Between Dec 19, 2024 and Jan 2, 2025, datasets can be submitted to DRUM but will not be processed until after the break. Staff will not be available to answer email during this period, and will not be able to provide DOIs until after Jan 2. If you are in need of a DOI during this period, consider Dryad or OpenICPSR. Submission responses to the UDC may also be delayed during this time.

Browsing by Author "Dadaser-Celik, Filiz"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Lake Evaporation Response to Climate in Minnesota
    (St. Anthony Falls Laboratory, 2008-03) Dadaser-Celik, Filiz; Stefan, Heinz G.
    In this report we analyze the variability of water losses by evaporation from lake surfaces in Minnesota, and trends in lake evaporation for the period 1964 – 2005. Daily evaporation rates were estimated using a mass-transfer equation with recorded daily weather data as input. The weather data came from six Class A weather stations (International Falls, Duluth, Minneaplis/St. Paul, LaCrosse, WI, Sioux Falls, SD, and Fargo, ND). Annual (Jan-Dec) lake evaporation ignoring lake ice-covers and annual evaporation for the actual open-water season were computed from the daily values. Trends in annual evaporation over the periods 1964 – 2005 and 1986 – 2005 were determined using a linear regression method. The trend analysis was repeated for annual water availability (precipitation minus evaporation). Finally correlation coefficients between annual average water levels of 25 Minnesota lakes, and annual evaporation or annual water availability were calculated. In the last 40 years (1964 – 2005), annual average open-water season evaporation ranged from 580 to 747 mm/yr (22.8 to 29.4 in/yr) at the six locations. The trend over the 1964 – 2005 period was upward (rising) at three stations (International Falls, Duluth, and Sioux Falls), and downward (falling) at three stations (Fargo, Minneapolis, and La Crosse). The strongest upward trend in evaporation (0.64 mm/yr) was for Duluth and the strongest downward trend (-1.65 mm/yr) for La Crosse. Annual evaporation for the 12-month (Jan-Dec) period, i.e., disregarding ice covers, was from 79 mm/yr (3.1 in/yr) to 140 mm/yr (5.5 in/yr) higher than annual evaporation computed for the open-water season at the six locations. In the last 20-years (1986–2005) annual open-water season evaporation had a decreasing trend at five of the six locations. The decreasing trends were stronger than for the 1964 – 2005 period and ranged from -0.69 for International Falls and Minneapolis to -1.57 mm/yr for La Crosse. The only positive trend was 1.09 mm/yr for Sioux Falls. Annual average measured precipitation for the 1964 – 2005 period at the six locations ranged from 536 mm/yr to 812 mm/yr (21.1 in/yr to 32.0 in/yr) and showed a rising trend at four 6 of the six stations (International Falls and Duluth were the exceptions). For the 1986 – 2005 period precipitation showed an increasing trend at all stations except Duluth and La Crosse. Water availability, calculated as the difference between annual open-water season precipitation and annual open-water evaporation, showed upward trends at all stations from 1964 to 2005. The trends ranged from 0.05 mm/yr for Duluth to 4.27 mm/yr for Fargo. From 1986 to 2005 five locations showed an upward trend and one a downward trend. The five upward trends were much stronger than for the 1964 – 2005 period, ranging from 0.58mm/yr for La Crosse to 15.06 mm/yr for Fargo. The only downward trend was -2.67 mm/yr for Duluth. Overall, the analysis showed that positive and negative trends in lake evaporation have occurred in Minnesota in the last 40 years. Trends in measured precipitation during the same time period were stronger and upwards. As a result, water availability in Minnesota also has an upward trend. No strong correlation between lake levels, annual evaporation rates or annual water availability was found, but the increase in water availability can explain the observed water level increases in 25 Minnesota lakes.
  • Thumbnail Image
    Item
    Lake Level Response to Climate in Minnesota
    (St. Anthony Falls Laboratory, 2007-12) Dadaser-Celik, Filiz; Stefan, Heinz G.
