Browsing by Subject "precipitation"
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Item Assessing Historical Trends in Snowpack Variability Across the Northern Rocky Mountains Using Remote Sensing and Dendrochronology Approaches(2013-06) Crawford, ChristopherMountain snowpack across the western United States is declining because of warming spring temperatures during the modern period. Earlier snowmelt has been documented for numerous localities throughout the American West using ground-based snow-water-equivalent measurements and gauged streamflow. This research uses historical satellite imagery, tree-ring records, and instrumental climate observations from the northern Rocky Mountain (NRM) region to evaluate the climatic controls on mountain snowpack spatiotemporal variability, assess historical spring snowmelt trends, and contextualize modern climatic change with pre-instrumental climate variability. A suite of methodological approaches is employed to develop and calibrate satellite, tree-ring, and instrumental climate records using time-series analysis techniques. Together, these NRM region climate records suggest that precipitation in the form of mountain snowpack extent varies on interannual to decadal timescales. Of more importance, spring mountain snowpack appears to be decreasing in areal extent during the 20th and early 21st centuries driven largely by modern spring warming.Item Development of a Mathematical Model to Predict the Role of Surface Runoff and Groundwater Flow in Overfertilization of Surface Waters(Water Resources Research Center, University of Minnesota, 1971-06) Johnson, Jack D.; Straub, Conrad P.A nutrient enrichment accounting mathematical model was devised for the New Prague watershed in Minnesota. The New Prague watershed is 23.3 square miles in area and is predominately a rural watershed. Model input data was collected over a 2 1/2 year period from a stream gauging station and two automatic sampling stations. Over 800 water samples were analyzed. Extensive effort was placed on better understanding the nitrogen and phosphorus cycles. It is evident that the spring runoff process and accumulative winter fertilizer applications constitute the major portion of diffuse sources of nutrients in the watershed. Point sources from feedlots and municipal and industrial effluents contribute only 11 percent of the annual EN (total nitrogen, four components) and 7 percent TP (total phosphorus). Disperse sources accounted for 89 percent of EN and 93 percent of TP, with spring runoff in the two months of March and April accounting for 79 percent of the annual EN and 64 percent of the TP. The nutrient output from the watershed could be decreased by increasing penetration of the large amounts of EN and TP in snowpacks into the soil through land terracing to restart rapid spring runoffs and sub-surface drains to allow rapid drainage during the crop season.Item Groundwater Recharge Rates in Minnesota as Related to Precipitation(Water Resources Research Center, University of Minnesota, 1983-03) Kanivetsky, Roman; Palen, BarbaraQuantitative estimates of recharge rates and storage coefficients in sufficient detail are essential to any meaningful state water-resources management, policies, plans and legislation. A methodology was developed to derive quantitative estimates of groundwater recharge rates and storage coefficients for unconfined aquifers in the various hydrologic regions of Minnesota. Recharge estimates are based on information from groundwater hydrographs. Statistical analysis of groundwater level fluctuations and their correlation with precipitation, evaporation, stream discharge were evaluated. Harmonic analysis and autoregression analysis of water levels were done. Storage coefficients were estimated from pumping test data, soil moisture method and empirical equations. Groundwater recharge rates were determined by combining data on groundwater level fluctuations and storage coefficient evaluation for unconfined aquifers in Minnesota. This work is fundamental to the ultimate goal of an interactive water resources model of the state.Item Proceedings of the 1st Agricultural Drainage and Water Quality Field Day(2002-08-14) Strock, Jeffrey S.; Baker, Jim; Busman, Lowell; Gupta, Satish; Moncrief, John; Randall, Gyles; Russelle, Michael; Taylor, ElwynnItem Proceedings of the 4th Drainage Water Management Field Day(2011-08-23) Strock, Jeffrey S.; Gupta, Satish; Sands, Gary; Ranaivoson, Andry; Hay, Chris; Talbot, Mike; Magner, Joe