding of the sensitivity of subtropical hydroclimate to factors both internal and external to the climate system in a warmer climate.

scholarly journals Impact of Sea Surface Temperature and Soil Moisture on Summer Precipitation in the United States Based on Observational Data

2011 ◽  
Vol 12 (5) ◽  
pp. 1086-1099 ◽  
Author(s):  
Rui Mei ◽  
Guiling Wang
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Correlation Analysis ◽  
Surface Temperature ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
The United States ◽  
Sea Surface ◽  
Precipitation Prediction ◽  
The Impact

Abstract This study examines the impact of sea surface temperature (SST) and soil moisture on summer precipitation over two regions of the United States (the upper Mississippi River basin and the Great Plains) based on data from observation and observation-forced model simulations (in the case of soil moisture). Results from SST–precipitation correlation analysis show that spatially averaged SST of identified oceanic areas are better predictors than derived SST patterns from the EOF analysis and that both predictors are strongly associated with the Pacific Ocean. Results from conditioned soil moisture–precipitation correlation analysis show that the impact of soil moisture on precipitation differs between the outer-quartiles years (with summer precipitation amount in the first and fourth quartiles) and inner-quartiles years (with summer precipitation amount in the second and third quartiles), and also between the high- and low-skill SST years (categorized according to the skill of SST-based precipitation prediction). Specifically, the soil moisture–precipitation feedback is more likely to be positive and significant in the outer-quartiles years and in the years when the skill of precipitation prediction based on SST alone is low. This study indicates that soil moisture should be included as a useful predictor in precipitation prediction, and the resulting improvement in prediction skills will be especially substantial during years of large precipitation anomalies. It also demonstrates the complexity of the impact of SST and soil moisture on precipitation, and underlines the important complementary roles both SST and soil moisture play in determining precipitation.

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