    We are interested in the variability of lake levels in Minnesota, and the relationship between lake levels and climate. We analyzed historical water levels in 25 Minnesota lakes. Eight were landlocked lakes and seventeen were flow-through lakes. The data were daily values, but substantial gaps existed. The longest record reached back to 1906 (Lake Minnetonka and Upper Prior Lake in Scott County). We determined statistical parameters such as mean annual lake levels and seasonal variations of the historical lake water levels. Linear regression and Mann-Kendall test were used to evaluate the presence of trends in daily, mean annual, spring (May) and fall (October) water levels. The majority of the 25 lakes showed rising water levels in the last century (1906 to 2007). The strongest upward trend was observed in a landlocked lake (Lake Belle Taine in Hubbard County) where the rate was 0.030 m/yr. The second largest increase was observed in a flow-through lake (Marion Lake in Dakota County) with a rate of 0.024 m/yr. Swan Lake (in Nicollet County) and Swan Lake (in Itasca County) were the only lakes that showed a falling trend with a rate of -0.011 and -0.002 m/yr, respectively. The analysis also showed that lake levels have been increasing in most of the 25 lakes in the last 20-years (1987-2006). One landlocked lake and eight flow-through lakes showed their strongest upward trends in the last 20 years. Five of the eight landlocked lakes and eleven of the seventeen flow-through lakes reached their highest recorded levels after 1990. Upward trends in recorded lake water levels were found in both spring and fall in the majority of the 25 lakes analyzed. We also attempted to understand how Minnesota lake levels have responded to climate changes in the past. Correlation coefficients were calculated between annual lake water levels and mean annual climate variables. The correlation of water levels with precipitation was moderate, and the correlation with dew point and air temperatures was very weak. 48- and 36-month antecedent precipitation was the strongest indicator of average water levels. Multivariate regression analysis of lake levels did not improve the lake level predictions. Numerical indicators for ground water and surface water inand out-flows appear necessary for further improvement. The correlation between mean annual water levels was strongest among lakes in the same climate regions and weakest among lakes in distant climate regions. Lake levels in the same Minnesota climate region (with identical precipitation and temperatures) had correlation coefficients as high as 0.78, while those in distant regions were not correlated. The average correlation coefficients among annual water levels in all lakes were 0.43 for the eight landlocked lakes and 0.41 for the seventeen flowthrough lakes. Overall, the analyses showed that changes have occurred in lake levels in Minnesota in the last century and in the last 20 years. The majority of the lakes have rising lake levels. The correlation between climate parameters and lake levels was weak. The consistency of water level variations in lakes of the same region is perhaps the strongest indicator of a climate effect. If the trends continue, lakes included in this study may experience significant water level increase by 2050.
  • Thumbnail Image
    Item
    Stream Flow Response to Climate in Minnesota
    (St. Anthony Falls Laboratory, 2009-04) Dadaser-Celik, Filiz; Stefan, Heinz G.
    The variability of stream flows in Minnesota, and the relationship between stream flows and climate are the focus of this report. We analyze historical flow records of Minnesota streams to determine how much frequency and magnitude of flows have been affected by climate and land use changes. Flow duration analysis, high and low flow ranking, and flood frequency analysis were applied to recorded mean daily stream flows, 7-day average low flows, and annual peak flows. Data from 36 gauging stations located in five river basins of Minnesota (Minnesota River, Rainy River, Red River of the North, Lake Superior, and Upper Mississippi River Basins) covering the 1946-2005 period were used. To detect any changes that have occurred over time, data from the 1986-2005 and the 1946-1965 periods of record were analyzed separately. Flow duration curves were prepared for all gauging stations, and low flows (Q90, Q95), medium flows (Q50), and high flows (Q5, Q10) in the two time periods were examined. Multiple stream gauging stations in the same river basin generally showed consistent changes in stream flows, although deviations from a typical river basin pattern were noted at a few gauging stations. The Minnesota River Basin has experienced the largest stream flow changes compared to the other four basins. High, medium, and low flows have increased significantly from the 1946-1965 to the 1986-2005 period in the Minnesota River basin. The increases in medium to low flows were larger than the increases in high flows. Considerable changes in flows were also observed in the Upper Mississippi River Basin and the Red River of the North Basin. Streams in the Rainy River Basin and tributaries to Lake Superior showed little or no change in stream flow between the 1946-1965 and 1986-2005 periods. The changes observed in these river basins were also variable. In two tributaries to Lake Superior, average flows seem to have increased on the order of 10%, 7-day low flows seem to have decreased, and annual peak flows seem to be unchanged.